Title of Invention	METHOD AND APPARATUS FOR TRANSMISSION BETWEEN STATIONS OF A COMMUNICATION SYSTEM
Abstract	The present invention relates to a method comprising receiving at a device in communication with at least a first station via a wireless interface power control commands from said first station and each of any other stations with which the device is also in simultaneous communication; receiving from a control means further control information associated with a transmission parameter for use by said device for one or more transmissions to said first station; and controlling one or more transmissions from said device to said first station on the basis of a power control command from the station ,that receives transmissions from said device with the best quality parameter, and on the basis of said further control information received from the control means, wherein the further control information comprises a control command selected from a plurality of control commands by the control means.

Title of Invention

METHOD AND APPARATUS FOR TRANSMISSION BETWEEN STATIONS OF A COMMUNICATION SYSTEM

Abstract

The present invention relates to a method comprising receiving at a device in communication with at least a first station via a wireless interface power control commands from said first station and each of any other stations with which the device is also in simultaneous communication; receiving from a control means further control information associated with a transmission parameter for use by said device for one or more transmissions to said first station; and controlling one or more transmissions from said device to said first station on the basis of a power control command from the station ,that receives transmissions from said device with the best quality parameter, and on the basis of said further control information received from the control means, wherein the further control information comprises a control command selected from a plurality of control commands by the control means.

