BER performance improvement in MIMO systems using various equalization techniques

Proliferation of mobile data applications has increased the demand for wireless communication systems which offers high throughput, wide coverage, and improved reliability. The main challenges in the design of such systems are the limited resources (like transmission power, scarce frequency bandwidth and limited implementation complexity) and the impairments of the wireless channels which includes noise, interference, and fading effects. Multiple-Input Multiple-Output (MIMO) systems is one of the most promising wireless technologies that can achieve above requirements. Inter-symbol interference (ISI) is still a major concern even in MIMO systems. It degrades the system performance significantly in frequency selective channels. To mitigate ISI, equalization techniques are employed on receiver side. In this paper, Bit error rate (BER) performance improvements of MIMO systems using various equalization techniques like Zero-forcing (ZF), Minimum mean square error (MMSE), ZF-Successive interference cancellation (ZF-SIC), MMSE-SIC, Maximum likelihood (ML) and Sphere decoder (SD) are shown and compared. BER analysis is done under Rayleigh frequency flat and selective as well as under Rician frequency flat channels.