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In this paper, the application of non-orthogonal multiple access (NOMA) to millimeter-wave (mmWave) communications is considered, where random beamforming is used in order to reduce the system overhead. Stochastic geometry is used to characterize the performance of the proposed mmWave-NOMA transmission scheme, by using the key features of mmWave systems, e.g., mmWave transmission is highly directional...
This work encompasses Rate-Splitting (RS), providing significant benefits in multi-user settings in the context of huge degrees of freedom promised by massive Multiple-Input Multiple-Output (MIMO). However, the requirement of massive MIMO for cost-efficient implementation makes them more prone to hardware imperfections such as phase noise (PN). As a result, we focus on a realistic broadcast channel...
Conventional microwave bands are expected to encounter bandwidth shortage due to the ever-increasing demand for high speed wireless services. The use of millimeter wave (MMW) spectrum has been regarded as one of the promising solutions to support data traffic demands in future cellular networks. MMW cellular networks are envisioned to be densely deployed to attain acceptable coverage and rate. In...
Centralized Radio Access Network (C-RAN) architecture is considered the only viable solution to handle the complex interference scenarios generated by massive antenna and small cell deployment foreseen for next generation (5G) mobile networks. The fronthaul links used to exchange the signal between Base Band Units (BBUs) and Remote Radio Heads (RRHs) are conventionally based on optical fiber, due...
In this paper, the security in a device-to-device (D2D) spectrum sharing network is investigated. The cellular users and eavesdroppers are distributed according to two independent Poisson Point Processes (PPPs), and the positions of the D2D transmitters follow a hard-core point process. Based on the stochastic geometry, we first derive closed-form expressions of the connection and secrecy outage probabilities...
Terahertz band communication is envisioned as a key technology to satisfy the increasing demand for ultra-highspeed wireless links. In this paper, a memory-assisted medium access control (MAC) protocol with angular-division-multiplexing (ADM) is proposed for the service discovery and communications in the THz network. In particular, the efficiency balance is achieved by equipping the nodes with (i)...
We consider a multi-carrier joint processing (JP) coordinated multi-point (CoMP) cellular system wherein the beamformers are designed by a centralized controller (CC). Those are subsequently fed back to the respective base stations (BSs) via finite capacity backhaul link. Hence, we design transmit beamformers at the CC that associate users to BSs depending on their backhaul capacity and users channel...
In this paper, a multi-group multi-way relaying network is considered. Multiple half-duplex nodes form a group and each node wants to share its message with all other nodes in its group via an intermediate half-duplex relay. The nodes of the whole network are equally distributed over the groups. In this paper, we propose a multicast interference alignment algorithm for a multi-group multi-way relay...
Prior results on performance analysis for cognitive relay networks mainly involve perfect channel state information (CSI), which is not readily available. Thus, the effects of outdated CSI on the performance of a multi-antenna multi-relay cognitive radio system are investigated in this work. To exploit the benefits of multiple antennas, collaborative zero-forcing beamforming at the secondary source...
We perform an asymptotic study on the performance of filter bank multicarrier (FBMC) in the context of massive multi-input multi-output (MIMO). We show that the signal-to-interference-plus-noise ratio (SINR) cannot grow unboundedly by increasing the number of base station (BS) antennas, and is upper bounded by a certain deterministic value. This is a result of the correlation between the multi-antenna...
High throughput satellites have proven to be an excellent solution to provide Internet services to white spots or to complement other existing infrastructures. With the use of multi-beam antennas, the same frequency may be reused dozens of times across a single satellite coverage area, increasing the system capacity and profitability. Legacy frequency reuse patterns such as uncoordinated 4-color scheme...
This paper studies the impact of in-phase and quadrature imbalance (IQI) on the downlink of a single-cell multiuser multiple-input multiple-output (MU-MIMO) system with large antenna arrays. Moreover, we consider a time-division duplex (TDD) system where we assume uplink/downlink channel reciprocity in the downlink precoding design. We study the impact of uplink/downlink channel mismatch on the downlink...
We consider an interference network tapped by external eavesdropper(s) in which each legitimate transmit-receive pair conceals its communications by using joint transmit-based friendly jamming (TxFJ) and receiver-based friendly jamming (RxFJ). Specifically, TxFJ is realized at the transmit side using MIMO precoding while RxFJ is achieved at the receiver side of each link by leveraging the state-of-the-art...
Cellular networks operating at millimeter wave (mmWave) frequencies are able to achieve multi-gigabit-per-second data rates due to the large bandwidth available. However, the data transmission range will be shorter and significant signal power difference will be observed between line-of-sight (LOS) and non-line-of-sight (NLOS) links. This paper considers interference management and useful signal enhancement...
In this paper, we study a joint beam and user scheduling problem in a cooperative cellular network utilizing orthogonal random beamforming technique. This paper aims to minimize total base stations' average energy expenditure while ensuring finite service time for all traffic arrivals in a given set. We leverage Lyapunov optimization technique to transform original long-term problem into short-term...
In this paper, we provide a unified framework for the study of multi-cell multi-user large-scale antenna system (LSAS) in both full-duplex (FD) and half-duplex (HD) modes of communications. Here, we employ the Poisson point process (PPP)-based abstraction model of massive-antenna base stations (BSs) and mobile terminals (MTs). The loop-back interference (LI) channels in FD mode are modeled using the...
The concept of Ultra Dense Networks (UDNs) is often seen as a key enabler of the next generation mobile networks. However, existing analysis of UDNs, including Stochastic Geometry, has not been able to fully determine the potential gains and limits of densification. In this paper we study performance of UDNs in downlink and provide new insights on the impact of antenna height on the network performance...
In this paper, flexible frequency division duplex (FDD) and time division duplex (TDD) schemes are considered in FDD spectrum. With FDD spectrum, there is a paired uplink (UL) carrier with each downlink (DL) carrier, each carrier with the same bandwidth. Because equal resources are provisioned for the DL and UL, FDD spectrum is not well suited for asymmetric DL/UL traffic. While the FDD UL-paired...
Time-shifted pilot scheme can efficiency combat pilot contamination. However, when the number of base station (BS) antennas is finite, the pilot interference due to the downlink transmission symbols cannot be mitigated in the time-shifted scheme. This paper proposed a novel two-stage channel estimation algorithm based on time-shifted pilot to reduce the effect of pilot interference. In the first stage,...
In this article, we investigate how the performance of Massive MIMO cellular systems can be enhanced by introducing D2D communication. We consider a scenario where the base station (BS) is equipped with large, but finite number of antennas and the total number of UEs is kept fixed. The key design question is that what fraction of users should be offloaded to D2D mode in order to maximize the aggregate...
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