Research On Adaptive Bit Allocation Method In Cable Communication System

As an indispensable part of communication field,cable communication is mainly responsible for data transmission in telephone communication,submarine communication,logging communication and so on.As the amount of transmitted data continues to expand,the transmission rate becomes the main problem to limit cable transmission.The application of OFDM technology in cable transmission system has improved the transmission rate.However,in this system,each sub-channel is modulated and demodulated by a unified modulation method,and the transmission rate is suppressed by the deep fading sub-channel.It is the key to further improve the transmission rate to use adaptive technology to track the channel changes at any time and adopt different modulation methods according to the sub-channel characteristics.Based on the study of transmission characteristics of cable communication system,a new adaptive bit-allocation algorithm-proportional greedy algorithm is proposed.The algorithm takes into account the variation of the signal-to-noise ratio gap under different modulation modes of MQAM.Firstly,the power allocation weight value is obtained by the SNR and the SNR gap,then the power of each sub-channel is obtained by the allocation weight value,and the integer bits and the corresponding power are obtained,then the remaining power is allocated by greedy algorithm,and finally the best bit allocation scheme is obtained.After MATLAB modeling and simulation,and compared with several commonly algorithms in bit allocation? bit error rate and algorithm complexity,the advantages of the algorithm are highlighted,such as low computational complexity and accurate bit allocation.The feasibility of the algorithm in the real-cable communication system is fully proved by the measurement on the cable simulator.