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1.	Amani, Navid, 1985, et al. (författare) MIMO Channel Capacity Gains in mm-Wave LOS Systems with Irregular Sparse Array Antennas 2017 Ingår i: APWC 2017. ; 2017-January Konferensbidrag (refereegranskat)abstract This paper investigates potential advantages of linear irregular sparse antenna arrays over their regular counterparts in a mm-wave line-of-sight (LOS) multiple-input multiple-output (MIMO) scenario. The comparison is based on numerical computations of MIMO eigenvalues of the corresponding channel matrices and the resulting channel capacity. Identical linear antenna arrays are assumed at the transmitter and the receiver sides. The compared regular and irregular arrays have an equal aperture length. Mutual coupling between elements within an array is assumed negligible due to the array sparsity. A 4×4 MIMO channel is studied, where we change the position of the two inner elements to obtain irregularly spaced arrays. It is shown that for some specific distances between TX and RX, the irregular array distribution can significantly improve the channel capacity in LOS. This observation opts for reconfigurable array designs.
2.	Amani, Navid, 1985, et al. (författare) Network model of a 5G MIMO base station antenna in a downlink multi-user scenario 2018 Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741 Konferensbidrag (refereegranskat)abstract A system level network model of a 5G base station antenna (BSA) with massive multiple-input multiple-output (MIMO) capabilities is presented that incorporates antenna mutual interaction and signal processing aspects. The combined transmitter-channel-receiver in such a system is modeled by cascading Z-matrices to interrelate the transmitter and receiver port voltages/ currents to one another. The developed model is then subjected to the zero-forcing (ZF) beamforming algorithm to compute the per-antenna transmit power for a specific minimum signal level at the receiver as well as the required BSA effective isotropic radiated power (EIRP). The presented initial results show that in a line-of-sight (LOS) environment the required EIRP to achieve a 1 Gbps bitrate user link in a 15-200 m coverage ranges from 25-48 dBm, which increases to 31-54 dBm after incorporating first-order mutual coupling effects among the BSA elements.
3.	Amani, Navid, 1985, et al. (författare) Per-Antenna Power Distribution of a Zero-Forcing Beamformed ULA in pure LOS MU-MIMO 2018 Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 22:12, s. 2515-2518 Tidskriftsartikel (refereegranskat)abstract An analytical model is presented to determine the per-antenna power distribution of a beamformed M-element uniform linear array (ULA) as a base station antenna (BSA). The analysis assumes a single sector cell serving two user equipments (UEs) in a downlink multiuser multiple-input multiple-output (MU-MIMO) system employing zeroforcing (ZF) transmission. Determinative design parameters of the BSA configuration are identified. Afterwards, their effects on the power spread across the array are investigated when the positions of the users are random and they are uniformly distributed over the cell. It is shown that the power distribution across the ULA antenna aperture is a periodic function whose characteristics mainly depend on the angular separation of two UEs and the number of BSA elements. A significant variation between ULA input powers is seen to occur if the number of elements in the ULA is smaller than one period of this power distribution function. In order to mitigate the dynamic range of the power variation across the array, an upper bound for the inter-element spacing, depending on the field-of-view (FoV) of the BSA, is defined. It is shown that, in a 20-element ULA, increasing the inter-element spacing from 0.5-wavelength to 1.4-wavelength reduces the power variation from 19 dB to 10 dB for differentiating two close-by UEs with 1 degree angular separation.
4.	Bagheri, Alireza, et al. (författare) A ±45° Dual-Polarized Antenna for 5G mmWave Applications Based on Gap Waveguide Technology 2019 Ingår i: 2019 International Symposium on Antennas and Propagation, ISAP 2019 - Proceedings. Konferensbidrag (refereegranskat)abstract A ±45° dual-polarized antenna is designed based on the gap waveguide technology which offers a low loss and easy-to-manufacture solution at the mmWave frequencies. Dual-polarized antennas help to increase the capacity and coverage of a wireless system and also decrease the overall cost. Two parallel arrays of 8 slots each are employed to create the orthogonal polarizations. The antenna operates in the 24.25 - 27.25 GHz frequency band. The simulated average gain of each polarization is 14.5 dBi while achieving a cross-polarization isolation of at least 15 dB.
5.	Bagheri, Alireza, et al. (författare) MmWave array antenna based on gap waveguide technology for 5G applications 2019 Ingår i: Proceedings of the 2019 21st International Conference on Electromagnetics in Advanced Applications, ICEAA 2019. ; , s. 492-494 Konferensbidrag (refereegranskat)abstract The gap waveguide technology has been shown to provide low loss and easy-to-manufacture antenna solutions in the mmWave frequencies. A gap waveguide array antenna with scanning ability within ±45° designed with focus on 5G applications is presented here. The computed active reflection coefficient of the array is less than -10 dB for all scan angles and the broadside gain is 23 dBi. The proposed antenna can be integrated with active components to increase EIRP and coverage range.
6.	Bencivenni, Carlo, 1986, et al. (författare) Effects of Regular and Aperiodic Array Layout in Multi-User MIMO Applications 2017 Ingår i: IEEE Antennas and Propagation Society International Symposium. - 1522-3965. - 9781538632840 ; 2017-January, s. 1877-1878 Konferensbidrag (refereegranskat)abstract In MIMO applications, antenna arrays adopt a uniform regular lattice. However, in phased array applications, it is a well-known fact that aperiodic or irregular arrays can offer several advantages. In this paper, we present initial investigations on the effects of regular and aperiodic layouts in Multi-User MIMO applications. We aim at explaining and providing an intuitive understanding on why aperiodic arrays are superior to regular ones. Additional results and quantification of the advantages will be presented in an upcoming journal publication.
7.	Carlsson, Jan, 1962, et al. (författare) Reverberation chamber for OTA measurements: The history of a dream! 2017 Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. - 9788890701870 ; , s. 237-241 Konferensbidrag (refereegranskat)abstract In the late 1990's Professor Per-Simon Kildal got the idea that reverberation chambers could be used for characterizing small antennas and mobile devices. Many thought the idea was crazy but he was persistent and worked hard to realize his dream to build a small chamber that could be used by the wireless industry. This paper gives a short history of the research at Chalmers and the creation of the company Bluetest that both were instrumental for realizing the dream.
