Title of Invention	CHANNEL ESTIMATION AND CHANNEL QUALITY INDICATOR (CQI) MEASUREMENTS FOR A HIGH SPEED DOWNLINK GPRS
Abstract	An appratus for providing a Time Division Multiplexing (TDM) scheme for link adaption including use of channel estimation and Channel Quality Indicator(CQI) measurements by bundling several timeslots of a frame within the existing GSM/GPRS/EDGE System. An algorithm for providing roation of MS users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission of information.

Title of Invention

CHANNEL ESTIMATION AND CHANNEL QUALITY INDICATOR (CQI) MEASUREMENTS FOR A HIGH SPEED DOWNLINK GPRS

Abstract

An appratus for providing a Time Division Multiplexing (TDM) scheme for link adaption including use of channel estimation and Channel Quality Indicator(CQI) measurements by bundling several timeslots of a frame within the existing GSM/GPRS/EDGE System. An algorithm for providing roation of MS users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission of information.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10, rule 13) “Channel Estimation and Channel Quality Indicator (CQI) Measurements for a High Speed Downlink GPRS" QUALCOMM INCORPORATED, an American company of 5775 Morehouse Drive , San Diego, California 92121-1714, United States of America The following specification particularly describes the invention and the manner in which it is to be performed. WO 2005/117464 PCT/US2005/015049 CHANNEL ESTIMATION AND CHANNEL QUALITY INDICATOR (CQI) MEASUREMENTS FOR A HIGH-SPEED DOWNLINK GPRS BACKGROUND Field \|00011 The present invention relates to wireless communication systems generally and specifically to scheduling data transmissions in a Global System for Mobile communications referred to as GSM. Background [0002J The Global System for Mobile communications (GSM) wireless telecommunications standard defines a set of widely available digital communications protocols for use within a digital wireless telephone system. The GSM specifications are developed by an international effort and adopted by the European Telecommunications Standard Institute (ETSI, 06921 Sophia Antipolis Cedex, France). The General Packet Radio Service (GPRS) is a set of new GSM bearer services that provides high-speed packet-mode transmission within the Public Land Mobile Network (PLMN) and towards external networks. And, the Enhanced Data rates for a Global Evolution (EDGE) were introduced to improve circuit switch and packet switch GSM data services. At the time of inception of the GSM/GPRS/EDGE standard, which supports voice and high rate packet data services, the use of Time Division Multiple Access (TDMA) within the GSM/GPRS/EDGE Over-The-Air (OTA) protocol increased the efficiency with which the given radio frequency bandwidth could be used to conduct wireless telephone calls. Even increasing services and demand require efficient ways of providing system resources to more and more data users. There is a need, therefore, to provide high speed data transmissions in a GSM/GPRS/EDGE environment. SUMMARY [0003] The embodiments disclosed herein address the above stated needs by providing an apparatus that provides a Time Division Multiplexing (TDM) scheduling scheme including use of channel estimation and Channel Quality Indicator (CQI) measurements WO 2005/117464 PCT/US2005/015049 3 by bundling several timeslots of a frame within the existing GSM/GPRS/EDGE framework. [0004] One embodiment provides an apparatus, in a wireless communication system supporting voice and high packet data services, which performs channel estimation, determines a Channel Quality Indicator (CQI) index, and returns assignment/data information based on the CQI index. According to this embodiment, an algorithm enables rotation of Mobile Station (MS) users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission of information. BRIEF DESCRIPTION OF THE DRAWINGS [0005] The invention is illustrated by way of example and not limitation and the figures of the accompanying drawings in which like references denote like or corresponding parts, and in which: [0006) FIG. 1 is a block diagram of a cellular telephone system configured in accordance with the GSM/GPRS/EDGE standards. (0007) FIG. 2 is a diagram illustrating the case of voice services being sent on timeslot 1 of the transmitting unit (Tx) frame and being received on timeslot 1 of the receiving unit (Rx) frame viewed from the base station. [0008] FIG. 3 is a diagram illustrating the case of high speed circuit switch data being sent on timeslots 1 and 2 of the transmitting unit (Tx) frame and being received on timeslot 1 of the receiving unit (Rx) frame viewed from the base station. [0009] FIG. 4 is a diagram illustrating the case of high speed circuit switch data being sent on timeslots 1,2,3, and 4 of the transmitting unit (Tx) frame and being received on timeslots 3 and 4 of the receiving unit (Rx) frame viewed from the base station. [0010] FIG. 5 is a diagram illustrating the case of high speed packet data being sent on timeslots 1 and 3 of the transmitting unit (Tx) frame and being received on timeslot 2 of the receiving unit (Rx) frame. [0011] FIG. 6 is a diagram of the received power in a MS with respect to time. [0012] FIG. 7 is a diagram of the CQI for two mobile stations, with respect to time. [0013] FIC 8 is a block diagram illustrating the assignment and data sent to the MS based on the CQI received by the BS. WO 2005/117464 PCT/US2005/015049 [001 4] FIG. 9 is a diagram illustrating for each frame, the assignment and data sent to the particular MS based on the CQI received by the BS. [0015] FIG. 10 is a diagram demonstrating the assignment and data information being sent on parts of a frame. [0016] FIG. 11 is a flowchart illustrating an algorithm for rotating the position of users on a frame such that each user will benefit from measuring all timeslots of the frame resulting in better channel quality. [0017] FIG. 12 is a diagram illustrating the position of the MS users after performing the algorithm of rotation of FIG. 11. [0018 ] FIG. 13 is a diagram showing the bundling of several timeslots into one channel. [0019] FIG. 14 is a diagram demonstrating timeslots containing midambles used for channel estimation and CQI reporting. DETAILED DESCRIPTION \|002O) The word "exemplary" is used exclusively herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the present invention are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated. [0021J The present invention relates to bundling several timeslots of a frame together in order to estimate a channel's quality and to send assignment and data information to the mobile station (MS) with a good channel quality within the existing GSM/GPRS/EDGE system. One embodiment also provides an algorithm which enables rotation of MS users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission. In a high rate packet data system, upon receipt of the paging messages from one or more base stations, the MS measures the Signal-to-Noise-and-Interference Ratio (SNIR) of the forward link signals and sends a Channel Quality Indicator (CQI) to the Base Station (BS) at each frame or bundle of timeslots. This BS, in turn, sends assignment/data information to the MS which has good channel quality. [0022] The following discussion develops the preferred embodiment by first presenting a system supporting a GSM/GPRS/EDGE system. Next, a TDM scheduling scheme for link adaptation is introduced. Then the TDM scheduling scheme, which includes use of WO 2005/117464 PCT/US2005/015049 channel estimation experienced by each mobile station and which may be used by the scheduler to optimally allocate the radio resources is explained. Finally, it is helpful to discuss how this TDM scheduling scheme may be implemented into the GSM/GPRS/EDGE system and provide the above-mentioned benefits. [0023] Note the embodiments are provided as exemplars throughout this discussion; however, alternate embodiments may incorporate various aspects without departing from the scope of the present invention. Specifically, the present invention is applicable to a data processing system, a wireless communication system, a unidirectional broadcast system, and any other system desiring efficient transmission of information. Global System for Mobile communications (GSM) \|0024] The Global System for Mobile communications (GSM) wireless telecommunications standard is set of widely available digital communications protocols for use within a digital wireless telephone system. The GSM specifications were developed by an international effort and have been adopted by the European Telecommunications Standard Institute (ETSI, 06921 Sophia Antipolis Cedex, France). The General Packet Radio Service (GPRS) is a set of new GSM bearer services that provides high-speed packet-mode transmission within the PLMN and towards external networks. And, the Enhanced Data rates for a Global Evolution (EDGE) was introduced to improve circuit switch and packet switch GSM data services. A wireless telephone system configured in a manner consistent with the use of the GSM/GPRS/EDGE standards is shown in FIG. 1. GSM Mobile-services Switching