Methods for forward error correction coding above a radio link control layer and related apparatus

• US 20050193309A1
• Filed: 08/19/2004
• Published: 09/01/2005
• Est. Priority Date: 08/21/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Casaccia, Lorenzo, Grilli, Francesco, Vayanos, Alkinoos Hector
• Granted Patent: US 8,694,869 B2
• Time in Patent Office: Days
• US Class Current: 714/752
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/2707 Simple row-column interleaver, i.e. pure block interleaving
• CPC Class Codes: H03M 13/2915 with an error detection code in one dimension
• CPC Class Codes: H03M 13/373 with erasure correction and erasure determination, e.g. for packet loss recovery or setting of erasures for the decoding of Reed-Solomon codes
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04W 72/30 Resource management for broadcast services

Abstract

Transmission techniques are provided that improve service continuity and reduce interruptions in delivery of content that can be caused by transitions that occur when the User Equipment (UE) moves from one cell to the other, or when the delivery of content changes from a Point-to-Point (PTP) connection to a Point-to-Multipoint (PTM) connection in the same serving cell, and vice-versa. Such transmission techniques enable seamless delivery of content across cell borders and/or between different transmission schemes such as Point-to-Multipoint (PTM) and Point-to-Point (PTP). Mechanisms for adjusting different streams and for recovering content from each data block during such transitions are also provided so that data is not lost during a transition. In addition, mechanisms for realigning data during decoding at a receiving terminal are also provided.

Claims

1. A system for transmitting information blocks, comprising:

a destination station comprising a decoder;

a first source of a particular content that transmits first outer blocks over a common channel for receipt by the destination station using a first data transfer mode,

wherein the first outer blocks include information blocks and redundancy blocks that can be used to reconstruct the information blocks,

wherein the redundancy blocks are generated above a radio link control layer; and

a second source of the particular content that transmits second outer blocks comprising information blocks over a dedicated channel for receipt by the destination station using a second data transfer mode when the destination station undergoes a transition,

wherein the second outer blocks are time-shifted with respect to the first outer blocks, and

wherein the decoder is configured to reconstruct any information blocks lost during the transition using the redundancy blocks.

2. A system according to claim 1, wherein the transmission rate of the information blocks from the second source of the particular content is greater than the transmission rate of the information blocks from the first source of the particular content, and wherein the second source of the particular content starts transmission at a first information block of the first outer block being transmitted when the transition occurs to thereby reduce loss of information blocks during the transition.

3. A system according to claim 1, wherein the second source of the particular content retransmits a second outer block over the dedicated channel if any information blocks from the second outer block not received correctly during another transition from the second source of the particular content to the first source of the particular content.

4. A system according to claim 1, wherein each block occupies one frame.

5. A system according to claim 1, when the transition occurs while the same outer block is being transmitted from each source, wherein the destination station combines the information blocks received from the first source of the particular content and the information blocks received from the second source to produce the complete outer block.

6. A system according to claim 1, wherein the first source of the particular content includes a Reed-Solomon encoder that encodes the information blocks to generate the redundancy blocks, and adds the redundancy blocks to the information blocks to generate outer code blocks.

7. A system according to claim 1, wherein the outer decoder decodes the first outer code block and reproduces any missing information blocks via said redundancy blocks.

8. A method for receiving content by a destination station, wherein the content comprises a plurality of inner content blocks, the method comprising:

formatting the content as a first outer block comprising the inner content blocks and inner parity blocks based on the inner content blocks;

transmitting the first outer block over a common channel;

receiving at least a portion of the first outer block;

formatting the content as a second outer block comprising the inner content blocks;

transmitting the second outer block over a dedicated channel;

transitioning from transmission of the content over the common channel to transmission of the content over the dedicated channel;

receiving at least a portion of the second outer block, wherein the second outer block is time-shifted with respect to the first outer block; and

using the portion of first outer block received before the transition occurs, along with the portion of the second outer block to generate a complete outer block that comprises the plurality of inner content blocks to thereby compensate for the time-shift between the first outer block and the second outer block.

