Rician Factor Research Articles

English

This paper analyzes the power ratio between the directed line of sight configuration links increased by reducing the receiver Field of View (FOV). Line of Sight systems employ high degree of directionality of the transmitter and receiver and uninterrupted LOS. LOS link design reduces multipath distortion and increases power efficiency. The performance of the link relies upon the existence of an uninterrupted LOS path between the transmitter and receiver. This can be quantified by the Rician factor. The Field of View of the receiver is related to the collection area of a lens and the photo detector area. The FOV of the detector is smaller than the radiation incident angle. It is an observation that the concentrator gain or channel gain increases when the value of FOV reduces. In this paper, the line of sight channel gain is calculated at different values of FOV.

Analysis of envelope correlation on performance of MRC in correlated Rician-fading channels

A simple envelope correlation expression of two maximal-ratio combined (MRC) signals in correlated diversity Rician-fading channels is derived in high signal-to-noise ratios (SNRs). In addition, the relationship between the system performance and envelope correlation is also obtained, which indicates that it is much easier to evaluate the system performance using the envelope correlation, since the effects of parameters such as the Rician factor and all channel attenuations are able to be replaced by the envelope correlation. The validity of the analytical relationship is verified by numerical simulations using a correlated Rician-fading emulator.

Performance Analysis of Hybrid Cooperation in Asymmetric Fading Channels

In this paper, symbol-error-rate (SER) performance analysis is provided for hybrid cooperation (HC) system in an asymmetric fading environment where the source-to-relay and the relay-to-destination channels experience independent Rayleigh/Rician and Rician/Rayleigh fading, respectively, while the direct channel link between the source and the destination is subject to Rayleigh fading. Unlike most existing relaying protocols which use amplify-and-forward (AF) or decode- and-forward (DF) protocol separately, the HC system takes advantage of both AF and DF protocols simultaneously. Based on the theoretical analysis, analytical expressions for the moment generating function (MGF) of the end-to-end signal-to-noise ratio (SNR) are derived and used to evaluate the SER performance of the HC system with M -ary phase shift keying ( M -PSK) modulation. Numerical and simulation results are presented to verify the theoretical analysis, where we also illustrate the impact of the Rician factors on system performance.

Comparisons of Channel Parameters and Models for Urban Microcells at 2 GHz and 5 GHz [Wireless Corner

The goal of this paper was to find the differences of the channel models and parameters as well as the correlations of the channel parameters between 2 GHz and 5 GHz with 100 MHz bandwidth when measurements were performed in exactly the same routes for urban microcells. The path-loss models and shadow fading were studied by using single-input single-output (SISO) measurements. The channel characteristics were investigated by the rms delay spread, rms angular spread, shadow fading, Ricean factor, number of clusters, cross-polar discrimination, and channel capacities using both SISO and MIMO (multiple-input multiple-output) measurements. Static measurements at 5 GHz were also performed in both micro- and macro-cells to investigate clustering effects. Moreover, the channel models and parameters were compared with WINNER work to test their validity in urban microcells. The main conclusion was that the 2 GHz and 5 GHz frequencies can have different propagation behaviors causing the independent channel parameters. However, it was found that their coherence bandwidths were highly correlated. The WINNER path-loss models over-estimate the path losses, both in the line-of-sight (LOS) and non-line-of-sight (NLOS) street canyons where strong guided waves exist. Irrespective of carrier frequencies, the channel parameters offered by WINNER may roughly estimate the channel by implementing its generic model.

The Channel Capacity of Dual-Polarized MIMO Mobile Satellite System

Applying Multiple-Input Multiple-Output (MIMO) technology in terrestrial wireless networks can obtain large capacity gain. Therefore, MIMO technology is widely applied in satellite communication system, in which orbital positions are increasingly crowded and frequency resources are of shortage. This paper attempts to research on channel capacity in 2×2 dual-polarized MIMO mobile satellite (DMMS) system and discovers that when XPD (Cross Polarization Discrimination) is above zero, the channel capacity increases approximately linearly with the XPD within certain range. Adding Ricean factor K in consideration of its special features,the system’s capacity increases with the Ricean factor K. Simulation results demonstrate that the application of MIMO technology in satellite mobile communication system can improve the channel capacity significantly, providing great support for the development of future satellite MIMO technology.

