Abstract: System and methodologies for amplifier gain control in a communication system are provided herein. By leveraging similarities between the distribution of received signal samples in an MB-OFDM system and a Gaussian distribution, various algorithms described herein can be utilized to perform fast and low-complexity amplifier gain tuning. Received signal strength indication information corresponding to analog signal samples and/or digital signal samples obtained from an analog to digital converter are analyzed to obtain a signal energy distribution. The obtained signal energy distribution is then compared to a reference Gaussian distribution to adaptively tune an associated amplifier gain.

Abstract: Systems and methodologies for employing a multi-user Multiple Input Multiple Output (MIMO) relay protocol with self-interference cancellation in a wireless communication environment are provided herein. Data streams sent between user device(s) and base station(s) can traverse through a relay. Further, a decode and forward protocol can be employed by the relay rather than merely amplifying and forwarding the data streams. Moreover, each user device can listen to and decode data stream(s) sent by other user device(s) to the relay, and these decoded data stream(s) can be utilized for interference cancellation. Further, the user device(s) and the base station(s) can employ self-interference cancellation upon signals received from the relay. According to another example, an adaptive relay power allocation algorithm, which enhances power efficiency, can be leveraged by the relay for transmitting signals to the user device(s) and the base station(s).

Abstract: A robust closed-loop cross-layer design provides for the downlink multi-user multi-antenna systems with imperfect Channel State Information at the transmitter (CSIT) for slow fading channels. Using ACK/NAK feedbacks from mobiles, a closed-loop cross-layer scheduler does not require any knowledge of the CSIT error statistics. To take into account of the potential packet outage (due to imperfect CSIT), we define system goodput, which measures the average bits per second per Hertz (b/s/Hz) successfully delivered to the mobiles, as the optimization objectives. We formulate the cross-layer design as a mixed combinatorial search and Markov decision problem. Based on dynamic programming approach, the optimal power and rate allocation is determined using backward recursion and forward recursion algorithms. Simulations illustrate that the proposed closed-loop cross-layer scheduler has very robust goodput performance at moderate to high CSIT errors and pedestrian mobility.

Abstract: A training-based channel estimation technique is provided to estimate channel state information for MIMO systems that is highly energy efficient and optimal in terms of Cramér-Rao lower bound (CRLB). The technique employs loosely synchronized (LS) codes or shifted LS codes. The codes can be generated using a fast Golay correlator and an efficient Golay correlator. A low-complexity implementation is also provided.

Abstract: The disclosed subject matter relates to communicatively coupled cognitive radio systems, devices, methodologies, or combinations thereof, facilitating improved utilization of unused portions of spectral bands by secondary users generally allocated to other primary users. This improved utilization can be achieved by cooperative spectrum sensing employing ST coding and/or SF coding for transmit diversity. Further, cooperative spectrum sensing can be improved by employing relay diversity with or without algebraic coding. It is illustrated that a threshold probability of false alarm can be reduced by applying transmit diversity with space time coding and/or space frequency coding. It is further illustrated that relay diversity can be employed to compensate for reduced sensing diversity order were some nodes in a cooperative spectrum sensing system cannot report directly.

Abstract: The disclosed subject matter provides scheduling algorithms, methods, and systems that facilitate cross layer scheduling for systems with imperfect channel state information and unknown interference. By exploiting ACK/NAK feedback from users of downlink traffic and recursively optimizing scheduling policy components over a state space, the disclosed subject matter provide robust and optimal cross layer scheduling in the presence of unknown interference and imperfect channel state information. The disclosed details enable various refinements and modifications according to cross layer schedule and system design considerations.

Abstract: System and methodologies for reduced-complexity signal detection and decoding in a wireless communication system are provided herein. Systems and methodologies presented herein can utilize a relaxed form of the Lenstra-Lenstra-Lovasz (LLL) lattice reduction algorithm to reduce the complexity of lattice reduction operations in the context of MIMO detection. Additional systems and methodologies presented herein can apply lattice reduction in the context of a maximum likelihood (ML) detector for spherical or elliptical lattice space-time (LAST) codes.

