Showing papers on "Active antenna published in 2014"

Silicon-based broadband antenna for high responsivity and polarization-insensitive photodetection at telecommunication wavelengths

Abstract: Although the concept of using local surface plasmon resonance based nanoantenna for photodetection well below the semiconductor band edge has been demonstrated previously, the nature of local surface plasmon resonance based devices cannot meet many requirements of photodetection applications. Here we propose the concept of deep-trench/thin-metal (DTTM) active antenna that take advantage of surface plasmon resonance phenomena, three-dimensional cavity effects, and large-area metal/semiconductor junctions to effectively generate and collect hot electrons arising from plasmon decay and, thereby, increase photocurrent. The DTTM-based devices exhibited superior photoelectron conversion ability and high degrees of detection linearity under infrared light of both low and high intensity. Therefore, these DTTM-based devices have the attractive properties of high responsivity, extremely low power consumption, and polarization-insensitive detection over a broad bandwidth, suggesting great potential for use in photodetection and on-chip Si photonics in many applications of telecommunication fields.

Use of SSK Modulation in Two-Way Amplify-and-Forward Relaying

Abstract: Space-shift keying (SSK) modulation is a novel multiple-input-multiple-output (MIMO) technique, which activates only a single antenna for transmission at any time instant and uses the index of this active antenna to implicitly convey information. In this paper, a pragmatic communication strategy for the use of SSK modulation in two-way amplify-and-forward (AF) relaying is proposed. Specifically, the transceiver sends the signal by employing SSK modulation and detects the signal based on the maximal-ratio combining principle. By considering a Nakagami- m fading environment, upper bounded and asymptotic bit error probabilities (BEPs) are both derived in closed form. The optimal power allocation problem in the minimization of the average BEP is also addressed. Finally, Monte Carlo simulations are conducted to verify the accuracy of the analysis.

Downlink Vertical Beamforming Designs for Active Antenna Systems

Abstract: In this paper, we study a vertical beamforming technique for multiple-input multiple-output downlink multi-user systems. In general, the transmit antenna gain is controlled by adjusting the boresight of antennas in directional antennas, and thus the cell average rate varies according to the angle of the boresight. First, we compute the tilting angles for directional antenna systems which maximize the cell average rate. To this end, the probability density function of a three-dimensional user distribution is derived. Based on the result, we analyze the average rate gain of active antenna systems over passive antenna systems for a single user case. Furthermore, for a multi-user active antenna system, beamforming designs to maximize the weighted sum rate are proposed by optimizing the transmit antenna gain and power allocation. Since finding joint optimal parameters requires prohibitively high computational complexity, we separate the optimization problem into two sub-problems of the vertical beamforming and the power allocation. Then a simple vertical beamforming algorithm based on a high signal-to-noise ratio assumption is presented. Also, for a multi-user passive antenna system, we provide a beamforming scheme based on a multi-sector concept. Simulation results show that the proposed beamforming schemes outperform the conventional beamforming schemes.

Large scale antenna system with hybrid digital and analog beamforming structure

Abstract: Large scale antenna systems (LSAS) are expected to significantly enhance the energy efficiency (EE) and spectrum efficiency (SE) of wireless communication systems. However, there are many open issues regarding the implementation of digital beamforming (BF) structures: calibration, complexity, and cost. In a practical LSAS deployment, hybrid digital and analog BF structures with active antennas can be an alternative choice. In this paper, an N (the number of transceivers) by M (the number of active antennas per transceiver) hybrid BF structure is investigated, where the analog BF is performed per transceiver and digital BF is performed across N transceivers. Analysis of the N by M BF structure includes: the optimal analog and digital BF design, EE-SE relationship at the green point (i.e. the point with highest EE) in EE-SE curve, impact of N on EE performance at a given SE value, and impact of N on the green point EE. Numerical simulations are provided to support the analysis.

