Title of Invention

A MULTICAST SERVICE PROVIDING METHOD IN A WIRELESS SYSTEM

Abstract A method of communicating with a plurality of mobile terminals in a wireless communication system, network performing the method by using a MAC entity (20) therein, and a mobile terminal performing the method by using a MAC entity (40) therein are provided to solve the problems of not being able to distinguish the types of service data when common logical channel data is transmitted through a dedicated shred channel. The method comprises: mapping at least one logical channel to a transport channel; and transmitting the at least one logical channel data to a receiving end through the transport channel; wherein the transport channel is an uni-directional shared channel, and, dedicated logical channel data and common logical channel data are transmitted through the uni-directional shared channel, such that data of the uni-directional shared channel contains a first indicator indicating a logical channel type and a second indicator indicating the multicast service, whereby the dedicated logical channel data and the common logical channel data are capable of being identified at the receiving end.
Full Text A MULTICAST SERVICE PROVIDING METHOD IN A WIRELESS SYSTEM
TFCHNICAL FIELD
The present invention relates to a multicast service providing method in a
wireless system
BACKGROUND ART
The developments in wireless mobile communications have lead users to
favor using mobile phones rather than wired telephones. However, for services
providing a large quantity of data, for example an amount above that generally
provided by voice communications, to mobile phones through a wireless access
network, the performance of mobile communication systems cannot match that
of existing wired communication systems. Accordingly, technical developments
for 1MT-2000, a communication system allowing high capacity data
communications, have been made and standardization of the technology is
being actively pursued among various companies and organizations.
, i
A universal mobile telecommunications system (UMTS) is a third
generation mobile communication system that has evolved from a standard
known as Global System for Mobile communications (GSM). This standard is
a European standard which aims to provide an improved mobile
communication service based on a GSM core network and wideband code
division multiple access (W-CDMA) technology.
In December 1998, the ETSI of Europe, the ARIB/TTC of Japan, the T1 of
the United States, and the TTA of Korea formed a Third Generation Partnership
Project (3GPP). The 3GPP is creating detailed specifications for the UMTS
technology. In order to achieve rapid and efficient technical development of the
UMTS, five technical specification groups (TSG) have been created within the
3GPP for performing the standardization of the UMTS by considering the
independent nature of the network elements and their operations.
Each TSG develops, approves, and manages the standard specification
within a related region. Among these groups, the radio access network (RAN)
group (TSG-RAN) develops the standards for the functions, requirements, and
interface of the UMTS terrestrial radio access network (UTRAN), which is a new
radio access network for supporting W-CDMA access technology in the UMTS.
Figure 1 shows a network structure of a general UMTS.
As shown in Figure 1, the UMTS is roughly divided into a
terminal(UE : user equipment), a UTRAN and a core network.
The UTRAN includes one or more radio network sub-systems (RNS),
Each RNS includes an RNC and one or more Node Bs managed by the
RNCs.
Node Bs are managed by the RNCs, receive information sent by the
physical layer of a terminal (e.g., mobile station, user equipment and/or
subscriber unit) through an uplink, and transmit data to a terminal through a
downlink. Node Bs, thus, operate as access points of the UTRAN for a
terminal.
The RNCs perform functions which include assigning and managing
radio resources, and operate as an access point with respect to the core
network.
A primary function of the UTRAN is constructing and maintaining a
radio access bearer (RAB) for a call connection between the terminal and the
- core network. The core network applies quality of service (QoS) requirements
of end-to-end to the RAB, and accordingly, the UTRAN can satisfy the QoS
requirements of the end-to-end by constructing and maintaining the RAB.
The RAB service is divided into an lu bearer service and a radio
bearer service of a lower concept. The lu bearer service handles reliable user
data transmission between boundary nodes of UTRAN and the core network,
while the radio bearer service handles reliable user data transmission
between the terminal and UTRAN.
The core network includes a mobile switching center (MSC) and a
gateway mobile switching center (GMSC) connected together for supporting a
circuit switched (CS) service. The core network also includes a serving GPRS
support node (SGSN) and a gateway GPRS support node connected together
for supporting a packet switched (PS) service.
The services provided to a specific terminal are roughly divided into the
circuit switched (CS) services and the packet switched (PSJ services. For
example, a general voice conversation service is a circuit switched service, while
a Web browsing service via an Internet connection is classified as a packet
switched (PS) service.
For supporting circuit switched services, the RNCs are connected to the
MSC of the core network and the MSC is connected to the GMSC that manages
the connection with other networks. For supporting jacket switched services, the
RNCs are connected to the SGSN and the GGSN of the core network. The
SGSN supports packet communications with the RNCs and the GGSN manages
the connection with other packet switched networks, such as the Internet.
Various types of interfaces exist between network components to allow
the network components to transmit and receive information with each other. An
interface between the RNC and the core network is defined as an lu interface. In
particular, the lu interface between the RNCs and the core network for packet
switched systems is defined as "lu-PS" and the lu interface between the RNCs
and the core network for circuit switched systems is defined as "lu-CS."
A radio network temporary identifier (RNTI) is used to identify a terminal
while connection between the terminal and the UTRAN is maintained. Four
RNTIs are defined ; S-RNTI, D-RNTI, C-RNTI and U-RNTI. The S-RNTI (Serving
RNC RNTI) is assigned by an SRNC (Serving RNC) when a connection between
a terminal and UTRAN is set. The S-RNTI is information by which the SRNC
may identify a corresponding terminal.
The D-RNTI (Drift RNC RNTI) is assigned by a DRNC (Drift RNC) when a
handover occurs between RNCs according to movement of a terminal. The D-
RNTI is information by which the DRNC may identify a corresponding terminal.
The C-RNTI (Cell RNTI) is information by which a terminal may be
identified in a CRNC (Controlling RNC). When a terminal enters a new cell, it is
assigned a new C-RNTI value by the CRNC.
The U-RNTI (UTRAN RNTI) includes an SRNC identity and an S-RNTI.
Since the SRNC and a terminal in the SRNC may be identified, it may be said
that the U-RNTI provides absolute identification information.
When data is transmitted via a common transport channel, aMAC-c/sh
entity adds the C-RNTI or the U-RNTI to a header of a MAC PDU which is then
transmitted. A UE ID type indicator, which indicates type of the RNTI added in
the header of the MAC PDU, is also added to the header.
Figure 2 illustrates a radio protocol between the terminal and the
UTRAN on the basis of the 3GPP wireless access network standards.
With reference to Figure 2, the radio access interface protocol
includes horizontal layers comprising a physical layer, a data link layer and a
network layer, and vertical planes comprising a user plane for transmitting
data information and a control plane for transmitting control signals.
The user plane is a region to which traffic information of a user such
as voice or an IP packet is transmitted. The control plane is a region to which
