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Abstract:
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The continuous phase modulation (CPM ) has a constant envelope and compact output power spectrum that makes it a promising underlying technology for power and spectrum efficient broadband wireless communications . However , high implementation complexity (especially the complexity of the receiver ) required to deal with the phase memory and inter -symbol interference has impeded its adoption for broadband wireless communications , and only a few simple CPM modulation schemes have mainly been used , e .g . binary MSK and GMSK . Thus , research on efficient CPM transceivers to reduce the computational and hardware complexity is important . The major contribution of this dissertation is the development of novel frequency domain processing techniques and transceiver strategies to improve power and spectral efficiency , and reduce the complexity of CPM modulation schemes . First , this dissertation presents simplified frequency domain receiver structures and decoding schemes in the frequency domain for binary and M -ary CPM block transmission . The frequency domain receivers utilize parallel and serial structures with frequency domain processing which considerably reduces hardware and computational complexity compared to conventional time -domain processing . In addition , the decoding schemes in the frequency domain eliminate the controlled phase memory through frequency domain phase equalization instead of maximum -likelihood sequential decoders , e .g . Viterbi decoders . Second , frequency domain channel estimation schemes for CPM block transmission are presented , which adopt superimposed training signals to achieve bandwidth and power efficiency while reducing the complexity . In these schemes , the proposed frequency domain channel estimation uses the superimposed training signals as a reference signal to reduce the throughput loss caused by conventionally multiplexed training signals . Superimposed training signal design is presented , and the trade -off between bandwidth efficiency and power efficiency is also analyzed . Third , block transmission schemes and frequency domain equalization methods for CPM are proposed , which consider linear processing instead of conventional decomposition -based processing . The schemes of frequency domain linear processing avoid the complexity overhead (both in computation and hardware ) of conventional orthogonal - or Laurent decomposed -based equalizers . Finally , this dissertation extends CPM block transmission and frequency domain equalization to phase -coded (time -varying modulation index ) CPM , which shows better error performance and bandwidth efficiency than fixed modulation index CPM's . |