8.	Glazunov, Andres Alayon, 1969, et al. (författare) A spherical probability distribution model of the user-induced mobile phone orientation 2018 Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 6, s. 37185-37194 Tidskriftsartikel (refereegranskat)abstract This paper presents a statistical modeling approach of the real-life user-induced randomness due to mobile phone orientations for different phone usage types. As well-known, the radiated performance of a wireless device depends on its orientation and position relative to the user. Therefore, realistic handset usage models will lead to more accurate over-the-air characterization measurements for antennas and wireless devices in general. We introduce a phone usage classification based on the network access modes, e.g., voice (circuit switched) or non-voice (packet switched) services, and the use of accessories, such as wired or Bluetooth handsets, or a speaker-phone during the network access session. The random phone orientation is then modeled by the spherical von Mises-Fisher distribution for each of the identified phone usage types. A finite mixture model based on the individual probability distribution functions and heuristic weights is also presented. The models are based on data collected from built-in accelerometer measurements. Our approach offers a straightforward modeling of the user-induced random orientation for different phone usage types. The models can be used in the design of better handsets and antenna systems as well as for the design and optimization of wireless networks.
9.	Glazunov, Andres Alayon, 1969, et al. (författare) Capacity Gains of (3 × 3)×(3 × 3) MIMO Fixed Links with Planar Aperiodic Sparse Arrays in Pure-LOS Channels 2018 Ingår i: Proceedings of the 2018 8th IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC 2018. ; , s. 734-736 Konferensbidrag (refereegranskat)abstract © 2018 IEEE. Presented is an analysis of the topology of a 3 × 3 element planar (square) array antenna with vertically polarized isotropic antenna elements. The focus has been on fixed multiple-input multiple-output communication links in pure line-of-sight channels. An empirical equation is presented for the mid-elements' relative position on the sides of the square array achieving near-optimal (3 × 3) × (3 × 3) multiple-input multiple-output capacity. It is observed that the position is a function of both the separation distance between transmit and receive antennas and the wavelength of the transmit signal in a similar way as for 3 × 3 systems with linear arrays. The capacity gains of the aperiodic planar array over the uniform planar array antenna configurations are presented. It is shown that considerable capacity gains in capacity can be obtained by choosing the right array topology following a simple design rule.
10.	Glazunov, Andres Alayon, 1969, et al. (författare) Devising a Horizontal Chamber Array for Automotive OTA Tests in Random Line-Of-Sight 2016 Ingår i: International Symposium on Antennas and Propagation (ISAP), Hobart, Australia, 9-12 November, 2015. ; , s. Art. no. 7447285- Konferensbidrag (refereegranskat)abstract In this paper we propose an approach to design a horizontal array antenna to reduce the uncertainty of reference measurements in Random Line-Of-Sight Over-The-Air testing in anechoic chambers. The main focus is on wireless communications testing to and from automotive vehicles. The proposed procedure allows to determine the size, the spacing and the number of elements of a horizontal array antenna resulting in an absolute error less than 1 dB. The analysis is based on presenting the output of the ideal digital threshold receiver model of the device under test as a Probability of Detection curve.
11.	Glazunov, Andres Alayon, 1969 (författare) Downlink Massive MIMO performance of a vertically polarized uniform linear array in Random Line-Of-Sight 2016 Ingår i: 10th European Conference on Antennas and Propagation, EuCAP 2016; Davos; Switzerland; 10 April 2016 through 15 April 2016. - 2164-3342. - 9788890701863 ; , s. Art. no. 7481947- Konferensbidrag (refereegranskat)abstract In the present paper we study the downlink performance of a Massive Multi-User Multiple-Input Multiple-Output narrowband system in Random Line-Of-Sight scenarios. We evaluate the ergodic sum rate for the Zero-Forcing and the Matched-Filtering precoders. We consider a single-cell system comprising a base station with 100 Huygens source antenna elements and 10 users each equipped with a single dipole antenna. No coupling effects between the array elements have been assumed. We show that in a Random Line-Of-Sight environment, the MF precoding performance is better than the ZF over a wider range of average per-user signal-to-noise ratio as compared to the i.i.d. case.
12.	Glazunov, Andres Alayon, 1969 (författare) Far-field Reference Distance Criteria for Compact OTA Testing Ranges 2019 Ingår i: 2019 13TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). - 2164-3342. - 9788890701887 Konferensbidrag (refereegranskat)abstract Analyzed are three criteria for the computation of a reference distance marking the start of the far-field region in antenna measurements. The analysis is based on a correction factor for the Friis formula at boresight in the Fresnel zone. Closed form equations are obtained as a function of frequency, the gains of the transmit and receive antennas and a user-defined accuracy factor. Based on the above a far-field reference distance similar to the Fraunhofer distance criterium is defined. The presented results will be essential to design cost-efficient characterization of wireless devices of any size with user-defined accuracy.
13.	Glazunov, Andres Alayon, 1969, et al. (författare) Impact of Azimuthal Antenna Pattern Sampling and Variation on Throughput Measurements 2019 Ingår i: 2019 IEEE Conference on Antenna Measurements & Applications (CAMA). - 9781728123967 ; , s. 167-170 Konferensbidrag (refereegranskat)abstract Presented is a numerical study of the impact of the antenna pattern sampling resolution on the accuracy of Over-The-Air (OTA) throughput measurements. More specifically, a Line-Of-Sight (Random-LOS) testing scenario is addressed. The communication throughput is evaluated as the Probability of Detection (PoD) of a single bitstream based on the ideal digital threshold receiver model. The maximum deviation of throughput efficiency is computed as a function of the azimuthal sampling resolution for various generic antenna gain patterns. The coefficient of variation of the antenna gain pattern is introduced to evaluate the impact of the azimuthal sampling. The presented approach can be used to define the sampling resolution of the throughput performance of a device under test in Random-LOS OTA.