control information such as an interface of a network or maintenance and
management of a call is transmitted.
In Figure 2, protocol layers can be divided into a first layer (L1), a
second layer (L2) and a third layer (L3) based on three lower layers of an
open system interconnection (OSI) standard model well known in the art of
communication systems.
The first layer (PHY) provides an information transfer service to the
upper layer by using various radio transfer techniques.
The first layer is connected to the MAC layer through a transport
channel, and data is transferred between the MAC layer and the PHY layer
through the transport channel.
Data is transmitted according to transmission time interval (TTI)
through the transport channel. The physical channel transfers data by
dividing it by the unit of certain time called a frame. In order to synchronize
the transport channel between the UE and UTRAN, a connection frame
number (CFN) is used. The CFN value has the range of 0-255 in case of
transport channels except for a paging channel (PCH). That is, CFN is
repeatedly circulated by the period of 256 frames.
Besides the CFN, a system frame number (SFN) is also used to
synchronize the physical channel. The SFN value has the range of 0-4095
and repeated by the period of 4096 frames.
The second layer (L2) includes a MAC layer, a radio link control (RLC)
layer, a broadcast/multicast control (BMC) layer, and a packet data convergence
protocol (PDCP) layer.
The MAC layer provides a re-allocation service of the MAC
parameter for allocation and re-allocation of radio resources.
The MAC layer is connected to the radio link control (RLC) layer
(which is an upper layer) through a logical channel, and various logical
channels are provided according to the kind of transmitted information. In
general, when information of the control plane is transmitted, a control
channel is used. When information of the user plane is transmitted, a traffic
channel is used.
The MAC is classified into an MAC-b sublayer, an MAC-d sublayer
and an MAC-c/sh sublayer according to types of managed transport channels.
The MAC-b sublayer manages a BCH (Broadcast Channel) handling
broadcast of system information, while the MAC-c/sh sublayer manages
shared transport channel such as FACH (Forward Access Channel), DSCH
(Downlink Shared Channel), or the like, shared with other terminals.
In UTRAN, the MAC-c/sh sublayer is positioned at a control RNC
(CRNC) and manages channels shared by every terminal in a cell, so that
one MAC-c/sh sublayer exists in each cell.
The MAC-d sublayer manages a DCH (Dedicated Channel), a
dedicated transport channel for a specific terminal. Accordingly, the MAC-d
sublayer is positioned at a serving RNC (SRNC) managing a corresponding
terminal, and one MAC-d sublayer exists also at each terminal.
A radio link control (RLC) layer supports a reliable data transmission
and may perform a function of segmentation and concatenation of an RLC
service data unit (SDU) coming from a higher layer. The RLC SDU
transferred from the higher layer is adjusted in its size according to a
throughput capacity at the RLC layer, to which header information is added,
and then transferred in a form of a PDU (Protocol Data Unit) to the MAC layer.
The RLC layer includes an RLC buffer for storing the RLC SDU or the RLC
PDU coming from the higher layer.
A broadcast/multicast control (BMC) layer performs functions of
scheduling a cell broadcast message (CB) transferred from the core network
and broadcasting the CB to UEs positioned in a specific cell(s). At the side of
UTRAN, the CB message transferred from the upper layer is combined with
information, such as a message ID, a serial number or a coding scheme, and
transferred in a form of BMC message to the RLC layer and to the MAC layer
through a CTCH (Common Traffic Channel), a logical channel. In this case,
the logical channel CTCH is mapped to a FACH (Forward Access Channel),
a transport channel, and an S-CCPCH (Secondary Common Control Physical
Channel), a physical channel.
A packet data convergence protocol (PDCP) layer is an upper layer
of the RLC layer, allowing data to be transmitted effectively on a radio
interface with a relatively small bandwidth through a network protocol such as
the IPv4 or the IPv6. For this purpose, the PDCP layer performs a function of
reducing unnecessary control information, which is called a header
compression, and in this respect, RFC2507 and RFC3095 (robjst header
compression: ROHC), a header compression technique defined by an
Internet standardization group called an IETF (Internet Engineering Task
Force), can be used. In these methods, because the only information
requisite for the header part of a data is transmitted, control information is
transmitted, so that an amount of data transmission can be reduced.
The RRC layer positioned in the lowest portion of the third layer (L3)
is defined only in the control plane and controls the logical channels, the
transport channels, and the physical channels in relation to the setup, the
reconfiguration, and the release of the RBs. The RB signifies a service
provided by the second layer for data transmission between the terminal and
UTRAN, and setting up the RB means processes of stipulating the
characteristics of a protocol layer and a channel, which are required for
providing a specific service, and setting the respective detailed parameters
and operation methods.
The RLC layer may belong to the user plane or to the control plane
depending upon the type of layer connected at the upper layer of the RLC layer.
If the RLC layer receives data from the RRC layer, the RLC layer belongs to the
control plane. Otherwise, the RLC layer belongs to the user plane.
As shown in Figure 2, there may be several entities in one RLC layer or
one PDCP layer layer. More than one layer may be present because one
terminal generally has a plurality of RBs and only one RLC entity and only one
PDCP entity are used for one RB.
The MAC-sublayer will now be described.
A primary function of the MAC layer existing between the RLC and
the physical layer is mapping the logical channel and the transport channel.
The reason is because channel processing methods of the upper layer and
the lower layer of the MAC are different. That is, at the upper layer of the
MAC, data is processed separately by using the control channel of the
control plane and the traffic channel of the user plane according to the
content of the data that the channel transmits. Meanwhile, at the lower layer,
data is processed separately by using a common channel and a dedicated
channel depending on whether a channel is shared, so inter-channel
mapping is important.
Figure 3 illustrates mapping relations between the logical channel
and the transport channel at the UE. in case of UTRAN, the directions of
arrows are the opposite.
Another important function of the MAC layer may be logical channel
multiplexing. The MAC maps several logical channels to one transport channel
to obtain a multiplexing gain which heightens the efficiency of the transport
channel. Such multiplexing may provide much higher gain for data transmitted
intermittently and packet data. Therefore, the multiplexing function is used for an
SRB (Signaling Radio Bearer) or a packet service (PS) RAB. Because data is
continuously transmitted in a circuit service (CS) RAB, the multiplexing function
is not used. The SRB is an RB used specifically for exchanging an RRC
message or an NAS message between the terminal and the UTRAN.
Accordingly, the MAC provides a flexibility in channel selection and
an efficiency of a channel resource through the channel mapping and logical
channel multiplexing. In this case, in order to support the channel mapping
and the logical channel multiplexing, additional functions are required. That is,
four functions are additionally performed in the MAC.
1. Priority handling
In order to support various channel mapping structures, the MAC
performs a priority handling function. The priority handling includes two types:
one is priority handling among several UEs, and the other is priority handling
for one UE.
