The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Nowadays, various types of access-points (APs) and hosts such as dedicated APs, laptop personal computers, and mobile terminals have been used in IEEE802.11 wireless local-area networks (WLANs). As a result, the optimal assignment of holding APs into the network field depending on the host type distribution has become very important to improve the network performance. In this paper, we formulate this...
We considered a multi-user MIMO broadcast (BC) system with multiple antennas at both transmitter and receiver sides. A scheduling scheme using semi-orthogonal user selection (SUS) with zero-forcing beamforming (ZFBF) is implemented. The total feedback load required in ZFBF systems is reduced by implementing a two stage feedback scheme by restricting the number of users to participate in each stage...
We are leaving in the world where rapid changes in technologies are taking place. The world is not the same what it was before 20 years. With new technologies every new day, mankind have achieved tremendous amount of dreams which were almost impossible few decades back. Automatic cars, auto navigating planes, goods delivering drones and many more are the dreams going to complete in near future. Navigation...
With the categories of mobile communication services increasing, the positioning technology based on the base station (BS) in long term evolution (LTE) attracts more and more attention. When it comes to realize the indoor positioning of mobile phone, it is relatively difficult due to multipath, pedestrian interference, power attenuation and so on. In this paper, we use the sounding reference signal...
Massive-Multi Input and Multi Output (MIMO) antenna system is considered as the key technology to improve both spectral efficiency (SE) and energy efficiency (EE) for 5G systems. Where pilot contamination and inter-cell interference have been considered as basic limiting factors to achieve high data rate. These parameters will saturate the SE and truncate to a constant value. In this work, we explore...
We consider the problem of designing hybrid analog-digital beamformers in a downlink multi-user large-scale MIMO system. The objective is to minimize the total transmit power, while fulfilling SINR targets of all users. A dual virtual uplink problem is formulated for the original downlink problem based on the uplink-downlink duality theory, in order to decouple the digital beamformers in the constraints...
This work considers the downlink of a multicell massive MIMO system in which L base stations (BSs) of N antennas each communicate with K single-antenna user equipments randomly positioned in the coverage area. Within this setting, we are interested in evaluating the sum rate of the system when MRT and RZF are employed under the assumption that each intracell link forms a MIMO Rician uncorrelated fading...
Degrees of freedom (DoF) is studied in the downlink of a heterogenous wireless network modeled as a two-layered interference network. The first layer of the interference network is the backhaul layer between macro base stations (MBs) and small cell base stations (SBs), which is modeled as a Wyner type linear network. The second layer is the transmission layer between SBs and mobile terminals (MTs),...
We address secure communication for energy-harvesting (EH) based cooperative cognitive radio networks (CRNs), in which several EH secondary users (SUs) cooperate with one primary user (PU) for both data transmission and energy harvesting. To increase the amount of energy harvested by SUs while improving spectrum utilization, we suppose that SUs are equipped with orthogonally dual-polarized antennas...
Ray-based and hybrid propagation models are today considered as valuable solutions to fulfill 5G wireless channel modeling requirements. They are a complement or alternative to the stochastic approaches when link-level and system-level simulations deal with millimeter-wave (mmWave), ultra-dense deployment and/or large antenna arrays. The present article proposes an extension of an urban ray-based...
This work presents an energy efficiency (EE) investigation of a beam generated by the combination of Recursive Least Square (RLS) algorithm and Kaiser side lobe cancellation technique in smart antenna system. The RLS-Kaiser combination is investigated using energy model which is a function of beam width, range and signal to noise plus interference ratio (SNIR). The investigation carried out on linear...
This paper describes the design and simulated performance of a 5G-like spectrum sharing radio that uses both Non-Contiguous-Orthogonal Frequency Domain Modulated (NC-OFDM) waveform and an electrically Reconfigurable Alford Loop Antenna (RALA) to efficiently share spectrum with a co-channel IEEE 802.15.4, or ZigBee, radio link. We present a detailed performance analysis of Monte Carlo simulation trials...
Energy-efïîdent planning is a current challenge for heterogeneous 4g wireless networks, since ‘greener’ strategies typically act against the always growing traffic requirements. However, network-wide optimization of base station antenna patterns can be exploited to that end, leading the total transmit power of the network to a global minimum. This article formulates the coverage and capacity optimization...
Null steering methods usually involve costly and complicated amplitude and/or phase control systems. A new technique is presented for null steering based on the element positions perturbations. This method possesses an even symmetry pattern cancellation, which allows nulls to be imposed at symmetrical positions around the main beam. Also it frees the phase shifters to be used solely for steering the...
Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is known as a high capacity system for data transmission over broadband wireless communication channels. However, the time-varying fading and Doppler effect of the underwater acoustic channel can destroy the orthogonality of subcarriers, causing intercarrier interference (ICI). In this paper, we proposed a combined...
In Cognitive Radio Networks (CRNs), the spectrum underlay approach enables primary and secondary networks to transmit simultaneously, as long as the interference from the secondary network to the primary network is below certain threshold. As the recent advancement of the underlay approach, the transparent coexistence exploiting MIMO interference cancellation was proposed. Previous works assume that...
The hopeful technique Massive MIMO is provided to increase the data rates of mobile communication, by arranging antennas to hundreds of the base stations which is the most promising solution for the fifth generation of cellular communication network. In order to cope with the huge demands of communications in the network it has been found that it is useful to have multiple receivers served in the...
Massive MIMO promises large spectral and power efficiency. However, pilot contamination, a well known challenge in massive MIMO, limits these aspired gains. In this paper, we propose a pilot hopping sequence along with a pilot reuse strategy for pilot decontamination. A simple hopping scheme is proposed and simulated in an uplink L-cells system where every user is assigned distinct pilot sequences...
The paper studies two resource allocation strategies (GRID, anti-EMI) for multi-user OFDMA systems. These strategies are evaluated after being compared with the Round Robin and the FFR strategy in terms of mean throughput and mean dissipated power. All investigated strategies assign resources without Channel State Information (CSI), while both GRID and anti-EMI inherently combat Co-Channel Interference...
In this paper, we consider the achievable secure degrees-of-freedom (sdof) for the multiple-input single-output (MISO) wiretap channel with an unknown Eavesdropper's channel state information (CSI). The underlying system model comprises three nodes: a multi-antenna transmitter (Alice), a single-antenna receiver (Bob) and a single-antenna eavesdropper (Eve). Recent studies have shown that the achievable...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.