Energy efficiency comparison of massive MIMO and small cell network

Abstract: In this paper, we compare the average energy efficiency (EE) of massive MIMO system and small cell network (SCN) under the conditions of identical user density, antenna density and data rate requirements, where the uplink and downlink training overhead as well as multi-cell power control are taken into account. Our analysis shows that the average transmit power of SCN decreases faster than massive MIMO as the antenna density increases. Moreover, massive MIMO achieves a higher average EE than SCN if its power consumption except the power for transmitting data is very low or the data rate requirement is very high. Considering that in SCN with large number of base stations (BSs) the opportunity for turning some BSs into idle mode is higher, massive MIMO exhibits higher EE only if its circuit power of each active antenna is lower than that for each antenna at an idle small BS. If antenna idling is allowed for massive MIMO, massive MIMO will be more energy efficient than SCN when the former has smaller circuit power for each idling antenna.

Pattern-Reconfigurable Self-Oscillating Active Integrated Antenna With Frequency Agility

Abstract: A frequency-agile pattern-reconfigurable self-oscillating active integrated antenna (AIA) is investigated in this paper. With the aid of two PIN diodes and a varactor, the proposed active antenna shows pattern reconfigurability and frequency tunability at the same time. The antenna, composed of two monopoles and a semi-ring radiator, can be switched between four states, with two featuring omnidirectional patterns and the other two having end-fire radiation. The polarizations of the two omnidirectional states are spatially orthogonal to each other. By embedding a varactor diode, the voltage-controlled tuning range is from 4.27 to 4.94 GHz, while the effective isotropic radiated power (EIRP) varies from 5.4 to 9.3 dBm. The phase noise is better than ${-}102.7$ dBc/Hz at a 1-MHz offset from the carrier frequency.

Active antenna adapted for impedance matching and band switching using a shared component

Abstract: An active antenna and associated circuit topology is adapted to provide active impedance matching and band switching of the antenna using a shared tunable component. Using a shared tunable component, such as a tunable capacitor or other tunable component, the antenna provides a low cost and effective active antenna solution. In certain embodiments, one or more passive components can be further utilized to design band switching of the antenna from a first frequency to a second desired frequency.

Active antenna system

Abstract: The object of the present invention is to provide an active antenna system which is flexibly configurable and efficient in operation. According to a first aspect of the present invention an active antenna system comprises a radio equipment having a plurality of transceiver modules, each transceiver module being connected to at least one antenna, and a radio equipment control unit having a hub being connected to the transceiver modules via an antenna interconnect. The hub is embodied for receiving base band signals via the antenna interconnect from the transceiver modules and to extract channel signals from the received base band signals. As the hub is arranged in the radio equipment control unit which is part of a base station the base band signals are transmitted to the radio equipment control unit without extracting the channel signals. This allows easily to distribute the base band signals on several data connections, particularly several antenna cables, of one antenna interconnect. This results in a reduced information loss and minimizes the requirements for the transmission capacity of a single data connection of the antenna interconnect between the radio equipment control unit and the radio equipment. The radio equipment control unit does receive all the information which is originally received by the transceiver modules.

Active antenna system and methods of testing

Abstract: An active antenna test system is described. The active antenna test system comprises an active antenna unit comprising: a plurality of antenna elements; at least one processor; a plurality of transceiver modules operably coupled to the at least one processor and arranged to receive at least one first baseband signal for transmission via at least one of the plurality of antenna elements and arranged to pass at least one second baseband signal thereto received and down-converted from at least one of the plurality of antenna elements; and at least one switching module operably coupling the plurality of antenna modules to the plurality of transceiver modules. The active antenna test system also comprises at least one communication test equipment, such as a radio frequency, RF, test module and at least one baseband processor. The active antenna unit further comprises at least one externally connectable radio frequency, RF, test port operably coupled to the at least one switching module and arranged to externally couple the at least one communication test equipment to at least one of the plurality of transceiver modules for conductive testing.

