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In a cognitive relay network (CRN) consisting of multiple pairs of PUs and CUs, the resource allocation issues, specifically, the spectrum and power allocation and relay selection for secondary users (SUs) have to be considered to support efficient spectrum sharing among primary users (PUs) and SUs and providing quality of service (QoS) guarantees for both PUs and SUs. In this paper, we address the...
In this paper, we consider a joint optimization of sensing parameter and power allocation for an energy-efficient cognitive radio network (CRN) in which the primary user (PU) is protected. The optimization problem to maximize the energy efficiency of CRN is formulated as a function of two variables, which are sensing time and transmit power, subject to the average interference power to the PU and...
In this paper, we investigate the problem of optimal power allocation for a two-hop cognitive radio relay network over independent Rayleigh fading channels. We take into consideration of the transmit power limit at the secondary transmitter and relay where the powers are limited to guarantee the quality of service of the primary user. To minimize the secondary outage probability, we re-formulate the...
In order to have escalation in the throughput of LTE-Advanced network, carrier aggregation (CA) is employed for meeting the requirement set by International Telecommunication Union (ITU). Within the context of CA, component carrier (CC) selection and scheduling is the most critical task and has significant impact on the network performance. In this study, we propose a self-organized downlink resource...
An auction-based joint subcarrier and power allocation approach is investigated to improve the performance of device-to-device (D2D) communication underlay cellular networks with uplink (UL) resource sharing. To maximize the system sum rate over the resource reuse of multiple D2D pairs, we introduce a reverse iterative combinatorial auction to formulate the optimization problem. In the auction, cellular...
In the heterogeneous cellular network, each mobile station perceives different channel gains to different base stations. Therefore, it is important to associate a mobile station with the right base station with transmit power control so as to achieve substantial improvement in spectrum-efficiency and energy-efficiency. Despite its importance, the problem that maximizes the overall system revenue with...
The performance of multi-channel (MRMC) wireless mesh networks (WMNs) is largely affected by interference, which depends on router placement, traffic routing and channel assignment. This work seeks to jointly optimize the placement, routing and channel assignment for mesh deployment given flow requirements. The problem is complex because router placement changes network topology which in turns impacts...
We consider joint subchannel and power allocation for an orthogonal frequency division multiple access (OFDMA)-based cognitive radio network. We formulate the downlink resource allocation problem as a spectral-footprint (bandwidth-power product) minimization problem under interference threshold at primary users, total power and quality of service constraints. The cognitive base station solves this...
In heterogeneous networks (HetNets), due to transmit power disparity between macro and pico base stations (BSs), the conventional strongest downlink (DL) reference signal received power (RSRP) based user association results in high uplink (UL) interference. Such interference degrades the UL performance especially in terms of energy efficiency. In this paper, we propose Joint Uplink and Downlink User...
In the presence of co-channel interference in cellular networks, interference mitigation by detecting the desired signal jointly with the interference promises considerable gain over the conventional way of handling the interference as colored Gaussian. Even though such interference-aware detection can improve the performance, it requires some information on the interference. In particular, the modulation...
Due to high system capacity requirement, 3GPP Long Term Evolution (LTE) is likely to adopt frequency reuse factor 1 at the cost of suffering severe inter-cell interference (ICI). One of combating ICI strategies is network cooperation of resource allocation (RA). For LTE uplink RA, requiring all the subcarriers to be allocated adjacently complicates the RA problem greatly. This paper investigates the...
This paper presents an analytical study on the outage performance of cognitive decode-and-forward (DF) two-way relaying networks with underlay spectrum sharing. The bidirectional protocol, i.e., two time-slot multiple access broadcast (MABC) and three time-slot time division broadcast (TDBC), are considered. We propose a definition of outage probability by jointly considering outage events in the...
Coherent joint transmission (CJT) algorithm has been extensively investigated in multi-cell cooperative downlink transmission due to its huge potential performance gains. Comparing with the existing CJT algorithm based on the multi-user eign-mode transmission, an enhanced CJT (eCJT) algorithm is proposed in this paper to further enhance the performance of cellular network in terms of spectral efficiency,...
This paper investigates the potentials of Traffic Steering (TS) in Carrier Aggregation (CA) deployments. TS is defined as the mechanism to optimally distribute traffic among the deployed cells. Obviously, such functionality is rather crucial in scenarios where solely non-CA User Equipments (UE) are present. The introduction of CA is expected to simplify inter-layer load balancing, as CA UEs can concurrently...
In cellular networks, the introduction of device-to-device (D2D) technology could promote cell coverage and improve user experience. In this paper, we consider the scenario of relay assisted D2D communications, and propose a relay selection and resource allocation joint algorithm. The algorithm takes relay selection and resource allocation into consideration simultaneously. And we determine the optimal...
In current wireless cellular networks, interference has become the major obstacle to high spectral efficiency because of universal frequency reuse. Base station cooperation, also referred to as coordinated multi-point processing or transmission(CoMP), has emerged to mitigate it by estimating and avoiding interference from adjacent base stations(BSs). Through analyzing the scenario of CoMP, we formulate...
Since both transmission power and modulation method can be varied in Mobile Ad hoc Networks (MANETs), it is necessary to take power control and rate adaptation into account when dealing with routing problems. In this paper, we propose a Q-Learning-based Rate-aware Power-Controlled Routing scheme (QLRPCR) to address the joint optimization of power, rate and routing in an on-demand and distributed manner...
Increasing the cell edge user throughput in the Long Term Evolution (LTE) systems is a relatively new arising research area. The requirement for higher data rates especially at cell edges is becoming ever more pressing as the advantages could help satisfy better Quality of Service (QoS) on an enduser level and mean higher profitability on the operator side. Therefore developing algorithms and techniques...
This paper investigates joint relay selection (RS) and power allocation (PA) in cognitive radio (CR) systems, in which relay nodes operate in amplify-and-forward (AF) mode. In contrast to the conventional schemes, we take into account the performance of the secondary user (SU) which acts as the relay. A two-step optimization scheme is proposed to maximize system throughput with minimum rate guarantees...
This paper studies distributed interference management for femtocells that share the same frequency band with macrocells. We propose a multi-agent learning technique based on distributed Q-learning, called subcarrier-based distributed resource allocation using Q-learning (SBDRA-Q). SBDRA-Q operates under three different learning paradigms: Independent (IL), Cooperative (CL) and Weighted Cooperative...
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