Abstract: System and methodologies for low-distortion index assignment for quantization are provided herein. Various aspects described herein utilize a graph theoretic approach for determining an index assignment mapping between a quantization codebook and a signal constellation by employing a variation of the subgraph isomorphism problem. The graph theoretic index assignment algorithms described herein allow efficient determination of index assignment mappings for both binary and non-binary quantization schemes. Further, the topological structure of a signal constellation can be exploited to simplify the set of subgraphs to be searched in select cases. Various aspects described herein can additionally be utilized to determine index assignment mappings for space-time block codes in a multiple-input multiple-output wireless communication system.

Abstract: A Lenstra-Lenstra-Lovász (LLL)-based technique is utilized to reduce the complexity of a MIMO detector. Basis vectors can be pre-sorted, such as by V-BLAST ordering or sorted-QR ordering, prior to applying Gram-Schmidt Orthogonalization (GSO) to further improve performance. Alternatively, a joint sorting and LLL reduction (JSAR) technique can be utilized such that after each reduction step, a vector remaining to be reduced can be selected that will minimize the overall complexity. The JSAR technique can be applied on real or complex lattice bases. LLL reduction can be stopped after a predetermined threshold is exceeded.

Abstract: Efficient temporal search range predication for motion estimation in video coding is provided where complexity of using multiple reference frames in multiple reference frame motion estimation (MRFME) can be evaluated over a desired performance level. In this regard, a gain can be determined for using regular motion estimation or MRFME, and a number of frames if the latter is chosen. Thus, the computational complexity of MRFME and/or a large temporal search range can be utilized where it provides at least a threshold gain in performance. Conversely, if the complex calculations of MRFME do not provide sufficient benefit to the video block prediction, a smaller temporal search range (a less number of reference frames) can be used, or regular motion editing can be chosen over MRFME.

Abstract: A transmission protocol is provided for wireless communications in an OFDMA system that uses a rateless code and techniques are provided for dynamically adjusting the subcarrier resources allocated to an OFDMA relay node so that the relay is used at the right time according to the instantaneous channel state information (CSI). As a result, a higher throughput is achieved between source and destination nodes based on a low complexity algorithm for determining when relay assistance is helpful for completing a transmission between the source and destination nodes.

Abstract: A waveguide structure is described wherein microwaves or radio-frequency waves can be guided in their propagation through channels whose cross-sections contain fractal patterns, with relevant dimensions much smaller than the wavelengths of the guided waves. A finite section of such waveguide can be used as an efficient delay line.

Abstract: A joint set of linear precoder designs is provided for single cell uplink multiuser space-time block coded multiple-input multiple-output (MIMO) systems with multi-packet reception by exploiting outdated channel state information. By deriving the pairwise error probability with respect to both minimum and average codeword distance design metrics, the technique solves an optimization problem subject to transmit power constraint for each user and dependent on the outdated channel state information. Due to the non-convex nature of the optimization problem, an iterative technique based on alternating minimization and projected gradient can be used to solve for a joint linear preceding structure for general space-time block coding. The linear precoding structure is then sent from the base station to various consumer premise equipment for use in later transmissions. For orthogonal space-time block code, a simplified distributed technique is provided to solve for a closed-form solution of the optimization problem.

Abstract: A system, structure, and method of making the structure are disclosed for generating a large chemical potential difference between spin-up and spin-down electrons in non-magnetic materials. The device includes an inverse spin valve of a sandwiched layer structure with alternating non-magnetic and magnetic layers. In an embodiment of the invention, the structure is a tri-layer device with a magnetic layer sandwiched by two non-magnetic metals. Once the inverse spin valve structure is provided, an external electric field is applied to the inverse spin valve to generate a large chemical potential difference between the spin-up and spin-down electrons. In an embodiment of the invention, this feature is exploited to create a tunable light emitting diode or laser. In an embodiment of the invention, a dynamical magnetism is induced and controlled in the valve by an electric field. The dynamical magnetization may be used as spin source, or in electronic storage devices.