Performance Analysis of RF Self-Interference Cancellation in Full-Duplex Wireless Communications

An expression of radio frequency (RF) interference cancellation ratio (ICR) is derived for full duplex wireless communications, considering the amplitude and phase errors in Rician fading channel. The results show that the amplitude and phase estimation errors of line-of-sight (LOS) components are the significant factors that limited the performance when Rician factor K > 1. ICR 55 dB can be achieved when the standard deviation of LOS component relative amplitude error is less than 0.1% and the standard deviation of LOS component phase error is less than 0.1°.

Differential Maximum Ratio Combining (MRC)-Based Throughput Analysis on Dual-Fading Models of Slotted-Aloha CDMA Systems

In this paper we investigate throughputs of Slotted-ALOHA code division multiple access systems with differential detection upon L-branch antenna by means of maximum ratio combining (MRC) diversity technique. We investigate the effects of co-channel interference by employing two different fading models (i.e. between the desired signals and its interferences.) We consider systems under Nakagami/Nakagami and Rician/Nakagami fading environments. The purpose of employing MRC diversity and differential phase shift keying with L-branch antenna is to overcome multipath fading interference in order to enhance the performance of the systems. Our research indicates that the implementation of L-branch antenna in the receiver have reasonably increased the throughputs of the systems. Furthermore, we also investigate the inverse relation between interference signal and the throughputs of the systems. We further point out that the value of Nakagami fading parameter M and Rician factor K are proportional to the achievable throughputs of the systems.

Performance Analysis of Optimal Beamforming in Fixed-Gain AF MIMO Relaying over Asymmetric Fading Channels

This paper analyzes the performance of an optimal single stream beamforming scheme for a multiple-input multiple-output (MIMO) relay network with dual-hop fixed-gain amplify-and-forward (AF) relaying. The source-relay and relay-destination channels undergo Rayleigh and Rician fading respectively. Different Rician fading scenarios are considered for relay-destination channel, depending on the rank of the Rician channel matrix. The channel state information is only available at the destination, and the destination computes the optimal transmit and receive beamforming vectors to maximize the instantaneous signal-to-noise ratio (SNR). The optimal transmit beamforming vector is sent back to the transmitter via a dedicated feedback link. We derive new analytical expressions for the cumulative distribution function, probability density function, and moments to statistically characterize the properties of the instantaneous SNR. These statistical properties are used to analyze the system performance in terms of the outage probability, average bit error rate, and the ergodic capacity. The performance analysis investigates the effects of the Rician factor, rank of the line-of-sight component, and number of antennas at the nodes on the system performance. The results reveal that the optimal single stream beamforming system provides better performance than an orthogonal space-time block coded based AF MIMO system.

Practical and Simple Wireless Channel Models for Use in Multipolarized Antenna Systems

The next-generation wireless systems are expected to support data rates of more than 100 Mbps in outdoor environments. In order to support such large payloads, a polarized antenna may be employed as one of the candidate technologies. Recently, the third generation partnership standards bodies (3GPP/3GPP2) have defined a cross-polarized channel model in SCM-E for MIMO systems; however, this model is quite complex since it considers a great many channel-related parameters. Furthermore, the SCM-E channel model combines the channel coefficients of all the polarization links into one complex output, making it impossible to exploit the MIMO spatial multiplexing or diversity gains in the case of employing polarized antenna at transmitter and receiver side. In this paper, we present practical and simple 2D and 3D multipolarized multipath channel models, which take into account both the cross-polarization discrimination (XPD) and the Rician factor. After verifying the proposed channel models, the BER and PER performances and throughput using the EGC and MRC combining techniques are evaluated in multipolarized antenna systems.

Nonisotropic Scattering Characteristic in an Alternant Tree-Blocked Viaduct Scenario on High-Speed Railway at 2.35 GHz

This paper presents the nonisotropic scattering characteristic of the mobile radio channel in an alternant tree-blocked viaduct scenario on high-speed railway (HSR) by real field measuring at 2.35 GHz. An angle of arrival (AOA) probability density function (PDF) is proposed for the nonuniform AOA at the mobile caused by stochastically distributed scatterers. Two Von Mises angular distributions with broad applicability are used to represent the line of sight (LOS) component and part of the scattering component in the AOA model. Based on such a PDF statistical characteristics of Ricean factor,κ, and AOA of the scattering component are modeled in LOS and obstructed line of sight (OLOS) cases, respectively. The results may give a meaningful and accurate channel model and could be utilized in HSR viaduct scenario evaluation.

