Performance Analysis of Multi-user Mimo Systems With Sphere Decoder by Pallvi Chawla

Abstract

Multiple-input, multiple-output (MIMO) systems are the most promising technique in wireless communication systems, because of their improvement in terms of performance and bandwidth efficiency. The major advantages of MIMO systems are to increase system reliability through diversity and to achieve higher data rates through spatial multiplexing. MIMO techniques were first investigated for single-user scenario and now it is extended to multi-user MIMO (MU-MIMO) systems. Now days, the important research topic is the study of multi-user MIMO (MU-MIMO) systems. MU-MIMO systems are a key technology for future wireless communication systems because these systems satisfy most of the requirements of the next generations. Such systems have the potential to combine the high throughput achievable with MIMO processing with the benefits of space division multiple access (SDMA). Joint processing of MIMO channels yields maximum diversity regardless of the level of multi-user interference. In this thesis, dirty paper coding (DPC) and various decoding schemes are discussed where there is no limit of transmitting antennas, receiving antennas and users. I have introduced linear and non-linear MU-MIMO processing (decoding) techniques. Linear equalizers are zero forcing (ZF) and minimum mean square error (MMSE) while maximum likelihood (ML), sphere decoder (SD) and fixed sphere decoder (FSD) are nonlinear equalizers. The MU-MIMO decoding techniques that are proposed in this thesis are ZF, MMSE, ML and SD. The major focus will be on SD.