Method and system for communicating content on a broadcast services communication system

• US 7,020,109 B2
• Filed: 08/21/2002
• Issued: 03/28/2006
• Est. Priority Date: 08/21/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Malladi, Durga P., Grilli, Francesco
• Primary Examiner(s): Patel, Ajit
• Assistant Examiner(s): SHAH, CHIRAG G
• Application Number:
  US10/226,058
• Publication Number:
  US 20040037245A1
• Time in Patent Office: 1,315 Days
• Field of Search: 370/331, 370/338, 370/401, 370/400, 370/352, 370/329, 370/389, 455/432.1, 455/433, 455/435.1, 455/436, 455/437, 455/439, 455/442
• US Class Current: 370/331
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04W 36/0007 for multicast or broadcast services, e.g. MBMS multicast or broadcast application services H04W4/06; resource management for broadcast services H04W72/30; connection management for selective distribution or broadcast H04W76/40
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services

Abstract

An outer decoder and an inner decoder encode a block of information to be transmitted, to improve protection by adding redundancy. The redundancy permits decoding of the information from less than a complete encoded block of information. Time re-alignment of two transmissions of the same content from two base stations can mitigate the problem of clipped frames. The user of the subscriber station can experience seamless service without loss of content, even when handing over to a new cell while receiving a buffer of broadcast content.

Claims

1. A method of receiving content on a broadcast channel by a subscriber station, the method comprising:

receiving a first set of frames of a first transmit buffer transmitted on the broadcast channel from a first cell, wherein the first set of frames contains a first portion of the content, and each frame of the first set of frames has been inner coded and outer coded;

performing a handoff from the first cell to a second cell;

receiving a second set of frames of a second transmit buffer transmitted on the broadcast channel from the second cell, wherein the second set of frames contain a second portion of the content, and each frame of the second set of frames has been inner coded and outer coded in the same manner as the first set of frames;

receiving an indication of the time-alignment of the first set of frames and the second set of frames; and

determining clipped frames of the received first set of frames and the received second set of frames according to the indication of the time-alignment of the first set of frames and the second set of frames.

2. The method of claim 1, wherein receiving the indication of the dyne-alignment of the first set of frames and the second set of frames comprises receiving an indication of the beginning of the transmission of a first frame of the second transmit buffer transmitted on the broadcast channel from the second cell.

3. The method of claim 2, wherein the indication of the beginning of the transmission of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises a system frame number transmitted on a broadcast control channel from the second cell.

4. The method of claim 2 wherein the indication of the transmission of the beginning of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises system time of the second cell transmitted on a broadcast control channel of the second cell.

5. The method of claim 1 further comprising:

inner decoding the received first set of frames and the received second set of frames;

identifying the determined clipped frames as erasure frames; and

outer decoding the received first set of frames and the received second set of frames to correct the erasure frames.

6. The method of claim 5 further comprising:

determining duplicated frames of the received first set of frames and the received second set of frames according to the indication of the time-alignment of the first set of frames and the second set of frames;

determining if any one of the determined duplicated frames has been correctly inner decoded;

when any one of the determined duplicated frames, has been correctly inner decoded, choosing a one of the correctly inner decoded duplicated frames for outer decoding; and

when none of the determined duplicated frames has been correctly inner decoded, identifying the duplicate frames as an erasure frame.

7. A subscriber station for receiving content on a broadcast channel transmitted by a first cell and a second cell, the apparatus comprising:

a radio unit configured to receive a first set of frames of a first transmit buffer transmitted on the broadcast channel from a first cell, wherein the first set of frames contains a first portion of the content, and each frame of the first set of frames has been inner coded and outer coded;

a handoff unit configured to perform a handoff from the first cell to a second cell;

the radio unit further configured to receive a second set of frames of a second transmit buffer transmitted on the broadcast channel an indication of the time-alignment of the first set of frames and the second set of frames from the second cell, wherein the second set of frames contain a second portion of the content, and each frame of the second set of frames has been inner coded and outer coded in the same manner as the first set of frames; and

a processing unit for determining clipped frames of the received first set of frames and the received second set of frames according to the indication of the time-alignment of the first set of frames and the second set of frames.

8. The subscriber station of claim 7, wherein the indication of the time-alignment of the first set of frames and the second set of frames comprises an indication of the beginning of the transmission of a first frame of the second transmit buffer transmitted on a broadcast channel from the second cell.

9. The subscriber station of claim 7, wherein the indication of the beginning of the transmission of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises a system frame number transmitted on a broadcast control channel from the second cell.

10. The subscriber station of claim 8, wherein the indication of the transmission of the beginning of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises system time of the second cell transmitted on a broadcast control channel from the second cell.

11. The subscriber station of claim 7, wherein the processing unit is further configured to inner decode the received first set of frames and the received second set of frames, identify the determined clipped frames as erasure frames, and outer decode the received first set of frames and the received second set of frames to correct the erasure frames.

12. The subscriber station of claim 11, wherein the subscriber station is further configured to determine duplicated frames of the received first set of frames and the received second set of frames according to the indication of the time-alignment of the first set of frames and the second set of frames, and determine if any one of the determined duplicated frames has been correctly inner decoded, choose a one of the correctly inner decoded duplicated frames for outer decoding when any one of the determined duplicated frames has been correctly inner decoded, and identify the duplicate frames as an erasure frame when none of the determined duplicated frames has been correctly inner decoded.

