Abstract: Described herein are systems and methods for multiplexing pipelined data for backup operations. Various data streams are combined such as by multiplexing by a multiplexing module. The multiplexing module combines the data from the various data streams received by receiver module(s) into a single stream of chunks. The multiplexing module may combine data from multiple archive files into a single chunk. Additional modules perform other operations on the chunks of data to be transported such as encryption, compression, etc. The data chunks are transmitted via a transport channel to a receive pipeline that includes a second receiver module and other modules. The data chunks are then stored in a backup medium. The chunks are later retrieved and separated such as by demultiplexing for restoring to a client or for further storage as auxiliary copies of the separated data streams or archive files.

Abstract: Techniques for multiplexing and transmitting multiple data streams are described. Transmission of the multiple data streams occurs in “super-frames”. Each super-frame has a predetermined time duration and is further divided into multiple (e.g., four) frames. Each data block for each data stream is outer encoded to generate a corresponding code block. Each code block is partitioned into multiple subblocks, and each data packet in each code block is inner encoded and modulated to generate modulation symbols for the packet. The multiple subblocks for each code block are transmitted in the multiple frames of the same super-frame, one subblock per frame. Each data stream is allocated a number of transmission units in each super-frame and is assigned specific transmission units to achieve efficient packing. A wireless device can select and receive individual data streams.

Abstract: In this paper, the authors propose a next-generation hybrid WDM/TDM optical access network architecture called Stanford University aCCESS or SUCCESS. This architecture provides practical migration steps from current-generation time-division multiplexing (TDM)-passive optical network (PONs) to future WDM optical access networks. The architecture is backward compatible for users on existing TDM-PONs, while simultaneously capable of providing upgraded high-bandwidth services to new users on DWDM-PONs through advanced WDM techniques. The SUCCESS architecture is based on a collector ring and several distribution stars connecting the CO and the users. A semipassive configuration of the Remote Nodes (RNs) enables protection and restoration, making the network resilient to power failures. A novel design of the OLT and DWDM-PON ONUs minimizes the system cost considerably: 1) tunable lasers and receivers at the OLT are shared by all ONUs on the network to reduce the transceiver count and 2) the fast tunable lasers not only generate downstream data traffic but also provide DWDM-PON ONUs with optical CW bursts for their upstream data transmission. Results from an experimental system testbed support the feasibility of the proposed SUCCESS architecture. Also, simulation results of the first SUCCESS DWDM-PON MAC protocol verify that it can efficiently provide bidirectional transmission between the OLT and ONUs over multiple wavelengths with a small number of tunable transmitters and receivers.

Abstract: A spread spectrum receiver processes signals from a plurality of sources modulated by different spread spectrum codes by sampling the signals as received to produce an integer series of sampling segments at a sampling rate at least twice a chip rate of the codes, each sampling segment containing an integer number of bits representing a fraction of a chip of the codes, time division multiplexing each sample segment into a number of channels, correlating the bits in each sample segment in each channel in parallel with a source specific series of locally generated sequential code samples differing by one bit, summing each parallel correlation, and accumulating the summed parallel correlations for each code sample in each channel at a rate at least equal to the chip rate to derive data related to each of the sources.

Abstract: Optical burst switching (OBS) is a promising switching technology to exploit the potential benefits of optical communication and, at the same time, support statistical multiplexing of data traffic at a fine granularity. To quantify its benefits, the paper describes several typical burst assembly algorithms and studies their impact on the assembled burst traffic characteristics as well as the performance of TCP traffic. Also described is a proactive burst scheduling algorithm, called burst overlap reduction algorithm (BORA), which schedules locally assembled bursts in such a way as to reduce burst contention at downstream nodes in OBS networks. Furthermore, to provide analytical insights into performance evaluation of OBS networks, a burst loss model at an OBS node and its extension to different reservation protocols are presented.

