Method and system for organizing the cells of a wireless communication system and allocating resources to provide multimedia broadcast services

Method and system for organizing wireless communication system cells and allocating resources to provide multimedia broadcast services

The present invention relates broadly to a type of wireless communication. More particularly, the present invention is directed to a wireless communication system (such as Time Division Duplex (TDD), Frequency Division Duplex (FDD), Code Division Multiple Access (CDMA) and/or Global Mobile Telecommunications System (UMTS) ) Provides at least one or more multimedia broadcasting services (MBMS).

The third-generation cooperative partner project (3GPP) broadband CDMA (W-CDMA) system was outlined in the UMTS standard release (Release) R99/R4 and R5 operation plan. This system uses TDD and FDD modes, and uses multiple common and dedicated channels to establish a communication link. The downlink (DL) common channels include at least one primary common control entity channel (P-CCPCH) including the BCH (broadcast channel) and/or at least one secondary common control entity including a forward access channel (FACH) Channel (S-CCPCH).

The communication link is typically established using a wireless transmission/reception unit (WTRU). The WTRU includes (but is not limited to) a user device, a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device that can operate in a wireless environment. These typical wireless environment types include (but not limited to) wireless local area networks and public ground mobile networks. The WTRU described herein can operate in a time division mode or a frequency division mode (such as TDD and FDD, respectively). "Base station" includes (but is not limited to) Node B, site controller, access location, or other interface devices in a wireless environment.

It is well known that the connection performance at the cell edge of a multi-cell wireless communication system has long been a concern, especially for common channels. Link analysis has shown that the wireless WTRU on the edge of the cell will have a block error rate (BLER) greater than 10% or even higher under a certain fading state. In addition, in order to optimize the capacity, it is desirable to set an S-CCPCH in the same slot as the P-CCPCH.

A special level of service provided by network operators and delivered by S-CCPCH is MBMS. In wireless communication systems, MBMS is used to efficiently distribute common data services to multiple users.

MBMS is different from traditional point-to-point (PtP) services (such as voice or two-way video conferencing) in that a group of users wants to receive the same information transmitted by the network. Therefore, the implementation of MBMS is different from the PtP service. The latter is usually transmitted on a user-specific physical channel, but the former is more suitable for transmission on a common physical channel that can be received by multiple WTRUs. In terms of data rate, the demand for MBMS varies within the range of about 100 kbps, but for the demand for MBMS, the most general demand is shown at about 64 kbps per cell, and there are 90 in this cell. % Of users are covered by MBMS.

The basic problem of providing MBMS in a CDMA system is that unless a dedicated channel is used, it is difficult to make the physical channel carrying MBMS receive power control. Therefore, it is necessary to set the transmission power of the base station so that the MBMS user located farthest from the base station in the serviced group can receive the physical channel quite reliably. Essentially, the base station must support the possibility that some users in the N MBMS user groups are at the edge of the cell. Therefore, the transmission power can be set according to the needs of the users. However, for most users, this power is far too much. This will cause asymmetric interference to other users in the same and neighboring cells.

As an example, preliminary research on broadband W-CDMA FDD shows that in order to achieve more than 90% WTRU coverage in a typical FDD cell with 64 kbit/s MBMS, typically about 30% will be required. % Of the base station's power is used to transmit MBMS on the physical channel. It should also be noted that it is extremely difficult to serve MBMS users at the edge of the cell at a sustainable data rate.

Therefore, what is required is to reduce this large resource demand. For this purpose, some methods have been discussed that can be used to reduce the power ratio required by MBMS to improve the link performance of the MBMS channel. These include: 1) longer interleaving, that is, longer transmission time interval (TTI) with better time diversity; 2) transmit diversity for the MBMS channel; and 3) improve channel coding. This technique can be used to reduce the FDD base station power ratio required to support the 64 kbit/s MBMS instance from 30% to about 10-20%.

For UMTS narrowband TDD (NTDD) (1.28Mcps option), the high level of interference generated by the MBMS can be mitigated by developing frequency reuse in the physical channel time slot (TS). This is possible in principle because the bandwidth of each NTDD carrier is small. For example, three narrowband carriers can be supported within the 5MHz range allocation of FDD or Wideband TDD (WTDD).

Using this method, certain cells will transmit MBMS in a special time slot (TSn) with frequency fl, the second group in TSn but at frequency f2, and the third group in TSn but at frequency f3. . Because the distance between two base stations that transmit MBMS at the same frequency in the same TS is longer, more space separation can be achieved, and therefore, less interference from MBMS TS can be generated to other cells. However, the operator must have these three available frequencies in the expansion area. Techniques to reduce transmission (Tx) power requirements include, for example, using a longer TTI length, soft handover, and Tx diversity.

As a result of the previous discussion on the Global Terrestrial Radio Access (UTRA) FDD, it has been indicated that the support of 64 kbit/s on S-CCPCH can be reduced to some 15-20% of the base station DL Tx with reference to MBMS. power.