Center (MSC) 16 switches or connects telephone calls between the wireless system access network, namely the Base Station Subsystems (BSS) 15, and wireline based Public Switched Telephone Network (PSTN) 18, which may also be a Public Land Mobile Network (PLMN). GSM MSC 16 provides telephone switching, billing, subscriber unit tracking, subscriber unit authorization, and some handoff control functionality. [0025] BSS 15 is comprised of base station controller (BSC) 14 and any base transceiver station(s) (BTS) 12 coupled thereto. As defined in the GSM specifications, the interface between GSM MSC 16 and BSS 15 is referred to as the GSM "A or Iu-CS interface," which separates the GSM/GPRS/EDGE network switching equipment from the Time Division Multiple Access (TDMA) based radio equipment. BSC 14 is WO 2005/117464 PCT/US2005/015049 6 involved with handoff processing and signal processing resource allocation within BTSs 12 so that multiple subscriber units 10, also referred to as Mobile Stations (MSs), can conduct telephone calls simultaneously. BTS 12 interfaces the subscriber units 10 via radio frequency (RF) signals and a well defined OTA protocol to the GSM/GPRS/EDGE wireless network. BTS 12 comprises radio transmission and reception devices, up to and including antenna devices, and also all the signal processing specific to the radio interface. BTSs can be considered as complex radio modems. Subscriber unit MS 10 provides radio and processing functions to access the GSM/GPRS/EDGE network through the radio interface to either the user of subscriber unit 10 or some other terminal equipment, such as a facsimile machine or personal computer. A particular subscriber unit MS 10 may switch the BTS 12 with which it interfaces as its location changes, but can only communicate with one BTS 12 at a given instant. Within this application, the capability to switch from one BTS 12 to another BTS 12, where only one radio interface exists at any instance, is referred to as subscriber unit hard handoff. [0026] To make a wireless telephone call, a network connection must be established between subscriber unit 10, often referred to as a "mobile unit," and PSTN 18. PSTN 18 is the CONVENTIONAL wireline telephone system. To conduct the telephone call in a mobile fashion, a portion of the network connection is formed via the exchange of Radio Frequency (RF) signals between subscriber unit 10 and BTS 12. The remaining portion of the network connection is typically formed through wire-based connections that pass through BSS 15 and through GSM MSC 16. In accordance with the GSM/GPRS/EDGE OTA protocol, which is one of the protocols that make up the GSM/GPRS/EDGE wireless telecommunications standard, TDMA technology is used to establish a set of channels within the above identified RF signals used to interface a subscriber unit 10 with a BTS 12. These channels are used to separate and distinguish the various sets of data associated with the various telephone calls being made at any given time. The various sets of data include user data which normally takes the form of digitized audio information, and signaling data which is comprised of the signaling messages used to orchestrate the processing of a telephone call. [0027] At the time of the inception of the GSM/GPRS/EDGE standard, the use of TDMA within the GSM/GPRS/EDGE OTA protocol increased the efficiency with which the given radio frequency bandwidth could be used to conduct wireless telephone WO 2005/117464 PCT/US2005/015049 calls with respect to older analog cellular systems. Increasing the efficiency with which the available radio frequency bandwidth i5 used is desirable because only a limited amount of RF bandwidth exists, and the amount of bandwidth is usually the limiting factor as to the number of calls that can be conducted by a particular wireless cellular telephone system. Since the inception of the GSM/GPRS/EDGE wireless telecommunications protocol, however, other wireless technologies have been perfected that allow a greater number of telephone calls to be conducted in a given RF bandwidth. Since efficient use of radio frequency bandwidth is highly desirable, the use of these more efficient technologies is now preferred. The GSM/GPRS/EDGE system supports transmission and reception of voice, high speed circuit switch data and high speed packet data. [0028] FIG. 2 is a diagram illustrating voice data sent on timeslot 1 of the transmitting unit (Tx) frame 20. Note that transmission and reception of information are viewed from the Base Station (BS). Since voice data has to be transmitted and received on the same timeslot, this data will be received on timeslot 1 of the receiving unit (Rx) frame 25. One frame 20 is made up of eight timeslots. Note timeslot 30 is identified for clarity. An architectural offset of three timeslots between the Tx and the Rx is required because the data cannot be transmitted and received at the same time. That is, the data is received on frame 25 with an offset of three timeslots. The information is received in the same order sent. This offset includes at least one timeslot 30 to allow for transition between transmission and reception of the data. The BS notifies the MS of the assignment of the timeslot receiving data. The upper layer signaling in the BS enables reservation of the timeslot. [0029] FIG. 3 is a diagram illustrating high speed circuit switch data sent on timeslots 1 and 2 of the transmitting unit (Tx) frame 35. The high speed circuit switch data, which uses timeslots, will be received on timeslot 1 of receiving unit (Rx) frame 40. Again, eight timeslots form a frame 35 and an offset of three timeslots between the Tx frame 35 and the Rx frame 40 is used because the data cannot be transmitted and received at the same time. Usually only one timeslot, i.e. timeslot 45, is used for transition between the transmission and reception states. This configuration enables more flexibility since the data is spread over two timeslots for transmission of data and spread over one timeslot for reception. Note that this configuration is unnecessary when voice is sent because the number of additional timeslots does not affect the quality of transmission or WO 2005/117464 PCT/US2005/015049 systems employing such an offset. Timeslot 75 is used to switch from transmission to reception. As observed in FIG. 5, timeslots on the BS Tx frame 65 that are used for transmission need not be consecutive since dynamic sharing is allowed between users. The upper layer signaling in the BS makes an assignment where it selects a pool of MS users. Then, with the help of in-band signaling, it makes an allocation where it selects a single MS user in the pool of users. This assignment is not permanent since it is performed on a frame by frame basis. [0032] As mentioned above, FIG. 1 demonstrates the interaction between the various components of the GSM/GPRS/EDGE system. The MS 10 differs in many ways from the MS for voice and circuit data services described above. The MS 10 has multi-slot capability which allows increased flexibility and capability. For example, significant differences in the maximum number of slots that can be used for sending/receiving data and in the minimum number of slots separating reception/transmission can be observed. The Serving GPRS Support Node (SGSN) 95 is the node that is serving the MS 10. The SGSN 95 establishes a mobility management context containing information pertaining to mobility and security for the MS 10. The SGSN 95 also collects charging information. The Gateway GPRS Support Node (GGSN) 90 is the node that is accessed by an external packet data network, via the Gb-interface. Routing information stored in the GGSN 90 is used to tunnel user data to the MS 10's current point of attachment, i.e. the SGSN 95. The GGSN 90 also collects charging information. In a conventional GSM/GPRS/EDGE system, a scheduler that determines the timeslot to be used by each terminal is located in base station controller (BSC) 14. As will be described below, in the present invention, the scheduler is located in the base station (BTS) 12 to provide for fast scheduling. (0033J In FIG. 6, the power received at the MS 10 is plotted against time. A fade margin, which represents fading of the channel, can be calculated between the highest point of power 105 and the lowest point of power 110. Since this fade margin becomes much smaller in a TDM scheduling scheme described below, it is beneficial to use this known technique within the existing GSM system in order to improve system performance and signal quality. WO 2005/117464 PCT/US2005/015049 TDM Scheduling Scheme For Link Adaptation [0034] In accordance with the embodiment of the data communication system of the present invention, downlink data transmission occurs from one BTS 115 to one MS 125 (see FIG. 8) at or near the maximum data rate which can be supported by the downlink and the system, including the possible use of higher order modulation (8PSK) that allows higher data rates in EDGE. Uplink data communication can occur from one MS 120 to one or more BTS 115. Data is partitioned into data packets being transmitted over one or more