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In this article, we develop a unified framework for characterizing the area spectral efficiency and the energy efficiency (EE) of multi-antenna multi-hop cognitive underlay networks (CRNs). We highlight the available degrees-of-freedom which can be exploited to maximize the EE of the network. In particular, we demonstrate that considering the primary user's quality of service (QoS) requirements, joint...
The recent digital transition of TV broadcasting has created new opportunities for wireless usage for voice, video and data services in these newly released bands (known as TV white spaces). Some possible wireless technologies that can be deployed in this new spectrum are LTE and Wi-Fi. In this paper, we conduct an in-depth analysis of the physical layer performance of LTE and Wi-Fi in the presence...
In wireless mesh network, resource & bandwidth allocation is important for achieve efficient and collision-free rate transmission. Therefore, the wireless mesh network standard e.g WiMAX defines three scheduling mechanisms to schedule time resources in the mesh mode, all of those algorithms are based on time division multiple access (TDMA), such that coordinated centralized scheduling, coordinated...
Long Term Evolution (LTE) is treated as a mainstream wireless communication technology from the 3G to 4G. The Orthogonal Frequency Division Multiple Access (OFDMA) is introduced to solve the innercell interference in the downlink of LTE. However the intercell interference especially for the edge users is still remain unsolved. In this paper, we propose a novel and general interference coordination...
In this work we propose a variation to the Block Diagonalization (BD) algorithm described that mitigates the interference from an external interference source which does not participate in the joint transmission inherent to the BD algorithm. The idea consists of precoding the signal at the transmission side so that the received signal at each receiver lies in a subspace orthogonal to the subspace...
Cognitive radio is an exciting emerging technology that has the potential of dealing with the stringent requirement and scarcity of the radio spectrum. Such revolutionary and transforming technology represents a paradigm shift in the design of wireless systems as it will offer the ability of radio sensing, self adaptation and dynamic spectrum sharing. In this paper, we are interested in the case where...
In this paper, we develop an energy efficient cross-layer design which optimally combines Adaptive Modulation (AMC) and Coding and Power Control (PC), at the physical layer, with type-I Hybrid Automatic Repeat reQuest (HARQ-I) protocol, at the data link layer. The objective is to maximize the average throughput efficiency under a prescribed average transmit power constraint. We have shown in [7] that...
In this paper, we propose a green radio resource allocation (GRRA) scheme for LTE-A downlink systems with coordinated multi-point (CoMP) transmission to support multimedia traffic. It is a crucial issue to find a balance between throughput maximization and transmission power minimization, especially when the QoS requirement guarantee for multimedia traffic is considered. The GRRA scheme defines a...
Multiple Transmit and receive antenna are now widely used to form multiple input., multiple output (MIMO) channels to increase the capacity as well as to reduce the Bit Error Rate (BER). This paper describes the combination of MIMO system along with Orthogonal Frequency Division Multiplexing (OFDM) system which offers important features of both the system. Use of Hybrid MIMO-OFDM system is considered...
In this paper, we propose an improved utility-based radio resource allocation algorithm in orthogonal frequency division multiple access (OFDMA) wireless networks. The queue state information (QSI), channel state information (CSI), QoS requirements and transmitted packets are synthetically considered in the utility function, thus it can meet the needs of networks with multi-service better. Based on...
Increasing data demand started to become a common challenge in mobile cellular networks. Various techniques, intelligent approaches and network architectures are being developed to tackle this difficulty, in order to provide high quality of service and to allocate mobile resources effectively. Adaptive modulation and coding is one of those techniques, that provides high quality of service while adapting...
Long Term Evolution (LTE) supports closed-loop MIMO techniques to improve its performance, but in order to exploit multiuser MIMO channel capabilities, the design of an efficient MAC scheme that supports Multiuser MIMO is still an open issue in the literature. This paper proposes a novel energy efficient MAC scheme for LTE, which aims to achieve simultaneous downlink transmissions to multiple users,...
An orthogonal modulation enabled two-phase energy-efficient framework is presented for active cooperation between secondary users (SUs) and primary users (PUs) in a cognitive radio network. Since the PU has higher priority, and SUs compete for spectrum accessing, we model the power control problem as a Stackelberg game which incorporates throughput and energy consumptions into utility design. Due...
In the last years we are seeing the increasing presence of multimedia applications together with a wide variety of terminals, from the PCs to the notebooks, from the smartphones to the tablets. In order to exploit such advanced services, ubiquitous and broadband connections are required. While urban or suburban areas can be covered by using terrestrial wireless broadband networks, there are several...
In this paper, we propose a novel multihop transmission scheme using selective network coding (NC) and differential modulation (SNC-DM) for two-way relay networks (TWRNs) when neither the source nodes nor the relay nodes know the channel state information (CSI). We first develop a bidirectional transmission scheme using NC where the information exchange in a two-way multihop relay network with the...
Future wireless communications will face the dual challenge of supporting large traffic volume while providing reliable service for various kinds of delay-sensitive traffic. In light of this challenge, this paper investigates the throughput performance of a wireless communication system under channel coding over finite “packets.” When we apply coding over multiple “packets,” the underlying wireless...
In this work a sphere decoder with low complexity is proposed and implemented. We propose a simplified norm algorithm, which is called admissible set elimination (ASE), to dramatically decrease the number of searching nodes. In addition, the decoder uses table-look-up to acquire the enumeration order of different constellations. As a result, the critical path is shortened and the throughput is enhanced...
The increased demand on data and the scarcity of available bandwidth motivate research for new technologies beyond 4G. In this paper we provide a system level study of a new cellular architecture that incorporates millimeter wave technology (60 GHz) for the access link. A system level simulation is carried out for a university campus and an urban environment and the sensitivity to various design parameters...
Virtual Multiple-Input Single-Output (vMISO) systems distribute multi-antenna diversity capabilities between a sending and a cooperating node. vMISO has the potential to vastly improve wireless link reliability and bit error rates by exploiting spatial diversity. In this paper, we present the first design and experimental evaluation of vMISO triggers (when to invoke vMISO rather than traditional transmission)...
Cooperative packet recovery has been widely investigated in wireless networks, where corrupt copies of a packet are combined to recover the original packet. While previous work such as MRD (Multi Radio Diversity) and Soft apply combining to bits and bit-confidences, combining at the symbol level has been avoided. The reason is rooted in the prohibitive overhead of sharing raw symbol information between...
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