No abstract

Wireless LANs have been widely deployed, and multiple access points (APs) will be much more likely to be available there for STAs, which can roam from one AP to another by some rule. We here focus on an efficient and fair way to use the wireless access resources provided by multiple APs. In particular, our major concern is to develop a decentralized way to enable each of STAs to select an appropriate one of available APs independently. A straightforward way is to select an AP with strongest signal, which will be, however, shown to need further improvement. Hence, we propose decentralized AP selection strategies to achieve an efficient and fair share of wireless access resources, and evaluate them by simulations. Through our results, the proposed strategies can attain an excellent throughput performance by use of the number of active STAs sharing each AP even if STAs employ the strategies only when entering the wireless LAN. In addition, if STAs roam from one AP to another in response to changing situation, the total throughput and fairness can be further improved very much. keyword

No abstract

Reactive congestion control based upon two thresholds is analyzed. Under the congestion control treated here, a multiplexer or transit node in the network recognizes congestion when its queue length reaches some pre-determined threshold value, denoted by H. The congested node then explicitly informs the sources sharing the node of its congestion in some way to mark a forward congestion notification bit in the header of cells if provided, or to directly send control cells to those sources. The sources then stop the cell transmission according to the feedback information received. The relief of congestion is recognized by the node when its queue length decreases to some low-threshold, L, and informs the sources that the sources can again start the cell transmission. In this paper, we investigate this sort of congestion control by forming a queueing network, in which multiple sources and a single node are explicitly modeled. Through an analysis, we discuss the impact of those two thresholds to performance of the congestion control.

No abstract