Radio network controller for multimedia broadcast and multicast services channel switching

Wireless network controller for multimedia broadcast and multicast service channel switching

Creative field

This creation is generally about wireless communication systems, especially this creation is about channel switching and scheduling of multimedia broadcast and multicast services in the system.

Creative background

The demand for using multimedia broadcast/multicast services (MBMS) in wireless communication systems is on the rise. For a specific MBMS, a granted cell in the network may have none, one, or multiple users, wireless transmission/reception Units (WTRUs) use this MBMS. When users migrate between cells, a cell that may have one or no users using the service may later have multiple users using the service. On the contrary, one has multiple users using the service at one point. Of users may have only one or no users at another time.

The migration of users will result in inefficient use of wireless resources. If only one or a few users use the MBMS in this cell, it is worthwhile for users to use the dedicated channel to use the service. The dedicated channel can use power control and beam steering to reduce the radio resources used to use MBMS quantity^。

However, if too many users use MBMS in this cell, a considerable amount of wireless resources may be used in the total of multiple dedicated channels. In this case, a more ideal wireless resource usage may be through a shared/shared Channel to send MBMS data to a group of users who use the MBMS. Although the use of beam steering and power control will be restricted in this situation, the reduction in the total number of channels can reduce the use of radio resources. When the number of MBMS users in the cell changes, the original choice of either shared/shared channels or dedicated channels will not be so ideal in the future.

Another potential problem caused by user migration is MBMS scheduling.

When an MBMS user moves between cells, the user needs to re-establish the MBMS service by receiving the information from the two cells. If the two cells synchronize their MBMS transmission, the MBMS user can have no gaps between the cells However, similar scenarios are usually not realized and will be disappointing. Under a certain degree of time gap based on cell loading and effective resources, one cell may have more effective resources to support MBMS transmission at a certain time than at another time. Therefore, let the cell at that time It is satisfactory to transmit a larger amount of MBMS data. For another cell at the same time slot, resources supporting the same MBMS bandwidth will not exist. Therefore, it is quite desirable to schedule different MBMS transmissions between cells to make more effective use of this resource. When an MBMS user moves between cells, the new cell that the user moves into is transmitted either before or after the transmission of another cell. Therefore, the MBMS user may miss MBMS data or receive unnecessary and redundant MBMS data.

Therefore, making MBMS have better resource utilization has become what everyone desires.

Creation overview

A wireless network controller includes an input, which is configured to receive a multimedia broadcast/multimedia service (MBMS) data; an input, which is configured to receive a radio communication link with an MBMS service entity Established, the service entity recognizes a specific MBMS service of the MBMS data; and an MBMS channel switching device for determining whether the MBMS data should be mapped to a dedicated channel or a share in terms of a specific cell /Share the channel, and map the MBMS data to a channel determined by one of the specific cells, and the determined channel is based on multiple users of the specific cell. The MBMS channel switching device further includes an output, which is configured to generate a dedicated channel or a shared/shared channel according to the channel determination.

Preferred embodiment

Although the description of the preferred embodiment is combined with the Third Generation Partnership Project (3GPP) Wideband Code Division Multiple Access (W-CDMA) system, the embodiment is also applicable to any wireless system using MBMS, and subsequent wireless transmission/reception A unit (WTRU) includes, but is not limited to, a user equipment, a mobile base station, a fixed or mobile subscriber unit, a pager, or any device that can operate in a wireless environment.

Figure 1 is a flow chart for switching MBMS channels. In a particular cell, the number of WTRUs using the service is determined or estimated in step 20. Typically, this information is unknown. The number of WTRUs used in the cell and/or other cell information, such as cell status, available cell resources, etc., whether to use dedicated channels or shared/shared channels or both , Namely step 22. After the channel selection is determined, the MBMS data will be mapped to the corresponding channel (step 24). A possible approach to determine what type of channel is used is a threshold test. If the number of WTRUs in the cell is below a certain value, a dedicated channel is used, which allows power control and uses transmission difference technology. These technologies are expected to use available resources efficiently when MBMS transmission of high data rate occurs.

If the number of WTRUS exceeds the threshold, a shared/shared channel is used, such as a shared channel, a high-speed shared channel, or an auxiliary shared control entity channel (S-CCPCH). A shared channel or high-speed shared channel can be used to simultaneously transmit MBMS data to multiple WTRUs, while S-CCPCH can be used to broadcast MBMS data to multiple users. Typically, the shared/shared channel has lower wireless Resource efficiency.

