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This paper investigates the optimal number of collaborating secondary users which can minimize the total error rate (i.e., the summation of probabilities of missed detection and false alarm) for cooperative spectrum sensing when the secondary users follow Poisson point process (PPP). The received signal-to-noise ratios (SNRs) at secondary users can vary since the practical locations and the amount...
This paper introduces a novel bi-directional signaling scheme for decentralized beamformer design to maximize the weighted sum rate (WSR) of multi-cell multi-user multiple-input multiple-output dynamic time division duplexing (TDD) system. In particular, the base stations are assumed to be either in uplink or downlink state based on the instantaneous traffic demand. The WSR maximization problem is...
This work demonstrates the distributed joint selfoptimization of power and decoding order, to alleviate uplink intercell interference in a heterogeneous network, with signal to interference ratio constraints. This problem can be formulated as a potential game of coupled action space among the basestations. However, best response dynamics of this game require global channel knowledge at all cells....
This paper reports a demonstration of high speed visible light communications using a blue laser diode combined with a remote phosphor. This method both generates white light and supports multi Gb/s communications. Data rates of up to 5.62 Gb/s and 6.52 Gb/s were achieved by using OFDM with fixed-rate and adaptive loading approaches, respectively. A total data rate of 10 Gb/s was found to be achievable...
Network virtualization techniques allow for the coexistence of many virtual networks hosted in a same substrate network. Virtual router migrations allow for resource consolidation with the consequence to reduce the power consumption in low traffic periods. Unfortunately virtual router migrations have the effect of degrading the Quality of Service during the downtime in which the router is not able...
The dynamic stochastic resource optimization problem in heterogeneous cloud radio access networks (H-CRANs) is researched in this paper, characterizing the cooperative beamforming with fronthaul capacity and queue stability constraints. To make the average energy efficiency (EE) of remote radio heads (RRHs) arbitrarily close to the optimum and maintain system queue stability, the EE optimization problem...
Electric vehicle (EV) charging and discharging management is an essential component of the smart grids, especially in microgrids due to the high dependence on the local energy sources. In order to provide EV users with freedom to charge and travel, we propose a dynamic scheduling algorithm that does not require EV users to inform their charging time to the control center. The proposed algorithm serves...
One of the major enabler for future wireless communication technologies is spectrum sharing, allowing to effectively share spectrum portions among different services. Even if much more considered in wireless terrestrial communications, spectrum sharing is increasing importance also in satellite communications where the spectrum scarcity issue is arising; cognitive techniques are a promising tool to...
This paper studies the eigenvalue decomposition (EVD) based uplink channel estimation in multi-cell massive multi-input multi-output (MIMO) networks. The performance of the conventional EVD-based channel estimators is limited by the interference from other users in the network due to finite number of antennas and finite transmit samples. We propose an iterative optimization procedure with multiple...
Vehicular communications have gained momentum as a means to coordinate vehicular traffic by disseminating information about the road status and traffic conditions. However, over the time, vehicular applications have changed towards being driven by exchanging and accessing multimedia information. Such applications have therefore evolved and become very greedy in terms of transmitted traffic and used...
In this paper, joint sensor localization and synchronization in non-cooperative wireless sensor networks (WSNs) using time-of-arrival (TOA) measurements is studied. In addition to zero-mean errors in TOA measurements we consider other sources of error such as non-line-of-sight (NLOS) propagation and anchor uncertainty to make our technique more useful in practice, where the presence of these errors...
Ultra network densification and Massive MIMO are considered major 5G enablers since they promise huge capacity gains by exploiting proximity, spectral and spatial reuse benefits. Both approaches rely on increasing the number of access elements per user, either through deploying more access nodes over an area or increasing the number of antenna elements per access node. At the network-level, optimal...
We consider user activity estimation for on-off random access in multi-base station systems. With on-off random access, each user, at a fixed slot, transmits its unique codeword (and is hence active) with probability p, and is heard by all base stations in its vicinity; the goal for each base station is then to determine which of the users in its coverage region are active. This problem models various...
We consider new Dynamic Network Architecture (DNA) which provides significant soft capacity in the network enabling a wide range of adaptations to traffic demand variations without any change in the fixed network infrastructure. To maximize the system throughput we propose a new second order cone programming (SOCP) based algorithm to optimize jointly the access point (AP) selection and the downlink...
In this paper, we introduce new solutions to handle real-time video traffic, such as video conferencing, in the future software-defined radio access networks. The real-time video is well-known for its high peak-to-mean rate ratio. This is a major challenge for traffic engineering and radio resource allocation, especially in small cell radio networks. We first propose an online method to dynamically...
The achievable rate region of a K-user Gaussian multiple access channel (GMAC) is well known. Several schemes have been proposed to achieve some points in this region with minimal encoding and decoding complexities such as successive interference cancelation and successive integer forcing. But these schemes require coordination among the nodes or with the base station for choosing the rates of transmission...
In this study, optimal jamming of wireless localization systems is investigated. Two optimal power allocation schemes are proposed for jammer nodes in the presence of total and peak power constraints. In the first scheme, power is allocated to jammer nodes in order to maximize the average Cramér-Rao lower bound (CRLB) of target nodes whereas in the second scheme the power allocation is performed for...
Network localization is a key feature in many wireless services and applications. In typical rang-based localization techniques, “agents” try to perform position estimation through ranging with respect to “anchors” with known positions. Based on the definition of squared positional error bound (SPEB), the localization accuracy can be determined by the transmit power, carrier frequency and signal bandwidth,...
In this paper, we study Two-Way Relaying (TWR) networks well-known for its throughput merits. In particular, we study the fundamental throughput delay trade-off in TWR networks using opportunistic network coding (ONC). We characterize the optimal ONC policy that maximizes the aggregate network throughput subject to an average packet delay constraint. Towards this objective, first, we consider a pair...
In a device-to-device (D2D) communication underlaying cellular network, user equipments are required to operate cooperatively and unselfishly to transmit data as relays. However, most users behave in a more or less selfish way, which makes user selfishness a key factor that affects the performance of the whole communication system. We focus on the impact of node selfishness on D2D communications....
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