A Planar Wideband Dual-Polarized Array for Active Antenna System

Abstract: A ±45° polarized wideband slot array antenna is proposed for active antenna system (AAS). The proposed array has a planar structure that integrates all the elements on a single substrate. Metal columns are used to reduce the coupling between adjacent elements. A prototype of a 2 × 2 array antenna is fabricated and measured. The measured results show that the proposed array covers the bands LTE2300 (2300-2400 MHz) and LTE2500 (2500-2690 MHz), and the polarization isolation is higher than 30 dB while the coupling between elements is less than -22 dB.

Reconfigurable multi-mode active antenna system

Abstract: A reconfigurable antenna system is described which combines active and passive components used to impedance match, alter the frequency response, and change the radiation pattern of an antenna. Re-use of components such as switches and tunable capacitors make the circuit topologies more space and cost effective, while reducing complexity of the control signaling required. Antenna structures with single and multiple feed and/or ground connections are described and active circuit topologies are shown for these configurations. A processor and algorithm can reside with the antenna circuitry, or the algorithm to control antenna optimization can be implemented in a processor in the host device.

Antenna array and method for synthesizing antenna patterns

Abstract: An antenna array having a plurality of antenna elements is disclosed. The antenna array comprises: a plurality of transceiver modules; an active antenna element subset of the plurality of antenna elements, wherein the active antenna element subset comprises at least one active antenna element being actively coupled to an associated transceiver module of the plurality of transceiver modules; and at least one passively combined sub-array of at least two antenna elements of the plurality of antenna elements. A method for generating antenna patterns with the antenna array is also disclosed.

Full-dimensional MIMO for future cellular networks

Abstract: Full-dimensional multiple input multiple output (FD-MIMO) is a practical implementation of massive MIMO in cellular communication systems. FD-MIMO relies on an active two-dimensional antenna grid at the base stations and harvests the benefits of both azimuth and elevation beamforming. This paper briefly introduces the concept of FD-MIMO, and surveys the recent research results and applications of active antenna systems (AAS) technology. The key concepts discussed range from antenna patterns and channel modeling to vertical sectorization and heterogeneous networks deployment. The paper focuses on the benefits of FD-MIMO in an urban environment with high rises and three-dimensional user deployment. It demonstrates the importance of FD-MIMO in enhancing the performance of cellular networks.

A 314 GHz, fully-integrated SiGe transmitter and receiver with integrated antenna

Abstract: We present a 314 GHz transmitter and receiver chipset which is implemented in an advanced SiGe HBT platform, and which has on-chip antennas. The transmitter uses an active antenna structure, where the generated on-chip signal is directly fed into the antenna. The receiver consists of a novel sub-harmonic resistive mixer with an on-chip high-power differential signal source feeding the LO port. A test link which directly connects the transmitter to the receiver was also implemented as a reference for characterization. This reference circuit enables a simple and accurate measurement method for conversion loss and antenna gain by omitting external high frequency signal sources. To further facilitate the characterization, the utilized on-chip signals were implemented and tested separately as well. The receiver achieves 22.5 dB conversion loss and the transmitter generates a signal power of -8 dBm at 314 GHz. On-die end-fire antennas were designed for both transmit and receive paths, and utilize a substrate etching technology to boost performance. This work demonstrates the feasibility of fully-integrated and compact sub-mmW transceiver implementations using SiGe technology.

Practical active antenna evaluation using the two-stage MIMO OTA measurement method