Full Text	Transmissions in a communication system yield of the Invention The present invention relates to a communication system, and in particular, but not exclusively, to transmissions between atations of a communication system. background of the Invention Various different communication systems adapted to px"ovide v/ireless communication between two or more stations are known. wireless communication media may be provided between a station of a communication network and c user equipment. Wireless communication media may also be provided between two user equipment or between two stations of a communication network. A wireless communication systems may be used for various types of communication, such as for voice communication or data communication, A wireless system may provide circuit switched or packet switched services or both. In packet switched services data (e.g. speech data, user data, video data or ether data) is communicated in data packets. The development in the wireless communication has lead to systems that are capable of transporting data in subszantially high data rates i.e. the so called high speed data (HSi:) . An example of wireless communication systems is a cellular communication system. In a cellular system the user equipment may access the communication network via access entities referred to as cells, hence the name cellular system. The skilled person knca's the basic operational principles and elements of a cellular netv/ork and these are therefore not explained herein in any greater detail. It is sufficient to note that a cell can he defined as ar ra.iio access entity that is served by one or several base stallions {BS] serving user equipment (UE) via a wireless interface therebetween. Examples of the crrllular necv/crks include networks that are based on access systems such as the CDMA. (Code Division Multiple Access), WCDMA (Wide-band CDMA), TDMA (Tine Division Multiple Access), FDMA (Frequency Division Multiple Access], or SDMA (Space Division Multiple Access) and hybrids thereof. A wireless communication system is typically provided wich a radio resource management function. A featui'e of the radio resource management is that it may continuously adjust the use ct resources such as the pov/er levels between a rase (transceiver] station and user equipment associated wiwh said bas-:= station during communication between zhe base scat ion and the user equipment. Use of radio resources may be controlled for transmissions that occur from the base station towards the user equipment (downlink) and from the user equipment towards the base station (uplink) . The adjustment is done in order to provide a sufficient quality and reliability for the transmission between the base station and the user equipment in varicus conditions and, on che ocher hand, to reduce power consuTtrpcion and interference caused by the communication to other devices. A user equipment may communication simultaneously with a nurrtber of base stations. Figure 1 shows an example where a user equipment MSI is in communication with two base stations BSl; BS2. The simultaneous r.ommunicaL_on vjith a plurality of base station may ocur-, for example, when a user equipmen, is zo be handed over froir a base station zo anozher base station. The handover may be performed by means of the sc called soft handover procedure. For exaT.ple, in zhe CDMA soft handover may bo used to reduce the interference caused by the user equipment. During a soft handover the zransmission pov;er of a user equipment is typically adjusted based on power control ccnmands from a base station thac requesz for the lowest transmission power. Each base station involved in the soft handover measures the quality of the signal from a given user equipment and sends its pov/er control commands to the user equipment asking the power up or down. The user equipment increases its transmission power only if all base stations involved in the soft handover request for more power. The user equipment xay receive data such as control messages, usei ddta d.i:d sc or. frox. a base station. The user equipment may receive data from more ihan one base statioti. some ot these data zranmission3 may need to be responded by the user equipinent. The response may, for example, be an acknowl edgement that the user equipm.en- did receive the message and/or that the user equipment did accomplish a task in response to the message and/or a response to an inquiry and/or any other feedback that may be required by the base station. The following will discuss a more detailed example that relates to acknowledgem.ents in a third generation wideband code division multiple access (3 3 WCDMA) system. In WCDMA. based systems the above referred high speed data maybe enabled e.g. by means of the so called high speed downlink packet access (H3DPA) technology. The high speed downlink packer access (HSDPA) may include functions such as fast hyhrid automatic repeat request (HARQ), adaptive ceding and modulation (AMC) and/or fast cell selection (FCS) . these functions are kncv/n by the skilled person and will thus not be explained in more detail. A rr.ore detailed description of these and other function of the HSFDA can be found e.g. from a third generation parrnsrship project technical report No. 3G TR25.S43 release 2D00 titled Physical Layer Aspects of UTRA High Speed Dovmlini- Packet Access'. It shall be appreciated that although tho HSDPA has been specified for use in the WCDMA, similar basic principles may be applied to other access techniques. At the present it is assumed that in the high speed downlink packet access (KSD?A) each user equipment receiving data on a high speed downlink shared channel (HS-DSCH) a.so has an associated dedicated channel (DCH) allocated. The dedicated channel aay be xapped to a dedirated physical channel (DPCH) in the physical layer. Vhe DPCH is typically divided into dedicated physical data channel {DPuCIi; and dedicated physical control channel (DPCCH] both in the uplink and the downlink. Data such as the power control commands, transport format information, and dedicated piloc symlDols are transmitted en the D?CCH. Information such as diversity feedback infcrmaticn may also be transmitted on DPCCH in the uplink. The HS-DSCH may be mapped to one or several high speed physical downlink shared channels {!IS-PDSCH) in the physical layer. The associated dedicated channel is tyPcally provided bo-h in the downlink and r.he upink. The dedicated channel is typically used to carry H3DPA related information/signalling as well as other dedicated data such as speecn and control data. The user equipment may com'tiunicate with several base stations at the same time. For example, the associated dedicated channel may be in soft handover. In addition to associated dedicated channels, che HS-D3CH may be associated also with a shax'ed control channel (3CCH) . The SCCH can be used to carry HS-DSCH specific information/signalling to those users receiving data on uhe HS-DSCH. A current proposal is to use the dedicated channel to inform the user equipment that it has data to be read on the HS-DSCH and SCCH. That in, only those users receiving data at a given time will receive an indication on the dedicated channel. The dedicated channel may be called as a pointer o^hannel since it points to the shared channels. The dedicated channel may also contain information about modulation and coding schs'iries, power levels and similar parameters used for che shared channels. This information can be sent also on the shared channel. The shared control channel on the other hand is used to carry information that is specific to the data t:ransmi:ted on the shared data channel (HS-DSCH) . This xafortnation can contain for instance packet numbers for the HARQ and so on. The shared control channel can be cent on a separate code channel (code multiplexed; or using the same code channels as llS-PDSCn (time multiplexed) . Unlike the dedicated channel, the HS-DSCH is assumed noc to be in soft handover. That is, each base station is assumed ro have their own shared channel and the user equipment is assumed -c receive data from only one base station at a time. The so called fast cell selection (FCS) technique may be used to swicch the data transmission from one base station co another. However, the shared channels does not use pov/er control. Instead, the shared channels are proposed to be nransmitced with fixed or seri-fixed pov/er. The Lena 'sen-.i-fixed' means in here than the power is not changed often. The power could, for instance, be a cell specific parameter. In the currently proposed arrangements the high speed downlink shared channel iHS-D3CH) is planned to be associated with a dedicated channel which would carry in the downlink at least information regarding the timing when the receiving station is to receive on a shared channel. The associated dedicated channel may possibly carry also other information. In the uplink, the associated dedicated channel may carry, for example, the required acknowledgements (ACK) for a fast HARQ. The inventor has found that chis may be problematic for examaple in the context of the uplink power control of the fasz HAEQ acknowledgements. A problematic situation may cccur especially when the associated dedicated channel is in the soft handorer mode. During the soft handover the uplink power is adjusted in accordance v;ith the best quality uplink among an active set cf base stations. However, signalling on the high speed shared channel may be transmitted from another bass station. The communication link between the user equipment and said other base station may be of poorer quality than said best uplink connection. Nevertheless, said ether rase station extects to receive responses such as an acknowledgement frorr. the user equipment. Since the quality of this uplink connection may be of substantially poorer q^jality than what the best uplink is, there is a risk that "he response is net properly received and decoded or is not received at all. The fast cell selection function may be used to guarantee in some occasions that best possible downlink is utilised for communication towards the user equipment. However, the base station that provides the best uplink may be different than the base station providing the best downlink. This may be so, for example due to fast fading or other changes in the signalling conditions. This may increase the unreliabilizy of the responding functional ir.y. The prior art proposals for solving this problem include so called strong coding, e.g., by using repetition coding. In the repetition coding the acknowledgcmcnt (ACK) bit or bits iS/are repeated several times. This, however, may cause too much additional load on the air interface and/or reserve too much of the radio resources if one wants to guarantee the correct reception of -he acknowledgement message. Anouher prior art proposal is the so called fixed power offset for acknowledgement (ACK) transmissions. This cneans that all acknowledgement messages are transmitued with increased or a certain power in order to ensure that the acknowledgement is received ever, through the poorest quality uplink. However, even a fixed power level for acknov;ledgenent messages may not completely so_ve the prcolem of substantially poor signalling conditions. Thus situations v/here the pov/er is not high enough Tay still occur. On the other hand, it is also possible thaz the fixed power level is unnecessarily high. Thus, in addition to reliability problems this approach may be disadvantageous in that too high power is used by the user equipmsni causing incerference and unnecessarily high pov/er coiisumpLion. Summary of the Invention Embodiments of the present invention aim to address one or several of the above problems. According to one aspect of rho present invention, there is provided a method for communication between a first station and a second station, comprising: ccmmunicatinf from the first station to the second station information associated -A-ith the manner how the second station should transmit towards the first station; and transmitting from the second station based on said information from said first station instead of transmitting in a manner the second station would have transmitted had it not been provided with said information. In a specific embodiment said information is transmitted on a dedicated channel from the first station to the second station. In another specific embodiment said mformation is communicated in a message that is transmitted from the first station to a second station, A response to the message is then transmitted from the second station based on said informatino. The second station may transmit v/ith a transmission power that has been set based on said information after having received the information. The second station may repeat the transmission, ths number of transmissions depending on said information. Said information may define an offset parameter, the power level cf the transmission being shifted an amount as indicated by said offset parameter for the transmission. In an additional step the quality of the interface between nhe firsr and second stations is determined. The information to be transmitted to the second station is then defined by the first station based on said determination. The second station may be in communication with at least one further station, said further station providing control instructions to the second station. The second station may be involved in a handover between said at least two stations. The second station may bo in a soft handover mode. According to another aspect of the present invention there is provided a communication system comprising: a station; a user equipment for communication with the station via a wireless interface, said user equipment being adapted to control at least one transmission parameter; and control means adapted for provis-cn said user equipment with information associated with a transmission parameter for use by the user equipment when transmitting to the station, the user equipment being enabled to transmit with a different trarnsmission parmeter based on said information than what the transmission parameter would be if the user equipment had not been provided with said information. At least one further station may be provided, said furzher station being adapted for communication with the user equipment, the arrangement preferably being such that the U3cr equipment is adapted to follow control instructions from said further station unless said information is crcvided thereto. According to another aspect of the present invention there is provided a station for a communication system ccrriprising ccncrol means for generating a message to be comrr.unicated from the station to another stacion, said control means being adapted to provide said other station with information associated with a parameter for use by said other station for use in control cf communication from said other s~ation to the station when responding the message. According to another aspecc of the present invention there is provided a user equipment for communication with a stacion of a communication system via a wireless interface, comprising means for receiving a message from the station and control means for transmitting a response to the message, v;herein the user equipment is adapted to transmit the response in accordance with control information received with the message. Brief Description of Drawings For better understanding of the present invention, reference will now be made by way of example to the accompanying drawings in which: Figure 1 shows an access system wherein the present invention may be embodied; Figure 2 is a flowchart illustrating the operation of an embodiment of the present invention; and Figure 3 shows a specific embodiment. description of Preferred embodirrents of the Invention An embodiment will now be described with reference to a mobile telecommunication system. The exemplifying communication system comprises a radio access part adapted Lo operate based on the WCDI (Wideband Code Division Multiple Access) technique. A fearture of the WCDMA based systems is that a plurality of user equipment is allowed to communicate with a base transceiver station in a cell