Abstract: A method discovers routes for forwarding packets from source nodes (sources) to sink nodes (sinks) in a wireless network, wherein some neighboring sources act as relay nodes. Each source measures a rate of receiving control messages from each neighboring node. Then, the data packets are forwarded from a particular source to the sink via the neighboring nodes having a lowest rate.

Abstract: A wireless network includes a set of nodes. Each node includes a transmitter and a receiver. A block of data bits is converted to a block of data symbols. The block of data symbols is partitioning timewise into groups of data symbols. A set of subcarriers is assigned to each group of data symbols, and each group of data symbols is spread to a chip sequence using a coding block of spreading sequences, wherein the spreading sequences are based on types of the groups of data symbols. Then, after the spreading, the chips are transmitted as orthogonal frequency-division multiplexing (OFDM) data symbols on the assigned subcarriers.

Abstract: A signal received via a fading channel is decoded in radio frequency receiver by first demodulating the signal to a baseband signal, and serial to parallel converting the baseband signal to a precoded signal. Then, a channel matrix is estimated from the precoded signal, and symbols are detected in the precoded signal using the channel matrix. The decoding uses probabilistic data association. The detecting initializes a probability distribution for each symbol, and selects an ordering in which to update the probability distributions. The probability distribution for each symbol are updated according to the ordering, until a termination condition is reached, and then demapped and parallel to serial converted to estimate a sequence of bits used to generate the signal.

Abstract: In optical networks new links are added between nodes over time to satisfy the increasing traffic demands of the network. Existing links are normally not changed, resulting in a network that does not have the lowest energy consumption. A method provides a way to reduce the energy consumption of the overall network while supporting the required traffic demands at all times. The network includes a multiple source nodes, and multiple destination nodes. The network is represented by a graph of nodes connected by edges, wherein each node represents an optical network element and each edge represents a path connecting two optical network elements. Each edge is labeled with a demand. The non-bridge edge with a lowest demand is removed from the graph, and the lowest demand is added to the non-bridge edge with a highest demand. These steps are repeated until a termination condition is reached.

Abstract: Interference in a wireless network is detected by first applying during a detection stage a two-sample Kolmogorov-Smirnov (KS) test to samples obtained from a channel in the wireless network to obtain a KS statistic. When the KS statistic is larger than a predetermine threshold, it is determined that the samples include narrowband interference, and wideband otherwise.

Abstract: Nodes in a network are clustered by first determining, in each node, a cluster head capability (CHC). The CHC is broadcasting, directly or indirectly, until all nodes have received the CHCs. Each node nominates, one or more candidate cluster heads based on the CHCs, and then, in each node, at least one cluster head is selected from the candidate cluster head nodes based on maximal CHCs.

Abstract: A location of a smartkey is determined by first determining coordinates of a set of candidate vertices of an array of receive antennas at a receiver based on maximal magnetic field voltages in the receive antennas due transmitting a radio signal (RF) by the smartkey. A set of candidate locations of the transmitter is determined based on the coordinate of the set of vertices. A set of final candidate locations is determined based on a predetermined threshold of the voltages. The final candidate locations are then combined to determine the location of the smartkey.

Abstract: A signal received via a fading channel is decoded in radio frequency receiver by first demodulating the signal to a baseband signal, and serial to parallel converting the baseband signal to a precoded signal. Then, a channel matrix is estimated from the precoded signal, and symbols are detected in the precoded signal using the channel matrix. The decoding uses probabilistic data association. The detecting initializes a probability distribution for each symbol, and selects an ordering in which to update the probability distributions. The probability distribution for each symbol are updated according to the ordering, until a termination condition is reached, and then demapped and parallel to serial converted to estimate a sequence of bits used to generate the signal.

Abstract: Interference in a received orthogonal frequency division multiplexing (OFDM) symbol, modulated according to selected constellation points sk, is reduced. The symbol includes a set of pilot signals and a set of data signals yk, where k is a number of consecutive subcarriers used for the pilot and the data signals. The pilot signals are thresholded to detect interfering pilot signals, which are then erased. Channels ?k are estimated using remaining pilot signals. The set of data signals are decoded based on the estimated channels ?k, and, for each bit bi in the set of data signals, a logarithmic likely ratio (LLR) log ? ? s k : b i = 0 ? 1 ? y k - H ^ k ? s k ? 2 ? s k : b i = 1 ? 1 ? y k - H ^ k ? s k ? 2 is determined. The LLR is an indicator of the likely interference.

Abstract: Broken links in a sensor network are avoided by representing the network as a DODAG. A rank associated with each node defines a position of each node relative to other nodes, and the rank is in a form of a proper fraction, and the rank of each node never increases to enable loop-free routing.

Abstract: A network includes a transmitter and a receiver, wherein the transmitter includes a set of transmit antennas and the receiver includes a set of receive antennas. The transmitter duplicates a packet as copies of the packet, and selects subsets of the set of transmit antennas independent of channel characteristics between the subsets of transmit antennas and the set of receive antennas, wherein combinations of the antennas in the subsets of the transmit antennas are different. The receiver selects subsets of the set of receive antennas independent of channel characteristics between the subsets of receive antennas and the set of transmit antennas, wherein combinations of the antennas in the subsets of the receive antennas are different. The selected subsets are used to transmit the packet, and retransmit the packet in case of a failure in a previous transmission.

Abstract: Signal received in a wireless network are detected by arranging samples of the signal in a set of windows. For each window, estimating interference, an average signal, noise and interference ratio (SINR), and a channel. For each window, also classifying a type of a process of a set of processes of a receiver. Then, selecting the process for each windows according to the type to detect the signal in the window.

Abstract: An operation channel in a multi-hop network is determined. The network uses a set of channels, and one of the nodes is a network management node. The operation channel is selected in the network management node. Then, the network management node broadcasts a channel information packet including the operation channel using all channels. The channel information packet is received in each of other nodes, either directly from the network management node or from an intermediate node that received and rebroadcasted the channel information packet. Lastly, the operation channel in each node is set according to the channel information packet until the network is formed.

Abstract: 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.

Abstract: Packets are transmitted by a server to mobile nodes in a coverage area of a wireless network using a coverage and reliability map, which indicates qualities and reliabilities of links between the server and the nodes. When a new packet is received in the server, the server transmits the packet if a current load of the packets including the new packet is less than a peak load constraint. Otherwise, the new packet is delayed for one time slot.

Abstract: Packets are transmitted by a server to mobile nodes in a coverage area of a wireless network using a coverage and reliability map, which indicates qualities and reliabilities of links between the server and the nodes. When a new packet is received in the server, the server transmits the packet if a current load of the packets including the new packet is less than a peak load constraint. Otherwise, the new packet is delayed for one time slot. Packets are transmitted according to associated priorities.

Abstract: An operation channel in a multi-hop network is determined. The network uses a set of channels, and one of the nodes is a network management node. The operation channel is selected in the network management node. Then, the network management node broadcasts a channel information packet including the operation channel using all channels. The channel information packet is received in each of other nodes, either directly from the network management node or from an intermediate node that received and rebroadcasted the channel information packet. Lastly, the operation channel in each node is set according to the channel information packet until the network is formed.

Abstract: Broken links in a sensor network are avoided by representing the network as a DODAG. A rank associated with each node defines a position of each node relative to other nodes, and the rank is in a form of a proper fraction, and the rank of each node never increases to enable loop-free routing.

Abstract: A set of routes are discovered in a network including concentrators, smart meters and an imaginary node. Each concentrator node, a source, broadcasts a route request (RREQ) packet to the imaginary destination node. Intermediate nodes store a route as a node list (NL) in the RREQ packet and as a route table (RT) in the node. Then, each smart meter node can select a primary route and a secondary route from the smart meter node to any concentrator from the route table.

Abstract: A method estimates the time-of-arrival (ToA) of signals received via multipath channels. The received signal of a number of trials is first passed through a band-pass filter and then sampled. The presence of a channel tap within a time window is estimated by comparing a threshold to a largest eigenvalue of the covariance matrix of a time window. The signal samples are used to calculated a band region of a complete covariance matrix. After the band region has been updated for all signal samples, the covariance matrices for a moving window can be extracted from the band region. The ToA is estimated as the ending time of the leading window, which is the earliest window, such that the largest eigenvalue is larger than a given threshold.