TABLE OF CONTENTS Space-time block codes (STBCs) have considerably evolved over the years. While they originally attracted much attention thanks to their low decoding complexity, they have been the object of a renewed interest at the light of the diversity-multiplexing trade-off.
STBCs can be seen as a mapping of Q symbols (complex or real) onto a codeword C of size n t T. Those codewords are uncoded in the sense that no error correcting code is contained in the STBC. Theoretically, STBCs may take several forms, but practically, linear STBCs are by far the most widely used. The idea behind linear STBCs is to spread information symbols in space and time in order to improve either the diversity gain, or the spatial multiplexing rate, or both the diversity gain and the spatial multiplexing rate. By packing more symbols into a given codeword, i.e. by increasing Q, the data rate is increased. In the following, we first present a general framework of linear STBCs together with some general properties, before particularizing this framework to some important subclasses of STBCs.
We assume that the channel is constant over the duration of the STBC codeword T. Over such duration, we may drop the subscript k in H k and simply denote the channel matrix as H. Bear in mind that in practice, STBCs are always concatenated with outer coding in order to improve error correcting capabilities and to mitigate the noise. Even...