The previous system reveals an R4-based LCR TDD system that is implemented in an expanded area containing 3 low chip rate (LCR) carriers in a 5MHz bandwidth. In this system, MBMS is mapped to One is included on the S-CCPCH in a single time slot, and a frequency reuse factor of 3 is assumed for this time slot. These results show that LCR TDD can provide up to 64kbps MBMS under the block error rate = 10% (BLER = 10%); or when the full base station Tx power is used in the S-CCPCH slot, it can support the BLER =About 16-32kbps under 1%.

Furthermore, in the aforementioned communication system technology using the time-domain reuse factor of 3, the cells in the first group will transmit their MBMS in TSn, and the cells in the second group will be in TS<u style="single">n+1</u>The MBMS and the cells in group 3 will be sent in TS<u style="single">n+2</u>Transmit its MBMS. The cells in the first group will not be TS<u style="single">n+1</u>And TS<u style="single">n+2</u>Used for any transmission (both uplink (UL) and DL); the cells in the second group do not use TS<u style="single">n</u>And TS<u style="single">n+2</u>Used in any transmission and so on. This method operates in a manner independent of the duration of the MBMS data block (ie, independent of its TTI). The average MBMS data rate generated by this method for each cell is 170kbps/cell, and the time slot efficiency on MBMS TSs in this system is 170kbps/3TSs=56kbps/TS.

Figure 1 shows a typical data frame sequence used by the aforementioned communication system technology, whereby a data frame is divided into TS1-15. These frames are repeated, and the same TS assignment is maintained for subsequent frames until the TS is cleared or specially reassigned. Each time slot can potentially be assigned a predetermined number of frames.

Figure 2 shows the channel assignment diagram used by the aforementioned communication system technology. Assign cells in different groups to different time slots. This arrangement can be used when MBMS broadcasts are transmitted from a plurality of sources that can have overlapping coverage areas.

To clarify, assign a code that matches the cell in the first group (group 1) to the TS<u style="single">1</u>WTRU M1 in the. Assign a code that matches the cell in the second group (group 2) to the TS<u style="single">2</u>WTRU M2 in the WTRU, and assign a code that matches the cell in the third group (group 3) to the TS<u style="single">3</u>WTRU M3 in the. This appears in frame A, and the subsequent frames are repeated until one or more assignments are changed.

Still referring to Figure 2, in frame A78, the cells of this group 1 are assigned to the first time slot group TS<u style="single">1</u>. Remaining time slot TS<u style="single">2</u>-TS<u style="single">n</u>It is not used by group 1. The physical channel used by group 1 is assigned to the entire S-CCPCH. Assign the cells of these groups 2 to the second time slot group TS<u style="single">2</u>. Remaining time slot TS<u style="single">1</u>And TS<u style="single">3</u>-TS<u style="single">n</u>It is not used by group 2. The physical channel used by group 2 is assigned to the entire S-CCPCH. Assign the cells of these groups 3 to the third time slot group TS<u style="single">3</u>. Remaining time slot TS<u style="single">1</u>-TS<u style="single">2</u>And TS<u style="single">4</u>-TS<u style="single">n</u>It is not used by group 3. The physical channel used in Group 3 is assigned to the entire S-CCPCH. Repeat this pattern for frame B 80, and set the corresponding time slot TS<u style="single">1</u>-TS<u style="single">3</u>Assigned to these cells in different groups.

It should be noted that the shortcoming of the communication system technology mentioned above is the time slot TS<u style="single">1</u>, TS<u style="single">2</u>And TS<u style="single">3</u>Cannot be used for other transmissions. Therefore, if a time slot is used for a group of cells, the time slot cannot be used by another group of cells. It would be desirable to have a set of TDD cells that can share a time domain reuse pattern.

For suitable radio resource applications, the Global Terrestrial Radio Access Network (UTRAN) can track the number of effective MBMS users. In each cell, for each MBMS, the effective number of users can be used to determine the type of transmission and physical resources that can be applied to the MBMS in each cell, and when to start and stop the MBMS. MBMS.

Service is established due to MBMS activation and user migration. The mechanism that has been conceived to track MBMS users is incorporated into the Radio Resource Control (RRC) layer 3 to signal the "join" (service activation) of MBMS and cell update to maintain the location of these users. With these tools, it is possible to know which user has activated the service and the service needs to be distributed to that cell.

Due to the application of closed loop power control and transmission diversity, when the number of users of a particular type of MBMS is small, the dedicated channel is more efficient. When the number of users increases, the dedicated channel efficiency gain cannot compensate for the duplication of each data stream, so a common channel that can provide a single data stream to multiple users is used. This method is known as transmission/physical channel switching and can be applied at any time during MBMS transmission.

When using a common channel, it is not practical to apply ARQ technology to ensure successful delivery. Therefore, each MBMS transmission can be repeated to increase the probability of successful delivery. The number of retransmissions will take into account the estimated BLER applied to the service delivery and physical resources.