Abstract: Feature Issue on Optical Interconnection Networks (OIN) We describe a low-latency, high-throughput scalable optical interconnect switch for high-performance computer systems that features a broadcast-and-select architecture based on wavelength- and space-division multiplexing Its electronic control architecture is optimized for low latency and high use Our demonstration system will support 64 nodes with a line rate of 40 Gbit/s per node and operate on fixed-length packets with a duration of 512 ns using burst-mode receivers We address the key system-level requirements and challenges for such applications

Abstract: A novel approach of blind channel estimation for orthogonal frequency-division multiplexing (OFDM) systems is proposed. A linear transformation is applied on each block before it enters the OFDM system. The transform imposes a correlation structure on the transmitted blocks, which is exploited at the receiver to recover the channel via simple cross-correlation operations. The proposed approach is computationally simple and converges fast, which makes it a good candidate for estimation of fast-varying channels. Its performance is tested analytically, through a mean-square error analysis, and also via simulations. Results show that it compares favorably to the training-based scheme used in the IEEE 802.11a wireless standard.

Abstract: We describe the design and implementation of a high-data-rate high-capacity digital holographic storage disk system. Various system design trade-offs that affect density and data-rate performance are described and analyzed. In the demonstration system that we describe, high-density holographic recording is achieved by use of high-resolution short-focal-length optics and correlation shift multiplexing in photopolymer disk media. Holographic channel decoding at a 1-Gbit/s data rate is performed by custom-built electronic hardware. A benchmark sustained optical data-transfer rate of 10 Gbits/s has been successfully demonstrated.

Abstract: This work presents general classes of optimal training signals for estimation of frequency-selective channels in MIMO OFDM systems. Basic properties of the discrete Fourier transform are used to derive the optimal training signals which minimize the channel estimation mean square error. Both single and multiple OFDM training symbols are considered. Several optimal pilot tone allocations among the transmit antennas are presented and classified as frequency division multiplexing, time division multiplexing, code division multiplexing in frequency-domain, code division multiplexing in time-domain, and combinations thereof. All existing optimal training signals in the literature are special cases of the presented optimal training signals and our designs can be applied to pilot-only schemes as well as pilot-data multiplexed schemes.

Abstract: Techniques for multiplexing multiple data streams using frequency division multiplexing (FDM) in an OFDM system are described. M disjoint “interlaces” are formed with U usable subbands. Each interlace is a different set of S subbands, where U=M·S. The subbands for each interlace are interlaced with the subbands for each of the other M−1 interlaces. M slots may be defined for each symbol period and assigned slot indices 1 through M. The slot indices may be mapped to interlaces such that (1) frequency diversity is achieved for each slot index and (2) the interlaces used for pilot transmission have varying distances to the interlaces used for each slot index, which improves channel estimation performance. Each data stream may be processed as data packets of a fixed size, and different numbers of slots may be used for each data packet depending on the coding and modulation scheme used for the data packet.

Abstract: The paper proposes an adaptive selection algorithm for surviving symbol replica candidates based on the maximum reliability in ML detection with QR decomposition and M-algorithm (QRM-MLD) for OFCDM MIMO multiplexing. In the proposed algorithm, symbol replica candidates newly-added at each stage are ranked for each surviving symbol replica from the previous stage using multiple quadrant detection. Then, branch metrics are calculated only for the limited number of symbol replica candidates with high reliability based on an iterative loop in increasing order of the accumulated branch metrics from the candidate with the minimum one. Simulation results show that the computational complexity of the proposed algorithm from the viewpoint of the number of real multiplications is reduced to approximately 1/6 and 1/1900, respectively, compared to that of the original QRM-MLD and that of the conventional MLD with squared Euclidian distance calculations for all symbol replica candidates, assuming the identical achievable average block error rate (BLER) performance in 4-by-4 MIMO multiplexing with 16QAM data modulation. The results also show that 1-Gbps throughput is achieved at the E/sub b//N/sub 0/ per receiver antenna of approximately 9 dB using the adaptive selection algorithm in QRM-MLD associated with 16QAM modulation and turbo coding with coding rate of 8/9, assuming a 100-MHz bandwidth for a twelve-path Rayleigh fading channel (rms delay spread, 0.26 /spl mu/sec; maximum Doppler frequency, 20 Hz).

Abstract: Preface. Retrieving Files from the Wiley FTP and Internet Sites. 1. Performance Evaluation in Telecommunications. 2. Probability and Random Processes Review. 3. Application of Birth and Death Processes to Queueing Theory. 4. Networks of Queues: Product Form Solution. 5. Markov Chains: Application to Multiplexing and Access. 6. The M/G/1 Queue: Imbedded Markov Chains. 7. Fluid Flow Analysis. 8. The Matrix Geometric Techniques. 9. Monte Carlo Simulation. Index.

