U.S. patent application number 11/202666 was filed with the patent office on 2006-02-23 for timing of point-to-multipoint control channel information.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Myeong-Cheol Kim.
Application Number | 20060040655 11/202666 |
Document ID | / |
Family ID | 36060245 |
Filed Date | 2006-02-23 |
United States Patent
Application |
20060040655 |
Kind Code |
A1 |
Kim; Myeong-Cheol |
February 23, 2006 |
Timing of point-to-multipoint control channel information
Abstract
The present invention is directed to notifying a mobile
terminal, on a control channel MCCH and an indication channel MICH
during a modification period, the presence of control information
on the control channel MCCH during a subsequent modification
period. Specifically, the mobile terminal subscribes to at least
one point-to-multipoint service, receives first point-to-multipoint
control information related to a first point-to-multipoint service
on a point-to-multipoint control channel during a first
modification period, and receives notification information on the
point-to-multipoint control during the first modification period
for indicating the presence of second point-to-multipoint control
information related to a second point-to-multipoint service during
a second modification period.
Inventors: |
Kim; Myeong-Cheol; (Aachen,
DE) |
Correspondence
Address: |
LEE, HONG, DEGERMAN, KANG & SCHMADEKA;14th Floor
801 S. Figueroa Street
Los Angeles
CA
90017
US
|
Assignee: |
LG Electronics Inc.
|
Family ID: |
36060245 |
Appl. No.: |
11/202666 |
Filed: |
August 11, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60601267 |
Aug 12, 2004 |
|
|
|
Current U.S.
Class: |
455/426.1 |
Current CPC
Class: |
H04W 76/40 20180201;
H04W 48/12 20130101; H04W 68/00 20130101; H04W 72/005 20130101 |
Class at
Publication: |
455/426.1 |
International
Class: |
H04Q 7/20 20060101
H04Q007/20 |
Claims
1. A method for receiving a point-to-multipoint service in a
wireless communication system, the method comprising: subscribing
to at least one point-to-multipoint service; receiving first
point-to-multipoint control information related to a first
point-to-multipoint service on a point-to-multipoint control
channel during a first modification period; and receiving
notification information on the point-to-multipoint control channel
during the first modification period for indicating the presence of
second point-to-multipoint control information related to a second
point-to-multipoint service during a second modification
period.
2. The method of claim 1, wherein the point-to-multipoint control
channel is not a point-to-multipoint indication channel.
3. The method of claim 1, further comprising receiving the
notification information on a point-to-multipoint indication
channel during the first modification period.
4. The method of claim 1, further comprising receiving the second
point-to-multipoint control information on the point-to-multipoint
control channel during the second modification period.
5. The method of claim 1, wherein the second modification period is
immediately subsequent to the first modification period.
6. The method of claim 1, wherein the point-to-multipoint service
is an MBMS service.
7. The method of claim 3, wherein the point-to-multipoint
indication channel is MICH.
8. The method of claim 1, wherein the point-to-multipoint control
channel is MCCH.
9. The method of claim 1, wherein the notification information
received on the point-to-multipoint control channel comprises an
information element that indicates whether a mobile terminal should
continue reading the point-to-multipoint control channel during the
second modification period.
10. The method of claim 9, wherein the information element is a
CONTINUE MCCH READING information element.
11. The method of claim 9, wherein the information element is
contained in a message transmitted periodically by a network to
inform at least one mobile terminal about a change applicable to at
least one point-to-multipoint service available in a current cell
or neighboring cell.
12. The method of claim 11, wherein the message is a MBMS MODIFIED
SERVICES INFORMATION message.
13. A method for transmitting a point-to-multipoint service in a
wireless communication system, the method comprising: transmitting
first point-to-multipoint control information related to a first
point-to-multipoint service on a point-to-multipoint control
channel during a first modification period; and transmitting
notification information on the point-to-multipoint control channel
during the first modification period for indicating the presence of
second point-to-multipoint control information related to a second
point-to-multipoint service during a second modification
period.
14. The method of claim 1, wherein the point-to-multipoint control
channel is not a point-to-multipoint indication channel.
15. The method of claim 13, further comprising transmitting the
notification information on a point-to-multipoint indication
channel during the first modification period.
16. The method of claim 13, further comprising transmitting the
second point-to-multipoint control information on the
point-to-multipoint control channel during the second modification
period.
17. The method of claim 13, wherein the second modification period
is immediately subsequent to the first modification period.
18. The method of claim 13, wherein the point-to-multipoint service
is an MBMS service.
19. The method of claim 15, wherein the point-to-multipoint
indication channel is MICH.
20. The method of claim 13, wherein the point-to-multipoint control
channel is MCCH.
21. The method of claim 13, wherein the notification information
transmitted on the point-to-multipoint control channel comprises an
information element that indicates whether a mobile terminal should
continue reading the point-to-multipoint control channel during the
second modification period.
22. The method of claim 21, wherein the information element is a
CONTINUE MCCH READING information element.
23. The method of claim 21, wherein the information element is
contained in a message transmitted periodically by a network to
inform at least one mobile terminal about a change applicable to at
least one point-to-multipoint service available in a current cell
or neighboring cell.
24. The method of claim 23, wherein the message is a MBMS MODIFIED
SERVICES INFORMATION message.
25. The method of claim 13, wherein the notification information is
transmitted periodically on the point-to-multipoint control channel
during the entire first modification period.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C. .sctn. 119(e), this application claims
the benefit of earlier filing date and right of priority to U.S.
Provisional Application No. 60/601,267, filed on Aug. 12, 2004, the
contents of which is hereby incorporated by reference herein in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to indicating to a mobile
terminal the presence of control information, and more
particularly, to notifying a mobile terminal, on a control channel
and an indication channel during a modification period, the
presence of control information on the control channel during a
subsequent modification period.
