Abstract: The invention is directed to devices that allow for simultaneous multiple biochip analysis. In particular, the devices are configured to hold multiple cartridges comprising biochips comprising arrays such as nucleic acid arrays, and allow for high throughput analysis of samples.

Abstract: Selected mapping (SLM) peak-power reduction is distortionless as it selects the actual transmit signal from a set of alternative signals, which all represent the same information. The specific signal generation information needs to be transmitted and carefully protected against bit errors. Here, me propose an extension of SLM, which employs scrambling and refrains from the use of explicit side information in the receiver. Some additional complexity and nearly vanishing redundancy is introduced to achieve markedly improved transmit signal statistics. Even though SLM is applicable with any modulation, we concentrate on orthogonal frequency-division multiplexing (OFDM) in this letter.

Abstract: Orthogonal frequency-division multiplexing (OFDM) systems are highly sensitive to synchronization errors. We introduce an algorithm for the blind estimation of symbol timing and carrier frequency offset in wireless OFDM systems. The proposed estimator is an extension of the Gini-Giannakis (see IEEE Trans. Commun., vol.46, p.400-411, 1998) estimator for single-carrier systems. It exploits the cyclostationarity of OFDM signals and relies on second-order statistics only. Our method can be applied to pulse shaping OFDM systems with arbitrary time-frequency guard regions, OFDM based on offset quadrature amplitude modulation, and biorthogonal frequency-division multiplexing systems. We furthermore propose the use of different subcarrier transmit powers (subcarrier weighting) and periodic transmitter precoding to achieve a carrier frequency acquisition range of the entire bandwidth of the OFDM signal, and a symbol timing acquisition range of arbitrary length. Finally, we provide simulation results demonstrating the performance of the new estimator.

Abstract: An adaptable orthogonal frequency-division multiplexing system (OFDM) that uses a multiple input multiple output (MIMO) to having OFDM signals transmitted either in accordance with time diversity to reducing signal fading or in accordance with spatial diversity to increase the data rate. Sub-carriers are classified for spatial diversity transmission or for time diversity transmission based on the result of a comparison between threshold values and at least one of three criteria. The criteria includes a calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix.

Abstract: A pipelined digital data receiver for a cable TV headend which is capable of receiving DOCSIS 1.0 or 1.1 or advanced PHY TDMA or SCDMA bursts having programmable symbol rates and programmable modulation types as well as a host of other burst parameters such at Trellis code modulation on or off, scrambling on or off, various values for Reed-Solomon T number and codeword length. The receiver has an RF section to filter and digitize incoming RF signals. It also has an input section to detect impulse noise and do match filtering and despread SCDMA bursts. A timing recovery section recovers the symbol clock and detects the start of bursts and collisions. A rotational amplifier and equalizer calculate and track gain, phase and frequency offsets and correct symbols and calculates equalization coefficients. A decoder section decodes TCM and non TCM bursts, and a Reed-Solomon decoder section reconstructs RS codewords and uses them to error correct the payload data.

Abstract: Future cellular systems will employ spatial multiplexing with multiple antennas at both transmitter and receiver to take advantage of large capacity gains. In such systems it will be desirable to select a subset of available transmit antennas for link initialization, link maintenance, or handoff. In this paper we present a criteria for selecting the optimal antenna subset in terms of minimum error rate, when coherent receivers, either linear or maximum likelihood (ML), are used over a slowly varying channel. For the ML receiver we propose to pick the subset whose output constellation has the largest minimum Euclidean distance. For the linear receiver we propose use of the post-processing SNRs (signal to noise ratios) of the multiplexed streams whereby the antenna subset that induces the largest minimum SNR is chosen. Simulations demonstrate that our selection algorithms also provides diversity advantage thus making subset selection useful over fading channels.

Abstract: Several smart antenna systems have been proposed and demonstrated at the base station (BS) of wireless communications systems, and these have shown that significant system performance improvement is possible. We consider the use of adaptive antennas at the BS and mobile stations (MS), operating jointly, in combination with orthogonal frequency-division multiplexing. The advantages of the proposed system includes reductions in average error probability and increases in capacity compared to conventional systems. Multiuser access, in space, time, and through subcarriers, is also possible and expressions for the exact joint optimal antenna weights at the BS and MS under cochannel interference conditions for fading channels are derived. To demonstrate the potential of our proposed system, analytical along with Monte Carlo simulation results are provided.