MBMS will be transmitted several times to better ensure successful delivery. The number of retransmissions is related to the expected channel quality. This number will take into account the worst-case scenario to achieve a predicted quality of service (QoS). One of this example is when the user is at the edge of the cell and the result is a high BLER. Users will often experience better radio propagation conditions and will achieve a successful delivery well before the retransmission is complete.

All in all, some improvements are desired to overcome the shortcomings associated with the conventional MBMS. First, a new method that can support UMTS WTDD and NTDD is needed, which can also increase the capacity of the common channel used to provide MBMS. Secondly, we want a system that can use performance improvement techniques to improve resource efficiency, whereby a set of TDD cells can be installed to share a time-domain reuse pattern. Third, there are no obvious signs of service delivery, so any user who has activated MBMS will be charged for receiving it. Therefore, for UTRAN, what is desired is to provide a sufficient number of retransmissions to ensure reliable reception.

The present invention can be implemented in a wireless multi-cell communication system that includes at least one network that communicates with one or more WTRUs. The communication system can control the distribution of MBMS from the network to the WTRU.

In a specific embodiment, the dissemination of MBMS can be performed by the following methods: organizing the cells of the communication system into plural groups containing one or more cells, and assigning resource units to each cell in the communication system. A cell group, and the assigned resource units are allocated in each cell of the communication system for MBMS transmission. The WTRUs receive information indicating how to access the resource units allocated for MBMS transmission, and the WTRUs can receive MBMS from one or more cells of the communication system.

Before executing the procedures described above, MBMS requirements can be established for the communication system, and resource units that can be used for each cell available for MBMS in the communication system can be determined. When there is a change in the MBMS demand or the MBMS demand cannot be met, the procedure can be repeated.

The communication system can be an FDD communication system, whereby multi-frame distribution can be used. A repeat cycle can be established for all cells in the communication system. Furthermore, a frame subgroup to be used for MBMS transmission can be created for each cell group in each repetition period.

The communication system can be a TDD communication system, whereby it can be determined whether multi-frame allocation can be used in the communication system. When it has been decided to use multi-frame allocation in the TDD communication system, a repetition period can be established for all cells in the communication system. Furthermore, a frame subgroup to be used for MBMS transmission can be created for each cell group in each repetition period. When it has been decided not to use multi-frame allocation, a different time-slot combination can be provided for each cell group, wherein the same time-slot combination is used in each frame.

The present invention can be understood in more detail from the preferred embodiments described below, which are illustrated by examples and can be understood by related accompanying figures.

The present invention will be described with reference to figures, where similar numbers represent similar elements. Although the present invention has been described in the related TDD and FDD type wireless communication systems, it is important to note that the present invention can be implemented in any type of wireless communication system, including TD-SCDMA and CDMA 2000.

Figure 3 is a flow chart of a specific embodiment according to the present invention, which shows that the program 300 is executed to spread MBMS from a wireless multi-cell TDD or FDD communication system network (for example, UTRAN) to one or Steps for multiple WTRUs. In step 305, it is determined what kind of MBMS needs to be established for the communication system. These MBMS requirements can define channel allocation parameter specifications, such as data rate, target BLER, TTI, and/or minimum number of users or the like.

In step 310, the resource unit required by each cell in the communication system can be determined according to its availability to be allocated to the MBMS. For a TDD communication system, the resource unit may include some physical channels defined by a specific carrier frequency, scrambling code, a selectable channelization code, and a frame group. As specified in TS25.221, the physical channel in TDD is a kind of burst, which can be transmitted in a special time slot within the allocated radio frame. The allocation can be continuous (that is, the time slots in each frame are allocated to the physical channel), or the allocation can be continuous (that is, only the time slots in the subgroup of all frames are allocated). ). For FDD communication systems, the resource units may include physical channels defined by a specific carrier frequency, scrambling code, an optional channelization code, and a start and end time for providing a duration. In step 315, the cells are organized into plural groups (ie, groups) containing one or more cells to ensure a certain degree of MBMS. In step 320, the resource units are assigned to each cell group in the communication system.

In step 325, if the FDD communication system is used to perform the procedure 300, then in step 335, multi-frame allocation is used. If the TDD communication system is selected to perform the procedure 300, it is determined in step 330 whether to use multi-frame allocation. The use of multi-frame allocation can be based on the spatial separation (ie, distance) between the cells. When multi-frame allocation is used in the FDD communication system (step 335) or in the TDD communication system (as indicated by the "Agree" output of step 330), the interference in the communication system can be minimized, so that A repetition period is established for all cells and a frame subgroup to be used for MBMS transmission is established in each repetition period for each cell group to ensure a certain MBMS service level (step 340). If it has been decided not to use multi-frame allocation in the TDD communication system, a different TS combination is provided for each cell group, and the same TS combination is used in each frame (step 345). It should be understood that the decision in step 330 can be performed independently of each other or in relation to any of the previous steps 305, 310, 315, and 320.