ever a radio interface (only one user equipment, however, is shown in Figure 1 for clarity) . As shown by Figure 3 , a user equipment is also allowed to be in radio communication with more than one base station at the same time. Figure 1 shows only two base stations BSl, BS2 for clarity. The user equipment comprises a mobile station MSI. The term mobile station refers to a mobile user equipment that is enabled to move from a location to another. A mobile station may also roam from one network Lo another network, if the other network is compatible with the standard the given mobile station is adapted to and there is a roaming agreement between the operators of the two networks. Each of the base stations BSl, 1232 may be provided v;ith a controller entity BCE. The controller entity may be adapted to perform various task, such as to measure and control power levels that are used for communication between the base station ard thr mobile station .YSl. In addition to the controller entity of the base staticn, the operation of the base station may also be controlled by at least one furthe-controller entity, such as a radio network controller NC. The arrangement is typically such the various control functions associated wich a base station are divided between the controller enzity of the base station and a network controller entity. A network controller entity nay be adapted to control one or several base stanicns. The various network controller entities may be connected to each other for communication therebetween. Communication between the mobile station and the base stations may comprise any kind of data such as speech data, video data or other data. The base stations and mobile station communicate also control data. The control data may associate with management operations. The control data may comprise messages such as various request and acknowledgements. Data may be transmitted between the stations as a plurality of data symbols in subsequent data or radio frames. The signals carrying the data may be transmitted with variable data symbol transmission rates (data speeds) , wherein the transmissioa rate may be different in subsequent frames of the transmission. The data symbols may be transmitted based on different access techniques. For example, in the -ZDMA (Code Division Multiple Access) system data is encoded for transmission by processing data symbols to be transmitted by a spreading code for each transmission channel. In the TDMA. (Time Division Multiple Access) system data is transmitted in different time slots allocated fcr different channels. The communication between che mobile station MSI and the base stations BSl and 3S2 may occur via different communication channels, such as via a dedicated channel, shared channel and 30 on. In some systens such as the CDXA the channels may be distinguished from cne another by the use of scrambling codes in a manner which is known by the skilled person. In Figure 1 the different signalling conditions betv;een the mobile station and the base stations are illustrated by different widths of the arrows betv;een the stations. As shown. base Ecaticn BSl has a weaker uplink with the mobile station MS1 than the other base station ES2. This implies that the power control of the uplink following the base station BS2. Hovjever, as shown in Figure 1, the downlink from base station BSl may be strcnger than what the downlink from the base station 3S2 is. Each of the base stations of Figure 1 may be enabled to measure one or more paraneter that associate with the connection. The parameter may be a quality parameter such as the power levels or signal to interference (SIR) level in the uplink. That is, the power level or SIR level az which each base station BSl, BS2 receives from the mobile station MSI may be known by the respective base station. The power control mechanism in the access network is typically such that the mobile station MSI follows the power commands received from the "strcngest" base station, e.g. the base station BS2 that receives the signal transmitted by MSI with the best quality parameter. The transmission power of the mobile station MSI is then adjusted accordingly even if the other base station BSl keeps on asking for more transmission power. This is so since the mobile station MSI only increases transmission power if all "hose base stations that are in soft handover with the mobile station MSI ask for more power. In the following example it is assumed that in normal operation the mobile station MSI adjusts it transmission power based on the power commands received from the base station BS2. The power adjustment mechanism may be based on use of the so called quality target or power threshold values. If the quality of the connection is below the target value, the mobile station XSl is asked to increase the transmission power and if the quality is above the target, the power is asked tc be decreased. The connecuion quality target can be announced e.g. by means of so called Eb/No (Signal Energy/Noise) or SIR (Signal to Interference Ratio) or desired signal level carget or a similar param.eter indicating a quality measure v/hich can be estimated for the connection between two stations. The quality of the connection is controlled based on the target value. Any of the connection parameters that have influence to the quality of the connection should follov; any changes in the target. In most cases it is sufficient if the transmission power is increased/decreased in order to meet the quality target value. A more detailed description of a possible closed loop power control mechanium can be found, for example, from 5GPP (third generation partnership project) technical specification No. TS25.214 "Fhysical layer procedures (FDD)". In addition to the cloased loop power control mechanism the CDMA systems may includs also an outer loop power ccntrol mechanism. This nay adjust the power or SIR target based on other quality target parameters such as the bit error rate (BER) or frame error rate (FER) or any other similar quality target the connection should meet. In che embodiments a first station may transmit data or a request or an enquiry tc a second statinn. After x-eception of said transmission the second station then transmits a response back to the first scacion. To improve the reliability and/or optimise -he use of resources, information associated with at least one parameter for the response is signalled from -he first station to the second station, This parameter may, for example, associate with the required power levels of the response and/or the nunber of times the response shall be transmitted and so on. The response signalling is then performed based on the received information. In the Figure 1 example the first station is the base station BSl and the second station is the mobile station MSI. For example, when the base station BSl allocates a channel to the mobile station MSI and sends data thereto on the high speed daua shared channel (KS-DSCH) , the base station BSl expects the mobile Gtation to return an acknowledgement (ACK), The base station BSl may provide the mobile station with information on an associated control channel (either dedicated or shared) regarding the power levels required for the response. In = preferred embodiment the information provides the mobile station MSI with an offset value. The offset value indicates the difference in power relative to power level used for transmission in the best uplink with the base staticn 3S2 . The base station 3S1 determines the offset that is needed for the reliable acknowledgement transmission from the mobile station MSI based on one or more measurements associated with transmissions from -he mobile staticn. The power is determined such that a predefined level of reliabality is obtained for the decoding of the acknowledgement at the base staticn 3Si. The mobile station r that the response transmission needs to be accomplished m a different power level than what is used for communication with the best base station 3S2 and control the transmission accordingly. The acknowledgement message (ACK) may be transmitted back to the base stativon BSl on a dedicated channel. The dedicated channel may be 'on' all the time even if there is no acknowledgements to be cent. This is so in order to keep the closed loop power control running. The active base station BSl may measure a quality parameter such as the signal to interference ratio (SIR) of this dedicated channel for overall power control purposes. This may be done e.g. based on so called pilot bits that are transmitted by the mobile station. Thus the case station BSl can calculate a required power offset. The power offset requirement is signalled from the base station BSl to the mobile station MSI with the downlink data packet to tell the mobile MSI how much more power is required for the acknowledgement transmission. New signalling bits may be added in rhe downlink transmission from the base station BSl to tell the required power offset for the user equipment MSI. These bits may be sent, e.g., or. the shared contrcl channel since only the user equipment or those user equipment receiving on the downlink shared data channel need to send the acknowledgement ACK. That is, this information is not needed all the tine, but only when there is data packets to acknowledge. Alternatively, the base £tat.ion may sent these bits to the user equipment via a dedicated control channel or dedicated data channel. The power control may be accomplished in a slot by slot basis in access techniques vherain the transnissions occur in slots. A transmission can be dividea into the slots e.g. based on time or by means of a spreading code. The mobile station MSI may be adapted to assign power for the slots in accordance with a "normal" power control mechanism unless the mobile station has been provided with informiation which requires use of a different power Isvel for a slot (or several slots) that are allocated for the response. Tn a simple naae one bit may be enough for the provision of the above referenced information. For example, ' C' could indicate that an offset of 5dB is required and '1' cculd indicate an offset of lOdB. According to another possibility '0' could indicate that no offset is required and '1' could indicate that a predefined additional power is required. 2 to 4 bizs may be used in a typical application for defining 4 to 16 different power offset levels. A step between the different power levels may be, for example, 2, 5 or 10 d3. Alternatively the step size between the power levels may be adapted to change nonlinearly. A more specific embodiment vjill now be described with reference to Figure 3 shov;ing transmission of data packers between a base station (node B) and tv;o user equipment UEl and UE2. It shall be appreciated that although Figure 3 3hov;s channels in association with only one base station, a plurality of base stations may have communication channels with the user equipment UEl and/or UE2 at the same time. Otb«r channels are, however, not shown for reasons of clarity. A number of packets is shov/n to be transmitted -ic a first user equipment UEl and to a second user equipment UE2 on the data channel HSPDSCH. The vertical lines of Figure 3 dividing the transmission into secticns indicate a high speed dovmlir.k packet access trans-ission time intervals 'HSDPA TTI). The HSDPA TTI is a collection of a defined number of slots. That is, the high speed dovmlink packet access transmission time interval (TTI) defines a period for data transportation between user equinmFint and a base station via the high speed downlink shared channel (HSDSCE) . Logically the TTI can thus be seen to correspond the concept of data frames. In the Figure 3 example eight TTIs arc shown, each '-TI being three slors in length. In the following it is assumed that the acknowledgements are provided in accordance with the fast hybrid automatic repeat request (HARQ) scheme. A so called K-channel HARQ is also assumed tc be used for the tast HARQ together with a so called stop-and-wait protocol. The stop-and-wait protocol may be used in order to reduce buffering requirements of the receiving staticn. The N-channel HA?.Q supports asynchronDus transmission. Thus different users can be scheduled freely without need to waiu for completion of a given transmission. The receiving station may need, however, to know to which KARQ process the packer belongs to. This information can be explicitly signalled on a high speed do^vnlink packet access (HSDPA) control channel iCH) , e.g. che SCCH. For example, after three packets have been cransporzed to the first user equipment USl, two packets may be transmitted to the second user equipment: UE2. The transmission co the first user equipnenc L'El may in such case be delayed by two TTIs. The processing nimes of data packet to different user equipment should be defined such that continuous transmission co a user equipment is possible. Each packet is preferably acknowledged during the transmission of ether packets so that the downlink (DL) channel can be kept occupied all the time when there are packets no be transmitted. In Figure 3 the uplink acknowledgements are shown to be transmitted on the dedicated physical control channel (DPCCH). Arrov/D Rl to R9 indicate various relations between different operations. That is, relations between pointer bits on the DL npCF, shared data and control channel (HS-PDSCH and SCCK] cransmission and the acknowledgement transmissions. More particularly, each of the double lined arrows R2, R5 and R9 indicates a quality mcasurement performed for the uplink of a given user equipment en the respective dedicated control charjiel. The single lined arrows Rl, R4 and R6 indicate the relationships between the pointer bits and shared control channel SCCH in the downlink. The single lined arrows R3 and R6 indicate the relationships between the dcwnlink data channel HSPDSCH and acknowledgements in the uplink. The acknowledgements are transmitted with a power that has been adjusted based on information received on the SCCK, that is based on the results of the measurements. During the first interval TTIl the base station transmits a pointer bit to the user equipment UEl. The pointer hit indicates that the user equipment UEl shall receive data and control information during the next TTI (TTI2) on the HS-PDSCH and on the SCCH. Also during TTIl, the base station measures the quality of the uplink of the user equipment UEl. These relations are shown by the relation arrows Rl and R2, respectively'-. For example, the GIR of the uplink can be measured from the dedicated pilot symbols -ransmit-ed on the DPCCH in every slot. Based on chis cjuality measurement, the base station provides the user equipment UEl in the TTI2 with information regardip.g the power level that should be used whan transmitting the acknowledgement during TTI4. This relation is indicated by arrow R3. The power level information can be provided as a power offset, as explained above. Ibis power offset information may be, for example, provided as a field of a fev/ bits in the shared control channel (SCCH) . It should be noted that the ncasuremencs may be averaged over a longer period of time or othcrwioe processed. the arrow R2 simply shews chat the power offset used for the transmission is based on the measurement (s) done before the transmission of the power offset. After having received the power level information the user equipment USl sends the acknowledqement using a power level chat is based on informationi from the base station. The acknowledgement may be a positive acrznowledgement (A in Figure 5} or a negative ackncv/ledgemenc (N ir. Figure 3) . In Figure 2, some of the acknowledgement slots are shewn to be higher in order to illustrate that increased transmit power is used for" these acknowledgements. The increased power may be applied for the whole slot or only on the acknowledgement bits within the slot. The same incr-eased power may also be used in other clots it they contain other information such as measurement or quality report which is senc only to the same base station as rhe acknowledgeTrp.nr.. The increased power may also be applied to the entire TTI or even a number of TTIs . In addition to relations Rl