timeslots. At each frame or multislot, the BTS 115 can direct data transmission to any MS 120,125 which is in communication with the BTS 115. (0035] Initially, each MS 120, 125 establishes communication with a BTS 115 using a predetermined access procedure. In this connected state, the MS 120,125 can receive data and control messages 127 from the BTS 115, and is able to transmit data and control messages 127 to the BTS 115. The MS 120,125 then monitors the down link for transmissions from the base stations in the active set of the MS 120, 125. Specifically, the MS 120, 125 measures the signal-to-noise-and-interference ratio (SNIR) of the down link pilot from the serving base stations, as received at the MS 120, 125. Depending on the received SNIR, the MS 120, 125 will send a Channel Quality Indicator (CQI) back to the BTS 115. As shown in FIG. 7, each MS 120,125 will send a CQI to the BTS 115 at each time frame. [0036] As illustrated in FIG. 9, at each frame, MSI and MS2 will each send a CQI to the BS. Based on these two parameters, the BS will in turn choose a MS based on an internal algorithm that takes into account, among other factors, the CQI reports from all mobile stations and it will transmit a assignment information, such as within a header, to the selected MS. The BS will also send data to this MS at a slightly later time, as shown in FIG. 8. Implementation of TDM Scheduling Scheme For Link Adaptation In a GSM/GPRS/EDGE system [0037] HSD-PRS (High Speed Downlink GPRS) allows the bundling of several timeslots in order to create a Data Optimized/ Data Voice (DO/DV) like shared channel. As such, HSD-PRS introduces concepts such as fast feedback, fast CQI reporting, and so forth, within the existing GSM/GPRS/EDGE framework. Channel estimation and WO 2005/117464 PCT/US2005/015049 CQI measurements are an important process in HSD-PRS since the optimal allocation of the downlink resources is based on them. \|0038) As demonstrated in FIG. 13, HSD-PRS bundles together several timeslots into one channel, which is then directed towards a single user. All terminals will be able to receive those timeslots and read the header. The header indicates which, among the terminals sharing the HSD-PRS channel, is the intended recipient. The receiving terminal must read the data part, whereas all the other terminals can read none, a portion, or all of the data part. 100391 For the purpose of reporting, the important part of a timeslot is the midamble, as shown in FIG. 14. Every timeslot contains a midamble or center point. The MS uses the midamble for channel estimation and CQI measurements. Consequently, every terminal will read a certain number of timeslots within a TDMA frame of the HSD-PRS channel. It will then average the measurement and estimation performed over each of the timeslots. This average will be more accurate if the terminal has been reading all the downlink timeslots. The accuracy of such reporting can therefore be included in the report itself, so that the network can weigh the reports accordingly. The reports, together with the weights, will be used by the network to perform fast scheduling of the terminals. \|0040] If the transmit power changes dramatically from slot to slot, the CQI reporting may be affected and the base station would have to adjust its scheduling accordingly. In such a case, the mobile station should report which slots were considered in the estimate of the CQI, so that the base station can compensate for the CQI value with an offset, which may be a function of the transmit power in each of the slots that were used by the mobile station for the CQI estimate. [0041] Reporting is a fundamental part of HSD-PRS. The network will perform a fast scheduling of the downlink resource based on such reporting. Fast scheduling takes place on a TDMA frame basis. It includes both the decision of which user is the recipient of the information sent on that TDMA frame, as well as the coding and modulation parameters. Since the HSD-PRS spans over multiple timeslots within a TDMA frame, the corresponding uplink timeslots can be used for reporting. Reporting is based on channel estimation. This is in turn performed by the terminals on the midambles transmitted on the downlink. WO 2005/117464 PCT7US2005/015049 12 (0042) As described in the previous section, a design choice has been done to prevent the terminals from having to transmit and receive at the same time. Due to the GSM offset of three timeslots between transmitting and receiving, it is possible to achieve this. However, some of the terminals will have to interrupt the channel estimation early in order to start transmitting on the uplink. One timeslot of separation is needed between the reception and transmission if the mobile station does not support simultaneous reception and transmission, which is the most common case. [0043] By implementing the allocation of CQI and fast scheduling offered by the TDM scheduling scheme into GSM, it is possible to obtain a more advanced system with increased capacity. As shown in FIG. 10, each MS will send a CQI report to the BS on the MS Tx frame 135. That is, MSI will send its CQI on timeslot 0, MS2 will send its CQI on timeslot 1, and so forth. Based on the values of the CQI received by the BS, the BS will send the header(H)/data information on the BS Tx frame 130 to the user selected based an all CQI reports. In FIG. 7, as an example, the MS with the highest CQI could be selected. A fairer scheduler would also consider the past history of allocations, the amount of data that needs to be transmitted to the MS, and the priority of the data that needs to be transmitted to the MS. An example of a scheduler is a "proportional fair" scheduler which considers requested data rate and throughput in scheduling transmissions. Again there is an offset of three timeslots between the two frames because the MS may not be able to receive and transmit at the same time. One timeslot may be used to transmit the header information. Each user will read the header information and will know which user the data is intended for. Note that this header may contain information regarding different modulations applying various data rates. Other methods of scheduling may also be used. (0044] In conventional systems, the BSC decided which timeslots were to be used for data transmission and which ones for fast scheduling (header information), at what frequency the information was to be sent, and which users were entitled to use the resources. In the present invention, these tasks are no longer performed by the BSC, but are now assigned to the BS. This allows for even faster scheduling and thus increasing the overall system capacity, since higher order modulations (e.g. 8PSK) requiring good channel condition can be used more often. [00451 Referring to FIG. 10, as the number of timeslots increase in a frame, the CQI becomes more reliable and accurate. As mentioned above, the average measurement WO 2005/117464 PCT/US2005/015049 and estimation becomes more accurate when the terminal has been reading all the transmit timeslots. Therefore, MS3 and MS4 will provide the most reliable CQI estimate because timeslots 141 and 142 of the UL 135 can measure all BS Tx 130 slots. In order for each user to benefit from receipt of maximum data due to the position of the timeslot in the frame, an algorithm which rotates the MS users is designed. FIG. 11 is a flowchart that incorporates such an algorithm. In block 145, the receiving unit in the MS will determine whether the data is intended for the MS. If it is, the MS will (block 150) position itself on the last timeslot available in order to prepare for proper transmission of the data. If the data is not intended for the MS, the algorithm in block 155 performs a clockwise or counter-clockwise rotation of users enabling the correct MS to receive the data on the last timeslot available. The order of the reports from the mobile stations that are not receiving the downlink is changed. This rotation ensures fairness, since the timeslot where the uplink report takes place determines also the accuracy of the report itself. These steps will be repeated for the next frame as indicated by Mock 160. This algorithm also makes sure that two users are not transmitting on the same timeslot. [0046] By way of another example, as observed in FIG. 12, timeslot 175 of the Rx frame 170 can measure only timeslots 195 and 200 of the Tx frame 165. Timeslot ISO of the Rx frame 170 can measure timeslots 195, 200, and 205 of the Tx frame 165. Finally, timeslots 185 and 190 of the BS Rx frame 170 can measure all timeslots 195, 200, 205, and 210 of the Tx frame 165. In this example, timeslot 190 is always receiving data. Timeslot 190 stays in the same position because it is still receiving data. After rotation as shown in the second part of the Rx frame 170, using the above-mentioned algorithm, timeslot 180 is now located at the third position on Rx frame 170. Because of its new position, timeslot 180 can now measure all timeslots 215, 220, 225, and 230 of the Tx frame 165. This system ensures fairness in receipt of data. The algorithm will provide rotation of