HK1147880A - Method of a base station and user equipment for use in wireless communications - Google Patents

Description

Method used in wireless communication, base station and user equipment

The present application is a divisional application of the chinese patent application entitled "point-to-multipoint service using shared channel in wireless communication system" with an application date of 30/4/2003 and an application number of 03809805.9.

Technical Field

The present invention relates generally to wireless communication systems, and more particularly to point-to-multipoint services in such systems.

Background

There is an increasing desire to use point-to-multipoint services in wireless communication systems, such as point-to-multipoint (PtM), shown in fig. 1, from one point (e.g., base station 10) to multiple points (e.g., multiple user equipment 12)₁-12₃) And sending the service. Examples of point-to-multipoint services are multimedia broadcast and multicast services.

In the system proposed by the third generation partnership project (3GPP), a channel that can be used for this service, the Forward Access Channel (FACH), is proposed. The FACH is a downlink common transport channel (TrCH) that can be received by all users. The FACH TrCH is propagated by applying it to a secondary common control physical channel (S-CCPCH). The S-CCPCH is transmitted to all cell users.

To limit the radio resources used by the S-CCPCH, the S-CCPCH data rate is limited. For illustrative purposes, if high data rate services are transmitted on the S-CCPCH, then low data redundancy needs to be used for transmission to achieve the high data rate. Since the S-CCPCH is transmitted to the entire cell, it is transmitted using a power level sufficient for a user to receive at a particular quality of service (QOS) at the cell edge. Propagating high data rate services at this power level may increase interference to other users, reduce system capacity, and result in inefficient use of cell resources, which is highly undesirable.

Moreover, due to the propagation nature of the S-CCPCH and FACH, the radio resources required for the S-CCPCH and FACH are very static, since channel allocation and messaging on these channels is provided at relatively low rates through layer 3 signaling techniques, and the Modulation and Coding Set (MCS) and transmit power level used by the S-CCPCH needs to be sufficient to maintain a particular QOS at the cell edge. The static nature of the S-CCPCH structure does not allow for dynamic adjustment of these parameters for efficient utilization of radio resources. In addition, scheduling of transmissions is also done at this slow rate, which does not allow for efficient utilization of this radio resource and does not allow for efficient multiplexing of the data streams to each user.

Another channel that may be used for point-to-point (PtP) services is the Downlink Shared Channel (DSCH). The DSCH is shared by multiple users, and transmissions to different users (user equipments) on the DSCH are separated by time. As a result, the DSCH is a time-shared channel.

Each user using the DSCH has uplink and downlink dedicated control channels. These control channels allow for more efficient radio resource utilization of the DSCH, which allows for power control of each user's transmissions on the DSCH and also allows for beamforming to better separate user transmissions. The use of power control and beamforming by the DSCH enables better utilization of resources compared to the FACH channel.

To receive data on the DSCH, a user first monitors its dedicated downlink control channel, and a burst on the downlink control channel may have a first portion and a second portion of a Transport Format Combination Indicator (TFCI). The first part indicates the transport format of the downlink dedicated channel and the second part indicates the presence and transport format of a subsequent DSCH transmission. The downlink control channel has a second part of the TFCI set if DSCH transmissions to a user are to be transmitted to the user. After a certain period of time, the transmission will occur in a subsequent Transmission Time Interval (TTI). The user may then monitor its transmissions on the DSCH. To verify that the user is the correct recipient of the DSCH transmission, it checks the user identifier in the transmission. If transmission is not to be transmitted, the second part of the TFCI will not be present in the downlink dedicated control channel.

Although the DSCH allows for a more efficient use of radio resources, only point-to-point services can be handled. To handle multiple reception points, multiple transmissions must be made on the DSCH. Therefore, transmission to many users requires many transmissions on the DSCH, which uses a large amount of radio resources.

It is therefore desirable to provide greater flexibility in wireless point-to-multipoint services.

Disclosure of Invention

Service data is transmitted in a wireless communication system and indicators are transmitted synchronously in the system for reception by a group of users in a cell that does not include all users in the cell. Each of the group of users receives the service indicator, each of the group of users monitors a service identification transmitted on the downlink shared channel, and the service data is transmitted on the downlink shared channel together with the service identification. Each of the users in each group detects a service identity and receives service data of a downlink shared channel.