Abstract: This paper discusses practical and cost-effective ways of evaluating the performance of active antenna array systems (AAS) using the two-stage MIMO OTA measurement method. The paper first introduces the concept of the two-stage method which is based on a first stage of antenna pattern measurement followed by a second stage of throughput measurement using a signal generated by convolving the device antenna pattern with the desired spatial channel model. The resulting signal is applied to the DUT either through a conducted or radiated connection. The radiated version of the two-stage method was recently approved by 3GPP in Technical Report 37.977 v12.0.0 [1]. The primary advantage of the two-stage method is that arbitrary 2D or 3D spatial channel models can be emulated without the need for the conventional multi-probe anechoic chamber approach which is significantly more complex and expensive. The extension of the two-stage method to active antenna systems is possible due to the unique ability of the two-stage method to provide intermediate antenna pattern measurements as part of the process. By measurement of a finite set of possible antenna pattern states the performance of the device for any orientation in the chosen spatial channel model can be evaluated for each antenna state and the optimum performance identified. The antenna state which is shown to provide the best performance can then be compared with the state chosen by the device when a known channel is applied through any particular state. To allow active antenna analysis to work, a proprietary feedback mechanism between the device and the test system is necessary to indicate the device's chosen antenna pattern to the test system. The described concepts apply to both mobile devices and base stations, and are particularly suited to the latter due to the size of the device which makes evaluation in a 2D or 3D anechoic chamber impractical.

RISAT-1: Configuration and performance evaluation

Abstract: Radar Imaging Satellite (RISAT-1) was launched on 26th April, 2012 and is available to international SAR community and researchers as a source of multi resolution/multi-swath/multi-polarisation SAR data. The first satellite, RISAT-1, carries a multi-mode Synthetic Aperture Radar (SAR) in C-band as the sole payload. RISAT-SAR payload supports variety of imaging modes e.g., stripmap, scanSAR and spotlight. All these imaging modes can be operated in Hybrid polarimetry mode also, making it the first of its kind. The payload is based on active antenna array technology. The active antenna has nominal aperture of 6 m×2m, consisting of 12 tiles which are grouped into 3 panels. The RISAT-1 spacecraft has been built around the SAR payload in order to optimise the spacecraft weight and structure. The satellite is placed in a sun-synchronous orbit with 6 am-6 pm equatorial crossing, to maximize solar power availability. Initial performance assessment indicates very satisfactory performance of the SAR system of RISAT-1 in terms of image quality, calibration, geometric fidelity and consistent product performance and active antenna pattern synthesis. Already from September 2012, data products are available operationally from National Remote Sensing Centre, Hyderabad.

Antenna system and method for full duplex wireless transmission with channel phase-based encryption

Abstract: An antenna assembly includes a first active antenna element and a second active antenna element, each of which may be a dipole. A first set of independently-switchable radio-frequency reflectors are positioned around at least the first active antenna element. These first switchable radio-frequency reflectors may also be positioned around the second active antenna element. Alternatively, a second set of independently-switchable radio-frequency reflectors may be positioned around the second active antenna element. The switchable reflectors enable controlled perturbation of the communication channel between the antenna assembly and a remote communications node, enabling securely encrypted communications.

Microstrip ring resonator based frequency reconfigurable band-pass filters at K-band

Abstract: In this contribution two planar microstrip band-pass filters based on closed loop resonators with reconfigurable center frequency are proposed at K-band. Two geometries, a square-ring and a meander loop, are closely investigated. The frequency reconfigurability is achieved by means of PIN diodes. The filters are designed for and fabricated on a standard printed circuit board technology. Dual-mode resonators are used to obtain a compact design suitable for integration into an active antenna frontend. The paper presents the filter design, the tuning range, an analysis of the occurring losses, and the verification through simulation and measurement.

Rfid system with time slot interleaving

Abstract: A method for interleaving time slots in a multi-antenna system for communication with RFID tags is disclosed. An example is shown for an eight antenna system. A first four antennas arranged side-by-side are sequentially energized to interrogate RFID transponders. A second set of four antennas arranged side-by-side, the first of which is adjacent to the last of the first set of antennas. A four-antenna sequence is performed for the first four antennas and a second four antenna sequence is performed for the second set of antennas. The first and second four antenna sequences are offset by only a marginal amount, sufficient to ensure that a transponder signal received four antennas away from an active antenna is not acknowledged because the receive window for the non-active antenna is delayed.