Calculating the probability of error per symbol on the basis of MGF method using Rician fading for MFSK

In this paper is presented how to calculate the probability of error per symbol of M-ary non-coherent frequency modulation (M-ary Frequency Shift Keying, MFSK) over a slow, flat, identically independently distributed Rician fading channels. SEP is calculated by technique with maximal ratio combining diverzity, using the moment generating function. We assume that the information is known on the receiving side of the channel. Probabilities of error per symbol for the modulation technique are plotted for different values of Rician factor K, diverzity order N and modulation order M.

Received Least Squares Beamforming on Ka-band Channel Model of HAP System

The Ka-band channel model ofHigh Altitude Platform (HAP) for high speed train is modeled as a flat and time varying Rician process with 10-25 dB Rician factor. In order to compensate for the time varying fading channel and considering the fact that the Line-of-Sight (LOS) component is dominant, adaptive beamforming with the leastsquares (LS) approach is employed at the receiver. Theoretical analysis of the LS algorithm is performed for very large Rician factor in the high Signal to Noise Ratio (SNR) regime. In particular, the analysis is with respect to the estimated autocorrelation matrix of the received vector and the beamforming weight. It is shown that, the estimated autocorrelation matrix of the received vector resembles the autocorrelation matrix of the array steering response. The presented analysis are then verified by Monte Carlo simulations.

Symbol Error Rate Analysis of M-QAM with Equal Gain Combining Over A Mobile Satellite Channel

Mobile Satellite Communications (MSC) have become an essential part of the world telecommunication infrastructure. However, the systems suffer from multipath propagation effects. In this paper, error analysis of M-ary quadrature amplitude modulation (M-QAM) with Equal Gain Combiner (EGC) over mobile satellite channel was carried out. The satellite channel was modelled as the product of Rayleigh and Ricians. This was then used to develop a system model for the received signal which was simulated and evaluated in terms of Average Symbol Error Rate (ASER) using the exact closed-form expression derived from moment generating function (MGF) and Pade Approximants (PA) theory. The results showed that at 16dB, Rician factor ‘k’=0, ASER obtained are 41.83%, 18.56% and 10.81% for paths ‘L’ = 2, 3, 4 respectively. ASER values reduced as ‘k’ increased. The results are in agreement with the simulation. DOI: http://dx.doi.org/10.11591/ijece.v3i6.4343

Threshold Constraints on Symmetric Key Extraction from Rician Fading Estimates

Symmetric key establishment using reciprocal quantization of channel estimates in wireless Rician fading environments is considered. The quantization bits from channel-phase and channel-amplitude are treated as the output of a random number generator. We determine threshold constraints on the required minimal distance of the legitimate communicating parties from a passive eavesdropper, and determine threshold constraints on maximal key establishing rates. The analysis makes use of widely accepted statistical test suites applied to the generated bit streams along with a lemma we define and prove. For distance analysis, the minimal required distance from the eavesdropper to maintain perfect secrecy during key establishment is derived. For key establishing rates, the maximal rates are derived while ensuring the generated bits streams pass the statistical test suites. The work results in generic and clear threshold requirements on distance and rates as function of the Rician factor and quantization bit for any transmission frequency. Clear thresholds are useful for systems operating in a-priori known or estimated propagation environments. In addition, we address the effect of imperfect channel reciprocity on key agreement. Results show practical systems can operate under reciprocal and secure conditions, and that channel-phase estimates perform better than channel-amplitude estimates.

Physical Layer Security in MIMO OSTBC Line-of-Sight Wiretap Channels with Arbitrary Transmit/Receive Antenna Correlation

In this paper, the physical layer security of multiple-input multiple-output (MIMO) wiretap channels with orthogonal space-time block codes (OSTBCs) and arbitrary antenna correlation is investigated. In our analysis, we consider general correlation matrices with arbitrary eigenvalue distributions. Also, in order to study the impact of the line-of-sight condition on the secrecy performance, the main channel is assumed to undergo Rician fading, while the eavesdropper one experiences Rayleigh fading. An easy-to-evaluate, closed-form expression for the secrecy outage probability is derived, from which an asymptotic analysis is carried out. Representative numerical results are plotted and validated through Monte Carlo simulations. Insightful discussions regarding the impact of the multiple antennas, correlation, and Rician factor on the secrecy outage performance are provided.