According to one aspect of the invention, there is provided a method for use in wireless communications, the method comprising: synchronously transmitting a unique point-to-multipoint transmission indicator on a control channel to at least one of a plurality of user groups, each of the plurality of user groups not including all users, wherein the point-to-multipoint transmission indicator indicates a downlink shared channel on which a respective point-to-multipoint transmission is to be sent to at least one of the plurality of user groups; and transmitting the point-to-multipoint transmission with a point-to-multipoint identification to at least one of the plurality of user groups on the indicated downlink shared channel.

According to one aspect of the present invention, there is provided a base station for use in a wireless communication network, the base station comprising: a transmitter configured to synchronously transmit a unique point-to-multipoint transmission indicator on a control channel to at least one of a plurality of user groups in a cell, each of the plurality of user groups not including all users, wherein a service transmission indicator indicates a downlink shared channel on which a respective point-to-multipoint transmission is to be sent to at least one of the plurality of user groups; and the transmitter is configured to transmit the point-to-multipoint transmission with a point-to-multipoint identification to at least one of the plurality of user groups on the indicated downlink shared channel.

According to an aspect of the present invention, there is provided a user equipment for use in a wireless communication network, the user equipment comprising: a receiver configured to receive a unique point-to-multipoint transmission indicator, wherein the unique point-to-multipoint transmission indicator is synchronously transmitted on a control channel to at least one of a plurality of user groups in a cell, each of the plurality of user groups excluding all users, wherein the point-to-multipoint transmission indicator indicates a downlink shared channel on which a corresponding point-to-multipoint transmission is to be transmitted to at least one of the plurality of user groups; and the receiver is configured to receive the point-to-multipoint transmission, wherein the point-to-multipoint transmission is transmitted to at least one of the plurality of user groups on the indicated downlink shared channel with a point-to-multipoint identification.

Drawings

Fig. 1 is an illustration of a point-to-multipoint service;

FIG. 2 is an illustration of a preferred shared channel;

figure 3 is a simplified schematic diagram of a preferred radio network controller/node B and user equipment;

figure 4 is a simplified schematic diagram of a preferred radio network controller having a scheduling mechanism for a preferred shared channel;

FIGS. 5A, 5B, 5C, 5D and 5E are illustrations of preferred signal scheduling for the common channel;

fig. 6 is an illustration of preferred signals for establishing and transmitting a point-to-multipoint service on a downlink shared channel; and

fig. 7 is a simplified schematic diagram of a preferred node B and user equipment using transmit power control and beam steering for a shared channel.

Detailed Description

Although the preferred embodiments are described in connection with the preferred 3GPP proposed system, they may be used with other radio systems using point-to-multipoint transmission.

FIG. 2 shows a preferred shared channel 16 and its associated downlink and uplink dedicated control channels 14₁-14_NAnd (4) description. Although the preferred embodiment uses downlink and uplink dedicated control channels, in alternative embodiments, the data transmitted on these channels may be transmitted via other means, such as a common physical control channel or layer 2/3 signal. A set of user UEs 112₁、...、UE J12_J、...、UE N 12_NTo receive the shared service 16. Downlink dedicated control channel 14 for each user₁-14_NIs used to establish a shared channelAnd other purposes. Shared channel 16 is sent by base station 10 and by UE 12₁-12_NAnd receiving the group. UE, e.g. UE X12_xNot in their dedicated control channels 14_xWhich receives the shared channel assignment display and does not receive data for the shared channel 16.

FIG. 3 shows RNC 20/node B18 and one of the UEs (UE)_J12_J) For use in transmitting data over the shared channel. At the RNC 20/node B18, each Downlink Dedicated Control Channel (DDCC) generator 24₁-24_NFor each UE 12₁-12_NA control channel signal is generated. A multipoint synchronization device 25 is used to synchronize DSCH allocations with a group of users subscribed to a common PtM service over the users' DDCCs. For UE J12_JAfter its dedicated control channel has been emitted by the antenna 32 or antenna array via the wireless radio interface 22, this signal is transmitted by the UE J12_JIs received by the antenna 34 or antenna array and processed by the control channel receiver 36 to recover the control data for that channel.