In step 350, the assigned resource unit is allocated to each cell of the communication system for MBMS transmission. In step 355, the WTRUs may receive information to indicate how to access the resource units allocated for MBMS transmission. In step 360, the WTRUs may receive MBMS from one or more cells. In step 365, it is determined whether the MBMS requirements determined in step 305 have not changed or are still satisfied. If the MBMS requirements have not changed and are still met, the procedure 300 will return to step 360 where the WTRU continues to receive MBMS. If these MBMS requirements have been changed or are not satisfied, the procedure 300 will return to step 305 at the beginning of the procedure 300, so that a new MBMS requirement can be established.

According to the present invention, time slot management is used to reduce interference between cells, thereby assigning time slots to special frames and assigning frames to cells in an excellent manner. This time slot management allows maintaining the most ideal power for each cell group in a cell group. For TDD, this time slot management can ensure that the WTRU receiving DL signals can experience minimal interference from other cells in these time slots. They can successfully decode the DL data received on these channels, minimize the need for retransmission, and ensure that high data rates are covered on these channels in the cell area. This can be achieved by assigning channels to the WTRU by assigning time slots to divide the cell groups into groups and each cell group has a unique time slot assignment group.

The present invention can implement a time-domain reuse pattern on a wireless communication system with multiple cells to support MBMS services. The time domain reuse and frequency reuse have the same impact on improving the reception quality. According to the present invention, the time-domain reuse pattern can guarantee that certain cells in the TDD expansion area will transmit their MBMS service in certain time slots, which will remain and not be used by other cells.

The TDD viewpoint of the present invention can be applied to the conventional example of S-CCPCH or DL shared channel in UMTS TDD R99 (3.84Mcps and 1.28Mcps selection) and later, which is related to the specific content delivered by it (such as MBMS) It is irrelevant, but the trustworthy service of MBMS is regarded as a very important special instance. Even without MBMS, the technology of the present invention will improve the data rate and achievable coverage at the edge of the cell. In order not to lose universality, consider the example of MBMS transported on S-CCPCH; even if the feasibility of this method can be extended to any type of service transported on any DL common channel (such as DL shared channel). R5 uses another type of DL common channel (ie, HS-DSCH) for both FDD and TDD.

The impact of the channel assignment technology implementing the present invention can be illustrated by the results from the WTDD simulation. In the DL, each WTRU's data rate close to 2Mbps can be achieved by filling its data with a 16 spreading code with SF=16 in each of the 12 DL time slots. If each frame is continuously transmitted, a single time slot using all 16 SF=16 spreading codes can therefore generate a data rate of about 170kbps. In all the following examples, it can be simply assumed that one full time slot for each frame is assigned to the S-CCPCH or equivalently to the MBMS. Similarly, assume that each slot is 170kbps.

According to the present invention, the time slots are assigned in a manner that can reduce interference (which occurs in overlapping coverage areas when broadcasting MBMS broadcasts and other broadcasts). The time slot can be reused in these cells according to the needs of MBMS. This can be done in a manner independent of the duration of the MBMS data block and independent of the TTI.

According to the present invention, if the same TS is used by all cells, multiple frame allocation and TTI can be successfully developed and used. In each predetermined group of the cell group, the cells in each group are assigned to a unique S-CCPCH group.

According to the present invention, possible time-slot combinations can be reused according to its repetition period. This can create a time domain reuse pattern. If the same TS is to be used by all cells, multiple frame allocation and TTI can be successfully developed and used. With each MBMS data block TTI=20 milliseconds (2 frames), the S-CCPCH of each cell can be allocated with a repetition period of 80 milliseconds (8 frames).

The first cell group will send its MBMS in frames m and m+1 with a provided time slot n, and will not send anything in time slot n in frames m+2,...,m+7. The second cell group will transmit its MBMS in the same time slot n, but in frames m+2 and m+3, but in frames m, m+1 and m+4,..., m+7, it will not transmit anything in time slot n. The third cell group will transmit its MBMS in the same time slot n, but in frames m+4 and m+5, but in frames m,...,m+3 and m+6,...,m+7, it will not transmit anything in time slot n . Finally, the fourth cell group will transmit its MBMS in the same time slot n in frames m+6 and m+7, but there is nothing in frames m, ..., m+5.

The average MBMS data rate of each cell generated by this method is 170kbps/4=42kbps/cell, and the MBMS TSs efficiency in this system is 170kbps/1TS=170kbps/TS. The system will experience an effective time domain reuse factor of 4 and practically no interference on MBMS TSs. In Table 1 below, "n" represents "a cell of S-CCPCH carrying MBMS in this frame with time slot n." No "n" means that the cell does not convey anything in slot n at this time in this frame.

<tables><img file="TWI345424B_D0001.tif" /></tables>

This procedure can be deduced to other possible combinations, such as 1 MBMS TS, repetition period of 40 ms and TTI=10 ms; or 1 MBMS TS, repetition period of 160 ms and TTI=40 ms.

