Channel Capacity and Channel Estimation of OFDM Ultra-Wide-Band Systems

Ultra-wide-band (UWB) wireless systems are often applied to short-range high-speed data transmission. According to Shannon formula, UWB system with gigahertz band can reach ultra-high data transmission rate. The Shannon capacity of a communication channel is the maximum transmission rate that the channel can support, and it increases with higher signal to noise power ratio (SNR) and wider bandwidth. However, as widening bandwidths often lead to higher noise power, it is SNR rather than the bandwidth that plays the key role in setting the actual data transmission capacity of a channel. With a significant potential of enhancing SNR, multi-band orthogonal frequency-division multiplexing ultra-wide-band (MB-OFDM UWB) system is able to achieve much higher anti-noise capability and flexibility than the conventional impulse radio (IR) UWB. MB-OFDM UWB with multiple-input multiple-output (MIMO) antennas is a viable way to improve channel capacity and expand coverage area. Simulations show that larger quantity of receiver antenna can improve channel capacity even when the total number of transmitter and receiver antenna is constant. A channel estimation algorithm in MIMO-OFDM technology also can be applied to UWB communications. Simulation shows MB-OFDM UWB systems with MIMO technology can achieve better bit error rate performance than the MB-OFDM UWB systems with single transmitter and receiver antenna.