A downlink shared channel generator 26 generates the shared channel signal for transmission over the wireless interface 22. The shared channel signal is transmitted by the UE J12 using its antenna 34 or antenna array_JAnd receiving. The common channel data is recovered by the downlink common channel receiver 38 using the dedicated control channel data, and a common channel measurement device 40 collects channel quality measurements/information, such as received signal code power, relative interference and block error rate, for the downlink dedicated channel and/or the common channel. Measurements/information are sent to the RNC 20/node B18. Typically, this channel quality measurement/information is a Transmit Power Command (TPC), phase shift and amplitude information used in beamforming, and received power and interference measurements.

A measurement receiver 30 at the RNC 20/node B18 recovers the channel measurements from all users sharing the channel. A power control means 28 uses the channel measurements/information to set the power level of the shared channel. In addition, a transmit diversity device 29 may use phase shift and amplitude information to set the beamforming of the shared channel. The power level and beamforming are preferably updated in each Transmission Time Interval (TTI), although longer time ranges may be used.

The dedicated channel is continuously maintained and the received BLER is used to determine a signal-to-interference ratio (SIR) target. TPC commands are generated based on the received estimated SIR. When the DSCH is activated, the required power is obtained from the dedicated channel. However, they are usually not identical due to the difference in BLER requirements and physical configuration between the two. For PtM transmission, the transmission power level is set to achieve the user-desired QOS at the worst reception quality for the PtM transmission. Users within the PtM user group that cannot meet QoS requirements due to physical limitations of transmission may also be omitted.

For services having multiple sub-streams, the transmission characteristics of the various sub-streams may be handled individually. For illustrative purposes, a multimedia service may have audio, video, and text sub-streams. The QOS of each sub-stream may be different such that each sub-stream may use different transport attributes. The method enables better resource efficiency to be achieved, and each sub-stream can be processed separately on individual DSCH transmission, rather than transmitting each sub-stream to meet the highest QOS sub-stream requirements.

Fig. 4 is a simplified block diagram of a preferred Radio Network Controller (RNC) 42. The preferred RNC 42 has a scheduling mechanism 46, which scheduling mechanism 46 is preferably used to schedule data every TTI, although longer scheduling times may be used. The scheduling mechanism 46 receives data to be transmitted on the shared channel resource. The received data includes data for PtP and PtM services. The scheduling mechanism schedules transmitted data in PtP and PtM transmissions. To schedule this information, the scheduling mechanism 46 takes into account the QOS required for each transmission (including its required data delay and flow), and the physical transmission requirements (including the total power requirements of the entire cell and each channel and beam steering information). For each TTI, the scheduling mechanismThe best use of cell resources is made when it decides to schedule the data transmission. For illustrative purposes, the total cell power requirement can be nearly achieved at a particular TTI. If the PtM service can be delayed, the PtM service transmission can be delayed by one or two TTIs until the total cell power requirement decreases. If such flexibility in scheduling according to TTIs is not available, resource decisions are made and do not change during a particular time period (e.g., 100 milliseconds or 1 second). In these cases, resources are allocated and do not change during the time period. As a result, some transmissions that could have been transmitted are not transmitted due to the stalled allocated resources. RNC 42 signals UE 12₁-12_NThe channel and timing of PtP and PtM transmissions are signaled. TTI-based scheduling makes it more capable to meet the QOS and data delay requirements while still maintaining a high utilization of DSCH cell resources. The cell physical channel and PtP/PtM data transmission requirements change dynamically, so the scheduling mechanism 46, which can react quickly to these changes, is further more able to achieve the QOS requirements while at the same time making the most efficient use of the cell physical resources.

The scheduling mechanism 46 may also take into account physical transmission requirements. For example, one user or group of users may require a more robust MCS than another MCS. During the next TTI, resources may only be provided to the less robust MCS. The scheduling mechanism 46 may then schedule transmission of the PtP user or PtM user group to maximize utilization of the available resources. Because the available physical resources and channel quality measurements vary based on TTI, the ability to schedule within this interval increases the number of satisfied users and improves the overall utilization and efficient use of physical resources, as data is available for transmission with specific QOS requirements.

