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Title: An adaptive receiver for a digital radio-telephone network
Author: Chitamu, Peter Jonas Joseph
ISNI:       0000 0001 3545 1299
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1996
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This thesis is part of the study, design and prototype implementation of a low cost capacity automatic digital radio-telephone Network (RTN) for rural communications and is primarily concerned with the study and investigation of the physical layer aspects of the RTN namely demodulation and radio propagation. We investigate demodulation schemes possible for PI/4 DQPSK modulation and compare them based on hardware requirements and performance degradation due to bandlimiting, frequency uncertainty, and timing uncertainty. We also consider receiver operation in both Additive White Gaussain Noise (AWGN) and in multipath channels in order to recommend a suitable demodulation and equalisation scheme for RTN. This study first shows that in AWGN the Limiter Discriminator Integrator Detector (LDID) using a standard FM receiver and a simple moving averager is a cost effective solution. However, in time dispersive channels the LDID requires equalisation at IF which has hardware implications unless the LDID is operated at a high signal-to-noise ratio of atleast 15dB Eb/N₀. The study thus recommends PI/4 DQPSK non-coherent differential detection with baseband equalisation in hilly areas. Due to the RTN protocol requirements, a fast time delay and complex channel impulse response (CCIR) estimation along with a low complexity equalisation technique is required. We demonstrate a simple but very effective equalisation strategy. A novel equaliser filter taps strategy is presented in this thesis. The channel estimate gives an indication of the computational load requirement for the equalisation. Then, even for channels with precursors down 15dB, the equaliser filter taps are derived from the channel estimate by truncating the impulse response of the inverse channel.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Mobile radio; Wireless networks