Srikant Kuppa

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Cognitive radios (CR) have the ability to dynamically adapt to local spectrum availability. In a network comprised of CR-enabled devices, layer-2 auto-configuration involves determining a common set of channels to facilitate communication among participating nodes. This is a unique challenge as nodes in the CR network may be unaware of (a) their neighbors(More)
Frame aggregation is one of the several enhancements proposed by IEEE 802.11 Task Group to improve channel utilization. However, a static assignment of aggregate size may result in the following performance trade-off: a small value might be insufficient to mitigate the transmission overheads, thereby nullifying the whole purpose of frame aggregation;(More)
In this paper, we study the two medium access control (MAC) sublayer policies, namely, schedule after backoff (SAB) and schedule before backoff (SBB), which offer differentiated services in IEEE 802.11-based wireless networks. Both policies control channel access based on frame priorities. In the SAB policy, each node maintains concurrent backoff instances(More)
The IEEE 802.11 distributed coordination function (DCF) does not require the presence of a central controller (access point). It is based on carrier sense multiple access with collision avoidance and binary exponential backoff. Under saturation conditions, DCF operates very far from the theoretical limit. Enhancements to the DCF scheme to achieve the(More)
Cognitive radios CR have the ability to dynamically adapt to local spectrum availability. In a network comprised of CR-enabled devices, layerauto-configuration involves determining a common set of channels also referred to as the global channel set to facilitate communication among participating nodes. This is a unique challenge as nodes in the CR network(More)
The IEEE 802.11 distributed coordination function (DCF) offers only best-effort service. The enhanced DCF (EDCF) scheme supports quality of service by establishing a probabilistic priority mechanism to access the shared wireless medium. EDCF defines four access categories, namely, AC.VO, AC-VI, AC-BE and AC-BK to support voice, video, best-effort and(More)
We present a cluster-based network control mechanism in which the underlying network is divided into disjoint clusters of nodes (fig. 1). When number of clusters is one, the mechanism behaves like fixed-alternate path routing; when equal to number of nodes, it becomes adaptive routing. Clusters consist of special and non-special nodes. Special nodes help in(More)
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