Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/04—Large scale networks; Deep hierarchical networks
  • H04W84/08—Trunked mobile radio systems

Definitions

• the present invention relates to a wireless communication technology, and more particularly to a method for improving the performance of a trunked broadcast service service using a spatial diversity reception method in a wireless communication system.
• multimedia broadcast multicast service
• the MBMS service has the following characteristics: (1) The service needs to cover the entire cell as much as possible, and (2) the same service is broadcasted to a certain area of the network, for example, on multiple neighboring cells, (3) the data transmission rate is high.
• the MBMS service is carried by the secondary common control channel (SCCPCH) and not by the BCCH mapped on the common control channel PCCPCH.
• SCCPCH secondary common control channel
• the BCCH channel has similar characteristics to the SCCPCH channel carrying the MBMS service, only system information is carried on the BCCH channel.
• the data rate of the BCCH channel is only 12.3 kbps, which is much smaller than the data rate required by the MBMS service (64 kbps to 256 kbps).
• a high data rate requires the received signal to have a high carrier to interference ratio. Therefore, due to the limitation of downlink (DL) transmission power, the coverage of the MBMS service will be much smaller than the coverage of the BCCH channel.
• DL downlink
• the diversity gain can be obtained by combining non-correlated signals. Since the high rate services provided in neighboring cells are the same, the service coverage area can be expanded by combining signals from neighboring cells for users close to the cell boundary. Some diversity methods (space, time, frequency domain diversity) have been applied to increase the coverage area.
• FIG. 1 A schematic diagram of signal combining on a user equipment in accordance with the prior art is shown in FIG.
• User The antenna of the device receives the signals of different cells, transmits them to the diversity receiver, and then performs channel decoding, and then performs process coding based on the check code (CRC) and the sequence number, and finally transmits them to the application layer for regular processing.
• CRC check code
• WCDMA wideband Code Division Multiple Access
• macro diversity is used to increase coverage, i.e., the terminal establishes a link to some Node Bs and combines bursts of high rate services that broadcast the same content from cells of the above Node B.
• TDD time division duplex mode
• a similar macrodiversity method is also used, which combines signals from different cells in different time slots. For example, cell 1 transmits a high-rate service in which each cell broadcasts the same content in TS4 (time slot 4), and cell 2 transmits a high-rate service in which each cell broadcasts the same content in TS6.
• the terminal receives the high rate service bursts of the same content in each of the cells in TS4 and TS6 in the same frame and combines them.
• the diversity gain in the spatial and/or temporal domain is produced after merging.
• the diversity of the spatial domain is obtained by combining the signals in different propagation paths.
• Time domain diversity uses signals transmitted at different times with characteristics of uncorrelated transmission characteristics such as fading, through - and signals received at different time slots to obtain gain. Since other cells transmit the traffic channel (TCH) on the same time slot together with the above cells, the TCH in one slot and the high rate service in which each cell broadcasts the same content will interfere with each other.
• TCH traffic channel
• Another method uses the frequency domain and the time domain to obtain gain, that is, different cells transmit the same cluster broadcast service burst at different carrier frequencies and different time slots.
• the user terminal combines burst broadcast traffic bursts from different carrier frequencies and time slots. This will reduce spectral efficiency because multiple bursts need to be reserved for the same cluster broadcast service block.
• the TCH and trunk broadcast services that are also transmitted in neighboring cells will interfere with each other. Summary of the invention
• a method for improving performance of a trunked broadcast service using a spatial diversity receiving method comprising the steps of:
• the transmitting end After determining that the service transmitted on the current time slot is a trunking broadcast service, the transmitting end allocates the same scrambling code or no scrambling code to the data part of the cluster broadcast service burst;
• the receiving end uses the training sequence for channel estimation, and receives and merges the bursts, thereby Get the spatial diversity gain.
• each cell uses a different basic training code for channel estimation.
• each cell uses the same training code but a different training offset for channel estimation.
• all cells use the same basic training code for channel estimation.
