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In this paper, we study a multi-level power allocation scheme for SUs in cognitive radio systems that uses a new frame structure to improve overall throughput of the system. The scheme is different from the conventional strategies in that the PU can now transmit with multiple levels of power rather than a constant level of power, which seems to be more realistic and practical. Our proposed strategy...
Unmanned aircraft systems are expected to open pathways towards the development of many new services. Owing to their airborne flexible mobility, systems using unmanned aircraft (UA) have a significant potential to change our daily lives. However, several issues with such systems need to be addressed. In particular, wireless transmission of data such as high quality video from a UA to Ground Stations...
Device-to-device communication and energy harvesting are both key technologies to improve spectrum and energy efficiency. In this paper, we investigate the resource allocation problem for the energy harvesting-powered D2D communication underlaying cellular networks, where D2D pairs firstly harvest energy and then transmit information signals. The goal is to maximize the sum throughput via joint time...
Millimeter-wave (mm-wave) communication is a promising technology for supporting extremely high data rates in the next generation wireless networks. Mm-wave signals experience high path loss and directional transmission is required to compensate the severe channel attenuation. The special characteristics of the mm-wave propagation arise opportunities as well as challenges for the network resource...
Mobile services, especially video streaming, has seen a rapid usage increase in recent years. Base stations (BSs) need to employ smarter and efficient resource allocation strategies to maintain high quality of service (QoS) to users at all the times. Predictive resource allocation (PRA), is one such novel scheme, in which BSs seek to anticipate the user demands and offer service to users in advance...
In this paper, we investigate optimal resource allocation for multicarrier (MC) multiple-input single-output non-orthogonal multiple access (MISO-NOMA) downlink systems. The resource allocation design for the maximization of the weighted system throughput is formulated as a non-convex optimization problem taking into account the quality-of-service requirements of the downlink receivers. We employ...
In this paper, we investigate the energy efficiency (EE) and spectral efficiency (SE) tradeoff in multi-cell heterogeneous networks (HetNets). Our objective is to maximize both EE and SE of the network while satisfying the rate requirement of users. We use multi-objective optimization techniques to define the objective function. We propose a three-stage algorithm in this paper. First, we select the...
This paper focuses on resource allocation in heterogeneous Ultra Dense small-cell Networks (UDNs), in which massive overlaid small cells are under the coverage of a macro cell. In UDN, both co-tier and cross-tier interference need to be taken into account. When increasing the deployment density of Small-cell Base Stations (SBSs) and the unreasonable energy usage, it results in serious interference...
In this paper, we investigate the delay and delay-constrained throughput performance of a point-to-point wireless-powered communication system, where one node, e.g. a user equipment (UE), is powered by the wireless energy transferred from the other node, e.g. an access point (AP), and uses the harvested wireless energy to send data to the other node. Our focus is on the delay performance of sending...
Hybrid beamforming (BF) is a widely considered strategy to enable downlink multiuser transmission for mmWave communication systems. However, current mmWave WiFi standard, the IEEE 802.11 ad, does not support hybrid BF because it could only serve one user at a time. Thus, it is important to implement hybrid BF based on IEEE 802.11.ad such that it could be applied in future mmWave WiFi. In this paper,...
In this paper, we investigate the energy-efficient resource allocation problem in the downlink of an Orthogonal Frequency Division Multiple Access (OFDMA) system with multiple users. A iterative algorithm is developed to maximize the overall energy efficiency of the downlink transmission by allocating the resource blocks (RBs) and the transmit power, which is constant for all RBs assigned to a given...
Ambient energy harvesting has emerged as a promising technique to improve the energy efficiency and reduce the total greenhouse gas emissions for green relay networks. In this paper, we study the joint relay selection and power control problem for the Decode-and-Forward energy-harvesting wireless relay network. In particular, the problem formulation is to maximize the end-to-end system throughput...
In Long Term Evolution-Advanced (LTE-A) networks, different aspects of radio resource scheduling such as fairness and Quality of Service (QoS) assurance must be provided for heterogeneous traffic, having different characteristics. However, the ever-growing number of mobile devices sharing the limited radio resources leads to the high cost and difficulty for information acquisition and computations...
Orthogonal frequency division multiple access (OFDMA) is considered as a promising technique to overcome interference in multi-cell cellular networks. However, the mobility of heterogeneous user equipment brings new challenge to traditional OFDMA network. The current research about OFDMA system mostly based on multi-cell cellular system that is not perfectly compatible with the future networks, for...
Interference, which can be caused by Secondary Users (SUs) to other Primary Users (PUs) or SUs, is of major concern for Cognitive Radio Networks (CRNs). We study a spectrum allocation problem, where our primary focus is on maximizing the throughput of the CRN while protecting the PUs from interference and controlling the co-channel interference among the SUs. We build a CRN, where initially, all SUs...
Distributing scarce spectral resources among the unlicensed users has been an attractive research area for Cognitive Radio Network's (CRN) research community. A resource distribution technique, which emphasizes fairness, ensures allocation of resources for all Secondary Users (SUs) irrespective of their data rates and may cause efficiency loss for the CRN. On the other hand, a throughput based resource...
Wireless backhauling is a promising technology for Ultra-Dense Networks (UDN). Resource management for access and backhaul is a key issue. Different from conventional resource allocation approaches, we partition radio resources for access and backhaul, taking into account the impacts of cooperative transmission modes. This problem is formulated to maximize the area throughput of UDN to obtain the...
We analyze the performance of the type-I automatic repeat request (ARQ) protocol with ultra-reliability constraints. First, we show that achieving a very low packet outage probability by using an open loop setup is a difficult task. Thus, we introduce the ARQ protocol as a solution for achieving the required low outage probabilities for ultra reliable communication. For this protocol, we present an...
Hybrid ARQ (HARQ) and link adaptation (LA) are two powerful techniques to improve the data throughput in wireless communication systems. However, when integrated with LA, conventional HARQ does not provide much gain over LA without significantly increasing the number of retransmissions and initial coding rate. In this paper, we explore the feasibility of achieving high throughput by combining HARQ...
Devlce-to-devlce (D2D) communications are capable of enhancing the total cell throughput, reducing power consumption and increasing the instantaneous data rate. In this paper we propose a distributed power allocation scheme for D2D communications overlaying an OFDMA network, so that D2D communications take place on dedicated resources but are supervised by the BS. The proposed scheme addresses the...
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