It should be noted that the time domain reuse factor of 3 is often used in the communication system technology described above, which can be a highly attractive option. Here, this concept can be achieved by using a repetition period of 60 milliseconds and TTI=20 milliseconds. From the point of view of the physical layer, this is a constant change. There is a few revisions to this higher-level protocol, which now only supports standardized repetition cycles of 10, 20, 40, 80, 160, 320, and 640 milliseconds. At this time, the domain reuse pattern will potentially generate an average MBMS data rate per cell of 170kbps/3=56kbps/cell. With this procedure, only an "empty" TS is needed to accommodate the MBMS.

According to the present invention, with the potential of 170/2=85kbps, a time domain reuse of 2 can be achieved. If the same single TS is used for MBMS by all cells, then with a 40 millisecond repetition period (but the TTI of each cell group is changed), multi-frame allocation and TTI can be successfully developed and used. In the following Table 2,'n' represents a cell group of S-CCPCH carrying MBMS in the time slot n of this frame. No'n' means that the cell group does not convey anything in slot n of this frame at this time.

<tables><img file="TWI345424B_D0002.tif" /></tables>

It should be noted that the cells in groups 1-4 allow TTI=20 milliseconds (when performing such multi-frame allocation, it can be achieved by using the "compensation" parameter). The cells in groups 5 and 6 do not support transmission in two consecutive slots. As a result, the cells in groups 5 and 6 were assigned to TSs separated by time. It can be seen that each cell group has at least one slot without interference between cells from any particular other group. Furthermore, three pairs of groups without inter-cell interference can be operated: (1) group 1 and group 2; (2) group 3 and group 4; and (3) group 5 and group 6.

Utilizing the redundancy in the front error correction (FEC), it can successfully operate over most of the range, while supporting up to 85kbps and requiring only one slot per frame.

Node B sync can be processed by assigning the usage rate of the time slot. In this method, synchronization bursts can be used to support node B synchronization. This method has been initially ruled out when using the aforementioned technical method, because the degree of interference will prevent reliable detection. However, with the present invention, it is now more feasible for one cell to hear the synchronous burst of neighboring cells during the slot when the cell is not transmitting.

Figure 4 is a diagram of channel assignment used in a TDD communication system, which uses multi-frame assignment according to the present invention. Figure 4 provides an example of using a combination of different TSs and frames assigned to cells to perform time-domain reuse. This modified technology can overlap assignments. Within each predetermined group of cell groups, the cells in each group are assigned to a unique S-CCPCH group. However, unlike in Figure 2, the present invention shows an overlap between the groups S-CCPCH.

As shown in Figure 4, the cells of group 1 are assigned to the first time slot group TS in each frame<u style="single">1</u>, TS<u style="single">2</u>. Remaining time slot TS<u style="single">3</u>-TS<u style="single">n</u>It is not used by group 1. The physical channel assignment of Group 1 is the entire S-CCPCH. The cells of group 2 are assigned to the second time slot group TS in each frame<u style="single">3</u>, TS<u style="single">4</u>. Remaining time slot TS<u style="single">1</u>-TS<u style="single">2</u>And TS<u style="single">5</u>-TS<u style="single">n</u>Not used by group 2. The physical channel assignment of Group 2 is the entire S-CCPCH. The cells of group 3 are assigned to the third time slot group TS in each frame<u style="single">2</u>And TS<u style="single">3</u>. Remaining time slot TS<u style="single">1</u>And TS<u style="single">4</u>-TS<u style="single">n</u>Not used by group 3. The physical channel assignment of group 3 is the entire S-CCPCH. The time slots assigned to Group 3 overlap with the time slots assigned to Group 1 and Group 2.

Still referring to Figure 4, it appears that an overlapping time slot and the time division of a time slot are brought into groups 4, 5, and 6 within a provided frame. Group 4 cells are assigned to the fourth time slot group TS in each frame<u style="single">1</u>, TS<u style="single">4</u>. Remaining time slot TS<u style="single">2</u>-TS<u style="single">3</u>And TS<u style="single">5</u>-TS<u style="single">n</u>Not used by group 4. The physical channel assignment of group 4 is the entire S-CCPCH. The cells of group 5 are assigned to the fifth time slot group TS in each frame<u style="single">1</u>And TS<u style="single">3</u>. Remaining time slot TS<u style="single">1</u>And TS<u style="single">4</u>-TS<u style="single">n</u>Not used by group 5. The physical channel assignment of group 5 is the entire S-CCPCH. The cells of group 6 are assigned to the sixth time slot group TS in each frame<u style="single">2</u>And TS<u style="single">4</u>. Remaining time slot TS<u style="single">1</u>, TS<u style="single">3</u>And TS<u style="single">5</u>-TS<u style="single">n</u>Not used by group 6. The physical channel assignment of group 6 is the entire S-CCPCH. One or more time slots of these groups overlap with the time slots of other groups. For example, the time slot TS assigned to group 1<u style="single">1</u>Time slot TS assigned to group 4<u style="single">1</u>And TS assigned to group 5<u style="single">1</u>overlapping. Similarly, the time slot TS assigned to group 1<u style="single">2</u>Time slot TS assigned to group 3<u style="single">2</u>And the time slot TS assigned to group 6<u style="single">2</u>overlapping. There is no overlapping time slot group between any two cell groups, so each cell group has its own unique time slot combination assigned to it.