In another embodiment, a two-threshold approach is used. If the number of WTRUs using MBMS in the cell is lower than the first threshold, use dedicated channels; if the number is between the first and second thresholds, use shared or high-speed shared channels; if the number exceeds the second threshold The threshold value is to use a shared channel to broadcast MBMS.

In some situations, it may be more desirable to use shared and dedicated channels to support MBMS. To illustrate, many used WTRUs may be located together, such as a row of base stations, and a few or a single WTRU may be outside a row of base stations. In this case, the most efficient use of cell resources to support MBMS may be Assign a shared channel to a list of WTRUs on the base station, and assign a dedicated channel to other WTRUs. When the number of users in the cell changes, the cell status changes or the channel selection will periodically reuse the new information, that is, step 26.

Figure 2 is an illustration of a preferred radio access network (RAN) for performing channel switching. The RAN is composed of a service network controller (S-RNC) 30 that manages user services and a management cell entity The resource control is managed by the radio network controller (C-RNC) 34, which provides coordination between S-RNCs 30 and C-RNC 34 so that the signal sending process of the RAN over the local operation will be used.

A channel switching entity (MBMS channel switching device 36) decides which channel to use, such as dedicated, shared or shared, provides MBMS transmission and it also coordinates WTRUs 40_lUp to 40_N(40) MBMS is received, and the MBMS data is sent to WTRUs 40 through Node B 38.

A preferred implementation of channel switching is as follows. A first MBMS-enabled WTRU 40 can enter and leave the cell autonomously, which is related to the distribution and activation status of MBMS services. When MBM is the first WTRU 40 or When a small number of users in a specific cell are established, the dedicated channel will be established with a unique radio link (RL) indicator that recognizes the MBMS service. A second WTRU 40 that wants to use another MBMS will have a different dedicated channel assignment. For the user, when the RL is established for each user, a unique MBMS indicator is sent back from S-RNC 30 to C-RNC 34. The MBMS indicator is the same for each service provided to the user. It is unique. The C-RNC 34 maintains a database of all users in use for a specific MBMS service, and the group is recognized as an MBMS user group.

The data of each activated MBMS service will be distributed by the core network 28 to the C-RNC 34 through the MBMS data stream. A unique identifier connected to each MBMS data stream allows the C-RNC 34 to connect the data with the excessive Users or user groups so that the profile can be routed appropriately. According to the number of activated users and cell status of a particular MBMS service, the C-RNC 34 will determine whether the service should be transmitted on a dedicated or shared/shared channel.

Since individual users enter or leave the cell automatically, the switching between dedicated and shared channels is dynamic and may occur during uninterrupted transmissions.

Dynamic switching can be applied to the downlink shared channel (DSCH), and the data can be sent on the DSCH for a single user related to the dedicated DSCH (C-DSCH) or simultaneously by multiple users related to the shared DSCH (C-DSCH) take over.

For a particular MBMS, when only one user or a few users leave within the cell, the DSCH will become D-DSCH for the users. When the number of users related to the particular MBMS increases, the MBMS user group will Establish C-DSCH.

When the first WTRU 40 becomes activated between cells, a D-DSCH will be established for the first user, and MBMS transmission may not need to be continuously activated. The MBMS transmission on the DSCH will be indicated to the connected dedicated channel For the first WTRU 40 above, this indication can be turned on or off on a transmission time interval (TTI) basis.

C-DSH may be substantially the same as D-DSCH, but the difference is that the DSCH transmission signal of individual users related to the dedicated channel in the MBMS user group is synchronous transmission, which allows the MBMS user group All users in can receive a common DSCH transmission. An indicator will send out a signal along with the MBMS transmission to instruct the MBMS transmission to be used by a specific user or general user in the MBMS user group to achieve proper operation of the power control technology, transmission diversification, or any other unique Physical transport characteristics. The MBMS conversion between dedicated DSCH and general DSCH is clearer than that of WTRU40.

In another embodiment, channel switching is applied to high-speed DSCH (HS-DSCH). The difference of using HS-DSCH to replace DSCH is that it does not use synchronous allocation on the relevant dedicated channel of C-RNC34, and its synchronous allocation uses the HS-DSCH control channel of Node B 38.

