Abstract: A method estimates a channel impulse response in an ultra wide bandwidth (UWB) system. Multiple training sequences modulated at a chip rate are received. Each training sequence is sampled by parallel with multiple correlators at sampling rate substantially slower than the chip rate to obtain a samples over a time interval of the impulse response at a resolution substantially equal to the chip rate, and then estimating the channel impulse response from these samples.

Abstract: A method allocates resources of a wireless communications network to traffic transmitted to user equipment over a channel of the network. A packet of the traffic to be stored in a selected queue is received. A maximum delay of the selected queue is determined, along with a start time, a finish time, and a queuing order. The packet is inserted in the selected queue according to the start time, the finish time and the queuing order, and then a weight of the selected queue is updated. Then, a next packet to be dequeued from the selected queue is scheduled, and the next packet is transmitted to the user equipment over the channel.

Abstract: A rake receiver detects a transmitted ultra wide bandwidth radio signal. The receiver includes a front end for converting a received version of the transmitted radio signal into an electrical signal. Multiple rake fingers process the electrical signal in parallel. Each rake finger includes the following components that can be connected serially in an arbitrary order. A programmable pulse generator generates a sequence of pulses. A multiplier connected to an output of the front end and to an output of a programmable pulse generator generates a signal functionally related to a product of the output of the front end and the output of the programmable pulse generator. A low-pass filter to filter an output of the multiplier, and an adjustable weight block scale an output of the low-pass filter.

Abstract: A method eliminates spectral lines in a time hopping ultra wide bandwidth signal. First, a train of pulses is generated. The pulses are then modulated in time according to symbols. A polarity of the pulses is inverted randomly before transmitting the pulses as an ultra wide bandwidth signal.

Abstract: A system and method reduce power consumption in a multi-hop wireless communications network. A signal is received from a source node in an intermediate node. The signal includes a request to relay a message to a destination node. The request includes information on power requirements to relay the message either in a relay mode or a regeneration mode. If the available power at the intermediate node exceeds the power requirements, then the request is accepted. Either the relay mode or the regeneration mode is selected, based on criteria for retransmitting the message, and the message is then relayed to the destination node using the selected mode.

Abstract: A personal identification device for use with a mobile telephone in a wireless communications network includes an connector mated to a connector of the mobile telephone normally used for a hands-free kit or a data port. In a typical application, a user of the mobile telephone calls a server. The server sends a first telephone signal to the personal identification device. The device responds with a second telephone signal, designed to simulate voice or data activity, depending on the type of connector that is used. The simulated voice activity is structured in such a way as to cause the radio signal transmitted by the mobile telephone to go on and off in response to the simulated voice activity. A nearby receiver can detect the on/off pattern. The on/off pattern is designed to convey a unique identification code.

Abstract: A method equalizes a received signal in an optical communications system. The received signal is passed through an analog delay line where it is tapped to generate a set of delayed copies of the received signal. In a set of analog multipliers, each delayed copy of the received signal is multiplied by a corresponding weight to generate a set of weighted signals that are then summed to produce an output signal. The output signal is thresholded and subtracted from the output signal to produce an error signal, which is periodically sampled. In a digital weight updating circuit, the weights are produced from digitized versions of the sampled error signal and samples of the delayed copies of the received signal.

Abstract: A multi-path interference canceller cancels interference in a signal received by a receiver in a wideband CDMA communications system. A first stage of the canceller has as input the received signal. Each next stage has as input a delayed version of the input of the previous stage. Each stage includes a first channel estimation and interference generation unit for estimating interference in high-speed signal components of the input signal, and a second channel estimation and interference generation unit for estimating interference in low-speed signal components of the input signal. The interference estimated in the previous stage by the first and second channel estimation and interference generation units is then removed from the input signal of the next stage.

Abstract: In a multiple-input/multiple-output wireless communications system, a stream of data symbols is demultiplexed into M sub-streams, where M is greater than one. Each sub-stream is space-time transmit diversity encoded into a pair of transmit signals. Power is dynamically allocated to each transmit signal according to corresponding feedback signal received from a receiver of the transmit signal.

Abstract: A method transmits data streams in a multiple-input/multiple-output (MIMO) wireless communication systems, where the number of receiving antennas q is less than a number of the transmitting antennas p. The data streams are precoded with a set of finite impulse response filters according to a transfer function of the MIMO channels. The precoded data streams are transmitted over multiple-input/multiple-output channels to a receiver, where the transmitted precoded data stream are detected and decoded to perfectly recover the plurality of data streams without the use of an equalizer.

Abstract: A receiver in a multiple-input-multiple-output, frequency-selective fading wireless communication systems sequentially recovers multiple data stream. A next input stream, having a highest signal-to-noise ratio is selected. The selected input stream is equalized, detected and decoded. The decoded data stream is then substracted from the data streams, and the selecting, equalizing, detecting and decoding, and subtracting is repeated until all of the data streams have been decoded.

Abstract: A method cancels interference in a radio signal received in a receiver of a wireless communications network, such as a cellular telephone network. The interfering signals are serially detected, demodulated and decoded. Each of the decoded signals is then regenerated into its analog form and subtracted from the radio signal until a desired signal is recovered.

Abstract: A method and system for equalizing a signal transmitted via a channel of a communications system stores an input signal received via the channel in a main buffer. A training signal portion of the received input signal is stored in a circular buffer as a circulating training signal. A mean square error of the training signal is minimized while estimating the transmitted signal, until the mean square error is less than a predetermine threshold. In this case, the input signal received via the channel is equalized directly to make decisions on symbols of the signal transmitted via the channel. During an initial stage of training, the mean square error is determined directly from the training signal, during subsequent stages of training the circulating training signal is used.

Abstract: A system and method detect symbols of a modulated signal received via a plurality of channels of a wireless communications system. A symbol transmitted via the channels is initially estimated based on the channel estimate from either pilot symbol or previously estimated symbol, and then channel estimate is updated. The next estimate of the symbol is computed by using updated channel information and maximizing the expectation of the log likelihood function. The next estimate is then quantized according to the signal constellation. The quantized estimate of the symbol is compared with the previous estimate of the symbol to determine if the previous estimate of the symbol and the quantized next estimate of the symbol have converged. Otherwise, the quantized next estimate of the symbol is made as the input for the next iteration, and the updating, optimizing, quantizing, and comparing are repeated until the estimate converges.

Abstract: A method for communicating a bit stream using turbo coding encodes each input bit in the bitstream using a single ⅓ rate turbo encoder to produce a set of three bits. One of the three bits in each set is repeated to produce a set of four bits for each input bit. A time interval between the four bits is increased before transmitting the set of four bits on a communications channel. In a receiver, the time interval between the set of four bits received via the communications channel is decreased using a de-interleaver. The received set of four bits are diversity combine into a received set of three bits, and then a single ⅓ rate turbo decoder is used to recover an output bit for each input bit.

Abstract: A source signal transmitted through multiple channels having space, time and frequency diversities to generate multiple received signals is recovered by an iterative associative memory model with dynamic maximum likelihood estimation. A current symbol vector representing the multiple received signals is projected to a net-vector using a linear matrix operation with a weight matrix W. The weight matrix is obtained by a singular value decomposition of an input symbol sequence. The net-vector is mapped to a nearest symbol vector using a non-linear operation with an activation function The projecting and converting steps are repeated until the nearest symbol vector converges to a valid symbol vector representing the source signal.