Multi-band UWB system with Hadamard coding

In this paper, a new multi-band ultra wideband (UWB) system with Hadamard coding, namely, MB-H-UWB, is proposed. The ultra-wide bandwidth is divided into M subbands. The sub-bands are then coded with Hadamard codes. In this way, the frequency diversity is obtained. Transmitted data bits are modulated in the corresponding coded sub-bands. Both single and multiple user system are considered in this paper. A random time-hopping sequence is used for the multi-user access. Simulation results show that the proposed MB-H-UWB system can accomplish a 1.7 dB gain of SNR for single-user, and 2.8 dB gain and 4 dB gain for 10 active user and 20 active users, respectively, over a BPSK-UWB system in a AWGN channel with the targeted uncoded bit error rate (BER) of 10^-3. Simulation results also show that the proposed MB-H-UWB system outperforms BPSK-UWB system by 2 dB in an indoor multipath propagation channel. The performance gain of the MB-H-UWB system can benefit range extension and higher throughput for UWB communication systems. Moreover, the proposed system requires less Rake receiver fingers than the single-band (7.5 GHz bandwidth) UWB system so that the complexity of the receiver can be reduced significantly.