| f central interest in this dissertation are algorithms, signals, and circuit structures appropriate for use within the receivers of spread spectrum communication systems. In general, tasks that a spread spectrum receiver must perform include channel estimation, timing and frequency alignment for proper demodulation, and despreading of the received wideband waveform.;Pertaining to the task of channel estimation, the problem of obtaining accurate parameter estimates in a Doppler multipath environment is considered. Through analysis and simulations, it is shown that deconvolution algorithms designed for multipath parameter estimation in the absence of Doppler may also be profitably applied to a Doppler multipath environment. Thus employed, these deconvolution procedures are able to produce estimates of the Doppler channel parameters with much finer resolution than correlation methods.;Before channel estimation or demodulation can occur, the receiver must first know or acquire the precise carrier frequency of the transmitted waveform. The correlation-based receivers that are used within spread spectrum systems are sensitive to small mismatches between the local oscillator frequencies of the transmitter and receiver. Algorithm and signal design issues associated with this problem are discussed, and simulation results are given for a new algorithm which yields a dramatic decrease in the time needed by a spread spectrum receiver to acquire the carrier frequency of the received signal.;A parallel matched filter is central to the operation of an asynchronous spread spectrum receiver and permits reduced search and acquisition times in synchronous systems. The matched filter is often required to perform tens of billions of multiply-add operations per second. This enormous computational load tends to translate into a circuit that can quickly drain the power source of a portable spread spectrum receiver. In this dissertation, a methodology is discussed for implementing low-power matched filters. Both analog and digital circuits are considered, with power consumption being used as the primary metric of comparison. This methodology is applied to the physical implementation of an integrated circuit matched filter built in a 1.2... |