During this time slot, communication is allowed to overlap with the time slots and frames assigned to the complex cell group. These combinations are such that there is no overlapping time slot or frame group between any two cell groups. This can provide each cell group with its own unique time slot and frame combination assigned to it .

Figure 5 shows an example of implementing time-domain reuse in an FDD system, where the multi-frame allocation of the TDD system (as shown in Figure 4) can be expanded to FDD. Figure 5 is a time-domain diagram showing frame allocation, where each cell group in a predetermined group of cell groups uses the same S-CCPCH. The channel described in Figure 4 refers to a specific frame for each cell group. However, the S-CCPCH of each group uses a shared frame. This assignment can be applied to all cell groups, but within a predetermined group of the cell group, the cells in each group are assigned to a unique S-CCPCH group. This modified technique can overlap frame assignments. This restriction is that within the predetermined group of the cell group, the cells in each group are assigned to a unique S-CCPCH group, and there is overlap between the S-CCPCH groups.

Referring to FIG. 5, the cells of group 1 are assigned to the first frame group that matches the frames 101 and 102. The remaining frames 103A and 103B are not used by group 1. The physical channel assignment 105 of group 1 is the entire S-CCPCH. The cells of group 2 are assigned to the second frame group that matches the frames 111 and 112. The remaining frames 113A and 113B are not used by group 2. The physical channel assignment 115 of group 2 is the entire S-CCPCH. The cells of group 3 are assigned to the third frame group that matches the frame 121 and the frame 122. The remaining frames 123A and 123B are not used by group 3. The physical channel assignment 125 of group 3 is the entire S-CCPCH.

Refer to Figure 5 and bring the used assignment overlaps into groups 4, 5, and 6. As can be seen in Figure 5, the cells of group 4 are assigned to the fourth frame group that matches the frames 131 and 132. The remaining frames 133A and 133B are not used by group 4. The physical channel assignment 135 of group 4 is the entire S-CCPCH. The cells of group 5 are assigned to the fifth frame group corresponding to frames 141 and 142. The remaining frames 143A and 143B are not used by group 5. The physical channel assignment 145 of group 5 is the entire S-CCPCH. The cells of group 6 are assigned to the sixth frame group corresponding to frames 151 and 152. The remaining frames 153A and 153B are not used by group 6. The physical channel assignment 155 of group 6 is the entire S-CCPCH.

During these frames, the communication is allowed to overlap with the frames assigned to the complex group of cells. These combinations are such that there is no overlapping frame group between any two cell groups. This can provide each cell group with its own unique frame combination assigned to it.

Referring to Figure 5, the FDD channel assignment for the cells in groups 1-4 is allowed to be TTI=20 milliseconds (which can be achieved by setting the S-CCPCH with the correct SFN). FDD is generally allowed to be used for asynchronous cell operations, and the use of asynchronous cell operations can make the channel assignment of the present invention easier to handle in terms of time. The cells in groups 5 and 6 need to use TTI=10 milliseconds.

According to the present invention, a time domain reuse factor for FDD transmission is provided. The introduction of this time domain reuse factor for DL common channels is particularly important for shared transmission situations (such as MBMS on S-CCPCH or DL shared channels). This principle is similar to the time domain used in TDD, but with continuous transmission in a special frame instead of a special TS per frame (such as in TDD).

In FDD, because continuous S-CCPCH or Downlink Shared Channel (DL DSCH) transmission is required in a special frame instead of a special TS per frame as in TDD, it is impossible to follow the conventional procedure (The same is equal to the pre-mentioned technique of TDD) is generally straightforward to expand.

Even if the same multi-frame allocation as in TDD does not exist in FDD, it can still be achieved by assigning the channel continuously (that is, each frame), but if it is not intended by the base station, it is not in some It is delivered in a special frame. The S-CCPCH does not need to include guidance bits, because the P-CCPCH is usually used as a phase reference, and no other control bits (such as TFCI) need to be sent when there is no data. Therefore, there is no need to transmit anything during these idle periods. Using different channel assignments associated with P-CCPCH channel assignments can provide a TDD technology equivalent to FDD.

According to the 3GPP W-CDM communication system, the present invention can use voice and data using video and high-speed downlink packet access (HSDPA) transmission. The 3GPP system can only be used as an example and the present invention can be applied to other code division multiple access communication systems. It should also be noted that the FDD part of the present invention can be applied to the conventional S-CCPCHS or DL shared channel examples in UMTS FDDR99 and later (for example, HS-DSCH in R5), regardless of specific content.