Abstract: Two erbium-doped fiber ring lasers (EDFRLs) wvith simultaneous emission at four different wavelengths are demonstrated. Both systems employ fiber Bragg gratings (FBGs) to select the operation wavelengths within the ring. The sensing capability of the FBGs has been taken advantage of, allowing for the sources to be used as sensor multiplexing schemes. The first system employs four FBGs in a tree filter topology, achieving four output channels with -5 dBm power each. The second system comprises an in-line filtering topology with active fiber segments within the filter. This second source yields 2-dBm output signals and allows for a higher number of lines to be easily added to the system. A comparison between both topologies is carried out, and their capability for sensor multiplexing is demonstrated.

Abstract: The adoption of orthogonal frequency-division multiplexing (OFDM) by wireless local area networks and audio/video broadcasting standards testifies to the importance of recovering block precoded transmissions propagating through frequency-selective FIR channels. Existing block transmission standards invoke bandwidth-consuming error control codes to mitigate channel fades and training sequences to identify the FIR channels. To enable low-complexity block-by-block receiver processing, we design redundant precoders with cyclic prefix (CP) and superimposed training sequences for optimal channel estimation and guaranteed symbol recovery regardless of the underlying FIR frequency-selective channels. Numerical results axe presented to access the performance of the designed training and precoding schemes.

Abstract: The design of a pilot symbol for orthogonal frequency-division multiplexing packet detection and synchronization is presented. Algorithms are described for packet detection and for synchronization using maximum likelihood estimation of channel frequency offset, phase offset for coherent detection, and subsample timing offset. The efficacy of the detection and synchronization algorithms is demonstrated experimentally.

Abstract: A digital video broadcast (DVB) device decoder as part of a digital residential entertainment system (DRES) is disclosed. A media server, such as a broadband multimedia gateway (BMG), sends an entire transport layer, rather than a single program stream, over a Network Bus to a digital video broadcast (DVB) device decoder. The transport layer includes multiple program, data and information streams. For example, the transport layer may include multiple MPEG signals, such as MPEG-2 signals. The media server provides the DVB tuning function with integrated Personal Video Recording (PVR) functionality. The DVB device decoder provides decrypting, demultiplexing, decoding and digital-to-analog conversion. The complexity of the media server is minimized because it only has to decode a transport layer rather than decoding a single stream of data. The combination of entertainment video and data streams on the same transport is also optimized for the purpose of providing enhanced multimedia services.

Abstract: The orthogonal frequency-division multiplexing access technique has been attracting considerable interest especially for wireless local area networks (WLANs). We consider the joint estimation of the symbol timing, the channel length and the channel-impulse response. A novel estimation algorithm based on maximum-likelihood principles and the generalized Akaike information criterion are proposed. We provide simulation results to illustrate the performance of our proposed algorithm.

Abstract: From the Publisher: Addresses the needs of those interested in learning the science and engineering of mobile and wireless communications. Readers are given the analytical tools, fundamental physics and communications theory, along with a comprehensive list of references. Topics include propagation effects, wireless modems, multiplexing techniques, 3G and OFDM systems.

Abstract: This invention provides a highly flexible multiplexing scheme for Direct Sequence CDMA systems enabling the CDMA system to flexibly allocate CDMA channel resources between packet-switched broadcast channels and fast-circuit-switched dedicated channels in order to optimize system throughput. A method and system are provided for operating a communication system. The method has steps of: flexibly allocating CDMA channel resources between packet-switched broadcast channels and fast-circuit-switched dedicated channels in order to optimize system throughput, and employing a side channel as required to send all or a part of a total amount of data, depending on the total amount of the data. A bandwidth allocation scheme allocates a set of CDMA channels for burst packet-switched channels, and data is time division multiplexed over the set of burst CDMA channels providing a wide bandwidth data pipe for packet-switched data.. Subscriber stations are equipped with multiple CDMA channel receivers tuned to the burst CDMA channels.

Abstract: A network includes a plurality of antennas coupled to a plurality of base stations. The network can be optical or constructed with RF microwave links. The antennas and base stations are configured to transmit and receive digital signals representing cellular signals and the digital signals are exchanged over the network. A plurality of links couple the plurality of antennas and the plurality of base stations. At least one link of the plurality of links provides multiple transmission paths between at least a portion of the base stations and at least a portion of the antennas.

Abstract: We consider the performance analysis and the receiver design of low-density parity-check (LDPC) code based space-time coded (STC) orthogonal frequency-division multiplexing (OFDM) system over correlated frequency- and time-selective fading channels.

