Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, 2004. / Thesis Advisor(s): John C. McEachen. Includes bibliographical references (p. 51-52). Also available online.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): John C. McEachen. Includes bibliographical references (p. 55-56). Also available online.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

No description available.

Most contemporary modems provide a bit-oriented service at the physical layer of the OSI reference model. They do not provide any specific support for packet data transmission. A novel Hop-Aligned Slow Frequency Hopping (HA-SFH) concept is proposed to provide a packet traffic service in a Partial Band Jamming (PBJ) environment. Frequently, SFH is used together with deep interleaving and powerful Forward Error Correction (FEC) to combat PBJ. The proposed HA-SFH exploits the error control mechanism of the link layer packet protocol and reduces the data redundancy by using a low gain FEC, it results in a more bandwidth efficient system. The HA-SFH and deep interleaving SFH (DI-SFH) performance were analysed and compared by using a series of simulations and experiments employing a network simulator and hardware such as Viterbi decoders and a channel noise simulator, etc. The results are presented in terms of throughput and average frame delay, which are more meaningful qualities than BER for packet traffic. It shows concrete results that HA-SFH performs 2 times better than DI-SFH in terms of throughput under PBJ. This thesis also discusses a wide range of technical issues involving the implementation of HA-SFH such as the coding level required, protocol enhancement, networking traffic, adaptive FEC, channel state estimation, etc. It also explores an adaptive code rate system called the Smart Codec (SmCodec), which can be integrated into HA-SFH. The further development of the SmCodec also makes it a suitable system for use in commercial PSK modems to combat the effect of channel fading (eg. from rain). A new channel state estimation technique is also proposed. It estimates the channel state from the block error rate and the required estimation time is as low as 2 seconds for the most required range of E_b/N_o at a 64 kbps link (the estimation time decreases when the link speed increases).

In the world of networked system, average consensus is an important dimension of co-ordinate control and cooperation. Since the communication medium is digital, real value cannot be transmitted and we need to perform quantization before data transmission. But for the quantization, error is introduced in exact value and initial average is lost. Based on this limitation, my 16 bit quantization method (sending MSB in 1-4 cycle and MSB+LSB in 5th cycle) reduces error significantly and preserves initial average. Besides, it works on all types of graphs (star, complete, ring, random geometric graph). My other algorithm, distributing averaging algorithm (PQDA) with probabilistic quantization also works on random geometric graph, star, ring and slow co-herency graph. It shows significant reduced error and attain strict consensus.

M.Ing. (Electrical and Electronic Engineering Science) / This study presents a simple methodology developed to set up and establish a simplex communication system over a power line using load signatures. Traditional concepts such as normalization and matched filtering form the core of these algorithms. The analysis also relies extensively on the voltage and current measurements made over a fixed period of time on a single phase. Furthermore, analyses on the capacity of this kind of system are also presented, taking into consideration various disturbances.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Javier Garcia-Frias, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 147-156). Also available in print.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, March 2004. / Thesis advisor(s): John C. McEachen. Includes bibliographical references (p. 67-68). Also available online.