一种高效的计算带宽请求微时隙的算法

A High Performance Algorithm for Computing Bandwidth Requested Mini-Slots

首先提出了一种基于HFC网络和DOCSIS规范精确计算带宽请求微时隙的算法,该算法根据用户数据长度、MAC管理报文的大小计算出不同RF(射频)条件下发送上行数据所需要的最少微时隙数,有效提高了网络带宽利用率.其次,在算法实现上提出了一种优化的快速实现方法,引入Hash算法,构造了一个Hash函数,大大降低了算法的运算时间,可满足实时系统的要求.该算法已成功应用于由自主开发的物理层和MAC层芯片组成的HDTV(高清晰度电视)双向系统平台.实际网络环境下的测试结果表明该算法及其实现完全满足HDTV双向点播、VoIP、Internet网络通信等应用需求,在实际应用中表现出了良好的性能和可靠性.

Firstly, this paper proposes an algorithm which can calculate accurately the total amount of mini-slots requested in the bandwidth request frame, based on HFC networks and DOCSIS specifications. According to the size of user data packet or MAC management message, the algorithm calculates the least amount of mini-slots needed by CM to transmit upstream frame in the case of different RF （Radio Frequency） parameters, thereby efficiently increasing the net work bandwidth utilization ratio. Secondly, this paper also describes an optimized and high speed implementation for the algorithm. A Hash function is introduced, which results in the great reduction of the program runtime, and thus, the implementation method meets the demands of realtime systems. The algorithm has been successfully applied to the bidirectional system platform for HDTV（High Definition Television）, which consists of PHY chip and MAC chip developed in authors lab. The algorithm meets the demands of applications, including bidirectional VOD of HDTV, VolP, and Internet data service etc. The tests in real network conditions show that the system provides a good performance and reliability.