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We analyze the characteristics and performance of a wireless ad hoc network where nodes are connected via random channels and information is transported in the network in a cooperative multihop fashion using amplify and forward relay strategy. We characterize the network by studying important parameters such as: (1) SNR degradation with hop, (2) outage probability, (3) maximum permissible number of...
We propose a new method for computing transmit beamforming vectors for downlink multicell multiple- input multiple-output (MIMO) networks. The key novelty of the work is the application of graphical model theory to the intercell interference problem. An index restriction beamforming strategy is adopted to mitigate intercell interference, and is implemented with the well-known message-passing algorithm...
We consider a wireless communication model where a large number of transmitter-receiver pairs share a common Rayleigh fading channel without any coordination between them. The performance of a simple coexistence etiquette is analyzed in details, where packets are allowed to be transmitted from a given terminal only if the signal-to-interference-plus-noise ratio (SINR) at their intended receiver exceeds...
This paper studies the value of allowing multiple transmitters to share all of the available bandwidth to concurrently transmit to a single receiver with multi-packet decoding capability. While such coordination can be bandwidth-efficient, it increases the density of interferers when many such multiple-access clusters exist in the network. On the other hand, orthogonal schemes such as FDMA may not...
Endowing mesh routers with multiple radios is a recent solution to improve the performance of wireless mesh networks. The approaches proposed in the literature to solve the problem how to assign channels to radio have mainly focused so far on reducing interference or maximizing the throughput. To the best of our knowledge, none of such approaches attempted to save network resources for the purpose...
Transmitting request-to-send (RTS)/clear-to-send (CTS) packets at the maximum power and data/ACK packets at the minimum power creates a asymmetrical link which has been proven to increase the collision probability. In this paper, we first discuss the deficiency of uncontrolled asymmetrical transmission power in multi-channel environments. We then propose a symmetrical power control for multi-channel...
In this work, we propose a small world model to design Heterogeneous Sensor Networks (HSNs). The proposed model takes into account the communication pattern of this network to create shortcuts directed to the monitoring node, decreasing data communication latency. The endpoints of these shortcuts are nodes with more powerful communication range and energy reserves to support the long communication...
We investigate the dynamic connectivity of cognitive radio ad-hoc networks (secondary networks) coexisting with licensed networks (primary networks) that experience time-varying on-off links. It is shown that there exists a critical density λs* such that if the density of secondary networks is larger than λs*, the secondary network percolates at all time t >; 0, i.e., there exists always an infinite...
Binary power control has been shown to be optimal in a variety of network conditions. In the context of sumrate maximisation in interference networks, our main result states that the optimal power policy for a link is binary if it only interferes with one other link in the network. Examples of networks which have at least one link with this attribute include the two-link interference channel (IC),...
One of the important challenges that still exist in Wireless Mesh Networks is the capacity reduction due to interference of wireless links. In order to improve throughput of wireless mesh networks each node is equipped with multiple interfaces and can use multiple channels simultaneously. Important issue in these networks is efficient channel assignment so that it minimizes interference. In this paper,...
Multipath routing has been a promising solution to improving reliability and system throughput for wireless mesh networks. However, existing schemes designed for system throughput improvement suffer the route-coupling problem (i.e., the determined multiple paths originating from the same source node typically stay very close to the shortest path to the gateway) so that the improvement ratio may not...
This paper investigates the performance effects of packet depletion on multihop wireless networks. The resulting capacity usage inefficiencies of link assigned schedules are shown even at the maximum supportable uniform network load. Hybrid node-link assignment is employed to extend transmission rights, allowing nodes to transmit on sets of reserve links when the primary scheduled link experiences...
Characterizing the topology and therefore fundamental limits is a must to establish effective end-to-end cognitive radio networking (CRN). However, there lacks complete understanding of the relationship among connectivity, interference, latency and other system parameters of the CRN. To clarify this complication, by employing tools from both percolation theory and stochastic geometry, we thus provide...
We present a distributed joint power control and transmit beamforming selection scheme for multiple antenna wireless ad hoc networks. Under the total network power minimization criterion, a joint iterative beamforming and power control algorithm is proposed to reduce mutual interference at each node. Total network transmit power is minimized while ensuring a constant received signal-to-interference...
In wireless sensor networks, the nodes near the sink suffer from heavy traffic load. The recent progresses in physical layer make multi-packet reception (MPR) feasible, which may alleviate the suffering nodes. In this paper, we utilize MPR to improve the throughput of wireless sensor networks while maintain the fairness requirement for each sensor. Firstly, we formulate an optimization problem for...
In this paper, we introduce a distributed dynamic routing algorithm for secondary users (SUs) to minimize their interference with the primary users (PUs) in multi-hop cognitive radio (CR) networks. We use the medial axis with a relaxation factor as a reference path which is contingent on the states of the PUs. Along the axis, we construct a hierarchical structure for multiple sources to reach cognitive...
In this paper, we propose a link outage probability based resource allocation scheme for multi-radio multi-channel wireless mesh networks. The objective is to optimize the link outage probability under the effect of channel variation and external interference while preserving the end-to-end traffic demand requirements. The problem is formulated as a mixed-integer nonlinear programming problem, which...
In this paper, we propose a new method, called Load-Aware Channel Assignment Exploiting Partially Overlapping Channels (Load-Aware CAEPO), which uses not only non-overlapping channels but also partially overlapping channels. We further improve our scheme by introducing the concept of node grouping to enhance the performance, and develop another new channel assignment algorithm called Load-Aware CAEPO-G...
Single-radio mesh routers operating on a single channel suffer from low throughput due to collisions. Equipping mesh routers with multiple radios operating on non-overlapping channels can significantly improve the throughput. However, the assignment of channels to radios in a multi-radio mesh network is a challenging task. In this paper, we propose a channel assignment algorithm, TICA (Topology-controlled...
Previous research on physical layer network coding (PNC) focuses on the improvements in bandwidth usage efficiency. In this paper, we propose a PNC-based node localization mechanism. When two signal sequences collide at the receiver, the starting point of collision is determined by the distances between the receiver and senders. When the signal interference results from two receivers are combined...
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