| Summary: | 博士 === 國立臺灣科技大學 === 電子工程系 === 91 === In this thesis, data rate maximization (RM) in multichannel communications is proposed, subject to joint constraints on
available energy budget and tolerable degradation of service (DOS). Two cases are considered. Namely, the communication
is conducted over either AWGN (additive white Gaussian noise) or Rayleigh fading channels. For the AWGN case, each
subchannel is individually exploited to carry a symbol during one symbol duration. For the fading case, grouping of the
subchannels is made to provide diversity for transmitted symbols.
First, we consider the case of AWGN subchannels. Three algorithms are proposed for the RM of transmitted data in
multichannel communications. Altogether referred to as the RM algorithms, they consist of the EADRM, the DADRM, and the
fDADRM algorithms. Closed-form expressions for representing the energy (for EADRM) or DOS (for DADRM and fDADRM) of one subchannel as a function of that of another is derived based on the rate-distortion optimization theory, when the bit allocation is pre-specified. The specification of bit allocations is achieved by the use of the so-called eligible bit allocation matrix (EBAM), which is a function of the total data rate and the number of subchannels. Then, a greedy approach is adopted to raise the total data rate until the relevant constraints can no longer be satisfied. While all three RM algorithms essentially generate identical maximum data rates, the fDADRM algorithm is much faster than the others in computation. As compared to the result achievable by a
single-channel communication scheme, the RM algorithms produce a much higher data rate for spectrally shaped channels.
In the second case, we propose an algorithm for the data rate maximization based on the rate distortion theory when the
statistics of multiple Rayleigh fading subchannels are dissimilar. In particular, we propose an approach that the
channels be divided into several groups. Each group adopts its own M-ary PSK modulation. By using the eligible diversity grouping matrix (EDGM), the subchannels are arranged and grouped more efficiently. The algorithm consists of three loops of computation, such that the inner loop performs rate distortion optimization of energy allocation on each group, the middle loop searches groups in EDGM, and the outer loop carries out searching on the different symbol rates. The results show that, compared to using a water-filling or single-grouping, a higher data rate is obtained by using the proposed DGDRM algorithm over the multiple Rayleigh fading channels.
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