BACKGROUND OF THE INVENTION
[0003] Recently, mobile communication systems have developed
remarkably, but for high capacity data communication services, the
performance of mobile communication systems cannot match that of
existing wired communication systems. Accordingly, technical
developments for IMT-2000, which is a communication system allowing
high capacity data communications, are being made and
standardization of such technology is being actively pursued among
various companies and organizations.
[0004] A universal mobile telecommunication system (UMTS) is a
third generation mobile communication system that has evolved from
a European standard known as Global System for Mobile
communications (GSM). The UMTS aims to provide improved mobile
communication service based on a GSM core network and wideband code
division multiple access (W-CDMA) wireless connection
technology.
[0005] In December 1998, ETSI of Europe, ARIB/TTC of Japan, T1 of
the United States, and TTA of Korea formed a Third Generation
Partnership Project (3GPP) for creating the detailed specifications
of the UMTS technology.
[0006] Within the 3GPP, in order to achieve rapid and efficient
technical development of the UMTS, five technical specification
groups (TSG) have been created for performing the standardization
of the UMTS by considering the independent nature of the network
elements and their operations.
[0007] 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.
[0008] FIG. 1 illustrates an exemplary basic structure of a general
UMTS network. As shown in FIG. 1, the UMTS is roughly divided into
a mobile terminal (or user equipment: UE) 10, a UTRAN 100, and a
core network (CN) 200.
[0009] The UTRAN 100 includes one or more radio network sub-systems
(RNS) 110, 120. Each RNS 110, 120 includes a radio network
controller (RNC) 111, and a plurality of base stations or Node-Bs
112, 113 managed by the RNC 111. The RNC 111 handles the assigning
and managing of radio resources, and operates as an access point
with respect to the core network 200.
[0010] The Node-Bs 112, 113 receive information sent by the
physical layer of the terminal through an uplink, and transmit data
to the terminal through a downlink. The Node-Bs 112, 113, thus,
operate as access points of the UTRAN 100 for the terminal. Each
NodeB controls one or several cells, where a cell covers a given
geographical area on a given frequency. Each RNC is connected via
the lu interface to the CN, i.e. towards the MSC (Mobile-services
Switching Centre) entity of the CN and the SGSN (Serving GPRS
Support Node) entity. RNCs can be connected to other RNCs via the
lur interface. The RNC handles the assignment and management of
radio resources and operates as an access point with respect to the
core network.
[0011] The NodeBs receive information sent by the physical layer of
the terminal through an uplink and transmit data to the terminal
through a downlink. The NodeBs operate as access points of the
UTRAN for the terminal. The SGSN is connected via the Gf interface
to the EIR (Equipment Identity Register), via the G.sub.S interface
to the MSC, via the G.sub.N interface to the GGSN (Gateway GPRS
Support Node) and via the G.sub.R interface to the HSS (Home
Subscriber Server). The EIR hosts lists of mobile terminals which
are allowed or are not allowed to be used on the network. The MSC,
which controls the connection for CS services is connected via the
N.sub.B interface towards the MGW (Media Gateway), via the F
interface towards the EIR, and via the D interface towards the HSS.
The MGW is connected via the C interface towards the HSS, and to
the PSTN (Public Switched Telephone Network), and allows to adapt
the codecs between the PSTN and the connected RAN.
[0012] The GGSN is connected via the G.sub.C interface to the HSS,
and via the G.sub.I interface to the Internet. The GGSN is
responsible for routing, charging and separation of data flows into
different RABs. The HSS handles the subscription data of the
users.
[0013] A primary function of the UTRAN 100 is forming and
maintaining a radio access bearer (RAB) to allow communication
between the terminal and the core network 200. The core network 200
applies end-to-end quality of service (QoS) requirements to the
RAB, and the RAB supports the QoS requirements set by the core
network 200. As the UTRAN 100 forms and maintains the RAB, the QoS
requirements of end-to-end are satisfied. The RAB service can be
further divided into an lu bearer service and a radio bearer
service. The lu bearer service supports a reliable transmission of
user data between boundary nodes of the UTRAN 100 and the core
network 200.
[0014] The core network 200 includes a mobile switching center
(MSC) 210 and a gateway mobile switching center (GMSC) 220
connected together for supporting a circuit switched (CS) service,
and a serving GPRS support node (SGSN) 230 and a gateway GPRS
support node 240 connected together for supporting a packet
switched (PS) service.
[0015] The services provided to a specific terminal are roughly
divided into the circuit switched (CS) services and the packet
switched (PS) 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.
[0016] For supporting circuit switched services, the RNCs 111 are
connected to the MSC 210 of the core network 200, and the MSC 210
is connected to the GMSC 220 that manages the connection with other
networks.
[0017] For supporting packet switched services, the RNCs 111 are
connected to the SGSN 230 and the GGSN 240 of the core network 200.
The SGSN 230 supports the packet communications going toward the
RNCs 111, and the GGSN 240 manages the connection with other packet
switched networks, such as the Internet.
[0018] Various types of interfaces exist between network components
to allow the network components to transmit and receive information
to and from each other for mutual communication therebetween. An
interface between the RNC 111 and the core network 200 is defined
as an lu interface. In particular, the lu interface between the
RNCs 111 and the core network 200 for packet switched systems is
defined as "lu-PS," and the lu interface between the RNCs 111 and
the core network 200 for circuit switched systems is defined as
"lu-CS."
[0019] FIG. 2 illustrates a structure of a radio interface protocol
between the terminal and the UTRAN according to the 3GPP radio
access network standards.
[0020] As shown in FIG. 2, the radio interface protocol has
horizontal layers comprising a physical layer, a data link layer,
and a network layer, and has vertical planes comprising a user
plane (U-plane) for transmitting user data and a control plane
(C-plane) for transmitting control information.
[0021] The user plane is a region that handles traffic information
of the user, such as voice or Internet protocol (IP) packets, while
the control plane is a region that handles control information for
an interface of a network, maintenance and management of a call,
and the like.
[0022] The protocol layers in FIG. 2 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. Each layer will be described in more detail as follows.
