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. 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. 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.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 155-177). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Vita. Includes bibliographical references (leaves 153-167). Also available in an electronic version.

Thesis (M.S.)--University of North Carolina at Wilmington, 2006. / Includes bibliographical references (leaves: 73)

In the communication of multimedia content, certain dependency structure often exists among the source-coded messages by different source coding techniques, where by "dependency" we mean the dependent contributions of the messages to the overall reconstruction quality. Motivated by such notion of dependency, this thesis considers the problem of communicating dependent source-coded messages over compound channels, which include the attractive wireless channels and packet-loss channels. In this thesis we propose a novel framework to model arbitrary dependency structure among source-coded messages from the source-reconstruction perspectives, and formulate the problem of communicating such messages over compound channels as the problem of maximizing the average utility at the receiver. Over discrete memoryless channels (DMC), we derive the expression of maximal achievable utility, which appears to be governed by the channel coding theorem. Over degraded compound channels, we study analytically the maximal achievable utility by superposition codes. To achieve the maximal utility, the encoder chooses the best sub-chain in the utility graph and encodes it using the best superposition code. For the case of two source-coded messages, we show that the maximal utility achieved by superposition codes is the maximum among all coding schemes. Since in practice layered codes (LC) and multiple description codes (MDC) are two most attracted source coding schemes which induce different dependency structures among coded messages, we numerically evaluate the maximal achievable utility for sources coded with those two source coding schemes communicated over DMC and degraded compound channels respectively, and show the impact of communication delay and channel condition on their respective achievable utilities. In addition, for communicating a Gaussian N(0,1) independent identically distributed (i.i.d.) sequence over degraded compound channels, the joint source channel coding schemes are considered and the minimal achievable distortion is derived and compared for different combinations of source and channel codes. It is shown that the combination of LC and superposition codes outperforms other coding schemes. The comparative behaviour among those techniques is further demonstrated by the experimental results. Practically, we study the performances of various coding schemes for communicating two dependent messages over quasi-static Rayleigh fading channels, which include conventional channel codes, time sharing codes, and a low-density parity-check (LDPC) based coding scheme, termed Bi-LDPC codes. The success rates and the throughput of the considered coding schemes are compared. For communicating a Gaussian N(0,1) source sequence encoded by LC and MDC respectively over quasi-static Rayleigh fading channels, the average distortion is also compared among different channel coding schemes. It appears that Bi-LDPC codes, conventional channel codes encoding both messages, and time sharing type-2 (TS-2) codes, each has their advantage over different region of signal-to-noise ratio (SNR), compared with each other.

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Mutagenesis studies on the four EF-hands of KChIP2.2 (Potassium channel-interacting protein 2.2) were carried out to explore the conformational transition upon the binding of Ca2+ and Mg2+ and the subsequent effect on the interaction between KChIP2.2 and Kv4.2. CD spectra indicated that Ca2+- and Mg2+-loaded wild-type and mutated KChIP2.2 altered the secondary structure contents. In contrast to other mutants, mutation on EF1 caused a notably change in the secondary structure of KChIP2.2. Fluorescence measurement revealed that EF-hands 3 and 4 were high affinity Ca2+-binding sites within KChIP2.2 molecule, but the binding of Mg2+ with KChIP2.2 was marginally affected by EF-hand mutations. The results of size-exclusion chromatography showed that mutations on EF-1, EF-2 and EF-3 induced the oligomerization of KChIP2.2 and the extent of oligomerization was enhanced by Ca2+ and Mg2+. No significant differences were noted when wild-type and mutated KChIP2.2 bound with porcine brain membrane and liposome either in the absence or presence of Ca2+- and Mg2+. Pull down assay showed that KChIP2.2 and EF-hand mutants could bind with Kv4.2 in the absence of Ca2+ and Mg2+, but the interaction was enhanced by Ca2+ and Mg2+. However, the binding capability of mutants for Kv4.2 was notably lower than that observed for wild-type KChIP2.2. It was found that, in sharp contrast to that EF1 mutant exclusively localized in the nucleus, the other EF-hand mutants and wild-type protein distributed within nucleus as well as cytoplasm. Elevating intracellular Ca2+ concentration caused the translocation of EF1 mutant to cytoplasm but no appreciable effect on other mutants and wild-type KChIP2.2. . Taken together, these results suggest that the integrity of the four EF-hands are involved in function to stabilize conformation for binding with Kv channel, but this conformational transition is not essential for the binding to cell membrane.