According to the present invention, what needs to be known is when the user terminates the service or when the service has been successfully received in order to efficiently release the entities and transmission resources assigned to the MBMS. The explicit MBMS revocation information generated by the user can be used to reduce MBMS transmission. This can be an L3 RRC program or a NAS signaling program. After receiving the revocation information, the user's MBMS content will be removed from the valid user currently related to the particular MBMS.

Referring to FIG. 6, an activation/deactivation method is used in the wireless multi-cell communication system 600, which includes a plurality of WTRUs 605 communicating with the UTRAN 610 to control the number of retransmission requirements for a particular MBMS.

The cancellation can be used for transmission switching to determine the number of users (WTRUs) currently receiving the MBMS. In this way, the channels of the communication system 600 can be recombined for better performance. Furthermore, the number of retransmissions can be reduced.

In a specific embodiment, the WTRUs 605 of Figure 6 operate in a specific cell of the communication system 600, which can activate the MBMS. The UTRAN 610 can determine the number of WTRUs 605 operating in a specific cell that can initiate MBMS. The UTRAN 610 can allocate resources to specific cells according to the determined number of WTRUs 605. The UTRAN 610 uses the allocated resources to spread the MBMS to the WTRUs 605. The UTRAN 610 will terminate the MBMS at the WTRUs 605, and will reallocate the resources of the UTRAN 610 when all the WTRUs 605 cancel the MBMS.

Subject to the number of effective users, UTRAN 610 can install transmission and physical channels to achieve maximum radio resource efficiency. The MBMS cancellation signal information can be used as an obvious sign, which can reduce the user count for each service subscribed by the user. When the number of users of special services reaches a predetermined limit, the transmission/physical channel switching can be performed. When all users have been revoked, the MBMS transmission will be terminated in this cell.

In step 615, the user can initiate MBMS by sending a signal from UTRAN 610 and its WTRUs 605. The MBMS may be distributed by UTRAN 610 to WTRUs 605 (step 620). When the user is removed from those valid users of MBMS (steps 625, 635), as a result, the UTRAN 610 can evoke MBMS transmission/physical channel switching (step 630) or can disperse the service in the cell discontinuously (step 640) .

Referring to Figure 7, the existing cell update procedure can also be used to activate and deactivate MBMS transmission. The cell update program used to track user migration can also be installed to update periodically. After the user's MBMS is activated (step 700), and because the valid MBMS user already knows, the cell update procedure can be executed on a periodic basis to determine when the user has moved to a new cell or cannot be accessed UTRAN 610 arrives (step 705), so the MBMS can be distributed to WTRUs 605 (step 710). When the cell update program shows that the WTRU 605 has moved to a new cell or that periodic updates about these users are no longer received by the UTRAN 610 (step 715), the users MBMS content can be changed from now to The specific MBMS-related valid users in the cell are removed, so that the MBMS transmission can be terminated (step 720).

In a specific embodiment, at least one of the WTRUs 605 in Figure 7 may activate the MBMS. The WTRU 605 may provide a periodic update to the network, which may indicate the first cell of the communication system in which the WTRU 605 is operating. The UTRAN 610 will spread the MBMS to the WTRU 605. When the WTRU 605 stops providing periodic updates or operates in a cell different from the first cell in the communication system, the UTRAN 610 terminates the MBMS at the WTRU 605.

Figure 8 shows a wireless communication system 800, which includes a plurality of WTRUs 805 communicating with a UTRAN 810 and a core network (CN) 815. System 800 may provide MBMS notification and optional delivery confirmation (step 820). For billing purposes, after the MBMS is distributed to the WTRUs 805 (step 825), the further MBMS delivery confirmation (step 830) reported by the WTRUs 805 to the UTRAN 810 can be enlarged to the CN 815 (step 835). Signaling can be achieved by UTRAN 810 sending certain information to WTRU 805, UTRAN 810 generating new information, or non-access layer node B application part (NAS) directly sending a signal from WTRU 805 to CN 815. After being received by CN 815, it records MBMS delivery for each WTRU 805. The confirmation information can be L3 Radio Resource Control (RRC) or NAS signaling information. UTRAN 810 can track and confirm each user who initiates those MBMS. Once all or a predetermined percentage of active users have confirmed the delivery, the retransmission can be terminated (step 840). The maximum retransmission count can also be installed to limit the use of radio resources to special MBMS.

In a specific embodiment, the UTRAN 810 of FIG. 8 may spread MBMS to at least one of the WTRUs 805 by sending a plurality of MBMS data transmissions. The WTRU 805 will indicate to the UTRAN 810 that all MBMS data transmissions have been received. Then, the UTRAN 810 will terminate the MBMS data transmission.

Service confirmation cannot always be confirmed. For example, some services have very little data per transmission. Therefore, the cost of retransmission is very small. One option allowed for this further optimization is to identify which service receives the transmission confirmation during the startup procedure.