In another embodiment, the conversion can occur between the dedicated physical channel and the general physical channel without using the related dedicated channel. The channel switch between the dedicated channel and the general channel will be clearly signaled to each user. The third layer protocol of RAN allows the procedure of the conversion between the transmission radio range and the dedicated and general channels. The signal transmission is performed by sending the converted radio range or by sending the transmission schedule information. Figures 3 and 4 are flowcharts that allow different cells and different intracellular MBMS transmissions to be sorted into different sequences. For the sake of illustration, suppose that a first cell can transmit a large amount of MBMS data to WTRUs in one radio band, but a second cell cannot. As a result, the MBMS transmission in the first cell may precede the second cell by one or more times. Multiple radio bands or TTIs.

To illustrate the inner cell located in the cell, a group of users is located in a train station and receives the service of the general dsch, while another user in the same cell is located outside the train station and receives a dedicated channel Or dedicated dsch service to make full use of radio wave form and power control. Depending on the DSCH load and other factors, the transmission of the WTRUs 40 at the railway station leads or lags behind the transmission outside the WTRU, which is satisfactory. If a user located outside of WTRUs enters a train station, it is most likely to switch WTRU40 to normal DSCH satisfactorily, and release the dedicated channel. In this case, the external WTRU 40 needs to catch up with the general DSCH transmission, or allow the transmission to catch up with the segment that the WTRU 40 has received.

In order to maintain continuous service allocation and use radio resources more efficiently, MBMS transmission is preferably segmented or scheduled so that users can receive the elements of MBMS service transmission under any circumstances. Therefore, the MBMS service transmission does not need to be re-initialized on the cell on the user channel, and the user does not need to wait for synchronization with the existing MBMS service transmission.

Figure 3 shows the use of in-band segment information to control the different MBMS transmission sequence of intra-cells or between cells. Follow the MBMS transmission, the section information is transmitted along with the MBMS data, step 42. The section information typically includes a section discriminator so that each receiving WTRU can identify the received section. When a specific WTRU moves between MBMS transmission sources (between cells or switching channels), step 44, the WTRU can receive segments from the new MBMS source and reorganize the transmission to recover all MBMS data, step 46.

Figure 5 is a simplified block diagram of WRTU40 receiving different MBMS transmissions. WRTU40 uses an antenna 54 to receive MBMS transmissions. The MBMS receiver 56 receives MBMS transmissions from different transmission sources, which include in-band segment information. A section information recovery device 58 is used to recover section information. Using segmentation information and receiving MBMS segments, an MBMS segmentation and reassembly device 60 restructures segments to recover MBMS data.

Figure 4 is a flow chart of using out-of-band transmission schedule information to control the transmission sequence of different MBMSs. The WTRU receives the MBMS transmission from a specific source, step 48. The WTRU also receives out-of-band scheduling information, step 50. When the WTRU moves to a different source, the WTRU can receive the MBMS data from the new source and use the out-of-band scheduling data from the source to reorganize the MBMS receive segment, step 52.

Figure 6 is a simplified block diagram of WRTU receiving different MBMS transmissions. The WTRU 40 uses an antenna 54 to receive MBMS transmissions. The MBMS receiver 64 receives MBMS transmissions from different transmission sources. An out-of-band synchronization information device 62 receives synchronization information from multiple transmission sources. Using the synchronization information and receiving the MBMS section, the MBMS splitting and reorganizing device 68 reorganizes the section to recover the MBMS data.

The methods in Figures 3 and 4 both allow users located in cells to switch between dedicated and normal channels without interrupting or delaying MBMS transmission. In addition, even if the transmission sequence between the new cell and the old cell is different, the WTRU entering the cell can still continue to receive the MBMS service. Once the MBMS transmission data is received, WRTU will record the information according to the in-band segment and/or out-of-band transmission schedule information.

Due to the application of intra-band segmentation or out-of-band scheduling, lost or failed transmissions can be efficiently recovered by the WTRU's use in retransmissions. The RNC MBMS retransmission schedule can also be reduced by taking into account the conversion and reception of WTRUs. Furthermore, if the RNC knows that all users have received a specific MBMS segment, the retransmission of that segment can be prevented.

<p>Figure 1: A flow chart of MBMS channel switching.</p><p>Figure 2: A better radio access network (RAN) for performing channel switching</p><p>Figure. The icon.</p><p>Figure 3: This is the MBMS from multiple sources using in-band zone information</p><p>Collaborative reception flowchart.</p><p>Figure 4: This is the result of MBMS from multiple sources using out-of-band segment information</p><p>Collaborative reception flowchart.</p><p>Figure 5: One of the MBMS information used to receive segment information in the used frequency band</p><p>WRTU.</p><p>Figure 6: One of the MBMS information used to receive out-of-band synchronization information</p><p>WRTU.</p>