The priority handling among UEs corresponds to a case that data of
several UEs are transmitted at the downlink through a common transport
channel (FACH or DSCH). In this case, the MAC first transmits data of a UE
with a higher priority. That is, the MAC suitably allocates the common
channel to each UE at each transmission time interval (TTI), to thereby
heighten an efficiency of the channel resource. This is related to a dynamic
scheduling function.
A priority handling on one UE corresponds to a case that several
logical channels belonging to one UE is mapped to one transport channel.
The MAC determines a priority from the logical channel priority. This is
related to a transport format combination selection, and the MAC selects a
transport format combination that can first transmit data of a logical channel
with a higher priority.
2. Transport format combination selection
The MAC transmits transport blocks (TB) to the physical layer
through the transport channel. The transport format (TF) means a regulation
for a size and the number of TBs that one transport channel transmits. In
determining the TF for a specific transport channel, the MAC should even
consider the transport channel multiplexing in the physical layer.
The transport channel multiplexing refers to mapping plural transport
channels to one coded composite transport channel (CCTrCH). Although this
function is performed in the physical layer, the MAC should consider every
transport channel mapped to the same CCTrCH in determining the TR
Actually, the amount of data processed in the physical layer is the amount of
data transmitted through CCTrCH, so the MAC should determine the TF of
each transport channel in consideration of CCTrCH. In this case, a
combination of TF is called a transport format combination (TFC). The TFC is
not determined by the MAC itself but selected from an available TFC set
(TFCS) that the RRC layer informs. That is, the RRC informs the MAC of an
available TFCS for one CCTrCH in an initial setting, and then the MAC
selects a suitable TFC from the TFCS at each TTI.
Selection of a suitable TFC from a given TFCS at each TTI is a
function performed by the MAC, which includes two steps.
First, the MAC constitutes a valid TFC set in the TFCS assigned to
CCTrCH, and selects an appropriate TFC in the valid TFC set. The valid TFC
set is a set of TFCs actually available for a corresponding TTI among
assigned TFCS. The selection of a suitable TFC is take into account a
channel environment changing at every moment. When a TFC is selected to ' *
be used in the corresponding TTI in the valid TFC set, the MAC selects a
TFC on the basis of a priority of the logical channel. That is, the MAC selects
a TFC that can transmit preferentially data of the logical channel with a
higher priority, and such TFC selection is related to the priority processing
function.
As for the RACH or CPCH, the common transport channel of the
uplink, because one transport channel constitutes one CCTrCH, the term of
the TF selection is used for the channels.
3. Identification
The MAC requires an identification function. The reason is because,
first, the common transport channel is shared for use by several UEs, so
each UE needs to be identified, and second, each logical channel needs to
be identified due to the logical channel multiplexing. Accordingly, the MAC
inserts four types of fields into a header of the MAC PDU for identification as
shown in Figure 4. The fields of the MAC header do not necessarily exist,
and their existence is determined depending on a mapping relation of the
logical channel and the transport channel.
The identification of the terminal is required when the dedicated
logical channel such as DCCH or DTCH is mapped to a common transport
channel such as RACH, FACH, CPCH (Control Physical Channel), DSCH or
USCH (Uplink Shared Channel). For identification of each UE, the MAC adds
a radio network temporary identity (RNTI), identification information of a
terminal, to a UE-ID field of the header and transmits it. The RNTI includes
U-RNTI (UTRAN RNTI), C-RNTI (Cell RNTI) and DSCH-RNTI, so the MAC
also adds a UE-ID type field indicating which RNTI is used and transmits it.
Identification of the dedicated logical channels is made through a C/T
field. The reason is because, first, unlike other logical channels, several
dedicated channels can be mapped to one transport channel, and second,
the dedicated logical channel is processed in an MAC-d of a serving radio
network controller (SRNC) and other logical channels are provided in an
MAC-c/sh of a control radio network controller (CRNC). Dedicated logical
channels mapped to one transport channel respectively have a logical
channel identity that is used as a C/T field value. If only one dedicated logical
channel exists in the transport channel, the C/T field is not used.
Figure 5 illustrates MAC header information according to a mapping
relation between the dedicated logical channel and the transport channel in
accordance with the conventional art.
As shown in Figure 5, the C/T field exists only when several
dedicated logical channels (DCCH or DTCH) are mapped, 'N' means non-
existence of a header, and '-' means there is no mapping region. In addition,
because the UE-1D field exists together with the UE-ID type field at the time,
so it is simply indicated by UE-ID.
4. Measurement of traffic volume and transport channel type
switching
In order to support the.RRC in dynamically controlling a radio bearer,
the MAC performs functions of measurement of a traffic volume and change
of a type of a transport channel.
The measurement of traffic volume is performed on the transport channel.
The MAC measures the size of the RLC buffer of every logical channel mapped
to the transport channel at each TTI and adds the sizes to calculate a transport
channel traffic volume. The traffic volume of a transport channel indicates the
amount of data to be transmitted by that transport channel. The MAC reports the
measurement results to the RRC and the measurement results serve as a basis
for the RRC to determine whether a corresponding transport channel may
sufficiently transmit the measured amount of data.
The MAC reports the measurement result to the RRC. Unlike the
measurement of the traffic volume performed at every TTI, the measurement
result report is performed when a specific condition is satisfied unlike. The
report type includes an event trigger method for reporting the measurement
result when the measurement result exceeds a threshold value, and a
periodical method for reporting the measurement result at every
predetermined time.
Upon receiving the measurement result, the RRC determines
whether a current transport channel is suitable for each radio bearer, and if
the current transport channel is not suitable, the RRC commands the MAC to
change a transport channel of a radio bearer. Namely, the transport channel
type change is a function for effectively managing a resource of the transport
channel by selectively using a suitable transport channel according to the
amount of given data.
When a DCH is used, the efficiency of a coded-divided channel may be
problematic and there may not be enough codes for use for data transmissions
having burst characteristics that result in data being crowded at a specific time
during a communication session. In order to solve this problem, several
scrambling codes may be used. However, the complexity of a receiver may
increase without increasing the efficiency of the code-divided channel.
The DSCH is a channel shared by several users transmitting dedicated
control or traffic data. Several users may share one channel by performing code
multiplexing. Therefore, the DSCH may be defined as a series of code sets.
Unlike the uplink, a code shortage occurs in the downlink because the
number of codes one sector may have in one base station is limited due to a
spreading factor. For a high transmission rate, a low spreading factor must be
used, thereby reducing the number of physical channels.
Additionally, such data services generally have burst characteristics.
Therefore, if one channel is continuously allocated to one service, codes cannot