Abstract: This paper describes multiplexing schemes for interferometric fiber sensors based on time-division multiplexed and dense wavelength-division multiplexing using optical add/drop multiplexers. The results of an experimental arrangement, which is based on one of the architectures, is also presented. Topics include a discussion of the noise sources in the system, dynamic range, and a characterization of the distributed feedback fiber laser source noise. We show the crosstalk levels in the experimental arrangement to be between -47 and -76 dB depending on the mechanism involved. The multiplexing schemes demonstrate the potential to address at least 192 interferometric sensors through two fibers based on a system with six wavelengths with a phase resolution less than 20 /spl mu/rad//spl radic/Hz. For application to sonar arrays, our analysis has shown that hydrophones multiplexed in this type of architecture would achieve ambient acoustic noise-limited pressure resolution with an in-water dynamic range up to 135 dB at frequencies up to 10 kHz. In general, these architectures would find application in systems requiring very large numbers of sensors with a minimum of telemetry cabling required.

Abstract: Multiplexing is the transmission of two or more messages simultaneously over the same communication channel in a way that enables them to be separated and used at the receiving end. The normal visual system provides us with a very wide field of view at an apparent high resolution. The wide field of view is continuously monitored at a low resolution, providing information for navigation and detection of objects of interest. These objects of interest are sampled over time using the high-resolution fovea. Most disabling visual conditions impact only one of the components, the peripheral low-resolution wide field or the central high-resolution fovea. The loss of one of these components prevents the interplay of central and peripheral vision needed for normal function and causes disability. Traditionally low-vision aids replace or supplement the missing function, but usually at a cost of a significant loss in the surviving function. For example, magnifying devices increase resolution but reduce the field of view, whereas minifying devices increase the field of view but reduce resolution. A proposal to resolve many of the problems of current visual aids by exploring a general engineering approach--vision multiplexing--that takes advantage of the dynamic nature of human vision is presented. Vision multiplexing seeks to provide both the wide field of view and the high-resolution information in ways that could be accessed and interpreted by the visual system. This paper describes the use of optical methods and computer technologies in the development of a number of new visual aids, all of which apply vision multiplexing to restore the interplay of central and peripheral vision using eye movements in a natural way.

Abstract: Disclosed is a system for allowing on-demand delivery of data, such as MPEG-2 compressed video data, to a subscriber from a content server. The system utilizes a managed IP network that is coupled to the one or more content servers that allows the content servers to deliver data such as video, audio, and textual data with a guaranteed quality of service that is at least as good as broadcast quality service. The managed IP network is connected to a head end or other local cable service provider where video is delivered locally to subscribers. The IP transport data is translated to MPEG transport data, multiplexed onto an MPEG transport system, digitally modulated onto an rf carrier and up-converted to a specific frequency channel. The signal is then applied to the cable for delivery to the subscriber. Upstream signaling occurs through a set top box or computer that is connected to the cable and subsequently to a digital modulator/demodulator and ISP to a managed IP network 66. Low band signals can also be transmitted from the content servers back to the set top box or computer indicating confirmation of an order. Also, control signals such as stop, rewind, fast-forward, and slow can be transmitted back to the content server to control the transmission of data from the content server to the subscriber.

Abstract: As electronic devices get smaller and smaller, so the probability of errors in manufacturing increases, and the need to use fault-tolerant techniques. This paper compares the relative performance of four such techniques: R-fold multiple redundancy; cascaded triple modular redundancy; von Neumann's multiplexing method; and a reconfigurable computer technique. It is shown that manufacturing defect rates of the order of 0.01 to 0.1 will require enormous amounts of redundancy, of the order of 10/sup 3/ to 10/sup 5/.

Abstract: We propose an efficient channel estimation technique for orthogonal frequency-division multiplexing (OFDM) systems with transmitter diversity. The proposed technique estimates uniquely all channel frequency responses needed in space-time coded OFDM systems using "comb-type" training symbols. The computational complexity of the proposed technique is reduced dramatically, compared with the previous minimum mean-squared error (MMSE) technique, due to the all the processing being done in the frequency-domain. Also, several other techniques for mitigating the random noise effect and tracking channel variation are discussed to further improve the performance of the proposed approach. The performances of the proposed approach are demonstrated by computer simulation for mobile wireless channels.

