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
  • H04B7/12—Frequency diversity
• • 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
  • H04B7/022—Site diversity; Macro-diversity
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/30—Resource management for broadcast services

Definitions

• the present invention relates to a method for improving service performance of a trunk broadcasting service in a mobile communication system, and more particularly to a method for expanding a coverage area of a trunk broadcasting service by using a frequency diversity gain in a wireless communication system.
• MBMS multimedia broad ⁇ cast multicast service
• 3GPP TR 25.803 the third generation mobile communication standard 3GPP TR 25.803 for further information
• the MBMS has the following characteristics: (1) the service needs to cover the entire cell as much as possible; (2) the same service is broadcasted to a certain area of the network, for example, multiple adjacent cells; (3) the data transmission rate is relatively high.
• BCCH broadcast channel
• PCCPCH primary common control physical channel
• SCCPCH secondary common control physical channel
• the BCCH only carries system information.
• the BCCH has a data rate of only 12.3kbps, which is far less than that required by the MBMS (for example in the range of 64kpbs to 256kpbs) .
• a high data rate requires a received signal to have a high carrier to interfer ⁇ ence ratio.
• the coverage area of the MBMS is far smaller than that of the BCCH, and the higher the data rate of the MBMS, the smaller the coverage area of the MBMS.
• this method will increase network operating costs, capital input and expenditure.
• An object of the present invention is to provide a method capa ⁇ ble of enhancing trunking broadcast receiving capability and hence improving the coverage ratio of a trunk broadcasting service .
• a method for improving service performance of a trunk broadcasting service in a mobile communication system characterized in that it comprises the following steps:
• Said trunk broadcasting service signal is a multimedia broad ⁇ cast multicast service signal.
• the trunk broadcasting service signal can be transmitted in different time slots, the different time slots being set as at a certain distance, for example within one frame or between two consecutive frames of time slots; additionally, the said different frequencies being set at a certain distance to decrease the correlation between the signals.
• the combining method used in the present invention can be se ⁇ lected from a group consisting of a selective combining method, a maximum ratio combining method, and an equal-gain combining method.
• the present invention further comprises the step of performing channel decoding on said trunk broadcasting service signals re ⁇ ceived, and the step of performing conventional processing on said signal with a gain by the application layer of the user terminal .
• the signals of different frequencies are combined at the radio link control layer based on signal check codes and serial numbers.
• Figure 1 is a schematic diagram illustrating combination of diversity received signals at a user terminal according to the prior art
• Figure 2 is a schematic diagram illustrating transmission of different frequencies in different time slots and combination thereof according to the present invention.
• many methods can be used to enhance the receiving capability of a terminal; for example, the receiving capability of the terminal can be enhanced by in ⁇ creasing transmitting power of a transmitting end, and/or increasing receiving power of a receiving end.
• these methods all require system equipment to be modified on a rela ⁇ tively large scale, which will need a very large capital input and lead to very high cost as well.
• signal receiving capability can be enhanced by modification without significantly adding equipment.
• the present invention is achieved by enhancing diversity receiving capability of a receiving end and obtaining a diversity gain.
• Diversity reception refers to a method for, by a receiving end, performing particular processing on a plurality of signals the receiving end receives, each having a fading characteristic independent of others, so as to reduce level fluctuation of a signal.
• the diversity gain can be obtained by combining uncorrelated signals.
• Figure 1 shows a schematic diagram illustrating combination of signals at a user terminal. An antenna of the user terminal receives signals from different cells, which are then transmitted to two different diversity receivers to be decoded, and then are coded based on check codes and serial numbers, and finally are transmitted to the application layer for conventional processing.
• the coverage area of the service can be increased by combining signals from adjacent cells.
• a user can receive signals from the local cell and adjacent cells to perform subsequent signal combination.
• a spatial diversity gain and/or a diversity gain in the time domain can be generated.
• the spatial diversity gain can be obtained by combining signals from different transmission paths; and, based on the fact that the same signal, when being transmitted in different time, will ex ⁇ hibit uncorrelated transmitting characteristics, such as fad ⁇ ing, the diversity gain in the time domain can be obtained by combining signals received in different time slots.
• the method of the present invention is for obtaining a frequency diversity gain using frequency combination, and thus can enhance receiving capability of a user terminal.
• each cell has at least two sub-carriers.
• a sys ⁇ tem with two sub-carriers is described, and the same data are transmitted by two sub-carriers of different frequencies.
• the correlation between the two sub-carrier signals be as small as possible, so that a receiver can combine a plurality of independent fading signals it receives to reduce the effect caused by fading. Therefore, it is desired that the frequency difference between the two sub-carriers be as large as possi ⁇ ble, so as to avoid correlation between the sub-carriers.
• a receiver of a user terminal receives the two carrier signals of different frequencies, and combines the two carrier signals according to a combining method to obtain better decoding performance.
• the combining method employed by the present invention is well- known in the art; for example, it can be a selective combining method, a maximum ratio combining method, or an equal-gain combining method.
• One skilled in the art can select an appropriate combining method according to particular circumstances .
• an increase in the diversity gain can be obtained, thereby the capability of the receiving end to receive a signal can be significantly im ⁇ proved, and thus the coverage area of the MBMS can be expanded.
• the transmitter or transmitters in order to make the non-correlation between the received data larger, can even transmit in different time slots on said two different sub-carriers, and can set the interval between the transmission time slots on said two sub-carriers to a certain size, for example to be as large as possible, so as to reduce the correlation between signals in time domain.
• a time division du ⁇ plex (TDD) network with a data rate of 1.28Mcps
• sub-carrier 1 (Fl) of cell A is set to be transmitted in time slot TS4, while sub-carrier 2 (F2) of cell A or B, i.e.
• FDD frequency division duplex
• the user terminal can not only combine signals transmitted by the two sub-carri ⁇ ers of the local cell but also combine signals transmitted by the two sub-carriers of both the local cell and adjacent cells.
• the diversity gain is not only from the frequency domain but also can be from the time domain.
• the method according to the present invention can be used to improve the receiving performance for a multimedia broadcasting service, and hence increase the cell coverage ratio of the ser ⁇ vice and decrease the number of stations of the network needing to be provided.
• This method can also be used in conjunction with other methods, such as time slot multiplexing, to further improve performance.
• the present invention can not only be applied to a 1.28Mcps TDD system but can also be applied to a 3.84Mcps TDD system, a WCDMA system and the like.
• the number of sub-carriers may be two or more, depending on the characteris ⁇ tics of the cell and the design of the network.

Landscapes

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

Applications Claiming Priority (2)

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Citations (3)

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• 2005
  • 2005-09-30 CN CN2005101077995A patent/CN1941948B/zh not_active Expired - Fee Related
• 2006
  • 2006-09-22 EP EP06793758A patent/EP1935116A1/de not_active Withdrawn
  • 2006-09-22 WO PCT/EP2006/066644 patent/WO2007039494A1/en active Application Filing

Patent Citations (3)

Non-Patent Citations (2)

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