Abstract: A PLD includes at least one portion of the programmable interconnect that can be time multiplexed. The time multiplexed interconnect allows signals to be routed on shared interconnect at different times to different destinations, thereby increasing the functionality of the PLD. Multiple sources can use the same interconnect at different times to send signals to their respective destinations. To ensure proper sharing of the interconnect, the sources can include selection devices (such as multiplexers), and the destinations can include capture devices (such as flip-flops), wherein the selection devices and the capture devices are controlled by the same time multiplexing signal. To optimize the time multiplexing interconnect, as much of the same interconnect is shared as possible.

Abstract: This paper proposes likelihood function generation of complexity-reduced maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD) suitable for soft-decision turbo decoding and investigates the throughput performance using QRM-MLD with the proposed likelihood function in multipath Rayleigh fading channels for orthogonal frequency and code division multiplexing (OFCDM) with multiple-input multiple-output (MIMO) multiplexing Simulation results show that by using the proposed likelihood function generation scheme for soft-decision turbo decoding following QRM-MLD in 4-by-4 MIMO multiplexing, the required average received signal energy per bit-to-noise power spectrum density ratio (E/sub b//N/sub o/) at the average block error rate (BLER) of 10/sup -2/ at a 1-Gbps data rate is significantly reduced compared to that using hard-decision decoding in OFCDM access with 16 QAM modulation, the coding rate of 8/9, and 8-code multiplexing with a spreading factor of 8 assuming a 100-MHz bandwidth Furthermore, we show that by employing QRM-MLD associated with soft-decision turbo decoding for 4-by-4 MIMO multiplexing, the throughput values of 500 Mbps and 1 Gbps are achieved at the average received E/sub b//N/sub o/ of approximately 45 and 93 dB by QPSK with the coding rate of R = 8/9 and 16 QAM with R = 8/9, respectively, for OFCDM access assuming a 100-MHz bandwidth in a twelve-path Rayleigh fading channel

Abstract: Wireless Orthogonal Frequency Division Multiplexing and/or Orthogonal Frequency Division Multiple Access (OFDM/OFDMA) and/or Time-Frequency Division Multiplexing and/or Time-Frequency Division Multiple Access (T-FDM/T-FDMA) systems and methods include forward and return link carriers (112, 122) comprising number of sub-carrier groupings (110, 120) that are not identical. A return link carrier (122) may consist of fewer sub-band carriers than a forward link carrier (112) and the return link carrier (122) also may consist of a single sub-band carrier.

Abstract: A digital payload for processing a sub-band spectrum received on an uplink beam at a communications satellite includes a digital channelizer, a digital switch matrix and a digital combiner. The digital channelizer divides the sub-band spectrum into a plurality of frequency slices that can be routed by the digital switch matrix to any of a number of receiving ports. A digital combiner receives the frequency slices and re-assembles them to form one or more output sub-bands for transmission on an output beam of the communications satellite. The digital payload may also include an embeddable digital regeneration module configured to demodulate some or all of the sub-band spectrum to extract a digital bitstream therefrom. The digital bitstream may be processed to implement code-based multiplexing, switching, access control, and other features.

Abstract: A new trellis shaping design is proposed for reducing the peak-to-average power ratio of the bandlimited orthogonal frequency-division multiplexing (OFDM) signals. The approach is based on recursive minimization of the autocorrelation sidelobes of an OFDM data sequence. A novel metric in conjunction with the Viterbi algorithm is devised. The performance of the trellis shaping depends on signal mapping strategy, and the two types of mapping, referred to as Type-I and Type-II, are proposed. The Type-I mapping has no capability of reducing the average power, but it can achieve a significant reduction of the peak-to-average power ratio. On the other hand, the Type-II mapping is designed to achieve both peak and average power reduction. The bit error probability of the system over an AWGN channel is evaluated based on the simulations, which confirms the effectiveness of the proposed scheme.

Abstract: The performance of the phase-shifted superstructured fiber Bragg grating (SSFBG) for optical code (OC) recognition was investigated with different reflectivity as well as input pulse width. The auto-correlation peak (PA) and the ratios of PA to the maximum wing level (P/W) and cross-correlation level (P/C) were used to quantitatively evaluate the OC recognition performance. There is a conflict between obtaining high PA and high P/W and P/C ratios in high reflectivity regime. The approach of applying apodization technique to improve the performance in high reflectivity regime is proposed. The comparative experimental investigations with 127-chip 160-Gchip/s SSFBG are carried out to confirm the effectiveness of the proposed approach. Error-free transmission with multiplexing of two active users has been successfully achieved by the apodized SSFBG at a data rate of 1.25 Gbit/s.

