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This paper studies the bidirectional user scheduling and mode selection in single-cell full-duplex (FD) system, where a FD base station (BS) serves multiple uplink and downlink half-duplex (HD) users. Due to the existence of the inter-user interference from an uplink transmitting user to a downlink receiving user, the system operating in FD mode does not necessarily outperform HD mode, depending on...
Weighted queue minimization is considered in Dynamic TDD system where the available resources per cell and per TDD frame can be freely allocated to both uplink (UL) and downlink (DL) transmission depending on traffic demand and user distribution within the network. Given the traffic state, joint UL/DL cell mode selection, beamformer design and resource allocation among available time/frequency/space...
In this paper, we analyze the downlink (DL) performance of superimposed pilots in time division duplexing massive multiple-input multiple-output (MIMO) systems, and show that superimposed pilots offer an increased resilience to pilot contamination with respect to time-multiplexed pilots and data. Based on a closed form expression for the DL signal-to-interference-plus-noise ratio (SINR) at the user...
To facilitate content delivery to mobile users, we propose a content caching and distribution framework for the heterogeneous OFDM networks, where a library of files available at the macro base station (MBS) can be distributively cached in multiple serving nodes (SNs). SNs are capable of both receiving unstored files from MBS and transmitting files to the associated users. For a given group of file...
To achieve a significant boost on capacity performance in the next generation (5G) cellular network, novel radio access technologies (RAT) are demanded to make the system more spectrum efficient. As a promising multiple access scheme for 5G cellular network, non-orthogonal multiple access (NOMA) has attracted extensive research attention recently. Existing works show that NOMA posses the potential...
This paper investigates the performance of bidirectional dynamic networks (BDN) with massive multiple input multiple output (MIMO) systems. In BDN, dynamic allocation of the number of uplink and downlink remote radio heads (RRHs) is proposed, which offers a flexible solution to balance the data traffic asymmetry without requiring the time synchronization. Intuitively, the interference between the...
In this paper, we consider a heterogeneous network composed of a full-duplex macrocell and a half- duplex femtocell. The macro-base station (BS) is equipped with L antennas where each antenna can be utilized either for downlink transmission or uplink reception. On the other hand, the femto-BS is equipped with M antennas that are used for downlink transmission. We assume that each user equipment has...
Deployment of femtocells have emerged as a promising technique to address the need for the exponentially increasing mobile traffic demand. They can also improve the capacity and coverage for the indoor wireless users. However, the cross-tier interference in such heterogeneous networks between the femtocells and the macrocells is a design challenge which should be answered before such deployment. In...
In this paper, we provide an analytical framework to analyze heterogeneous downlink mmWave cellular networks consisting of tiers of randomly located base stations (BSs) where each tier operates in a mmWave frequency band. Signal-to-interference-plus-noise ratio (SINR) coverage probability is derived for the entire network using tools from stochastic geometry. The distinguishing features of mmWave...
Rateless codes have been shown to provide robust error correction over wireless channels. Using a stochastic geometry model, this paper studies the performance of cellular downlink with packet transmission based on rateless codes. For the case of Rayleigh fading, a novel and accurate approximation is proposed for the distribution of the packet transmission time of rateless codes. The performance of...
In this paper, the application of non-orthogonal multiple access (NOMA) into $K$-tier heterogeneous networks (HetNets) is investigated. A new promising transmission framework is proposed, in which massive multiple-input multiple-output (MIMO) is employed in macro cells and NOMA is adopted in small cells. For maximizing the biased average received power at mobile users, a massive MIMO and NOMA based...
Full-duplex (FD) small cells provide a promising solution for meeting the sought requirements of future wireless networks, specifically, the capacity, coverage and spectral efficiency. Motivated by the recent developments in self-interference (SI) cancellation techniques, the main objective of this paper is to further investigate the impact of using fully FD- capable small cells on conventional HetNets...
In this paper, we study the power allocation problem for the downlink transmission in a set of closed-access femtocells which underlay a number of macrocells. We introduce a mutli-step pricing mechanism for the macrocells to control the cross- tier interference by femtocell transmissions without explicit coordination. We model the cross- tier joint power allocation process in the heterogeneous network...
This paper proposes a novel polarization-based underlay spectrum sharing scheme in cognitive heterogeneous cellular network (CHCN). Distinguished from traditional spectrum sharing exploiting spectrum opportunities in time, frequency, space and power domains, we exploit spectrum opportunities in polarization domain to enable small cell to coexist with macrocell. The proposed scheme optimizes the transmitting...
Small cell networks are considered one of the key technologies in the next generation wireless networks. One of the main challenges in this area of research is how to tackle the problems of interference and resource allocation, especially for the hyper dense deployment of small cells. In this paper, we study the problem of cooperative interference mitigation in a small cell network. In particular,...
Power ramping is one of the mechanisms proposed to help alleviate congestion during random access in LTE cells. We evaluate its performance taking into account preamble SINR considerations as well as Physical Downlink Control Channel (PDCCH) deficiency. Our results show that power ramping can speed up access at small to moderate loads, but that it is actually detrimental at moderate to high loads,...
This article investigates the performance of an ultra-dense network (UDN) from an energy-efficiency (EE) standpoint leveraging the interplay between stochastic geometry (SG) and mean-field game (MFG) theory. In this setting, base stations (BSs) (resp. users) are uniformly distributed over a two-dimensional plane as two independent homogeneous Poisson point processes (PPPs), where users associate to...
Due to the unique spatial and temporal focusing effects, time-reversal (TR) communication can be utilized in the cloud radio access network, where it creates a tunneling effect such that the traffic load in the front-haul links can be alleviated in both downlink and uplink. Although the basic TR waveforms are simple to use, they cannot provide the optimal performance in some cases. While the cloud...
Abstract-Conventional cloud radio access networks assume single cloud processing and treat inter-cloud interference as background noise. This paper considers the downlink of a multi-cloud radio access network (CRAN) where each cloud is connected to several base-stations (BS) through limited-capacity wireline backhaul links. The set of BSs connected to each cloud, called cluster, serves a set of pre-known...
This paper studies privacy-preserving for downlink transmission in multiuser relay systems, where a source communicates with multiple users via a relay employing the amplify-and-forward (AF) protocol. At any scheduling unit, only one user (desired user) is selected to receive the source information, and the other users (undesired users) are viewed as potential eavesdroppers due to the broadcast nature...
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