Abstract: A system and method for transmitting a plurality of spread-spectrum signals over a communications channel having fading. The plurality of spread-spectrum signals are radiated by a plurality of antennas, with each antenna preferably spaced by one-quarter wavelength. A plurality of receiver antennas receive the plurality of spread-spectrum signals and a plurality of fading spread-spectrum signals. Each receiver antenna is coupled to a plurality of matched filters having a respective plurality of impulse responses matched to the chip-sequence signals of the plurality of spread-spectrum signals. A RAKE and space-diversity combiner combines, for each respective chip-sequence signal, a respective plurality of detected spread-spectrum signals and a respective multiplicity of detected-multipath-spread-spectrum signals, to generate a plurality of combined signals. The symbol amplitudes can be measured and erasure decoding employed to improve performance.

Abstract: An improvement to a spread-spectrum receiver at a bse station having a matched filter. A symbol sampler samples at the symbol time Ts, a symbol sample from the matched filter. A noise sampler samples at a plurality of chip times kTc, but not at the symbol time Ts, a plurality of noise samples from the matched filter. An estimator or low-pass filter filters the plurality of noise samples from the symbol sampler, to generate a noise estimate. A combiner circuit subtracts the noise estimate from the low-pass filter from the symbol sample from the symbol sampler, thereby generating a comparison signal. A magnitude device determines a magnitude of the comparison signal. A comparator has threshold voltage applied to a threshold input. The comparator compares the magnitude of the comparison signal to the threshold voltage, thereby generating the erasure signal. An erasure decoder erasure decodes the input data using the erasure signals from the erasure detector.

Abstract: An improvement to a spread-spectrum base station receiver having a matched filter. A symbol sampler samples at the symbol time TS, a plurality of symbol samples from the matched filter. A relative-signal-level decoder decodes the plurality of received-symbol samples, thereby generating a plurality of decoded-symbol samples. A noise sampler samples at a plurality of chip times kTC, but not at the symbol time TS, a plurality of noise samples from the matched filter, before, after, or a combination of before and after, a symbol sample. An estimator processes the plurality of noise samples. The erasure detector detects for each decoded-symbol sample from the plurality of decoded-symbol samples and from the plurality of noise samples, an erasure condition for the corresponding decoded-symbol sample, and thereby generates an erasure signal. An erasure decoder erasure decodes the input data using the erasure signals from the erasure detector.

Abstract: A high data rate, high processing gain, direct sequence spread spectrum system that transmits a BPSK or QPSK signal. The system FEC encodes and interleaves data which are collected and stored and forwarded N bits at a time by transmitting one of 2N pseudo random waveforms every time N bits are collected. The 2N pseudo random waveforms can be sent as an orthogonal, bi-orthogonal, or nearly orthogonal waveform. During acquisition, a plurality of product devices multiply a received spread-spectrum signal by a header chip-sequence signal. In each case, the header chip-sequence signal has a different delay, with each delay being at most one chip. Acquisition can also be achieved using a matched filter.

Abstract: A spread-spectrum, code-division-multiple-access (CDMA), system with a remote station (RS) communicating with a first base station (BS). The remote station receives the first BS-packet signal, and transmits a first RS-packet signal to the first base station. The first RS-packet signal is spread by a first RS-chip-sequence signal at a second frequency. The first base station receives the first RS-packet signal. The first base station stores and forwards the despread first RS-packet signal to a central office (CO). The remote station monitors control and packet transmission channels of other base stations in geographic proximity to the remote station. Each of the base stations transmit BS-packet signals. The remote station determines, based on signal metrics and available capacity, when to change from the first base station to the second base station. The second base station stores and then forwards the despread second RS-packet signal to the central office.

Abstract: A spread-spectrum system having a transmitted data rate determined by an error rate syndrome at a spread-spectrum receiver. A demultiplexer demultiplexes input data into a plurality of data channels. A plurality of FEC encoders FEC encodes the plurality of data channels, as a plurality of FEC encoded channels. A plurality of spread-spectrum processors spread-spectrum processes the plurality of FEC encoded channels as a plurality of spread-spectrum channels. The plurality of spread-spectrum channels preferably uses a plurality of orthogonal or quasi-orthogonal chip-sequence signals to define a particular spread-spectrum channel. A combiner combines the plurality of spread-spectrum channels as a code-division-multiplexed signal. At a receiver, a plurality of spread-spectrum despreaders despreads the code-division-multiplexed signal into a plurality of despread channels. A multiplicity of adders is electronically controlled by an adder-control signal.

Abstract: An improvement to a spread-spectrum code-division-multiple-access system, using a channel sounding signal from a base station (BS) to provide initial transmitter power levels for remote stations (RS). The base station has a BS-spread-spectrum transmitter for transmitting BS-spread-spectrum signals at a first frequency and a BS-spread-spectrum receiver for receiving RS-spread-spectrum signals at a second frequency. The RS-spread-spectrum signals are transmitted by the remote stations at the second frequency. The BS-spread-spectrum signals at the first frequency are outside the correlation bandwidth of the RS-spread-spectrum signals at the second frequency. The base station has a BS transmitter for transmitting a BS-channel-sounding signal at the same carrier frequency being used by the remote stations to transmit a spread-spectrum signal to the base station. The bandwidth of the BS-channel-sounding signal is much of the bandwidth of the BS-spread-spectrum signal.

Abstract: An improvement for obtaining synchronization to a chip-sequence signal. The chip-sequence signal has a plurality of chips, and is embedded in a spread-spectrum signal. A shift register shifts or cycles a replica or delayed replica of the chip-sequence signal. The shift register has a plurality of taps, which correspond to the plurality of chips. A plurality of comparators compares the chip-sequence signal embedded in the spread-spectrum signal with the replica of the chip-sequence signal stored in the shift register. From the comparison, the plurality of comparators generates, for each tap of the shift register, a plurality of compared values at each comparator of the plurality of comparators. A plurality of counters up and down counts, from each comparator, a respective plurality of compared values. The respective plurality of compared values appears at an output of a respective comparator of the plurality of comparators. The plurality of counters thereby generates a plurality of totals, respectively.

Abstract: A system and method for transmitting a plurality of spread-spectrum signals over a communications channel having fading. The plurality of spread-spectrum signals are radiated by a plurality of antennas, with each antenna preferably spaced by one-quarter wavelength. A plurality of receiver antennas receive the plurality of spread-spectrum signals and a plurality of fading spread-spectrum signals. Each receiver antenna is coupled to a plurality of matched filters having a respective plurality of impulse responses matched to the chip-sequence signals of the plurality of spread-spectrum signals. A RAKE and space-diversity combiner combines, for each respective chip-sequence signal, a respective plurality of detected spread-spectrum signals and a respective multiplicity of detected-multipath-spread-spectrum signals, to generate a plurality of combined signals. The symbol amplitudes can be measured and erasure decoding employed to improve performance.