Duo-Binary Circular Turbo Decoder Based on Border Metric Encoding - - PowerPoint PPT Presentation

▶
duo binary circular turbo decoder based on border metric
SMART_READER_LITE
LIVE PREVIEW

Duo-Binary Circular Turbo Decoder Based on Border Metric Encoding - - PowerPoint PPT Presentation

Mar 04, 2023 134 likes •281 views

Duo-Binary Circular Turbo Decoder Based on Border Metric Encoding for WiMAX for WiMAX Ji-Hoon Kim and In-Cheol Park Division of Electrical Engineering Division of Electrical Engineering KAIST Introduction to Turbo Codes Introduction to Turbo

slide-1
SLIDE 1

Duo-Binary Circular Turbo Decoder Based on Border Metric Encoding for WiMAX for WiMAX

Ji-Hoon Kim and In-Cheol Park Division of Electrical Engineering Division of Electrical Engineering KAIST

slide-2
SLIDE 2

Introduction to Turbo Codes Introduction to Turbo Codes

  • Introduced in 1993

– Error Correcting Performance within 0.5dB of Shannon limit Wid l U d i W CDMA CDMA2000 d WiMAX – Widely Used in W-CDMA, CDMA2000, and WiMAX – Non-Uniform Interleaver – Iterative Decoding Iterative Decoding

SISO RSC Decoder 1 Encoder 1 RSC Interleaver SISO Interleaver

2

Encoder 2 Decoder 2

slide-3
SLIDE 3

Turbo Codes for WiMAX Turbo Codes for WiMAX

  • Double-Binary Turbo Codes

– Better Convergence Larger Minimum Distances

  • Circular Coding

– a.k.a Tail-Biting No Tail Bits – Larger Minimum Distances – Reduced Latency – No Tail Bits – Avoid Spectrum Waste

< CTC Encoder for WiMAX > < 4-State Trellis for Circular Coding >

3

slide-4
SLIDE 4

Max log MAP for Double Binary Max-log-MAP for Double-Binary

7 7

11/00/01/10 Z (Source Bits)

6 5 6 5

01/10/11/00 11/00/01/10

4 4

01/10/11/00

3 2 3 2

00/11/10/01 10/01/00/11

1 1

10/01/00/11

with Minimum Overhead with Minimum Overhead

00/11/10/01

slide-5
SLIDE 5

Sliding Window For Non-Binary Turbo Decoder

Small Window Size, Large Frame Size Huge Border Memory!

  • Border Metric with the values
  • f previous Iteration

Avoid complex dummy calculation

g y

– Avoid complex dummy calculation

Complex Dummy Metric Calculation

Efficient for Efficient for

Dummy Metric Calculation @ Border

Efficient for Efficient for Circular Coding Circular Coding

slide-6
SLIDE 6

Proposed Border Metric Encoding Proposed Border Metric Encoding

  • Allow only a few values for the Border Metric

Flooring the Original Value to the Closest Power-of-Two Number

Encoding Scheme Encoded Values

6

4-bit Encoding ±256, ±128, ±64, ±32, ±16, ±8, ±4, 0 (15 values)

slide-7
SLIDE 7

BER Performance Comparison BER Performance Comparison

  • Almost No Performance Degradation!

7

slide-8
SLIDE 8

Proposed Dedicated Interleaver Proposed Dedicated Interleaver

  • Accumulator-Based Interleaver

– Small Area due to Simple Hardware

8

slide-9
SLIDE 9

Key to Low Power Consumption Key to Low-Power Consumption

  • Small-Sized Border Memory

– By Border Metric Encoding

I f t A t B d M

  • Infrequent Access to Border Memory

– Only one load/store for processing one Window

9

slide-10
SLIDE 10

Implementation Results Implementation Results

  • Time Multiplex Architecture
  • Time-Multiplex Architecture

SISO Algorithm Max-log-MAP (Duo-Binary) Operating Frequency 200 MHz Window Size 32 Gate Count 65k Iteration 8 (Fixed) Data Rate 24.26 Mbps

slide-11
SLIDE 11

Memory Size Comparison Memory Size Comparison

  • Single-Port SRAM Size

– Required for a SISO Decoder 100 % 100.4 % 79.3 % 20.7 %

11

slide-12
SLIDE 12

Energy Consumption Comparison Energy Consumption Comparison

  • For a SISO Decoder @ 1 2dB
  • For a SISO Decoder @ 1.2dB

100 % 73.8 % 26.2 %

12

slide-13
SLIDE 13

Conclusion Conclusion

  • Border Metric Encoding is Proposed

– Avoid Complex Dummy Calculation Eff ti f bi T b C d – Effective for non-binary Turbo Codes

  • Dedicated Hardware Interleaver is Proposed

– Generate Interleaved Addresses on-the-fly

  • CTC Decoder for WiMAX is Designed

g

– Based on ..

  • Border Metric Encoding
  • Dedicated Hardware Interleaver

13