L2-Orthogonal ST-code design for multi-h CPM with fast decoding

Continuous phase modulation (CPM) has gained increasing attention due to its favorable trade-off between power and bandwidth efficiency. Multi-h CPM appeared as a generalization of single-h schemes so as to decrease further the need for bandwidth expansion over the wireless channel. Despite the interesting characteristics of CPM, the decoding of the received signal is particularly difficult in a multi-path wireless environment with no diversity. To provide some level of diversity, several authors have proposed to combine CPM with Space-Time Block Coding (STBC). A new family of codes for CPM, based on L²-orthogonality was recently introduced in [8]. These full rate codes achieve full diversity and a low decoding complexity. In this paper, we detail a non trivial extension of these L²-orthogonal Space-Time codes using multi-h signaling schemes. These new codes achieve full diversity and a better spectral compactness by utilizing the available communication bandwidth more efficiently. Also, the decoding complexity is greatly decreased by using only one correlation filter bank for the detection of all transmitted signals.