• the receiving end merges the bursts together using one of a maximum ratio combining method, a selection combining method, or an equal gain combining method.
• the present invention combines signals of different frequencies at the radio link control layer based on the signal check code and the sequence number.
• the present invention also includes the steps of channel decoding the received cluster broadcast service signal, and the step of conventional processing of the signal of the gain by the application layer of the user terminal.
• FIG. 1 is a schematic diagram of diversity combining received signals on a user terminal according to the prior art
• FIG. 2 is a schematic flowchart of a method according to the present invention. detailed description
• Multimedia Broadcast Multicast Service is a typical cluster broadcast service.
• MBMS Multimedia Broadcast Multicast Service
• the following description of the present invention is specifically directed to the MBMS service, but it can be understood that any service having the trunk broadcast characteristic can adopt the technical solution of the present invention, as long as it has the characteristics of broadcasting the same service in different cells, The technical solution of the present invention can be applied.
• the transmitting end allocates the same scrambling code to the data portion of the MBMS burst, and then transmits the scrambling in the same time slot in the network. After the sudden.
• the MBMS bursts from different cells experience different attenuation paths, so spatial diversity can also be automated. If the path from the target cell is in a very strong fading and the path from the neighboring cell is not fading, the receiver can also decode the MBMS information in the burst with weaker fading.
• the scrambling code is not assigned at all, depending on the ease of process design and software design, the corresponding workload, and the configuration of the system.
• the receiving end After the scrambling process is completed at the transmitting end, according to the present invention, the receiving end performs corresponding system processing according to the above processing conditions to improve the spatial diversity gain of the signal.
• the receiving end performs channel estimation using the training sequence to receive and combine bursts, thereby obtaining a spatial diversity gain of the signal. Since the basic training codes for channel estimation in different cells are usually different, the following three solutions can be used to solve the channel estimation problem:
• each cell uses a different basic training code.
• the terminal in the target cell will use the specified training code for channel estimation.
• the channel estimation only the multipath between the target terminal and the target node B can be estimated, and paths from other cells cannot be used, so that interference between the respective cells can be appropriately reduced, thereby obtaining spatial diversity gain.
• Each cell uses the same training code but a different training offset.
• the length of the training sequence in a TD-SCDMA system is 128 chips. If the maximum delay of the set channel is 16 chips, there can be up to 8 training sequence offsets. Can allocate 7 different for every 7 cells The offset, and reuse the offset in other cells, similar to the frequency reuse factor of 7 in the frequency plan. Subsequently, the terminal will estimate the channel impulse response using the different training offsets described above, and the terminal can obtain 7 re-recovered MBMS bursts, and will use the maximum ratio combining method, the selection combining method or the equal gain combining method to The hairs are merged together to obtain a larger spatial diversity gain.
• Option 3 All cells use the same basic training code. MBMS bursts from different Node Bs will be identical, including the data portion and the training portion. Bursts arriving at the receiving end antenna of the target terminal will be automatically merged. The user terminal will estimate the channel impulse response in a channel estimation window. This also gives the spatial diversity gain.
• the spatial diversity method of the present invention By adopting the spatial diversity method of the present invention, spectrum efficiency can be improved, cells can be prevented from interfering with each other, and decoded signal quality can be improved, thereby increasing coverage and reducing the number of required site layouts.
• the method of the invention realizes the single order, the product hardware has no change, only the scrambling code/training code is changed, so it can be carried out in the network planning stage.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Radio Transmission System (AREA)

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• 2005
  • 2005-09-30 CN CNB2005101074183A patent/CN100555903C/zh not_active Expired - Fee Related
• 2006
  • 2006-09-25 KR KR1020087010402A patent/KR100960205B1/ko not_active IP Right Cessation
  • 2006-09-25 JP JP2008532567A patent/JP4779019B2/ja not_active Expired - Fee Related
  • 2006-09-25 WO PCT/CN2006/002523 patent/WO2007036145A1/zh active Application Filing

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