users such that each one will benefit from receipt of maximum data. One embodiment incorporates a "proportional fair" scheduler mechanism into the rotation algorithm. In this way, the rotation considers both channel quality and throughput. [0047] Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips WO 2005/117464 PCT/US2005/015049 that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. [0048] Those of skill in the art would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. (0049] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. [0050] The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information lWO 2005/117464 PCT/US2005/015049 to, the storage medium. In the alternative, the storage medium may be integral to the processor The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. [0051] Headings are included herein for reference and to aid in locating certain sections. These headings are not intended to limit the scope of the concepts described therein under, and these concepts may have applicability in other sections throughout the entire specification. [0052] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. [0053] WHAT IS CLAIMED IS: WO 2005/117464 PCT/US2005/015049 CLAIMS 1: In a communications system supporting a Global System for Mobile communications (GSM) protocol, a method of transmitting a signal over a wireless link, the method comprising: receiving information indicative of a quality, measure of the link for a first entity; determining a time frame for transmission based on the information; and transmitting the signal during the time frame. 2. The method of claim 1, wherein transmitting the signal further comprises transmitting a stream of information bits based on the information. 3. The method of claim 1, wherein the receiving information comprises receiving a channel quality indicator. 4. The method of claim 3, wherein the wireless link is a down link for transmission from a first entity to a second entity and wherein the channel quality indicator is a measure of the downlink and is sent on the uplink from the second entity to the first entity. 5. The method of claim 1, further comprising assigning a channel based on the information. 6. The method of claim 1, wherein the system supports a General Packet Radio Service (GPRS) protocol. 7. The method of claim 1, wherein the system supports an Enhanced Data rates for a Global Evolution (EDGE) protocol. 8. In a communications system supporting a Global System for Mobile communications (GSM) protocol, an infrastructure apparatus configured to transmit a signal over a wireless link, the infrastructure apparatus comprising: means for receiving information indicative of a quality measure of the link; WO 2005/117464 PCT/US2005/015049 means for determining a time frame for transmission based on the information; and means for transmitting the signal during the time frame. 9. The infrastructure apparatus of claim 8, wherein the signal further comprises a stream of information bits based on the information. 10. The infrastructure apparatus of claim 8, wherein the information comprises a channel quality indicator. 11. The infrastructure apparatus of claim 10, wherein the wireless link is a down link for transmission from a first entity to a second entity and wherein the channel quality indicator is a measure of the downlink and is sent on the up link from the second entity to the first entity. 12. In a communications system supporting a Global System for Mobile communications (GSM) protocol, an infrastructure apparatus configured to transmit a signal to a mobile station over a wireless link, the infrastructure apparatus comprising: a receiver configured to receive information indicative of a quality measure of the wireless link; and a transmitter coupled to the receiver and configured to transmit the signal including assignment of a channel based on the information during a timeslot wherein the timeslot is selected based on the information. 13. The infrastructure apparatus of claim 12, wherein the signal further comprises a stream of information bits based on the information. 14. The infrastructure apparatus of claim 13, wherein the information is a channel quality indicator. 15. The infrastructure apparatus of claim 14, wherein the wireless link is a down link for transmission from a first entity to a second entity and wherein the channel WO 2005/117464 PCT/US2005/015049 quality indicator is a measure of the downlink and is sent on the up link from the second entity to the first entity. 16. In a communications system supporting a Global System for Mobile communications (GSM) protocol, a method of transmitting a signal over a wireless link during a timeslot within a time frame, the method comprising: transmitting, from a first entity, information indicative of a quality measure of the wireless link; and receiving after a delay, at the first entity, the signal including assignment of a channel based on the information during said timeslot. 17. The method of claim 16, wherein receiving the signal ftuther comprises receiving a stream of information bits based on the information. 18. The method of claim 16, further comprising measuring a carrier-to-interference ratio for the wireless channel, wherein the information indicative of a quality measure is based on the measured carrier-to-interference ratio. 19. The method of claim 18, wherein the transmitting comprises transmitting information indicative of a carrier-to-interference ratio for the wireless link. 20. In a communications system supporting a Global System for Mobile communications (GSM) protocol, a mobile station for receiving a signal through a wireless link from an infrastructure apparatus, the mobile station comprising: means for transmitting to the infrastructure apparatus information indicative of a quality measure of the wireless link during a timeslot within a time frame; and means for receiving after a delay, from the infrastructure apparatus the signal including assignment of a channel based on the information during said timeslot. 21. The infrastructure apparatus of claim 20, wherein the signal further comprises a stream of information bits based on the information. WO 2005/117464 PCT/US2005/015049 a quality measurement unit for iteratively measuring link quality of a communication link; and a quality message processing unit for generating said stream of information bits based on said measured link quality. 28. The apparatus according to claim 27, wherein said means for scheduling further comprises a unit for compensation of said link quality with an offset. 29. The apparatus according to claim 28, wherein said offset is a function of transmit power. 30. In a communications system supporting a Global System for Mobile communications (GSM) protocol, an apparatus comprising: means for receiving quality indicators for a plurality of communication links; means for determining said quality indicators; and means for generating and sending a first stream of information bits on at least one time slot and a second stream of information bits on at least one time slot. 31. In a communications system supporting a Global System for Mobile communications (GSM) protocol, a mobile station comprising: a memory storage unit; and a processor coupled to the memory storage unit and adapted for: determining a slot position for transmission on an uplink; and applying an algorithm for rotating the slot position. 32. In a communications system supporting a Global System for Mobile communications (GSM) protocol and a down link communication having a first plurality of time slots and an up link communication having a second plurality of time slots, a method comprising: determining at a mobile station whether data is directed to said mobile station; if said data is directed to said mobile station, positioning the mobile station on a last position of said second plurality of time slots; and WO 2005/117464 PCT/US2005/015049 if said data is not directed to said mobile station, performing an algorithm for rotation wherein a selected mobile station is positioned on said last position of said second plurality of time slots. 33. The method according to claim 32, wherein said algorithm is a proportional fair scheduler. 34. The method according to claim 32, wherein the algorithm rotates a mobile station capable or receiving the best average of said data and not currently receiving said data. 35. The method according to claim 34, wherein said step of rotating is clockwise. 36. The method according to claim 34, wherein said step of rotating is counterclockwise. Dated this 24th day of November, 2006 S. AFSAR of K & S PARTNERS AGENT FOR THE APPLICANTS 22 ABSTRACT "Channel Estimation and Channel Quality Indicator (CQI) Measurements for a High Speed Downlink GPRS" An apparatus for providing a Time Division Multiplexing (TDM) scheme for link adaptation including use of channel estimation and Channel Quality Indicator (CQI) measurements by bundling several timeslots of a frame within the existing GSM/GPRS/EDGE system. An algorithm for providing rotation of MS users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission of information.