14.	Glazunov, Andres Alayon, 1969 (författare) Impact of deficient array antenna elements on downlink massive MIMO performance in RIMP and random-lOs channels 2018 Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741 Konferensbidrag (refereegranskat)abstract The Over-the-Air (OTA) characterization of large antenna systems need to be time- and cost-efficient. Among others, two potential candidates are OTA measurement environments emulating the Rich Isotropic MultiPath (RIMP) and the Random Line-Of-Sight (Random-LOS) channels. In the present paper we study the capacity loss of downlink massive multi-user multiple-input multiple-output (Massive MIMO) narrowband systems in these channels due to deficient antenna elements. We evaluate the downlink ergodic sum rate for the Zero-Forcing (ZF) and the Matched-Filtering (MF) precoders in these channels. We consider a single-cell system comprising a base station with 50 equidistant isotropic source antenna elements placed λ/2 apart and 5 users each equipped with a single isotropic antenna. No coupling effects between the array elements have been assumed. In the present study we show that both the RIMP and the Random-LOS can be used to identify deficient performance of Massive MIMO arrays.
15.	Glazunov, Andres Alayon, 1969, et al. (författare) Impact of the Spatial User Distribution on the Coverage Antenna Pattern of Maximum Ratio Combining in Random Line-Of-Sight 2015 Ingår i: 9th European Conference on Antennas and Propagation, EuCAP 2015, Lisbon, Portugal, 13-17 May 2015. - 9788890701856 Konferensbidrag (refereegranskat)abstract In this paper we investigate the impact of the spatial user distribution on the Maximum Ratio Combining (MRC) of the output signals from an ideal 4-port antenna. The antenna consists of four elementary Huygens sources operating in Random Line-Of-Sight (RLOS). The antenna is assumed to be wall-mounted. Two specific scenarios for the user distribution are considered, i.e., the 3D hemisphere and a rectangular prism emulating a corridor or a rectangular room. We present simulation results in terms of the cumulative distribution functions corresponding to the resulting polarisation and pattern diversity of 1-bitstream and the corresponding coverage radiation pattern of the 4-port antenna system. We also show that there is an antenna arrangement that maximizes the diversity gain that will be different for different spatial distributions of users.
16.	Glazunov, Andres Alayon, 1969, et al. (författare) Point-to-Point 3 x 3 MIMO Performance Gains with Aperiodic Sparse Arrays in Pure LOS Channels 2017 Ingår i: 2017 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP 2017). - 9781538604656 ; 2017-January Konferensbidrag (refereegranskat)abstract Analyzed is the topology of a 3-element linear array antenna with vertically polarized isotropic antenna elements. The focus has been on point-to-point (PtP) multiple-input multiple output (MEMO) communication over pure line-of-sight (LOS) channels. An empirical equation is presented for the mid element's relative position achieving near-optimal 3 x 3 MIMO capacity. The position is a function of the transmit and the receive antennas separation distance and the wavelength of the transmit signal. The capacity gains of aperiodic over uniform array antenna configurations are presented, which at some distances can be a factor 2.5.
17.	Glazunov, Andres Alayon, 1969, et al. (författare) Reverberating Dreams - the Story of an OTA Chamber 2017 Ingår i: 2017 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETING. - 1522-3965. - 9781538632840 ; 2017-January, s. 239-240 Konferensbidrag (refereegranskat)abstract By the late 90's Prof. Per-Simon Kildal came to the insight that reverberation chambers could be useful tools for characterizing small antennas and wireless devices in multipath channels. This was a revolutionizing idea that was not so well received at first. However, with perseverance, he worked through the challenges to see his dream become a reality. This paper is to recognize Prof. Kildal's contributions carried out at Chalmers, the spin-off company Bluetest, but also the contributions of many other people that have been key to materializing his dream.
18.	Glazunov, Andres Alayon, 1969, et al. (författare) Simulating the MIMO Efficiency of Antennas 2017 Ingår i: 2017 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP 2017). - 9781538604656 ; 2017-January Konferensbidrag (refereegranskat)abstract Presented is a mathematical model to compute the multiple-input multiple-output efficiency of a multiport antenna in the single-user case. The evaluation comprises the performance of a zero-forcing receiver in two limiting propagation scenarios, i.e., the random line-of-sight and the rich isotropic multipath channels.
19.	Glazunov, Andres Alayon, 1969, et al. (författare) Simulations of a planar array arrangement for automotive Random-LOS OTA testing 2016 Ingår i: 2016 10th European Conference on Antennas and Propagation, EuCAP 2016. - 9788890701863 ; , s. 7481285- Konferensbidrag (refereegranskat)abstract We present simulations of near-field plane wave synthesis by a planar array. The focus is on minimization of reference signal errors within the test zone for Random Line-Of-Sight Over-The-Air characterization of wireless devices on cars. The analysis considers the output of the ideal digital threshold receiver model of the device under test as a Probability of Detection curve. The dimensions, the interelement spacings and the number of elements in a planar array comprising Huygens sources are investigated to produce an absolute error less than 0.5 dB.
20.	Glazunov, Andres Alayon, 1969 (författare) Test Zone Characterization in an Automotive Random-LOS OTA Test Setup 2017 Ingår i: PROCEEDINGS OF THE 2017 IEEE-APS TOPICAL CONFERENCE ON ANTENNAS AND PROPAGATION IN WIRELESS COMMUNICATIONS (APWC). - 9781509044542 ; 2017-January, s. 170-173 Konferensbidrag (refereegranskat)abstract Presented is a method to produce a 2D reference test zone for over-the-air measurements in a random line-of-sight environment for vehicular applications. The ideal threshold receiver model is used to design the chamber array at 3 GHz for LTE/LTE-A systems. The analysis focuses on the fluctuations of the reference power measurements at a user-defined probability of detection level of bitstreams. Numerical results of the test zone characterization are presented assuming an ideal anechoic chamber is used.
21.	Glazunov, Andres Alayon, 1969, et al. (författare) Zero-forcing MIMO efficiency in random line-of-sight 2016 Ingår i: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016, Fajardo, Puerto Rico, 26 June - 1 July 2016. - 1522-3965. - 9781509028863 ; , s. 331-332 Konferensbidrag (refereegranskat)abstract We derive the Multiple-Input Multiple-Output (MIMO) efficiency of the Zero-Forcing (ZF) receiver algorithm in Random Line-Of-Sight (Random-LOS). We make use of the Probability-of-Detection (PoD) curves based on the ideal digital threshold receiver model in the derivations. We show that the MIMO efficiency in this case, is mainly determined by two factors: the smallest channel gain of the two available bit streams and the non-orthogonality coefficient. This must be considered when designing antenna systems for efficient communication at higher frequencies since Random-LOS propagation will be dominating.
