Novel tree-search algorithm versus Sphere-Decoding-Based Algorithms for MIMO system with Inter-Symbol Interference

In this paper we firstly propose a general model to combat the Inter-Symbol Interference (ISI) caused by frequency selective channels in a Multi-InputMulti-Output (MIMO) system and/or by asynchronous cooperative transmissions. The general model is not only exemplified by the Asynchronous Cooperative Liner Dispersion Codes (ACLDC) scheme, but also by the Time-Reversed Space-Time Block Code (TR-STBC) scheme. In these schemes a guard interval of various lengths has to be inserted to help mitigate the effect of ISI. Consequently, this could impact the effective symbol rate for a small block-size. A larger block size however, could substantially increase the decoding complexity. We present a novel low-complexity breadth-adjustable tree-search algorithm in the proposed general model. We will discuss the difference between our algorithm and the Sphere Decoding (SD)-based algorithms. With simulation results, we will illustrate that our algorithm will achieve the optimal Bit-Error-Rate (BER) performance with a complexity that is lower than the SD-based algorithms, whether the system employs the ACLDC scheme or the TR-STBC scheme.