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Interference in wireless networks results in interdependent communication links between the nodes. Therefore, cross-layer design is essential and makes optimization of wireless networks complicated. In this paper, we study the problem of maximizing the information flow for a multicast session over a wireless network. Different scheduling and coding strategies to handle the interference, including...
The rate optimization for wireless networks with low SNR is investigated. While the capacity in the limit of disappearing SNR is known to be linear for fading and non-fading channels, we study the problem of operating in low SNR wireless network with given node locations that use network coding over flows. The model we develop for low SNR Gaussian broadcast channel and multiple access channel respectively...
In this paper, we study the optimization of an ad-hoc cognitive radio network (CRN) coexisting with a multi-cell primary radio network (PRN) utilizing spectrum underlay. To maximize the weighted sum rate (WSR) of the CRN, in contrast to the exclusive subchannel assignment (ESA) method considered in former results, we design shared subchannel assignment (SSA) method to approach the performance limit...
We consider a relay network with multiple users and propose a signal-to-interference and noise-ratio (SINR) balancing based relay signal forwarding scheme. Each relay receives a combined signal from multiple sources and processes it using a complex valued scalar and transmits towards the destinations so that the SINR at the receiver of each user is maximised. We solve this problem using semidefinite...
It is known that in a cognitive random wireless network, the aggregate interference from secondary network is not Gaussian. Using Shannon's bound for the capacity of general additive channels, Gaussian interference/noise is the worst case due to its maximum entropy property which leads to minimum capacity. Therefore, it is favorable to have the distribution of interference as far from Gaussian as...
We consider the energy-bandwidth tradeoff in a 2-dimensional multi-hop wireless network with spatial reuse. Spatial reuse is introduced to improve the bandwidth efficiency but also causes interference. In this paper, we propose a new transmission energy selection strategy in interference-limited networks in order to improve network throughput. The proposed strategy is distance-aware transmission,...
Cognitive Radios (CRs) are able to operate in a large attribute space and operational parameters are chosen from this space, depending on the sensed environment, to achieve best performance. In this paper we demonstrate that such choice of parameters and the attribute space impact robustness of the network under electronic and information attacks. Such impact results in various tradeoffs to be considered...
Based on an information model that classifies intermediate nodes in multicast networks into network coding, routing and replicating nodes, multicast max-flow and minimum cost optimization frameworks are formulated to solve optimization problems in wireless networks with or without network coding. Two special properties of wireless transmissions are taken into consideration, i.e., multi-hop cooperation...
In this paper we use an analytical model to study how two radio networks : a primary network and a secondary network can coexist within the same area. We use a very simple protocol, Aloha, for both radio networks, and tools borrowed from stochastic geometry to model the performance of our two networks. We show that the primary network and the secondary network can adapt their transmission parameters...
This paper addresses the robust transceiver optimization in multiple-input and multiple-output cognitive radio network, where primary users (PUs) and secondary users (SUs) coexist in the same spectrum band. In the design of cognitive system, the performance degradation perceived by PU should be strictly restricted even with imperfect channel state information (CSI) at cognitive transmitter and receivers...
This paper presents an Equivalent-Figure-of-Merit (EFOM) for designing and evaluating a wireless system towards low power and high performance. Relevant factors like delay, minimum latency, overhead length of a package, package length, data rate, bit-error-rate (BER), pre-receiving time of the receiver, average duty cycle and electronics performance factor are synthesized within a unique model. Comparing...
This paper studies energy and throughput performance of cooperative routing in wireless networks that support cooperative beamforming at the physical layer. Cooperative beamforming is a form of cooperative communication in which multiple nodes each equipped with a single omnidirectional antenna coordinate their transmissions in such a way that the individual signals constructively combine at the intended...
In this paper, an innovative scheduling scheme is proposed for interference-limited wireless multi-hop networks with non-deterministic fading channels. The scheduling problem is considered as a network utility maximization(NUM) problem subject to link rate constraints. With jointly considering link scheduling and the statistical variations of both signal and interference power, the convex sets for...
We address the problem of maximizing the throughput for network coded multicast traffic in a wireless network in the bandwidth limited regime. For the joint scheduling and subgraph selection problem, we model valid network configurations as stable sets in an appropriately defined conflict graph. The problem formulation separates the combinatorial difficulty of scheduling from the arising optimization...
This paper deals with the weighted sum rate maximization problem in wireless networks consisting of multiple source-destination pairs. Since the optimization problem is non-convex, there are multiple local maxima. Here, we propose a simple iterative power control algorithm, namely round-robin (RR) power control, which has a low computational complexity. By comparing against benchmark problem instances,...
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.
We consider the utility maximization problem in wireless multi-hop networks with unicast and multicast communication and jointly optimize routing or network coding together with the physical layer. Since for any communication demands the performance is predominately determined by the region of achievable rates on edges between nodes, we provide a framework for including advanced physical layer methods...
Optimal power allocation for multi-user amplify- and-forward wireless relay networks in which multiple source-destination pairs are assisted by a set of relays is investigated. Two relay power allocation strategies based on maximization of either i) the minimum rate among all users or ii) the weighted sum of rates are developed. A distributed implementation of the maximum weighted-sum-rate power allocation...
The issue of non-cooperative transceiver optimization in the uplink of a multiuser wireless data network with widely linear detection at the receiver is considered in this paper. While previous work in this area has focused on a simple real signal model, in this paper a baseband complex representation of the data is used, so as to properly take into account the I and Q components of the received signal...
Recently there is a growing interest in providing and improving radio coverage for mobile phones and WLANs inside buildings. The need of such coverage appears mainly in office buildings, shopping malls, train stations where the subscriber density is very high. The cost of cellular systems and also the one of indoor wireless systems depend highly on the number of base stations required to achieve the...
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