22.	Hussain, Ahmed, 1985, et al. (författare) Antenna Measurements in Reverberation Chamber Using USRP 2016 Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 64:3, s. 1152-1157 Tidskriftsartikel (refereegranskat)abstract This paper shows that a universal software radio peripheral (USRP) can be used to measure the complete passive over-the-air (OTA) performance of multipart antennas for multiple-input multiple output (MIMO) systems. The passive MIMO OTA measurements are performed in a reverberation chamber using the USRP as a measurement instrument. The total embedded radiation efficiencies, the correlation, and the resulting diversity gain are extracted from transmission measurements only. These are in good agreement with S-parameter measurements (both transmission and reflection) obtained with a vector network analyzer (VNA). The proposed measurement approach involving USRPs provide an economical alternative to these type of measurements as compared to high-end equipment.
23.	Hussain, Ahmed, 1985, et al. (författare) Interpreting the Total Isotropic Sensitivity and Diversity Gain of LTE-enabled wireless devices from Over The Air Throughput Measurements in Reverberation Chambers 2015 Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 3, s. 131-145 Tidskriftsartikel (refereegranskat)abstract The characterization of the performance of wireless devices is the key to developing new RF products conforming to the latest communications protocols. Traditionally, communication performance tests have focused on the RF performance of the tested devices, e.g., smart phones, pads, laptops, etc. More specifically, the focus has shifted from conducted (i.e.,cabled) measurements to more realistic Over-The-Air (OTA)characterization of the RF performance of these devices in transmit or receive mode. For example, the receiver performance of 2G and 3G wireless devices can be measured in terms of the total isotropic sensitivity (TIS) that depends on the antenna and the receiver parts of a wireless device. These measurements can be performed in a reverberation chamber setup. However, standard TIS measurements can be time consuming and do not reflect the actual performance gains of Multiple-Input Multiple-Output (MIMO) antenna systems operating over OrthogonalFrequency Division Multiplexing (OFDM) channels, such asthose encountered in 4G Long Term Evolution (LTE) systems. Therefore, in order to meet both time and cost efficiency requirements, we propose here a new method to determine the TIS, as well as the diversity performance, of an LTE device based on throughput measurements. The proposed method shows that the TIS of an LTE device is characterized much faster directly from OTA throughput measurements than from standard TIS measurements and with excellent accuracy.
24.	Iupikov, Oleg, 1983, et al. (författare) Indoor Received Power Prediction Based on Physical Optics (PO): Simulations and Experimental Validation in Industrial Environment 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. Konferensbidrag (refereegranskat)abstract This study presents an approach based on Physical Optics computations to predict the receive signal power in an indoor environment. The application in focus pertains the development of highly reliable manufacturing industry processes where wireless communications plays a key role. Our proposed numerical method shows a good agreement with measurement data. It is therefore suggested that Electromagnetic modelling based on computationally efficient Physical Optics algorithms can be used as a complement, an alternative or even a replacement for empirical models requiring time consuming measurement campaigns.
25.	Kildal, Per-Simon, 1951, et al. (författare) Optimizing Small Wideband Antenna Performance for Both RIMP and Random-LOS 2015 Ingår i: 9th European Conference on Antennas and Propagation, EuCAP 2015, Lisbon, Portugal, 13-17 May 2015. - 9788890701856 Konferensbidrag (refereegranskat)abstract Rich Isotropic Multipath (RIMP) environment likereverberation chamber (RC) has proven to be useful forcharacterizing mobile LTE devices. The user statistics have larger effect in environments with stronger Line-Of-Sight (LOS), because the angle of arrival (AoA) and the polarization of the LOS contribution become randomized due to the user. Thus, we introduce the term Random-LOS. The present paper elaborates on characterization of an example antenna in both RIMP and random-LOS. We show how to characterize the micro BTS by the probability of detection (PoD) of one and more bitstreams in both RIMP and random-LOS, by considering the user randomly located and oriented within the angular coverage sector. We limit the treatment to a wall-mounted BTS antenna, and assume a desired hemi-spherical coverage.
26.	Kildal, Per-Simon, 1951, et al. (författare) OTA Testing of 3G-5G Devices with MIMO: From Anechoic Chambers to Reverberation Chambers and ... Back Again? 2017 Ingår i: IEEE Antennas and Propagation Society International Symposium. - 1522-3965. - 9781538632840 ; 2017-January, s. 1697-1698 Konferensbidrag (refereegranskat)abstract The present paper describes the paradigm shift in OTA testing that came with the arrival of the 4G wireless system. The testing was previously mainly done in anechoic Line-Of-Sight (LOS) environments, and now in 4G it is done in reverberation chambers, emulating Rich Isotropic MultiPath (RIMP). Now we are preparing for the 5G wireless system, which is expected to have mm-wave antennas with steerable lobes. This will require OTA testing in anechoic environments again, but with an emphasis on system measurements, i.e. data rate throughput for an arbitrary location and orientation of the user, referred to as Random-LOS.
27.	Lehne, Per H., et al. (författare) Analyzing smart phones' 3D accelerometer measurements to identify typical usage positions in voice mode 2016 Ingår i: 10th European Conference on Antennas and Propagation, EuCAP 2016; Davos; Switzerland; 10 April 2016 through 15 April 2016. - 2164-3342. - 9788890701863 ; , s. Art. no. 7481895- Konferensbidrag (refereegranskat)abstract Smart phone sensors provide new possibilities to understand how devices are actually used and handled in real-life situations. Such information can possibly be used to design better handsets, but also to improve network performance. For example, the radiated performance of a wireless device depends on its orientation and position relative to the user. Hence, knowing realistic handset usage plays a major role in the Over-The-Air characterization of antennas and wireless devices in general. This paper presents an analysis of usage positions for voice service. A simplified statistical model based on data collected from devices acceleration sensors is presented. The analysis shows interesting results from which we can identify some typical ways the user is handling the phone when in a voice conversation. Our analysis shows clear differences of the orientation of the handset when used with a handsfree set and when not.