be efficiently used.
In order to solve these problems, a method in which one channel is
shared by a plurality of users may be employed. In order to share one channel,
code multiplexing is used. Code allocation is performed for every radio frame, for
example time multiplexing.
The multimedia broadcast/multicast service (MBMS) will now be
described.
The CBS has the limitations. First, the maximum length of a CBS
message is limited to 1230 octet. Therefore, a CBS message is not suitable for
broadcasting or multicasting multimedia data. Second, since the CBS message
is broadcast to every terminal in a specific cell, multicasting for providing a
service to only a specific terminal group is not possible wirelessly. For these
reasons, a new service called MBMS has been proposed.
The MBMS is a service for transmitting multimedia data such as
audio, video or image data to plural terminals by using a uni-directional point-
to-multipoint bearer service. The MBMS is divided into a broadcast mode and
a multicast mode. That is, the MBMS is divided into an MBMS broadcast
service and an MBMS multicast service.
1. Users receive a service announcement provided by a network. The
service announcement indicates a list of services to be provided and provides
related information to terminals.
2. The network sets a bearer for a corresponding broadcast service.
3. Users receive a service notification provided by the network. The
service notification provides information related to broadcast data to be
transmitted to terminals.
4. Users receive broadcast data from the network.
5. The network releases a bearer for a corresponding broadcast
service.
The MBMS broadcast mode is a service for transmitting multimedia
data to every user in a broadcast area. The broadcast area means a
broadcast service available area. One or more broadcast areas may exist in
one PLMN, one or more broadcast services can be provided in one
broadcast area, and one broadcast service can be provided to several
broadcast areas.
The MBMS multicast mode is a service for transmitting multimedia
data only to a specific user group existing in a multicast area. The multicast
area means a multicast service available area. One or more multicast areas
can exist in one PLMN, one or more multicast services can be provided in
one multicast area, and one multicast service can be provided to several
multicast areas.
In the multicast mode, a user is requested to join a multicast group to
receive a specific multicast service. At this time, the multicast group refers to
a user group that receives the specific multicast service, and joining refers to
a behavior of being admitted to the multicast group intending for receiving the
specific multicast service.
1. A user subscribes to a multicast subscription group. Subscription
involves establishing a relationship between a service provider and a user. A
multicast subscription group is a group of users that have completed the
subscription procedure.
2. Users who have subscribed to the multicast subscription group
receive a service announcement provided by the network. The service '
announcement indicates list of services to be provided and provides related
information to terminals.
3. In order for a user that has subscribed to a multicast subscription
group to receive a specific multicast service, the user must join a multicast
group. A multicast group is a group of users that receive the specific multicast
service joining a multicast group involves joining the multicast group intending to
receive the specific multicast service. Joining a multicast group is also referred to
as MBMS multicast activation. Through MBMS multicast activation, a user may
receive specific multicast data.
4. The network sets a bearer for a corresponding multicast service.
5. A user joining the multicast group receives a service notification
provided by the network. The service notification provides information regarding
multicast data to be transmitted to terminals.
6. Users receive multicast data from the network.
7. The network releases a bearer for a corresponding broadcast
service.
MBMS data is transmitted from the RNC to a base station and to a
terminal by using services of the PDCP layer, the RLC layer, the MAC layer
and the physical layer positioned at the user plane of the UTRAN protocol.
That is, the MBMS data transmitted from the core network (CN) is subjected
to a header compression at the PDCP layer and transmitted as an RLC UM
entity through an RLC UM SAP, and then, the RLC UM entity is transmitted to
the MAC layer through the common iraffic channel, the logical channel.
The MAC layer adds an MAC header to the received MBMS data and
transfers it to the physical layer of the base station through the common
transport channel. And then, the MBMS data undergoes coding and
modulation in the physical layer and transmitted to the terminal through the
common physical channel.
An MBMS RB, a radio bearer (RB) for the MBMS, serves to transmit
user data of one specific MBMS service transferred from the core network to
UTRAN to a specific terminal group. The MBMS RB is roughly divided into a
point-to-multipoint RB and a point-to-point RB. In order to provide the MBMS
service, UTRAN selects one of the two types of MBMS RBs. In order to
select the MBMS RB, UTRAN recognizes the number of users of the specific
MBMS service existing in one cell. UTRAN internally sets a threshold value,
and if the number of users existing in a cell is smaller than the threshold
value, UTRAN sets the point-to-point MBMS RB, whereas if the number of
users existing in a cell is greater than the threshold value, UTRAN sets the
point-to-multipoint MBMS RB.
The wireless system of the third generation partnership project
(3GPP) proposes a downlink shared channel (DSCH) including a high speed
downlink shared channel (HS-DSCH), particularly to support a packet data
service.
In order for the DSCH to provide a multicast service, it should
support the point-to-multipoint radio bearer, and at this time, the common
logical channel such as CTCH or MTCH (MBMS Traffic Channel) should be
mapped to the DSCH. In this respect, however, in the conventional art,
because the DSCH transmits only data of the dedicated logical channel, a
field for identifying a logical channel mapped to the DSCH is not added in the
MAC header. Thus, when the common logical channel data is transmitted
through the DSCH, in the case that the field indicating a type of the logical
channel is not included in the MAC header in transmission of the DSCH, the
terminal can not know which type of logical channel a data unit received
through the DSCH belong to, and thus, there is a high possibility that a
communication error occurs.
The above references are incorporated by reference herein where
appropriate for appropriate teachings of additional or alternative details,
features and/or technical background.
Accordingly, the present invention provides a multicast service providing
method in a wireless system, comprising:
mapping at least one logical channel to a transport channel; and
transmitting the at least one logical channel data to a receiving end through the
transport channel;
wherein the transport channel is an uni-directional shared channel, and, dedicated
logical channel data and common logical channel data are transmitted through the uni-
directional shared channel, such that data of the uni-directional shared channel
contains a first indicator indicating a logical channel type and a second indicator
indicating the multicast service, whereby the dedicated logical channel data and the
common logical channel data are capable of being identified at the receiving end.
The present invention also provides in a wireless communication method
in which a dedicated logical channel data and a common logical channel data re
transmitted by using an uni-directional shared channel, wherein a data
transmitted through the shared channel comprises : a first-indicator indicating a
logical channel type ; a second indicator indicating a multicast service type ; and
a service data unit.
The present invention further provides a method of providing a multicast
