Sets of rate-compatible universal turbo codes nearly optimized over various rates and interleaver sizes
A method and apparatus for Turbo encoding uses a set of rate-compatible Turbo Codes optimized at high code rates and derived from a universal constituent code. The Turbo Codes have rate-compatible puncturing patterns. The method comprises: encoding a signal at a first and second encoder using a best rate 1/2 constituent code universal with higher code rates, the first encoder and the second encoder each producing a respective plurality of parity bits for each information bit; puncturing the respective plurality of parity bits at each encoder with a higher rate best puncturing patterns; and puncturing the respective plurality of parity bits at each encoder with a lower rate best puncturing pattern. In a variation, the best rate 1/2 constituent code represents a concatenation of polynomials 1+D 2 +D 3 (octal 13 ) and 1+D+D 3 (octal 15 ), D a data bit. A Turbo Encoder is provided which has hardware to implement the method.
1. A method comprising:
encoding a first bit stream using an encoder having a transfer function G(D)=[1, (1+D+D 3 )/(1+D 2 +D 3 )] to produce a second bit stream at a 1/3 coding rate;
reducing the second bit stream to produce a third bit stream having desired coding rate; and
generating a radio signal based on the third bit stream.
2. The method of claim 1 , wherein reducing the second bit stream to produce a third bit stream having desired coding rate comprises providing the third bit stream at a coding rate of 1/2, 3/8, or 4/9.
3. The method of claim 1 , wherein reducing the second bit stream to produce a third bit stream having desired coding rate comprises removing parity bits.
4. The method of claim 1 , wherein reducing the second bit stream to produce a third bit stream having desired coding rate comprises variably puncturing parity bits produced by the encoder to vary a coding rate of the third bit stream.
5. The method of claim 1 , wherein the encoder consists of two constituent encoders having generator polynomials of:
d ( D )=1+ D 2 +D 3 ; and 1)
n ( D )=1+ D+D 3 . 2)
6. A system comprising:
an encoder circuit configured to encode a first bit stream using encoder having a transfer function G(D)=[1, (1+D+D 3 )/(1+D 2 +D 3 )] and providing a second bit stream having a 1/3 coding rate and to reduce the second bit stream to produce a third bit stream with a desired coding rate; and
a radio transmission circuit configured to generate a radio signal based on the third bit stream.
7. The system of claim 6 , wherein the encoder circuit is configured to produce the third bit stream at a coding rate of 1/2, 3/8, or 4/9.
8. The system of claim 6 , wherein the encoder circuit is configured to produce the third bit stream by removing parity bits.
9. The system of claim 6 , wherein the encoder circuit is configured to variably puncture parity bits produced by the encoder to vary a coding rate of the third bit stream.
10. The system of claim 6 , wherein the encoder consists of two constituent encoders having generator polynomials of:
d ( D )=1+ D 2 +D 3 ; and 1)
n ( D )=1+ D+D 3 . 2)