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
“Channel Estimation and Channel Quality Indicator (CQI) Measurements for a High Speed Downlink GPRS"
QUALCOMM INCORPORATED,
an American company of 5775 Morehouse Drive ,
San Diego, California 92121-1714, United States of America
The following specification particularly describes the invention and the manner in which it is to be performed.

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CHANNEL ESTIMATION AND CHANNEL QUALITY INDICATOR (CQI) MEASUREMENTS FOR A HIGH-SPEED DOWNLINK GPRS
BACKGROUND
Field
|00011 The present invention relates to wireless communication systems generally and
specifically to scheduling data transmissions in a Global System for Mobile communications referred to as GSM.
Background
[0002J The Global System for Mobile communications (GSM) wireless
telecommunications standard defines a set of widely available digital communications protocols for use within a digital wireless telephone system. The GSM specifications are developed by an international effort and adopted by the European Telecommunications Standard Institute (ETSI, 06921 Sophia Antipolis Cedex, France). The General Packet Radio Service (GPRS) is a set of new GSM bearer services that provides high-speed packet-mode transmission within the Public Land Mobile Network (PLMN) and towards external networks. And, the Enhanced Data rates for a Global Evolution (EDGE) were introduced to improve circuit switch and packet switch GSM data services. At the time of inception of the GSM/GPRS/EDGE standard, which supports voice and high rate packet data services, the use of Time Division Multiple Access (TDMA) within the GSM/GPRS/EDGE Over-The-Air (OTA) protocol increased the efficiency with which the given radio frequency bandwidth could be used to conduct wireless telephone calls. Even increasing services and demand require efficient ways of providing system resources to more and more data users. There is a need, therefore, to provide high speed data transmissions in a GSM/GPRS/EDGE environment.
SUMMARY
[0003] The embodiments disclosed herein address the above stated needs by providing
an apparatus that provides a Time Division Multiplexing (TDM) scheduling scheme including use of channel estimation and Channel Quality Indicator (CQI) measurements

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3
by bundling several timeslots of a frame within the existing GSM/GPRS/EDGE
framework.
[0004] One embodiment provides an apparatus, in a wireless communication system
supporting voice and high packet data services, which performs channel estimation, determines a Channel Quality Indicator (CQI) index, and returns assignment/data information based on the CQI index. According to this embodiment, an algorithm enables rotation of Mobile Station (MS) users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission of information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The invention is illustrated by way of example and not limitation and the figures
of the accompanying drawings in which like references denote like or corresponding parts, and in which:
[0006) FIG. 1 is a block diagram of a cellular telephone system configured in
accordance with the GSM/GPRS/EDGE standards.
(0007) FIG. 2 is a diagram illustrating the case of voice services being sent on timeslot
1 of the transmitting unit (Tx) frame and being received on timeslot 1 of the receiving
unit (Rx) frame viewed from the base station.
[0008] FIG. 3 is a diagram illustrating the case of high speed circuit switch data being
sent on timeslots 1 and 2 of the transmitting unit (Tx) frame and being received on timeslot 1 of the receiving unit (Rx) frame viewed from the base station.
[0009] FIG. 4 is a diagram illustrating the case of high speed circuit switch data being
sent on timeslots 1,2,3, and 4 of the transmitting unit (Tx) frame and being received on timeslots 3 and 4 of the receiving unit (Rx) frame viewed from the base station.
[0010] FIG. 5 is a diagram illustrating the case of high speed packet data being sent on
timeslots 1 and 3 of the transmitting unit (Tx) frame and being received on timeslot 2 of the receiving unit (Rx) frame.
[0011] FIG. 6 is a diagram of the received power in a MS with respect to time.
[0012] FIG. 7 is a diagram of the CQI for two mobile stations, with respect to time.
[0013] FIC 8 is a block diagram illustrating the assignment and data sent to the MS
based on the CQI received by the BS.

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[001 4] FIG. 9 is a diagram illustrating for each frame, the assignment and data sent to
the particular MS based on the CQI received by the BS.
[0015] FIG. 10 is a diagram demonstrating the assignment and data information being
sent on parts of a frame.
[0016] FIG. 11 is a flowchart illustrating an algorithm for rotating the position of users
on a frame such that each user will benefit from measuring all timeslots of the frame
resulting in better channel quality.
[0017] FIG. 12 is a diagram illustrating the position of the MS users after performing
the algorithm of rotation of FIG. 11.
[0018 ] FIG. 13 is a diagram showing the bundling of several timeslots into one channel.
[0019] FIG. 14 is a diagram demonstrating timeslots containing midambles used for
channel estimation and CQI reporting.
DETAILED DESCRIPTION
|002O) The word "exemplary" is used exclusively herein to mean "serving as an
example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the present invention are presented in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
[0021J The present invention relates to bundling several timeslots of a frame together in
order to estimate a channel's quality and to send assignment and data information to the mobile station (MS) with a good channel quality within the existing GSM/GPRS/EDGE system. One embodiment also provides an algorithm which enables rotation of MS users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission. In a high rate packet data system, upon receipt of the paging messages from one or more base stations, the MS measures the Signal-to-Noise-and-Interference Ratio (SNIR) of the forward link signals and sends a Channel Quality Indicator (CQI) to the Base Station (BS) at each frame or bundle of timeslots. This BS, in turn, sends assignment/data information to the MS which has good channel quality.
[0022] The following discussion develops the preferred embodiment by first presenting
a system supporting a GSM/GPRS/EDGE system. Next, a TDM scheduling scheme for link adaptation is introduced. Then the TDM scheduling scheme, which includes use of

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channel estimation experienced by each mobile station and which may be used by the
scheduler to optimally allocate the radio resources is explained. Finally, it is helpful to
discuss how this TDM scheduling scheme may be implemented into the
GSM/GPRS/EDGE system and provide the above-mentioned benefits.
[0023] Note the embodiments are provided as exemplars throughout this discussion;
however, alternate embodiments may incorporate various aspects without departing from the scope of the present invention. Specifically, the present invention is applicable to a data processing system, a wireless communication system, a unidirectional broadcast system, and any other system desiring efficient transmission of information.
Global System for Mobile communications (GSM)
|0024] The Global System for Mobile communications (GSM) wireless
telecommunications standard is set of widely available digital communications protocols for use within a digital wireless telephone system. The GSM specifications were developed by an international effort and have been adopted by the European Telecommunications Standard Institute (ETSI, 06921 Sophia Antipolis Cedex, France). The General Packet Radio Service (GPRS) is a set of new GSM bearer services that provides high-speed packet-mode transmission within the PLMN and towards external networks. And, the Enhanced Data rates for a Global Evolution (EDGE) was introduced to improve circuit switch and packet switch GSM data services. A wireless telephone system configured in a manner consistent with the use of the GSM/GPRS/EDGE standards is shown in FIG. 1. GSM Mobile-services Switching Center (MSC) 16 switches or connects telephone calls between the wireless system access network, namely the Base Station Subsystems (BSS) 15, and wireline based Public Switched Telephone Network (PSTN) 18, which may also be a Public Land Mobile Network (PLMN). GSM MSC 16 provides telephone switching, billing, subscriber unit tracking, subscriber unit authorization, and some handoff control functionality.
[0025] BSS 15 is comprised of base station controller (BSC) 14 and any base
transceiver station(s) (BTS) 12 coupled thereto. As defined in the GSM specifications, the interface between GSM MSC 16 and BSS 15 is referred to as the GSM "A or Iu-CS
interface," which separates the GSM/GPRS/EDGE network switching equipment from the Time Division Multiple Access (TDMA) based radio equipment. BSC 14 is

