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Access reservation based on slotted ALOHA is commonly used in wireless cellular access. In this paper we investigate its enhancement based on the use of physical-layer network coding and signature coding, whose main feature is enabling simultaneous resolution of up to K users contending for access, where K ≥ 1. We optimise the slot access probability such that the expected throughput is maximised...
Video streaming is the most popular application in today's mobile Internet and its growing demands and popularity put more and more load on cellular networks. In a recent trend to mitigate the cellular load, followed by many providers, users are offered to offload mobile connections to WiFi hotspots, which are predominately deployed in urban environments. In this work, we conduct a simulative performance...
To meet the challenge of the ever-growing traffic volume in current wireless communications, ultra-dense network (UDN) deployment with high system capacity has attracted wide attention in recent years. However, existing researches on UDN mainly focus on system throughput while ignore energy efficiency (EE). Therefore, we will analyze the UDN performance including not only system throughput but also...
Cognitive Radio (CR) with the capability of discovering the unused spectrum promises higher spectrum efficiency - a pressing requirement for 5G networks. However, CR owes this capability to power-hungry tasks, most particularly to spectrum sensing. Given that advances in battery capacity has a slower pace compared to advances in device capabilities and traffic growth, it is paramount to develop energy-efficient...
Mobile user equipment relay (UER) has been introduced by 3GPP to enhance communication reliability through device-to-device (D2D) communications. However, as UER needs to use its own power to forward other user's data, D2D communication may be unreasonable to the UER. To overcome this issue, motivated by the recent progress in energy harvesting (EH) techniques, we propose a D2D communication provided...
In this paper, we propose a simplified approach for the Mixed Integer Non-linear Programming (MINLP) problem in the context of dynamic resource allocation for multiuser downlink Orthogonal Frequency Division Multiplexing (OFDM) systems. Our solution is based on the appropriate selection of the K-best branches of the branch and bound technique. The proposed algorithm significantly decreases the computational...
Ultra dense indoor deployment is widely recognized as one of the predominant network configurations of the future wireless systems. Dense indoor deployments are characterized by severe interference between co-channel access points deployed usually in close proximity of one another. Thus the effectiveness and efficiency of interference management techniques is the key to the success of ultra dense...
This paper addresses the problem of rate selection for the cooperative hybrid automatic repeat request with chase combination (HARQ-CC) system, where time correlated Nakagami-m fading channels are considered. To deal with this problem, the closed-form cumulative distribution function (CDF) for the combine SNRs through maximal ratio combining (MRC) is first derived as a generalized Fox's H̄ function...
Traffic demands of mobile radio network have been tremendously increasing in the recent years due to the enormous success of smartphones and their continuous feature evolution requiring higher data rates. Heterogeneous networks (HetNets) consisting of low-power small cells underlying the existing macro cells represent the preferred solution to increase the capacity of cellular systems by means of...
Heterogeneous networks are considered a promising solution to address the explosive increase in wireless networks capacity demand. Due to their limited coverage, small cells offer better area spectral efficiency than macro-cells, and advanced features, such as cell range extension, aim at biasing the choice of users towards small cells. Whereas these features are designed to maximise the air interface...
The pilot reuse issue in massive multi-input multi-output (MIMO) antenna systems with interfering cells is closely examined. This paper considers scenarios where the ratio of the channel coherence time to the number of users in a cell may be sufficiently large. One such practical scenario arises when the number of users per unit coverage area cannot grow freely while user mobility is low, as in indoor...
The use of the unlicensed spectrum by LTE networks (LTE-U or LAA-LTE) is being considered by mobile operators in order to satisfy increasing traffic demands and to make better use of the licensed spectrum. However, coexistence issues arise when LTE-U coverage overlaps with other technologies currently operating in unlicensed bands, in particular WiFi. Since LTE uses a TDMA/OFDMA scheduled approach,...
In this paper, we investigate the optimal spectrum leasing and sharing for dynamic spectrum access (DSA) network which actively shares its spectrum resource with a group of secondary users (SUs) for reaping revenue. The DSA aims at maximizing its total charge to the SUs based on their achieved throughput, while taking into account the additional power consumption of the primary user (PU) to overcome...
This paper addresses the problem of joint routing and backhaul link scheduling in a dense small cell network using 60GHz multi-hop backhaul, coordinated by a local Cloud-RAN central unit. Our objective is to optimally select the backhaul links and paths to be activated in time domain to enhance the cell throughput and to minimize the total delay, considering the backhaul channel conditions and the...
Innovations enabling efficient spectrum utilization is a key element to optimize user experience with growing data demand. This paper discusses the approach of extending enhancements in cellular technology like LTE to unlicensed band for higher spectral efficiency and better user experience. A key challenge for such extension is the coexistence with legacy technology such as Wi-Fi. The description...
A network with densely deployed access points can perform better and more reliably by adapting the transmission parameters like transmission power, minimum size of contention window (cwmin), maximum size of contention window (cwmax) and transmission rate. To understand the impact of these parameters on performance of CSMA-based protocol in a multi-AP network, we are building a testbed called DAPnet...
In wireless LANs, MAC protocols perform one of the most important tasks: efficiently sharing the limited bandwidth among the contending stations. In IEEE 802.11, Distributed Coordination Function (DCF) is used as a default MAC protocol. Despite its wide acceptance, it has two major downsides: i) Channel idle time and ii) Collision overheads. Besides, the use of the explicit ack frames incurs extra...
Software defined networking[1][9] has brought a rapid change in networking industry by providing programma-bility and abstraction. it also enables centralization of control in infrastructure. In this paper, we describe the results of our experiment to determine the performance of SDN by simulating Open vSwitch under conditions of congestion. We did experiments on MININET by creating four compute nodes...
Horizontal spectrum sharing occurs when multiple users share a given band of frequencies with no central control or coordination, and all users compete for access to the available spectrum. Depending on the actual approach used to allocate transmit power over available channels, mutual interference may affect user performance. Three types of horizontal spectrum sharing scenarios will be outlined in...
Cognitive radio networks (CRNs) have become a popular research topic in recent years. Most existing CRN routing schemes focus on building a route that optimizes a single aspect of a network's performance, such as minimizing interference for primary users, or reducing the propagation delay or hop count. They do not consider the overall transmission performance for secondary users. In this work, our...
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