Measured multi-user MIMO capacity in Aircraft

Journal ArticleThe multipath richness typical of aircraft channels represents a potentially well-suited environment for multi-user multiple-input multiple-output technology (MU-MIMO). This paper presents results from measurements of the achievable MU-MIMO data rates in a Rockwell T-39 Sabreliner, using an open-source software-defined radio (SDR) test bed. We also compared the achievable capacity of dirty-paper coding (DPC) against time-division multiple access (TDMA) to illustrate the value of advanced MU-MIMO techniques in aircraft environments. Measured data was then compared against values obtained from a three-dimensional ray-tracing simulation. For transmitters located near the ends of the aircraft, the average error between simulated and measured capacity was on the order of 2% or less. For the more-centralized transmitter location, simulations predicted an average of 6% less capacity than what was actually measured

Challenges with optically transparent patch antennas

pre-printIn this paper, antennas made out of transparent conducting oxides (TCOs) are explored. The optical transparency of transparent conducting oxides is achieved through thin-film depositions on substrates. However, thin-film depositions create a new set of electrical challenges that require a full understanding of semiconductor physics. This work looks into the governing equations that limit light transmission, absorption, and reflection through a transparent conductor, along with the electrical conductivity and antenna efficiency of transparent-conducting-oxide thin-film patch antennas

System level analysis of noise and interference analysis for a MIMO system

Journal ArticleMultiple input multiple output antenna communication system are gaining importance in the field of communication and ad-hoc networks due to increase demand for wireless throughput in band-limited channels. A system analysis is not complete without accounting for the system level noise and interference. This abstract provides a simple system level model including noise and interference to enable detailed analysis of MIMO system. Multiple-input-multiple-output systems have been studied for more than a decade, since Froschini's landmark conclusion that the theoretical information capacity increases linearly with the number of antennas for rich multipath channels [1]. Experimental characterization and model development have shown that the ideal linear capacity increase is not achievable in practice due to a number of factors including correlation of the communication channel, close antenna spacing and subsequent mutual coupling [2-4]. The capacity also depends on the type of channel state information (CSI) available. A popular expression for MIMO capacity is: [3

Iterative array level optimization of MIMO antennas

Journal ArticleMultiple-input-multiple-output systems have gained importance in the last decade due to their ability to provide improved capacity as compared to their SISO counterparts. System optimization promises further improvement in the capacity. The optimization can be either optimization of detection algorithms or optimizing the hardware designs. Starting with the network level MIMO model which includes the affect of mutual coupling and antenna correlation and an extended MIMO transmission model considering polarization, antenna efficiency, radiation pattern for capacity we analyze some simple antenna configurations for MIMO. This paper analyses the affect of each of the parameters on capacity obtained by using single dipole and three PIFA antenna configurations. Further antenna optimization for capacity including noise and interference will be presented at the conference

Measurement and modeling of multiuser multiantenna system in aircraft in the presence of electromagnetic noise and interference

ManuscriptThis paper evaluates the accuracy with which the performance of a multi-user multi-antenna system can be predicted with and without considering co-channel interference and noise (Gaussian, α- stable and Cauchy) using a site-specific 3D ray-tracing algorithm as well as with statistical models with Gaussian and Nakagami-m channel models in small to medium sized aircraft. These models expand on previous statistical channel models such as the hyper-Rayleigh model by including the simultaneous effects of co- and adjacent channel interference, antenna matching, efficiency, directivity and polarization as well as (for the 3D model) site-specific multipath effects. Measurements and comparisons are made in a metallic-bodied Beech Baron BE 58P and a composite structure Rockwell T-39 Sabreliner. It was found that the 3D ray tracing model provides a mean capacity within 1 % of those measured in the two aircraft in the presence of interference and noise. This was closely followed by the Nakagami-m distribution (m=1.4) which was within 1-3% of measured capacity in the presence of interference and within 6% for a combination of interference and noise and the Gaussian model which was within 6% of measured capacity in the presence of interference and within 11% for a combination of interference and noise . The Cauchy noise degraded the capacity more than the other types of noise in the aircraft, providing a lower bound for capacity in an aircraft system

Enabling wireless communication in aircraft using multipe antenna systems

Journal ArticleSensor technology is advancing to provide the robust, miniaturized sensors needed for aircraft prognostics health management (PHM). Aircraft maintainers would like to add numerous pressure, temperature, vibration, fuel quantity, moisture/chemical sensors, but a major challenge of retrofitting old aircraft with them is how to collect the data. Wireless data transfer in aircraft has been identified as a 'transformative' technology for aviation. The industry is pursuing wireless prospects, but so far all are limited by the extreme multipath channels in aircraft. Spread spectrum communication is extremely limited in aircraft because of the multipath channels[l], and [2] found problems with ultrawideband interfering with aircraft radios, even when operated at approved, 'safe' levels. This paper explores multiple input multiple output (MIMO) communication in aircraft because of its high capacity in rich multipath environments. In addition to the multipath that raises MIMO capacity, the aircraft channel is also rich in noise, interference, and channel correlation that decreases its capacity. This paper presents a complete channel model for MIMO in aircraft that includes the effects of noise, interference and channel correlation. The capacity obtained from this detailed system model is used as a metric for antenna selection and system evaluation

Antenna optimization for vehicular environments

Journal ArticleAbstract? This paper presents a multi-antenna optimization for communication in a Rockwell T-39 Sabreliner, a mid-size aircraft with a metallic body. The aircraft channel at 2.45 GHz is modeled using site specific 3D ray-tracing software. Added effects from system details including the antenna radiation patterns, mutual coupling, etc. are incorporated into a network theory based detailed signal model. The paper considers traditional antennas including dipoles, square patches, PIFAs, and polarization agile patches along with some more complex shaped patches and PIFAs. A random search algorithm was used to optimize capacity for arrays with widely divergent element count, element type, matching, directivity, polarization alignment, efficiency, spatial correlation and coupling. The polarization agile patch provides the best capacity for locations near the aircraft ceiling while the PIFAs with more variety in shape (spiral shapes) provide the best capacity for locations near the floor. This is because the signals reaching the roof and sides contain more polarization diversity than those in the center of the body where the nonconductive floor is located

Pressure-dependent inverse bicontinuous cubic phase formation in a phosphatidylinositol 4-phosphate/phosphatidylcholine system

In this paper, we report the inositide-driven formation of an inverse bicontinuous cubic phase with space group Ia3d (QIIG, gyroid phase). The system under study consisted of distearoylphosphatidylinositol 4-phosphate (DSPIP) and dioleoylphosphatidylcholine at a molar ratio of 1:49, with a physiological concentration of magnesium ions at pH 7·4. The behaviour of the system was monitored as a function of temperature and pressure. The formation of the phase with Ia3d geometry was recorded repeatably at high pressure, and occurred more readily at higher temperatures. We conclude that the Ia3d phase formed is a thermodynamically stable structure, and that DSPIP is a potent source of membrane curvature that can drive the formation of mesophases with both 2- and 3D geometry