Patent application number | Description | Published |
20120163433 | Method for Reducing Interference in Multi-Cell Multi-User Wireless Networks - This invention provides a method for exploiting precoder optimization gains and multi-user diversity gains with interference alignment in general MIMO wireless networks including multiple users. Specifically, two embodiments exploit either a gradient-based search or iteratively orthogonalizing inference. The method can achieve near-optimal performance at a low complexity. Furthermore, a scheduling criterion is provided for wireless networks comprised of a large number of mobile stations in each cell. The criterion can be done independently in each cell to significantly reduce information exchanged between base stations in different cells compared to the methods that perform joint scheduling over all cells. The two embodiments can be utilized in a spectrally efficient communications network equipped with relaying nodes. | 06-28-2012 |
20120183020 | Non-Coherent Space-Time Trellis-Coded Modulations for Network-Coded Wireless Relay Communications - This invention provides a method for jointly optimizing network coding, channel coding, and signal constellations in non-coherent wireless multiple-input multiple-output (MIMO) wireless relay networks for the case when transceivers cannot obtain any knowledge of channel state information (CSI) due to high-speed mobility of the transceivers. In the relay networks, two terminal transceivers simultaneously transmit data to an intermediate relaying transceiver, which in turn broadcasts mixed data using physical-layer network coding to both terminals. The embodiments of this invention exploit different blind space-time trellis-coded modulations (ST-TCM) for each user, whose codebook is jointly generated over a Grassmannian manifold. The method is provided by exponential mapping with affine-lattice convolution for joint optimization of channel coding, modulations, and network coding. The method is designed for fast fading channels with and without interleaving. The method significantly improves performance in non-coherent bidirectional relaying MIMO networks. | 07-19-2012 |
20120201320 | Sparse Channel Estimation Using Order Extension for Frequency and Time Selective MIMO Wireless Communication Networks - A channel matrix is estimated for a channel subject to frequency and time selective fading in a multiple-input multiple-output (MIMO) wireless communication network. The method uses a recursive least-squares (RLS) process and an expectation-maximization (EM) process, based on a L | 08-09-2012 |
20120263454 | Crosstalk-Free High-Dimensional Constellations for Dual-Polarized Nonlinear Fiber-Optic Communications - A method reduces time-varying polarization crosstalk due to XPolM by transmitting multi-dimensional orthogonal constellations. Three variants of crosstalk-free constellations are provided: Grassmann constellations, unitary constellations, and rotation codes. The method uses the Grassmann constellations and the unitary constellations to deal with fiber nonlinearity by applying as a polarization-time coding. The rotation codes exploit a fiber channel characteristic to improve performance and to reduce computational complexity. The underlying orthogonality behind those constellations enables the receiver to decode it as if there is no polarization crosstalk. Moreover, the required computational complexity at the receiver is significantly reduced because neither crosstalk cancellers nor channel estimators are needed. | 10-18-2012 |
20120263464 | Adaptive Cross-Polarization Modulation Cancellers for Coherent Optical Communication Systems - For coherent fiber optic communications, the nonlinear XPolM impairment is the most important issue to realize over-100 Gbps high-speed transmissions. A method provides a way to cancel time-varying XPolM crosstalk by introducing multi-stage adaptive mechanism. In the method, a low-complexity adaptive filtering based on recursive least-squares (RLS) first tracks the time-varying crosstalk along with the per-survivor trellis-state decoding. The estimated channel and the decoded data are then used to calculate the empirical covariance, which is in turn exploited to obtain more accurate channel estimates by means of optimal-weighted least-squares. This is performed with a low-complexity processing over frequency domain with fast Fourier transform. The performance is significantly improved with turbo principle decoding, more specifically, iterative decoding and iterative estimation over a block. | 10-18-2012 |
20130170842 | Method and System for Equalization and Decoding Received Signals Based on High-Order Statistics in Optical Communication Networks - A method equalizes and decodes a received signal including a sequence of symbols. Subsequences of the signal are selected, wherein the subsequences are overlapping and time shifted. For each subsequence, statistics of the channel corresponding to a pattern in the subsequence are selected, wherein the statistics include high-order statistics. A transmitted signal corresponding to the received signal is then estimated based on the statistics. | 07-04-2013 |
20130308700 | Method and System for Communicating Multimedia Using Reconfigurable Rateless Codes and Decoding In-Process Status Feedback - A method and system use capacity-approaching rateless code to communicate multimedia data even with very short codewords, such as 64 bits or less, via erasure and noise channels. The method provides a way to design the edge degree distribution of rateless codes for any arbitrary channel. Based on an equivalent metric of decoding behavior in any channels, the degree distribution of a rateless code such as Luby-transform codes and raptor codes is optimized based on in-process status of decoding. A regularized least-squares optimization is used to avoid erroneous decoding. Multiple feedbacks can further improve the performance. | 11-21-2013 |
Patent application number | Description | Published |
20140314367 | Compound Optical Combiner - A compound optical combiner for combining multiple optical signals includes a set of combiners. The set of combiners includes at least one polarization combiner optically connected to at least one non-polarization combiner. The non-polarization combiner combines a first set of input signals while preserving a polarization of each input signal in the first set of signals. The polarization combiner combines a second set of input signals while converting the polarization of at least one input signal in the second set of signals. | 10-23-2014 |
20140376925 | Method and System for Modulating Optical Signals as High-Dimensional Lattice Constellation Points to Increase Tolerance to Noise - A method modulates data for optical communication by first encoding the data using a forward error correction (FEC) encoder to produce encoded data, which are encoded using a block encoder to produce block encoded data such that Hamming distances between code words that represent the block encoded data are increased. The block encoded data are mapped to produce mapped data such that Euclidian distances between the constellation points are increased. Then, the mapped data are modulated in a transmitter to a modulated signal for an optical channel. | 12-25-2014 |
20150086158 | Multi-Mode Phase-Shifting Interference Device - A multi-mode interference (MMI) device includes a substrate layer, a core layer deposited on the substrate layer for propagating an optical signal, and a cladding layer deposited on the core layer for guiding the optical signal. The core layer includes a core section suitable for propagating multiple optical signals having different wavelengths. The core section includes a shifting segment for uniquely shifting phases of the multiple optical signals. The shifting segment includes at least one or a combination of sections having different effective refractive index, a tilted segment, a curved section, and waveguides with variations in width, thickness or effective refractive index. | 03-26-2015 |