SYSTEMS AND METHODS FOR PROTECTING DSL SYSTEMS AGAINST IMPULSE NOISE

• US 20090249133A1
• Filed: 03/26/2009
• Published: 10/01/2009
• Est. Priority Date: 03/26/2008
• Status: Active Grant

• Current Assignee: Ikanos Communications Incorporated (Qualcomm, Inc.)
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Pons, Julien D., Sorbara, Massimo, Duvaut, Patrick, Lambi, Ravindra M.
• Granted Patent: US 8,555,149 B2
• Time in Patent Office: Days
• US Class Current: 714/701
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence
• CPC Class Codes: H03M 13/6533 ITU 992.X [ADSL]
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/1835 Buffer management
• CPC Class Codes: H04L 1/1838 for semi-reliable protocols, e.g. for less sensitive applications such as streaming video buffer level management for video bitstream receiver H04N21/44004
• CPC Class Codes: H04L 1/1858 Transmission or retransmission of more than one copy of acknowledgement message

Abstract

Systems and methods for protecting DSL systems against impulse noise are provided. Disclosed herein are example embodiments of a retransmission technique located above the gamma interface (i.e., in the network processing layer). Such a retransmission technique can be combined with standard RS coding with standard erasure-decoding & triangular interleaving at the PMS-TC layer. Example embodiments of the technique involve using the RS code to protect against REIN noise, and using γ-layer retransmission for protecting against error events not corrected by the RS code, e.g. a SHINE noise in the presence of REIN. Both techniques are used jointly in the case of combined REIN and SHINE noise.

Claims

1. A protection apparatus in an xDSL system for mitigating the effects of repetitive electrical impulse noise (REIN) and a single high impulse noise event (SHINE) within a physical layer and network processing layer, comprising:

a forward error correction (FEC) module, wherein the FEC module comprises;

a Reed-Solomon (RS) encoder-decoder; and

an interleaver-deinterleaver; and

a retransmission module configured to request retransmission of corrupted data fragments within the data stream not corrected by the FEC module.

2. The protection apparatus of claim 1,

wherein the FEC module is configured to mitigate the effects of a first noise source (noise 1) with characteristics INP^noise1 and IA_min^noise1, where INP^noise1 is an impulse noise protection value for noise 1, IA_min^noise1 is a minimum inter-arrival time associated with noise 1;

and

wherein the retransmission module is configured to mitigate the effects of a second noise source (noise

     2) with characteristics INP^noise2 and IA_min^noise2, where INP^noise2 is an impulse noise protection value for noise 2, IA_min^noise2 is minimum inter-arrival time associated with noise 2.

3. The protection apparatus of claim 1, wherein retransmission is performed above a gamma layer of the xDSL system.

4. A method, comprising:

classifying a plurality of packets as retransmit eligible or non-transmit eligible;

queuing packets classified as retransmit eligible in a retransmit queue;

receiving a retransmit request and performing one of;

sending a retransmit response if the received retransmit request is for packets classified as retransmit eligible; and

sending a retransmit denial if the received retransmit request is for packets classified as non-transmit eligible or is for packets not present in the retransmit queue.

5. The method of claim 4, further comprising arranging packets into fragments and appending a retransmission header.

6. The method of claim 5, further comprising performing erasure decoding to improve Return Control Channel (RCC) message protection on a back channel.

7. The method of claim 4, wherein eligibility for retransmission is based on the Quality of Service (QoS).

8. A method, comprising:

storing received packet data fragments in a receiver queue;

determining whether the received packet data fragments belong to a protected channel or an unprotected channel based on whether a lower processing layer supports multiple channels;

sending retransmission requests based on the presence of one or more of the following;

missing sequence identification (SID) numbers; and

corrupted packets, wherein corrupted packets are determined based on a cyclic redundancy check (CRC); and

sending more than one retransmission request if a response is not received within a predetermined roundtrip time.

9. The method of claim 8, further comprising generating a timeout request if a response is not received within a predetermined number of retransmission requests being sent.

10. The method of claim 8, further comprising receiving request denial packets in response to requesting retransmission requests.

11. The method of claim 8, wherein sending retransmission requests is performed by either piggy-backing the retransmission requests onto existing outgoing packets or by sending independent requests.

12. The method of claim 8, further comprising utilizing erasure decoding.

13. The method of claim 8, further comprising storing the retransmit-eligible packets in a receiver queue comprising one of:

an outlet shaper configured to smooth out delay;

a rescheduling queue configured to release packets once they are completely reassembled; and

a pass-thru buffer.

14. The method of claim 8, further comprising receiving retransmitted packets at the receiver, wherein the receiver is configured to request retransmissions one or more times.

15. A protection module in an xDSL system configured to mitigate the effects of noise, comprising:

a forward error correction (FEC) module comprising a Reed-Solomon (RS) encoder-decoder and an interleaver-deinterleaver; and

a retransmission module configured to provide retransmission of corrupted data fragments within the data stream, wherein the FEC module mitigates a first noise and the retransmission module mitigates a second noise.

16. The protection module of claim 15, wherein the first noise and second noise are characterized based on impulse noise protection value and minimum inter-arrival time.

17. The protection module of claim 15, wherein the FEC module is further configured to perform erasure decoding.

18. The protection module of claim 15, wherein the retransmission module performs retransmission above a gamma layer based on a retransmission protocol that supports a plurality of retransmission requests for data eligible for retransmission.

19. The protection module of claim 18, wherein the retransmission protocol further supports retransmission requests for missing sequence identification (SID) numbers and corrupted packets, wherein corrupted packets are determined based on a cyclic redundancy check (CRC).

20. The protection module of claim 18, wherein data is determined to be eligible for retransmission based on corresponding quality-of-service (QoS) requirements.

21. The protection module of claim 15, wherein retransmitted data comprises a time stamp field utilized to manage insertion of retransmitted packets in an outlet shaper buffer to preserve differential delay requirements of an Ethernet bonding protocol.