MIMO Technology in wireless communications

Digital communication using MIMO (multiple-input multiple-output) or also called volume to volume wireless links is emerging as one of the most promising research areas in wireless communications. In wireless MIMO the transmitting end as well as the receiving end is equipped with multiple antenna elements, as such MIMO can be viewed as an extension of the very popular ‘smart antennas’. In MIMO though the transmit antennas and receive antennas are jointly combined in such a way that the quality (Bit Error Rate) or the rate (Bit/Sec) of the communication is improved. At the system level, careful design of MIMO signal processing and coding algorithms can help increase dramatically capacity and coverage and thus can improve the economics of network deployment for operators. Today, MIMO wireless is widely recognized as one of three or four key technologies in the forthcoming high-speed high-spectrum efficiency wireless networks (4G, and to some extent 3G). Applications also exist in fixed wireless and wireless LAN networks.

Progress in MIMO research poses strong scientific challenges in the areas of modeling (of mobile space-time wireless channels), information theory (coding, channel capacity and other bounds on information transfer rates), signal processing (signaling and modulation design, receiver algorithms), and finally the design of the wireless fixed or mobile networks that will incorporate those MIMO links in order to maximize their gain. More specifically, joint design of sensible multiple access solutions (CDMA, OFDMA, TDMA and variants) as well as medium access (MAC) protocol for wireless MIMO is challenging.