Link Quality Analysis And Repeating Opportunity Assessment In Wireless Family Scenarios

Rate anomaly is a common phenomenon at wireless WI-FI network basing on 802.11 protocols. It is due to the channel competition, which is caused by the STA nodes associated with the same AP (Access Point) and working on the same channel. If one STA node's signal quality becomes worse, which results in lower transmission rate, then it will consume more airtime, so that other STA nodes will occupy less airtime relatively. So the whole network throughput will decreases because of rate anomaly.Coping solutions proposed by researchers inside and outside china can be divided into two categories. One is to change the transmission strategy to time equality, so the STA node with a bad signal quality will bears all the throughput loss other than affecting other STA nodes. The other one is to make use of the broadcast feature of wireless communication, proposing a rational route selection algorithm to substitute the former bad signal quality link. Most of the researchers choose the second one.This design proposal uses repeat function of MAC layer to cope with the rate anomaly, which means using two-hop repeat link to substitute former link. Based on normal family environment with less than 10 nodes, this proposal has three advantages. First, it can keep the throughput balance of all nodes; second, it can also extend the service coverage of AP; third, its realization will be much simpler only considering about one-hop or two-hop link.Link quality estimation is the premise of route selection. Through a research of current mainstream link quality estimation methods, we found that some of these methods have ignore many factors which effect link throughput at actual environment, so that must result in dissatisfied accuracy. In view of these facts, this paper proposes a more practical link quality estimation method. This method doesn't only consider the throughput effects of the physical features, but also optimizes collection method of key quality information such as rate, packet loss rate.On the base of the optimized link quality estimation algorithm, this design proposal uses a concise, low-overhead repeat judgment method. This method have adequately considered channel competition and multi-hop link effect caused by code overhead of transmission node. At last, we propose a compensation algorithm against possible system error to promote the reliability of the whole repeat mechanism.