13. An apparatus for receiving content on a broadcast channel transmitted by a first cell and a second cell, the apparatus comprising:

means for receiving a first set of frames of a first transmit buffer transmitted on the broadcast channel from a first cell, wherein the first set of frames contains a first portion of the content, and each frame of the first set of frames has been inner coded and outer coded;

means for performing a handoff from the first cell to a second cell;

means for receiving a second set of frames of a second transmit buffer transmitted on the broadcast channel from the second cell, wherein the second set of frames contain a second portion of the content, and each frame of the second set of frames has been inner coded and outer coded in the same manner as the first set of frames;

means for receiving an indication of the time-alignment of the first set of frames and the second set of frames; and

means for determining clipped frames of the received first set of frames and the received second set of frames according to the indication of the time-alignment of the first set of frames and the second set of frames.

14. The apparatus of claim 13, wherein means for receiving the indication of the time-alignment of the first set of frames and the second set of frames comprises means for receiving an indication of the beginning of the transmission of a first frame of the second transmit buffer transmitted on a broadcast channel from the second cell.

15. The apparatus of claim 14, wherein the indication of the beginning of the transmission of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises a system frame number transmitted on a broadcast control channel from the second cell.

16. The apparatus of claim 14 wherein the indication of the transmission of the beginning of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises system time of the second cell transmitted on a broadcast control channel from the second cell.

17. The apparatus of claim 13 further comprising:

means for inner decoding the received first set of frames and the received second set of frames;

means for identifying the determined clipped frames as erasure frames; and

means for outer decoding the received first set of frames and the received second set of frames to correct the erasure frames.

18. The apparatus of claim 17 further comprising:

means for determining duplicated frames of the received first set of frames and the received second set of frames according to the indication of the time-alignment of the first set of frames and the second set of frames;

means for determining if any one of the determined duplicated frames has been correctly inner decoded;

means for choosing a one of the correctly inner decoded duplicated frames for outer decoding when any one of the determined duplicated frames has been correctly inner decoded; and

means for identifying the duplicate frames as an erasure frame when none of the determined duplicated frames have been correctly inner decoded.

19. A system for communicating content on a broadcast channel, the system comprising:

a first base station comprising a first transmit buffer configured to store a first plurality of inner-coded and outer-coded frames containing a content, wherein a first set of inner-coded and outer-coded frames of the first plurality of inner-coded and outer-coded frames contains a first portion of the content, and the first base station is configured to transmit the first plurality of inner-coded and outer-coded frames on the broadcast channel;

a second base station comprising a second transmit buffer configured to store a second plurality of inner-coded and outer-coded frames containing the content, wherein a second set inner-coded and outer-coded frames of the second plurality of inner-coded and outer-coded frames contains a second portion of the content, and the second base station is configured to transmit the second plurality of inner-coded and outer-coded frames on the broadcast channel and an indication of the time-alignment of transmission of the first plurality of innercoded and outer-coded frames and the second plurality of inner-coded and outer-coded frames; and

a subscriber station configured to receive the first set of the inner-coded and outer-coded frames transmitted from the first base station, to perform a handoff from the first base station to a second base station, and to receive the second set of the inner-coded and outer-coded frames and the indication of the time-alignment of transmission of the first plurality of inner-coded and outer-coded frames and the second plurality of inner-coded and outer-coded frames transmitted from the second base station, and to determine clipped frames of the content according to the indication of the time-alignment of transmission of the first plurality of inner-coded and outer-coded frames and the second plurality of inner-coded and outer-coded frames.

20. The system of claim 19, wherein the indication of the time-alignment of transmission of the first plurality of inner-coded and outer-coded frames and the second plurality of inner-coded and outer-coded frames comprises an indication of the beginning of the transmission of a first frame of the second plurality of inner-coded and outer-coded frames transmitted on the broadcast channel from the second base station.

21. The system of claim 20, wherein the indication of the beginning of the transmission of the first frame of the second plurality of inner-coded and outer-coded frames transmitted on the broadcast channel of the second base station comprises a system frame number transmitted on a broadcast control channel from the second base station.

22. The system of claim 20 wherein the indication of the transmission of the beginning of the first frame of the second transmit buffer transmitted on the broadcast channel of the second cell comprises system time of the second cell transmitted on a broadcast control channel from the second base station.

23. The system of claim 19, wherein the subscriber station is further configured to inner decode the received first set of inner-coded and outer-coded frames and the received second set of inner-coded and outer-coded frames, identify the determined clipped frames as erasure frames, and outer decode the received first set of inner-coded and outer-coded frames and the received second set of inner-coded and outer-coded frames to correct the erasure frames.

24. The system of claim 23, wherein the subscriber station is further configured to determine duplicated frames of the received first set of inner-coded and outer-coded frames and the received second set of inner-coded and outer-coded frames according to the indication of the time-alignment of transmission of the first plurality of inner-coded and outer-coded frames and the second plurality of inner-coded and outer-coded frames, determine if any one of the determined duplicated frames has been correctly inner decoded, when any one of the determined duplicated frames have been correctly inner decoded, choose a one of the correctly inner decoded duplicated frames for outer decoding, and when none of the determined duplicated frames has been correctly inner decoded, identify the duplicate frames as an erasure frame.