service in a radio communication system, the method comprising : receiving data
of a dedicated logical channel having a corresponding first dedicated transport
channel ; receiving data of a common logical channel having a corresponding
second dedicated transport channel ; processing the dedicated logical channel
data and the common logical channel data to form multiplexed data that contains
an identifier to provide distinction between the dedicated logical channel data
and the common logical channel data ; newly establishing a. shared transport'
channel independent from the first and second dedicated transport channels ;
and transporting the multiplexed data via the newly established shared transport
channel.
The present invention still further provides a method of communicating
with a plurality of terminals in a wireless communication system, the method
comprising : mapping at least one common logical channel to a shared physical
channel ; and communicating with the plurality of terminals by transmitting data
using the shared physical channel, the shared physical channel characterized by
at least one of having an associated channel and supporting variable channel
code, wherein the associated channel comprises information for interpreting data
transmitted in the shared physical channel.
The present invention still further provides a method of communicating
with a plurality of mobile terminals in a wireless communication system, the
method comprising : using a logical channel selection module to map at least
one of a first logical channel and a second logical channel to a shared physical
channel, wherein at least one of the first and second logical channels is a
common logical channel ; and communicating with the plurality of mobile
terminals by transmitting data using the shared physical channel, the shared
physical channel characterized by one of having an associated channel and
supporting variable channel code, wherein the associated channel comprises
information for interpreting data transmitted in the shared physical channel.
The present invention still further provides a method of communicating
with a plurality of terminals in a. wireless communication system, the method
comprising : receiving data in a shared physical channel, the shared physical
channel characterized by at least one of having an associated channel and
supporting variable channel code, wherein the associated channel comprises
information for interpreting data received in the shared physical channel ; and
examining a header of the data received in the shared physical channel to
determine whether the data is processed.
The present invention still further provides a network for communicating
with a plurality of terminals in a wireless communication system, the network
comprising : a logical channel selection module adapted to map at least one of a
first logical channel and a second logical channel to a shared physical channel ,
wherein at least one of the first and second logical channels is a common logical
channel ; and a transmitting unit adapted to perform at least one of transmitting
information on a channel associated with the shared physical channel, the
information associated with interpreting data transmitted in the shared physical
channel, and transmitting data in the shared physical channel using variable
channel code.
The present invention still further provides a mobile unit for
communicating with a network in a wireless communication system, comprising :
a receiving unit adapted to receive data in a shared physical channel, the shared
physical channel characterized by at least one of having an associated channel
and supporting variable channel code, wherein the associated channel
comprises information for interpreting data received in the shared physical
channel ; and a demultiplexing unit adapted examine a header of the data
received in the shared physical channel to determine whether the data is
processed.
DISCLOSURE OF THE INVENTION
Therefore, an object of the present invention is to provide a data
transmission method capable of discriminating a type of multicast service
data when the multicast service data is transmitted through a shared channe
Another object of the present invention is to provide a data
transmission method capable of providing a multicast service through a
shared channel.
To achieve at least the above objects in whole or in part, there is
provided a multicast service method in a wireless system in which service
data of a logical channel is mapped to a common transport channel and
transmitted to a terminal, including: adding a logical channel identifier to
service data to be transmitted; and mapping corresponding service data to a
common transport channel.
Preferably, the logical channel is a common logical channel or a
dedicated logical channel, and the common logical channel can be a
common traffic channel (CTCH), a common control channel, an MBMS traffic
channel (MTCH), or an MBMS control channel (MCCH).
Preferably, the common transport channel is a downlink shared
channel (DSCH).
Preferably, the common transport channel is a high speed downlink
shared channel (HS-DSCH).
Preferably, the service data is multimedia broadcast/multicast service
(MBMS) data.
Preferably, the service data is an MBMS protocol data unit, which is
an MAC protocol data unit.
Preferably, the logical channel identifier is a target channel type field
(TCTF), and the TCTF indicates whether a logical channel mapped to the
common transport channel is a common logical channel or a dedicated
logical channel. The logical channel identifier is added when the service data
is transmitted from a medium access control (MAC) layer to a lower layer.
Preferably, the logical channel identifier is added by a common type
of MAC entity such as an MAC-c/sh which manages a common radio
resource of every terminal in a cell.
Preferably, the logical channel identifier is included in a header of the
service data, and the header is an MAC header.
The multicast service method further includes adding a terminal
identifier and an indicator indicating a type of the terminal identifier to the
service data to be transmitted. The terminal identifier is an MBMS radio
network temporary identifier (RNTI), a terminal group identifier, or an MBMS
service identifier.
To achieve at least these advantages in whole or in parts, there is
further provided a multicast service method in a wireless communication
system in which service data of a common logical channel or a dedicated
logical channel is mapped to a downlink shard channel (DSCH) or a high
speed downlink shared channel (HS-DSCH) and transmitted to a terminal,
wherein when a medium access control (MAC) transmits service data
through DSCH or HS-DSCH, it also transmits an indicator indicating a type of
mapping of a logical channel to the service data.
Preferably, the service data is a multimedia broadcast/multicast
service (MBMS) data.
Preferably, the service data is an MBMS protocol data unit, and the
MBMS protocol data unit is an MAC protocol data unit.
Preferably, the indicator is a target channel type field (TCTF).
Preferably, the MAC layer is an MAC-c/sh layer which manages a
common resource of every terminal in a cell.
Preferably, the indicator is included in a header of the service data,
and the header is an MAC header. The MAC header includes a terminal
identifier and an indicator indicating a type of the terminal identifier.
Preferably, the terminal identifier is an MBMS radio network
temporary identifier (RNTI), a terminal group identifier, or an MBMS service
identifier.
To achieve at least these advantages in whole or in parts, there is
further provided .a multicast service method in a wireless communication
system in which service received through downlink shard channel is
transmitted to an upper layer of a terminal, including: reading a logical
channel identifier from service data and recognizing a logical channel through
which corresponding data is to be transmitted; and transmitting received data
to an upper layer of a terminal through the recognized logical channel.
