Nortel Networks Corporation

Blackberry Corporation

Eaton Intelligent Power Limited

Cooper Technologies Company

Research in Motion Corporation

Sergey Sukhobok

Aleksandar Purkovic

Nina K Burns

Michael Livshitz

Muhammad Chaudhry

Roger Kirk Alexander

Jianming Yuan

Tzeta Tsao

Steven Baigal

Shravan Rangaraju

Shashikant Chowdhary

Sharif M Redwan Siddiqui

Roger K Alexander

A method for constructing a low-density parity-check (LDPC) code using a structured base parity check matrix with permutation matrix, pseudo-permutation matrix, or zero matrix as constituent sub-matrices; and expanding the structured base parity check matrix into an expanded parity check matrix. A method for constructing a LDPC code using a structured base parity check matrix H=[H|H], His the data portion, and His the parity portion of the parity check matrix; the parity portion of the structured base parity check matrix is such so that when expanded, an inverse of the parity portion of the expanded parity check matrix is sparse; and expanding the structured base parity check matrix into an expanded parity check matrix. A method for encoding variable sized data by using the expanded LDPC code; and applying shortening, puncturing.System and method for operating a wireless device to encode data using low-density parity-check (LDPC) encoding is discussed. One example method includes: computing a number of modulated orthogonal frequency-division multiplexing (OFDM) symbols for transmitting the data; computing a number of shortening bits; distributing the number of shortening bits over the at least one LDPC codeword; computing a number of puncturing bits for the at least one LDPC codeword; distributing the number of puncturing bits over the at least one LDPC codeword; determining a criterion using at least one of the number of shortening bits and the number of puncturing bits; if the criterion is met, increasing the number of modulated OFDM symbols and recalculating the number of puncturing bits; generating the encoded data using the number of shortening bits, the number of puncturing bits, and the at least one LDPC codeword; and transmitting the encoded data.

Structured low-density parity-check (LDPC) code

A method for constructing a low-density parity-check (LDPC) code using a structured base parity check matrix with permutation matrix, pseudo-permutation matrix, or zero matrix as constituent sub-matrices; and expanding the structured base parity check matrix into an expanded parity check matrix. A method for constructing a LDPC code using a structured base parity check matrix H=[H|H], His the data portion, and His the parity portion of the parity check matrix; the parity portion of the structured base parity check matrix is such so that when expanded, an inverse of the parity portion of the expanded parity check matrix is sparse; and expanding the structured base parity check matrix into an expanded parity check matrix. A method for encoding variable sized data by using the expanded LDPC code; and applying shortening, puncturing.

In a self-organizing wireless multihop network, each node device selects operation among short-range (SR) and long-range (LR) communication modes, among which the SR mode uses a higher data rate than the LR mode. Each node device advertises connectivity link availability for neighboring node devices, and selectively initiates a link in response to connectivity availability advertised by at least one neighboring node device. The availability advertising is performed in the SR and the LR communication modes, according to a periodicity that is dynamically-variable in response to prevailing circumstances in the local neighborhood. The link initiation is selectively performed in one of either the SR or the LR communication mode based on selection criteria that include data throughput performance associated with different neighboring node devices with which connectivity is available via a certain communication mode.

Dynamically-selectable multi-modal modulation in wireless multihop networks

Systems and methods for performing predictive frequency searches in ad-hoc multi-hop wireless networks is described herein. In one exemplary embodiment, a predicted frequency is selected and a synchronization request is sent from an initiating node to a target node on the predicted frequency. If the transmitted synchronization request is the last synchronization request for the predictive frequency search mode sequence, then the initiating node enters into a receiving mode to receive a synchronization response message from the target node. If not, the initiating node selects a new predicted frequency, and sends a new synchronization request to the target node on that frequency. This repeats until the transmitted synchronization request is the last predictive synchronization request, and the initiating node enters into the receiving mode. The initiating node in the selection of synchronization request transmission frequencies can adaptively alternate between predictive and full spectrum frequency searches.

Adaptive, predictive synchronization for reducing connection establishment delays in ad-hoc frequency hopping spread spectrum networks

In a wireless multihop network having node devices within communication range neighboring node devices in a corresponding local neighborhood, the node devices generate visibility messages to be transmitted via connection-less broadcast. The visibility messages include at least an identifier of the corresponding node device. Visibility messages received by each of the node devices from the one or more neighboring node devices are processed to determine a measure of density of the local neighborhood. This measure of density also accounts for the heterogeneous transmit power capabilities of node devices and is used for updating of one or more operational parameter of the node device relating to utilization of the radio communications medium by that node device. A degree of utilization of the medium through the control of transmission data rate and power is adjusted based on an inverse relation to the measure of density determined from the received visibility messages.

Informational broadcast messages and its uses in wireless multihop networks

A higher code rate Low-Density Parity Check (LDPC) matrix may be designed by concatenating additional matrices to a &#x3c0;-rotation parity check matrix. The concatenated matrix may be selected such that the resultant LDPC matrix exhibits good expansion characteristics to enable the LDPC matrix to be used with variable block length codes. The codes may be designed by generating an ensemble of available codes, encoding them with information vectors of weightandand discarding codes with a low minimum distance. The approximate upper bounds for the remaining codes are then calculated and a small set of codes with the lowest bound under high signal to noise ratio is selected. The girth distributions for the remaining codes are then calculated and the code that has the minimum number of short cycles is selected. The selected code is concatenated to the original &#x3c0;-rotation parity check matrix.

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Rockville, MD, United States of America

Sergey Sukhobok