28.	Lehne, Per Hjalmar, et al. (författare) Finding the distribution of users in a cell from smart phone based measurements 2016 Ingår i: Proceedings of the International Symposium on Wireless Communication Systems. - 2154-0217 .- 2154-0225. - 9781509020614 ; , s. 538-542 Konferensbidrag (refereegranskat)abstract Mobile users are assumed to be positioned within the cell or sector boundaries of the serving cell in the network. Measurements of location done by the smart phones combined with the network layout show differently. There is a significant amount of users which are actually outside the nominal sector boundaries. Knowledge about the statistical location distribution of users inside or outside the serving cell intended coverage may prove valuable in finding more optimal resource management methods. Another application is the development of over-the-air characterization of base station antennas. Distance and directional statistics are shown for samples of relative positions within the cell sectors of a real network using smart phone based measurements. Samples for LTE in 800 and 1800 MHz non-voice usage and 3G at 2100 MHz voice usage is included. The distance distributions show clearly that the usage density rapidly decrease with the distance, and there is a clear confirmation that lower frequencies have longer range, also in terms of usage density. Mean usage distance for 800 MHz is 1.62 km, while for 2100 MHz it is only 580 m. It also shows that 90% of the usage is within 3.47 and 1.35 km for the two cases, respectively. The directional distributions relative to the sector centre direction shows that 80% of the users are within 153 degrees for lowest frequency, and 109 degrees for the highest.
29.	Lehne, Per Hjalmar, et al. (författare) Measuring user-induced-randomness to evaluate smart phone performance in real envi-ronments 2015 Ingår i: 9th European Conference on Antennas and Propagation, EuCAP 2015, Lisbon, Portugal, 13-17 May 2015. - 9788890701856 Konferensbidrag (refereegranskat)abstract The radiated performance of a wireless device depends on its orientation and position relative to the user. In addition, the antenna performance is different on different devices and it depends on the device model. Hence, to understand the impact of the users behaviour on the device antenna and the resulting network performance an investigation of the device usage and signal quality is of high importance. This paper presents a first analysis of the orientation usage of wireless devices based on data gathered from 5 smart phones over a period of more than two months. The data was obtained from the built-in sensors in the phone, and includes angles of orientation, information about signal quality and the connected network Some interesting trends regarding typical orientations of the phone are presented for both voice and data services. We believe that data of this type has the potential to be used for optimizing the device and the network performance, e.g., when the data is correlated with the experienced channel quality.
30.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) A planar dual-polarized ultra-wideband millimeter-wave array antenna 2018 Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741 Konferensbidrag (refereegranskat)abstract We present a dual-polarized ultra-wideband element in an infinite large array condition for planar phased array antennas in mm-wave applications. The array antenna consists of tightly-coupled bowties in a dual-offset configuration. In order to simplify the manufacturing process and eliminate the scalability limitation, a new feeding network is employed. The feeding is inspired by magneto-electric dipoles (MEDs) and planar ultra-wideband array antennas (PUMAs). Hence, the feeding is integrated with the horizontally oriented radiating bowties and removes the need for the external baluns. The simulated antenna shows relative bandwidths of 2.3 : 1 and 3 : 1 at VSWR<3, for maximum scanning angles of 60° and 45°, respectively, at both E- and H-planes.
31.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) A Planar Single-Polarized Ultra-Wideband Antenna Element for Millimeter-Wave Phased Array 2018 Ingår i: 2018 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP). - 9788957083048 ; , s. 797-798 Konferensbidrag (refereegranskat)abstract We propose a single-polarized ultra-wideband element for mm-wave phased arrays. The element is comprised of tightly-coupled bowties fed by a specific configuration of plated via holes. The corresponding feeding network is implemented in such a way to eliminate the use of an external balun. In addition, it provides the possibility to be manufactured by PCB technology. The simulated element has a relative bandwidth of 2.56:1 at a reflection coefficient better than 8 dB while scanning up to 45 degrees. The reflection coefficient remains below 6 dB for a maximum scanning angle of 60 degrees.
32.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) A self-grounded dual-polarized wideband bowtie with improved MIMO performance in Random-LOS 2016 Ingår i: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016 - Proceedings. - 9781509028863 ; , s. 531-532 Konferensbidrag (refereegranskat)abstract We present a new improved design of the self-grounded dual-polarized wideband bowtie antenna for MIMO application. The antenna is evaluated for the case when the original four ports are combined to two orthogonally polarized ports. The new antenna covers the previous bandwidth but has lower gain and wider beamwidth over the frequency band of interest. The 2×2 MIMO performance of the antenna in Random-Line of Sight (Random-LOS) is evaluated for two bitstreams using the threshold receiver model and Zero-Forcing receiver. The simulated results show an improvement in terms of MIMO multiplexing coverage over a hemisphere for two bitstreams, compared to the previous solution.
33.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Comparison of 2-bitstream polarization-MIMO performance of 2 and 4-port bowtie antennas for LTE in random-LOS 2016 Ingår i: 2015 International Symposium on Antennas and Propagation, ISAP 2015. Konferensbidrag (refereegranskat)abstract We evaluate the performance of a dual-polarized wideband antenna in terms of polarization-MIMO in Random-LOS for two different modes of operation: 2 and 4-port excited mode. The 2-port mode was obtained by differential excitation of two opposite ports of the 4-port design by using two baluns. The Zero-Forcing receiver throughput is evaluated based on the Probability of Detection of two bitstreams when orthogonal polarizations provide the MIMO subchannels. Assuming a uniform distribution for the Angle of Arrivals and orthogonally polarized waves incident on the antennas, the overall PoD over coverage cones of 30°, 60° and 90° are presented. The 2-bitstream multiplexing MIMO efficiency defined at the 95% Probability of Detection is evaluated for the two modes of operation at different frequencies and for different coverage cones. The 2-bitstream coverage pattern of the antenna for the two modes are plotted over the range of Angles-of-Arrival (AoA), by choosing fixed polarization (horizontal and vertical) for the incoming waves. The coverage pattern is significantly degraded for the 2-port mode, in particular in the middle of the band. © 2015 The Institute of Electronics, Information and Comm.
