Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 188-211). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--Auburn University, 2007. / The words "female" and "male" in the title are represented by the corresponding international symbols rather than by words. Abstract. Vita. Includes bibliographic references (ℓ. 38-42)

Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: G. Joan Holt. Vita. Includes bibliographical references.

Channels with state model communication settings where the channel statistics are not fully known or vary over transmissions. It is important for a communication system to obtain the channel state information in terms of increasing channel capacity. This thesis addresses the effect of the quality of state information on channel capacity. Extreme scenarios are studied to reveal the limit in increasing channel capacity with the knowledge of state information. We consider the channel with the perfect state information at the decoder, while the encoder is only available to a noisy state observation. The effect of the noisy state at the encoder to the channel capacity is studied. We show that for any binary-input channel if the mutual information between the noisy state observation at the encoder and the true channel state is below a positive threshold determined solely by the state distribution, then the capacity is the same as that with no encoder side information. A complementary phenomenon is also revealed for the generalized probing capacity. Extensions beyond binary-input channels are developed. We further investigate the channel capacity, when the causal channel state information (available at the encoder or the decoder or both) makes it deterministic. Every such a capacity is called an intrinsic capacity of the channel. Among them, the smallest and the largest called the lower and the upper intrinsic capacities, are particularly studied. Their exact values are determined in most cases when the input or the output is binary. General lower and upper bounds are also provided for the lower and the upper intrinsic capacities with causal state information available at both sides. Byproducts of this work are a generalization of the Birkhoff-von Neumann theorem and a result on the uselessness of causal state information at the encoder. / Thesis / Doctor of Philosophy (PhD) / It is well known that with the knowledge of channel state, it is possible to increase the channel capacity. In this sense, knowing channel state never hurts. However, whether it is always bene cial to actively acquire channel state is another story. If we take into account the cost of measuring the channel state against the potential gain on the capacity, sometimes it may not appear very economic to do so. This thesis studies the effect of the quality of observed channel states on the channel capacity. It has been found out in some circumstances the channel capacity is very sensitive to the noise on the state information. On the other hand, it appears that the maximum capacity can be achieved with the knowledge of a small portion of the total channel state information under a slightly different setting. This thesis proves the generality of such phenomena in binary-input channels and provides the necessary and sufficient conditions for the occurrence of such phenomena for an arbitrary channel. This paper also introduces the idea of intrinsic capacity which can be used to measure the ultimate capacity potential of a channel by exploring the channel state. By viewing an arbitrary channel as a deterministic channel with state, the greatest possible and smallest possible capacities have been either derived or bounded in the thesis.

No description available.

Kv1.2 is a member of the Shaker family of voltage-sensitive potassium channels and contributes to regulation of membrane excitability. The electrophysiological activity of Kv1.2 undergoes tyrosine kinase-dependent suppression in a process involving RhoA. We report that RhoA elicits suppression of Kv1.2 ionic current by modulating channel endocytosis. This occurs through two distinct pathways, one clathrin-dependent and the other cholesterol-dependent. Activation of RhoA downstream effectors Rho-kinase (ROCK) or protein kinase N (PKN) via the lysophosphatidic acid (LPA) receptor elicits clathrin-dependent Kv1.2 endocytosis and consequent attenuation of its ionic current. LPA-induced channel endocytosis is blocked by ROCK inhibition , dominant negative PKN, or by clathrin RNAi. In contrast, steady-state endocytosis of Kv1.2 in un-stimulated cells is cholesterol-dependent. Inhibition of basal ROCK with Y27632 or basal PKN with HA1077 increases steady-state surface Kv1.2. The Y27632-induced increase persists in the presence of clathrin RNAi and, in the presence of the sterol-binding agent filipin, does not elicit an additive effect. Temperature block experiments in conjunction with studies that perturb trafficking of newly synthesized proteins from the Golgi demonstrate that basal ROCK affects cholesterol-dependent trafficking by modulating the recycling of constitutively endocytosed Kv1.2 back to the plasma membrane. Both receptor-stimulated and steady-state Kv1.2 trafficking modulated by RhoA/ROCK require the activation of dynamin as well as the ROCK effector LIM kinase, indicating a key role for actin remodeling in RhoA-dependent Kv1.2 regulation.

<p>This thesis will setup and configure a channel sounding system, further it will set up a software environment for channel model extraction (characteristic of the channel) and evaluation.</p><p>The motivation of the project is to set up and configure a channel sounding system based a Spectral Analyzer (Agilent E4407B), Signal Generator (Agilent E8267D), Signal Studio and Matlab software. The main motivation is to evaluate capability of such a channel sounding system, and see if it can be used for future channel model extraction.</p><p>Channel Sounding is based on emitting RF signal from one antenna and receiving the RF signal at another antenna (spatial place), extracting the channel response. This project will start with getting familiar with the basic operation of the Spectral Analyzer (Agilent E4407B), the Signal Generator (Agilent E8267D) and Signal Studio. Then set up a channel sounding system with previous mentioned equipment. Then as practical exercise some channel sounding and channel model extraction will be conducted. Especially see what kind of parameters those are possible to extract, time delay, propagation paths etc.</p>

In this thesis, channel estimation technique in Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems is investigated. Channel estimation plays an important role in the receiver performance of the MIMO-OFDM systems. In this thesis, the Space-Frequency Block Codes - Orthogonal Frequency Division Multiplexing (SFBC-OFDM) structure with the superimposed training scheme are adopted to increase bandwidth efficiency. In addition to using the first-order statistics of the received signal to reduce the interference induced by the unknown signals, the modified least square (MLS) estimator and the decision-feedback scheme are combined together to improve the channel estimation. In contrast to the conventional interference cancellation scheme for channel estimations adopting the decision feedback mechanism, the structure of the SFBC is utilized to decrease the interference. Furthermore, the effects of the decision-feedback scheme with erroneous decisions upon channel estimation are also examined. Analytical results show that the proposed method has better performance and computation complexity is not increased.

In mobile communications, channel side information at transmitters can increasecapacity. For moving relays nodes, local nodes placed on buses and trams in urbanareas, the channel state information is outdated for control delays of severalmilliseconds, as in the LTE system. Prediction of the channel based on statistic is notadequate for vehicular velocities. In this thesis, prediction made with an additionalantenna, a ``predictor antenna", placed in front of the main antenna is evaluated. Thepredictor utilises that the channel of the predictor antenna is highly correlated to thechannel experienced by the main antenna somewhat later, when the main antenna hasmoved to the position previous occupied by the predictor antenna. A normalisedcorrelation of up to 0.98 could be measured between the channels of the antennasfor an antenna separation of several wavelengths, but it was found that the closeenvironment and the antenna pattern have a big impact on the correlation. Thepredictions made with the antenna are also combined with predictions based onstatistics of past measurements from the main antenna to see if a better result can beachieved. For a prediction range of 0.5 carrier wavelengths, a prediction as good as anormalised mean square error (NMSE) of -13.9 dB could be seen. This is sufficient togive a gain in the performance when using link adaptation and opportunistic multi-userscheduling, based on channel state information at transmitter. The evaluations isbased on measurements on a 20 MHz downlink channel at 2.68 GHz.