Orthogonal Pulse Based Modulation Schemes for Time Hopping Ultra Wideband Radio Systems

Time hopping ultra wideband (TH-UWB) communication promises to be a viable technique to build a relatively simple, low-cost and 1ow-power transceiver that can be used for short range high speed wireless communication over the multipath channel. The successful deployment of TH-UWB systems strongly depends on the development of pulse waveforms, modulation techniques and system complexity. The TH-UWB message symbols are transmitted by short analog pulse waveforms. Because of the short pulse waveforms, UWB is capable of providing high data rates for short range communication. Various kinds of modulation schemes have been proposed for the purpose of achieving high data rates. But a major challenge is the selection of an appropriate modulation scheme in designing a system. System model, channel model, channel capacity, interference, system performance, spectral characteristics and coexistence capability are all related issues with in the type of modulation employed. It is in this context, dissertation focusses on modulation schemes based on orthogonal pulses such as modified Hermite pulses (MHPs) and Prolate spheroidal wave functions (PSWFs). To achieve cost effective system design, a combined modulation scheme, called on-off keying (OOK) and pulse shape modulation (PSM)(OOK-PSM), for M-ary signaling has been proposed. It provides low power and low cost system by using fewer orthogonal pulses and receiver correlators than those used in PSM and biorthogonal PSM (BPSM) schemes. Various interference issues such as MAl, inter pulse interference (IPI) and multi pulse interference (MPI) are analyzed for the combined OOK-PSM scheme. Despite its several advantages, the proposed OOK-PSM scheme cannot be used for higher level modulation schemes in the presence of multipath channel. To overcome this problem, another combined modulation scheme, using orthogonal pulse position modulation (OPPM) and BPSM (OPPM-BPSM), has been proposed for xvi ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library