[0023] The first layer (L1), namely, the physical layer, provides
an information transfer service to an upper layer by using various
radio transmission techniques. The physical layer is connected to
an upper layer called a medium access control (MAC) layer, via a
transport channel. The MAC layer and the physical layer send and
receive data with one another via the transport channel.
[0024] 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.
[0025] The MAC layer provides an allocation service of the MAC
parameters for allocation and re-allocation of radio resources. The
MAC layer is connected to an upper layer called the radio link
control (RLC) layer, via a logical channel.
[0026] 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. A logical channel may be a common channel or a dedicated
channel depending on whether the logical channel is shared. Logical
channels include a dedicated traffic channel (DTCH), a dedicated
control channel (DCCH), a common traffic channel (CTCH), a common
control channel (CCCH), a broadcast control channel (BCCH) and a
paging control channel (PCCH) or a Shared Channel Control Channel
(SHCCH). The BCCH provides information including information
utilized by a terminal to access a system. The PCCH is used by the
UTRAN to access a terminal.
[0027] A Multimedia Broadcast/Multicast Service (MBMS or "MBMS
service") refers to a method of providing streaming or background
services to a plurality of UEs using a downlink-dedicated MBMS
radio bearer that utilizes at least one of point-to-multipoint and
point-to-point radio bearer. One MBMS service includes one or more
sessions and MBMS data is transmitted to the plurality of terminals
through the MBMS radio bearer only while the session is
ongoing.
[0028] As the name implies, an MBMS may be carried out in a
broadcast mode or a multicast mode. The broadcast mode is for
transmitting multimedia data to all UEs within a broadcast area,
for example the domain where the broadcast is available. The
multicast mode is for transmitting multimedia data to a specific UE
group within a multicast area, for example the domain where the
multicast service is available.
[0029] For purposes of MBMS, additional traffic and control
channels exist. For example, an MCCH (MBMS point-to-multipoint
Control Channel) is used for transmitting MBMS control information
while an MTCH (MBMS point-to-multipoint Traffic Channel) is used
for transmitting MBMS service data.
[0030] The different logical channels that exist are listed below:
##STR1##
[0031] The MAC layer is connected to the physical layer by
transport channels and can be divided into a MAC-b sub-layer, a
MAC-d sub-layer, a MAC-c/sh sub-layer, and a MAC-hs sub-layer
according to the type of transport channel to be managed.
[0032] The MAC-b sub-layer manages a BCH (Broadcast Channel), which
is a transport channel handling the broadcasting of system
information. The MAC-d sub-layer manages a dedicated channel (DCH),
which is a dedicated transport channel for a specific terminal.
Accordingly, the MAC-d sub-layer of the UTRAN is located in a
serving radio network controller (SRNC) that manages a
corresponding terminal, and one MAC-d sub-layer also exists within
each terminal (UE).
[0033] The MAC-c/sh sub-layer manages a common transport channel,
such as a forward access channel (FACH) or a downlink shared
channel (DSCH), which is shared by a plurality of terminals, or in
the uplink the Radio Access Channel (RACH). In the UTRAN, the
MAC-c/sh sub-layer is located in a controlling radio network
controller (CRNC). As the MAC-c/sh sub-layer manages the channel
being shared by all terminals within a cell region, a single
MAC-c/sh sub-layer exists for each cell region. Also, one MAC-c/sh
sublayer exists in each terminal (UE). Referring to FIG. 3,
possible mapping between the logical channels and the transport
channels from a UE perspective is shown. Referring to FIG. 4,
possible mapping between the logical channels and the transport
channels from a UTRAN perspective is shown.
[0034] The RLC layer supports reliable data transmissions, and
performs a segmentation and concatenation function on a plurality
of RLC service data units (RLC SDUs) delivered from an upper layer.
When the RLC layer receives the RLC SDUs from the upper layer, the
RLC layer adjusts the size of each RLC SDU in an appropriate manner
upon considering processing capacity, and then creates certain data
units with header information added thereto. The created data units
are called protocol data units (PDUs), which are then transferred
to the MAC layer via a logical channel. The RLC layer includes a
RLC buffer for storing the RLC SDUs and/or the RLC PDUs.
[0035] The BMC layer schedules a cell broadcast message (referred
to as a `CB message`, hereinafter) received from the core network,
and broadcasts the CB messages to terminals located in a specific
cell(s). The BMC layer of the UTRAN generates a broadcast/multicast
control (BMC) message by adding information, such as a message ID
(identification), a serial number, and a coding scheme to the CB
message received from the upper layer, and transfers the BMC
message to the RLC layer. The BMC messages are transferred from the
RLC layer to the MAC layer through a logical channel, i.e., the
CTCH (Common Traffic Channel). The CTCH is mapped to a transport
channel, i.e., a FACH, which is mapped to a physical channel, i.e.,
a S-CCPCH (Secondary Common Control Physical Channel).
[0036] The PDCP (Packet Data Convergence Protocol) layer, as a
higher layer of the RLC layer, allows the data transmitted through
a network protocol, such as an IPv4 or IPv6, to be effectively
transmitted on a radio interface with a relatively small bandwidth.
To achieve this, the PDCP layer reduces unnecessary control
information used in a wired network, a function called header
compression.
[0037] A radio resource control (RRC) layer is located at a
lowermost portion of the L3 layer. The RRC layer is defined only in
the control plane, and handles the control of logical channels,
transport channels, and physical channels with respect to setup,
reconfiguration, and release or cancellation of radio bearers
(RBs). The radio bearer service refers to a service provided by the
second layer (L2) for data transmission between the terminal and
the UTRAN. In general, the setup of the radio bearer refers to the
process of defining the characteristics of a protocol layer and a
channel required for providing a specific data service, as well as
respectively setting detailed parameters and operation methods.
[0038] The RLC layer can 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. That is, 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.
[0039] The different possibilities that exist for the mapping
between the radio bearers and the transport channels are not always
possible. The UE/UTRAN deduces the possible mapping depending on
the UE state and the procedure that the UE/UTRAN is executing. The
different states and modes are explained in more detail below.
