The advancement in the CATV industry has been remarkable. In the beginning, CATV provided a few television channels. Now it provides a variety of advanced services such as video on demand (VOD), Internet access, Pay-Per-View on demand and interactive TV. These advances have increased the popularity of CATV manyfold. Current improvements focus on interactive services with high quality. These interactive services require more upstream (transmission from customer premises to cable operator premises) channel bandwidth. The flow of data through the CATV network in both the upstream and downstream directions is governed by a standard referred to as the Data Over Cable Service Interface Specification (DOCSIS) standard. The latest version is DOCSIS 3.1, which was released in January 2014. The previous version, DOCSIS 3.0, was released in 2006. One component of the upstream communication link is the QAM demodulator. An important component in the QAM demodulator is the equalizer, whose purpose is to remove distortion caused by the imperfect upstream channel as well as the residual timing offset and frequency offset. Most of the timing and frequency offset are corrected by timing and frequency recovery circuits; what remains is referred to as offset. A DOCSIS receiver, and hence the equalizer within, can be implemented with ASIC or FPGA technology. Implementing an equalizer in an ASIC has a large nonrecurring engineering cost, but relatively small per chip production cost. Implementing equalizer in an FPGA has very low non-recurring cost, but a relatively high per chip cost. If the choice technology was based on cost, one would think it would depends only on the volume, but in practice that is not the case. The dominant factor when it comes to profit, is the time-to-market, which makes FPGA technology the only choice. The goal of this thesis is to design a cost optimized equalizer for DOCSIS upstream demodulator and implement in an FPGA. With this in mind, an important objective is to establish a relationship between the equalizer’s critical parameters and its performance. The parameter-performance relationship that has been established in this study revealed that equalizer step size and length parameters should be 1/64 and approximately 20 to yield a near optimum equalizer when considering the MER-convergence time trade-off. In the pursuit of the objective another relationship was established that is useful in determining the accuracy of the timing recovery circuit. That relationship establishes the sensitivity both of the MER and convergence time to timing offset. The equalizer algorithm was implemented in a cost effective manner using DSP Builder. The effort to minimize cost was focused on minimizing the number of multipliers. It is shown that the equalizer can be constructed with 8 multipliers when the proposed time sharing algorithm is implemented.

Ion channel regulation is key to the control of excitability and behaviour. In the bag cell neurons of Aplysia californica, a voltage- and Ca2+-dependent nonselective cation channel drives a ~30-minute afterdischarge, culminating in the release of egg-laying hormone. Using excised, inside-out single channel patch-clamp, this study tested the hypothesis that inositol 1,4,5-trisphosphate (IP3), which is produced during the afterdischarge, and channel-associated protein kinase C (PKC), which is activated throughout the afterdischarge, cause a left-shift (enhancement) in both the voltage- and Ca2+-dependence of the cation channel. Kinetic analysis of bag cell neuron cation channel voltage-dependence revealed that, with depolarization, the channel remained open longer and reopened more often. A cation channel subconductance was also observed, and found to be 13 pS vs. the typical 23 pS full-conductance. The cytoplasmic face of cation channel-containing patches was exposed to 1 mM ATP, as a phosphate source for channel-associated PKC, and/or 5 uM IP3. Apparent PKC-dependent phosphorylation left-shifted voltage-dependence by -3 mV, although this effect was more prominent at negative voltages (between -90 and -30 mV). Conversely, IP3 right-shifted voltage-dependence (change in V1/2 of 6 mV). Cation channel Ca2+-dependence was similar to that previously reported, with a control EC50 of 3-5 uM. This was right-shifted by PKC (EC50 = 30 uM) and even more so by IP3 (apparent EC50 = 20 M). PKC largely rescued the Ca2+ responsiveness in the presence of IP3 (EC50 = 20 uM). Unexpectedly, IP3 plus ATP resulted in an increase in channel unitary conductance at more positive voltages. The multi-faceted regulation of the bag cell neuron cation channel suggests sophisticated modulatory control. Upregulation, such as depolarization and the left-shift in voltage-dependence with PKC, would drive the afterdischarge, while counteracting effects, such as IP3 right-shifting voltage-dependence, as well as PKC and IP3 suppressing Ca2+-dependence, would simultaneously or subsequently attenuate the channel, thus preventing an interminable afterdischarge. / Thesis (Master, Physiology) -- Queen's University, 2008-08-26 13:20:16.528

Tandem source-channel coding is proven to be optimal by Shannon given unlimited delay and complexity in the coders. Under low delay and low complexity constraints, joint source-channel coding may achieve better performance. Although digital joint source-channel coding has shown a noticeable gain in terms of reconstructed signal quality, coding delay, and complexity, it suffers from the leveling-off effect. However, analog systems do not suffer from the leveling-off effect. In this thesis, we investigate the advantage of analog systems based on the Shannon-Kotel’nikov approach and hybrid digital-analog coding systems, which combine digital and analog schemes to achieve a graceful degradation/improvement over a wide range of channel conditions. First, we propose a low delay and low complexity hybrid digital-analog coding that is able to achieve high (integer) expansion ratios ( >3). This is achieved by combining the spiral mapping with multiple stage quantizers. The system is simulated for a 1 : 3 bandwidth expansion and the behavior for a 1 : M (with M an integer >3) system is studied in the low noise level regime. Next, we propose an analog joint source-channel coding system that is able to achieve a low (fractional) expansion ratio between 1 and 2. More precisely, this is an N : M bandwidth expansion system based on combining uncoded transmission and a 1 : 2 bandwidth expansion system (with N < M < 2N).Finally, a 1 : 2 analog bandwidth expansion system using the (Shannon-Kotel’nikov) Archimedes’ spiral mapping is used in the compressed sensing context, which is inherently analog, to increase the system’s immunity against channel noise. The proposed system is compared to a conventional compressed sensing system that assumes noiseless transmission and a compressed sensing based system that account for noise during signal reconstruction. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2011-07-29 02:30:11.978