Preferably, the received data is multimedia broadcast/multicast
service (MBMS) data.
Preferably, the logical channel identifier is a target channel type field
(TCTF).
Preferably, if the logical channel for transmitting the service data is a
common logical channel, the received data is transmitted to a resource link
control (RLC) layer through the common logical channel. If the logical
channel for transmitting the service data is a dedicated logical channel, the
received data is transmitted to an MAC-d layer which manages a dedicated
resource through the dedicated logical channel.
Preferably, the recognizing step Is performed in a common type of
medium access control (MAC) layer of a terminal such as an MAC-c/sh layer.
To achieve at least these advantages in whole or in parts, there is
further provided a multicast service method in a wireless communication
system in which data received through downlink shared channel is
transmitted to an upper layer of a terminal, including: reading a logical
channel identifier and a terminal identifier from received data; and
transmitting the received data to an upper layer through a predetermined
logical channel on the basis of the read logical channel identifier and terminal
identifier.
Preferably, the logical channel identifier is a target channel type field
(TCTF).
Preferably, the terminal identifier is an MBMS radio network
temporary identifier (RNTI), a terminal group identifier, or an MBMS service
identifier.
Preferably, the transmitting step includes: checking whether the
logical channel identifier indicates a common logical channel; checking
whether the terminal identifier indicates a terminal group to which a
corresponding terminal belongs; and transmitting received data to an upper
layer according to the check result.
Preferably, if the logical channel identifier indicates a common logical
channel and the terminal identifier indicates a terminal group to which a
terminal belongs, the received data is transmitted to a resource link control
(RLC) layer through the common logical channel. If the logical channel
identifier indicates the common logical channel but the terminal identifier
does not indicate a terminal group to which a terminal belongs, the received
data is discarded.
Preferably, if the logical channel identifier indicates a dedicated
logical channel and the terminal identifier indicates a terminal group to which
a terminal belongs, the received data is transmitted to an MAC-d layer. If the
logical- channel identifier indicates the dedicated logical channel but the
terminal identifier does not indicate a terminal group to which a terminal
belongs, the received data is discarded.
Additional advantages, objects, and features of the invention will be
set forth in part in the description which follows and in part will become
apparent to those having ordinary skill in the art upon examination of the
following or may be learned from practice of the invention. The objects and
advantages of the invention may be realized and attained as particularly
pointed out in the appended claims.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention will be described in detail with reference to the
following drawings in which like reference numerals refer to like elements
wherein:
Figure 1 illustrates a network structure of a general UMTS system;
Figure 2 illustrates a radio access interface protocol between the
terminal and UTRAN on the basis of the 3GPP radio access network
standards;
Figure 3 illustrates an example of a mapping relation between a
logical channel and a transport channel at the UE;
Figure 4 illustrates a structure of MAC PDU for a point-to-point DSCH
in accordance with a conventional art;
Figure 5 illustrates MAC header information according to the
mapping relation of a dedicated logical channel and the transport channel in
accordance with the conventional art;
Figure 6 illustrates a structure of MAC PDU for a point-to-multipoint
DSCH in accordance with the present invention;
Figure 7 illustrates a structure of an common type of an MAC of
CRNC for the point-to-multipoint DSCH and a multicast data processing
method; and
Figure 8 illustrates a structure of an common type of an MAC of a
terminal for the point-to-multipoint DSCH and a multicast data processing
method.
MODES FOR CARRYING OJUfcTHE PREFERRED EMBODIMENTS
The present invention is implemented in a mobile communication
system such as a UMTS (Universal Mobile Telecommunications System)
developed by 3GPP. However, the present invention can be also applied to
communication system operating in a different standard.
The present invention proposes a method in which when UTRAN
transmits radio bearer data through a downlink shared channel (DSCH), the
terminal determines to which logical channel it transfers the data received
through DSCH. In the present invention, DSCH provides a point-to-multipoint
radio bearer service as well as a point-to-point radio bearer service, and
especially, transmits data of a common traffic channel such as CTCH and
MTCH to a specific terminal group.
In order to discriminate the DSCH from that of the conventional art, in
the present invention, if the DSCH is used to provide a point-to-multipoint
radio bearer service, it is called a point-to-multipoint DSCH. On the other
hand, if the DSCH is used to provide a point-to-point radio bearer service, it
is called a point-to-point DSCH. Also, in the present invention, a DSCH
includes a high speed downlink shared channel (HS-DSCH) so that a DSCH
can be replaced by a HS-DSCH.
In the present invention, an indicator of whether corresponding data is
multicast data or dedicated data is added to multicast service data and
transmitted through the downlink shared channel (DSCH). The indicator is
included in a header of a MAC PDU as a target channel type field (TCTF).
Preferred embodiments of the present invention will now be
described.
Referring to the conventional downlink shared transport channel (DSCH),
a field for identifying a type of a logical channel mapped to the DSCH is not
included in the MAC header because only data of the dedicated logical channel
is transmitted. However, in order for the DSCH to provide a multicast service as
well as a dedicated service, the DSCH should support a point-to-multipoint radio
bearer (RB), for which a common logical channel, such as CTCH or MTCH,
should be mapped to DSCH.
As shown in Figure 6, the MAC PDU transmitted through DSCH consists
of an MAC header and MAC SDU. The MAC header may includes TCTF, UE ID
type, and/or an MBMS identifier (m-RNTI).
The MAC header includes a TCTF field for identifying a type of a
logical channel. The TCTF field indicates whether a channel mapped to
DSCH is a dedicated logical channel (DTCH/DCCH) or a common logical
channel (CTCH, BCCH, CCCH, MTCH, MCCH). That is, the TCTF field
indicates whether multicast service data transmitted through the downlink
shared channel (DSCH) is multicast data or dedicated data.
The UE ID type field indicates whether a type of a UE ID included in
the MAC header is U-RNTI, C-RNTI, DSCH-RNTI or the MBMS identifier (m-
RNTI).
The MBMS (m-RNTI) field indicates terminal identifier information.
Generally, for the point-to-point DSCH, DSCH-RNTI is used as a UE ID in the
MAC header, whereas for the point-to-multipoint DSCH, the MBMS identifier (m-
RNTI) is used as the UE ID. Alternatively, instead of the MBMS identifier, an
MBMS service identifier or a terminal group identifier may be used as the UE ID.
Accordingly, UTRAN MAC attaches MAC header information to the
RLC PDU transmitted through CTCH to construct a MAC PDU, that is, a
transmission block, and transmits it to the physical layer through DSCH.
Figure 7 illustrates a structure of a common type of MAC of CRNC
for the point-to-multipoint DSCH. The common type of MAC of CRNC
supports the MBMS in UTRAN. An MAC-c/sh can be used as the common
type of MAC in CRNC.
As shown in Figure 7, an RLC UM (Unacknowledged Mode) of an
RLC 10 exists in every MBMS point-to-multipoint radio bearer. Different RLC
UM entities transmit MBMS data having different QoS (Quality of Service).
One RLC UM entity has one CTCH. In Figure 7, MTCH can be also used