Abstract: A frequency-hopping pulse-width modulator is disclosed, which facilitates a switching regulator to use smaller-size inductive and capacitive elements, to have an improved power efficiency at light load, as well as predictable spectrum at different load levels. The improved modulator automatically determines the switching frequency of a switching regulator according to the load current delivered by the switching regulator from a number of pre-defined frequencies, which are all multiples of a fundamental frequency. By designing the maximum switching frequency of frequency-hopping pulse-width modulator in the MHz range, a switching regulator is able to use smaller-size inductive and capacitive elements. Light-load efficiency of the switching regulator with the frequency-hopping pulse-width modulator is also greatly improved as switching frequency of such switching regulator is reduced with decreased load current.

Abstract: A frequency compensation method for voltage-mode switching regulators is disclosed. A lowpass filter and a bandpass filter are employed in the two signal paths into the dual inputs of PWM comparators. In one embodiment, two zeros are generated to compensate for the L-C output filter poles. Stable operation, low output voltage ripple and fast load transient response are achieved; while the power consumption of error amplifier and the area for implementing on-chip passive components are greatly reduced.

Abstract: This invention provides a bistable liquid crystal device. The bistable liquid crystal device includes a first substrate having thereon a first conductive layer and a first alignment layer; a second substrate having thereon a second conductive layer and a second alignment layer; and a liquid crystal layer sandwiched between the first and second alignment layers. The first alignment layer induces a first pretilt angle ?1 in the range of 20°-65° between the liquid crystal layer in contact with the first alignment layer. The second alignment layer induces a second pretilt angle ?2 in the range of 20°-65° between the liquid crystal layer in contact with the second alignment layer. The liquid crystal layer is capable of maintaining a stable bend state or a stable splay state at zero bias voltage and is switchable between the stable bend state and the stable splay state when a switching energy is applied in operation to the liquid crystal layer.

Abstract: A fuel cell has at least one electrode having channels for delivering reactants, products, or both. The electrode is an anode or cathode of the fuel cell, or both. The electrode can serve as both a liquid diffusion layer and a flow field plate, thus replacing the traditional elements of carbon paper, cloth diffusion layer, and anode current collector. In some aspects, the fuel cell uses methanol, and the electrode is formed from flexible graphite. The electrode can have a structure sufficient to permit methanol diffusion while preventing methanol crossover. The electrode can also improve volumetric power density and eliminate contact resistance typically present between a conventional flow field plate and conventional diffusion electrode layer.

Abstract: This invention relates to a novel soy isoflavone product with high purities and strong biological activities and the method of producing the same from natural soybeans, soybean materials (i.e. tofu dregs, soy molasses) and other plant sources. The method includes three steps consisting of extraction with an organic solvent, hydrolysis using an acid and crystallization using an antisolvent. The procedure is very simple and thus can be easily adapted for large-scale manufacturing. Moreover, the procedure is able to produce a high yield of total isoflavones at a lower cost. HPLC analysis and E-Screen bioassay reveal that the obtained product not only contains a high content of isoflavone aglycones by weight of dry matter but also exhibits strong estrogenic activity toward human cells. Therefore, the product should be efficacious for relieving menopausal symptoms and other estrogen-deficient diseases and can be used in health care supplements or as additives for foods, beverages or cosmetics.

Abstract: The invention provides a bistable twisted nematic liquid crystal display, comprising a first substrate having thereon a first conductive layer and a first alignment layer; a second substrate having thereon a second conductive layer and a second alignment layer; a liquid crystal layer in the first and second alignment layers; an alignment layer on each of the substrates, the alignment layer imparting a preferred direction for liquid crystal molecules near the alignment layer, and possessing different azimuthal and polar anchoring energies when used to align a liquid crystal layer: the alignment layers being rubbed in such a way to give a stable twist angle of the liquid crystal of ? where ? can be any value in between ?45° to +45°; and wherein the d/p ratio of the liquid crystal layer is between the values of 0.15+0.5?/? and 0.35+0.5?/?.