The Physical Layer Key Techniques In The Digital Signal Processing Of Gigabit Rate EOC

The3networks of TV broadcasting, telecom and Internet are the important directionof Information infrastructure in our country. The TV broadcasting is superior inresources and numbers in three net fusions. To speed up the digital cable television,two-way transformation of HFC is a urgent problem in NGB.However, the EoC developed has maximally100M physical layer rate, which isdifficult to meet the demand of high-spead data rate. Therefore, this paper researches thePhysical Layer of the gigabit access system over coaxial cable.This paper mainly studies the techniques of synchronization and channel estimationin the gigabit access system over coaxial cable. Meanwhile, the solution and keytechniques for implementation is discussed.First, analysis the physical layer signal processing. The feasibility of Gibit access ratebased on the multipath, time-invariant, low noise coaxial cable network channel isanalyzed. Then proposes a design scheme of OFDMA transmission with4096QAMdownlink and256QAM uplink. So the128M bandwidth maximum load1126M bit ratevar4channels at10^-7bit error rate. The spectrum effectiveness is8.01bps/Hz.Second, present the scheme of the physical synchronization and channel estimation.This paper analyses the symbol timing error, carrier frequency offset, sampling timedeviation in the multipath Gaussian channel of OFDM system. Based on the measuredcoaxial cable channel, the uplink synchronization and channel estimation scheme isdesigned. The downlink receiver supports4096QAM demodulator threshold of39.5dBat10-7bit error rate, and The uplink receiver supports256QAM demodulator thresholdof27.5dB at10-7bit error rate through fixed-point simulation.Third, design the physical layer DSP software. The synchronization and channelestimation scheme is realized on TMS320TCI6488of Ti DSP. First, design the systemgeneral architecture and detail modules. Second, workout the scheme by DSP softwareaccording to modularization. Fanlliay, give an example of the terminal DSP subsystem.Finally, make engineering vertification of digital signal processing in the physical.Built the testing system in the laboratory environment. The coaxial experimentalnetwork consists of one local controller and1terminals by4aggrate channels, The testresult compared with fixed-point simulation with MATLAB is less than2dB.In this paper, the synchronization and channel estimation for OFDMA has beendiscussed. The digital signal processing software has been used in the prototype of EoC.It has practical and economic value.