instead of CTCH.
Upon receiving the RLC PDU through CTCH, an MAC-c/sh 20 adds
the m-RNTI and a UE ID to the RLC PDU and performs a TCTF multiplexing
(steps S21, S23 and S24). At this time, a step S22 means a flow control
between the MAC-c/sh and an MAC-d.
Thereafter, the MAC-c/sh performs a downlink scheduling function
that suitably allocates the downlink shared channel to the terminal at every
transmission time interval (TTI) and a priority handling function that transmits
data with a higher priority first (step S25). At this time, the MAC-c/sh 20 can
perform the priority handling by the following three types.
1. Priority handling among MBMS multicast groups (or MBMS
services)
2. Priority handling on one MBMS multicast group (or one MBMS
service)
3. Priority handling among data in an MBMS multicast group (or
MBMS service)
For instance, when data of several MBMS multicast group is
transmitted through the common transport channel such as FACH, DSCH or
HS-DSCH at the downlink, the MAC-c/sh 20 transmits MBMS data with a
higher priority first. This is related to a dynamic scheduling function, and such
a method can heighten an efficiency of a channel resource by suitably
allocating the common channel to the terminal at every TTI.
In case that several logical channels belonging to one MBMS service
or one MBMS multicast group are mapped to one transport channel, the
MAC-c/sh 20 determines a priority from a logical channel priority. This is
related to a transport format combination selection, and the MAC-c/sh selects
a transport format combination (TFC) that can transmit data of a logical
channel with a higher priority first (step S26).
The MAC-c/sh selects TFCs of data to be transmitted through the
point-to-muftipoint DSCH, and selects a code of a downlink for transmitting a
corresponding MAC PDU, that is, a channel code of a PDSCH (Physical
Downlink Shared Channel) (physical channel) (step S27). in a specific
PDSCH radio frame, the PDSCH channel code is used to transmit a
corresponding MBMS service or an MBMS multicast group data.
Figure 8 illustrates a structure of a common type of MAC of a
terminal for the point-to-multipoint DSCH. The common type of MAC of a
terminal supports the MBMS in UE. An MAC-c/sh can be used as the
common type of MAC in UE.
As shown in Figure 8, a physical layer of a terminal belonging to the
MBMS multicast group first receives DSCH control information through
DPCH, and then determines whether to receive DSCH during a specific radio
frame depending on a content of the received DSCH control information.
If the DSCH control information informs that DSCH should be
received during the specific radio frame for the MBMS service, the physical
layer of the terminal receives DSCH during the specific radio frame according
to the DSCH control information, decodes the MAC PDU, and transmits it to
the MAC-c/sh of the terminal through the transport channel.
Then, the MAC-c/sh 40 of the terminal demultiplexes a TCTF field
from the received MAC PDU (step S43), and checks whether the information
of the TCTF field inserted in the MAC PDU indicates the dedicated logical
channel (DTCH or DCCH) mapping or the common logical channel (e.g.,
CTCH, MTCH or MCCH) mapping.
If the information of the TCTF field indicates the dedicated logical
channel (DTCH or DCCH) mapping, the MAC-c/sh 40 processes data in the
same manner as the point-to-point DSCH of the conventional art. That is, if
the information of the TCTF field indicates the dedicated logical channel
mapping, the MAC-c/sh of the terminal reads a UE ID from the MAC header
and discriminates whether the corresponding UE ID is its own ID. If the
corresponding UE ID is its own ID, the MAC-c/sh of the terminal transmits the
corresponding MAC PDU to the MAC-d layer.
If the information of the TCTF field inserted in the MAC PDU
indicates the common logical channel (e.g. CTCH or MTCH) mapping, the
MAC-c/sh of the terminal checks whether the UE ID type field indicates
inclusion of the MBMS RNTI (m-RNTI). If the UE ID type field does not
indicate inclusion of m-RNTI, the MAC-c/sh discards the corresponding MAC
PDU.
If, the UE ID type field indicates inclusion of m-RNTI, the MAC-c/sh
40 reads m-RNTI from the MBMS identifier field (step S43) and checks
whether the read m-RNTI indicates a multicast service that the terminal
desires to receive, if the read m-RNTI does not indicate the multicast service
that the terminal desires to receive, the MAC-c/sh 40 discards the
corresponding MAC PDU.
If the corresponding m-RNTI indicates the multicast service that the
terminal desires to receive, the MAC-c/sh 40 transmits the RLC PDU to an
RLC UM entity 31 of the RLC layer -30 of the terminal through the
corresponding common logical channel (CTCH) by using the logical channel
type (e.g., CTCH) inserted in the corresponding MAC PDU and identification
information. That is, on the basis of the TCTF inserted in the MAC PDU and
the information of the MBMS identifier field, the MAC-c/sh 40 of the terminal
can recognize from which logical channel the data (MAC PDU) has been
transmitted and through which logical channel the data is to be transmitted to
the RLC layer of the terminal.
As so far described, the method for transmitting multicast data
through a downlink shared channel of the present invention has the following
advantage. That is, by including the TCTF field in the header of the MAC
PDU that the DSCH transmits, when DSCH supports the point-to-multipoint
radio bearer, a type of a mapped logical channel can be known. Therefore,
the MAC-c/sh of the terminal that receives the DSCH data can recognize
from which logical channel the data (MAC PDU) has been transmitted and
through which logical channel the data is to be transmitted to the RLC layer
of the terminal.
The foregoing embodiments and advantages are merely exemplary
and are not to be construed as limiting the present invention. The present
teaching can be readily applied to other types of apparatuses. The
description of the present invention is intended to be illustrative, and not to
limit the scope of the claims. Many alternatives, modifications, and variations
will be apparent to those skilled in the art. In the claims, means-plus-function
clauses are intended to cover the structure described herein as performing
the recited function and not only structural equivalents but also equivalent
structures.
WE CLAIM:
1. A multicast service providing method in a wireless system, comprising:
mapping at least one logical channel to a transport channel; and
transmitting the at least one logical channel data to a receiving end through the
transport channel;
wherein the transport channel is an uni-directional shared channel, and, dedicated
logical channel data and common logical channel data are transmitted through the uni-
directional shared channel, such that data of the uni-directional shared channel
contains a first indicator indicating a logical channel type and a second indicator
indicating the multicast service, whereby the dedicated logical channel data and the
common logical channel data are capable of being identified at the receiving end.
2. The method as claimed in claim 1, wherein the dedicated logical channel is a
dedicated traffic channel (DTCH) or a dedicated control channel (DCCH).
3. The method as claimed in claim 1, wherein the dedicated logical channel data
are multimedia broadcast/multicast service (MBMS) data.
4. The method as claimed in claim 1, wherein the common logical channel is an
MBMS traffic channel (MTCH) or an MBMS control channel (MCCH).
5. The method as claimed in claim 1, wherein the first indicator is a target channel
type field (TCTF).
6. The method as claimed in claim 1, wherein the shared channel is a downlink
shared channel (DSCH).
7. The method as claimed in claim 1, wherein the shared channel is a channel that
transmits a data only.
8. The method as claimed in claim 1, wherein a control of the shared channel is a
channel of which control information is transmitted through an associated channel.
9. The method as claimed in claim 1, wherein the data of the shared channel also
contains a service data unit.