[0040] The different transport channels are mapped onto different
physical channels. For example, the RACH transport channel is
mapped on a given PRACH, the DCH can be mapped on the DPCH, the
FACH and the PCH can be mapped on the S-CCPCH, the DSCH is mapped
on the PDSCH and so on. The configuration of the physical channels
is given by an RRC signaling exchange between the RNC and the
UE.
[0041] The RRC mode refers to whether there exists a logical
connection between the RRC of the terminal and the RRC of the
UTRAN. If there is a connection, the terminal is said to be in RRC
connected mode. If there is no connection, the terminal is said to
be in idle mode. Because an RRC connection exists for terminals in
RRC connected mode, the UTRAN can determine the existence of a
particular terminal within the unit of cells, for example which
cell or set of cells the RRC connected mode terminal is in, and
which physical channel the UE is listening to. Thus, the terminal
can be effectively controlled.
[0042] In contrast, the UTRAN cannot determine the existence of a
terminal in idle mode. The existence of idle mode terminals can
only be determined by the core network. Specifically, the core
network can only detect the existence of idle mode terminals within
a region that is larger than a cell, such as a location or a
routing area. Therefore, the existence of idle mode terminals is
determined within large regions. In order to receive mobile
communication services such as voice or data, the idle mode
terminal must move or change into the RRC connected mode. The
possible transitions between modes and states are shown in FIG.
5.
[0043] A UE in RRC connected mode can be in different states, such
as a CELL_FACH state, a CELL_PCH state, a CELL_DCH state or a
URA_PCH state. Depending on the states, the UE listens to different
channels. For example a UE in CELL_DCH state will try to listen
(amongst others) to DCH type of transport channels, which comprises
DTCH and DCCH transport channels, and which can be mapped to a
certain DPCH. The UE in CELL_FACH state will listen to several FACH
transport channels which are mapped to a certain S-CCPCH physical
channel. The UE in PCH state will listen to the PICH channel and to
the PCH channel, which is mapped to a certain S-CCPCH physical
channel.
[0044] The UE also carries out different actions depending on the
state. For example, based on different conditions, a UE in
CELL_FACH will start a CELL Update procedure each time the UE
changes from the coverage of one cell into the coverage of another
cell. The UE starts the CELL Update procedure by sending to the
NodeB a Cell Update message to indicate that the UE has changed its
location. The UE will then start listening to the FACH. This
procedure is additionally used when the UE comes from any other
state to CELL_FACH state and the UE has no C-RNTI available, such
as when the UE comes from the CELL_PCH state or CELL_DCH state, or
when the UE in CELL_FACH state was out of coverage.
[0045] In the CELL_DCH state, the UE is granted dedicated radio
resources, and may additionally use shared radio resources. This
allows the UE to have a high data rate and efficient data exchange.
However, the radio resources are limited. It is the responsibility
of the UTRAN to allocate the radio resources amongst the UEs such
that they are efficiently used and ensure that the different UEs
obtain the quality of service required.
[0046] A UE in CELL_FACH state has no dedicated radio resources
attributed, and can only communicate with the UTRAN via shared
channels. Thus, the UE consumes few radio resources. However, the
data rate available is very limited. Also, the UE needs to
permanently monitor the shared channels. Thus, UE battery
consumption is increased in the case where the UE is not
transmitting.
[0047] A UE in CELL_PCH/URA_PCH state only monitors the paging
channel at dedicated occasions, and therefore minimizes the battery
consumption. However, if the network wishes to access the UE, it
must first indicate this desire on the paging occasion. The network
may then access the UE, but only if the UE has replied to the
paging. Furthermore, the UE can only access the network after
performing a Cell Update procedure which introduces additional
delays when the UE wants to send data to the UTRAN.
[0048] Generally, a UE in CELL_DCH state simultaneously exchanges
data with different cells of NodeBs using a DPCCH (Dedicated
Physical Control Channel). The different cells the UE is connected
to, i.e., the cells to which the UE transmits to or receives from
the DPCCH channel may belong to the same or different NodeBs. The
different NodeBs may be connected to one RNC or to different RNCs.
When a UE exchanges data with a cell in CELL_DCH state, the UE is
said to have a radio link towards a cell. When the UE has radio
links to several NodeBs, the UE is said to be in "soft handover".
When the UE has radio links to several cells on the same NodeB, the
UE is said to be in "softer handover". The set of all radio links
the UE Uses is called the "active set" of the UE. The UE may
receive information on the neighboring cells via signaling messages
to evaluate cell quality and report this information to the RNC.
The RNC may then use this information to update the list of cells
in the active set of the UE.
[0049] Main system information is sent on the BCCH logical channel,
which is mapped on the P-CCPCH (Primary Common Control Physical
Channel). Specific system information blocks can be sent on the
FACH channel. When the system information is sent on the FACH, the
UE receives the configuration of the FACH either on the BCCH that
is received on the P-CCPCH or on a dedicated channel. The P-CCPCH
is sent using the same scrambling code as a P-CPICH (Primary Common
Pilot Channel), which is the primary scrambling code of the cell.
Each channel uses a spreading code as commonly done in WCDMA
(Wideband Code Division Multiple Access) systems. Each code is
characterized by its spreading factor (SF), which corresponds to
the length of the code. For a given spreading factor, the number of
orthogonal codes is equal to the length of the code. For each
spreading factor, the given set of orthogonal codes, as specified
in the UMTS system, are numbered from 0 to SF-1. Each code can thus
be identified by giving its length (i.e. spreading factor) and the
number of the code. The spreading code that is used by the P-CCPCH
is always of a fixed spreading factor 256 and the number is the
number 1. The UE knows about the primary scrambling code either by
information sent from the network on system information of
neighboring cells that the UE has read, by messages that the UE has
received on the DCCH channel, or by searching for the P-CPICH,
which is sent using the fixed SF 256 and the spreading code number
0, and which transmits a fixed pattern.