9. The method of receiving content according to claim 8, when any ones of the inner content blocks transmitted over the common channel are not received correctly, using the inner parity blocks to reconstruct ones of the inner content blocks that are not received correctly.

10. The method of receiving content according to claim 9, wherein each of the inner blocks includes a sequence number comprising an outer block index and an inner block index, and wherein using the portion of first outer block received before the transition occurs, along with the portion of the second outer block to generate a complete outer block that comprises the plurality of inner content blocks to thereby compensate for the time-shift between the first outer block and the second outer block, comprises:

determining a last outer block index and a last inner block index that correspond to the sequence number of a last inner block received over the common channel; and

determining a new outer block index and a new inner block index that correspond to the sequence number of a first inner block received over the dedicated channel.

11. The method of receiving content according to claim 10, wherein if the last outer block index matches the new outer block index, combining the received portion of first outer block with the second outer block beginning at the inner block of the second outer block having the next inner block index following the last inner block index to thereby compensate for the time-shift between the first outer block and the second outer block.

12. The method of receiving content according to claim 11, further comprising:

if the last inner block index is greater than the new inner block index,

discarding the inner blocks of the second outer block up to the inner block of the second outer block having an inner block index equal to the last inner block index to thereby compensate for the time-shift between the first outer block and the second outer block.

13. The method of receiving content according to claim 11, further comprising:

if the last inner block index is less than the new inner block index,

storing the second outer block beginning at the first inner block of the second outer block to thereby compensate for the time-shift between the first outer block and the second outer block.

14. The method of receiving content according to claim 10, wherein the time-shift comprises a difference in time alignment between the first outer block and the second outer block.

15. A method for seamless delivery of broadcast and multicast content to a terminal, comprising:

transmitting a Point-to-Multipoint (PTM) transmission using outer block codes, wherein each outer block code comprises inner data blocks and inner parity blocks;

anticipating, when the terminal transitions from the Point-to-Multipoint (PTM) transmission to a Point-to-Point (PTP) transmission, transmission of outer block codes during the Point-to-Point (PTP) transmission with respect to the Point-to-Multipoint (PTM) transmission by starting the Point-to-Point (PTP) transmission from the beginning of the same outer block code, wherein delivery of a complete outer block code via the Point-to-Point (PTP) transmission on average is faster than via the Point-to-Multipoint (PTM) transmission; and

recovering any delay introduced by the transition via faster delivery of complete outer block codes via the Point-to-Point (PTP) transmission to recover any lost inner blocks and thereby allow for a seamless transitions from the Point-to-Point (PTP) transmission to the Point-to-Multipoint (PTM) transmission.

16. A method according to claim 15, wherein inner parity blocks are not transmitted in the Point-to-Point (PTP) transmission.

17. A method according to claim 16, wherein starting the Point-to-Point (PTP) transmission from the beginning of the same outer block code, comprises:

starting the Point-to-Point (PTP) transmission from the beginning of the first inner block.

18. A method for seamless delivery of broadcast and multicast content to a terminal during a transition across cell borders, comprising:

transmitting a Point-to-Multipoint (PTM) transmission using outer block codes, wherein each outer block code comprises inner data blocks and inner parity blocks;

anticipating, when the terminal transitions across the cell borders, transmission of outer block codes during Point-to-Point (PTP) transmission with respect to the Point-to-Multipoint (PTM) transmission by starting the Point-to-Point (PTP) transmission from the beginning of the same outer block code, wherein delivery of a complete outer block code via the Point-to-Point (PTP) transmission on average is faster than via the Point-to-Multipoint (PTM) transmission; and

recovering any delay introduced by the transition via faster delivery of complete outer block codes via the Point-to-Point (PTP) transmission to recover any lost inner blocks and thereby allow for a seamless transitions from the Point-to-Point (PTP) transmission to the Point-to-Multipoint (PTM) transmission.

19. A method according to claim 18, wherein inner parity blocks are not transmitted in the Point-to-Point (PTP) transmission.

20. A method according to claim 19, wherein starting the Point-to-Point (PTP) transmission from the beginning of the same outer block code, comprises:

starting the Point-to-Point (PTP) transmission from the beginning of the first inner block.