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We study the performance of cognitive (secondary) users in a cognitive radio network which uses a channel whenever the primary users are not using the channel. The usage of the channel by the primary users is modelled by an ON-OFF renewal process. The cognitive users may be transmitting data using TCP connections and voice traffic. The voice traffic is given priority over the data traffic. We theoretically...
We consider the problem of wireless channel allocation to multiple users. A slot is given to a user with a highest metric (e.g., channel gain) in that slot. The scheduler may not know the channel states of all the users at the beginning of each slot. In this scenario opportunistic splitting is an attractive solution. However this algorithm requires that the metrics of different users form independent,...
We consider the problem of scheduling a wireless channel among multiple users. A slot is given to a user with a highest metric (e.g., channel gain) in that slot. The scheduler may not know the channel states of all the users at the beginning of each slot. In this scenario opportunistic splitting is an attractive solution. However this algorithm requires that the metrics of different users form independent,...
This paper presents an overview of random early detection algorithm and differentiated services on ns2. In the present scenario of computer networks the traffic is increasing exponentially due to which packet losses are also increasing at a great rate. An active queue management in routers and gateways can potentially reduce packet loss rates in the Internet. In this paper we have proposed use of...
We propose a novel, energy-aware, routing protocol for quality-of-service (QoS) support in an infrastructure-less ad-hoc network. Our stability-based, QoS-capable ad-hoc on-demand distance vector (SQ-AODV) protocol is an enhancement of the well-known ad-hoc on-demand distance vector (AODV) protocol. Our protocol utilizes a cross-layer approach, in which information about residual node energy is used...
We propose a robust solution to the problem of multiuser downlink beamforming with constraints on per antenna power and quality of services (QoS). We assume only the erroneous channel state information (CSI) is available at the transmitter, which may arise due to quantization, feedback delay, feedback error, etc., and solve this problem within the framework of worst-case performance optimization....
We consider the problem of centralized routing and scheduling for IEEE 802.16 mesh networks so as to provide Quality of Service (QoS) to individual real and interactive data applications. We first obtain an optimal and fair routing and scheduling policy for aggregate demands for different source- destination pairs. We then present scheduling algorithms which provide per flow QoS guarantees while utilizing...
We study the problem of multiuser downlink beamforming under the assumption that only an erroneous channel state information (CSI) is available at the transmitter. The optimization criterion is to minimize the total transmit power subject to the constraints that the user worst-case signal-to-interference-plus-noise ratios (SINRs) are above a pre-defined quality of service (QoS) threshold. In contrast...
In this paper we develop and numerically explore the modeling heuristic of using saturation attempt probabilities as state dependent attempt probabilities in an IEEE 802.11e infrastructure network carrying packet telephone calls and TCP controlled file downloads, using enhanced distributed channel access (EDCA). We build upon the fixed point analysis and performance insights. When there are a certain...
We develop new scheduling algorithms for the IEEE 802.16d OFDMA/TDD based broadband wireless access system, in which radio resources of both time and frequency slots are dynamically shared by all users. Our objective is to provide a fair and efficient allocation to all the users to satisfy their quality of service
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