Gigabit Rate Coaxial Cable Access Down Link Key Technology

The convergence of broadband communications network, digital TV network and theInternet has been implemented at present. One of the most important thing is how toreconstruct cable TV network, set up a new high-speed access network, the nextgeneration of broadcast network.However, the peek access rate is only2Mbps in domestic market now. It’s too low tomeet the need of the network convergence. Ethernet IP data transmission over coaxialcable is the hot research topic. The domestic existing High Performance Network overCoax only has physical layer rate of128Mbps, frequency utilization efficiency of7bps/Hz.Thus, we investigate Gbps network over coxial cable, involving the physical layerdownlink, achieving physical layer rate above1Gbps, frequency utilization efficiencyabove8bps/Hz, bit error rate below107.First, parameter of physical layer downlink is proposed. OFDM and high-order QAMis adopted. Transmission rate has achieved up to1,126Mbps in128MHz bandwidth,frequency utilization efficiency of8.8bps/Hz.Second, synchronization scheme of Gbps OFDM system based on coaxial cable isproposed. The frame synchronization method can reach99of acquisition probabilityand104of false-alarm probability; joint synchronization of sampling and CarrierFrequency Offsets is proposed. Scheme of jointly estimating the CFO and SFO uses acontinual pilot defined in our system, the analytical and simulation results show thatMSE of estimation achieving103demands SNR of30dB.Thirdly, channel estimation scheme of Gbps OFDM system based on coaxial cable isproposed. Concerning the phase rotation caused by sampling and carrier frequency error,this scheme uses the preamble sequence of data frame to estimate the channel stateinformation roughly, correcting the channel estimation results. Simulations show thatthis scheme can effectively overcome the impact of the two errors on data equalization,and MSE of estimation achieving103demands SNR of20dB.Finally, to verify the performance of the synchronization and channel estimationschemes, MATLAB simulation platform has been built, float-point and fixed-pointsimulation results are showed. Ber achieving107demandsEs N0of40.5dB.The research in this thesis explores the physical layer of Gbps network over coxialcable, which extends practical values to apply in prototype.