to R3, Figure 3 illustrates also a second set of relazions R4 to R9 that associate with the user equipment UE2. In this case the acknowledgement was negative (N) and thei-efore a new pointer bit was given on the DTi CFCK channel of the second user equipment UE2 for retransmission of the message. In order to ensure that the power level for the response can be determined appropriately by the base station the uplink quality measurement is preferably accomplished as late as possible. As shown, information asscciated e.g. with the neasurement as indicated by the arrcw R2 is transmitted in the next transmission time incerval (TTI2) on the control channel (DLSCCII) . The embodiments are especially suitable for acknowledgements because the acknowledgements need to be cent in response to a downlink transmission and also because the reliability of the acknowledgement transmission should be high. The message specific control information may be signalled only when the f'.rst station determines that a different parameter is needed in order to ensure a reliable response by the user equipment. Figure 4 shows a further embodiment m which thr user equipment first follows power commands from the strongest base station, that is from a base station 3S2. Another basa station B51 sends a power offsetl' message to the user equipment. After having received the 'power offsetl' message the power control function of the user equipment s::arts to follow said other base station. The user equipment power control nay set ics transmission power based on the message from the base station BSl for a predetermined time. The user equipment may alternatively follow the commands from the base station BSl as long as it has some information, such as acknowledgements or measurement reports or so on to be sent to this base station. The user equipment may also wait for new power offset information from any of the base stations it is in connection v/ith. That is, a new offset such as the shown *0ffset2' will replace the previous offset parameter. ' When the user equipment power ccntrcl returns to the "normal" soft handover mode the user equipment may change (typically decrease) its power back to the level it used before receiving the offset command Of.setl ' . That is, the user equipment may start to follov; the power control commands from the strongest base station 3S2 having the bcst uplink with the user equipment:. This may be accomplished by using offset parameter that equal with the first offset (i.e. offset2=offsetl in Figure 4) informed by the base station BSl or a predetermined second offset (offset2). The second offset may be a function of the said first offset. The second offset may also be informed by the base station BS2 having the best upl.nk. In a further embodiment each base station in connection (for instance, in a soft handover) with the user equipment may continuously measure the quality of the uplink. Ir. addition to or instead of the normal power control commands each of the base stations may send power offset information to the user equipment telling how much the power should be changed (increased or decreased) in order to meet the quality target. This information is preferably sent on the dedicated control channel. In a normal soft handover case zhe user equipment may then use the offset that results in the lowest transmission power or alternatively tollow the normal pov/er control commands. However, when the user equipment has something to send to one base station only, the user equipment may then use the power offset sent by that base station. The offset may be sent periodically, e.g., in each clot as the power control commands, or once per every n slots and so on. The offset information may also be sent when needed, e.g., when the value of the offset exceeds some threshold values. In an embodiment the user equipment may also be forced to use stranger coding for the transm.ission of the acknowledgement message. For example, the user equipment may be instructed tc transmit the acknowledgement repeatedly. For example, instead of sending the acknowledgement once the user equipment may be instructed to transmit the acknowledgement three, five, or ten times and so on. According to an embodimenc the user equipment is instructed to transmit che acknowledgement e.g. in three slots instead of one slot so chat the acknowledgement can be decoded reliably. The above discussed transmission parameter information provision mechanism may also be used in connection with ether signalling functions than acknowledgemencs. The response messages could be, for example, measurement reports or other reports. The herein proposed signalling mechanism may be especially advantageous if a report is requested by a base station of a plurality of base stations in communnication with a user equipment. The base station may inform the user equipment of the power offset and/or any other parameter that is to be used for the response towards the specific base station. The above discussed adjustment of at least one feature of the response signalling based on information from power level measurements. The adjustment may also be based on other information that associates v;ith the interface between the two stations. For example, the base station BSl may request for a certain power offset based on analysis of the previous responses from the mobile station MSI. If the analysis indicates that a certain number of responses has net been correct, the offset may be increased in order to improve the reliability. The responses may be earlier ACKs or other data-transmitted from the user equipment, e.g., speech packets. It is noted that the above disclosed solution is applicable also in instances where the first message is sent from the user equipment to a base station. In such a case the user equipment may inform the base station of any requirements chat it may have for the response from the base station. It shall be appreciated that whilst embodiments of the present invention have been described in relation to mobile stations, embodiments of the present invention are applicable to any other suitable type of user equipment. It shall be appreciated that whilst embodirents of the present invention have been described in relation to a mobile station that is in communication with more than one base station, the present invention is applicable also to instances where only two station are in communication with each ether. For example, a first scation transmitting a message that is to be respcnded by a sftnond station may insert in the message information regarding e.g. coding and/or power that is to be used for responding to the particular packet. It shall be appreciated that while this specification mentions some system specific examples of the communicacior. channels the embodiments of the invention are noz restrictsd by tnese examples. The rcsponse may also be sent, for example, on a shared control channel or a data channel in systems where such a channel is defined. P. specific acknowledgement channel may also be defined. The data is described as being in packet form. In alternative embodiments of the invention the data may be sent in any suitable forma-:. In addition, it is net always necessary to measure the quality of the connection for each data packet and/or to provide the user equipment with the offset information each time a response is required. Instead, the measurement may be accomplished and/or information transnitted e.g. in predefined intervals or in response to a predefined event (e.g. the quality of the connection has changed cr tne user equipment has been relocated from a network controller to another network controller and sc on) , It may thus be enough if the offset information is provided once for the user equipment during a connection between the user equipment and a base station. The en±:cdiment of the present invention has been described in the context of a CDMA system. This invention is also applicable to any other access techniques including time divisicn multiple access, frequency division multiple access or space division mulultiple access as well as any hybrids thereof. It shall be appreciated that the base station may in some communication standards, such as those associated with the 3^^ generation (3G) universal mobile telecommunications system (UMTS) , be referred to as node 3. Hov/ever, this specif icacion has used the term base station for clarity. According to an alternative solution for the above discussed problem a dedicated physical channel (DPCK) is used only in association with a high speed downlink shared channel (HS-DSCH} . That is, no ocher data is transmitted on the DPDCH. The pcwsr control of the DPCH may then follow base sea-ion that transmits on the active IIS-DSCH (both in the uplink and che downlink) instead of the best base station. If no other daza is transported on the uplink DFDCH, then the uplink power control function of the m.obile station could follow Lhe active high speed da-a base station. In such a situation informaLion regarding the power ortset may not be needed for the uplink, since the pov;er control function may adjust the power. It is also noted herein that while the above describes exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution withcut departing from the scope of the present invention as defined in the appended claims. Claims 1. A nsthod for communication between a first, station and a second station, comprising ccmrr.unicating from the first station to the second station information associated with the manner how the second station should transmit towards the first station; and transniting from the second station based on said information from said first station instead of transmitting in a manner the second station would have cransmitted had it not been provided with said information. 2. A method as claimed in claim 1; wherein said information is transmitted on a dedicated channel from the first station to the second station. 3. A method as claimed in claim 2. wherein the transmission of said intormation is periodic. 4. A method as claimed in claim 1, wherein said information is communicated in a message transmitted from the first station to a second station, and wherein a response to the message is transmitted from the second station based on said information. 5. A method as claimed in any preceding claim, wherein the second station cransmits with a transntissica power chat has been set based on said information. 6. A method as claimed in any preceding claim, wherein the second station repeats the transmission cf the response, the numoer of the transmission depending on said information. 7. A method as claimed in any preceding claim, wherein said information defines an offset to a power level paramezer, and wherein the power level cf the transmission is based on said offsat. 8. A method as claimed Ln claim 7, wherein the predefined power level is defined by a connection quality threshold paraT.eter. 9. A method as claimed in any preceding claim, wherein said information is transmitted from the first station to the second station on a control channel, 10. A method as claimed in claim 9 when dependent on claim 1 or any of claims 4 to 3, wherein said control channel is a shared channel. 11. A method as claimed in claim 9, wherein said control channel is a dedicated control channel. 12. A method as claimed in claim 4 nr any claim dependent on claim 4, wherein the response is transmitted on a dedicated data channel. 13. A method as claimed in claim 4 or any of claims 5 to 11 when dependent on claim 4, wherein the response is transmitted on a dedicated control channel. 14. A method as claimed in claim 4 or any of claims 5 to 11 when dependent on claim 4, wnerein tne response is transmitted on a shared control channel. 15. A method as claimed in claim 4 or any of claims 5 to 11 when dependent on claim 4, wherein the response is transmitted on a shared data channel. 15. A method as claimed in. claim 4 or any claim dependent on claira 4, wherein the response comprises an acknowledgement. 17. A method as claimed in any preceding claim, wherein the transmission from r.he Bficond station comprises a report requested by the first station. 18. A method as claimed in claim 17, v/herein the report comprises a measurement report or quality report. 19. A method as claimed in any preceding claim, comprising determining the quali-y of the interface between the first and second stations, and defining the infcrmaticn to be transmitted to the Decord staticn based on said determination. 20. A trerhod as claimed in claim 19, v/herein step of determining comprises measuring signal to interference ratio cr a power level of the interface from the second station to the first station. 21. A method as claimed in claim 19, wherein step of determining comprises deterrr.ining the rate of successful and/or unsuccessful responses or transmissions from the second station at the first station. 22. A method as claimed in claim 4 or any claim dependent on claim 4, wherein the message comprises at least one data packet. 23. A method as claimed in claim 4 or any claim dependent on claim 4, wherein the message and response procedure is based on a hybrid automatic repeat request scheme. 24. A method as claimed in any of claims 1 to 2; comprising returning the second station into a mode where it transmits in accordance with usual transmission procedures of the communication system the stations belong to. 25. A method as claimed in any preceding claim, wherein the first station comprises a base station cf a cellular communication system. 26. A meuhod as claimed in any preceding claim, wherein the snccnd station coaiprises a mobile user equipment. 27. A method as claimed in claim 25 cr 26, wherein the station communicates based on the code division multiple access mode. 28. A method as claimed in any preceding claim, wherein the second station is in communication with at least one further station, said further station also providing control instructions to the second station. 29. A method as claimed in claim 28, wherein the second station is involved in a handover between said at least two stations. 30. A method as claimed in claim 29, wherein the second station is in a soft handover mode. 31. A ccmmunication sysiem comprising: a station; 5 user equipment for communication with the station via a wireless interface, said user epuipmcnt being adapted to contrcl at least one transmission parameter; and control means adapted for provision said user equipment with information associated with a transmission parameter for use by the user equipment when transmitting to the station, the user equipr.ent being enabled to transmit with a different transmission carameter based en said information than what the transmission parameter would be if the user equipment had not been provided with said information. 32. A communication system as claimed in claim 31, comprising at least one further station adapted for communication with the user equipment and v/herein the user equipm.ent is adapted to follow control instructions from said other station unless provided wi-h said information. 23. A communication system as claimed in claim 31 or 32. comprising means for generating a message to be transmitted from the station to the user equipment, and wherein the user equipment is adapted to transmit a response to the message based on said information. 34. A station for a communication system comprising control means for generating a message to be communicated from the station to another station, said control means being adapted to provide said other station wich information associated with a parameter for use by said other station for use in control of cornmunication from said other station to the station -when responding the message. 35. A user equipment for communication with a station of a communication system via a wireless interface, comprising: means for receiving a message from the station; control means for transmitting a response to the message, wherein the user equipment is adapted to transmit the response in accordance with control information received with the message. 36. A method for communication, substantially as hereinabove described and illustrated with reference to the accompanying drawing.

