Signal Design for High Data Rate DS-UWB Transmissions in MIMO Channels

This paper proposes to employ truncated Nyquist pulses for high data rate DS-UWB transmissions. Experiments conducted in a UWB test-bed have shown that either base-band or modulated raised-cosine pulses with a main lobe duration of 1 nanosec are possible to implement, to transmit and to receive with a digital front-end, besides that those satisfy the FCC UWB signal definition. Additionally, the novel UWB antenna design does not introduce derivative effects on the transmitted and received pulse waveform. By employing a linear filter and sampling at least to the Nyquist rate, near optimal sufficient statistics for detection, decoding and synchronization are created. Moreover, those sufficient statistics allow treating the received DS-UWB signals as vectors in a signal space. Based on this mathematical framework, an iterative receiver that performs joint turbo equalization and decoding for linear space-time coded DS-UWB transmissions in MIMO channels is proposed. By using multiple antennas at the receiver and the turbo principle, the iterative decoding detection algorithm reduces jointly the ISI and self-MAI (produce by the scrambling sequences across the transmit antennas) converging to the matched filter bound. Thus, a good trade-off between complexity and performance of high data rate DS-UWB transmissions (chip rate 2 Gcps) in UWB channels can be achieved. A union bound on the average error rate based on the multivariate weight enumeration function is provided