[0050] The system information comprises information on neighboring
cells, configuration of the RACH and FACH transport channels, and
the configuration of MCCH, which is a channel dedicated for MBMS
service. When the UE has selected a cell (in CELL_FACH, CELL_PCH or
URA_PCH state), the UE verifies that it has valid system
information.
[0051] The system information is organized in SIBs (system
information blocks), a MIB (Master information block) and
scheduling blocks. The MIB is sent very frequently and provides
timing information of the scheduling blocks and the different SIBs.
For SIBs that are linked to a value tag, the MIB also contains
information on the last version of a part of the SIBs. SIBs that
are not linked to a value tag are linked to an expiration timer.
The SIBs linked to an expiration timer become invalid and need to
be reread if the time of the last reading of the SIB is larger than
an expiration timer value. The SIBs linked to a value tag are only
valid if they have the same value tag as a value tag broadcast in
the MIB. Each block has an area scope of validity, such as a Cell,
a PLMN (Public Land Mobile Network) or an equivalent PLMN, which
signifies on which cells the SIB is valid. A SIB with the area
scope "Cell" is valid only for the cell in which it has been read.
A SIB with the area scope "PLMN" is valid in the whole PLMN. A SIB
with the area scope "equivalent PLMN" is valid in the whole PLMN
and equivalent PLMN.
[0052] In general, UEs read the system information when they are in
idle mode, CELL_FACH state, CELL_PCH state or in URA_PCH state of
the cell that they have selected, i.e., the cell that they are
camping on. In the system information, the UEs receive information
on the neighboring cells on the same frequency, different
frequencies and different RAT (Radio access technologies). This
allows the UEs to know which cells are candidates for cell
reselection.
[0053] In CELL_DCH state, the UE already listens to different radio
links the UE is using. Accordingly, it increases complexity for the
UE to additionally read BCCH channels. Therefore, the UE generally
receives information on neighboring cells in a dedicated message
from the RNC, and only for some very specific functions. However,
it is possible that UEs read system information sent on the P-CCPCH
channel or other transport channels while in CELL_DCH state.
[0054] The 3GPP system can provide multimedia broadcast multicast
service (MBMS). The 3GPP TSG SA (Service and System Aspect) defines
various network elements and their functions required for
supporting MBMS services. A cell broadcast service provided by the
prior art is limited to a service in which text type short messages
are broadcast to a certain area. The MBMS service, however, is a
more advanced service that multicasts multimedia data to terminals
(UEs) that have subscribed to the corresponding service in addition
to broadcasting multimedia data.
[0055] The MBMS service is a downward-dedicated service that
provides a streaming or background service to a plurality of
terminals by using a common or dedicated downward channel. The MBMS
service is divided into a broadcast mode and a multicast mode. The
MBMS broadcast mode facilitates transmitting multimedia data to
every user located in a broadcast area, whereas the MBMS multicast
mode facilitates transmitting multimedia data to a specific user
group located in a multicast area. The broadcast area signifies a
broadcast service available area and the multicast area signifies a
multicast service available area.
[0056] FIG. 6 illustrates a process of providing a particular MBMS
service, by using the multicast mode. The procedure can be split
into two types of actions, those that are transparent and those
that are not transparent to the UTRAN.
[0057] The transparent actions are described in the following. A
user desiring to receive the MBMS service, first needs to subscribe
in order to be allowed to receive MBMS services, to receive
information on MBMS services, and to join a certain set of MBMS
services. A service announcement provides the terminal with a list
of services to be provided and other related information. The user
can then join these services. By joining, the user indicates that
the user wants to receive information linked to services that the
user has subscribed to and becomes part of a multicast service
group. When a user is no longer interested in a given MBMS service,
the user leaves the service, i.e., the user is no longer part of
the multicast service group. These actions can be taken by using
any means of communication, i.e., the actions may be done using SMS
(Short Messaging Service), or by Internet access. These actions do
not have to necessarily be done using the UMTS system.
[0058] In order to receive a service for which the user is in a
multicast group the following actions that are not transparent to
the UTRAN are executed. The SGSN informs the RNC about a session
start. Then the RNC notifies the UEs of the multicast group that a
given service has started in order to initiate reception of the
given service. After having broadcast the necessary UE actions and
eventually the configuration of the PtM bearers for the given
service the transmission of the data starts. When the session
stops, the SGSN indicates the stopped session to the RNC. The RNC
in turn initiates a session stop. The transmission of the service
from the SGSN means for the RNC to provide a bearer service for
conveying the data of the MBMS service.
[0059] After the notification procedure, other procedures can be
initiated between the UE and the RNC and the SGSN to enable data
transmission, such as RRC connection establishment, connection
establishment towards the PS domain, frequency layer convergence,
and counting.
[0060] Reception of an MBMS service may be performed in parallel to
the reception of other services, such as a voice or video call on
the CS domain, SMS transfer on the CS or PS domain, data transfer
on the PS domain, or any signaling related to the UTRAN or PS or CS
domain.
[0061] Contrary to the multicast service, for broadcast services,
as shown in FIG. 7, only the announcement of the service must be
done in a transparent manner. No subscription or joining is needed.
Afterwards, the actions that are transparent to the RNC are the
same as for multicast services.
[0062] Referring to FIG. 8, a typical session sequence from a UTRAN
perspective is illustrated. As shown, the SGSN informs the RNC
about a session start (step 1). The RNC may then perform a counting
procedure, which triggers some UEs to establish a connection to the
PS domain (step 2). Consequently, the establishment of an RRC
connection for the UEs is initiated. This allows the RNC to
estimate the number of UEs in a given cell that are interested in
the service. When the UE has established the PS connection, the
SGSN initiates the lu linking procedure, which provides the list of
multicast services the UE has joined to the RNC.
[0063] For UEs that have an RRC connection established, and which
are interested in the given MBMS service but are not connected to
the PS domain, the RNC sends a specific message to the UEs
triggering them to establish a PS connection (step 3). When the UE
has established the PS connection, the SGSN initiates the lu
linking procedure, which provides the list of multicast services
the UE has joined to the RNC. For UEs that are not in a CELL_DCH
state, a frequency layer convergence scheme allows the RNC to
trigger the UEs to change the frequency to which they listen (step
4).
