Capacity of Wireless Communication Systems Employing Antenna Arrays, a Tutorial Study

A tutorial study is performed on the capacity of multiple antenna wireless communication systems. Multiple antenna structures can be classified into single-input multiple-outputs (SIMO), multiple-inputs singleoutput (MISO), and multiple-inputs multiple-outputs (MIMO) systems. Assuming that the channel is known at receiver, capacity expressions are provided for each structure, under the conditions of quasi-static flat fading. Also, information rate limits are provided in each case for some suboptimal structures or detection techniques that may be used in practice. Using simulations for the case of flat Rayleigh fading, capacities of optimal/suboptimal implementations are contrasted for each multi-antenna structure. Discussions are made on system design, regarding implementation complexity and practical limitations on achieving these capacities. In particular, the problem of fading correlation and required antenna spacing, effect of fast channel fading, and lack of channel knowledge at receiver are discussed. Providing the results of the most recent researches considering the capacity of multiantenna systems, as well as some new results, this paper can give a good perspective for designing appropriate architectures in different wireless communication applications.