Abstract: A mobile system capable of proactively predicting characteristics for optimal communication among mobile nodes comprises a network controller and adaptive predictive mobile nodes. The adaptive predictive mobile nodes contain a position location technology element, a database containing information on factors affecting radio propagation, and a prediction processor. To provide energy efficient power control and routing for a communication, the adaptive predictive mobile node determines its current and predicted future position and the current and future predicted positions of other nodes in the network. Based on the information obtained, the adaptive predictive node executes a set of prediction capabilities in the prediction processor. After executing these capabilities, the adaptive predictive node identifies the advantaged location, power level, transmission parameters, communication time and route for communications between nodes.

Abstract: An apparatus and method for reducing interference between an uplink transmitter of a space-based wireless communication system and an uplink or downlink receiver of a terrestrial wireless communication system are described. The space-based system may be a Fixed Satellite Service (FSS) system and the terrestrial system may be a Local Multipoint Distribution Service (LMDS) system. An ordered list of preferred uplink transmission frequencies is assigned to all FSS uplinks located in a particular cell of the LMDS system. Different ordered lists are used in different cells of the LMDS system, while uplinks located in the same cell can utilize the same ordered list. A given potentially-interfering uplink transmitter selects an uplink transmission frequency from the appropriate ordered list if the uplink is unable to operate outside the LMDS frequency band and there are no gaps in the LMDS spectrum which can accommodate the uplink transmission.

Abstract: In a TDM/TDMA portable radio communications system, a portable handset is compatible for operation in both a frequency-division duplexing (FDD) mode for communication in the licensed portion of the Emerging Technologies frequency band, and in a time-division duplexing (TDD) mode for communication in the unlicensed portion of the Emerging Technologies frequency band. In the FDD mode, different frequencies are used to separate a downlink transmission to a portable from a port from an uplink transmission from a port to a portable. In the TDD mode, uplink and downlink transmissions are separated in different time-slots, but at the same frequency. The handset includes common transmit and receive circuitry that operates at fixed IF frequencies that are separated in frequency by the fixed FDD frequency difference between corresponding uplink and downlink signals.

Abstract: A system for spectrum sharing between a point-to-point microwave system and a TDM/TDMA wireless communications system in a common geographical area is described. Each transmitter/receiver in the point-to-point microwave system transmits, in addition to its normal information signal, a beacon signal which is uniquely associated with the receiver receive frequency. In selecting uplink and downlink frequencies for port assignment, each port monitors the beacon frequencies and selects as uplink and downlink frequencies, frequencies which associated beacons fall below a predetermined threshold. Similarly, before accessing the wireless communications system through a selected port, a portable monitors the beacons associated with the selected port's uplink frequency. If the beacon associated with the uplink frequency exceeds a threshold, the portable selects an alternate port through which to access the network.

Abstract: A system for spectrum sharing between a point-to-point microwave system and a TDM/TDMA wireless communications system in a common geographical area is described. Each transmitter/receiver in the point-to-point microwave system transmits, in addition to its normal information signal, a beacon signal which is uniquely associated with the receiver receive frequency. In selecting uplink and downlink frequencies for port assignment, each port monitors the beacon frequencies and selects as uplink and downlink frequencies, frequencies which associated beacons fall below a predetermined threshold. Similarly, before accessing the wireless communications system through a selected port, a portable monitors the beacons associated with the selected port's uplink frequency. If the beacon associated with the uplink frequency exceeds a threshold, the portable selects an alternate port through which to access the network.

Abstract: A receiver for use in the port or portable units in a TDM/TDMA digital radio communications system is disclosed which incorporates an equalizer (107) to compensate for channel distortion due to multipath delay spread. Each received burst of information is oversampled at a multiple of the symbol rate and stored in a buffer memory (105). A joint estimator (106) processes the stored burst by operating on a known training sequence of bits within the burst to determine burst timing (where the burst actually begins) and the symbol timing (the optimum sample sample per oversampled symbol to be used for detection purposes). The estimator also determines whether the stored burst should be processed in a time-forward or time-reversed order.

Abstract: Digital circuitry comprising multiple read-only-memory (ROM) units that store predetermined data sequences are utilized to generate a digital representation of a composite signal that represents overlapping Nyquist pulses derived from input data bits. The generated signal exhibits relatively fast ON/OFF transitions. At the same time, control signals applied to the outputs of the ROMs insure that the representation preserves prespecified tail portions that minimize spectral spreading in a time-division multiple-access (TDMA) system. Once version of the circuitry generates a digital representation of a baseband signal derived from a single stream of input data bits. Another version of the circuitry generates a digital representation of a quadrature-phase-modulated carrier derived from two independent input data streams.

Abstract: A receiver for use in the port or portable units in a TDM/TDMA digital radio communications system is disclosed which incorporates an equalizer (107) to compensate for channel distortion due to multipath delay spread. Each received burst of information is oversampled at a multiple of the symbol rate and stored in a buffer memory (105). A joint estimator (106) processes the stored burst by operating on a known training sequence of bits within the burst to determine burst timing (where the burst actually begins) and the symbol timing (the optimum sample per oversampled symbol to be used for detection purposes). The estimator also determines whether the stored burst should be processed in a time-forward or time-reversed order.

Abstract: In order to correctly demodulate a received sequential burst of symbols in a Time Division Multiple Access (TDMA) radio system, proper symbol timing is necessary. A method and circuitry for estimating symbol timing is disclosed in which the IF radio signal is sampled and digitized at a sampling rate which is sixteen times the symbol rate. The digitized samples are processed to obtain phase values. A one symbol delay is introduced and differential phase values derived, a differential phase value being derived for each of the sixteen sampling times per symbol. The differential phase values are compared with expected differential phase values and the absolute differences are accumulated for each sampling time over substantially the entire burst. The symbol timing is selected to be the particular one-of-the-sixteen sampling times that results in the minimum sum of differences.

Abstract: The present invention relates to a transmitter and a receiver for use in a digital communication system which are capable of transmitting and receiving, respectively, a single duplex analog signal channel, such as, for example, a voice channel, and limited short asynchronous data bursts. The transmitter portion includes an encoding means which uses an adaptive companding algorithm in the encoding process while the receiver portion includes a decoding means using the same synchronized algorithm in the decoding process. The transmitter and receiver at each end of a communication channel also include a signaling interface which can interrupt the coding and decoding process to transmit and receive, respectively, an occasional data burst without upsetting the synchronization of the adaptive companding algorithm states at both ends of the channel.

Abstract: In a multibeam digital time-division switched satellite communications system users of differing capacity needs are efficiently served by quantizing the capacity of each ground station and similarly the bit repetition rate of each ground station into integral powers of 2. At the satellite the uplink bitstream transmitted by each ground station is recovered and the higher rate bitstreams are demultiplexed to form plural equal bit rate subchannels at the input to the satellite switch, the number of subchannels formed being equal to the quantized capacity of the associated ground station. After the satellite switch transfers the bits present at the switch inputs from all ground stations to the appropriate switch outputs, a plurality of output subchannels are multiplexed to form the higher bit rate signals, the number of subchannels multiplexed being equal to the quantized capacity of the ground station to which the bits are directed.

Abstract: The present invention relates to a multibeam, digitally modulated, time division switched communication system especially for use with a satellite repeater wherein separate up-link and down-link signals are transmitted between each of a plurality of ground station areas and the repeater using space diversity techniques. The frequency band of each up-link signal is split to include at least two frequency multiplexed channels, each channel being separated at the repeater and independently switched at baseband frequencies through a repeater switching network comprising at least two matrix switches for retransmission on the appropriate down-link signal.