[0064] Depending on the Radio Resource Management (RRM) scheme, the
RNC establishes point-to-multipoint (PtM) or point-to-point (PtP)
radio bearers for delivering the MBMS service (step 5a or 5b). The
RNC delivers data received from the SGSN to the UEs that are part
of the multicast group. After the transmission of the data, the
SGSN informs the RNC about the end of the sessions (step 6). The
RNC then releases the PtP or PtM radio bearers used for
transmitting the MBMS data (step 7a or 7b).
[0065] Generally, for UEs in an RRC connected state, two
possibilities exist. The UE will either have a connection
established with the PS domain (PMM connected) or the UE will have
no connection established with the PS domain (PMM idle mode). When
there is no connection established with the PS domain, the UE will
normally have a connection with the CS domain. Otherwise, the UE is
not in an RRC connected mode.
[0066] For MBMS, two additional control channels are introduced.
They are the MCCH and the MICH (MBMS Notification Indicator
Channel). As explained above, the MCCH is mapped on the FACH. The
MICH is a new physical channel and is used to notify users to read
the MCCH channel. The MICH is designed to allow the UEs to perform
a DRX (Discontinuous Reception) scheme. DRX allows the reduction of
battery consumption for UEs while allowing the UEs to still be
aware of any service for which a session is starting. The MICH may
be used to inform the UE of a change in a frequency convergence
scheme, change of a configuration of a point-to-multipoint (PtM)
bearer, switch between the PtM bearer and a point-to-point (PtP)
bearer, etc., which all require the MCCH to be read.
[0067] The MCCH channel periodically transmits information
regarding active services, MTCH configuration, frequency
convergence, etc. The UE reads the MCCH information to receive the
subscribed services based on different triggers. For example, the
UE may be triggered after cell selection/reselection, when the UE
is notified of a given service on the MICH, or when the UE is
notified via the DCCH channel. The configuration of the MCCH
channel is broadcast in the system information. The MICH
configuration (i.e. spreading code, scrambling code, spreading
factor and other information) is either fixed in the standard,
given in the system information or broadcast on the MCCH.
[0068] The MCCH information is transmitted based on a fixed
schedule. The schedule identifies a transmission time interval
(TTI) containing the beginning of the MCCH information. The
transmission of the information may take a variable number of TTIs.
The UTRAN transmits the MCCH information in consecutive TTIs. The
mobile terminal (UE) continues to receive the SCCPCH until: 1) the
UE receives all of the MCCH information; 2) the UE receives a TTI
that does not include any MCCH data; or 3) the information contents
indicate that further reception is not required (e.g. there is no
modification to the desired service information).
[0069] Based on this behavior, the UTRAN may repeat the MCCH
information following a scheduled transmission in order to improve
reliability. The MCCH schedule is common for all services. The
entire MCCH information is transmitted periodically based on a
"repetition period". A "modification period" is defined as an
integer multiple of the repetition period. The MBMS ACCESS
INFORMATION may be transmitted periodically based on an "access
info period". This period is an integer divider of the "repetition
period".
[0070] MCCH information may be categorized as critical and
non-critical information. The critical information is made up of
MBMS COMMON P-T-M RB INFORMATION, MBMS CURRENT CELL P-T-M RB
INFORMATION, MBMS GENERAL INFORMATION, MBMS MODIFIED SERVICES
INFORMATION, MBMS NEIGHBORING CELL P-T-M RB INFORMATION and MBMS
UNMODIFIED SERVICES INFORMATION. The non-critical information
corresponds to the MBMS ACCESS INFORMATION.
[0071] Changes to critical information on the MCCH are only applied
at beginning of the first MCCH transmission of a modification
period. At the beginning of each modification repetition period,
the UTRAN transmits the MBMS CHANGE INFORMATION including, amongst
others, information on MBMS services whose MCCH information is
modified at that modification period. MBMS CHANGE INFORMATION is
repeated at least once in each repetition period of that
modification period. Changes to non-critical information may take
place at any time. FIG. 9 illustrates a schedule with which the
MBMS CHANGE INFORMATION and RADIO BEARER INFORMATION sent on MCCH
are transmitted. Different patterned blocks indicate potentially
different MCCH content.
[0072] When a UE in CELL_FACH state wants to receive a PtM radio
bearer, the UE first needs to receive the system information on the
BCCH channel, which is sent on the P-CCPCH channel, to know the
MCCH configuration of the cell the UE has selected. Therefore, the
UE must know the primary scrambling code. Once the UE knows the
MCCH channel configuration, the UE then reads the MCCH channel to
obtain configuration information of the PtM radio bearers. To
obtain a first starting cell, the UE may receive the primary
scrambling code of the cell by dedicated messages. The UE may also
perform a cell search or read stored information. Alternatively,
for a UE that has already selected or camped on a cell, the UE may
use information regarding neighboring cells found in the system
information of the cell the UE has already selected.
[0073] MBMS control information is sent on the MCCH. To allow the
UE to perform discontinuous reception (DRX) on the reception of the
MCCH, another channel, such as the MICH, is used to indicate when
the UE must read MCCH. This may occur when the content of the MCCH
changes.
[0074] Accordingly, the UE may read the MICH and MCCH in parallel.
However, the UE may have to decode two channels (MICH and MCCH)
instead of just one (MICH or MCCH). Therefore, it has been proposed
that changes to information transmitted on the MCCH are signaled to
the UE in a notification message transmitted on the MICH during a
modification period before the modification period where the
changed information is transmitted on the MCCH. Referring to FIG.
10, when a new service is started, the configuration/actions to be
performed by the UE are transmitted on the MCCH during one
modification period, where the same information is sent during the
complete modification period. In order to inform the UE of the
transmission of new information on the MCCH, an indication is sent
on the MICH during a preceding modification period.
