Orthogonal block code design for frequency-selective multiple antenna channels

Orthogonal Space-Time Block Codes (OSTBCs) have several de-sirable properties for delay limited communication over a coherent narrowband (mt) fading multiplc antenna channel. In particular. they provide full diversity, and maximum likelihood detection can be achieved via linear processing and symbol-by-symbol detec-tion..As a result, the maximal symbol rate arid minimal latencies of OSTBCs have been well studied. In this paper, we construct orthogonal block codes for frequency-sclective multiple antenna channels. and study their symbol rate and latency properties. Our code construction is based on direct application of the orthogonal-ity constraints. This enables us to show that the maximum symbol rate of an orthogonal block code for a channel with memory length 1, is 1 / L times thc maximum rate of an OSTBC for the same an-tenna confguration. Orthogonal codcs that achieve this maximal rate can be simply constructed via the Kronecker product ofa rate maximal OSTBC with an identity matrix of size L. This Kro-nccker design scheme can also be applicd to construct orthogonal block codes for frequency-selectivc channels with other desirable properties. such as minimal latency. 1