Multi-antenna Systems Research Articles

A Novel Geometrical Mixed-Bounce Two-Ring Deterministic Model for MIMO Mobile-to-Mobile Non-Isotropic Communication Channel

An accurate modeling of multiple-input multiple-output (MIMO) channels is a prerequisite for designing multiantenna system. In this paper, we propose a geometrical mixed-bounce two-ring deterministic model for mobile-tomobile channel considering the non-isotropic scattering while adopting the Von Mises probability density function for both the angle of departure AoD and angle of arrival AoA surrounding the transmitter and receiver respectively. Beginning with isotropic scattering, the expression for two dimensional (2-D) space time cross-correlation (STCC) function between any two sub channels is derived. Comparison between the statistical properties of the deterministic model under the assumption of non-isotropic scattering with that of the reference model indicates a good agreement, thus, the importance of this model. The result obtained is in conformity with that of the double bounce and single bounce two ring models.

Resource Allocation with Limited Feedback and Joint Coding Scheme for Wireless Multi-antenna Multicast System

In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, we introduce a resource allocation algorithm by exploiting layered coding combined with erasure correction coding for multicast services in the downlink of OFDMA-based multi-antenna system. To reduce the feedback overhead of uplink, we design a novel transmission scheme with limited feedback. Then, we formulate the joint subcarrier and power allocation problem for the data of base layer and enhancement layers, which is shown to be NP hard. Hence, in order to reduce the computational complexity, we propose a three-phase suboptimal algorithm. The algorithm is designed to maximize the system throughput while at the same time guarantee the quality of services (QoS) requirements of all multicast groups. It is composed of precoding scheme, proportional fairness subcarrier allocation algorithm and modified water-filling power allocation algorithm with QoS guarantees (MWF-Q). To further decrease the complexity of MWF-Q, a power allocation algorithm with increased fixed power allocation algorithm with QoS guarantees is introduced. Simulation results show that the proposed algorithms based on limited feedback scheme significantly outperform CMS and any other existing algorithm with full feedback. Moreover, the proposed scheme can efficiently reduce 50 % of the full feedback overhead.

다중 안테나 기반 위상 차이를 이용한 AOA 측위 기법

In this paper, we have studied the performance of the AOA (Angle of Arrival) in multi-antenna systems for LBS (Location Based Services) and we also analyzed the performance of the AOA in SISO (Single Input Single Output) in multipath environments and their differences. The adequacy of AOA positioning in new communication environments was determined. Currently used positioning methods in 3G communication environment has been developed based on SISO. However, the accuracy of SISO-based TOA (Time of Arrival), TDOA (Time Difference of Arrival), AOA positioning techniques degraded in multipath environments. The communication system will be changed and developed. According to enhanced positioning techniques are required. Using antenna characteristics and the phase difference between antennas of LTE-Advanced standard's key technique MIMO system AOA positioning, and SISO based AOA positioning performance were analyzed. We found that AOA technique potential for use based on Multiple antenna systems by computer simulations.

A smart collision recovery receiver for RFIDs

In this work, we focus on framed slotted Aloha (FSA) and passive ultra high-frequency radio frequency identification multi-antenna systems with physical layer collision recovery. We modify the tags slightly by adding a so-called ‘postpreamble’ that facilitates channel estimation. Furthermore, we investigate the throughput performance of advanced receiver structures in collision scenarios. More specifically, we analyse the throughput of FSA systems with up to four receive antennas that can recover from a collision of up to eight tags on the physical layer and acknowledge all tags involved in that collision. Due to the higher collision recovery capabilities, the frame sizes can be significantly reduced, and thus, the throughput can be increased. We also derive analytically optimal frame sizes, given that a certain number of collisions can be resolved. We further study the constraints to the throughput due to the structure of our receiver and channel estimation for different collision scenarios. Furthermore, we propose a novel collision recovery method with two phases: first, a successive interference cancellation and, second, a projection of the constellation into the orthogonal subspace of the interference. Additionally, the inventory time, i.e. the number of slots necessary to successfully decode all tags in the reader range, is calculated and compared for different receiver types. A validation of our theoretical predictions is achieved by means of simulations. We show that by our proposed methods, we can realistically achieve more than ten times higher throughput or, equivalently, a reduction of the inventory time by more than 90%.

