Study On All Digital Receiving Technologies And MAC Layer For The HFC Networks

The access networks have become the bottleneck of B-ISDN and Information Superhighway in their development. The Hybrid Fiber/Coax ( HFC ) network is one of the broadband access networks with high competitive power, and is expected to be the solution of the "last mile" for the Information Superhighway.The thesis presents the study of the MAC protocols and burst mode transmission techniques, which are the two key aspects in HFC networks. All digital implementation of burst mode modulators and demodulators is preferred for its advantages.Chapter 1: Survey the fundamental and development of HFC networks, burst mode transmission techniques and all digital modulation and demodulation techniques.Chapter 2: The fundamental theory and implementation methodology of all digital receiver are studied. Firstly , this paper analyses a series of problems caused within the sampling and quantifying process, including analog prefiltering. sampling rate and IF configuration, etc. The ML-Function and optimal digital receiver algorithm and structure are then studied thoroughly, which are nonrealizable since it contains noncausal operations. After that . two approaches from which realizable algorithm and structure can be derived are discussed. The special and also key aspects , interpolation filters design and control . of all digital receivers are studied thoroughly. The paper states that polynomial based interpolators are not optimal, but they can be efficiently implemented using Farrow structure. At last . a new synthesis technique for polynomial based interpolators is proposed.Chapter 3: Firstly, two levels of synchronization, network synchronization and burst synchronization, usually to be performed in the multiple access system are discussed. After that, burst synchronization is studied thoroughly. The author proposes a dedicated algorithm for clock and carrier synchronization in a QPSK demodulator, which is based on the use of a very short special carrier preamble modulated by a known pattern. An all digital preambleless burst mode PSK demodulator is also proposed and studied. The upstream channel characteristics of HFC network and anti-noise and interference techniques are then analysed. At last, this paper introduces the function implementation of all digital burst mode modulator and demodulator for upstream channel, which is compatible with MCNS Specification. The hardware frame figures and photos are also given.Chapter 4: Firstly, the performance of TDMA/FDMA and CDMA in the upstream channel is discussed. The MAC protocol for HFC network based on TDMA/FDMA is studied thoroughly. After that , the performance of IEEE802.14 Protocol and MCNS Protocol is analysed and compared. The station acquisition process is also studied. At last , the key techniques on physical dependent layer of DS-CDMA upstream scheme are studied.