Methods and apparatus for cellular broadcasting and communication system
View Patent ↗In a cellular wireless network, methods and apparatus are disclosed for a signal broadcasting scheme that can be individually augmented for users with poor reception. The network employs a first downlink channel for broadcasting data to all mobile stations, a second downlink channel for sending signals to a specific mobile station in a cell, and an uplink channel for feeding back information to the base station. To achieve a certain user reception quality, the system adjusts its broadcasting parameters based on the statistical analysis of the feedback data. If some users still require better reception, the system individually augments their broadcast signals via the second downlink channels. Methods and apparatus are also disclosed for synchronization of data distribution by base stations, which, in part, allows the receivers to combine the receiving signals and improve their reception quality.
1. A method for data communication by a control server connected via a packet data network (PDN) to a plurality of base stations in a plurality of cells, the plurality of base stations having synchronized timing of radio transmission frames and capable of transmitting data using a same time-frequency resource in a single frequency network (SFN), the method comprising:
receiving broadcast data to be transmitted by the plurality of base stations via wireless packets contained in radio transmission frames, each radio transmission frame including a plurality of subframes;
forming distribution data packets, each distribution data packet comprising a synchronization protocol header and broadcast data, the synchronization protocol header providing information to the plurality of base stations to identify a radio transmission frame and enable transmission of the broadcast data with the same time-frequency resource in subframes over the SFN, wherein a subframe may contain a plurality of wireless packets, the synchronization protocol headers including:
a time synchronization parameter indicating a start time for the transmission of the broadcast data; and
a packet sequence number that, when interpreted in conjunction with the time synchronization parameter, enables each of the plurality of base stations to restore a sequential order of its received distribution data packets; and
distributing the distribution data packets via the PDN to the plurality of base stations for transmission of the broadcast data by the plurality of base stations.
2. The method of claim 1 , wherein a synchronization protocol header is inserted in the beginning, in the middle, or at the end of a data payload containing broadcast data.
3. The method of claim 1 , wherein the time synchronization parameter is set at a time in the future that accounts for the maximum transmission delay in the PDN.
4. The method of claim 1 , wherein the time synchronization parameter is specified using a time unit related to a transmission time interval.
5. The method of claim 4 , wherein the transmission time interval is specified with respect to a radio transmission frame.
6. The method of claim 5 , wherein the transmission time interval is specified as a radio transmission subframe.
7. The method of claim 5 , wherein the radio transmission frame contains orthogonal frequency division multiplex (OFDM) signals.
8. The method of claim 5 , wherein a length of the radio transmission frame is 10 ms.
9. The method of claim 1 , wherein the time synchronization parameter is specified in a bit field in the synchronization protocol header.
10. The method of claim 1 , wherein the packet sequence number facilitates detection of the loss of a data packet at each of the plurality of base stations.
11. The method of claim 1 , wherein a value of the packet sequence number is specified in a bit field in the synchronization protocol header.
12. The method of claim 11 , wherein the bit field has a sufficient width to specify a maximum number of packets in a transmission period.
13. The method of claim 1 , wherein a cyclic redundancy check (CRC) or checksum field is added to the distribution data packet.
14. The method of claim 1 , wherein the data distribution network is either a wired network or a wireless network.
15. A data distribution system for distributing broadcast data via a packet data network (PDN) to a plurality of base stations in a plurality of cells, the plurality of base stations having synchronized timing of radio transmission frames and capable of transmitting data using a same time-frequency resource in a single frequency network (SFN), the data distributing system comprising:
an apparatus configured to receive broadcast data to be transmitted by the plurality of base stations via wireless packets contained in radio transmission frames, each radio transmission frame including a plurality of subframes;
an apparatus configured to form distribution data packets, each distribution data packet comprising a synchronization protocol header and broadcast data, the synchronization protocol header providing information to the plurality of base stations to identify a radio transmission frame and to transmit the broadcast data with the same time-frequency resource in subframes over the SFN, wherein a subframe may contain a plurality of wireless packets, the synchronization protocol headers including:
a time synchronization parameter indicating a start time for the transmission of the broadcast data; and
a packet sequence number that, when interpreted in conjunction with the time synchronization parameter, enables each of the plurality of base stations to restore a sequential order of its received distribution data packets; and
an apparatus configured to distribute the distribution data packets via the PDN to the plurality of base stations for transmission of the broadcast data by the plurality of base stations.