Adaptive coding and transmitter diversity for slow fading channels

In this dissertation we consider several communications techniques to counteract the fading nature of the wireless channel. In particular we focus on the slow fading indoor channels, where the rate of change of the channel is low compared to the frame rate of the transmission system. In the present work we look at two methods to enhance the performance of the communications system: (i) the transmitter diversity system, and (ii) the Automatic Repeat Request (ARQ) protocols. In Chapter 2, we study the transmitter diversity system under the condition of the diversity channels being correlated. In Rayleigh fading, the performance of the diversity system deteriorates relative to the independent fading case. However, for the Rician fading system, when the specular diversity signals are not significantly out-of-phase with each other, we have discovered that the performance of the diversity system under correlated fading conditions can exceed the uncorrelated fading performance. In Chapter 3, we present a simple method to evaluate the throughputs of the basic ARQ protocols in slow fading channels. In Chapter 4, we design and analyse an adaptive ARQ/FEC protocol which changes the transmitter code-rate to match the channels conditions. The channel is estimated very simply from the implicit information contained in the ARQ feedback packets. The protocol is found to give a substantial gain over the basic ARQ protocols at almost all average SNR levels. In Chapter 5 we analyse a periodically switched antenna ARQ system. It is shown that at low fading rates this system is significantly superior to the single antenna system. In Chapter 5, we also analyse the performance of transmitter diversity ARQ systems. We have also proposed and analysed an adaptive ARQ/Diversity system in which the transmitter switches between the single and dual antenna transmission mode depending on the channel conditions. The adaptive ARQ/Diversity system has been found to significantly out-perform realistic block-coded systems

Adaptive coding and transmitter diversity for slow fading channels

In this dissertation we consider several communications techniques to counteract the fading nature of the wireless channel. In particular we focus on the slow fading indoor channels, where the rate of change of the channel is low compared to the frame rate of the transmission system. In the present work we look at two methods to enhance the performance of the communications system: (i) the transmitter diversity system, and (ii) the Automatic Repeat Request (ARQ) protocols. In Chapter 2, we study the transmitter diversity system under the condition of the diversity channels being correlated. In Rayleigh fading, the performance of the diversity system deteriorates relative to the independent fading case. However, for the Rician fading system, when the specular diversity signals are not significantly out-of-phase with each other, we have discovered that the performance of the diversity system under correlated fading conditions can exceed the uncorrelated fading performance. In Chapter 3, we present a simple method to evaluate the throughputs of the basic ARQ protocols in slow fading channels. In Chapter 4, we design and analyse an adaptive ARQ/FEC protocol which changes the transmitter code-rate to match the channels conditions. The channel is estimated very simply from the implicit information contained in the ARQ feedback packets. The protocol is found to give a substantial gain over the basic ARQ protocols at almost all average SNR levels. In Chapter 5 we analyse a periodically switched antenna ARQ system. It is shown that at low fading rates this system is significantly superior to the single antenna system. In Chapter 5, we also analyse the performance of transmitter diversity ARQ systems. We have also proposed and analysed an adaptive ARQ/Diversity system in which the transmitter switches between the single and dual antenna transmission mode depending on the channel conditions. The adaptive ARQ/Diversity system has been found to significantly out-perform realistic block-coded systems

LTE-BASED AERONAUTICAL MOBILE TELEMETRY - LAB AND FIELD TEST EXPERIMENTS

Aeronautical mobile telemetry (AMT) based on 3GPP’s LTE standard is implemented in a proof-of-concept system. The solution tackles the very high Doppler shifts expected in flight tests using an appliqué that can be inserted between the transmit/receive ports of the Test Article (TA) and the antennas. This appliqué estimates the Doppler shift and proactively compensates for it on the uplink signal being transmitted by the TA. The overall system has been tested under different operational conditions in a laboratory setup as well as in the field. In the laboratory setup, the desired operating conditions are created with a set of Software-Defined-Radio-based channel emulators coupled with a computer to control their behavior. In order to carry out field tests, an operational LTE network has been created at Edwards Air Force Base (EAFB) with two base stations, backhaul links, and a core network. In this paper, we provide descriptions of both laboratory and field test setups as well as the results of several tests that have been carried out to date. The results of lab and field tests lend strong support to the viability of this AMT solution.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection