| Ultra Wide-Band (UWB) systems are considered good candidates for future short range, high throughput wireless communications. This thesis focuses on developments in Impulse UWB, as it promises less complexity and lower power consumption than the competing Orthogonal Frequency Division Multiplexing (OFDM) approach. This work considers different modulation techniques and schemes for impulse UWB, comparing their immunity to noise, efficiency and bit error rate (BER). Then a composite modulation scheme is proposed which is a combination of pulse position modulation and bi-phase modulation: its performance is simulated.; The thesis considers demodulation of the composite waveform, using one template to recover the position, and another to recover the phase. The proposed modulation scheme yields double data throughput, as each symbol presents two bits instead of one, as well as lower BER performance compared to the 2-ary PPM, but a higher BER performance compared to BPM. This scheme will help address the rising application challenges of this promising upcoming technology. This composite modulation scheme improves the BER of the 2-ary PPM through using BPM, resulting in lower BER than 4-ary PPM with the same throughput. Nevertheless; this composite modulation scheme can be used with higher order PPM. The data throughput was calculated for a given Eb/No, and a given distance; the throughput is double than that of 2-ary PPM and BPM. For a BER of 10-2, the proposed scheme requires around 1 dB lower Eb/No than 4-ary PPM. |