Abstract: Multiple wireless communication standards can be supported in a single radio apparatus by time interleaving communications with the multiple communication standards. A single radio can be controlled to time interleave communications standards to successively activate a single communication channel for each of the communication standards. The single radio device can be configured to order the supported communication standards in a hierarchy to provide priority to certain communications. Time interleaving wireless communications over standards that support burst communications, such as time multiplexed wireless communication systems or wireless packet data systems, allows a single radio to seamlessly support multiple with no loss of data.

Abstract: This work presents a wide class of digital signal-processing schemes for orthogonal frequency-division multiplexing (OFDM) transmission which combine a nonlinear operation in the time domain and a linear filtering operation in the frequency domain. The ultimate goal of these schemes is to reduce the envelope fluctuation of ordinary OFDM, while keeping its high spectral efficiency and allowing a low-cost, power-efficient implementation. An appropriate statistical model concerning the transmitted frequency-domain blocks is developed, which is derived from well-established results on Gaussian stochastic processes distorted by memoryless nonlinearities. This model can be employed for performance evaluation by analytical means, with highly accurate results whenever the corresponding conventional OFDM signals exhibit quasi-Gaussian characteristics. Cases where the signal-processing scheme is repeatedly used, in an iterative way, are treated through an extension of the proposed statistical modeling. A set of numerical results is presented and discussed so as to show the practical interest of both the proposed schemes and the analytical methods for evaluation of their performance. For the sake of comparisons, this paper includes numerical results concerning the partial transmit sequence technique, which is an alternative peak-to-mean envelope power ratio-reducing technique of higher complexity, often recommended due to its distortionless nature. The superior performance/complexity tradeoffs through the proposed class of nonlinear signal-processing schemes is emphasized.

Abstract: On-chip source-synchronous serial communication has many advantages over multi-bit parallel communication in the aspects of skew, crosstalk area cost, wiring difficulty, and clock synchronization. However, the serial wire tends to dissipate more energy than parallel bus due to the bit multiplexing. We propose a coding method to reduce the transmission energy of the serial communication by minimizing the number of transitions on the serial wire. We demonstrate the significant energy saving in a multimedia application, 3D graphics. We also apply the coding technique to a CMOS SoC implementation which integrates various processing units with packet switched on-chip networks.

Abstract: Capacitive microfabricated ultrasonic transducers (cMUTs) recently produced clinical-quality images, and have the potential to enable true 3D ultrasound. Much has been written about the value of integrating cMUTs with electronics, and some early work has been published (Eccardt, P.-C. et al., 1996; Noble, R.A. et al., 2002). The paper describes monolithic integration of high-quality imaging cMUTs with analog switching electronics. The switching circuitry used has the same voltage limitations as commercial multiplexing chips (200 V/sub PP/). Water tank results demonstrate that cMUTs integrated with controlling switches are fully-functional when the capacitance and resistance of the switch are inserted into the cMUT model. The results further demonstrate no measurable effect of the switch on the radiation pattern of the acoustic elements. This verifies the viability of aperture control and channel multiplexing with monolithically integrated electronics. In the short term, such integration can allow for reconfigurable apertures, arrays with many elevation rows, and optimal preamplification. it also represents a step towards a practical 2D matrix transducer, due to the density of its integration and the freedom to optimize separately the cMUT and the integrated electronics.

Abstract: Introduction to Fiber Optic Communications.Fundamentals of Optics.Characteristics of Optical Fibers.Fiber and Cable Fabrication.Sources and Transmitters.Detectors and Receivers.Fiber Optic Devices.Modulation, Multiplexing and Network Architecture.Fiber Optic Communications Systems.Fiber Optic Test and Measurement.Other Lightwave Communications Applications.

