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Total relay transmit power minimization in Amplify-forward (AF) MIMO relay beamforming is naturally formulated as an indefinite quadratic (nonconvex) program and then semidefinite relaxation (SDR) technique can be used to locate their optimal solutions. Indeed, SDR often gives rank-one optimal solution within a low number of relaying antennas and communicating users. However, as the antennas number...
Current 3GPP specifications for LTE include the use of MIMO as a key technology. MIMO can be seen from two different perspectives: if increased data rates are targeted, for a given value of SNR, one gets improved data transmission; however, from an energy efficiency viewpoint, lower values of SNR are needed for the same reference data rate, therefore, allowing the reduction of the transmitted power,...
In this paper, we propose a hybrid division cooperative transmission (HDCT) scheme for system throughput enhancement in enterprise femtocell systems. In HDCT scheme, a cooperative transmission (CT) scheme is applied to user equipments (UEs) located at the edge of a serving femtocell base station (fBS), whereas conventional scheme is applied to UEs located near the fBS. In the zone where CT is applied,...
In this paper, we investigate the performance of adaptive modulation in spectrum sharing cognitive relay networks, where the secondary user (SU) transmits the message by one best relay with amplify and forward (AF) relaying scheme. Moreover, to guarantee the primary user (PU)'s transmission quality, the interferences caused by the SU transmitter and the selected relay are less than a predetermined...
Mobile ad-hoc networks (MANETs) are a key enabler of pervasive computing. Constrained resources in mobile stations make it critical for nodes to be able to cooperate to enhance communication and computation capabilities. However, the wireless and dynamic nature of the links presents easy attack vectors for adversaries. The ability to securely discover and identify neighboring nodes (secure ND) is...
A simulation study on the downlink signaling performance of intra-LTE intra-frequency mobility load balancing in the macro-cellular context will be presented in this paper. The results identify the HO command message as the most critical signaling message. In addition the range of the cell individual offset for different UE speeds and signaling error thresholds will be identified.
Since the standardization of Long Term Evolution — Advanced (LTE-A) is currently carried through in 3rd Generation Partnership Project (3GPP), it is of great importance to ensure the coexistence between LTE-A system and other mobile systems. This paper is aiming at presenting the performance loss of 3G/B3G TDD systems (TD-SCDMA, TD-HSDPA and TD-LTE) interfered by LTE-A system. The detailed interference...
In cognitive radio, cooperative detection through optimization can improve the performance of spectrum sensing. In this paper, the optimal selection of cognitive radios including threshold optimization and cognitive radio's selection optimization is proposed, and the sensing mechanism including sensing period optimization and sensing time optimization is also analyzed. The proposed optimization algorithm...
We propose a joint bit and power loading, beamforming, multiple base station set (MBS) selection and subcarrier allocation algorithm for a resource allocation problem in a uplink multicell coordinated multi-basestation reception system. The objective is to minimize the total transmit power with rate constraint per mobile station (MS). The resources that we are considering include power, subcarrier,...
In this paper, we propose a novel CRN MAC, called MAX-PS-MAC. MAX-PS-MAC uses a probabilistic channel assignment mechanism that attempts at maximizing the packet success probability of each transmission by exploiting statistical information regarding availability durations and link quality conditions of idle channels. While most of previously proposed CRN MAC protocols account for PR channel dynamics...
This paper is concerned with the study of confidential communication through independent and identically distributed (i.i.d.) and evenly correlated Rayleigh fading channels, where a single antenna transmitter communicates with the corresponding receiver in the presence of an eavesdropper. Both the receiver and eavesdropper are equipped with multiple antennas and employ diversity combining receptions...
LTE-Advanced adopts relay deployment to support higher data rates and better coverage, especially at the cell edges which suffer from inter-cell interference. The solution of relaying is attractive because of its low cost and easy deployment. In this paper, we show that deploying just two relays per sector can significantly improve system capacity and coverage. We optimize the geometric deployment...
Deploying relay nodes is foreseen a cost-efficient solution to combat the severe propagation loss at cell edge. However, relay cell coverage is limited by the low transmit power, limited antenna capabilities and wireless backhaul link bottleneck which may lead to load imbalances and hence low resource utilization efficiency. Further challenges in relay deployments are attributed to increased interference...
Relay nodes (RN) have been suggested to be placed near the edge of a cellular network in order to improve link qualities of cell edge user equipments (UEs). Compared to conventional homogeneous networks, system performance for the relay-enhanced network can be significantly degraded if handovers between the RNs and evolved node base-station (eNB) are not correctly and immediately determined by the...
Relay Based Cellular Networks (RBCNs) are a key development in cellular networking technology. However, because of ever increasing demand and base station failure, RBCNs still suffer from user congestion and low resilience problems. This paper proposes two competing solutions: dynamic frequency allocation and antenna tilting to those problems. Firstly a new dynamic fractional frequency allocation...
We propose a new network model framework, denoted heterogeneous fluid model network, which allows to derive closed formula for the Signal to Interference plus Noise Ratio (SINR) received by a mobile in heterogeneous cellular networks, composed of macro cells and femto cells. Quality of service (QoS) and performance of wireless networks can therefore be analyzed in a simple way. We apply our model...
This paper develops a new expression for a network node capability value used to quantify the node's ability to maintain an optimal information flow in a mobile communication network. The capability value is adaptable and is a function of the bandwidth efficiency, the data rate, the energy-per-bit to noise spectral density power ratio and reflects how effectively the node can receive, process and...
Wireless cellular communication networks is undergoing a transition from being a simply optional voice communication to becoming a necessity in our everyday lives. In order to ensure uninterrupted high Quality of Experience for subscribers, network operators must ensure 100% reliability of their networks without any discontinuity either for planned maintenance or breakdown. This paper demonstrates...
Femtocells constitute an economical solution conceived for improving the indoor coverage, which are capable of achieving a high network capacity. In order to guarantee a high Area Spectral Efficiency (ASE), femtocells have to reuse the spectrum of macrocells. As a result, the performance of both the femtocells and macrocells may suffer owing to the near-far effects. In this paper, we investigate the...
Passive source localization has been the focus of considerable research efforts due to its usefulness in various applications. This paper performs a fundamental investigation of whether the gain ratios of arrival (GROAs) can be utilized in conjunction with the range differences of arrival (RDOAs) to improve the multiple sources localization accuracy in the presence of sensor location uncertainties...
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