Other methods for successful MBMS delivery with reduced retransmissions are to receive and store individual data segments from each transmission, and then combine these blocks from each retransmission until the MBMS service transmission is completed. The MBMS transmission contains a number of data segments, each of which contains one or more cyclic redundancy checks (CRCs) used to verify that it has been successfully delivered.

MBMS segmentation can be performed by the wireless communication system 900 shown in FIG. 9. System 900 includes at least one WTRU 905 communicating with UTRAN 910. After receiving the MBMS transmission (step 915), the WTRU 905 stores all successfully received data segments (steps 920, 925). The WTRU 905 may use the MBMS information to systematically receive only those data segments that were not successfully received in the previous transmission (e.g., segment 2) (step 930) instead of receiving the entire transmission. Therefore, WTRU processing and power consumption can be reduced. Additionally, the number of transmissions required for successful delivery can be reduced because it only needs to plan to receive segments that have not been successfully received, rather than plan to receive all MBMS transmissions. This MBMS segmentation can reduce the number of MBMS retransmissions or terminate the number, regardless of the selective MBMS delivery confirmation information generated by the user (step 935).

In a specific embodiment, the UTRAN 910 in FIG. 9 can divide the MBMS into a plurality of separate data segments, and can send each MBMS data segment to the WTRU 905. The WTRU 905 stores each MBMS data segment that has been properly received by the WTRU 905 in a memory (not shown). The WTRU 905 can identify to the UTRAN 910 at least one MBMS data segment that was not properly received by the WTRU 905. The UTRAN 910 will only retransmit the identified MBMS data segment to the WTRU 905.

Before transmitting these MBMS data segments, UTRAN 910 will indicate to WTRU 905 when each MBMS data segment will be transmitted to WTRU 905 and how many data segments the MBMS contains. Each MBMS data segment may include at least one cyclic redundancy check (CRC) used to verify that the MBMS data segment has been successfully delivered by the WTRU 905. The operator of the UTRAN 910 can determine whether the WTRU 905 has received all the MBMS data segments in order to facilitate payment.

In another specific embodiment, the UTRAN 910 divides the MBMS into a plurality of separate MBMS data segments, and is scheduled to be transmitted to the WTRU 905 at different times. The UTRAN 910 will indicate to the WTRU 905 the different planned time and how many data segments the MBMS contains. The UTRAN 910 will send the MBMS data segments to the WTRU 905 at different scheduled times. The WTRU 905 will activate its receiver (not shown) at different scheduled times to receive the MBMS data segment sent by the UTRAN 910. The WTRU 905 will identify the UTRAN 910 for at least one MBMS data segment that was not properly received by the WTRU 905. When the authenticated data segment is to be retransmitted to the WTRU 905, the UTRAN 910 will indicate to the WTRU 905 an allocated time. UTRAN 910 will only retransmit the authenticated MBMS data segment to the WTRU. The WTRU 905 will activate the receiver in it at the allotted time to receive the retransmitted MBMS data segment.

Although the present invention has been specifically shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes can be made in form and details without departing from the scope of the present invention as described above. .

<p>78. . . Frame A</p><p>80. . . Frame B, Frame N</p><p>300. . . program</p><p>101, 102, 103A, 103B, 111, 112, 113A, 113B, 121, 122, 123A, 123B, 131, 132, 133A, 133B, 141, 142, 143A, 143B, 151, 152, 153A, 153B. . . Frame</p><p>600. . . Wireless multi-cell communication system</p><p>605, 805, 905, WTRUs. . . Wireless transmission/receiving unit</p><p>610, 810, 910, UTRAN. . . Global terrestrial radio access network</p><p>800. . . Wireless communication system</p><p>815, CN. . . Core network</p><p>900. . . system</p><p>MBMS. . . Multimedia Broadcasting Service</p>

Figure 1 illustrates a typical data frame sequence used in the aforementioned communication system technology, where one frame contains fifteen time slots.

Figure 2 shows a channel assignment diagram used in the aforementioned communication system technology, in which unique time slots are applied to cells in different groups.

Figure 3 is a flow chart of allocating MBMS services to cells in a TDD or FDD wireless multi-cell communication system according to a specific embodiment of the present invention.

Figure 4 is an example diagram of performing time-domain reuse in a TDD communication system, where cells in different groups share a time slot with cells in other groups, but unique time-slot combinations can be applied according to the present invention To cells in different groups.

Figure 5 is an example of performing time-domain reuse in an FDD system, in which an overlapping assignment is used according to the present invention.

Figure 6 is a block diagram of a communication system (TDD or FDD), which can perform MBMS service cancellation according to a specific embodiment of the present invention to control transmission/physical channel switching and service termination.

Figure 7 is a block diagram of a communication system (TDD or FDD), which can execute a cell update procedure according to a specific embodiment of the present invention to control MBMS service transmission.

Figure 8 is a block diagram of a communication system, which can perform delivery confirmation to reduce MBMS transmission according to a specific embodiment of the present invention.

Figure 9 is a block diagram of a system that can perform MBMS segmentation according to a specific embodiment of the present invention.