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6
involved with handoff processing and signal processing resource allocation within BTSs
12 so that multiple subscriber units 10, also referred to as Mobile Stations (MSs), can
conduct telephone calls simultaneously. BTS 12 interfaces the subscriber units 10 via
radio frequency (RF) signals and a well defined OTA protocol to the
GSM/GPRS/EDGE wireless network. BTS 12 comprises radio transmission and
reception devices, up to and including antenna devices, and also all the signal
processing specific to the radio interface. BTSs can be considered as complex radio
modems. Subscriber unit MS 10 provides radio and processing functions to access the
GSM/GPRS/EDGE network through the radio interface to either the user of subscriber
unit 10 or some other terminal equipment, such as a facsimile machine or personal
computer. A particular subscriber unit MS 10 may switch the BTS 12 with which it
interfaces as its location changes, but can only communicate with one BTS 12 at a given
instant. Within this application, the capability to switch from one BTS 12 to another
BTS 12, where only one radio interface exists at any instance, is referred to as
subscriber unit hard handoff.
[0026] To make a wireless telephone call, a network connection must be established
between subscriber unit 10, often referred to as a "mobile unit," and PSTN 18. PSTN 18 is the CONVENTIONAL wireline telephone system. To conduct the telephone call in a mobile fashion, a portion of the network connection is formed via the exchange of Radio Frequency (RF) signals between subscriber unit 10 and BTS 12. The remaining portion of the network connection is typically formed through wire-based connections
that pass through BSS 15 and through GSM MSC 16. In accordance with the GSM/GPRS/EDGE OTA protocol, which is one of the protocols that make up the
GSM/GPRS/EDGE wireless telecommunications standard, TDMA technology is used to establish a set of channels within the above identified RF signals used to interface a subscriber unit 10 with a BTS 12. These channels are used to separate and distinguish the various sets of data associated with the various telephone calls being made at any given time. The various sets of data include user data which normally takes the form of digitized audio information, and signaling data which is comprised of the signaling
messages used to orchestrate the processing of a telephone call.
[0027] At the time of the inception of the GSM/GPRS/EDGE standard, the use of
TDMA within the GSM/GPRS/EDGE OTA protocol increased the efficiency with which the given radio frequency bandwidth could be used to conduct wireless telephone

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calls with respect to older analog cellular systems. Increasing the efficiency with which
the available radio frequency bandwidth i5 used is desirable because only a limited
amount of RF bandwidth exists, and the amount of bandwidth is usually the limiting factor as to the number of calls that can be conducted by a particular wireless cellular telephone system. Since the inception of the GSM/GPRS/EDGE wireless telecommunications protocol, however, other wireless technologies have been perfected that allow a greater number of telephone calls to be conducted in a given RF bandwidth. Since efficient use of radio frequency bandwidth is highly desirable, the use of these more efficient technologies is now preferred. The GSM/GPRS/EDGE system supports transmission and reception of voice, high speed circuit switch data and high speed packet data.
[0028] FIG. 2 is a diagram illustrating voice data sent on timeslot 1 of the transmitting
unit (Tx) frame 20. Note that transmission and reception of information are viewed from the Base Station (BS). Since voice data has to be transmitted and received on the same timeslot, this data will be received on timeslot 1 of the receiving unit (Rx) frame 25. One frame 20 is made up of eight timeslots. Note timeslot 30 is identified for clarity. An architectural offset of three timeslots between the Tx and the Rx is required because the data cannot be transmitted and received at the same time. That is, the data is received on frame 25 with an offset of three timeslots. The information is received in the same order sent. This offset includes at least one timeslot 30 to allow for transition between transmission and reception of the data. The BS notifies the MS of the assignment of the timeslot receiving data. The upper layer signaling in the BS enables reservation of the timeslot.
[0029] FIG. 3 is a diagram illustrating high speed circuit switch data sent on timeslots 1
and 2 of the transmitting unit (Tx) frame 35. The high speed circuit switch data, which uses timeslots, will be received on timeslot 1 of receiving unit (Rx) frame 40. Again, eight timeslots form a frame 35 and an offset of three timeslots between the Tx frame 35 and the Rx frame 40 is used because the data cannot be transmitted and received at the same time. Usually only one timeslot, i.e. timeslot 45, is used for transition between the transmission and reception states. This configuration enables more flexibility since the
data is spread over two timeslots for transmission of data and spread over one timeslot for reception. Note that this configuration is unnecessary when voice is sent because the number of additional timeslots does not affect the quality of transmission or

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systems employing such an offset. Timeslot 75 is used to switch from transmission to reception. As observed in FIG. 5, timeslots on the BS Tx frame 65 that are used for transmission need not be consecutive since dynamic sharing is allowed between users. The upper layer signaling in the BS makes an assignment where it selects a pool of MS users. Then, with the help of in-band signaling, it makes an allocation where it selects a
single MS user in the pool of users. This assignment is not permanent since it is
performed on a frame by frame basis.
[0032] As mentioned above, FIG. 1 demonstrates the interaction between the various
components of the GSM/GPRS/EDGE system. The MS 10 differs in many ways from
the MS for voice and circuit data services described above. The MS 10 has multi-slot capability which allows increased flexibility and capability. For example, significant differences in the maximum number of slots that can be used for sending/receiving data and in the minimum number of slots separating reception/transmission can be observed. The Serving GPRS Support Node (SGSN) 95 is the node that is serving the MS 10. The SGSN 95 establishes a mobility management context containing information pertaining to mobility and security for the MS 10. The SGSN 95 also collects charging information. The Gateway GPRS Support Node (GGSN) 90 is the node that is accessed by an external packet data network, via the Gb-interface. Routing information stored in the GGSN 90 is used to tunnel user data to the MS 10's current point of attachment, i.e. the SGSN 95. The GGSN 90 also collects charging information. In a conventional GSM/GPRS/EDGE system, a scheduler that determines the timeslot to be used by each
terminal is located in base station controller (BSC) 14. As will be described below, in
the present invention, the scheduler is located in the base station (BTS) 12 to provide for
fast scheduling.
(0033J In FIG. 6, the power received at the MS 10 is plotted against time. A fade
margin, which represents fading of the channel, can be calculated between the highest point of power 105 and the lowest point of power 110. Since this fade margin becomes much smaller in a TDM scheduling scheme described below, it is beneficial to use this known technique within the existing GSM system in order to improve system performance and signal quality.