Full Text

Transmissions in a communication system
yield of the Invention
The present invention relates to a communication system, and in particular, but not exclusively, to transmissions between atations of a communication system.
background of the Invention
Various different communication systems adapted to px"ovide v/ireless communication between two or more stations are known. wireless communication media may be provided between a station of a communication network and c user equipment. Wireless communication media may also be provided between two user equipment or between two stations of a communication network.
A wireless communication systems may be used for various types of communication, such as for voice communication or data communication, A wireless system may provide circuit switched or packet switched services or both. In packet switched services data (e.g. speech data, user data, video data or ether data) is communicated in data packets. The development in the wireless communication has lead to systems that are capable of transporting data in subszantially high data rates i.e. the so called high speed data (HSi:) .
An example of wireless communication systems is a cellular communication system. In a cellular system the user equipment may access the communication network via access entities referred to as cells, hence the name cellular system. The

skilled person knca's the basic operational principles and elements of a cellular netv/ork and these are therefore not explained herein in any greater detail. It is sufficient to note that a cell can he defined as ar ra.iio access entity that is served by one or several base stallions {BS] serving user equipment (UE) via a wireless interface therebetween. Examples of the crrllular necv/crks include networks that are based on access systems such as the CDMA. (Code Division Multiple Access), WCDMA (Wide-band CDMA), TDMA (Tine Division Multiple Access), FDMA (Frequency Division Multiple Access], or SDMA (Space Division Multiple Access) and hybrids thereof.
A wireless communication system is typically provided wich a radio resource management function. A featui'e of the radio resource management is that it may continuously adjust the use ct resources such as the pov/er levels between a rase (transceiver] station and user equipment associated wiwh said bas-:= station during communication between zhe base scat ion and the user equipment. Use of radio resources may be controlled for transmissions that occur from the base station towards the user equipment (downlink) and from the user equipment towards the base station (uplink) . The adjustment is done in order to provide a sufficient quality and reliability for the transmission between the base station and the user equipment in varicus conditions and, on che ocher hand, to reduce power consuTtrpcion and interference caused by the communication to other devices.
A user equipment may communication simultaneously with a nurrtber of base stations. Figure 1 shows an example where a user equipment MSI is in communication with two base stations BSl; BS2. The simultaneous r.ommunicaL_on vjith a plurality of

base station may ocur-, for example, when a user equipmen, is zo be handed over froir a base station zo anozher base station.
The handover may be performed by means of the sc called soft handover procedure. For exaT.ple, in zhe CDMA soft handover may bo used to reduce the interference caused by the user equipment. During a soft handover the zransmission pov;er of a user equipment is typically adjusted based on power control ccnmands from a base station thac requesz for the lowest transmission power. Each base station involved in the soft handover measures the quality of the signal from a given user equipment and sends its pov/er control commands to the user equipment asking the power up or down. The user equipment increases its transmission power only if all base stations involved in the soft handover request for more power.
The user equipment xay receive data such as control messages, usei ddta d.i:d sc or. frox. a base station. The user equipment may receive data from more ihan one base statioti. some ot these data zranmission3 may need to be responded by the user equipinent. The response may, for example, be an acknowl edgement that the user equipm.en- did receive the message and/or that the user equipment did accomplish a task in response to the message and/or a response to an inquiry and/or any other feedback that may be required by the base station. The following will discuss a more detailed example that relates to acknowledgem.ents in a third generation wideband code division multiple access (3 3 WCDMA) system.
In WCDMA. based systems the above referred high speed data maybe enabled e.g. by means of the so called high speed downlink packet access (H3DPA) technology. The high speed downlink packer access (HSDPA) may include functions such as fast

hyhrid automatic repeat request (HARQ), adaptive ceding and modulation (AMC) and/or fast cell selection (FCS) . these functions are kncv/n by the skilled person and will thus not be explained in more detail. A rr.ore detailed description of these and other function of the HSFDA can be found e.g. from a third generation parrnsrship project technical report No. 3G TR25.S43 release 2D00 titled Physical Layer Aspects of UTRA High Speed Dovmlini- Packet Access'. It shall be appreciated that although tho HSDPA has been specified for use in the WCDMA, similar basic principles may be applied to other access techniques.
At the present it is assumed that in the high speed downlink packet access (KSD?A) each user equipment receiving data on a high speed downlink shared channel (HS-DSCH) a.so has an associated dedicated channel (DCH) allocated. The dedicated channel aay be xapped to a dedirated physical channel (DPCH) in the physical layer. Vhe DPCH is typically divided into dedicated physical data channel {DPuCIi; and dedicated physical control channel (DPCCH] both in the uplink and the downlink. Data such as the power control commands, transport format information, and dedicated piloc symlDols are transmitted en the D?CCH. Information such as diversity feedback infcrmaticn may also be transmitted on DPCCH in the uplink. The HS-DSCH may be mapped to one or several high speed physical downlink shared channels {!IS-PDSCH) in the physical layer.
The associated dedicated channel is tyPcally provided bo-h in the downlink and r.he upink. The dedicated channel is typically used to carry H3DPA related information/signalling as well as other dedicated data such as speecn and control data. The user equipment may com'tiunicate with several base

stations at the same time. For example, the associated dedicated channel may be in soft handover.
In addition to associated dedicated channels, che HS-D3CH may be associated also with a shax'ed control channel (3CCH) . The SCCH can be used to carry HS-DSCH specific
information/signalling to those users receiving data on uhe HS-DSCH.
A current proposal is to use the dedicated channel to inform the user equipment that it has data to be read on the HS-DSCH and SCCH. That in, only those users receiving data at a given time will receive an indication on the dedicated channel. The dedicated channel may be called as a pointer o^hannel since it points to the shared channels. The dedicated channel may also contain information about modulation and coding schs'iries, power levels and similar parameters used for che shared channels. This information can be sent also on the shared channel. The shared control channel on the other hand is used to carry information that is specific to the data t:ransmi:ted on the shared data channel (HS-DSCH) . This xafortnation can contain for instance packet numbers for the HARQ and so on. The shared control channel can be cent on a separate code channel (code multiplexed; or using the same code channels as llS-PDSCn (time multiplexed) .
Unlike the dedicated channel, the HS-DSCH is assumed noc to be in soft handover. That is, each base station is assumed ro have their own shared channel and the user equipment is assumed -c receive data from only one base station at a time. The so called fast cell selection (FCS) technique may be used

to swicch the data transmission from one base station co another. However, the shared channels does not use pov/er control. Instead, the shared channels are proposed to be nransmitced with fixed or seri-fixed pov/er. The Lena 'sen-.i-fixed' means in here than the power is not changed often. The power could, for instance, be a cell specific parameter.
In the currently proposed arrangements the high speed downlink shared channel iHS-D3CH) is planned to be associated with a dedicated channel which would carry in the downlink at least information regarding the timing when the receiving station is to receive on a shared channel. The associated dedicated channel may possibly carry also other information. In the uplink, the associated dedicated channel may carry, for example, the required acknowledgements (ACK) for a fast HARQ.
The inventor has found that chis may be problematic for examaple in the context of the uplink power control of the fasz HAEQ acknowledgements. A problematic situation may cccur especially when the associated dedicated channel is in the soft handorer mode. During the soft handover the uplink power is adjusted in accordance v;ith the best quality uplink among an active set cf base stations. However, signalling on the high speed shared channel may be transmitted from another bass station. The communication link between the user equipment and said other base station may be of poorer quality than said best uplink connection. Nevertheless, said ether rase station extects to receive responses such as an acknowledgement frorr. the user equipment. Since the quality of this uplink connection may be of substantially poorer q^jality than what the best uplink is, there is a risk that "he response is net properly received and decoded or is not received at all.

The fast cell selection function may be used to guarantee in some occasions that best possible downlink is utilised for communication towards the user equipment. However, the base station that provides the best uplink may be different than the base station providing the best downlink. This may be so, for example due to fast fading or other changes in the signalling conditions. This may increase the unreliabilizy of the responding functional ir.y.
The prior art proposals for solving this problem include so called strong coding, e.g., by using repetition coding. In the repetition coding the acknowledgcmcnt (ACK) bit or bits iS/are repeated several times. This, however, may cause too much additional load on the air interface and/or reserve too much of the radio resources if one wants to guarantee the correct reception of -he acknowledgement message.
Anouher prior art proposal is the so called fixed power offset for acknowledgement (ACK) transmissions. This cneans that all acknowledgement messages are transmitued with increased or a certain power in order to ensure that the acknowledgement is received ever, through the poorest quality uplink. However, even a fixed power level for acknov;ledgenent messages may not completely so_ve the prcolem of substantially poor signalling conditions. Thus situations v/here the pov/er is not high enough Tay still occur. On the other hand, it is also possible thaz the fixed power level is unnecessarily high. Thus, in addition to reliability problems this approach may be disadvantageous in that too high power is used by the user equipmsni causing incerference and unnecessarily high pov/er coiisumpLion.

Summary of the Invention
Embodiments of the present invention aim to address one or several of the above problems.
According to one aspect of rho present invention, there is provided a method for communication between a first station and a second station, comprising: ccmmunicatinf from the first station to the second station information associated -A-ith the manner how the second station should transmit towards the first station; and transmitting from the second station based on said information from said first station instead of transmitting in a manner the second station would have transmitted had it not been provided with said information.
In a specific embodiment said information is transmitted on a dedicated channel from the first station to the second station.
In another specific embodiment said mformation is communicated in a message that is transmitted from the first station to a second station, A response to the message is then transmitted from the second station based on said informatino.
The second station may transmit v/ith a transmission power that has been set based on said information after having received the information.
The second station may repeat the transmission, ths number of transmissions depending on said information.