Based on preliminary reports, an extended series of bolamphiphilic oligoester compounds with structural symmetry were synthesized and then tested using a planar bilayer experiment with the voltage-clamp technique. The main structures of these compounds are identical, consisting of a mono or tri-aromatic core, two octamethylene chains and two benzoyl headgroups which are all connected through ester linkages. The structural variance was provided by the four differently functionalized benzoyl headgroups. The synthetic methods of three to five steps were mainly adapted from the previously reported method.1 The methods successfully produced eight compounds with overall yields of 20 to 30%. The voltage-clamp data suggested voltage-dependent behaviors occur at low concentrations while Ohmic behaviors require at high concentrations. The activity at low potentials showed relatively erratic behavior but the channels frequently switched between opening and closing states. The activity at high potential lasted longer as the channel maintained a longer state of opening. The exponential voltage-dependent behaviors were observed at higher potential while the voltage-independent Ohmic behaviors occur at low potential. These channel behaviors are highly time-dependent as there is no control over the stability and the aggregation level for the compounds forming active channels in the membrane. In some cases the current-voltage responses appear to be asymmetrical between the positive and the negative potentials. Mechanisms consistent with the observations are proposed. / Graduate / 0485 / 0490 / yzong@uvic.ca

The definition of polar codes given by Arikan is explicit, but the construction complexity is an issue. This is due to the exponential growth in the size of the output alphabet of the bit-channels as the codeword length increases. Tal and Vardy recently presented a method for constructing polar codes which controls this growth. They approximated each bit-channel with a “better” channel and a “worse” channel while reducing the alphabet size. They constructed a polar code based on the “worse” channel and used the “better” channel to measure the distance from the optimal channel. This thesis considers the knowledge gained from the perspective of the “better” channel. A method is presented using iterative upgrading of the bit-channels which successively results in a channel closer to the original one. It is shown that this approach can be used to obtain a channel arbitrarily close to the original channel, and therefore to the optimal construction of a polar code. / Graduate / 0984 / 0544 / arash.ghayoori@gmail.com

Based on preliminary reports, an extended series of bolamphiphilic oligoester compounds with structural symmetry were synthesized and then tested using a planar bilayer experiment with the voltage-clamp technique. The main structures of these compounds are identical, consisting of a mono or tri-aromatic core, two octamethylene chains and two benzoyl headgroups which are all connected through ester linkages. The structural variance was provided by the four differently functionalized benzoyl headgroups. The synthetic methods of three to five steps were mainly adapted from the previously reported method.1 The methods successfully produced eight compounds with overall yields of 20 to 30%. The voltage-clamp data suggested voltage-dependent behaviors occur at low concentrations while Ohmic behaviors require at high concentrations. The activity at low potentials showed relatively erratic behavior but the channels frequently switched between opening and closing states. The activity at high potential lasted longer as the channel maintained a longer state of opening. The exponential voltage-dependent behaviors were observed at higher potential while the voltage-independent Ohmic behaviors occur at low potential. These channel behaviors are highly time-dependent as there is no control over the stability and the aggregation level for the compounds forming active channels in the membrane. In some cases the current-voltage responses appear to be asymmetrical between the positive and the negative potentials. Mechanisms consistent with the observations are proposed. / Graduate / 0485 / 0490 / yzong@uvic.ca

The advent of turbo codes in 1993 represented a significant step towards realising the ultimate capacity limit of a communication channel, breaking the link that was binding very good performance with exponential decoder complexity. Turbo codes are parallel concatenated convolutional codes, decoded with a suboptimal iterative algorithm. The complexity of the iterative algorithm increases only linearly with block length, bringing previously unprecedented performance within practical limits. This work is a further investigation of turbo codes and other concatenated schemes such as the multiple parallel concatenation and the serial concatenation. The analysis of these schemes has two important aspects, their performance under optimal decoding and the convergence of their iterative, suboptimal decoding algorithm. The connection between iterative decoding performance and the optimal decoding performance is analysed with the help of computer simulation by studying the iterative decoding error events. Methods for good performance interleaver design and code design are presented and analysed in the same way. The optimal decoding performance is further investigated by using a novel method to determine the weight spectra of turbo codes by using the turbo code tree representation, and the results are compared with the results of the iterative decoder. The method can also be used for the analysis of multiple parallel concatenated codes, but is impractical for the serial concatenated codes. Non-optimal, non-iterative decoding algorithms are presented and compared with the iterative algorithm. The convergence of the iterative algorithm is investigated by using the Cauchy criterion. Some insight into the performance of the concatenated schemes under iterative decoding is found by separating error events into convergent and non-convergent components. The sensitivity of convergence to the Eb/Ng operating point has been explored.

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Magnesium, the second most abundant cation in the cell, is involved in a diverse range of biochemical activities. This project focuses on the mechanism of magnesium import into the cell through the action of Alr1p. Alr1p resides in the plasma membrane of yeast and belongs to the CorA-Alr1p-Mrs2p family of magnesium channels. Potential regulators of CorA were found through genetic screening and yeast two-hybrid screens have pulled out interactors of Alr1p. Interactors that influence Alr1p and its conformation will, with very high probability, also change the channel’s ability for magnesium import. Membrane proteins are not easily amenable to traditional yeast two-hybrid screens due to their hydrophobic nature. The goal of this thesis is to identify interactors of Alr1p using iMYTH, a modified yeast two-hybrid method. Of the eighteen Alr1p interactors identified, Vma3p and Vma11p, which are both subunits of the V-ATPase, showed the most promise for further Alr1p interaction characterizations.