Miniaturization and isolation improvement of a multiple‐patch antenna system using electromagnetic bandgap structures

AbstractIn this article, a compact multielement antenna system composing of microstrip patch antennas is designed by using electromagnetic bandgap (EBG) structures. Two distinct EBG structures are designed to achieve the two objectives of miniaturization and suppression of interelement coupling due to surface waves in a multiantenna system. By embedding an EBG array operating in the slow‐wave region, the area of the microstrip patch antenna is reduced by 67.48%. To alleviate the resulting increased back radiation, a second EBG structure is designed to surround the miniaturized patch antenna and close to 8 dB improvement in the front‐to‐back lobe ratio is achieved. As well, the second EBG design is included in a 2 × 2 multiantenna system to suppress interelement coupling. It is found that the coupling is reduced significantly when utilizing the proposed EBG rings. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1609–1612, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27621

Alternative Algorithm for Determining the Attitude Parameters of a Moving Platform Using Multi-Antenna GNSS Sensors

This case study aims to demonstrate a multi-antenna Global Navigation Satellite System (GNSS) technique and quality evaluation approach that can be used to determine the attitude parameters for a moving platform. First, considering the highly dynamic behavior of a moving platform, a noniterative parameter determination approach was introduced. A rigorous error analysis approach was then established to give explicit indications on the obtained attitude parameters. Based on the numerical results from both simulated and real datasets, it has been illustrated that the proposed approach is capable of giving efficient and reliable attitude parameter estimates independently without the need for auxiliary information. Consequently, the multi-antenna GNSS system can serve as an immediate resolution for the attitude determination of moving platforms in modern day applications.

A 15–40 GHz CMOS True-Time Delay Circuit for UWB Multi-Antenna Systems

A CMOS true-time delay (TTD) circuit operating from 15 to 40 GHz is presented for integrated UWB multi-antenna systems. The TTD circuit employs a distributed active switching structure in which eight cascode switches are distributed along transmission lines, leading to 3-bit variations of the group delay. The size of the switches and the characteristic impedance of the transmission lines are carefully scaled so as to minimize loss variation among the different delay states, while maintaining flat delay performance over a wide bandwidth. The circuit is implemented in a bulk 0.13-μm CMOS technology and exhibits a total variable group delay of 40 ps with an average resolution of 5 ps from 15 to 40 GHz. The insertion loss was 14 dB with a maximum RMS variation of 1.6 dB, while the input and output return loss was better than 10 dB over the operating bandwidth.

Dynamic resource allocation with precoding and joint coding scheme for limited feedback‐based wireless multi‐antenna multicast system

In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, the authors introduce a resource allocation algorithm by exploiting layered coding combined with erasure correction coding for multicast services in the downlink of orthogonal frequency-division multiple access-based multi-antenna system. To reduce the feedback overhead of uplink, the authors design a novel transmission scheme with limited feedback. Then, the joint subcarrier and power allocation problem for the data of base layer and enhancement layers are formulated, which is shown to be non-deterministic polynomial- hard. Hence, in order to reduce the computational complexity, they propose a three-phase suboptimal algorithm. The algorithm is designed to maximise the system throughput, whereas at the same time guarantee the quality of services (QoS) requirements of all multicast groups. It is composed of precoding scheme, proportional fairness subcarrier allocation algorithm and modified water-filling power allocation algorithm with QoS guarantees (MWF-Q). To further decrease the complexity of MWF-Q, a power allocation algorithm with increased fixed power allocation algorithm with QoS guarantees is introduced. Simulation results show that the proposed algorithms based on limited feedback scheme significantly outperform CMS and any other existing algorithm with full feedback. Moreover, the proposed scheme can efficiently reduce 50% of the full feedback overhead.

How do we design CoMP to achieve its promised potential?

Coordinated multipoint, or CoMP, transmission has been recognized as a spectrally efficient technique for full frequency reuse cellular systems, in which base stations cooperate to reduce or eliminate intercell interference. However, there are still many obstacles before it can be put into practical use. In this article, we first discuss the features of CoMP systems and channels that are distinct from single-cell multi-antenna systems. We then give an overview of state-of-the-art approaches for coping with the factors that limit the potential of CoMP. A major issue is the acquisition of channel state information, which creates different challenges for TDD and FDD systems. Another set of challenges arises from the limited capacity available on the backhaul connections between the cooperating base stations. Both the fundamentals of possible solutions and their relations to cellular standards are discussed.