INVESTIGATION OF CAPACITY GAINS IN MIMO CORRELATED RICIAN FADING CHANNELS SYSTEMS

This paper investigate the effect of Rician fading and correlation on the capacity and diversity of MIMO channels. The use of antenna arrays at both sides of the wireless communication link (MIMO systems) can increase channel capacity provided the propagation medium is rich scattering or Rayleigh fading and the antenna arrays at both sides are uncorrelated. However, the presence of line-of-sight (LOS) component and correlation of real world wireless channels may affect the system performance. Along with that we also investigate power distribution methods for higher capacity gains and effect of CSI at the transmitter on the capacity for range of SNR. Our investigation follows capacity gain as function of number of antennas and signal-to-noise (SNR) power ratio Block and frequency nonselective Rician fading channel is assumed, and the effect of Rician factor (L) and the correlation parameter (ρ) on the capacity and diversity gains of MIMO channels are found. Index.

Performance of cross-layer design for orthogonal space-time block coded MIMO systems with imperfect CSI in Ricean fading channels

A cross-layer design (CLD) scheme for orthogonal space-time block coded MIMO systems with imperfect channel state information is presented by combining adaptive modulation and automatic repeat request, and the corresponding system performance is investigated over Ricean fading channel. The fading gain value is partitioned into a number of regions by which the modulation is adapted in terms of the region the fading gain falls in. The fading gain switching thresholds subject to a target packet error rate (PER) constraint are derived. According to these results, and using the generalized Marcum Q-function, we derive the theoretical formulae of average PER and spectrum efficiency (SE) of the system with CLD for both perfect and imperfect estimation in detail. As a result, closed-form expressions for average PER and SE are obtained. These expressions include some existing expressions in Rayleigh channel as special cases. With these expressions, the system performance in Ricean channel with perfect and imperfect estimation information can be evaluated effectively. Computer simulation for average PER and SE show that the theoretical analysis and simulation are consistent. The results show that the system performance will be effectively improved as Ricean factor increases, but it will be degraded as estimation errors increases.

Variable Rate Space-Time- Block-Code Error Analysis for Ricean Faded Channel for PSK and QAM Signals

The design of wireless systems is open for further improvements in respect of spectrum efficiency, coverage area and link reliability. Multiple-Input-Multiple-Output (MIMO) links are capable to overcome the limitations of data rate and range of wireless devices by exploiting bandwidth efficiency of multiple transmit and receive antennas. Improved efficiency can further be possible by incorporating the Space Time Block Code (STBC) with MIMO system. Researches on MIMO systems with STBC have becoming an important area that improves the performance of system without additional bandwidth or transmit power requirements. This paper presents STBC models in Ricean fading environment using various combinations of transmit and receive antenna numbers. The simulations results have been obtained in MATLAB platform. The bit error rate performance has been analyzed for the Ricean factors of k = 0, 1, and 10 in both the BPSK and 16 QAM modulation schemes.

Noncoherent Amplify-and-Forward MIMO Relaying With OSTBC Over Rayleigh–Rician Fading Channels

This paper investigates orthogonal space-time block-coded (OSTBC) transmission for a multiple-input multiple-output (MIMO) channel with noncoherent amplify-and-forward (AF) relaying in a situation where the source–relay and relay–destination channels undergo Rayleigh fading and Rician fading, respectively. Fading coefficients of the Rician channel are considered to be correlated. Different scenarios are then considered for the Rician channel. We derive exact expressions for the moment-generating function (mgf) and the first and second moments of the instantaneous signal-to-noise ratio (SNR) at the destination to statistically characterize system behavior. We also derive the exact expressions for the probability density function (pdf) and the cumulative distributive function (cdf) to discuss system behavior with the Rician factor. We then analyze system performance by deriving new analytical expressions for the bit error rate (BER), outage probability, amount of fading (AoF), diversity order, and array gain. These performance metrics reveal that strong line-of-sight (LoS) components between a relay–destination link always limit the performance promised by the MIMO scattering environment when both nodes have multiple antennas.

Link Analysis of Mobile Nodes in Ad Hoc Network Using Ricean Fading Channel Model

Communication channels are one of the important components of the wireless mobile ad hoc network. The link connectivity among mobile nodes moving in these channels can be measured through various performance metrics. This paper analysis the link connectivity of mobile nodes in one of the well known channel model, the Ricean fading channel, in which a strong dominant signal component is always present among several multipath signals received by receiver. Two performance matrices have been used to evaluate the link analysis of nodes. These are Link duration and Link ratio. It is discovered that the link duration is dependent on Ricean Factor K where as Link ratio shows irregular results, which represent true picture of link connectivity in the presence of fading.