Abstract: The invention proposes a method and a unit for controlling the flow of at least one TCP connection between a sender and a receiver. The method is of the type which consists in controlling, at the level of a given multiplexing node through which TCP segments relevant to the connection pass, a window size parameter contained in acknowledgement segments sent back by the receiver. The method comprises the steps of: a) receiving an acknowledgement from the receiver on the up link (receiver to sender) of the connection at the level of said given multiplexing node; b) controlling a window size parameter contained in, said acknowledgement segment on the basis of the difference between, firstly, a first context value associated with the TCP connection, defined as being the sequence number of the last segment that was transmitted from said given multiplexing node on the down link (sender to receiver) of the connection, to which the length of said segment is added, and, secondly, the sequence number indicated in said acknowledgement segment; c) transmitting the acknowledgement segment to the sender the up link of the connection from said multiplexing node with the window size parameter thus controlled.

Abstract: Data throughput rates are increased in an optical fiber communication system without requiring replacement of the existing optical fiber in a link. Channel throughput is increased by upgrading the components and circuitry in the head and terminal of an optical fiber communication system link. Aggregate throughput in a fiber optic link is increased beyond the range of conventional Wavelength Division Multiplexed (WDM) upgrades, while precluding the necessity of replacing existing fiber plants. The increase in system throughput is achieved by using advanced modulation techniques to encode greater amounts of data into the transmitted spectrum of a channel, thereby increasing the spectral efficiency of each channel. This novel method of increasing transmission capacity by upgrading the head and terminal of the system to achieve greater spectral efficiency and hence throughput, alleviates the need to replace existing fiber plants. Spectrally efficient complex modulation techniques can be supported by interface circuits with an increased level of signal processing capability in order to both encode multiple bits into a transmitted symbol and decode the original data from the received symbols.

Abstract: A method of preparing data streams to facilitate seamless switching by a switching device (20) to produce an output data stream without any switching artifacts. Bi-directional switching between any plurality of data streams is supported. The data streams (48) are divided into segments, wherein the segments includes synchronized starting points and end points. The data rate is increased before an end point of a segment. Gap may be inserted between the segments. Increasing the data rate can include increasing a bandwidth of the plurality of data streams, for example by multiplexing, or compressing the data. The present invention can be used with media data streams, for example with MPEG encoded transport streams.

Abstract: A performance analysis of algorithms for maximum likelihood estimation of channel parameters for orthogonal frequency-division multiplexing packet detection and synchronization is presented. The detection and synchronization algorithms, which are based on the use of a pilot symbol, are described in Coulson (2001). The performance analyses concentrate on operation in additive white Gaussian noise channels, and the accuracy of these analyses are demonstrated using experimental and simulation data. Methods to extend these analyses to frequency flat multipath fading channels are presented.

Abstract: Conventional orthogonal frequency-division multiplexing receivers disregard the guard interval in channels with small dispersion even though its unconsumed portion can be exploited for improved demodulation by applying a Nyquist-shaped window in the receiver. The transmitter does not need to be modified, subcarrier orthogonality in the receiver is preserved, and the receiver discrete Fourier transform size can be retained. Windowing can mitigate the joint effect of additive noise and intercarrier interference among subcarriers caused by the carrier frequency offset. A closed solution for optimum window coefficients suited to this scenario is derived.

Abstract: A method and apparatus for multiplexing a plurality of channels within a multimedia system includes processing that begins by receiving a plurality of channels from a multimedia source. The processing then continues by receiving a plurality of channel selection commands from client modules. The processing continues by selecting a channel of the plurality of channels for each of the channel selection commands to produce selected channels. As such, for each channel selection command, a corresponding channel is selected from the plurality of channels. The processing continues by encoding the selected channels based on a data conveyance protocol (e.g., encoding scheme and/or modulation scheme). The encoded channel data is then conveyed to a plurality of clients.

Abstract: The paper analyzes the performance of the downlink channel of a multimedia interactive service system which transmits the desired information by the frequency multiplexing of several OFDM signals compliant with the DVB-T standard. The effects of the nonlinear distortions introduced by a high power amplifier on the system performance are evaluated both in terms of the bit error rate (BER) degradation in AWGN channels and of the spectral regrowth. The performance comparison to the case of a single DVB-T signal as well as the benefits of an ideal predistortion is also considered by comparing analytical results to computer simulations.

Abstract: A method and apparatus for wireless transmission of a digital bit stream (102). The method employs diversity techniques to minimize multipath fading. Digital bits are converted into symbols (S1 to Sn) and the symbols are provided to a number of diversity branches (109). Each diversity branch has its own antenna (114). The symbols sent to each diversity branch may be multiplied by a different phase factor or amplitude factor. The phase factors and the amplitude factors may be randomly selected. Channel quality measurements are used to select the phase and amplitude factors. The symbols can be grouped into frames before transmission. The frames can be multiplied by matrices comprising phase and amplitude factors. The frames can undergo cyclic shifting, which provides an additional measure of diversity.