1. Efficient Space-Time Block Codes Designed by a Genetic Algorithm Don Torrieri U.S. Army Research Laboratory Matthew C. Valenti West Virginia University

2. Space-Time Block Codes Orthogonal STBC provides full diversity at full rate and linear ML decoding but exists only for 2 antennas. Some STBCs preserve full diversity and full rate but have more complex decoding. STBC may be evolved to have full rate decoupled decoding at cost of diversity.

3. STBC

4. Generator Matrix

5. MDC-QO (4, 4, 4) STBC

6. Dispersion Matrices

7. Orthogonality Condition

8. Orthogonality Requirements

9. Cost function

10. Genetic Algorithm String of genes specifies the entries of dispersion matrices of particular STBC Parents breed children Genes of child are identical to a parent except at randomly chosen crossover positions, and mutations are generated Selection entails replacement of parent or culling of least fit Cloning and immigration moves genes from one pool to another

11. Parent Selection Random selection Preferred parenting Eugenic selection Alpha-male parenting

12. Cost vs. generation

13. (4, 3, 4) codes & QPSK

14. (6, 3, 6) codes & QPSK

15. SE = 3bits/s/Hz, 3 antennas

16. SE = 3bits/s/Hz, 4 antennas

17. Turbo-coded Performance

18. Conclusions Genetic algorithm produces STBCs optimized for decoupled decoding. When spectral efficiency is specified, outer code is used, and fading is severe, evolved codes outperform orthogonal STBCs. Alpha-male parenting and parallel execution using cloning and immigration expedite evolution.