Computer simulation is now increasingly being used for design and performance evaluation of communication systems. When simulating a mobile wireless channel for communication systems, it is usually assumed that the fading process is a random variate with Rayleigh distribution. The random variates of the fading process should also have other properties, like autocorrelation, spectrum, etc. At present, there are a number of methods to generate the Rayleigh fading process, some of them quite recently proposed. Due to the use of different Rayleigh fading generators, different simulations of the same communication system yield different results. Three methods, viz., the Jakes method, the IDFT method and the filtering WGN method, have been studied, simulated and compared based on the Rayleigh fading process' properties. Various communication systems have been simulated using the Rayleigh fading generators and the difference in the results, if any, have been analyzed. The research studies the different Rayleigh fading generators and compares them using the properties of the Rayleigh fading channel. It is found that the IDFT method and the filtering WGN method generate processes that have properties very close to the ideal Rayleigh fading process.

In mobile radio systems, the bandwidth of spread spectrum signals for CDMA system is very wide. If the bandwidth exceeds the coherence bandwidth of the channel, the signal is transmitted in the frequency-selective channel, and the signal is severely distorted by the multiple propagation paths. Each bandwidth of the signals for Multi-Carrier CDMA system is smaller. If the bandwidth is smaller than the coherence bandwidth of the channel, the channel is said to be frequency-nonselective. Besides, the data rate of Multi-carrier-CDMA is higher than the data rate of CDMA. If the traditional combing detector is used for Multi-Carrier CDMA system, the channel coefficients have to be estimated first. The error of the estimated channel coefficients will result in the performance of detector degrade. The blind adaptive algorithm doesn

Approved for public release; distribution is unlimited. / Wireless communication is employed to connect mobile computers in a networked environment for information exchange. In a tactical space, sensors and computers typically need to operate on-the-move while transmitting data over both short and long distances in different terrain and conditions. The wireless communication is thus susceptible to effects of Doppler shift and channel fading. In addition, when security and anti jamming features are required, such as frequency-hopping techniques, then coherent signal detection is difficult and noncoherent modulation is used instead. Our study will focus on the bit error rate (BER) performance analysis of noncoherent orthogonal modulation, specifically M-ary frequency-shift keying (MFSK) and code-shift keying (CSK) modulation, in both additive white Gaussian noise (AWGN) and for a Rayleigh fading channel with Doppler shift. The potential applications include communications between mobile computer-sensor devices, such as a mobile ground control station maintaining a datalink with UAV. / Civilian

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / The aeronautical channel is an air to ground channel characterized by multipath, high doppler shifts, Rayleigh fading and noise. Use of a channel sounder ensures proper estimation of the parameters associated with the impulse response of the channel. These estimates help us to characterize the radio channels associated with aeronautical telemetry. In order to have a satisfactory channel characterization, the amplitudes, phase shifts and delays associated with each multipath component in the channel model must be determined.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / While investigating methods for more efficiently allocating the available spectrum researchers noticed that in many geographical locations, there are broad bands of frequencies that are lightly utilized. Such inefficiencies are inevitable with fixed spectral allocation rules. Cognitive Radios actively measure the spectral utilization and adapt their modulation, frequencies, bandwidths, power, etc. to take advantage of these lightly used “spectral holes” or “white spaces”. Much of the research work in cognitive radios has not taken into account some of the challenges faced in the telemetry community-including multipaths and a guaranteed quality of service. This paper highlights how some mathematical models of adaptive modulation discussed extensively in many research papers and textbooks can be used in Cognitive Radios as well.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, we extended the matched filter bound (MFB) of time-discrete multipath Rayleigh fading channels derived in [1,2] for multiscale wavelet signaling communication.

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / Spatial modulation (SM) is a transmission scheme where only one transmit antenna is active at any time instant. It thus reduces interchannel interference (ICI) and receiver complexity over traditional multi-antenna systems. However, the spectral efficiency of SM is low. To improve the spectral efficiency, generalized spatial modulation (GSM) can be used. In this paper, we propose to apply the Alamouti technique with GSM for correlated antennas, and show that the proposed approach provides significant improvement over conventional SM and GSM. Our study also shows the importance of bit-to-antenna mappings and their roles on the selection of appropriate correlated antennas.

Demand for capacity in wireless communication systems has been rapidly growing world- wide. This has been driven by increasing data rate requirements of cellular mobile systems, and demand for wireless Internet and multimedia services. As the available radio spec- trum is limited, higher data rates can only be achieved by designing more efficient signaling techniques. In this thesis, we propose a new transmission scheme, which benefits from the advantages of conventional space-time trellis codes (CSTTCs) but does not have the disadvantages, especially for larger signal constellations. We achieve this by developing a new class of codes, called Multilevel Space-Time Trellis Codes (IMLSTTC). The new scheme provides a scalable and promising alternative to CSTTCs, by providing the system designer with the flexibility to choose any desired balance between code performance, complexity and throughput. The proposed scheme outperforms layered schemes at high SNRs, using a smaller number of antennas.

Multiple antennas help in combating the destructive effects of fading as well as improve the spectral efficiency of a communication system. Receive diversity techniques like maximal ratio receive combining have been popular means of introducing multiple antennas into communication systems. Space-time block codes present a way of introducing transmit diversity into the communication system with similar complexity and performance as maximal ratio receive combining. In this thesis we study the performance of space-time block codes in Rayleigh fading channel. In particular, the quasi-static assumption on the fading channel is removed to study how the space-time block coded system behaves in fast fading. In this context, the complexity versus performance trade-off for a space-time block coded receiver is studied. As a means to improve the performance of space-time block coded systems concatenation by convolutional codes is introduced. The improvement in the diversity order by the introduction of convolutional codes into the space-time block coded system is discussed. A general analytic expression for the error performance of a space-time block coded system is derived. This expression is utilized to obtain general expressions for the error performance of convolutionally concatenated space-time block coded systems utilizing both hard and soft decision decoding. Simulation results are presented and are compared with the analytical results. / Master of Science

As there is a rapid growth in the field of wireless communications, the demand for various multimedia services is also increasing. The data that is being transmitted suffers from distortions through source encoding and transmission over errorprone channels. Due to these errors, the quality of the content is degraded. There is a need for service providers to provide certain Quality of Experience (QoE) to the end user. Several methods are being developed by network providers for better QoE.The human tendency mainly focuses on distortions in the Region of Interest(ROI) which are perceived to be more annoying compared to the Background(BG). With this as a base, the main aim of this thesis is to get an accurate prediction quality metric to measure the quality of the image over ROI and the BG independently. Reduced Reference Image Quality Assessment (RRIQA), a reduced reference image quality assessment metric, is chosen for this purpose. In this method, only partial information about the reference image is available to assess the quality. The quality metric is measured independently over ROI and BG. Finally the metric estimated over ROI and BG are pooled together to get aROI aware metric to predict the Mean Opinion Score (MOS) of the image.In this thesis, an ROI aware quality metric is used to measure the quality of distorted images that are generated using a wireless channel. The MOS of distorted images are obtained. Finally, the obtained MOS are validated with the MOS obtained from a database [1].It is observed that the proposed image quality assessment method provides better results compared to the traditional approach. It also gives a better performance over a wide variety of distortions. The obtained results show that the impairments in ROI are perceived to be more annoying when compared to the BG.