Development of accurate physical layer models is very important for generating realistic network simulation results. Significant effort has been put into setting up physical layer models for wireless channels that emulate the impact of the channel on the higher layers of the network. Setting up the models is especially difficult for a frequency selective channel. In this thesis the use of non-linear functions to convert the frequency selective channel to an equivalent flat fading channel is examined. The analytical expressions for the statistics of the equivalent flat fading process that are needed to set up the physical layer models are derived. These results are used to set up the physical layer model for the frequency selective channel. Extensive simulations are performed to verify the accuracy of the model against a detailed physical layer implementation. The statistics of the model and the actual channel are seen to match, validating the method of setting up the models.

No description available.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / This paper investigates the application of iterative equalization techniques to overcome multipath fading for shaped offset QPSK (SOQPSK) in aeronautical telemetry. Two iterative equalization techniques for turbo encoded SOQPSK are presented. The first is the optimal-MAP turbo equalizer for OQPSK. The second equalizer is the adaptive decision feedback equalizer. Simulation shows that in the presence of frequency selective multipath typically encountered in aeronautical telemetry, both of these equalizers exhibit impressive performance.

No description available.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Initial results of wideband channel sounding experiments sponsored by the Advanced Range Telemetry (ARTM) program are presented. Data collected at Edwards EAFB during the Winter 1998-1999, are analyzed in the frequency domain to estimate the number, strength, and delays of the significant multipath reflections observed during the experiments. We observe that the channel is adequately modeled using two or three multipath reflections. The multipath fade events are correlated with recorded bit error rates and transmitter location to provide a comprehensive overview of the channel characteristics. Summaries from two test flights are included where it is seen that the 2- and 3-ray channel models provide excellent models for the data. In general, the 3-ray model captures the essential features of the multipath interference. In this model the first multipath is a strong specular reflection with relative amplitude greater than 0.5 and relative delay in the 30 to 70 ns range. The second multipath is a much weaker reflection with relative amplitude less than 0.5 and relative delay in the 175 to 325 ns range.

International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Methods to improve reception during multipath fading of telemetry data received aboard ships participating in missile exercises include various diversity techniques. Among these techniques are polarization, angle, height, and frequency diversity. In this paper, a two-ray multipath model is used to investigate the various techniques and determine the merits of each. Possible ways of implementing the promising ones are discussed.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper is the first of two papers that present a multipath channel model for wideband aeronautical telemetry. Channel sounding data, collected at Edwards AFB, California at both L-Band and lower S-Band, were used to generate channel model. In Part 1, analytic and geometric considerations are discussed and the frequency domain modeling technique is introduced. In Part 2, the experimental results are summarized and a channel model composed of three propagation paths is proposed.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper is the second of two papers that present a multipath channel model for wideband aeronautical telemetry. Channel sounding data were collected at Edwards AFB, California at both L-Band and lower S-Band. Frequency domain analysis techniques were used to evaluate candidate channel models. The channel model is composed of three propagation paths: a line-of-sight path, and two specular reflections. The first specular reflection is characterized by a relative amplitude of 70% to 96% of the line-of-sight amplitude and and a delay of 10 – 80 ns. This path is the result of “ground bounces” off the dry lake bed at Edwards and is a typical terrain feature at DoD test ranges located in the Western USA. The amplitude and delay of this path are defined completely by the flight path geometry. The second path is a much lower amplitude path with a longer delay. The gain of this path is well modeled as a zero-mean complex Gaussian random variable. The relative amplitude is on the order of 2% to 8% of the line-of-sight amplitude. The mean excess delay is 155 ns with an RMS delay spread of 74 ns.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper uses ARTM channel sounding data collected at Edwards Air Force Base to investigate the dependency between the characteristics of frequency selective multipath fading and carrier frequency and ground based received antenna diameter. Channel model parameters are obtained from data sets measured at different frequencies and various ground based antenna diameters. The analysis shows that the multipath characteristics do not statistically change between the L-band and S-band carrier frequencies, but do change with antenna diameter. Furthermore, Flight 18 data shows that antenna diversity may be a useful technique to reduce data loss from multipath fading.

In this thesis, the blind phase estimator algorithms are studied, including Histogram Algorithm (HA), Modified Histogram Algorithm (MHA), Maximum Likelihood (ML), 4th power-law and modified 4th power-law to compare their performance under quadrature amplitude modulation and additive white gaussian noise(AWGN) channel. Owing to the development of wireless communication, I used the fading channel of wireless communication and studied the performance of all algorithms again. After differential encoding and quadrature amplitude modulation, signals enter additive white gaussian noise(AWGN), constant phase offset and fading channel. At receiver, I use the above estimator to find the phase offset. If there is not line of sight under fading channel, all estimators performance are not good from simulation results, if there is a strong line of sight, all estimators performance are good and approximate to the AWGN channel.