Abstract: A system for measuring liquid level in multiple tanks using optical fiber technology has been developed. Oil field service industry or any sector requiring liquid level measurements in flammable atmospheres can be benefited from this intrinsically safe technology. The device used a single lens for the emitting and receiving fiber and it is based on amplitude variations as a function of the liquid distance and not in time of flight or phase detection. Being the first fiber-optic liquid level sensor with those characteristics for long ranges (>200 cm). A simple model to describe their behavior has been derived and tested on two prototypes. A Monte-Carlo method is used to fit the experimental data and obtain the model parameters. High accuracy between experimental data and fitted curve is obtained. The prototypes have a good linearity, better than 1.5% FS (full scale). Sensor heads are made of plastic optical fibers (POF) that are easy to handle, flexible and economical. They are excited by 650 nm lasers, housed in ST-connectors to obtain compact and rough prototypes. Optical multiplexing is used to increase the measuring safety area. Frequency division multiplexing is used to address each sensor head. A discussion about the influence of tilts and aberrations is also included.

Abstract: Pilot and data transmission schemes for multi-antenna communication systems utilizing multi-carrier modulation are provided. Subband multiplexing is used to avoid interference resulting from transmitting multiple signals simultaneously from multiple antennas. M usable subbands are initially arranged to form multiple groups of subbands, with each group including a different subset of the usable subbands. Each of T transmit antennas is then assigned one or possibly more subband groups for pilot transmission and typically one subband group for data transmission. Pilot and data may then be transmitted from each antenna on the subbands assigned to that antenna for pilot and data transmission. For each transmit antenna, the transmit power for each assigned subband may be scaled higher such that all of the total transmit power available for the antenna is used for transmission. Pilot and/or data may be transmitted simultaneously from all T antennas on all usable subbands without causing mutual interference.

Abstract: A widespread design for multiple-input multiple-output (MIMO) radio channel measurement devices (sounders) is based on time-division multiplexed switching of a single transmit/receive radio frequency (RF) chain into the elements of a transmit/receive antenna array. While being cost-effective, such a solution can cause significant measurement errors due to phase noise in the local oscillators. We analyze the impact of phase noise on MIMO channel measurement accuracy and show that it can lead to overestimation of channel capacity of up to 100% in practice. Furthermore, we demonstrate that the impact of phase noise is most pronounced if the physical channel has low rank (typical for line-of-sight or low scattering scenarios). The extreme case of a rank-1 physical channel is analyzed in detail.

Abstract: Pseudo-differential multiplexer circuits and methods. The circuit input signals are provided to two similar multiplexers, one of which is driven by true signals and one by the complementary input signals. No matter what the values of the circuit input signals, at least one of the two multiplexers always selects a low value. Therefore, at least one of the two multiplexers has the capability of overcoming a value stored in an output circuit (e.g., a latch) coupled to the output terminals of the two multiplexers. Thus, even when neither multiplexer can provide a high signal at the full value of power high VDD, the output circuit provides the correct output value. The invention also encompasses methods of selecting between circuit input signals by utilizing a pseudo-differential multiplexing technique, e.g., utilizing multiplexer circuits similar to those described above.

Abstract: Techniques for efficient signaling to a plurality of mobile stations are disclosed. In one embodiment, each of a plurality of symbol streams are encoded with one of a plurality of covering sequences, the covered symbol streams are combined to form a Code Division Multiplexed (CDM) signal, and the CDM signal is further covered by another covering sequence for code division multiplexing with one or more additional signals for transmission to a remote station. In another embodiment, a plurality of CDM signals are formed from the covered symbol streams, and the plurality of CDM signals are Time Division Multiplexed (TDM) prior to the further covering. In other embodiments, decovering and demultiplexing is performed to recover one or more of the symbol streams. Various other aspects are also presented. These aspects have the benefit of providing efficient utilization of the reverse link capacity, accommodating varying requirements such as low-latency, high throughput or differing quality of service, and reducing forward and reverse link overhead for providing these benefits, thus avoiding excessive interference and increasing capacity.

Abstract: This paper deals with the capacity behavior of single carrier modulation with frequency-domain equalization (SC-FDE) systems in broad-band multipath fading environments for the case where the channel is unknown at the transmitter and perfectly known at the receiver. The capacity performance of SC-FDE system is compared with that of orthogonal frequency-division multiplexing (OFDM) system. And the influence of the propagation environment and system parameters on capacity of these systems is studied. A useful conclusion is obtained that the expected capability of the SC-FDE is always poorer than that of OFDM in frequency-selective fading channel, and it is closer to OFDM in channel with lower delay spread. Furthermore, it is found that although the expected capacity of SC-FDE decreases with increasing delay spread, the outage probability may decrease as a result of the frequency diversity.