Interleaved coding and predetection diversity for hybrid DS/SFH-SSMA over indoor radio channels

The performance is studied of hybrid direct-sequent/slow-frequency-hopped spread-spectrum multiple-access (DS/SFH-SSMA) systems with noncoherent DPSK demodulation, using predetection diversity equal gain combining in conjunction with interleaved channel coding (Hamming (7,4) code and BCH (15,7) code) operating through indoor radio multipath Rayleigh fading channels. Two interleaving techniques are considered. In the first interleaving technique all bits of a codeword are transmitted during the same hop, whereas in the second, each bit of a codeword is transmitted during a different hop. It is shown that, in the absence of multiaccess interference, both interleaving techniques yield the same bit error rate performance. In the presence of multiaccess interference, the second interleaving technique has a performance advantage over the first, and this advantage increases with increasing diversity order and multiaccess interference level