34.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Designing a dual-polarized octave bandwidth bowtie antenna for a linear array 2016 Ingår i: 2016 10th European Conference on Antennas and Propagation, EuCAP 2016. - 9788890701863 ; , s. Art. no. 7481892- Konferensbidrag (refereegranskat)abstract In this paper, we propose a linear array configuration for Random Line-of-Sight Over-The-Air testing set-up in anechoic chamber. For this aim, we use the self-grounded dual-polarized bowtie antenna as the element in the array. We present a new design of the bowtie to improve the array performance in terms of reflection coefficient and directivity. The new design has a simpler profile to manufacture. A good reflection coefficient performance has been achieved over the entire band of interest, i.e., 1.6-3GHz. The directivity of the array is almost constant for both polarizations over the entire frequency band.
35.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Double broadband balun structure using CRLH TL for differential excitation of dual-polarized self-grounded bow-tie antenna 2015 Ingår i: Progress in Electromagnetics Research Symposium. - 1559-9450 .- 1931-7360. ; 2015-January:2015, s. 1966-1970 Konferensbidrag (refereegranskat)abstract A broadband compact balun comprising two composite right-left handed transmission lines (CRLH TL) is designed to excite a self-grounded bow-tie antenna. The design is based on a fractal shaped CRLH TL balun modified to the frequency band of interest. This balun consists of one +90° branch and three-90° branches to produce the desired 180° phase difference at the output. The simulated results show an amplitude imbalance of less than 1dB and a phase imbalance of less than 10°over most of the target bandwidth, i.e., 1.6-3 GHz. Two of the designed baluns were integrated with the bow-tie antenna in such a way that the feeding network could totally fit at the back of the antenna. The performance of the whole structure was also evaluated showing a return loss below-10 dB. The radiation pattern and the gain of the antenna with baluns are in good agreement with the ideal differential excitation, with gain degradation of only about 0.5 dB in the worst case.
36.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Improvement of an octave bandwidth bowtie antenna design based on the analysis of a MIMO efficiency metric in random-LOS 2017 Ingår i: Microwave and Optical Technology Letters. - : Wiley. - 1098-2760 .- 0895-2477. ; 59:6, s. 1229-1233 Tidskriftsartikel (refereegranskat)abstract A multiple-input multiple-output (MIMO) efficiency metric based on the probability of detection (PoD) of data bitstreams is used to improve the design of a self-grounded dual-polarized wideband bowtie antenna over an octave bandwidth. The analysis is based on the ideal digital threshold receiver model for the Zero-Forcing algorithm. The random line-of-sight (Random-LOS) channel model with two orthogonal linearly polarized waves coming from the same angle-of-arrival is considered in the evaluation. The MIMO efficiency performance is presented along with the reflection coefficient, the directivity and the radiation patterns of the antennas. Corresponding spatial throughput coverage patterns based on 2-bitstream MIMO efficiency evaluated at the 95% PoD level are also provided. The loss of orthogonality as well as the power imbalance of the 2-bitstreams has been identified as the main reasons to MIMO efficiency performance degradation in Random-LOS.
37.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Semi-omnidirectional dual-polarized wideband multiport antennas for MIMO applications in Random-LOS and RIMP 2017 Ingår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017. - 9788890701870 ; , s. 636-639 Konferensbidrag (refereegranskat)abstract We present two configurations of multiport antennas for Multiple-input Multiple-output (MIMO) application. The configurations are comprised of three and four dual-polarized self-grounded bowtie antenna as the element, respectively. The MIMO performance of both antennas is evaluated in Random Line-of-Sight (Random-LOS) and Rich Isotropic Multipath (RIMP) channel models as two edge propagation environments. Both configurations provide 360° azimuth and 120° elevation angular coverage in Random-LOS and full sphere coverage in RIMP. Using digital threshold receiver model and Zero-Forcing receiver, the performances of both configurations are evaluated in terms of Probability of Detection (PoD) and MIMO multiplexing efficiency calculated at 95% PoD level. The simulated results show a good performance for both structures in two edge environments, which can be concluded as a good performance in a real life situation.
38.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Ultra-Wideband Millimeter-Wave Bowtie Antenna 2017 Ingår i: 2017 International Symposium on Antennas and Propagation. - 9781538604656 ; 2017-January Konferensbidrag (refereegranskat)abstract We present an ultra-wideband antenna for mm-wave applications. The antenna consists of a bowtie patch integrated with the feeding network. The feeding network is implemented as a multilayer substrate structure. The differential excitation of the bowtie is performed in a similar way to Magneto-Electric Dipoles and Marchand baluns. The simulated antenna shows a relative bandwidth of 2.6 : 1 with a reflection coefficient better than -8 dB. The radiation pattern remains fairly stable over 20 - 50 GHz with a boresight directivity of 5:8 - 8:3 dBi.
39.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Ultrawide Band Tightly-Coupled Aperture Magneto-Electric Dipole Array over 20 - 40 GHz 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. Konferensbidrag (refereegranskat)abstract We propose a linearly-polarized wideband phased-array for millimeter-wave applications. The array is composed of tightly-coupled Magneto-Electric Dipoles fed by slot-coupled microstrip lines. The integration of the radiating elements with the feed structure removes the need of an external balun and simplifies the manufacturing process. The simulated antenna provides 64% bandwidth at VSWR < 2 and 60% bandwidth at VSWR < 2.65 for scanning up to 45 and 60 in both E- and H-planes, respectively.
40.	Mansouri Moghaddam, Sadegh, 1987, et al. (författare) Wideband Dual-Polarized Linear Array Antenna for Random-LOS OTA Measurement 2018 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 66:5, s. 2365-2373 Tidskriftsartikel (refereegranskat)abstract In this paper, an 8×1 dual-polarized linear array antenna is proposed for a random line-of-sight over-the-air measurement system. The proposed array antenna operates over the frequency band of 1.6-2.7 GHz. A self-grounded bowtie is optimized as the array element. A compact wideband two-port feeding network is designed and manufactured to differentially excite each element, while each port excites one of the two orthogonal polarizations. Corrugated plates have been employed in the transverse plane of the linear array in order to achieve the same beamwidth for both polarizations over the entire band. A prototype has been manufactured and the measured reflection coefficient is better than -10 dB. The realized gain and the half-power beamwidth of the array in the transverse plane of the array remain fairly constant over the entire band of interest.
