System and method for broadcasting data over a wireless network

• US 20070223620A1
• Filed: 03/21/2006
• Published: 09/27/2007
• Est. Priority Date: 03/21/2006
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Nicolas, Julien, Kalhan, Amit
• Granted Patent: US 7,664,198 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

A system and method for broadcasting content data to a plurality of mobile devices is disclosed. The content data may be video, image, or audio data, for example. The content data is arranged into data blocks, and each data block is broadcast using an initial set of rateless transmission symbols. Mobile devices that did not receive a sufficient number of initial symbols respond with a NACK message, and a NACK rate for the broadcast system is monitored. Responsive to the NACK rate, additional symbols may be broadcast or otherwise transmitted to mobile devices, and, the NACK rate is used to determine when to terminate transmission of additional symbols for a particular data block. An initial set of symbols for the next data block may be transmitted concurrently with the additional symbols for one or more previous data blocks. The NACK rate may also be used as feedback to the broadcast system to adjust the transmission scheme.

Claims

1. A method for broadcasting data to a plurality of mobile devices using a wireless network, comprising:

arranging the data into a plurality of data blocks;

broadcasting an initial set of rateless transmission symbols indicative of a first one of the data blocks;

determining a NACK rate for NACK responses received from mobile devices that did not receive sufficient initial symbols;

evaluating the NACK rate to determine if additional transmission symbols are to be broadcast;

transmitting, responsive to evaluating the NACK rate, additional rateless transmission symbols indicative of the first data block; and

terminating, responsive to evaluating the NACK rate, transmission of additional symbols for the first data block.

2. The method according to claim 1, wherein the additional rateless transmission symbols are transmitted when the NACK rate is evaluated to be meaningfully declining.

3. The method according to claim 1, wherein the transmission of additional rateless transmission symbols is terminated when time for transmitting the first block has expired.

4. The method according to claim 1, wherein the transmission of additional rateless transmission symbols is terminated when the NACK rate is evaluated to be nearly constant.

5. The method according to claim 1, wherein the transmission of additional rateless transmission symbols is terminated when the NACK rate has passed its peak and is evaluated to be not declining.

6. The method according to claim 1, further Including the step of using the NACK rate to adjust transmission parameters for transmitting the additional symbols.

7. The method according to claim 1, further including the step of using the NACK rate to adjust transmission parameters for transmitting an initial set of rateless transmission symbols indicative of a second one of the data blocks.

8. The method according to claim 1, further including the steps of:

extracting transmission quality information from the NACK responses; and

using the extracted transmission quality information to adjust transmission parameters for transmitting the additional symbols.

9. The method according to claim 1, further including the steps of:

extracting transmission quality information from the NACK responses; and

using the extracted transmission quality information to adjust transmission parameters for transmitting an initial set of rateless transmission symbols indicative of a second one of the data blocks.

10. The method according to claim 1, further including the step of using the NACK rate to determine how many transmission symbols to broadcast in an initial set of rateless transmission symbols for a second one of the data blocks.

11. The method according to claim 1, further, including the step of using the NACK rate to adjust the transmission scheme for broadcasting a next initial set of rateless transmission symbols.

12. The method according to claim 1, further including the step of using the NACK rate to switch some of the mobile devices to a unicast mode, so that the switched mobile devices use a unicast mode to receive a next initial set of rateless transmission symbols.

13. The method according to claim 1, further including the step of using the NACK rate to allocate network resources between broadcast mode and unicast mode.

14. A method for receiving broadcast data, the method operation on a mobile wireless device, comprising:

(a) receiving a broadcast data packet having rateless transmission symbols indicative of a portion of a first data block;

(b) setting an initial time period;

(c) receiving, during the initial time period, further data packets having rateless transmission symbols indicative of a portion of a first data block;

(d) determining, after the initial time period, if sufficient transmission symbols have been received to generate the first data block;

(e) sending a NACK response if insufficient transmission symbols have been received;

(f) receiving additional data packets having additional transmission symbols indicative of a potion of the first data block;

(g) determining, after an additional period of time, if sufficient transmission symbols have been received to generate the first data block;

(h) sending an additional NACK response if insufficient transmission symbols have been received; and

(d) repeating steps (f), (g) and (h) until at least one of sufficient transmission symbols have been receive and time for receiving block one has expired.

15. The method according to claim 14 wherein the setting step includes determining the sequence number for the data packet.

16. The method according to claim 14 wherein sending the NACK response comprises sending transmission quality information.

17. The method according to claim 16 wherein sending the transmission quality information comprises sending SNR information.

18. The method according to claim 14 further including the step of concurrently receiving:

broadcast data packets having rateless transmission symbols indicative of a portion of a second data block; and

the additional data packets having additional transmission symbols is indicative of a potion of the first data block.

19. A method for broadcasting data to a plurality of mobile devices using a wireless network, comprising:

arranging the data into a plurality of data blocks;

determining a number of rateless transmission symbols to initially broadcast for each data block;

broadcasting an initial set of rateless transmission symbols for each one of the data blocks;

monitoring a NACK rate for each respective data block; and

transmitting additional rateless transmission symbols for each respective data block according to the monitored NACK rate.

20. The method according to claim 19, wherein the step of transmitting additional rateless transmission symbols for each respective data block is done according to the following conditions:

when the respective NACK rate is nearly constant or constant, terminating transmission of additional transmission symbols for that respective data block;

when the respective NACK rate continues to meaningfully decline, continuing to transmit additional transmission symbols for that respective data block;

when the respective NACK rate is below a predetermined threshold, terminating transmission of additional transmission symbols for that respective data block; and

when time has expired to transmit the respective data block, terminating transmission of additional transmission symbols for that respective data block.

21. The method according to claim 19, further including the step of monitoring the NACK rate for a peak NACK rate, and only terminating the transmission of additional transmission symbols at a time after the peak.

22. The method according to claim 19, further including the step of adjusting the number of rateless transmission symbols to initially broadcast according to the monitored NACK rate.

23. The method according to claim 19, further including the step of using the monitored NACK rate to adjust transmission parameters for transmitting the additional symbols.

24. The method according to claim 19, further including the step of receiving transmission quality information along with NACK responses, and using the transmission quality information to adjust transmission parameters for transmitting the additional symbols.

25. The method according to claim 19, further including the step of receiving transmission quality information along with NACK responses, and using the transmission quality information to adjust the number of rateless transmission symbols to initially broadcast according to the monitored NACK rate.

26. The method according to claim 19, further including the step of using the NACK rate to adjust the transmission scheme for broadcasting a next initial set of rateless transmission symbols.

27. The method according to claim 19, further including the step of using the NACK rate to switch some of the mobile devices to a unicast mode, so that the switched mobile devices use a unicast mode to receive a next initial set of rateless transmission symbols.

28. The method according to claim 19, further including the step of using the NACK rate to allocate network resources between broadcast mode and unicast mode.