The preferred scheduling per TTI can reduce resource conflicts between services by reducing the occurrence of idle radio resources. Furthermore, the TTI scheduling granularity (granularity) allows for transition from PtM transmission to PtP transmission and vice versa during operation. For illustrative purposes, multimedia services are delivered to multiple users via PtM transmission. For a particular TTI, only one user needs this transmission and the scheduling mechanism 46 schedules the TTI service transmission as PtP. In the next TTI, multiple users need the service transmission and a PtM transmission is scheduled. Using the preferred scheduling mechanism 46, the PtP and PtM services can be segmented and reassembled over multiple non-contiguous TTI allocations. This scheduling mechanism 46 further increases the flexibility of radio resource assignment and results in greater radio resource efficiency.

Fig. 5A, 5B, 5C, 5D, and 5E are illustrations of possible allocations of shared channels for PtM services. The dedicated control channel 14 for each user (user 1 through user N) in the PtM user group receiving service as shown in FIG. 5A₁-14_NThe control information is transmitted. As shown in fig. 5B of the 3GPP FDD system, there is a chip offset "DOFF" used to stagger (trigger) the start of the user TTI. As shown in fig. 5A and 5B, for each user in the PtM service user group, a Service Transmission Indicator (STI)50 is transmitted along with dedicated control information. The service delivery indicator 50 indicates that service data is to be transmitted over the shared channel 16. The preferred service transmission indicator indicates the presence of the second part of the TFCI in the dedicated downlink control channel burst, although a different indicator (e.g., bits or characters) may be used. After a set period of time, the service data is transmitted over the shared channel 16. The transmitted service data preferably has an ID 52 associated with the service. The service id (sid)52 is used to verify that the correct group of recipients are receiving the transmission.

Fig. 5C illustrates the distribution of multiple PtM services. Users 1 and 2 are in group a and receive a PtM service. Users 2 and 3 are in group B and receive another PtM service. A particular user may receive multiple PtM and PtP services. As shown in fig. 5C, user 2 receives both PtM services. DDCC 14 at each subscriber₁To 14₃In (1), service indicator 50₁、50₂Is transmitted to indicate that the corresponding service transmission is transmitted on its DSCH. May be on the same DSCH or multiple DSCH 16₁、16₂And uploading the plurality of services. Each service transmission has a service ID 52₁And 52₂. In FIG. 5D, the STI 50₁And 50₂And DDCC are staggered in time. However, on different shared channels 16₁、16₂May be performed simultaneously.

Fig. 5E shows different signaling methods, where multiple user groups 1-G can receive services. Each subscriber has a DDCC 14₁₁To 14_GNAnd receives STI to indicate the PtM transmission. UE groups 1-G will receive the service. The data transmitted in the shared channel includes a Group ID (GID)54 for each receiving group₁-54_G。

Fig. 6 is an illustration of preferred signals for establishing and transmitting a point-to-multipoint service on a DSCH. The UMTS Terrestrial Radio Access Network (UTRAN)70 signals each user, user equipment 12, to receive service of the transmission attributes of the transmission (74). Data transmitted for the point-to-multipoint service is received by the UTRAN 70 from the core network. Each user of the PtM service may not be able to be activated/configured to receive the service at the same time. A user may register for the service at any time, even when the service is in progress or the user may be entering a particular PtM service area. Each user configures itself to receive transmissions (72) and monitors the dedicated control channel (82) assigned by the DSCH.

Each user maintains the uplink and downlink dedicated channels and transmits channel information (e.g., received interference, received power, calculated pathloss, and location information) to the UTRAN 70 (76). The received interference and path loss may also be indicated by the use of TPC and the position information may be signaled by a phase shift indication. Using the channel information for all users of each PtM user group, the RAN70 establishes allocation criteria for the DSCH transmissions, such as transmission power levels and beamforming requirements (78). For illustrative purposes, the RAN70 will typically set the transmission power level to the level received by the user with the worst reception quality (e.g., the user with the largest path loss) if beamforming is not used. If beamforming is used, the power level of each beam is based on the user within the beam with the worst quality. For beamforming, the location data is used to group users based on their location to establish the number, size, and shape of beams needed to serve the group. In order to optimise the use of radio resources, these parameters are preferably updated every Time Transmission Interval (TTI), preferably at each user's uplink dedicated control channel, although longer periods of time may be used between updates by transferring equivalent data using layer 3 signalling procedures.

The UTRAN 70 transmits a service indicator to the user group on the dedicated control channel of each user in a synchronized manner (80). Each user in the group configures itself to receive the PtM transmission (82).

