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The bandwidth in wireless networks is usually shared by a number of wireless nodes. The channel capacity depends on the number of accessing nodes, time, environmental conditions and location of nodes. Due to varying channel conditions, several issues are observed in the transmission of real time multimedia. The existing research on multimedia streaming can be classified into adaptation techniques...
In a cognitive radio network that employs opportunistic spectrum access, the users are allowed to access a frequency band only when it is not being used by licensed users. Hence, spectrum sensing is of utmost importance, in order to efficiently exploit the unused spectrum and effectively protect the quality of service of licensed networks. For this reason, a time slot has been allocated for spectrum...
This paper proposes a game-theoretic approach to the problem of resource allocation for a CDMA wireless communication network, focusing on code synchronization. To capture the tradeoff between obtaining good synchronization performance and saving as much energy as possible, we propose a noncooperative game in which each pair transmitter-receiver in the network seeks to maximize the ratio of the probability...
One of the challenging problems of cognitive radio networks is the interference which occurs when a cognitive radio accesses a licensed band but fails to notice the presence of the licensed user. To allow the cognitive radio to access the same spectrum band where the primary user is operating creates a problem, the cognitive radio may interfere with the primary system, and hence degrading the quality...
In this work, we look at single user and multiuser Multiple-Input Multiple-Output (MIMO) beamforming networks with Channel Distribution Information (CDI). CDI does not need to be updated every time the channel changes, but only when the statistics of the channel change. Thus, feedback in the network is significantly reduced when compared to CSI schemes. With statistical information, we can only guarantee...
Based on recent results for the vector broadcast channel (BC), the feasibility of the quality of service (QoS) optimization in the multiple-input multiple-output (MIMO) BC with linear precoders and linear equalizers is investigated. Based on the observation that only single data stream transmission must be considered for feasibility, we find that the test for feasibility is the comparison of the sum...
We address in this paper the quality of service (QoS) constrained radio resource allocation problem at the downlink of multiuser multicarrier systems. Based on the trade-off between energy consumption and transmit power within a cross physical and link layer system model, which jointly considers power allocation, adaptive modulation and coding and ARQ/HARQ retransmission protocols, a transmit power...
This paper considers the issue of spreading code allocation and receiver optimization in a CDMA-based multiuser data network. Assuming that non-linear serial interference cancellation is performed at the receiver, the problem of noncooperative SINR maximization with respect to each user's spreading code and uplink receiver is first considered. It is shown that iterative SINR maximization converges...
To support the quality of service in wireless multimedia communications, wireless systems should work well in typical wireless environments characterized by the path loss of the signals, multipath fading, interference to adjacent channels, and random errors. A variety of researches in the application-layer have been proposed to adapt the video encoder to the link quality by compressing the data with...
In this paper, the problem of cooperative beamforming is investigated in a heterogeneous underlay cognitive network. A major difference exists between a conventional cooperative beamforming problem and cooperative beamforming in a CR (Cognitive Radio)network due to the interference constraints imposed by primary network. These constraints can greatly increase the complexity of the related optimization...
In this paper we investigate admission control and power allocation for cognitive radios in an underlay network. We consider the problem of maximizing the number of supported secondary links under their minimum QoS requirements without violating the maximum tolerable interference on primary receivers in a cellular network. An optimal solution to our problem is shown in previous works to be NP-hard...
We study the problem of power control in the physical layer of wireless ad hoc networks with a view to increasing the network's quality of service, reducing power consumption, and decreasing interference. We propose a new power control algorithm, and use game theory to analyze its performance, where each user's quality of service is a function of its signal-to-interference-plus-noise-ratio (SINR)...
In this paper, the problem of maximizing the number of users that can be served in a wireless network under QoS requirements and transmitter power limitations is studied. This problem is mathematically defined and then transformed into a novel form which is solvable by geometric programming. A suboptimum solution is proposed and the performance of this method is investigated by simulations.
In this paper we provide an adaptive cross layer design in single input multiple output systems which combines adaptive modulation at the physical layer with truncated automatic repeat request at the data link layer to maximize the spectral efficiency. The maximization is performed in the presence of imperfect channel state information at the receiver under prescribed quality of service such as delay...
Effective capacity is a useful technique to characterize the system throughput with statistical delay-constrained quality of service (QoS) guarantees. In this paper, we integrate effective capacity theory into superposition-coding (SPC) based multicast transmission to devise the efficient channel-aware multicasting scheme in wireless networks. Specifically, we propose to optimize the effective capacity...
We consider a generalised multi-receiver radio network under a quality-of-service (QoS) constraint that involves generalised carrier-to-interference ratios. This model includes as special cases many well-known schemes, such as those discussed by Yates (JSAC, 13(7): 1341-1348, 1995). A simple feasibility condition for the QoS targets, and a power-vector that yields those targets are given in closed...
This paper studies the benefits that cooperation brings to a cognitive radio network. The proposal in this paper considers that secondary unlicensed users are allowed to opportunistically use the radio spectrum allocated to the primary licensed users, as long as they agree on facilitating the primary user communications by cooperating with them. We refer to this approach as overlay paradigm for cognitive...
Despite all the work being done so far in scheduling for wireless networks, the transmission scheduling problem with specific constraints is not yet fully understood and explored. In this work, we find the minimum number of time-slots (or channels) required in any given network and the corresponding transmitting powers, such that all communication requests are being processed correctly, while fulfilling...
Ultra Wideband technology (UWB) is an emerging technology that has proven to be quite suitable for short range applications. This paper is part of an ongoing research for using UWB technology for positioning team-sport players on a playground, Simulation is conducted for a number of “players” who are carrying RFIDs transmitting signals with biometric information data about each player to a number...
Mobile ad Hoc network (MANET) and sensor networks have no fixed infrastructures such as Base Stations and Towers, and have limited bandwidth across the network elements. They use multi-hop radio communications to deliver multi-service (voice, data, and video) information. Each network element can either send a packet or receive a packet but not both. Therefore, synchronization between radios must...
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