Design and Implement of Multi-Antennas for High Data Rate Communication

In this paper, it tries from experimental measurements to derive the required minimum antenna isolation and from using this minimum antenna isolation to have the MIMO to execute at its utmost efficiency. The issue of the minimum antenna isolation is actually the problem of pursuing the possible antenna module area of a multi-antenna system. As smaller size communication system is explored in real life the request of small size communication system has been discussed and many systems have been developed. To verify the feasibility of designing a multi-antenna and high throughput system is through the adopt of many MIMO technique implemented IEEE 802.11n 2x2 products to verify whether its throughput can be doubled. In this paper we integrate 4 2x2 AP antenna sets and under the operation of 8 antennas to attain the 1200 Mbps PHY rate through proper selection and design of available antennas, for 1200 Mbps PHY rate it is equivalently to have more then 600 Mbps throughput and with this implementation it is enable to prove the feasibility of the designed system.

Performance Analysis of DSTBC over VHF Air-to-Ground Communication Channels

This paper is concerned with evaluating the performance of differential space time block coding (DSTBC) over very high frequency (VHF) aeronautical communication channels (i.e. air-to-ground). Differential phase shift key (DPSK) is one of the differential transmission schemes that transmit information without full channel state information (CSI) at the receiver. There are two main problems that degrade the performance of the communication over this channel, multipath fading which is a common problem in any wireless channel and Doppler shifts which result from aircraft speeds. In order to combat such fading and improve the bit error rate (BER) performance of the communication system over this channel, the paper investigated the usage of multiple input multiple output (MIMO) systems with differential transmission scheme. This was done through computer simulations that analyze the performance of DSTBC using two antennas at the transmitter and N antennas at the receiver. General Terms Wireless communication, multi antenna system.

Near Field UHF RFID Antenna System Enabling the Tracking of Small Laboratory Animals

Radio frequency identification (RFID) technology is more and more adopted in a wide range of applicative scenarios. In many cases, such as the tracking of small-size living animals for behaviour analysis purposes, the straightforward use of commercial solutions does not ensure adequate performance. Consequently, both RFID hardware and the control software should be tailored for the particular application. In this work, a novel RFID-based approach enabling an effective localization and tracking of small-sized laboratory animals is proposed. It is mainly based on a UHF Near Field RFID multiantenna system, to be placed under the animals’ cage, and able to rigorously identify the NF RFID tags implanted in laboratory animals (e.g., mice). Once the requirements of the reader antenna have been individuated, the antenna system has been designed and realized. Moreover, an algorithm based on the measured Received Signal Strength Indication (RSSI) aiming at removing potential ambiguities in data captured by the multiantenna system has been developed and integrated. The animal tracking system has been largely tested on phantom mice in order to verify its ability to precisely localize each subject and to reconstruct its path. The achieved and discussed results demonstrate the effectiveness of the proposed tracking system.

Improved Reception of In-Body Signals by Means of a Wearable Multi-Antenna System

High data-rate wireless communication for in-body human implants is mainly performed in the 402–405 MHz Medical Implant Communication System band and the 2.45 GHz Industrial, Scientific and Medical band. The latter band offers larger bandwidth, enabling high-resolution live video transmission. Although in-body signal attenuation is larger, at least 29 dB more power may be transmitted in this band and the antenna efficiency for compact antennas at 2.45 GHz is also up to 10 times higher. Moreover, at the receive side, one can exploit the large surface provided by a garment by deploying multiple compact highly efficient wearable antennas, capturing the signals transmitted by the implant directly at the body surface, yielding stronger signals and reducing interference. In this paper, we implement a reliable 3.5 Mbps wearable textile multi-antenna system suitable for integration into a jacket worn by a patient, and evaluate its potential to improve the In-to-Out Body wireless link reliability by means of spatial receive diversity in a standardized measurement setup. We derive the optimal distribution and the minimum number of on-body antennas required to ensure signal levels that are large enough for real-time wireless endoscopy-capsule applications, at varying positions and orientations of the implant in the human body.

EXPERIMENTAL CHARACTERIZATION OF WIRELESS MIMO CHANNEL AT 5.8 GHZ IN UNDERGROUND GOLD MINE

This paper presents analysis results relative to an underground MIMO channel. Measurement campaigns were conducted in a former gold mine at a center frequency of 5.8GHz under Line- Of-Sight (LOS) scenario. Extracted data have been processed to obtain the relevant statistical parameters of the channel. The resulting propagation behavior difiers from frequently encountered in more typical indoor environments, such as o-ces and corridors. Indeed, the path loss exponent is less than 2 in MIMO conflguration due to the large number of scatters that increase the received power when compared to the free-space case. Moreover, there has been a signiflcant increase in spectral e-ciency, when using MIMO technique. Hence, according to calculated statistical parameters, wireless link performance is improved through the use of the MIMO scheme. All in all, multi antenna systems present an ideal alternative for future underground communication systems.