[0075] However, a problem arises when the UE wants to stop reading
the MCCH. During the last modification period of the MCCH reading,
the UE must also read the MICH in parallel because the MICH may
indicate changes that apply on the MCCH in a subsequent
modification period. Therefore, to solve this problem, the UE must
be able to read the MICH and the MCCH in parallel, wherein the MICH
is optimized for discontinuous reception (DRX) and information
transmitted on the MICH is also transmitted on the MCCH.
SUMMARY OF THE INVENTION
[0076] The present invention is directed to notifying a mobile
terminal, on a control channel and an indication channel during a
modification period, the presence of control information on the
control channel during a subsequent modification period.
[0077] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
invention. The objectives and other advantages of the invention
will be realized and attained by the structure particularly pointed
out in the written description and claims hereof as well as the
appended drawings.
[0078] To achieve these and other advantages and in accordance with
the purpose of the present invention, as embodied and broadly
described, the present invention is embodied in a method for
receiving a point-to-multipoint service in a wireless communication
system, the method comprising subscribing to at least one
point-to-multipoint service; receiving first point-to-multipoint
control information related to a first point-to-multipoint service
on a point-to-multipoint control channel during a first
modification period, and receiving notification information on the
point-to-multipoint control channel during the first modification
period for indicating the presence of second point-to-multipoint
control information related to a second point-to-multipoint service
during a second modification period. Preferably, the
point-to-multipoint control channel is not a point-to-multipoint
indication channel.
[0079] In one aspect of the invention, the method further comprises
receiving the notification information on a point-to-multipoint
indication channel during the first modification period.
[0080] In another aspect of the invention, the method further
comprises receiving the second point-to-multipoint control
information on the point-to-multipoint control channel during the
second modification period.
[0081] Preferably, the second modification period is immediately
subsequent to the first modification period. The
point-to-multipoint service is an MBMS service. The
point-to-multipoint indication channel is MICH. The
point-to-multipoint control channel is MCCH.
[0082] In a further aspect of the invention, the notification
information received on the point-to-multipoint control channel
comprises an information element that indicates whether a mobile
terminal should continue reading the point-to-multipoint control
channel during the second modification period. Preferably, the
information element is a CONTINUE MCCH READING information
element.
[0083] Also, the information element is contained in a message
transmitted periodically by a network to inform at least one mobile
terminal about a change applicable to at least one
point-to-multipoint service available in a current cell or
neighboring cell. Preferably, the message is a MBMS MODIFIED
SERVICES INFORMATION message.
[0084] In another embodiment of the present invention, a method for
transmitting a point-to-multipoint service in a wireless
communication system comprises transmitting first
point-to-multipoint control information related to a first
point-to-multipoint service on a point-to-multipoint control
channel during a first modification period and transmitting
notification information on the point-to-multipoint control channel
during the first modification period for indicating the presence of
second point-to-multipoint control information related to a second
point-to-multipoint service during a second modification period.
Preferably, the point-to-multipoint control channel is not a
point-to-multipoint indication channel.
[0085] In one aspect of the invention, the method further comprises
transmitting the notification information on a point-to-multipoint
indication channel during the first modification period.
[0086] In another aspect of the invention, the method further
comprises transmitting the second point-to-multipoint control
information on the point-to-multipoint control channel during the
second modification period.
[0087] Preferably, the second modification period is immediately
subsequent to the first modification period. The
point-to-multipoint service is an MBMS service. The
point-to-multipoint indication channel is MICH. The
point-to-multipoint control channel is MCCH.
[0088] In a further aspect of the invention, the notification
information transmitted on the point-to-multipoint control channel
comprises an information element that indicates whether a mobile
terminal should continue reading the point-to-multipoint control
channel during the second modification period. Preferably, the
information element is a CONTINUE MCCH READING information
element.
[0089] Also, the information element is contained in a message
transmitted periodically by a network to inform at least one mobile
terminal about a change applicable to at least one
point-to-multipoint service available in a current cell or
neighboring cell. Preferably, the message is a MBMS MODIFIED
SERVICES INFORMATION message.
[0090] In one aspect of the invention, the notification information
is transmitted periodically on the point-to-multipoint control
channel during the entire first modification period.
[0091] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0092] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention. Features, elements, and aspects of
the invention that are referenced by the same numerals in different
figures represent the same, equivalent, or similar features,
elements, or aspects in accordance with one or more
embodiments.
[0093] FIG. 1 is a block diagram of a general UMTS network
architecture.
[0094] FIG. 2 is a block diagram of a structure of a radio
interface protocol between a terminal and a network based on 3GPP
radio access network standards.
[0095] FIG. 3 illustrates the mapping of logical channels onto
transport channels in the mobile terminal.
[0096] FIG. 4 illustrates the mapping of logical channels onto
transport channels in the network.
[0097] FIG. 5 illustrates possible transitions between modes and
states in the UMTS network.
[0098] FIG. 6 illustrates a process of providing a particular
point-to-multipoint service using a multicast mode.
[0099] FIG. 7 illustrates a process of providing broadcast
services.
[0100] FIG. 8 illustrates a session sequence from a network
perspective.
[0101] FIG. 9 illustrates a schedule for transmitting information
on an MCCH.
[0102] FIG. 10 illustrates a schedule wherein notification for
reading MCCH during a modification period is sent on MICH during a
previous modification period.
[0103] FIG. 11 illustrates MICH timing relative to a modification
period.
[0104] FIG. 12 illustrates a schedule wherein notification for
reading MCCH during a modification period is sent on MICH and MCCH
during a previous modification period in accordance with one
embodiment of the present invention.
[0105] FIG. 13 illustrates a method for notifying a UE to read MCCH
during a modification period, wherein the notification is sent on
MICH and MCCH during a previous modification period in accordance
with one embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0106] The present invention relates to notifying to a mobile
terminal, on a control channel and an indication channel during a
modification period, the presence of control information on the
control channel during a subsequent modification period.
