28-02-2011, 02:03 PM
[attachment=9221]
Implementation of parallel Reed-Solomon Turbo Decoder
Objective
Implementing RTL code for RS turbo decoder.
To achieve high efficiency.
To achieve high Throughput
Overview
Implementing RS turbo decoder using VHDL code.
Introduce errors.
Detecting the errors.
Correct the errors.
RS Decoder
Syndrome computation (S C ).
KEY (Key- equation- solver).
CSEE (Chien search Error evaluator ).
Architecture
Pseudo code for RS decoder
1 : Introduce errors fSimulate noiseg
2 : Compute Syndromes
3 : if S(x) = 0 then
4 : Declare no error
5 : else (Error in code word)
6 : {Key Equation Solver}
7 : for all j such that do
8 : if = 0 then {Chien Search}
9 : Compute Yi {Forney Evaluator}
10 : Add Yi to the received symbol.
11 : end if
12 : end for
13 : end if
14 : Compare the output with the original code word
K E S
Generates the key equation
Error locator
Error evaluator
The two polynomial defined as
The syndromes are used to compute the error locator and error evaluator polynomial.
If there are e errors in the received code word, we can define the error locator polynomial of degree e and the error evaluator polynomial of degree at most e − 1 to be
Chien Algorithm
Chien search involved checking whether for each j,
If it is, then an error has occurred at j th location in the received code word.
Error Evaluator
The next step is to compute the value of error, Yi that has occurred.
This is computed by Forney’s error value formula :