41.	Miao, Yang, et al. (författare) Comparing Channel Emulation Algorithms by Using Plane Waves and Spherical Vector Waves in Multiprobe Anechoic Chamber Setups 2019 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:6, s. 4091-4103 Tidskriftsartikel (refereegranskat)abstract This paper evaluates the performances of channel emulation algorithms in the multiprobe anechoic chamber (MPAC) by using plane wave (PW) and spherical vector wave (SVW) theories. Channel emulation in MPAC enables the over-the-air (OTA) testing of performances of wireless devices under realistic propagation scenarios, through setting excitation voltages of probes and utilizing the polarized radiation patterns, locations, and orientations of probe antennas to emulate desired fields in test zone. Accurate emulation of radio wave propagation in target scenario guarantees that the device under test (DUT) be assessed fairly in the laboratory. Dynamic multipath scenario and orthogonal polarization can be emulated by exciting the multiple probes in such a way that the total fields from probes resemble the target impinging field in the test zone. The excitation voltages can be either calculated by PWor SVW theories. Despite the fact that PW and SVW are mathematically equal in the far field, different treatments on rotation and translation of waves as well as different linear equations used in two methods result in different computed voltages, hence, different emulated fields. The emulation performances of the two methods with different MPAC setups (e.g., test zone size, probe number, probe sphere radius, and probe directivity) are investigated. Both scenarios of the 2-D field emulation with the 2-D probe configuration and the 3-D (or 2.5-D) field emulation with the 3-D probe configuration are discussed, and instructions on how to wisely use the emulation algorithm are provided.
42.	Miao, Yang, et al. (författare) Comparison of Plane Wave and Spherical Vector Wave Channel Modeling for Characterizing Non-Specular Rough-Surface Wave Scattering 2018 Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 17:10, s. 1847-1851 Tidskriftsartikel (refereegranskat)abstract This letter demonstrates advantages of modeling the nonspecular wave scattering from surfaces of a multiple-input multiple-output (MIMO) channel in terms of the spherical vector wave (SVW) mode expansion. We propose the SVW mode coupling matrix M as a more efficient alternative to the commonly used set of distinct plane waves. M incorporates the scattered field components through the limited number of modes due to the cutoff property. A planar surface with random roughness is used to simulate the nonspecular scattering contribution to the radio channel, which is computed using physical optics. The matrix M and the plane wave channel model parameters are estimated from simulated radio channels. The estimates are used to compare the contribution of the nonspecular scattering to the radio channel reproduced from these two approaches. The comparison is performed for a small array antenna arrangement. Compared are the error of themagnitudes of MIMO channel transfer matrix, the narrowband channel eigenvalues, the correlation matrix distance, and the mutual information. It is found that M from the SVW channel modeling performs better in reproducing the radio channel of nonspecular scattering from the studied rough surface.
43.	Miao, Yang, et al. (författare) Investigating Correlation of Rough Surface Diffuse Scattering in Frequency Domain 2019 Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. - 9788890701887 Konferensbidrag (refereegranskat)abstract This paper investigates numerically the correlation function in the frequency domain due to diffuse scattering originated from rough surfaces. The scattered fields are computed by means of physical optics methods. The irregularities of the rough surface are modeled as a correlated Gaussian process. The correlation of the channel transfer function comprising only diffuse scattering components is analyzed. In the analysis, radio propagation channels comprising orthogonally oriented dipoles at the link ends are considered while assuming different Gaussian roughness profiles. This study offers a useful characterization of the channel behavior in a multipath-rich environment due to diffuse scattering. The presented results are of particular interest to wireless systems based on orthogonal frequency-division multiplexing.
44.	Oakes, Benjamin Donald, et al. (författare) A Systems-Based Risk Assessment Framework for Intentional Electromagnetic Interference (IEMI) on Critical Infrastructures 2018 Ingår i: Risk Analysis. - : Wiley. - 0272-4332 .- 1539-6924. ; 38:6, s. 1279-1305 Tidskriftsartikel (refereegranskat)abstract Modern infrastructures are becoming increasingly dependent on electronic systems, leaving them more vulnerable to electrical surges or electromagnetic interference. Electromagnetic disturbances appear in nature, e.g., lightning and solar wind; however, they may also be generated by man-made technology to maliciously damage or disturb electronic equipment. This article presents a systematic risk assessment framework for identifying possible, consequential, and plausible intentional electromagnetic interference (IEMI) attacks on an arbitrary distribution network infrastructure. In the absence of available data on IEMI occurrences, we find that a systems-based risk assessment is more useful than a probabilistic approach. We therefore modify the often applied definition of risk, i.e., a set of triplets containing scenario, probability, and consequence, to a set of quadruplets: scenario, resource requirements, plausibility, and consequence. Probability is replaced by resource requirements and plausibility, where the former is the minimum amount and type of equipment necessary to successfully carry out an attack scenario and the latter is a subjective assessment of the extent of the existence of attackers who possess the motivation, knowledge, and resources necessary to carry out the scenario. We apply the concept of intrusion areas and classify electromagnetic source technology according to key attributes. Worst-case scenarios are identified for different quantities of attacker resources. The most plausible and consequential of these are deemed the most important scenarios and should provide useful decision support in a countermeasures effort. Finally, an example of the proposed risk assessment framework, based on notional data, is provided on a hypothetical water distribution network.
45.	Poordaraee, Mohammad, et al. (författare) Plane Wave Synthesis with Irregular Chamber Planar Antenna Arrays for Compact OTA Measurements 2019 Ingår i: 2019 13TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). - 2164-3342. - 9788890701887 Konferensbidrag (refereegranskat)abstract Over-The-Air (OTA) testing techniques shall meet cost- and time-efficiency as well as measurement accuracy constraints stemming from the characterization of massive multi-element array antennas in 5G systems. The Random-LOS (Line-of-Sight) OTA measurement setup aims at emulating a plane wave field in the test zone of the measurement chamber. The test zone is in the near-field of the chamber antenna used to emulate the far-field from a base station. In this paper, the thinned array antenna concept is applied to synthesize the plane wave field within the test zone. The thinning is performed by means of the Genetic Algorithm. Two planar array antenna configurations are considered for emulating a plane wave for 2D and 3D test zones at 2.7 GHz. The optimized thinned array achieves a 55% reduction of the number of antenna elements. In addition, amplitude and phase fluctuations in the test zone have been considerably reduced in comparison to other similar array antennas, in this way, improving the measurement accuracy in Random-LOS OTA measurement setups.
