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A major challenge in wireless sensor networks (WSN) is that spatially distributed nodes need to achieve a global task in a completely decentralised manner. Motivated by the fact that optimisation problems in WSNs can often be formulated as Markov random field (MRF) energy minimisation, a general MRF-based framework for the design of distributed WSN algorithms was proposed recently. Building upon this...
Online social search (OSS) brings forth a new way to harness the Internet for answers. In this paper, we study the non-cooperation problem in OSS. We propose an analytical model that captures the behavior of OSS nodes, and, from a gaming-strategy point of view, analyze various strategies an individual node can utilize to allocate its awareness capacity. Based on this we derive the Pareto inefficiency...
In this paper, we consider an optimal power allocation scheme for a physical layer network coding relay based secondary user (SU) communication in cognitive radio networks. SUs are located on two different primary user (PU) coverage areas and we introduce an energy and spectrally efficient SU communication scheme. The sum rate of relay based two way communications for SUs is maximized under a total...
In this paper, we investigate Sybil attacks on spectrum allocation in distributed dynamic spectrum access (DSA) networks. Using IEEE 802.11 devices as secondary nodes, we demonstrate the feasibility of mounting Sybil attacks in the cognitive radio testbed, in which the malicious node poses as multiple normal secondary nodes with different identities in order to steal more spectrum bands. We also show...
In this paper, we develop a cross-layer algorithm to minimize energy consumption in multi-hop wireless networks with finite buffers. Our algorithm guarantees a flow-based minimum data rate and a deterministic buffer size upper-bound for individual flows at network nodes. The algorithm jointly integrates congestion control, power allocation, routing and link rate scheduling. In addition, the algorithm...
This paper addresses the problem of interference coordination in relay-aided cellular OFDMA systems, aiming at exploiting the benefits of RNs while minimizing the negative effects of interferences introduced. We first analyze the possible interference scenarios in multi-cell OFDMA systems. Based on the insights in our analysis, we propose an Integrated Interference Coordination Scheme (IICS) for cellular...
In this paper, we consider a two-way relay network (TWRN) employing amplify and forward (AF) relaying protocol and design a near optimal AF scheme to minimize the sum bit error rate (BER) of two end users. For the considered TWRN, in the first two time slots, each user respectively broadcasts its message to both the relay and the other user. Then, the relay linearly combines two received signals and...
With the rapid advance in the technology area of data storage, storage capacities have increased substantially while the price has been dropping fast. Motivated by this trend, it has been proposed in the Cache-and-Forward architecture that storage is incorporated into each intermediate CNF router. Content can be cached at CNF routers when they flow through the network, and therefore, routers can serve...
In this paper, we propose a relay selection amplify-and-forward (RS-AF) protocol in general bi-directional relay networks with two sources and relays. In the proposed scheme, the two sources first transmit to all the relays simultaneously, and then a single relay will be selected to broadcast the received signals back to both sources to achieve a minimum sum symbol error rate (SER). To facilitate...
Recently, the OFDM-based Spectrum-sliced Elastic Optical Path (SLICE) network attracts significant interests due to its elastic band-width allocation. The OFDM technology, on one hand, enables both sub-wavelength and super-wavelength traffic accommodation by allocating appropriate number of sub-carriers. On the other hand, it can provide high signal quality by overcoming various impairments. In SLICE...
In this paper, we consider an opportunistic access to the spectrum resources in wireless networks. The resources are adopted by the network nodes in a distributed manner, i.e. based on their local channel quality information. The competition of nodes for available resources is modeled as a game. To coerce the desired behavior of the competitors having no information on the other players, pricing (taxation)...
Network virtualization has been recognized as a promising solution to enable the rapid deployment of customized services by building multiple Virtual Networks (VNs) on a shared substrate network. Whereas various VN embedding schemes have been proposed to allocate the substrate resources to each VN requests, little work has been done to provide backup mechanisms in case of substrate network failures...
In this paper, we propose a dynamic power allocation scheme for a single-relay network based on orthogonal frequency division multiplexing (OFDM) modulation with limited feedback.We consider an Amplify-and-Forward (AF) cooperative diversity model, where one source node communicates with one destination node assisted by one half duplex relay. The power allocation scheme employs a codebook of quantized...
In this paper, joint optimization of subcarrier pairing, relay selection and power allocation is formulated through a capacity maximization problem in orthogonal frequency division multiplexing (OFDM) relay systems, with fairness considerations and individual power constraint on each node. Because achieving the optimal solution is computationally demanding, which is resulted from the excessive possibilities...
In this paper, we propose a distributed joint relay selection and power allocation scheme in wireless multi-hop cooperative networks, taking both instantaneous channel state information (CSI) and relay nodes' residual energy into consideration. Specifically, we formulate the cooperative relaying network as a restless bandit system, which has been successfully applied in stochastic control and operations...
This paper investigates the optimal power routing problem in relay-based cooperative networks, where the relays are arbitrarily positioned. We generalize the standard shortest path routing algorithm (GSPRA) to find an minimum-power distributed MIMO multi-hop route from a source to a destination while satisfying a given e2e outage probability demand. The task of the proposed approach includes how to...
The cooperative information aggregation (CIA) scheme for distributed estimation was proposed in our past research considering the realistic wireless sensor network (WSN) environments. In the existing CIA scheme, a multi-bit quantizer is applied at all nodes, however, each node only transmits one predetermined bit of its quantized observation to the fusion center (FC) to economize the energy expense...
Energy minimization in wireless sensor networks is a key issue, particularly in order to maximize the lifetime of nonserviceable battery powered devices in the field. In this paper, we propose a new energy consumption model that allows allocation of variable transmit power and data compression/transmission rate to each sensor node. In contrast to previous work, our model captures both the cost of...
Relay selection has been shown to be a practical and effective way to achieve cooperative diversity. In wide-band OFDM cooperative communication systems with multiple source and destination nodes, however, the best relay selection and subchannel allocation has not been studied in a systematic way. In this paper, a random combinatorial optimization approach, referred to as the random bipartite graph...
In this paper, we investigate the optimal precoding scheme for relay networks with finite-alphabet constraints. We show that the previous work utilizing various design criteria to maximize either the diversity or the transmission rate with the Gaussian inputs assumption may lead to significant loss for a practical system with finite constellation set constraint. A linear precoding scheme is proposed...
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