Said information may define an offset parameter, the power level cf the transmission being shifted an amount as indicated by said offset parameter for the transmission.
In an additional step the quality of the interface between nhe firsr and second stations is determined. The information to be transmitted to the second station is then defined by the first station based on said determination.
The second station may be in communication with at least one further station, said further station providing control instructions to the second station. The second station may be involved in a handover between said at least two stations. The second station may bo in a soft handover mode.
According to another aspect of the present invention there is provided a communication system comprising: a station; a user equipment for communication with the station via a wireless interface, said user equipment being adapted to control at least one transmission parameter; and control means adapted for provis-cn said user equipment with information associated with a transmission parameter for use by the user equipment when transmitting to the station, the user equipment being enabled to transmit with a different trarnsmission parmeter based on said information than what the transmission parameter would be if the user equipment had not been provided with said information.
At least one further station may be provided, said furzher station being adapted for communication with the user equipment, the arrangement preferably being such that the U3cr equipment is adapted to follow control instructions from said further station unless said information is crcvided thereto.

According to another aspect of the present invention there is provided a station for a communication system ccrriprising ccncrol means for generating a message to be comrr.unicated from the station to another stacion, said control means being adapted to provide said other station with information associated with a parameter for use by said other station for use in control cf communication from said other s~ation to the station when responding the message.
According to another aspecc of the present invention there is provided a user equipment for communication with a stacion of a communication system via a wireless interface, comprising means for receiving a message from the station and control means for transmitting a response to the message, v;herein the user equipment is adapted to transmit the response in accordance with control information received with the message.
Brief Description of Drawings
For better understanding of the present invention, reference will now be made by way of example to the accompanying drawings in which:
Figure 1 shows an access system wherein the present invention may be embodied;
Figure 2 is a flowchart illustrating the operation of an embodiment of the present invention; and
Figure 3 shows a specific embodiment.
description of Preferred embodirrents of the Invention
An embodiment will now be described with reference to a mobile telecommunication system. The exemplifying communication

system comprises a radio access part adapted Lo operate based on the WCDI (Wideband Code Division Multiple Access) technique. A fearture of the WCDMA based systems is that a plurality of user equipment is allowed to communicate with a base transceiver station in a cell ever a radio interface (only one user equipment, however, is shown in Figure 1 for clarity) . As shown by Figure 3 , a user equipment is also allowed to be in radio communication with more than one base station at the same time. Figure 1 shows only two base stations BSl, BS2 for clarity.
The user equipment comprises a mobile station MSI. The term mobile station refers to a mobile user equipment that is enabled to move from a location to another. A mobile station may also roam from one network Lo another network, if the other network is compatible with the standard the given mobile station is adapted to and there is a roaming agreement between the operators of the two networks.
Each of the base stations BSl, 1232 may be provided v;ith a controller entity BCE. The controller entity may be adapted to perform various task, such as to measure and control power levels that are used for communication between the base station ard thr mobile station .YSl. In addition to the controller entity of the base staticn, the operation of the base station may also be controlled by at least one furthe-controller entity, such as a radio network controller NC. The arrangement is typically such the various control functions associated wich a base station are divided between the controller enzity of the base station and a network controller entity. A network controller entity nay be adapted to control one or several base stanicns. The various network controller

entities may be connected to each other for communication therebetween.
Communication between the mobile station and the base stations may comprise any kind of data such as speech data, video data or other data. The base stations and mobile station communicate also control data. The control data may associate with management operations. The control data may comprise messages such as various request and acknowledgements.
Data may be transmitted between the stations as a plurality of data symbols in subsequent data or radio frames. The signals carrying the data may be transmitted with variable data symbol transmission rates (data speeds) , wherein the transmissioa rate may be different in subsequent frames of the transmission. The data symbols may be transmitted based on different access techniques. For example, in the -ZDMA (Code Division Multiple Access) system data is encoded for transmission by processing data symbols to be transmitted by a spreading code for each transmission channel. In the TDMA. (Time Division Multiple Access) system data is transmitted in different time slots allocated fcr different channels.
The communication between che mobile station MSI and the base stations BSl and 3S2 may occur via different communication channels, such as via a dedicated channel, shared channel and 30 on. In some systens such as the CDXA the channels may be distinguished from cne another by the use of scrambling codes in a manner which is known by the skilled person.
In Figure 1 the different signalling conditions betv;een the mobile station and the base stations are illustrated by different widths of the arrows betv;een the stations. As shown.

base Ecaticn BSl has a weaker uplink with the mobile station MS1 than the other base station ES2. This implies that the power control of the uplink following the base station BS2. Hovjever, as shown in Figure 1, the downlink from base station BSl may be strcnger than what the downlink from the base station 3S2 is.
Each of the base stations of Figure 1 may be enabled to measure one or more paraneter that associate with the connection. The parameter may be a quality parameter such as the power levels or signal to interference (SIR) level in the uplink. That is, the power level or SIR level az which each base station BSl, BS2 receives from the mobile station MSI may be known by the respective base station.
The power control mechanism in the access network is typically such that the mobile station MSI follows the power commands received from the "strcngest" base station, e.g. the base station BS2 that receives the signal transmitted by MSI with the best quality parameter. The transmission power of the mobile station MSI is then adjusted accordingly even if the other base station BSl keeps on asking for more transmission power. This is so since the mobile station MSI only increases transmission power if all "hose base stations that are in soft handover with the mobile station MSI ask for more power.
In the following example it is assumed that in normal operation the mobile station MSI adjusts it transmission power based on the power commands received from the base station BS2. The power adjustment mechanism may be based on use of the so called quality target or power threshold values. If the quality of the connection is below the target value, the mobile station XSl is asked to increase the transmission power

and if the quality is above the target, the power is asked tc be decreased.
The connecuion quality target can be announced e.g. by means of so called Eb/No (Signal Energy/Noise) or SIR (Signal to Interference Ratio) or desired signal level carget or a similar param.eter indicating a quality measure v/hich can be estimated for the connection between two stations.
The quality of the connection is controlled based on the target value. Any of the connection parameters that have influence to the quality of the connection should follov; any changes in the target. In most cases it is sufficient if the transmission power is increased/decreased in order to meet the quality target value. A more detailed description of a possible closed loop power control mechanium can be found, for example, from 5GPP (third generation partnership project) technical specification No. TS25.214 "Fhysical layer procedures (FDD)".
In addition to the cloased loop power control mechanism the CDMA systems may includs also an outer loop power ccntrol mechanism. This nay adjust the power or SIR target based on other quality target parameters such as the bit error rate (BER) or frame error rate (FER) or any other similar quality target the connection should meet.
In che embodiments a first station may transmit data or a request or an enquiry tc a second statinn. After x-eception of said transmission the second station then transmits a response back to the first scacion. To improve the reliability and/or optimise -he use of resources, information associated with at least one parameter for the response is signalled from -he

first station to the second station, This parameter may, for example, associate with the required power levels of the response and/or the nunber of times the response shall be transmitted and so on. The response signalling is then performed based on the received information.
In the Figure 1 example the first station is the base station BSl and the second station is the mobile station MSI. For example, when the base station BSl allocates a channel to the mobile station MSI and sends data thereto on the high speed daua shared channel (KS-DSCH) , the base station BSl expects the mobile Gtation to return an acknowledgement (ACK),
The base station BSl may provide the mobile station with information on an associated control channel (either dedicated or shared) regarding the power levels required for the response. In = preferred embodiment the information provides the mobile station MSI with an offset value. The offset value indicates the difference in power relative to power level used for transmission in the best uplink with the base staticn 3S2 . The base station 3S1 determines the offset that is needed for the reliable acknowledgement transmission from the mobile station MSI based on one or more measurements associated with transmissions from -he mobile staticn. The power is determined such that a predefined level of reliabality is obtained for the decoding of the acknowledgement at the base staticn 3Si.
The mobile station r
that the response transmission needs to be accomplished m a different power level than what is used for communication with the best base station 3S2 and control the transmission accordingly.
The acknowledgement message (ACK) may be transmitted back to the base stativon BSl on a dedicated channel. The dedicated channel may be 'on' all the time even if there is no acknowledgements to be cent. This is so in order to keep the closed loop power control running. The active base station BSl may measure a quality parameter such as the signal to interference ratio (SIR) of this dedicated channel for overall power control purposes. This may be done e.g. based on so called pilot bits that are transmitted by the mobile station. Thus the case station BSl can calculate a required power offset. The power offset requirement is signalled from the base station BSl to the mobile station MSI with the downlink data packet to tell the mobile MSI how much more power is required for the acknowledgement transmission.
New signalling bits may be added in rhe downlink transmission from the base station BSl to tell the required power offset for the user equipment MSI. These bits may be sent, e.g., or. the shared contrcl channel since only the user equipment or those user equipment receiving on the downlink shared data channel need to send the acknowledgement ACK. That is, this information is not needed all the tine, but only when there is data packets to acknowledge. Alternatively, the base £tat.ion may sent these bits to the user equipment via a dedicated control channel or dedicated data channel.
The power control may be accomplished in a slot by slot basis in access techniques vherain the transnissions occur in slots.

