The pipeline transmission of frame blocks in noisy computer channels

Abstract

The process of pipeline transmission of information frames at the second level in noisy channels of computer networks has been studied. As a model, we use a Gaussian memoryless channel, in which bit errors are independent and uniformly distributed over the bits of the transmitted information. The error intensity is reflected by the BER (Bit Error Rate) parame-ter. Information is transmitted using frame blocks, the size of the blocks coincides with the size of the sliding window. The dependence of the total number of frames transmitted success-fully and damaged during transmission on the volume of the transmitted application, the length of the window and the probability of its successful transmission has been determined. Analysis of the obtained data shows that with increasing window length and interference in-tensity (BER), the number of frames distorted at the first stage of transmission increases. The distorted frames must be transmitted at the second stage when filling the sliding window with the next block of frames. This next block contains both the frames distorted at the first stage and the frames following in sequence, which are transmitted for the first time. It is shown that with a relatively small error rate BER=5‧10-7 and the use of the window contained n=40 standard frames, the number of copies of damaged frames transmitted as part of the window at the second stage does not exceed 20%. At BER=10-6 this number is already 40%, i.e. some of these frames will be re-distorted during transmission at the second stage and will be in-cluded in the third window. This will lead to an increase in the time required to form the same sequence of frames that arrived from the third network layer. At higher interference levels (BER= 5‧10-6), the situation worsens significantly. If, with a small window of n=8, the number of frames distorted at the first stage of transmission approaches 40, then at n=40 it is already 92%. In this case, there is a significant probability of using the third and fourth stages of transmission to form the required sequence of frames. To avoid a significant reduction in network throughput, it is necessary to limit the window length to n=6 at BER= 5‧10-6 and n=20 at BER=10-6.