Modelling Throughput and Starvation in 802.11 Wireless Networks with Multiple Flows

Abstract

Abstract-Carrier sense multiple access (CSMA) protocols require stations that wish to transmit to first check the shared medium for ongoing transmissions. However, in wireless networks stations may not be able to sense transmissions from all other stations; hence those at different locations can experience different amounts of contention, resulting in unfairness and possible "starvation" (inability to acquire channel access for long periods). In this paper we model how the 802.11 MAC protocol allocates bandwidth among multiple saturated flows in a linear topology when not all senders are within sensing range. We consider a specific class of topologies consisting of n independent flows, where each sender can sense k neighbors on either side. Our work uncovers global interactions among flows leading to startling sensitivities in node throughput. A new model to predict the long-term throughput of each flow under saturation is presented and our model results validated via OPNET simulations.

Throughput Modeling of Large-Scale 802.11 Networks

“…As stated in [6] a large-scale network is very hard to model. A first attempt has been made in [7] to model the throughput of large-scale networks.…”

“…The authors also provide an interesting discussion concerning the impact of the IEEE 802.11 MAC protocol. The idea of using a sequence of states of active or transmitting nodes, where each possible state is an independent set in the conflict graph as presented in [4,5] has been extended in [6] to provide a simple model for equally-distant string topologies of 802.11 terminals. However, their model is less accurate when the length of the string increases.…”

Detection and Prevention of Wormhole Attacks in Wireless Sensor Networks

“…Every mobile node utilizes a similar scheduling algorithm for routing the data packets. In this model, it consider the conventional scheduling (priority scheduling) usually used in mobile ad hoc networks [6]. In buffer management, drop tail policy is utilized with no-priority scheduling and it works when buffer is empty otherwise drops the incoming packets.…”

“…So the stream gets starved and the data transfer capacity is not productively used by the system. So to stay away from this issue we present a Starvation Mitigation Algorithm (SMA) by which we can give productive data transfer capacity use by every one of the nodes in a network and give decency in a" network [6].…”

“…The specified value chosen must be unique among the network interfaces on that each node with no importance need not be coordinated with any other nodes in choosing their own interface indices. On many operating systems, each network interface is identified by a unique value and can be used for this purpose; for example, the if index field in the if net structure for a network" interface in BSD Unix-based networking stacks [6] can be used directly by a node for the interface index for that network interface.…”