A transmission can be dividea into the slots e.g. based on time or by means of a spreading code. The mobile station MSI may be adapted to assign power for the slots in accordance with a "normal" power control mechanism unless the mobile station has been provided with informiation which requires use of a different power Isvel for a slot (or several slots) that are allocated for the response.
Tn a simple naae one bit may be enough for the provision of the above referenced information. For example, ' C' could indicate that an offset of 5dB is required and '1' cculd indicate an offset of lOdB. According to another possibility '0' could indicate that no offset is required and '1' could indicate that a predefined additional power is required.
2 to 4 bizs may be used in a typical application for defining 4 to 16 different power offset levels. A step between the different power levels may be, for example, 2, 5 or 10 d3. Alternatively the step size between the power levels may be adapted to change nonlinearly.
A more specific embodiment vjill now be described with reference to Figure 3 shov;ing transmission of data packers between a base station (node B) and tv;o user equipment UEl and UE2. It shall be appreciated that although Figure 3 3hov;s channels in association with only one base station, a plurality of base stations may have communication channels with the user equipment UEl and/or UE2 at the same time. Otb«r channels are, however, not shown for reasons of clarity.
A number of packets is shov/n to be transmitted -ic a first user equipment UEl and to a second user equipment UE2 on the data channel HSPDSCH. The vertical lines of Figure 3 dividing the

transmission into secticns indicate a high speed dovmlir.k packet access trans-ission time intervals 'HSDPA TTI). The HSDPA TTI is a collection of a defined number of slots. That is, the high speed dovmlink packet access transmission time interval (TTI) defines a period for data transportation between user equinmFint and a base station via the high speed downlink shared channel (HSDSCE) . Logically the TTI can thus be seen to correspond the concept of data frames. In the Figure 3 example eight TTIs arc shown, each '-TI being three slors in length.
In the following it is assumed that the acknowledgements are provided in accordance with the fast hybrid automatic repeat request (HARQ) scheme. A so called K-channel HARQ is also assumed tc be used for the tast HARQ together with a so called stop-and-wait protocol. The stop-and-wait protocol may be used in order to reduce buffering requirements of the receiving staticn.
The N-channel HA?.Q supports asynchronDus transmission. Thus different users can be scheduled freely without need to waiu for completion of a given transmission. The receiving station may need, however, to know to which KARQ process the packer belongs to. This information can be explicitly signalled on a high speed do^vnlink packet access (HSDPA) control channel iCH) , e.g. che SCCH. For example, after three packets have been cransporzed to the first user equipment USl, two packets may be transmitted to the second user equipment: UE2. The transmission co the first user equipnenc L'El may in such case be delayed by two TTIs. The processing nimes of data packet to different user equipment should be defined such that continuous transmission co a user equipment is possible.

Each packet is preferably acknowledged during the transmission of ether packets so that the downlink (DL) channel can be kept occupied all the time when there are packets no be transmitted.
In Figure 3 the uplink acknowledgements are shown to be transmitted on the dedicated physical control channel (DPCCH). Arrov/D Rl to R9 indicate various relations between different operations. That is, relations between pointer bits on the DL npCF, shared data and control channel (HS-PDSCH and SCCK] cransmission and the acknowledgement transmissions.
More particularly, each of the double lined arrows R2, R5 and R9 indicates a quality mcasurement performed for the uplink of a given user equipment en the respective dedicated control charjiel. The single lined arrows Rl, R4 and R6 indicate the relationships between the pointer bits and shared control channel SCCH in the downlink. The single lined arrows R3 and R6 indicate the relationships between the dcwnlink data channel HSPDSCH and acknowledgements in the uplink. The acknowledgements are transmitted with a power that has been adjusted based on information received on the SCCK, that is based on the results of the measurements.
During the first interval TTIl the base station transmits a pointer bit to the user equipment UEl. The pointer hit indicates that the user equipment UEl shall receive data and control information during the next TTI (TTI2) on the HS-PDSCH and on the SCCH. Also during TTIl, the base station measures the quality of the uplink of the user equipment UEl. These

relations are shown by the relation arrows Rl and R2, respectively'-.
For example, the GIR of the uplink can be measured from the dedicated pilot symbols -ransmit-ed on the DPCCH in every slot. Based on chis cjuality measurement, the base station provides the user equipment UEl in the TTI2 with information regardip.g the power level that should be used whan transmitting the acknowledgement during TTI4. This relation is indicated by arrow R3. The power level information can be provided as a power offset, as explained above. Ibis power offset information may be, for example, provided as a field of a fev/ bits in the shared control channel (SCCH) .
It should be noted that the ncasuremencs may be averaged over a longer period of time or othcrwioe processed. the arrow R2 simply shews chat the power offset used for the transmission is based on the measurement (s) done before the transmission of the power offset.
After having received the power level information the user equipment USl sends the acknowledqement using a power level chat is based on informationi from the base station. The acknowledgement may be a positive acrznowledgement (A in Figure 5} or a negative ackncv/ledgemenc (N ir. Figure 3) .
In Figure 2, some of the acknowledgement slots are shewn to be higher in order to illustrate that increased transmit power is used for" these acknowledgements. The increased power may be applied for the whole slot or only on the acknowledgement bits within the slot. The same incr-eased power may also be used in

other clots it they contain other information such as measurement or quality report which is senc only to the same base station as rhe acknowledgeTrp.nr.. The increased power may also be applied to the entire TTI or even a number of TTIs .
In addition to relations Rl to R3, Figure 3 illustrates also a second set of relazions R4 to R9 that associate with the user equipment UE2. In this case the acknowledgement was negative (N) and thei-efore a new pointer bit was given on the DTi CFCK channel of the second user equipment UE2 for retransmission of the message.
In order to ensure that the power level for the response can be determined appropriately by the base station the uplink quality measurement is preferably accomplished as late as possible. As shown, information asscciated e.g. with the neasurement as indicated by the arrcw R2 is transmitted in the next transmission time incerval (TTI2) on the control channel (DLSCCII) .
The embodiments are especially suitable for acknowledgements because the acknowledgements need to be cent in response to a downlink transmission and also because the reliability of the acknowledgement transmission should be high.
The message specific control information may be signalled only when the f'.rst station determines that a different parameter is needed in order to ensure a reliable response by the user equipment.
Figure 4 shows a further embodiment m which thr user equipment first follows power commands from the strongest

base station, that is from a base station 3S2. Another basa station B51 sends a power offsetl' message to the user equipment. After having received the 'power offsetl' message the power control function of the user equipment s::arts to follow said other base station.
The user equipment power control nay set ics transmission power based on the message from the base station BSl for a predetermined time. The user equipment may alternatively follow the commands from the base station BSl as long as it has some information, such as acknowledgements or measurement reports or so on to be sent to this base station. The user equipment may also wait for new power offset information from any of the base stations it is in connection v/ith. That is, a new offset such as the shown *0ffset2' will replace the previous offset parameter.
' When the user equipment power ccntrcl returns to the "normal" soft handover mode the user equipment may change (typically decrease) its power back to the level it used before receiving the offset command Of.setl ' . That is, the user equipment may start to follov; the power control commands from the strongest base station 3S2 having the bcst uplink with the user equipment:. This may be accomplished by using offset parameter that equal with the first offset (i.e. offset2=offsetl in Figure 4) informed by the base station BSl or a predetermined second offset (offset2). The second offset may be a function of the said first offset. The second offset may also be informed by the base station BS2 having the best upl.nk.
In a further embodiment each base station in connection (for instance, in a soft handover) with the user equipment may continuously measure the quality of the uplink. Ir. addition to

or instead of the normal power control commands each of the base stations may send power offset information to the user equipment telling how much the power should be changed (increased or decreased) in order to meet the quality target. This information is preferably sent on the dedicated control channel. In a normal soft handover case zhe user equipment may then use the offset that results in the lowest transmission power or alternatively tollow the normal pov/er control commands. However, when the user equipment has something to send to one base station only, the user equipment may then use the power offset sent by that base station. The offset may be sent periodically, e.g., in each clot as the power control commands, or once per every n slots and so on. The offset information may also be sent when needed, e.g., when the value of the offset exceeds some threshold values.
In an embodiment the user equipment may also be forced to use stranger coding for the transm.ission of the acknowledgement message. For example, the user equipment may be instructed tc transmit the acknowledgement repeatedly. For example, instead of sending the acknowledgement once the user equipment may be instructed to transmit the acknowledgement three, five, or ten times and so on. According to an embodimenc the user equipment is instructed to transmit che acknowledgement e.g. in three slots instead of one slot so chat the acknowledgement can be decoded reliably.
The above discussed transmission parameter information provision mechanism may also be used in connection with ether signalling functions than acknowledgemencs. The response messages could be, for example, measurement reports or other reports. The herein proposed signalling mechanism may be especially advantageous if a report is requested by a base

