A multicast overlay scheme for wavelength division multiplexed passive optical networks.

Zhang, Yin.Thesis submitted in: December 2008.Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.Includes bibliographical references (leaves 56-60).Abstracts in English and Chinese.Chapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Telecommunications network hierarchy --- p.2Chapter 1.2 --- PON architectures for access networks --- p.4Chapter 1.2.1 --- TDM-PON --- p.5Chapter 1.2.2 --- WDM-PON --- p.7Chapter 1.3 --- Data delivery mode in WDM-PON --- p.8Chapter 1.3.1 --- Point-to-point --- p.8Chapter 1.3.2 --- Broadcast --- p.9Chapter 1.3.3 --- Multicast --- p.10Chapter 1.4 --- Motivation of this thesis --- p.10Chapter 1.5 --- Outline of this thesis --- p.13Chapter Chapter 2 --- Previous Multicast Architectures in WDM-PON --- p.14Chapter 2.1 --- Introduction --- p.15Chapter 2.2 --- Previous WDM-PON architectures with multicast capability --- p.15Chapter 2.2.1 --- Subcarrier multiplexing --- p.16Chapter 2.2.2 --- All-optical based multicast enabled architecture --- p.18Chapter 2.3 --- Summary --- p.21Chapter Chapter 3 --- A Multicast enabled WDM-PON Architecture Using ASK-DPSK Orthogonal Modulation --- p.23Chapter 3.1 --- Introduction --- p.24Chapter 3.2 --- System architecture --- p.25Chapter 3.3 --- Experimental Demonstration --- p.27Chapter 3.4 --- Discussion --- p.31Chapter 3.5 --- Summary --- p.36Chapter Chapter 4 --- A WG filtering and its suppression in quaternary ASK-DPSK based multicast enabled WDM-PON --- p.37Chapter 4.1 --- Introduction --- p.38Chapter 4.2 --- Principle of narrowband filtering --- p.38Chapter 4.3 --- Simulation model --- p.40Chapter 4.4 --- Simulation results and discussion --- p.42Chapter 4.4.1 --- Different extinction ratios --- p.43Chapter 4.4.2 --- Different AWG filter shape and bandwidth --- p.47Chapter 4.5 --- Summary --- p.50Chapter Chapter 5 --- Summary and Future Works --- p.51Chapter 5.1 --- Summary of the thesis --- p.52Chapter 5.2 --- Future works --- p.53List of Publications --- p.55BIBLIOGRAPHY --- p.5

Performance evaluation for communication systems with receive diversity and interference

Optimum combining (OC) is a well-known coherent detection technique used to combat fading and suppress cochannel interference. In this dissertation, expressions are developed to evaluate the error probability of OC for systems with multiple interferers and multiple receiving branches. Three approaches are taken to derive the expressions. The first one starts from the decision metrics of OC. It facilitates obtaining closed-form expressions for binary phase-shift keying modulation. The second approach utilizes the moment generating function of the output signal to interference plus noise ratio (SINR) and results in expressions for symbol and bit error probability for multiple phaseshift keying modulation. The third method uses the probability density function of the output SINR and arrives at expressions of symbol error probability for systems where the interferers may have unequal power levels. Throughout the derivation, it is assumed that the channels are independent Rayleigh fading channels. With these expressions, evaluating the error probability of OC is fast, easy and accurate. Two noncoherent detection schemes based on the multiple symbol differential detection (MSDD) technique are also developed for systems with multiple interferers and multiple receiving branches. The first MSDD scheme is developed for systems where the channel gain of the desired signal is unknown to the receiver, but the covariance matrix of the interference plus noise is known. The maximum-likelihood decision statistic is derived for the detector. The performance of MSDD is demonstrated by analysis and simulation. A sub-optimum decision feedback algorithm is presented to reduce the computation complexity of the MSDD decision statistic. This suboptimum algorithm achieves performance that is very close to that of the optimum algorithm. It can be shown that with an increasing observation interval, the performance of this kind of MSDD approaches that of OC with differential encoding. The second MSDD scheme is developed for the case in which the only required channel information is the channel gain of the interference. It is shown that when the interference power level is high, this MSDD technique can achieve good performance

Higher order modulation formats for high speed optical communication systems with digital signal processing aided receiver

The drastic increase in the number of internet users and the general convergence of all other communication systems into an optical system have brought a sharp rise in demand for bandwidth and calls for high capacity transmission networks. Large unamplified transmission reach is another contributor in reducing deployment costs of an optical communication system. Spectrally efficient modulation formats are suggested as a solution to overcome the problems associated with limited channels and bandwidth of dense wavelength division multiplexing (DWDM) optical communication systems. Higher order modulation formats which are considered to be spectrally efficient and can increase the transmission capacity by transmitting more information in the amplitude, phase, polarization or a combination of all was studied. Different detection technologies are to be implemented to suit a particular higher order modulation format. In this research multilevel modulation formats, different detection technologies and a digital signal processing aided receiver were studied in a practical optical transmission system. The work in this thesis started with the implementation of the traditional amplitude shift keying (ASK) modulation and a differential phase shift keying (DPSK) modulation systems as they form the basic building block in the design of higher order modulation formats. Results obtained from using virtual photonics instruments (VPI)simulation software, receiver sensitivity for 10Gbpsnon-return-to-zero (NRZ), amplitude phase shift keying (ASK) and DPSK signals were measured to be -22.7 dBm and -22.0 dBm respectively. Performance comparison for the two modulation formats were done over different transmission distances. ASK also known as On-Off keying (OOK) performed better for shorter lengths whereas DPSK performed better for longer lengths of up to90km.Experimental results on a 10 Gbps NRZ- ASK signal gave a receiver sensitivity of -21.1 dBm from digital signal processing (DSP) aided receiver against -19.8 dBm from the commercial bit error ratio tester (BERT) yielding a small difference of 1.3 dB hence validating the reliability and accuracy of the digital signal processing (DSP) assisted receiver. Traditional direct detection scheme and coherent detection scheme performances were evaluated again on a 10 Gbps NRZ ASK signal. Coherent detection that can achieve a large unamplified transmission reach and has a higher passive optical splitting ratio was first evaluated using the VPI simulation software. Simulation results gave a receiver sensitivity of -30.4 dBm forcoherent detection and -18.3 dBm for direct detection, yielding a gain in receiver sensitivity of 12.1 dB. The complex coherently detected signal, from the experimental setup gave a receiver sensitivity of -20.6 dBm with a gain in receiver sensitivity of 3.5 dBm with respect to direct detection. A multilevel pulse amplitude modulation (4-PAM) that doubles the data rate per channel from10 Gbps to 20 Gbps by transmitting more information in the amplitude of the carrier signal was implemented. This was achieved by modulating the optical amplitude with an electrical four level amplitude shift keyed (ASK) signal. A receiver consisting of a single photodiode, three decision circuits and a decoding logic circuit was used to receive and extract the original transmitted data. A DSP aided receiver was used to evaluate the link performance. A receiver sensitivity of -12.8 dBm is attained with a dispersion penalty of about 7.2 dB after transmission through 25 km of G.652 fibre