Improving QoS with MIMO-OFDM in future broadband wireless networks

Abstract

Designing very high speed wireless links that offer good quality-of-service (QoS) and range- capability in non-line-of-sight (NLOS) environments constitutes a significant research and engineering challenge. In this article, we provide an analytical overview and performance analysis, on the key issues of an emerging technology known as Multiple-Input Multiple-Output (MIMO) - Orthogonal Frequency Division Multiplexing (OFDM) wireless that offer significant promise in achieving high data rates over wireless links. MIMO technology holds the potential to drastically improve the spectral efficiency and link reliability in future wireless networks while the OFDM transmission scheme turns the frequency-selective channel into a set of parallel flat fading channels, which is an attractive way of coping with Inter-Symbol-Interference (ISI). The combination of MIMO and OFDM has been designed to improve the data rate and the QoS of the wireless system by exploiting the multiplexing gain and/ or the diversity gain which is a major problem in communication. In this article, key areas in OFDM-MIMO like Space-time block-coding (STBC), channel modeling and channel estimation are presented. Inter-channel-interference (ICI) which causes channel degradation is analyzed and we conclude by highlighting areas of further research.