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In this paper, we consider a wideband spectrum sharing system where a secondary user can share orthogonal frequency bands with a number of primary users, each licensed to use an individual band. We address the problem of ergodic capacity maximization of the secondary user subject to an average sum (across the bands) transmit power constraint on the secondary user and individual average interference...
In this paper, we study the distributed multichannel spectrum sharing problem for the cognitive radio networks (CRNs). We are interested in dynamic spectrum sharing schemes that maximize the spectrum utilization of the cognitive network while appropriately protecting primary users. Existence and optimality of the Nash Equilibrium (N.E.) are investigated. Distributed Multichannel Spectrum Sharing (MCSS)...
Traditionally, the channelization structure in IEEE 802.11-based wireless LANs has been fixed: Each access point (AP) is assigned one channel and all channels are equally wide. In contrast, it has recently been shown that even on commodity hardware, the channel-width can be adapted dynamically purely in software. Leveraging this capability, we study the use of dynamic-width channels, where every AP...
The paper describes a system architecture and formulation of the Dynamic Subchannel Allocation problem in IEEE 802.16e networks. According to it, the DSA algorithm operates as an extension of a IEEE 802.16 time scheduler, trying to exploit the benefits of the OFDMA mode. Simulation results show a considerable improvement, compated to the legacy system, especially in terms of channel errors.
We present a distributed algorithm for allocating power among multiple interfering transmitters in a wireless network using orthogonal frequency division multiplexing (OFDM). The algorithm attempts to maximize the sum over user utilities, where each user's utility is a function of his total transmission rate. Users exchange interference prices reflecting the marginal cost of interference on each sub-channel,...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
In this paper, we address the issue of transmission power control (TPC) in wireless ad hoc networks. Power control plays an important role in energy saving and network performance enhancement. However, the existing TPC schemes either face the problem of hidden and exposed terminal or have additional hardware requirements. We propose a novel distributed power control protocol, called Receiver Initiated...
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