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Coordinated information processing by the base stations of multi-cell wireless networks enhances the overall quality of communication in the network. Such coordinations for optimizing any desired network-wide quality of service (QoS) necessitate the base stations to acquire and share some channel state information (CSI). With perfect knowledge of channel states, the base stations can adjust their...
Interference mitigation and adaptive multi-user resource allocation are among the most promising technological breakthroughs that should improve capacity of future broadband wireless communications. In a multi-cell scenario, where co-channel interference is the performance limiting factor, discrete-rate resource allocation algorithms, selecting those channels with best Signal-to-Interference and Noise-Ratio...
This study addresses the general problem of efficient resource management in wireless networks with arbitrary time-varying topologies. Communication channels are assumed to generally accommodate multiple simultaneous transmissions. In this context, we focus our attention on the problem of distributed transmission power allocation and medium access by links (transmitter-receiver pairs) that require...
This paper proposes an adaptive bandwidth control scheme for autonomous distributed networks. Based on the consideration that the carrier sense multiple access with collision avoidance (CSMA/CA) is not efficient in terms of throughput due to its strict collision avoidance process, this paper employs a dynamic spectrum control (DSC) in which a certain number of discrete spectra having the highest signal...
Troubleshooting of wireless networks is a challenging network management task. We have developed, in a previous work, a new troubleshooting methodology, which we named Statistical Learning Automated Healing (SLAH). This methodology uses statistical learning, in particular logistic regression, to extract the functional relationships between the noisy Key Performance Indicators (KPIs) and Radio Resource...
A four terminal Gaussian network composed of a source, a destination, an eavesdropper and a jammer relay is investigated when the jammer relay is causally given the source message. The source aims to increase the achievable secrecy rates, whereas the jammer relay aims to decrease it. To help the eavesdropper and to decrease achievable perfect secrecy rates, the jammer relay can use pure relaying and/or...
In this paper, we propose an interference aware throughput maximizing scheduler for cognitive radio networks (CRNs) as part of a MAC layer resource allocation framework. In the considered CRN scenario, the cognitive users with multiple antennas are coordinated by a centralized cognitive base station. We evaluate the performance of our proposed scheme using analysis of variation (ANOVA) technique....
This paper addresses multiple access in MIMO wireless networks. It compares two distributed interference alignment techniques, in space and in frequency, that both aim at removing interferences through orthogonalization. The theoretical advantages and drawbacks of each technique are highlighted. Then, the multiplexing gain and the computational complexity are analytically evaluated. It is shown that...
We propose a scheme for maintaining the requested SIR of each user under uncertainty of system parameters in the power control of interference limited wireless networks. In doing so, we keep the outage probability of users below their predefined threshold with minimal power consumption. To reduce the complexity, we apply the notion of chance constraint robust optimization to the outage probability...
Is the temporal dimension alone sufficient to characterize contacts in opportunistic networks? Several studies analyze the temporal aspect of contacts with significant results concerning contact and inter-contact distributions. Nevertheless, only the temporal dimension does not give a complete overview of contact characterization. In this paper, we propose the surround indicator as a metric to exhibit...
In the planning of cellular networks, link budget calculation is the first step to get the maximum allowable cell radius that guarantees a target signal to interference plus noise ratio (SINR) with a certain level of outage probability at the cell border. The interference margin as one of key inputs for link budget is used to compensate for co-channel interference. In this paper, a mathematical analysis...
When both a high-priority and a low-priority system share a common frequency band, the low-priority station must sense the presence of the high-priority system, and if required, postpone its transmission or reduce its transmit power to avoid possible interference. To compensate, transmission opportunities of the low-priority system should be ensured as much as possible. Using a transmission scheme...
To maximize the gain of multi-hop transmissions, we have to let the number of hops as small as possible, decreasing multi-hop transmission delay. In this paper, we propose how the average number of hop counts can be reduced in wireless multi-hop networks by constructing a few long-range edges that can act as if they were highways in the networks. For this purpose, we adopt the concept of small-world...
This paper establishes a framework for designing fast, robust, and distributed algorithms for solving network utility maximization problems with coupled objective functions. We use two case studies in wireless communications to illustrate the key ideas: reverse-engineering the algorithm based on the KKT conditions of the optimization problem, and proving the properties of the algorithms using monotone...
A cognitive radio wireless network is investigated, in which a number of primary users (PUs) transmit in orthogonal frequency bands. There are also a number of secondary users (SUs) in the network, which monitor transmission opportunities in these frequency bands by collaboratively detecting whether each PU is transmitting. Each SU can participate in detecting only one PU's transmission at a time...
Cognitive radio methodologies have the potential to dramatically increase the throughput of wireless systems. Herein, control strategies which enable the superposition in time and frequency of primary and secondary user transmissions are explored in contrast to more traditional sensing approaches which only allow the secondary user to transmit when the primary user is idle. In this work, the optimal...
Hundreds of papers over the last two decades have studied the theory of distributed scheduling in wireless networks, including a number of them on stability or utility maximizing random access. Several publications in 2008 studied an adaptive CSMA that in theory can approach utility optimality without any message passing under a number of assumptions. This paper reports the results from the first...
This paper investigates the properties of social choice functions, that represent resource allocation strategies in interference coupled wireless systems. The resources can be physical layer parameters such as power vectors or antenna weights. The paper investigates the permissible social choice functions, which can be implemented by a mechanism in either Nash equilibria or dominant strategy - for...
CSMA policies are examples of simple distributed scheduling algorithms in wireless networks. In this paper, we study the delay properties of CSMA in the limit of large networks. We first define an ideal network under which CSMA becomes memoryless in that the delay to access the channel becomes an exponential r.v. independent of the past. We then show that, in the limit of large bipartite graphs with...
As communication is making the whole world a global village, there seems to be tremendous pressure on the service providers in this field. The greatest demand is for Quality Of Service (QoS) wherein the most important role is played by Interference. There are numerous parameters leading to interference in both wired and wireless communication. In this paper an attempt is made to minimize interference...
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