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TDM Scheduling Scheme For Link Adaptation
[0034] In accordance with the embodiment of the data communication system of the
present invention, downlink data transmission occurs from one BTS 115 to one MS 125
(see FIG. 8) at or near the maximum data rate which can be supported by the downlink
and the system, including the possible use of higher order modulation (8PSK) that
allows higher data rates in EDGE. Uplink data communication can occur from one MS
120 to one or more BTS 115. Data is partitioned into data packets being transmitted
over one or more timeslots. At each frame or multislot, the BTS 115 can direct data
transmission to any MS 120,125 which is in communication with the BTS 115.
(0035] Initially, each MS 120, 125 establishes communication with a BTS 115 using a
predetermined access procedure. In this connected state, the MS 120,125 can receive
data and control messages 127 from the BTS 115, and is able to transmit data and
control messages 127 to the BTS 115. The MS 120,125 then monitors the down link
for transmissions from the base stations in the active set of the MS 120, 125.
Specifically, the MS 120, 125 measures the signal-to-noise-and-interference ratio
(SNIR) of the down link pilot from the serving base stations, as received at the MS 120,
125. Depending on the received SNIR, the MS 120, 125 will send a Channel Quality
Indicator (CQI) back to the BTS 115. As shown in FIG. 7, each MS 120,125 will send a
CQI to the BTS 115 at each time frame.
[0036] As illustrated in FIG. 9, at each frame, MSI and MS2 will each send a CQI to
the BS. Based on these two parameters, the BS will in turn choose a MS based on an internal algorithm that takes into account, among other factors, the CQI reports from all mobile stations and it will transmit a assignment information, such as within a header, to the selected MS. The BS will also send data to this MS at a slightly later time, as shown in FIG. 8.
Implementation of TDM Scheduling Scheme For Link Adaptation In a
GSM/GPRS/EDGE system
[0037] HSD-PRS (High Speed Downlink GPRS) allows the bundling of several
timeslots in order to create a Data Optimized/ Data Voice (DO/DV) like shared channel. As such, HSD-PRS introduces concepts such as fast feedback, fast CQI reporting, and so forth, within the existing GSM/GPRS/EDGE framework. Channel estimation and

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CQI measurements are an important process in HSD-PRS since the optimal allocation of the downlink resources is based on them.
|0038) As demonstrated in FIG. 13, HSD-PRS bundles together several timeslots into
one channel, which is then directed towards a single user. All terminals will be able to receive those timeslots and read the header. The header indicates which, among the terminals sharing the HSD-PRS channel, is the intended recipient. The receiving terminal must read the data part, whereas all the other terminals can read none, a portion, or all of the data part.
100391 For the purpose of reporting, the important part of a timeslot is the midamble, as
shown in FIG. 14. Every timeslot contains a midamble or center point. The MS uses the midamble for channel estimation and CQI measurements. Consequently, every terminal will read a certain number of timeslots within a TDMA frame of the HSD-PRS channel. It will then average the measurement and estimation performed over each of the timeslots. This average will be more accurate if the terminal has been reading all the downlink timeslots. The accuracy of such reporting can therefore be included in the report itself, so that the network can weigh the reports accordingly. The reports, together with the weights, will be used by the network to perform fast scheduling of the terminals.
|0040] If the transmit power changes dramatically from slot to slot, the CQI reporting
may be affected and the base station would have to adjust its scheduling accordingly. In
such a case, the mobile station should report which slots were considered in the estimate
of the CQI, so that the base station can compensate for the CQI value with an offset,
which may be a function of the transmit power in each of the slots that were used by the
mobile station for the CQI estimate.
[0041] Reporting is a fundamental part of HSD-PRS. The network will perform a fast
scheduling of the downlink resource based on such reporting. Fast scheduling takes
place on a TDMA frame basis. It includes both the decision of which user is the
recipient of the information sent on that TDMA frame, as well as the coding and
modulation parameters. Since the HSD-PRS spans over multiple timeslots within a
TDMA frame, the corresponding uplink timeslots can be used for reporting. Reporting
is based on channel estimation. This is in turn performed by the terminals on the
midambles transmitted on the downlink.

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12
(0042) As described in the previous section, a design choice has been done to prevent
the terminals from having to transmit and receive at the same time. Due to the GSM
offset of three timeslots between transmitting and receiving, it is possible to achieve
this. However, some of the terminals will have to interrupt the channel estimation early
in order to start transmitting on the uplink. One timeslot of separation is needed
between the reception and transmission if the mobile station does not support
simultaneous reception and transmission, which is the most common case.
[0043] By implementing the allocation of CQI and fast scheduling offered by the TDM
scheduling scheme into GSM, it is possible to obtain a more advanced system with
increased capacity. As shown in FIG. 10, each MS will send a CQI report to the BS on
the MS Tx frame 135. That is, MSI will send its CQI on timeslot 0, MS2 will send its
CQI on timeslot 1, and so forth. Based on the values of the CQI received by the BS, the
BS will send the header(H)/data information on the BS Tx frame 130 to the user
selected based an all CQI reports. In FIG. 7, as an example, the MS with the highest
CQI could be selected. A fairer scheduler would also consider the past history of
allocations, the amount of data that needs to be transmitted to the MS, and the priority
of the data that needs to be transmitted to the MS. An example of a scheduler is a
"proportional fair" scheduler which considers requested data rate and throughput in
scheduling transmissions. Again there is an offset of three timeslots between the two
frames because the MS may not be able to receive and transmit at the same time. One
timeslot may be used to transmit the header information. Each user will read the header
information and will know which user the data is intended for. Note that this header
may contain information regarding different modulations applying various data rates.
Other methods of scheduling may also be used.
(0044] In conventional systems, the BSC decided which timeslots were to be used for
data transmission and which ones for fast scheduling (header information), at what
frequency the information was to be sent, and which users were entitled to use the
resources. In the present invention, these tasks are no longer performed by the BSC, but
are now assigned to the BS. This allows for even faster scheduling and thus increasing
the overall system capacity, since higher order modulations (e.g. 8PSK) requiring good
channel condition can be used more often.
[00451 Referring to FIG. 10, as the number of timeslots increase in a frame, the CQI
becomes more reliable and accurate. As mentioned above, the average measurement

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and estimation becomes more accurate when the terminal has been reading all the
transmit timeslots. Therefore, MS3 and MS4 will provide the most reliable CQI
estimate because timeslots 141 and 142 of the UL 135 can measure all BS Tx 130 slots.
In order for each user to benefit from receipt of maximum data due to the position of the
timeslot in the frame, an algorithm which rotates the MS users is designed. FIG. 11 is a
flowchart that incorporates such an algorithm. In block 145, the receiving unit in the
MS will determine whether the data is intended for the MS. If it is, the MS will (block
150) position itself on the last timeslot available in order to prepare for proper
transmission of the data. If the data is not intended for the MS, the algorithm in block
155 performs a clockwise or counter-clockwise rotation of users enabling the correct
MS to receive the data on the last timeslot available. The order of the reports from the
mobile stations that are not receiving the downlink is changed. This rotation ensures
fairness, since the timeslot where the uplink report takes place determines also the
accuracy of the report itself. These steps will be repeated for the next frame as indicated
by Mock 160. This algorithm also makes sure that two users are not transmitting on the
same timeslot.
[0046] By way of another example, as observed in FIG. 12, timeslot 175 of the Rx
frame 170 can measure only timeslots 195 and 200 of the Tx frame 165. Timeslot ISO of the Rx frame 170 can measure timeslots 195, 200, and 205 of the Tx frame 165. Finally, timeslots 185 and 190 of the BS Rx frame 170 can measure all timeslots 195, 200, 205, and 210 of the Tx frame 165. In this example, timeslot 190 is always receiving data. Timeslot 190 stays in the same position because it is still receiving data. After rotation as shown in the second part of the Rx frame 170, using the above-mentioned algorithm, timeslot 180 is now located at the third position on Rx frame 170. Because of its new position, timeslot 180 can now measure all timeslots 215, 220, 225, and 230 of the Tx frame 165. This system ensures fairness in receipt of data. The
algorithm will provide rotation of users such that each one will benefit from receipt of
maximum data. One embodiment incorporates a "proportional fair" scheduler
mechanism into the rotation algorithm. In this way, the rotation considers both channel
quality and throughput.
[0047] Those of skill in the art would understand that information and signals may be
represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips

