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Recently, a strong demand on high data rate wireless communication can be observed. The development of multi-gigabit wireless transmission systems has become very attractive. For achieving such data rates, the exploitation of 60 GHz mm wave is a very promising technical approach and has been adopted in IEEE 802.15.3c. Except for physical layer (PHY) designs, the Medium Access Control (MAC) layer design...
Reducing the consumed energy in wireless communication systems has a direct impact on operational expenditure as well as CO2 emissions. With increasing interest in multimedia applications and high data rate services, environmentally sustainable communications networks must reduce the energy per delivered bit at an equal rate, if not better. This paper addresses downlink energy-efficient transmission...
In this paper, we apply distributed optimization dynamics of the mutually connected neural networks to RAN selection in heterogeneous type cognitive wireless networks. We evaluate the performance of the proposed approach by implementing it on an experimental heterogeneous wireless network system called Cognitive Wireless Cloud, which supports vertical handover between different radio access networks...
In this paper, we propose a precoder using a minimum mean-square error (MMSE) criterion for a non-regenerative relay system. It is assumed that the relay knows the channel covariance information (CCI) of the relay-destination link and the full channel state information (CSI) of the source-relay link. We start by assuming the precoder has a specified structure. We derive an upper-bound of the mean-square...
In this paper, we present a novel application of matrix game theory for optimization of link scheduling in wireless ad-hoc networks. Optimum scheduling is achieved by soft coloring of network graphs. Conventional coloring schemes are based on assignment of one color to each region or equivalently each link is member of just one partial topology. These algorithms based on coloring are not optimal when...
The information and communications technologies world is migrating towards the Future Internet (FI) era. Operators will have increased complexity to address in the FI era, compared to today, in the management of their infrastructure and services. This is due to the extended set of applications that should be supported and to the more options offered by the infrastructure. Cognitive management systems...
In this work we consider the allocation of buffer space to data streams sharing a common high-speed wireless transmitter. As an example, we focus on an OFDMA-based downlink system scenario. Scheduling for maximum throughput has been extensively studied in the literature. However, the practically interesting case of a finite buffer has not been sufficiently addressed before. Especially in the case...
Cell phone battery life has been a fundamental design consideration ever since the first mobile devices were introduced in the 1970's. When mobile services were restricted to voice, the problem from a system design perspective often boiled down to finding best of breed components (e.g. amplifiers, signal processors, etc.) that optimized power while not sacrificing size. However, today's cell phones...
Wireless sensor networks consist of various sensor nodes which operate in a memory, energy and bandwidth constrained environment. Target tracking is an important application in wireless sensor networks and in this paper we propose an energy aware target tracking (EATT) algorithm. Energy efficiency is obtained due to the novel concept of tracking being performed in a collaborative manner by different...
In this paper we develop a discrete and distributed optimization framework that maximizes the overall spectral efficiency of heterogeneous networks while ensuring a minimum fairness among users. We split the problem into two subproblems: the first one is handled by the users and consists in a transmission by each user of a minimum rate requirement to the base stations and the second is the resource...
We propose advanced compressive estimators of doubly dispersive channels within multicarrier communication systems (including classical OFDM systems). The performance of compressive channel estimation has been shown to be limited by leakage components impairing the channel's effective delay-Doppler sparsity. We demonstrate a group sparse structure of these leakage components and apply recently proposed...
We consider cooperative relaying systems employing amplify-and-forward (AF) distributed space-time block codes (DSTBCs) in which only backward channel-state-information (CSI) is known at relays and destination. For such systems, we study the particular case where, in order to minimize overhead, each of N relays decide independently whether to join the cooperation with basis on the received signal...
We address an opportunistic subchannel scheduling problem in relay-based OFDMA cellular networks. In most previous works on relay-based cellular networks, immediate relaying at relay stations (RSs) was assumed, without allowing the opportunistic scheduling at RSs. Hence, each RS should transmit the received data from the base station (BS) to the corresponding mobile stations (MSs) immediately within...
We study a problem where wireless service providers compete for heterogenous and atomic (non-infinitesimal) wireless users. The users differ in their utility functions as well as in the perceived quality of service of individual providers. We model the interaction of an arbitrary number of providers and users as a two-stage multi-leader-follower game, and prove existence and uniqueness of the subgame...
In this paper, an efficient scheme to optimize resource allocation for dynamic OFDMA based WiMAX systems is presented, which provides priority estimated resource allocation with individual QoS provisioning. Our proposed scheme dynamically assigns OFDMA resources to the users to optimize the overall system performance in heterogeneous traffic and diverse QoS based WiMAX systems. To achieve this goal,...
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