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With the rapid increase in the use of smartphones and data traffic load on the base stations increasing everyday, an alternative mode of communication is the need of the hour. Device-to-device (D2D) communication allows devices to connect to each other directly without the intervention of the base station. Besides, it provides high spectrum efficiency and a much better signal-to-interference-plus-noise...
Full duplex MIMO communication is one of the key techniques for 5G wireless communication. The main challenge in full duplex operation is the cancellation of the self-interference (SI). In this paper, Transmit Antenna Cancellation technique is considered with symmetric placement of antennas to cancel SI in full duplex MIMO systems. The performance of a full duplex system with this cancellation technique...
Massive MIMO is an energy efficient technique which utilizes frequency spectrum efficiently and provides secure and sturdy system. Therefore it is going to be backbone of future broadband network. Multi-cell Massive MIMO system reused orthogonal pilot sequence which results in pilot contamination. Pilot contamination causes poor channel estimation at the BS and degrades the performance of the system...
CSMA/CA packet relay schemes can improve reliability of ITS V2V communication by compensating propagation loss and fading. However, their performance is affected by hidden terminal (HT) problem, especially when the density of vehicle stations is high. An improved scheme employing sectorized relay station has been proposed to mitigate the problem, and its effectiveness has been shown by some simulations...
During the past decade, Molecular Biology wet labs and sequencing activities have been generating a vast amount of data, causing an increase in the adoption of new methods and tools for identification and analysis. In particular, the use of software agent technology in bioinformatics applications has been on the rise, due some of its unique features as autonomy and remote execution capabilities. However,...
In this paper, multiuser multiple-antenna (MUMIMO) relay networks employing opportunistic scheduling and operating in the presence of rayleigh fading and co-channel interference are analyzed Notwithstanding the system complexity, due to the newly found complementary moment generating function transform (CMGF) operator, an exact expression for the capacity under general conditions is obtained. Moreover,...
In this paper, we develop a framework in which single antenna user equipment (UEs) can be clustered together, thus virtually forming a multi-antenna device. Since the antennas for a virtual device are located on different physical devices, applying previous beamforming methods requires the exchange of the channel state information (CSI) between the UEs within a virtual device which in turn induces...
The performance of a cooperative downlink (DL) time-frequency (TF) spread multi-carrier direct-sequence code-division multiple-access (MC-DS-CDMA) system in the presence of multi-user interference (MUI) and inter-relay interference (IRI) is considered in this paper. Transmitter preprocessing (TP) is employed at the base station (BS) to suppress the MUI at the relay stations (RSs). Similarly, we employ...
This paper addresses the fairness-based pilot allocation (PA) problem in multi-cell time-division duplex (TDD) massive MIMO systems. In such systems, the pilot contamination constitutes a major bottleneck, making the signal-to-interference ratio (SIR) saturated. In this work, we first derive the relation between asymptotic uplink SIR and PA. Based on the derived SIR, a fairness-based PA problem is...
Fifth-generation cellular networks are expected to exhibit at least three primary physical-layer differences relative to fourth-generation ones: millimeter-wave propagation, antenna-array directionality, and densification of base stations. In this paper, the effects of these differences on the performance of single-carrier frequency-domain multiple-access uplink systems with frequency hopping are...
In this paper, we analyze the outage probability of the full-duplex relaying (FDR) system with non-negligible residual self-interference (RSI). By investigating the signal-to-interference-plus-noise ratios (SINRs) at the relay and the destination, the exact expression of the outage probability for selective decode-and-forward (SDF) protocol is derived in closed-form over Nakagami-m fading channels...
In this paper, we consider an uplink massive MIMO systems with dual-antenna users, and investigate the performance of several popular transmission schemes, such as orthogonal space-time block coding (OSTBC), transmit beamforming (TB) and transmit antenna selection (TAS). The achievable sum rate lower bound and asymptotic power scaling performance when M →∞ are presented, where M is the number of base...
This work studies the impact of outdated channel state information (CSI) on decode-and-forward (DF) buffer-aided underlay cognitive relay networks (CRNs), with the following three key constraints considered: the maximum transmit power of the secondary network (P), the peak interference power at the primary user (I) and the interference power at the secondary network caused by the primary network (P...
Coordinated transmission is an effective way to deal with the inter-cell interference (ICI) problem in a multi-cell distributed antenna system (DAS). However, in a practical scenario, the inter-cell channel state information (CSI) is usually imperfect, consequently causing a significant performance degradation of coordinated transmission. In this paper, to tackle this difficulty, we propose a coordinated...
In this paper we consider the problem of pilot contamination reduction in time division duplexing (TDD) cellular networks with large antenna arrays at each base station. Shifting pilot locations in time is an effective way to obtain better channel estimation and therefore reduce inter-cell interference. We study the method further, and propose a low-complexity time-shifted pilot allocation algorithm...
Hybrid cognitive radio (CR) networks can jointly utilize both licensed and unlicensed radio resources to gain better performance over pure licensed/unlicensed networks. This paper studies the system-level capacity of a hybrid cellular network that consists of licensed base stations (BSs) and unlicensed CR relays. Two limiting cases are considered, in which the CR relays are assumed to have infinite...
In this paper the performance of wireless receiver with an automatic frequency control (AFC) loop in the presence of α-μ multipath fading and single interference is considered. Closed form expression for average switching rate (ASR) is obtained and used for evaluation of the mean time to loss of lock (MTTL). Numerical results are presented and used to determine the influence of α-μ fading parameters...
IP networks realized with E-bands radio links with capacity above 1Gbit/s are deployed in 3G and 4G mobile communication systems, Internet provider's networks, as a protection or alternative to optical fiber. E-band radio links are susceptible to rain attenuation, which can cause outages that last usually several minutes, and can cause significant traffic loss. The fact that attenuation between links...
In this paper, we investigate two partial relay selection (PRS) protocols in underlay cognitive radio under impact of hardware impairment. In particular, the re-active and pro-active PRS schemes are proposed to compensate the performance loss due to the hardware noises and the interference constraints required by multiple primary users (PUs). Moreover, incremental relaying technique is also used to...
This paper analyzes outage performance of cognitive cooperative networks with best relay selection (BRS) and maximum ratio combining (MRC) under maximum transmit power constraint, licensed outage constraint, erroneous channel information, independent non-identical (i.n.i) fading channels, and licensed users' interference. To this end, we firstly propose power allocation for unlicensed transmitters...
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