Since the indication of the shared channel transmission is usually not fully error-tolerant, it is preferred that the identifier is transmitted in the DSCH. However, in alternative embodiments, the DSCH identifier may not be used. For PtP services, a specific user identifier is signaled in DSCH transmissions. For the preferred embodiment, a PtM service identifier common to all users within a PtM user group is signaled in the DSCH (84). Each user identification PtP user specific identifier or PtM service identifier is sent in the service transmission. The received service data is forwarded to the UE 12₁-12_NA common communication channel (86).

Fig. 7 is a diagram of a node B18 and a UE 12 for beam steering using adaptive power control and DSCH_JFor a simplified illustration. The UE 12_JThe DSCH is received over the radio interface 64 using an antenna 72. The DSCH data is recovered by a user DSCH receiver 66. The user feedback transmitter 68 transmits channel information (e.g., TPC and/or phase shift information) back to the node B18. The node B18 recovers the channel information from all users associated with each PtM user group using a user feedback receiver 62.

The data for each PtM user group that is to be transmitted over the DSCH is generated by a DSCH generator 56. A power control means 58 uses the received feedback information to establish the transmission power level of the or each DSCH bundle. The DSCH beam is composed of beamThe steering controller 60 decides which antenna 70 to direct to the node B's antenna array₁To 70_NEach providing an appropriate magnitude (magnitude) and weight value.

Claims (14)

1. A method for use in wireless communications, the method comprising:

synchronously transmitting a unique point-to-multipoint transmission indicator on a control channel to at least one of a plurality of user groups, each of the plurality of user groups not including all users, wherein the point-to-multipoint transmission indicator indicates a downlink shared channel on which a respective point-to-multipoint transmission is to be sent to at least one of the plurality of user groups; and

transmitting the point-to-multipoint transmission with a point-to-multipoint identification to at least one of the plurality of user groups on the indicated downlink shared channel.

2. The method of claim 1, wherein each user is associated with a unique downlink control channel on which the point-to-multipoint indication is transmitted.

3. The method of claim 1, wherein each of the plurality of user groups is associated with a unique uplink control channel.

4. The method of claim 1, wherein each user is configured to detect the point-to-multipoint identification and receive the point-to-multipoint transmission on the downlink shared channel.

5. The method of claim 1, further comprising receiving channel information.

6. The method of claim 5, wherein a service data transmission is determined from the channel information.

7. A base station for use in a wireless communication network, the base station comprising:

a transmitter configured to synchronously transmit a unique point-to-multipoint transmission indicator on a control channel to at least one of a plurality of user groups in a cell, each of the plurality of user groups not including all users, wherein a service transmission indicator indicates a downlink shared channel on which a respective point-to-multipoint transmission is to be sent to at least one of the plurality of user groups; and

the transmitter is configured to transmit the point-to-multipoint transmission with a point-to-multipoint identification to at least one of the plurality of user groups on the indicated downlink shared channel.

8. The base station of claim 7, wherein the transmitter is further configured to transmit the point-to-multipoint indication to each user via a unique downlink control channel.

9. The base station of claim 7, wherein each of the plurality of user groups is associated with a unique uplink control channel.

10. The base station of claim 7, further comprising a receiver configured to receive channel information.

11. The base station of claim 10, wherein the transmitter transmits service data based on the channel information.

12. A user equipment for use in a wireless communication network, the user equipment comprising:

a receiver configured to receive a unique point-to-multipoint transmission indicator, wherein the unique point-to-multipoint transmission indicator is synchronously transmitted on a control channel to at least one of a plurality of user groups in a cell, each of the plurality of user groups excluding all users, wherein the point-to-multipoint transmission indicator indicates a downlink shared channel on which a corresponding point-to-multipoint transmission is to be transmitted to at least one of the plurality of user groups; and

the receiver is configured to receive the point-to-multipoint transmission, wherein the point-to-multipoint transmission is transmitted to at least one of the plurality of user groups on an indicated downlink shared channel with a point-to-multipoint identification.

13. The user equipment of claim 12, wherein each of the plurality of user groups is associated with a unique uplink control channel.

14. The user equipment of claim 12, wherein the user equipment further comprises a transmitter configured to transmit channel information.