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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...
In this paper, we study the uplink (UL) and downlink (DL) ergodic capacity in the bidirectional dynamic network (BDN). By dynamically allocating the numbers of UL and DL remote radio heads (RRHs), BDN facilitates simultaneous UL and DL communications to accommodate the data traffic asymmetry. Assuming that the number of antennas at each RRH (M) is large, we derive the closed-form expressions for the...
It has become apparent that current fronthaul technology cannot be simply extended to meet the projected demands of 5G and beyond mobile systems. This current technology, based on the transport of sampled radio waveforms, has been the preferred option, with analog radio over fiber reserved to relatively niche application scenarios. However, for future systems, it is recognised that different functional...
A dual band CPW-fed Koch fractal antenna, suitable for WLAN and WiMAX operations, is proposed in this paper. The antenna has been designed by increasing the perimeters of right angled isosceles triangular shape patch by using self-similarity property. The proposed antenna is fed by a 50Ω Microstrip line and fabricated on a low-cost FR4 substrate having dimensions 40 (L) × 40 (W) × 1.59(H) mm3. The...
Today, the wireless communications systems have become an integral part of daily life and continue to evolve in providing better quality and user experience. One of the recent emerging wireless technologies is millimeter wave (mm-wave) technology. It is important to note that mm-wave technology has been known for many decades, but has mainly been deployed for military applications. Over the past 5–6...
Distributed antenna systems (DAS) are one of good solutions to demands of the rapidly increasing data traffic and reduce the system complexity and manage the cellular mobile communication system more efficiently. DAS consist of base band unit (BBU) and remote radio heads (RRHs). BBU and RRHs connected through a fiber optic cable which is still expensive. In this paper, the modular radio units (RUs)...
In mobile communication, frequency is an important resource for wireless communication. As frequency is limited, it is managed by the country and is distributed according to use. As a result, the frequency used for mobile communication is different is each country. In order to make a terminal that is usable in many countries, the terminal must be able to receive several frequency bands. This paper...
Typically, geometrically symmetric 2-port Multiple Input - Multiple Output (MIMO) antennas for LTE-enabled small mobile wireless devices feature radiation modes with significantly different radiation quality factors. It is difficult to precisely match radiation modes over the desired frequency band. Therefore, a solution for low-loss electrical tuning is of interest. The new solution, reported in...
In this paper, a new design of a compact circular shaped microstrip antenna with multifrequency bands is presented. The proposed antenna has a wideband which covers PCS/DCS, UMTS and WLAN bands. Several properties of the proposed compact antenna such as impedance bandwidth, radiation pattern and gain have been numerically and experimentally investigated. Keywords: compact antenna; wideband; wireless...
Recently, a distributed architecture for base stations was proposed. In this new configuration, the base station is separated into two parts: the radio frequency part near the antenna and the baseband processing unit. The interface connection between them is ensured by an optical fiber. In this paper, we present the ongoing works on standardization of the optical interface and the proposed solutions...
This paper presents an efficient technique to enhance the isolation between two closely spaced PIFAs for MIMO mobile terminals. The proposed decoupling method is based on a T-shape slot impedance transformer and it enables an inter-PIFA spacing of 1 mm to be achieved. The 10 dB impedance bandwidth and 20 dB isolation bandwidth cover the 2.4 GHz WLAN band (2.4–2.48 GHz), with a maximum isolation of...
The next generation of aeronautical communications for airport surface applications has been identified through a NASA research program and an international collaborative future communications study. The result, endorsed by both the United States and European regulatory agencies is called AeroMACS (Aeronautical Mobile Airport Communications System) and is based upon the IEEE 802.16e mobile wireless...
In-home networking is becoming a reality. New multimedia applications envisaged for in-home networks require data rates of hundreds of Mbps. In order to provision these applications, wireless networks should provide the user with high speed transmission using short-range Gbps wireless technology. With its unlicensed 5 GHz of spectrum, 60 GHz is envisaged for indoor broadband wireless networks. However,...
In this paper, we report on a mobile broadband wireless access (MBWA) system field trial with Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiplexing (FLASH-OFDM), which was carried out at Sendai city in Japan. This paper describes coverage estimates of an downlink 64 quadrature amplitude modulation (QAM) signal under the condition of constant base-station output power...
This paper presents a comprehensive simulation study on the performance of broadband coupling-element-based multiantenna structures on a mobile terminal at the 2000 MHz Universal Mobile Telecommunications System (UMTS) frequency band with varying two significant hand effects; vertical position of hand along terminal chassis, and distance between hand palm and terminal chassis. The results reveal that...
The design, simulation and analysis of artificial magnetic conductors (AMCs) are presented. In contrast to the current realization of AMCs, such as mushroom and photonic bandgap surfaces, the presented AMCs have a bandwidth percentage more than 25% and work in dual-frequency, which are greatly beneficial to the modern communications and low-profile antennas. The full-wave simulation results verify...
In recent years WiMAX has been presented by its promoters as a complete solution for the broadband access market. Since it is a wireless technology, it can easily serve the most remote and difficult areas. Even more important, the mobile version of WiMAX added the potential of sustainable growth and later adaptation of all its services to compete at the fixed and mobile markets. This paper attempts...
A technique for reducing the antenna induced electromagnetic fields in the vicinity of the earpiece speaker in mobile phones is presented, thereby improving the hearing aid compatibility (HAC). By introducing resonant quarter-wave short-circuited transmission lines to each long side of the chassis edges, the earpiece speaker section of the chassis is electrically decoupled from the antenna section...
Small antenna arrays, e.g. for mobile terminals, suffer from diversity loss due to mutual radiator coupling. We describe the design and characterisation of compact arrays with enhanced diversity performance employing decoupling and matching networks. Essential indications for the radiation properties are obtained from the scattering parameters of the antenna system.
This paper discusses the effects of conductive objects such as the display or the battery of the mobile terminal on the performance of mobile terminal antennas based on direct coupling, i.e. antennas fed across a slot in the mobile terminal chassis without any antenna elements. In addition, a method using inductive loading to partly compensate these effects is demonstrated with an example antenna...
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