46.	Prinsloo, D.S., et al. (författare) Characterization and Performance of an Ultra-Wideband Wide-Coverage Multimode MIMO Antenna 2019 Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 67:9, s. 5812-5823 Tidskriftsartikel (refereegranskat)abstract A new ultra-wideband multimode (MM) antenna design that enables the detection/transmission of two orthogonal field components over a nearly hemispherical coverage area is presented in this paper. It integrates and colocates two perpendicularly oriented bow-tie dipole elements, a short convex monopole and four horizontally oriented tapered slot antenna (TSA) elements (formed by the dipoles) in order to produce four decoupled and complementary gain patterns. The antenna feeding structure includes four single-ended transmission lines supporting the desired set of individual excitation modes. Experimental verification confirms the predicted negligible coupling between the antenna operating modes and orthogonality of the corresponding radiated field patterns. These unique features can be exploited in applications where pattern and polarization diversity are of importance. In this study, we have evaluated the proposed antenna as a MIMO base station antenna and characterized it in two different propagation scenarios. For this example, it has been shown that the utilization of the additional monopole and TSA modes plays an important role in maximizing MIMO efficiency in line-of-sight (LOS) scenarios and at the same time provides additional independent data streams in rich scattering scenarios. In both considered scenarios, the antenna is shown to have a MIMO frequency bandwidth of 85%.
47.	Prinsloo, D.S, et al. (författare) Synergy in design of phased array antennas for modern radio astronomy and wireless communication systems 2016 Ingår i: 10th European Conference on Antennas and Propagation, EuCAP 2016, Davos, Switzerland, 10-15 April 2016. - 2164-3342. - 9788890701863 Konferensbidrag (refereegranskat)abstract This paper accentuates the similarity in the requirements of the radiation characteristics of antenna elements used in directive beam-steering arrays for radio astronomy and wireless communication systems, i.e. aperture phased array radio telescopes and base transceiver stations. Using two reference antenna elements the equivalence between two beamforming strategies commonly implemented in wireless communication and radio astronomy systems is illustrated. For the case of maximum power receivers it is demonstrated that the methodology followed to assess and characterize the performance of an antenna element in wireless communication systems can readily be implemented to compare the field-of-view (FoV) coverage of antenna elements in radio astronomy applications. Finally, using an ideal reference element, it is shown that a single figure-of-merit - field-of-view coverage gain - can be used to compare the performance of antenna elements over an entire field-of-view coverage.
48.	Razavi, Aidin, 1982, et al. (författare) Array-fed cylindrical reflector antenna for automotive OTA tests in Random Line-Of-Sight 2016 Ingår i: 2016 10th European Conference on Antennas and Propagation, EuCAP 2016. - 9788890701863 ; , s. 7481689- Konferensbidrag (refereegranskat)abstract In this paper we look into a near-field measurement setup consisting of a cylindrical reflector and a linear array feed. The main application is Random Line-Of-Sight Over-The- Air measurements in anechoic or semi-anechoic chambers (i.e., anechoic chamber with reflecting floor). More specifically, the aim is testing the wireless communication systems on automotive vehicles. The aim is to generate the uniform field distribution of a plane wave over a pre-defined test zone containing the car or at least the part of the car containing the antenna(s). The field intensity variations over the testing zone have been investigated for reference measurements over the testing frequency bandwidth, i.e., 1.6-2.8 GHz. © 2016 European Association of Antennas and Propagation.
49.	Razavi, Aidin, 1982, et al. (författare) Characterization method of an automotive random-LOS OTA measurement setup 2018 Ingår i: Progress In Electromagnetics Research C. - 1937-8718. ; 84, s. 47-60 Tidskriftsartikel (refereegranskat)abstract A novel characterization method of OTA test setups for wireless communication systems on vehicles in the random line-of-sight (Random-LOS) environment is proposed. The measurement setup assumes a compact range and a test zone where the antenna under test (AUT) on the vehicle would be located. An ideal receiver is assumed for the reference measurement, which allows to perform a system analysis through evaluating the Probability of Detection (PoD) as the system figure-of-merit. The proposed method is aimed as an aid for test equipment designers to design OTA compact ranges, compare their performances, and define an ideal numerical reference. The requirements for OTA measurement ranges are different from those for conventional anechoic compact ranges. A compact cylindrical reflector system with an antenna array line feed is characterized using the proposed method, from 1.6-2.7GHz, for two orthogonal polarizations, various AUT heights and reflector tilting angles, with and without ground plane in a test zone which is 2m wide in diameter.
50.	Razavi, Aidin, 1982, et al. (författare) Characterizing Polarization-MIMO Antennas in Random-LOS Propagation Channels 2016 Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 4, s. 10067 - 10075 Tidskriftsartikel (refereegranskat)abstract In the 5G system, we foresee the use of LOS-dominated mm-wave radio links to moving users being subject to slow fading resulting from the users’ random locations and orientations. We refer to this as a random-LOS channel. MIMO processing algorithms will be used in 5G to improve performance in slow fading, similar to how they are used in Rayleigh fading. To this end, we study the probability of detection in the random-LOS channel when there are dual-polarized antennas on both sides of the link. We introduce two polarization deficiencies: the polarization non-orthogonality and the amplitude imbalance between the ports of a two-port antenna. The MIMO efficiency is evaluated as a function of these deficiencies. In the analysis, we consider the MRC algorithm for one bitstream, and the ZF and SVD algorithms for two bitstreams. We also present two analytical formulas for the MIMO efficiency that can be used to determine performance. We use the formulas on two ideally orthogonal dipoles, and show by means of coverage plots how much the 1- and 2-bitstream performances degrade due to the polarization deficiencies in off-boresight directions.

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