Active antenna system enhancement for supporting Licensed Shared Access (LSA) concept

Abstract: Mobile and wireless communication networks will need to cope with the tremendous increase in data traffic anticipated over the next decade. Beyond the levers of increased network densification and enhanced spectral efficiency more radio spectrum is clearly needed for mobile networks to fulfill capacity and coverage demands. Finding spectrum without existing incumbent usage in a harmonized manner becomes increasingly challenging. Spectrum sharing techniques can be used to optimize spectrum utilization across multiple services to share the same frequency band in a controlled manner. Another emerging technique to enhance cellular network capacity is smart antennas that can flexibly control radiation patterns. These new spectrum efficiency enhancements should be deployed in a way that requires minimum changes to the features and the architecture of the systems involved. In this paper, we concentrate on the Licensed Shared Access (LSA) concept which in recent years has received considerable interest in both European and USA regulation and standardization. We discuss how smart antennas technologies and Active Antenna System (AAS) in particular could be used to enhance LSA systems. Finally, we propose a system architecture and implementation scenarios for LSA that provides spectrum exclusion zone reduction and interference detection by using Active Antenna System.

Comparison and Extension of Existing 3D Propagation Models with Real-World Effects Based on Ray-Tracing

Abstract: The next generation of cellular network deployment is heterogeneous and temporally changing in order to follow the coverage and capacity needs. Active Antenna Systems allows fast deployment changes by cell shaping and tilt adaptation which have to be controlled in self-organized manner. However, such kind of automated and flexible network operations require a Self Organizing Network (SON) algorithm that works based on network performance parameters being partly derived from the radio measurements. Thus, appropriate radio propagation models are not only needed for network planning tools but also for simulative lab tests of the developed SON algorithm controlling the flexible deployment changes enabled by Active Antenna Systems. In this paper, an extension of the existing 3D propagation model is proposed in order to incorporate the propagation condition variation effects, not considered so far, by changing antenna beam orientation like antenna tilting or when users are distributed in the third dimension (height) in multi-floor scenarios. Ray tracing based generated propagation maps that show the realistic propagation effect are used as 3D real world reference for investigation and model approval.

An 8×8 MIMO 3-axis weighted polarization active antenna for wearable radio applications

Abstract: This paper presents a 3-axis weighted-polarization active antenna in order to realize ultra high-speed and high-capacity mobile communications. The proposed antenna is comprised of three orthogonal antennas, two of which can be selected according to a weight function in different situations. The weight function is created based on the variation of cross polarization power ratio (XPR) and the inclination angle of an antenna depending on the propagation environment and the human motion. The result shows that a high level of the channel capacity can be obtained even when the variation of XPR and the antenna inclination angle are taken into consideration simultaneously, demonstrating that gigabit high-speed communication can be realized using the proposed antenna.

A method for beamforming a beam using an active antenna

Abstract: The present invention relates to a method for beamforming a beam using an active antenna having predetermined aperture data comprising M x N dual polarized antenna subarrays within an aperture, each dual polarized antenna subarray comprising a first antenna subarray having a first polarization and a second antenna subarray having a second polarization non-parallel with the first polarization. The method comprises: selecting number of antenna ports, each antenna port being adapted to generate a separate beam using a combination from the first antenna subarray and/or the second antenna subarray; selecting port properties, comprising target beamwidth for each separate beam and desired polarization between beams; and determining port partitioning based upon aperture data and port properties for each antenna port, to adjust an effective length of the aperture over which the beam is created and thereby defining which first antenna subarray(s) and/or second antenna subarray(s) to use for each antenna port.

Active antenna system (AAS) capabilities for 5G systems: A field study of performance

Abstract: Enhanced antenna technologies will be key enabling factors in the development of 5th-generation (5G) systems that will achieve significant improvements in system capacity. This paper presents a practical performance evaluation of an active antenna system (AAS) that can lead to high-capacity gain with vertical sectorization (VS). Active antennas have flexible radiation pattern control for adapting to changing situations in mobile networks. This study shows the capabilities of an AAS to improving cellular network capacity in a real High-Speed Packet Access (HSPA) network. The field trial results indicate that the AAS technology can offer 84.6% capacity gains in the downlink direction. Thus AAS technology is a promising development for 5G mobile cellular systems that demand more capacity.

