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Ultra-wideband (UWB) transmission is an emerging wireless communication technology that is gaining significant interest for future broadband wireless access. This transmission technique based mainly on the Impulse-Radio (IR) paradigm, has the potential to deliver high-speed wireless connectivity at low power and low proximity, characteristics that makes it an ideal choice for wireless sensor networks...
In this paper we address the problem of two-way communication in multiple peer-to-peer relay networks, with perfectly known channel state information. Herein, multiple terminal transceiver nodes in the network are organized into two groups, and transceivers in each group want to simultaneously conduct bidirectional communications with their respective peers in the other group through the assistance...
The prime focus of this work is in describing a symbiotic architecture for a Cognitive Radio network, called Cognitive Relaying with Frequency Incentive. The incumbent Primary User (PU) of the spectrum, with a weak transmission link, seeks cooperation from the cognitive Secondary User (SU) nodes in its vicinity, and in return rewards them with incentive frequency bands for their own communication...
We introduce closed-form lower bounds for the performance of multi-hop wireless networks with non-regenerative relays over Rayleigh fading channels in the presence of co-channel interference. The analysis assumes an arbitrary number of independent and identically distributed Rayleigh interferers. Novel closed-form expressions are obtained for the probability density function (PDF) and cumulative distribution...
We propose a close-to-capacity dirty-paper coding framework which employs multi-level low density parity-check (LDPC) and trellis coded quantization. The proposed coding framework is robust in the sense that it performs close to capacity in the high as well as the low rate regimes. This is in contrast to existing practical DPC schemes which perform well at one of these regimes, but never both. In...
In this paper, we examine the problem of channel assignment in multi-hop wireless networks in which each node is equipped with multiple transceivers. We summarize various approaches to transceiver channel assignment. Most approaches in the literature seek to assign a channel to each available transceiver. In contrast, we seek to achieve a baseline connected topology that conserves resources, keeping...
In cognitive radio networking, the signal reception quality of a secondary user degrades due to the interference from multiple heterogeneous primary networks, and also the transmission activity of a secondary user is constrained by its interference to the primary networks. It is difficult to ensure the 1-connectivity of the secondary network, so we here characterize the connectivity of the secondary...
A physical-layer network coding (PNC) aided twoway relay scheme is proposed for Transmitted-Reference (TR) UWB networks. In particular, a novel noncoherent UWB-PNC detector is investigated for the TR UWB networks. Inheriting the simplicity of the TR-UWB receiver, the proposed PNC detector is based on the autocorrelation receiver (AcR) with simple structure, which effectively suppresses the multi-user...
Network coding is known to be a promising technology to increase the bandwidth capacity in wireless networks. To our best knowledge, there is limited work on studying the available bandwidth for a given path with network coding. This paper presents a new method to estimate the available bandwidth of a path that considers network coding and wireless interference simultaneously. We show that our estimated...
End-to-end delay is an important QoS metric in sensor networks as well as any application that involves transferring of small-sized files. In this paper, we address how to minimize the end-to-end delay in a multihop wireless network. End-to-end delay is defined as the total time it takes for a single packet to reach the destination. It is a result of many factors including the length of the routing...
Distributed spectrum allocation in Cognitive Radio (CR) systems requires each Secondary User (SU) to learn the optimal spectrum policy which maximizes the network performance while minimizing the impact to the Primary Users (PUs). To this aim, each SU must rely on local sensing information which however can be biased by interference and fading effects on the received signal. Thus, if each SU works...
The essence of spectrum allocation is to find an appropriate distribution of spectrum bands among users so that they can coexist. Thus, spectrum allocation can avoid interference that caused by two interference SUs using the same channel. Different spectrum allocation can lead to different network topologies and consequently have effect on the network connectivity. The aim of this paper is twofold:...
We consider the problem of energy-efficient transmission in multi-flow multihop cooperative wireless networks. Although the performance gains of cooperative approaches are well known, the combinatorial nature of these schemes makes it difficult to design efficient polynomial-time algorithms for joint routing, scheduling and power control. This becomes more so when there is more than one flow in the...
Cognitive radio ad hoc networks (CRAHNs) have become a popular network architecture for connecting mobile nodes thanks to the flexibility and adaptability of such type of network. In this paper, we propose a novel scheme for efficient routing design in CRAHNs. The proposed routing scheme firstly forms a simple directed graph for the given physical network. Using the simple directed graph, multiple...
Secondary users sharing primary users' spectrum is modeled as a graphical game. Users located in random graphs and a regular lattice are considered. Secondary users are assumed to differentiate the ``quality" of the primary spectrum while interacting within their local neighborhood to minimize interference and congestion. The learning algorithm is also shown to be effective in punishing malicious...
A key challenge in cognitive radio networks (CRNs) is how to adaptively and efficiently select a route and assign resources along that route according to the surrounding environment. In this work, we propose a distributed routing protocol for mobile CRNs, in which path selection and resource allocation (e.g., spectrum, transmission power, and transmission rate) are determined by receivers. Because...
Existing works designed for the multi-radio multi-channel (MR-MC) wireless network mainly rely on the orthogonal or non-overlapping channels. But in reality, the limited number of non-overlapping channels is a major issue when the network is dense. In this paper, we study the impact of partially overlapping channels (POC) on the network capacity through computing the maximum achievable capacity in...
In Physical-Layer Network Coding (PNC), the symbol detected at the relay node in two-way relay channels (TWRC) is the superposition of the symbols transmitted by the sinks. We refer to these symbols as pnc-symbols. In traditional modulation constellations such as Quadrature Amplitude Modulation (QAM) and Phase Shift Keying (PSK), the demodulator may fail to optimally identify pnc- symbols formed from...
Heterogeneous networks utilizing relay nodes with low transmission power becomes an important deployment scenario in 4G cellular standards. It can offer high data rate delivery as well as ubiquitous end-user experience. For such a network, an efficient mobile association and load balancing scheme is critical to achieve high system capacity and satisfactory user experience. In this paper, the main...
The scope of this paper is two-fold. First, we extend the concept of transmission capacity of a wireless network to the broadcast scenario and consequently define the broadcast transmission capacity of a wireless network as the product of the spatial density of broadcasting nodes, the average number of neighbors of a broadcasting node, and the information rate, considering both intra-system interference...
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