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that may be referenced throughout the above description may be represented by
voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or
particles, or any combination thereof.
[0048] Those of skill in the art would further appreciate that the various illustrative
logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
(0049] The various illustrative logical blocks, modules, and circuits described in
connection with the embodiments disclosed herein may be implemented or performed
with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
[0050] The steps of a method or algorithm described in connection with the
embodiments disclosed herein may be embodied directly in hardware, in a software
module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to
the processor such that the processor can read information from, and write information

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to, the storage medium. In the alternative, the storage medium may be integral to the processor The processor and the storage medium may reside in an ASIC. The ASIC
may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.
[0051] Headings are included herein for reference and to aid in locating certain
sections. These headings are not intended to limit the scope of the concepts described therein under, and these concepts may have applicability in other sections throughout the entire specification.
[0052] The previous description of the disclosed embodiments is provided to enable any
person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0053] WHAT IS CLAIMED IS:

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CLAIMS
1: In a communications system supporting a Global System for Mobile
communications (GSM) protocol, a method of transmitting a signal over a wireless link, the method comprising:
receiving information indicative of a quality, measure of the link for a first entity;
determining a time frame for transmission based on the information; and
transmitting the signal during the time frame.
2. The method of claim 1, wherein transmitting the signal further comprises transmitting a stream of information bits based on the information.
3. The method of claim 1, wherein the receiving information comprises receiving a channel quality indicator.
4. The method of claim 3, wherein the wireless link is a down link for transmission from a first entity to a second entity and wherein the channel quality indicator is a measure of the downlink and is sent on the uplink from the second entity to the first entity.
5. The method of claim 1, further comprising assigning a channel based on the information.
6. The method of claim 1, wherein the system supports a General Packet Radio Service (GPRS) protocol.

7. The method of claim 1, wherein the system supports an Enhanced Data rates for a Global Evolution (EDGE) protocol.
8. In a communications system supporting a Global System for Mobile communications (GSM) protocol, an infrastructure apparatus configured to transmit a
signal over a wireless link, the infrastructure apparatus comprising:
means for receiving information indicative of a quality measure of the link;

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means for determining a time frame for transmission based on the information;
and means for transmitting the signal during the time frame.
9. The infrastructure apparatus of claim 8, wherein the signal further comprises a
stream of information bits based on the information.
10. The infrastructure apparatus of claim 8, wherein the information comprises a channel quality indicator.
11. The infrastructure apparatus of claim 10, wherein the wireless link is a down link for transmission from a first entity to a second entity and wherein the channel quality indicator is a measure of the downlink and is sent on the up link from the second entity to the first entity.
12. In a communications system supporting a Global System for Mobile communications (GSM) protocol, an infrastructure apparatus configured to transmit a signal to a mobile station over a wireless link, the infrastructure apparatus comprising:
a receiver configured to receive information indicative of a quality measure of the wireless link; and
a transmitter coupled to the receiver and configured to transmit the signal
including assignment of a channel based on the information during a timeslot wherein the timeslot is selected based on the information.
13. The infrastructure apparatus of claim 12, wherein the signal further comprises a stream of information bits based on the information.
14. The infrastructure apparatus of claim 13, wherein the information is a channel quality indicator.
15. The infrastructure apparatus of claim 14, wherein the wireless link is a down link for transmission from a first entity to a second entity and wherein the channel

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quality indicator is a measure of the downlink and is sent on the up link from the second entity to the first entity.
16. In a communications system supporting a Global System for Mobile
communications (GSM) protocol, a method of transmitting a signal over a wireless link
during a timeslot within a time frame, the method comprising:
transmitting, from a first entity, information indicative of a quality measure of
the wireless link; and receiving after a delay, at the first entity, the signal including assignment of a
channel based on the information during said timeslot.
17. The method of claim 16, wherein receiving the signal ftuther comprises receiving a stream of information bits based on the information.
18. The method of claim 16, further comprising measuring a carrier-to-interference ratio for the wireless channel, wherein the information indicative of a quality measure is based on the measured carrier-to-interference ratio.

19. The method of claim 18, wherein the transmitting comprises transmitting information indicative of a carrier-to-interference ratio for the wireless link.
20. In a communications system supporting a Global System for Mobile communications (GSM) protocol, a mobile station for receiving a signal through a wireless link from an infrastructure apparatus, the mobile station comprising:
means for transmitting to the infrastructure apparatus information indicative of a
quality measure of the wireless link during a timeslot within a time
frame; and means for receiving after a delay, from the infrastructure apparatus the signal
including assignment of a channel based on the information during said
timeslot.
21. The infrastructure apparatus of claim 20, wherein the signal further comprises a
stream of information bits based on the information.

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a quality measurement unit for iteratively measuring link quality of a communication link; and
a quality message processing unit for generating said stream of information bits based on said measured link quality.
28. The apparatus according to claim 27, wherein said means for scheduling further comprises a unit for compensation of said link quality with an offset.
29. The apparatus according to claim 28, wherein said offset is a function of transmit power.
30. In a communications system supporting a Global System for Mobile communications (GSM) protocol, an apparatus comprising:
means for receiving quality indicators for a plurality of communication links; means for determining said quality indicators; and
means for generating and sending a first stream of information bits on at least one time slot and a second stream of information bits on at least one time slot.
31. In a communications system supporting a Global System for Mobile
communications (GSM) protocol, a mobile station comprising:
a memory storage unit; and
a processor coupled to the memory storage unit and adapted for:
determining a slot position for transmission on an uplink; and applying an algorithm for rotating the slot position.
32. In a communications system supporting a Global System for Mobile
communications (GSM) protocol and a down link communication having a first
plurality of time slots and an up link communication having a second plurality of time
slots, a method comprising:
determining at a mobile station whether data is directed to said mobile station; if said data is directed to said mobile station, positioning the mobile station on a
last position of said second plurality of time slots; and

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if said data is not directed to said mobile station, performing an algorithm for rotation wherein a selected mobile station is positioned on said last position of said second plurality of time slots.
33. The method according to claim 32, wherein said algorithm is a proportional fair scheduler.
34. The method according to claim 32, wherein the algorithm rotates a mobile station capable or receiving the best average of said data and not currently receiving said data.
35. The method according to claim 34, wherein said step of rotating is clockwise.
36. The method according to claim 34, wherein said step of rotating is counterclockwise.

Dated this 24th day of November, 2006

S. AFSAR
of K & S PARTNERS AGENT FOR THE APPLICANTS

22
ABSTRACT
"Channel Estimation and Channel Quality Indicator (CQI) Measurements for a High Speed Downlink GPRS"
An apparatus for providing a Time Division Multiplexing (TDM) scheme for link adaptation including use of channel estimation and Channel Quality Indicator (CQI) measurements by bundling several timeslots of a frame within the existing GSM/GPRS/EDGE system. An algorithm for providing rotation of MS users such that each one will benefit from measuring all timeslots of the frame resulting in more reliable and accurate transmission of information.

CHANNEL ESTIMATION AND CHANNEL QUALITY INDICATOR (CQI) MEASUREMENTS FOR A HIGH SPEED DOWNLINK GPRS

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