Low complexity channel decoders

• US 7,243,295 B2
• Filed: 06/12/2001
• Issued: 07/10/2007
• Est. Priority Date: 06/12/2001
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Yellin, Daniel, Rainish, Doron
• Primary Examiner(s): Torres; Joseph D.
• Application Number:
  US09/880,707
• Publication Number:
  US 20020194567A1
• Time in Patent Office: 2,219 Days
• Field of Search: 714/794, 714/795, 714/759
• US Class Current: 714/794
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• CPC Class Codes: H03M 13/299 Turbo codes with short blocks
• CPC Class Codes: H03M 13/3905 Maximum a posteriori probability [MAP] decoding or approximations thereof based on trellis or lattice decoding, e.g. forward-backward algorithm, log-MAP decoding, max-log-MAP decoding
• CPC Class Codes: H03M 13/6502 Reduction of hardware complexity or efficient processing
• CPC Class Codes: H03M 13/6505 Memory efficient implementations
• CPC Class Codes: H03M 13/6577 Representation or format of variables, register sizes or word-lengths and quantization
• CPC Class Codes: H03M 13/6588 Compression or short representation of variables

Abstract

A packet of encoded data is received and decoded using a look-up table that stores information approximating output of an algorithmic decoding process.

Claims

1. A method for decoding channel-encoded date comprising:

(a) receiving encoded symbols;

(b) compressing the encoded symbols to obtain compressed symbols;

(c) decoding the compressed symbols using a first look-up table that stores information approximating output of an algorithmic decoding process to obtain decoded symbols;

(d) arithmetically combining the compressed symbols with the decoded symbols to obtain a first result;

(e) decompressing the first result to obtain a decompressed first result

(f) interleaving the decompressed first result to obtain an interleaved first result;

(g) compressing the interleaved first result to obtain a compressed, interleaved first result;

(h) decoding the compressed, interleaved first result using a second look-up table that stores information approximating output of an algorithmic decoding process to obtain a decoded first result

(i) arithmetically combining the decoded first result with the compressed, interleaved first result to obtain a second result;

(j) decompressing the second result to obtain a decompressed second result; and

(k) de-interleaving the decompressed second result.

2. The method of claim 1 including:

repeating (b) through (k) until a predetermined criterion is satisfied; and

determining information bits corresponding to the encoded symbols received in (a).

3. An apparatus for decoding channel-encoded data comprising:

memory storing a first look-up table with information approximating output of a first algorithmic decoding process and a second look-up table with information approximating output of a second algorithmic decoding process; and

a processor configured to

(a) compress a packet of received encoded symbols to obtain compressed symbols;

(b) decode the compressed symbols using the first look-up table to obtain decoded symbols;

(c) arithmetically combine the compressed symbols with the decoded symbols to obtain a first result;

(d) decompress the first result to obtain a decompressed first result

(e) interleave the decompressed first result to obtain an interleaved first result;

(f) compress the interleaved first result to obtain a compressed, interleaved first result;

(g) decode the compressed, interleaved first result using the second look-up table to obtain a decoded first result;

(h) arithmetically combine the decoded first result with the compressed, interleaved first result to obtain a second result;

(i) decompress the second result to obtain a decompressed second result; and

(j) de-interleave the decompressed second result.

4. The apparatus of claim 3 wherein the processor is configured to:

repeat (a) through (j) until a predetermined criterion is satisfied; and

determine information bits corresponding to the encoded symbols.

5. An article comprising a computer-readable medium that stores computer-executable instructions for causing a computer system, in response to receiving a channel-encoded data packet, to:

(a) compress a packet of received encoded symbols to obtain compressed symbols;

(b) decode the compressed symbols using a first look-up table approximating output of an algorithmic decoding process to obtain decoded symbols;

(c) arithmetically combine the compressed symbols with the decoded symbols to obtain a first result;

(d) decompress the first result to obtain a decompressed first result

(e) interleave the decompressed first result to obtain an interleaved first result;

(f) compress the interleaved first result to obtain a compressed, interleaved first result;

(g) decode the compressed, interleaved first result using a second look-up table approximating output of an algorithmic decoding process to obtain a decoded first result;

(h) arithmetically combine the decoded first result with the compressed, interleaved first result to obtain a second result;

(i) decompress the second result; and

(j) de-interleave the decompressed second result.

6. The article of claim 5 including instructions for causing the computer system to:

repeat (a) through (j) until a predetermined criterion is satisfied; and

determine information bits corresponding to the encoded symbols.

7. The article of claim 5 including instructions for causing the computer system to decode the compressed symbols using a first look-up table approximating output of a soft-input soft-output algorithmic decoding process, a soft-input hard-output algorithmic decoding process, a hard-input soft-output algorithmic decoding process, or a hard-input hard-output algorithmic decoding process.