First Radio Astronomy Examination of the Low-Frequency Broadband Active Antenna Subarray

Abstract: We present the 25-element active antenna array and its remote control in the framework of the GURT project, the Ukrainian Radio Telescope of a new age. To implement beamforming, the array is phased with the help of discrete cable delay lines in analog manner. The remote control of the array is carried out through the paired encoder and decoder that can transmit parallel data about antenna codes serially. The microcontroller provides the online interaction between personal computer and beamformers with the help of the encoder-decoder system through wires or wireless. The antenna pattern has been measured by radio astronomy methods.

Load Balancing with Antenna Tilt Control in Enhanced Local Area Architecture

Abstract: Small cell is an attractive and promising technology for improving capacity in traffic hotspots using cell densification. We consider the traffic load balancing problem for small cells under the enhanced Local Area (eLA) architecture utilizing the flexible 3-dimensional (3D) beamforming facilitated by the adoption of the active antenna system (AAS) at base stations (BSs). Different load balancing methods based on combinations of cell association algorithms and antenna tilt adjustment schemes are proposed and evaluated via system level simulations. Results show the potential gain of traffic load balancing with 3D beamforming in terms of cell edge user throughput. In particular, for the enhanced load balancing cell association combined with UE (user equipment)-specific tilting scheme, significant cell edge user throughput improvements can be achieved while good average cell throughput performance can still be maintained.

Field trial results for vertical sectorization in LTE network using Active Antenna System

Abstract: Previous work has reported that vertical sectorization can efficiently improve the capacity of LTE network using Active Antenna System (AAS) based on simulation results, however, its performance in real-world scenario still needs to be evaluated and verified for future deployment. Thus, this study conducts an evaluation of vertical sectorization in LTE field trial with single user. The field trial results show that the average downlink throughput of the single user is reduced compared to the one of traditional network, which results in the deterioration of user experience. Furthermore, we examine field data and antenna parameters, and verify that the co-frequency interference between the inner and outer cells is the main reason for average downlink throughput decrease in field trial. Obviously, without proper interference suppression or can-celation mechanisms, the vertical sectorization can not improve the user experience. Therefore, some practical suggestions on the deployment of vertical sectorization in LTE network are proposed.

Full-function path recognition charging double-source multi-frequency read-write system and method for expressway

Abstract: The invention provides a full-function path recognition charging double-source multi-frequency read-write system and method for an expressway. The system comprises a double-source reader-writer, a passive antenna, an active antenna, a desktop type card sender, a passive double-frequency card and an active double-frequency card. The MTC mode and the ETC mode are integrated, the path recognition charging function for all vehicles on the expressway is really achieved on the basis of not replacing an existing expressway charging mode, the communication frequency band of a passive module of the double-source reader-writer included in the full-function path recognition charging double-source multi-frequency read-write system and method for the expressway is 840-845 MHz or 920-925 MHz, and the national standard of automobile electronic marks (electronic number plates) is also met.

Multifrequency Oscillator-Type Active Printed Antenna Using Chaotic Colpitts Oscillator

Abstract: This paper presents a new concept to realize a multifrequency Oscillator-type active printed monopole antenna. The concept of period doubling route to chaos is exploited to generate the multiple frequencies. The chaotic Colpitts oscillator is integrated with the printed monopole antenna (PMA) on the same side of the substrate to realize an Oscillator-type active antenna where the PMA acts as a load and radiator to the chaotic oscillator. By changing the bias voltage of the oscillator, the antenna can be made to operate at single or multiple frequencies. To test the characteristics of the antenna at single and multiple frequencies of operation, two similar prototype models of printed monopole broadband antennas are developed. One of these antennas used at transmit side is fed by the chaotic Colpitts oscillator while the other is used as the receive antenna. It is observed that the antenna receives single or multiple frequencies simultaneously for particular values of the bias voltage of the oscillator at the transmit end.