Performance Analysis of Multi-Carrier Two-Way Cooperative Communication with Relay Selection Diversity

Cooperative communication provides most of the advantages as multi-antenna systems due to availability of independent propagation paths between mobile terminals and the base station. In this paper we investigate the performance of Multi-carrier Two-way Two-hop (TW-TH) cooperative communication network in the presence of Rayleigh fading channel. We analyze a simple relay selection diversity scheme in TW-TH cooperative network. The two power allocation schemes with relay selection are discussed. Performance analysis shows that relay selection diversity scheme provides better performance than fixed relaying regardless of the availability of direct path between users.

Zero-Forcing Beamforming in Multiuser MISO Downlink Systems Under Per-Antenna Power Constraint and Equal-Rate Metric

In this paper, we analyze the average sum rate of downlink multi-antenna systems with zero-forcing beamforming (ZFBF). In practical implementations, each antenna is equipped with its own power amplifier and is limited individually by linearity of the amplifier. Thus, this paper adopts a more realistic per-antenna power constraint instead of conventional sum-power constraint on transmit antennas. To this end, we first show that a distribution of the received signal-to-noise ratio (SNR) of the ZFBF scheme with per-antenna power constraint and equal-rate metric can be approximated as a minimum of chi-square random variables. Based on this result, we present an accurate formula of the average sum rate in a closed form. Furthermore, employing extreme value theory, an expression of the asymptotic average sum rate with large numbers of transmit antennas and users is derived from the limiting distribution of the received SNR. Simulation results verify the validity of our analysis even with not so large numbers of transmit antennas and users.

The Optimal Antenna Layout for Maximum Ergodic Capacity of MISO Beamforming System

The performance of the multiantenna systems can be deeply affected by the antenna layout, that is, the placement of the antenna elements in a given area. This paper focuses on the optimal antenna layout which can maximize the ergodic capacity of a multi-input single-output (MISO) beamforming system. Since the optimization problem cannot be solved analytically, we use simulated annealing (SA) algorithm to search for the optimal antenna layout. The results show that the optimal antenna layout depends highly on the power azimuth spectrum (PAS) distribution and power elevation spectrum (PES) distribution. In the three-dimensional (3D) space uniformly scattering environment, the optimal antenna layout will locate the antenna elements on the surface of a sphere. When the scattering is concentrated in a two-dimensional (2D) plane, the circular layout is the optimal and finally, when there is no scattering (single plane wave), the optimal layout is the nonuniform linear array.

Cooperative MIMO in wireless networks: recent developments and challenges

Cooperative multiple-input multiple-output (CMIMO) is a form of cooperative communications. CMIMO emulates the functionality of multi-antenna systems by grouping wireless devices to operate as virtual multi-antenna nodes. Its main objectives are to boost network throughput, conserve energy, and improve network coverage. In this article, we discuss recent applications of CMIMO in contemporary wireless networks, including wireless sensor, mobile ad hoc, wireless LAN, cognitive, and cellular networks. We first review CMIMO techniques at the physical layer. We then focus on state-of-the-art approaches for realizing CMIMO at the network layer, and classify these approaches based on their objectives and application scenarios, and how they exploit CMIMO gains. We highlight several open issues that present challenges to practical deployment of CMIMO.

A Remark on Spatial Correlation Coefficient Focusing on Propagation Channels for Evaluating Multi-Antenna Systems

A Remark on Spatial Correlation Coefficient Focusing on Propagation Channels for Evaluating Multi-Antenna Systems

A NOVEL DECOUPLING NETWORK USING PARALLEL COUPLED LINES FOR INCREASING THE PORT ISOLATION OF TWO COUPLED ANTENNAS

A compact decoupling network for enhancing the ports isolation of two coupled antennas is proposed in this letter. Parallel coupled lines (PCLs) and transmission lines (TLs) with difierent electrical lengths are considered to control the magnitude and phase of this decoupling network, respectively. The coupling coe-cient of the PCLs is adjusted with various line widths and coupled gaps so that the magnitude of this network will be equal to that of the coupled antennas. And the electrical length of the series TLs can be controlled to make the signals of coupled antennas and decoupling network out of phase. Thus, the mutual coupling between the coupled antennas can be canceled. A prototype is fabricated on a RO4003 print circuit board (PCB) for demonstration. The measured results agree quiet well with the simulation ones. High antenna isolation and good matching are simultaneously achieved at the center frequency, i.e., 925MHz for global system mobile communications (GSM) which shows the compact decoupling network is suitable for reducing the isolation of size limited multi-antenna systems.