Tail-Biting Convolutional Codes for the Secondary Fast Feedback Channel: Fading Channel Results

Document Number: C802.16m-09/0910 Date Submitted: 2009-04-27

Source: Ericsson AB, Tsao-Tsen (Jason) Chen (jason.t.chen@ericsson.com) Kai Yu

Sten SjöbergPer-Erik Östling

Re: Category: AWD comments / Area: Chapter 15.3.9 (UL-CTRL) “Comments on AWD 15.3.9 UL-CTRL” Venue:

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Tail-biting convolutional codes (TBCC) for Secondary Fast Feedback Channel (SFBCH)

• Performances of TBCC [1] over fading channels are better than or about the same as other linear block codes [2] for SFBCH for payload 7 to 24 bits– 13 to 24 bits: 0.4dB~2.3dB gain @ PER=10-1 ~10-3

– 7 to 12 bits: about the same performances

• TBCC can be decoded efficiently by simple Wrap-Around Viterbi Algorithm (WAVA), with complexity much less than linear codes with MLD or trellis decoding for most payload cases [1]

TBCC w 1 Encoding: one 18-bit payload Linear Code w 2 Encodings: two 9-bit payloads

-6 -4 -2 0 2 4 6 8 10 12 1410

-4

10-3

10-2

10-1

100

EsN0 (dB)

PE

R

payload 18 bits, 1Tx2Rx, VehA 120Km/hr

Intel (30,9)

Samsung (30,9)LGe (30,9)

TBCC (60,18)

TBCC gains over the best of 3 linear codes: payload >12 bits (0.4dB~2.3dB)

ChannelModel

ChannelEstimation

Target PER

Payload 14 bits

Payload 16 bits

Payload 18 bits

Payload 20 bits

Payload 22 bits

Payload 24 bits

PedB-3 pilot avg 10% 0.54 0.54 0.47 0.43 0.42 0.42

VehA-120 pilot avg 10% 0.79 0.70 0.68 0.71 0.69 0.66

VehA-350 Perfect 10% 1.35 1.47 1.31 1.22 1.27 1.18

PedB-3 pilot avg 1% 0.49 0.53 0.50 0.42 0.38 0.43

VehA-120 pilot avg 1% 1.06 1.03 1.04 1.08 1.06 1.12

VehA-350 Perfect 1% 1.83 1.84 1.73 1.67 1.56 1.47

PedB-3 pilot avg 0.1% 0.57 0.45 NA NA NA NA

VehA-120 pilot avg 0.1% 1.66 1.68 1.78 1.96 2.05 2.34

VehA-350 Perfect 0.1% 2.12 2.18 1.99 1.91 1.82 1.76

TBCC losses over the best of 3 linear codes: payload ≤ 12 bits (about the same performances)

ChannelModel

ChannelEstimation

TargetPER

Payload 7 bits

Payload 8 bits

Payload 9 bits

Payload 10 bits

Payload 11 bits

Payload 12 bits

PedB-3 pilot avg 10% 0.09 0.09 0.08 0.06 0.05 0.07

VehA-120 pilot avg 10% 0.08 0.09 0.09 0.06 0.06 0.09

PedB-3 pilot avg 1% 0.07 0.09 0.07 0.04 0.05 0.09

VehA-120 pilot avg 1% 0.07 0.09 0.09 0.05 0.06 0.12

VehA-350 Perfect 1% -0.46 0.18 0.12 0.09 0.08 0.07

PedB-3 pilot avg 0.1% 0.05 0.10 0.08 0.04 0.05 0.12

VehA-120 pilot avg 0.1% 0.09 0.12 0.10 0.06 0.06 0.16

VehA-350 Perfect 0.1% 0.33 0.22 0.13 0.09 0.08 0.07

Conclusion and References

• We recommend that TBCC [1] be used to encode the SFBCH with payload sizes from 7 to 24 bits, with one encoding [1] for all payload cases.

• [1] IEEE C80216m-09_0506r3, “Tail-Biting Convolutional Codes with Expurgation and Rate-Compatible Puncturing for the Secondary Fast Feedback Channel”.

• [2] IEEE C80216m-09_0387, “Proposed Text for the Draft P802.16m Amendment on the PHY structure for UL control – merged version”.

Backup Slides

Simulation Assumptions

Channel Bandwidth 10MHz

FFT Size 1024

Cyclic Prefix Ratio 1/8

Channel Model PedB-3Km/hr, VehA-120Km/hr, VehA-350Km/hr

Antenna Scheme 1Tx2Rx

Modulation QPSK

Channel Estimation Perfect channel estimation and pilot averaging

Tile Structure 3 distributed 2x6 tiles, 2 pilots per tile

Decoder TBCC: Wrap-around Viterbi algorithm with simple termination condition and maximum 4 iterationsLinear codes: MLD

Error Statistics For linear codes with 2 smaller encoded packets per payload (13 bits to 24 bits), the overall packet is declared erroneous if either one of the 2 smaller encoded packets is in error