[0107] An MBMS notification mechanism is used to inform UEs of an
upcoming change in critical MCCH information. Notifications are
based on service groups. The mapping between service IDs and
service groups is based on a hashing mechanism. The MBMS
notification indicators are sent on an MBMS specific PICH, called
the MICH. Notifications might also be sent via dedicated signaling
to UEs using the DCCH channel. A single MICH frame is able to carry
indications for every service group.
[0108] Critical MCCH information can only be changed at the
beginning of a modification period. The MBMS notification indicator
corresponding to the service group of every affected service is set
continuously during the entire modification period preceding the
first change in MCCH information related to a given service.
Subsequent changes in the MCCH information in the next modification
period related to the same service can be signaled on the MCCH.
[0109] UEs that are not receiving any MBMS services on MTCH or on a
PtP channel are free to read the MBMS notification at any time;
however, the modification interval is long enough so that the UEs
are able to reliably detect the notification even if they only
receive the MICH during regular paging occasions.
[0110] Upon detecting the MBMS notification indication for a
service group, the UEs interested in a service corresponding to the
service group start reading the MCCH at the beginning of the next
modification period. The UE reads at least the MBMS MODIFIED
SERVICES INFORMATION.
[0111] FIG. 11 illustrates the timing relationship between the
setting of the MICH and the first MCCH critical information change.
For the MICH, a period 20, designated by a diagonal pattern,
indicates when a Notification Indicator (NI) is set for a service.
For the MCCH, differently patterned blocks indicate MCCH content
related to the notification of different services.
[0112] UEs, which are receiving MBMS service(s) on MTCH in idle
mode or in a URA_PCH, CELL_PCH, or CELL_FACH state read the MCCH at
the beginning of each modification period to receive the MBMS
MODIFIED SERVICES INFORMATION. The MBMS MODIFIED SERVICES
INFORMATION indicates, amongst others, MBMS service IDs, and
optionally, an MBMS Session ID, whose MCCH information is modified
at that modification period. If the MBMS service IDs and the MBMS
Session ID, which the UE has activated, is indicated in the MBMS
MODIFIED SERVICES INFORMATION, the UE reads the rest of the MCCH
information.
[0113] Referring to FIG. 12, in one embodiment of the present
invention, information regarding services a UE is interested in and
transmitted during a modification period B is notified to the UE
during a previous modification period A using the MICH. The
information regarding the services is also notified to the UE
during the modification period A on the MCCH. Specifically, the
MCCH, which normally carries service configuration information or
information regarding UE specific actions, is used to trigger the
UE to receive the MCCH at a subsequent modification period
simultaneously with a notification to receive the MCCH transmitted
on the MICH. This may be realized by a specific setting of
information elements (IEs) transmitted between the network and the
UE.
[0114] Referring to FIG. 13, during the modification period A, the
network indicates on the MICH that the MCCH in modification period
B will contain information on a service A, and that UEs interested
in the service A should read MCCH during the modification period B
(step 1). The transmission of this indication is repeated during
the entire modification period A. During the same modification
period A, the network also indicates on the MCCH that the MCCH in
modification period B will contain information on the service A,
and that UEs interested in the service A should read MCCH during
the modification period B (step 2).
[0115] Preferably, the indication is sent in an MBMS MODIFIED
SERVICES INFORMATION message or as a CONTINUE MCCH READING
information element. The MBMS MODIFIED SERVICES INFORMATION message
is periodically transmitted by the network to inform UEs about a
change applicable for one or more MBMS services available in the
current cell and possibly in neighboring cells. The CONTINUE MCCH
READING information element (IE) is an MCCH in-band (included in a
message) notification. The IE indicates whether or not the UE
should continue reading MCCH in the next modification period.
[0116] During the modification period B, control information
regarding the service A is transmitted (step 3). In one aspect of
the invention, the above steps 1, 2 and 3 may be repeated for the
modification periods B and C, as shown in FIG. 12, and subsequent
modification period pairs.
[0117] As such, a UE which formerly during the modification period
A only read the MCCH would not have received the information on the
service A because the indication would only have been transmitted
on the MICH. However, in accordance with the present invention, the
UE is allowed to receive the necessary notification for the service
A information because the indication is now transmitted on both the
MICH and the MCCH during a modification period previous to the
modification period for which the service A information is
transmitted on. A UE which reads the MCCH will thus not need to
read the MICH.
[0118] Although the present invention is described in the context
of mobile communication, the present invention may also be used in
any wireless communication systems using mobile devices, such as
PDAs and laptop computers equipped with wireless communication
capabilities. Moreover, the use of certain terms to describe the
present invention should not limit the scope of the present
invention to a certain type of wireless communication system. The
present invention is also applicable to other wireless
communication systems using different air interfaces and/or
physical layers, for example, TDMA, CDMA, FDMA, WCDMA, etc.
[0119] The preferred embodiments may be implemented as a method,
apparatus or article of manufacture using standard programming
and/or engineering techniques to produce software, firmware,
hardware, or any combination thereof. The term "article of
manufacture" as used herein refers to code or logic implemented in
hardware logic (e.g., an integrated circuit chip, Field
Programmable Gate Array (FPGA), Application Specific Integrated
Circuit (ASIC), etc.) or a computer readable medium (e.g., magnetic
storage medium (e.g., hard disk drives, floppy disks, tape, etc.),
optical storage (CD-ROMs, optical disks, etc.), volatile and
non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs,
DRAMs, SRAMs, firmware, programmable logic, etc.).
[0120] Code in the computer readable medium is accessed and
executed by a processor. The code in which preferred embodiments
are implemented may further be accessible through a transmission
media or from a file server over a network. In such cases, the
article of manufacture in which the code is implemented may
comprise a transmission media, such as a network transmission line,
wireless transmission media, signals propagating through space,
radio waves, infrared signals, etc. Of course, those skilled in the
art will recognize that many modifications may be made to this
configuration without departing from the scope of the present
invention, and that the article of manufacture may comprise any
information bearing medium known in the art.
[0121] 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.
* * * * *