Abstract: DFT-based channel estimation methods and systems are disclosed. One system includes an inverse discrete Fourier transform module, a noise power estimator, a noise filter and a discrete Fourier transform module. The inverse discrete Fourier transform module is configured to determine time domain estimates by applying an inverse discrete Fourier transform to initial channel estimates computed from pilot signals. Additionally, the noise power estimator is configured to estimate noise power by determining and utilizing time domain samples that are within a vicinity of sinc nulls of the time domain estimates. The noise filter is configured to filter noise from the time domain estimates based on the estimated noise power to obtain noise filtered time domain estimates. Further, the discrete Fourier transform module is configured to perform a discrete Fourier transform on the noise filtered time domain estimates to obtain frequency domain channel estimates for channels on which pilot signals are transmitted.

Abstract: A method includes evaluating an optical signal spectrum for estimated filtering parameters of an optical spectral filtering device for shaping optical signal spectrum, determining a feedback for fine tuning the optical spectral filtering device for nonlinearity tolerance enhancement in the optical transmission system, responsive to received optical signal quality in the optical signal spectrum; and using the feedback to adjust said optical spectral filtering device for predetermined shaping and predetermined fiber nonlinearity tolerance in the optical transmission system.

Abstract: Disclosed are methods and structures of Multiple Kernel learning framed as a standard binary classification problem with additional constraints that ensure the positive definiteness of the learned kernel. Advantageously, the disclosed methods and structures permit the use of binary classification technologies to develop better performing, and more scalable Multiple Kernel Learning methods that are conceptually simpler.

Abstract: Disclosed is a general learning framework for computer implementation that induces sparsity on the undirected graphical model imposed on the vector of latent factors. A latent factor model SLFA is disclosed as a matrix factorization problem with a special regularization term that encourages collaborative reconstruction. Advantageously, the model may simultaneously learn the lower-dimensional representation for data and model the pairwise relationships between latent factors explicitly. An on-line learning algorithm is disclosed to make the model amenable to large-scale learning problems.

Abstract: A Quasi-Cyclic, LDPC, large girth, soft-decision decoder and accompanying methods.

Abstract: Structures and methods of generating 8-QAM signals through the effect of a cascaded I/Q modulator and Mach-Zhender modulator. The 8-QAM signals are generated by applying one binary sequence to the dual-drive Mach-Zehnder modulator (MZM) and two binary sequences to the I/Q modulator. Operationally, the I/Q modulator generates QPSK constellation(s), while the dual drive MZM either maintains the QPSK constellation at an out ring, or attenuates its amplitude to the inner ring and rotates its phase by ?/4 phase depending on the binary data it was driven by.

Abstract: A method for optimal combined 2R/3R regenerators placement for optical transmission includes determining an optimal placement of multiple 2R and 3R regenerators that minimizes bit error rate BER at a destination node, determining an optimal number of the 2R and 3R regenerators that minimizes a total cost while satisfying the BER at the destination node, and determining an optimal placement of the 2R and 3R regenerators along a route in the optical transmission.

Abstract: Methods and systems for generating software analysis test inputs include generating a path query to cover a target branch of a program by executing a symbolic test driver concretely and partially symbolically, where at least one symbolic expression is partially concretized with concrete values; determining whether it is feasible to execute the target branch based on whether the generated path query is satisfiable or unsatisfiable using a constraint solver; if the target branch is feasible, generating a new test driver by replacing symbolic values in the symbolic test driver with generated solution values; and if the target branch is not feasible, analyzing an unsatisfiable core to determine whether unsatisfiability is due to a concretization performed during generation of the path query.

Abstract: Systems and methods for data transport, comprising encoding one or more streams of input data using nonbinary low density parity check (NB-LDPC) encoders, corresponding to orthogonal polarization states. Receiving one or more streams of input data using a buffer coupled to the encoders, the data written to the buffer bR bits at a time, where R is the code rate. Generating one or more signals using a 2b-ary mapper implemented as a look-up table (LUT) to store coordinates of a corresponding signal constellation, the 2b-ary mapper configured to assign bits of one or more signals to a signal constellation and to associate the bits of the signals with signal constellation points, wherein the constellation is expanded to avoid bandwidth expansion due to coding, generating substantial net coding gains within a same bandwidth. Modulating nonbinary LDPC-coded data streams using in-phase/quadrature (I/Q) modulators and multiplexing the data streams using polarization beam combiner.