A method of communicating with a plurality of mobile terminals in a wireless
communication system, network performing the method by using a MAC entity (20)
therein, and a mobile terminal performing the method by using a MAC entity (40)
therein are provided to solve the problems of not being able to distinguish the types of
service data when common logical channel data is transmitted through a dedicated
shred channel. The method comprises: mapping at least one logical channel to a
transport channel; and
transmitting the at least one logical channel data to a receiving end through the
transport channel; wherein the transport channel is an uni-directional shared channel,
and, dedicated logical channel data and common logical channel data are transmitted
through the uni-directional shared channel, such that data of the uni-directional shared
channel contains a first indicator indicating a logical channel type and a second
indicator indicating the multicast service, whereby the dedicated logical channel data
and the common logical channel data are capable of being identified at the receiving
end.

Documents:

827-kolnp-2004-abstract.pdf

827-kolnp-2004-assignment.pdf

827-kolnp-2004-assignment1.1.pdf

827-kolnp-2004-claims.pdf

827-KOLNP-2004-CORRESPONDENCE 1.2.pdf

827-KOLNP-2004-CORRESPONDENCE-1.1.pdf

827-kolnp-2004-correspondence.pdf

827-kolnp-2004-correspondence1.1.pdf

827-kolnp-2004-description (complete).pdf

827-kolnp-2004-drawings.pdf

827-kolnp-2004-examination report.pdf

827-kolnp-2004-examination report1.1.pdf

827-kolnp-2004-form 1.pdf

827-kolnp-2004-form 13.1.pdf

827-kolnp-2004-form 13.pdf

827-kolnp-2004-form 18.1.pdf

827-kolnp-2004-form 18.pdf

827-kolnp-2004-form 2.pdf

827-kolnp-2004-form 3.1.pdf

827-kolnp-2004-form 3.pdf

827-kolnp-2004-form 5.1.pdf

827-kolnp-2004-form 5.pdf

827-KOLNP-2004-FORM-27.pdf

827-kolnp-2004-gpa.pdf

827-kolnp-2004-gpa1.1.pdf

827-kolnp-2004-granted-abstract.pdf

827-kolnp-2004-granted-claims.pdf

827-kolnp-2004-granted-description (complete).pdf

827-kolnp-2004-granted-drawings.pdf

827-kolnp-2004-granted-form 1.pdf

827-kolnp-2004-granted-specification.pdf

827-kolnp-2004-others.pdf

827-kolnp-2004-reply to examination report.pdf

827-kolnp-2004-reply to examination report1.1.pdf

827-kolnp-2004-specification.pdf

827-kolnp-2004-translated copy of priority document.pdf

827-kolnp-2004-translated copy of priority document1.1.pdf


Patent Number 244350
Indian Patent Application Number 827/KOLNP/2004
PG Journal Number 49/2010
Publication Date 03-Dec-2010
Grant Date 02-Dec-2010
Date of Filing 15-Jun-2004
Name of Patentee LG ELECTRONICS INC.
Applicant Address 20, YOIDO-DONG, YOUNGDUNGPO-GU, 150-010 SEOUL
Inventors:
# Inventor's Name Inventor's Address
1 YI SEUNG-JUNE DAECHOENG APT. 303-403, GAEPO-DONG, GANGNAM-GU, SEOUL 135-940
2 LEE SO-YOUNG TWEGYE 2ND APT. 366-702, OGEUM-DONG, GUNPO, GYEONGGI-DO, 435-758
3 LEE YOUNG-DAE SINAN APT. 419-501,CHANGWOO-DONG, HANAM, GYEONGGI-DO 465-711
PCT International Classification Number H04B 7/26
PCT International Application Number PCT/KR2003/001919
PCT International Filing date 2003-09-19
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10-2002-0057459 2002-09-19 Republic of Korea