Cyclic trellis coded modulation

• US 20050254606A1
• Filed: 03/22/2005
• Published: 11/17/2005
• Est. Priority Date: 11/23/1994
• Status: Active Grant

• Current Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Original Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Inventors: Alamouti, Siavash M.
• Granted Patent: US 8,037,396 B2
• Time in Patent Office: Days
• US Class Current: 375/341
• CPC Class Codes: H03M 13/235 Encoding of convolutional codes, e.g. methods or arrangements for parallel or block-wise encoding
• CPC Class Codes: H03M 13/253 with concatenated codes
• CPC Class Codes: H03M 13/256 with trellis coding, e.g. with convolutional codes and TCM
• CPC Class Codes: H03M 13/2936 comprising an outer Reed-Solomon code and an inner convolutional code
• CPC Class Codes: H03M 13/356 Unequal error protection [UEP]
• CPC Class Codes: H03M 13/6538 ATSC VBS systems
• CPC Class Codes: H04L 1/006 Trellis-coded modulation

Abstract

A universal method of trellis encoding signals mapped according to any signal constellation format involves constructing an encoder output table and a state transition table. The encoder output table defines the output symbol of an encoder given the input symbol and the present state of the encoder, while the state transition table defines the next state of the encoder given the present state of the encoder and the input applied to the encoder. The output table and the next state table are constructed with the objective of providing maximal distances between the branches of the trellis diagram without any regards for the shift register implementation of the code. Cyclic trellis coded modulation is an example of such codes without feed-forward or feed-back shift register implementations, and with equal or better performance than “optimal” shift register trellis codes with 16 states or less. The cyclic trellis codes for both AWGN and Rayleigh fading applications can be constructed for any signal constellation without resorting to exhaustive searches.

Claims

1-2. -2. (canceled)

3. An apparatus, comprising:

a trellis encoder for encoding digital signals, wherein the trellis encoder is configured as a state machine or a look-up table memory or in software, but not as a shift register.

4. The apparatus of claim 3, wherein the trellis encoder is not implemented as a feed-forward shift register.

5. The apparatus of claim 3, wherein the trellis encoder is not implemented as a feed-back shift register.

6-12. -12. (canceled)

13. A method for encoding data, comprising:

trellis encoding an input signal via a signal constellation having an even number of constellation points, and

providing paths in the trellis, wherein all the paths merging out of a state and into the same state are defined so as to provide maximal or near maximal spacing between outputs on state transition paths for all signal constellations having an even number of constellation points.

14. A wireless data transmitter, comprising:

a data input means for receiving input data;

a state machine encoder means, coupled to the data input means, the state machine encoder means for providing limited state transition paths, wherein the state transition paths are defined to provide a minimum number of two branch state transition paths between states out of all possible state transition paths between the same state; and

a transmitter means coupled to the state machine encoder means.