Abstract: A method implemented in a transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal is disclosed. The method comprises splitting data into two or more data streams, inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding, and multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output. Other methods, apparatuses, and systems also are disclosed.

Abstract: Systems and methods for data transport, comprising encoding one or more streams of input data with one or more low density parity check (LDPC) encoders, corresponding to one or more polarization/spatial mode branches. One or more encoded data streams are mapped to symbols, wherein the mapper is configured to assign bits of the symbols to a signal constellation and to associate the bits of the symbols with signal constellation points. A signal constellation is formulated which minimizes a mean-square error of the signal constellation representing the source. The optimum signal constellation size is adjusted to improve transmission quality by adjusting the signal constellation an optical signal to noise ratio (OSNR), wherein the signal constellation is selected using a look-up table (LUT); and the symbols are modulated in accordance with the output of the mapper onto a transmission medium.

Abstract: A method for migration from a multitenant database is shown that includes building an analytical model for each of a set of migration methods based on database characteristics; predicting performance of the set of migration methods using the respective analytical model with respect to tenant service level agreements (SLAs) and current and predicted tenant workloads, where the prediction includes a migration speed and an SLA violation severity; and selecting a best migration method from the set of migration methods according to the respective predicted migration speeds and SLA violation severities.

Abstract: Methods and systems for database migration from a multitenant database include taking a snapshot of an original database to be migrated with a hot backup process, such that the database is still capable of answering queries during the hot backup process; maintaining a query log of all queries to the tenant database after the hot backup process begins; initializing a new database at a target server using the snapshot; replaying the query log synchronize the new database with the original database; and answering new queries with the new database and not the original database.

Abstract: A method sets certain downstream traffic scheduling rules at an optical line terminal OLT and certain sleep control rules at optical network units ONUs. Both downstream traffic scheduling rules and sleep control rules are common information owned by both the OLT and ONUs. The method sets the traffic scheduling rules that each ONU is allocated with some time slots every cycle if the ONU has downstream traffic. Rather than using a control message to notify ONUs with their queue status, the method lets ONUs infer whether its downstream queue is empty or not based on downstream traffic scheduling and lets the OLT infer the status of an ONU based on sleep control rules.

Abstract: A method for nonlinearity compensation for an optical transmission link includes determining a dispersion effect of a transmission link; applying a phase conjugation to the transmission link, the phase conjugation responsive to an input wave over the transmission link and providing a conjugated version of the input wave; and configuring an optimum equivalent link responsive to the phase conjugation after the transmission link to compensate for a non-linear dispersion effect from said transmission link

Abstract: A method implemented in a wireless network including a first base station and a second base station is disclosed. The method includes, upon a change in a load condition, transmitting from the second base station to the first base station load information through backhaul in order to coordinate the first base station and the second base station, allocating, to the second base station, one or more tiles corresponding to one or more time-frequency resource blocks of orthogonal frequency division multiple access (OFDMA), and allocating remaining tiles to the first base station. Other methods and apparatuses are also disclosed.

Abstract: Methods and systems for reusing macro cell resources in femto cell base stations or relay stations in a non-collaborative manner are disclosed. In addition, orthogonal resource allocation between a macro cell base station and femto cell base stations/relay stations may be dynamically adjusted by considering user-population variance. Moreover, an additional level of spatial reuse by femto cell base stations or relay stations can be provided by employing macro cell user location information.

Abstract: Methods and systems for optimizing the utilities of receiver devices in a wireless communication network are disclosed. Precoder design formulations that maximize a minimum worst-case rate or a worst-case sum rate are described for both full base station cooperation and limited base station cooperation scenarios. In addition, optimal equalizers are also selected to optimize the worst-case sum rate.