station of a plurality of base stations in communnication with a user equipment. The base station may inform the user equipment of the power offset and/or any other parameter that is to be used for the response towards the specific base station.
The above discussed adjustment of at least one feature of the response signalling based on information from power level measurements. The adjustment may also be based on other information that associates v;ith the interface between the two stations. For example, the base station BSl may request for a certain power offset based on analysis of the previous responses from the mobile station MSI. If the analysis indicates that a certain number of responses has net been correct, the offset may be increased in order to improve the reliability. The responses may be earlier ACKs or other data-transmitted from the user equipment, e.g., speech packets.
It is noted that the above disclosed solution is applicable also in instances where the first message is sent from the user equipment to a base station. In such a case the user equipment may inform the base station of any requirements chat it may have for the response from the base station.
It shall be appreciated that whilst embodiments of the present invention have been described in relation to mobile stations, embodiments of the present invention are applicable to any other suitable type of user equipment.
It shall be appreciated that whilst embodirents of the present invention have been described in relation to a mobile station that is in communication with more than one base station, the present invention is applicable also to instances where only

two station are in communication with each ether. For example, a first scation transmitting a message that is to be respcnded by a sftnond station may insert in the message information regarding e.g. coding and/or power that is to be used for responding to the particular packet.
It shall be appreciated that while this specification mentions some system specific examples of the communicacior. channels the embodiments of the invention are noz restrictsd by tnese examples.
The rcsponse may also be sent, for example, on a shared control channel or a data channel in systems where such a channel is defined. P. specific acknowledgement channel may also be defined.
The data is described as being in packet form. In alternative embodiments of the invention the data may be sent in any suitable forma-:.
In addition, it is net always necessary to measure the quality of the connection for each data packet and/or to provide the user equipment with the offset information each time a response is required. Instead, the measurement may be accomplished and/or information transnitted e.g. in predefined intervals or in response to a predefined event (e.g. the quality of the connection has changed cr tne user equipment has been relocated from a network controller to another network controller and sc on) , It may thus be enough if the offset information is provided once for the user equipment during a connection between the user equipment and a base station.

The en±:cdiment of the present invention has been described in the context of a CDMA system. This invention is also applicable to any other access techniques including time divisicn multiple access, frequency division multiple access or space division mulultiple access as well as any hybrids thereof.
It shall be appreciated that the base station may in some communication standards, such as those associated with the 3^^ generation (3G) universal mobile telecommunications system (UMTS) , be referred to as node 3. Hov/ever, this specif icacion has used the term base station for clarity.
According to an alternative solution for the above discussed problem a dedicated physical channel (DPCK) is used only in association with a high speed downlink shared channel (HS-DSCH} . That is, no ocher data is transmitted on the DPDCH. The pcwsr control of the DPCH may then follow base sea-ion that transmits on the active IIS-DSCH (both in the uplink and che downlink) instead of the best base station. If no other daza is transported on the uplink DFDCH, then the uplink power control function of the m.obile station could follow Lhe active high speed da-a base station. In such a situation informaLion regarding the power ortset may not be needed for the uplink, since the pov;er control function may adjust the power.
It is also noted herein that while the above describes exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution withcut departing from the scope of the present invention as defined in the appended claims.

Claims
1. A nsthod for communication between a first, station and a
second station, comprising
ccmrr.unicating from the first station to the second station information associated with the manner how the second station should transmit towards the first station; and
transniting from the second station based on said information from said first station instead of transmitting in a manner the second station would have cransmitted had it not been provided with said information.
2. A method as claimed in claim 1; wherein said information is transmitted on a dedicated channel from the first station to the second station.
3. A method as claimed in claim 2. wherein the transmission of said intormation is periodic.
4. A method as claimed in claim 1, wherein said information is communicated in a message transmitted from the first station to a second station, and wherein a response to the message is transmitted from the second station based on said information.
5. A method as claimed in any preceding claim, wherein the second station cransmits with a transntissica power chat has been set based on said information.
6. A method as claimed in any preceding claim, wherein the second station repeats the transmission cf the response, the numoer of the transmission depending on said information.

7. A method as claimed in any preceding claim, wherein said information defines an offset to a power level paramezer, and wherein the power level cf the transmission is based on said offsat.
8. A method as claimed Ln claim 7, wherein the predefined power level is defined by a connection quality threshold paraT.eter.
9. A method as claimed in any preceding claim, wherein said information is transmitted from the first station to the second station on a control channel,
10. A method as claimed in claim 9 when dependent on claim 1 or any of claims 4 to 3, wherein said control channel is a shared channel.
11. A method as claimed in claim 9, wherein said control channel is a dedicated control channel.
12. A method as claimed in claim 4 nr any claim dependent on claim 4, wherein the response is transmitted on a dedicated data channel.
13. A method as claimed in claim 4 or any of claims 5 to 11 when dependent on claim 4, wherein the response is transmitted on a dedicated control channel.
14. A method as claimed in claim 4 or any of claims 5 to 11 when dependent on claim 4, wnerein tne response is transmitted on a shared control channel.

15. A method as claimed in claim 4 or any of claims 5 to 11 when dependent on claim 4, wherein the response is transmitted on a shared data channel.
15. A method as claimed in. claim 4 or any claim dependent on claira 4, wherein the response comprises an acknowledgement.
17. A method as claimed in any preceding claim, wherein the transmission from r.he Bficond station comprises a report requested by the first station.
18. A method as claimed in claim 17, v/herein the report comprises a measurement report or quality report.
19. A method as claimed in any preceding claim, comprising determining the quali-y of the interface between the first and second stations, and defining the infcrmaticn to be transmitted to the Decord staticn based on said determination.
20. A trerhod as claimed in claim 19, v/herein step of determining comprises measuring signal to interference ratio cr a power level of the interface from the second station to the first station.
21. A method as claimed in claim 19, wherein step of determining comprises deterrr.ining the rate of successful and/or unsuccessful responses or transmissions from the second station at the first station.
22. A method as claimed in claim 4 or any claim dependent on claim 4, wherein the message comprises at least one data packet.

23. A method as claimed in claim 4 or any claim dependent on
claim 4, wherein the message and response procedure is based
on a hybrid automatic repeat request scheme.
24. A method as claimed in any of claims 1 to 2; comprising returning the second station into a mode where it transmits in accordance with usual transmission procedures of the communication system the stations belong to.
25. A method as claimed in any preceding claim, wherein the first station comprises a base station cf a cellular communication system.
26. A meuhod as claimed in any preceding claim, wherein the snccnd station coaiprises a mobile user equipment.
27. A method as claimed in claim 25 cr 26, wherein the station communicates based on the code division multiple access mode.
28. A method as claimed in any preceding claim, wherein the second station is in communication with at least one further station, said further station also providing control instructions to the second station.
29. A method as claimed in claim 28, wherein the second station is involved in a handover between said at least two stations.
30. A method as claimed in claim 29, wherein the second station is in a soft handover mode.
31. A ccmmunication sysiem comprising:

a station;
5 user equipment for communication with the station via a wireless interface, said user epuipmcnt being adapted to contrcl at least one transmission parameter; and
control means adapted for provision said user equipment with information associated with a transmission parameter for use by the user equipment when transmitting to the station, the user equipr.ent being enabled to transmit with a different transmission carameter based en said information than what the transmission parameter would be if the user equipment had not been provided with said information.
32. A communication system as claimed in claim 31, comprising at least one further station adapted for communication with the user equipment and v/herein the user equipm.ent is adapted to follow control instructions from said other station unless provided wi-h said information.
23. A communication system as claimed in claim 31 or 32. comprising means for generating a message to be transmitted from the station to the user equipment, and wherein the user equipment is adapted to transmit a response to the message based on said information.
34. A station for a communication system comprising control means for generating a message to be communicated from the station to another station, said control means being adapted to provide said other station wich information associated with a parameter for use by said other station for use in control of cornmunication from said other station to the station -when responding the message.

35. A user equipment for communication with a station of a communication system via a wireless interface, comprising:
means for receiving a message from the station;
control means for transmitting a response to the message, wherein the user equipment is adapted to transmit the response in accordance with control information received with the message.

36. A method for communication, substantially as hereinabove described and illustrated with reference to the accompanying drawing.

Documents:

1515-chenp-2003 abstract granted.pdf

1515-chenp-2003 claims granted.pdf

1515-chenp-2003 description (complete) granted.pdf

1515-chenp-2003 drawings granted.pdf

1515-chenp-2003-claims.pdf

1515-chenp-2003-correspondnece-others.pdf

1515-chenp-2003-correspondnece-po.pdf

1515-chenp-2003-description(complete).pdf

1515-chenp-2003-drawings.pdf

1515-chenp-2003-form 1.pdf

1515-chenp-2003-form 18.pdf

1515-chenp-2003-form 26.pdf

1515-chenp-2003-form 3.pdf

1515-chenp-2003-form 5.pdf

1515-chenp-2003-pct.pdf

« Previous Patent

Next Patent »

Patent Number

225833

Indian Patent Application Number

1515/CHENP/2003

PG Journal Number

02/2009

Publication Date

09-Jan-2009

Grant Date

01-Dec-2008

Date of Filing

26-Sep-2003

Name of Patentee

NOKIA CORPORATION

Applicant Address

Keilalahdentie 4, FIN-02150 Espoo

Inventors:

#	Inventor's Name	Inventor's Address
1	MALKAMAKI, Esa	Riippakoivuntie 17B, FIN-02130 Espoo

PCT International Classification Number

H04B 7/00

PCT International Application Number

PCT/IB2002/002035

PCT International Filing date

2002-03-28

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	0107746.0	2001-03-28	U.K.