Abstract: A soft decision output decoder and decoding method. The decoder decodes a sequence of signals output by an encoder and transmitted over a channel. The soft decision output decoder includes a first "generalized" Viterbi decoder for decoding the sequence of signals received over the channel during a forward iteration through a trellis representing the encoder output having a block length T. The first "generalized" Viterbi decoder begins at an initial state t.sub.0 and provides a plurality of forward iteration state metrics .alpha. for each state at each time interval over a window of length 2L, where L is on the order of a few constraint lengths and 2L is less than a block length T. A second "generalized" Viterbi decoder decodes the sequence of signals received over the channel during a backward iteration through the trellis. The second decoder starts at a second time t2L and provides a plurality of backward iteration state metrics .beta. for each state at each time interval.

Abstract: A novel and improved method and apparatus for high rate CDMA wireless communication is described. In accordance with one embodiment of the invention, a set of individually gain adjusted subscriber channels are formed via the use of a set of orthogonal subchannel codes having a small number of PN spreading chips per orthogonal waveform period. Data to be transmitted via one of the transmit channels is low code rate error correction encoded and sequence repeated before being modulated with one of the subchannel codes, gain adjusted, and summed with data modulated using the other subchannel codes. The resulting summed data is modulated using a user long code and a pseudorandom spreading code (PN code) and upconverted for transmission. The use of the short orthogonal codes provides interference suppression while still allowing extensive error correction coding and repetition for time diversity to overcome the Raleigh fading commonly experienced in terrestrial wireless systems.

Abstract: The method and apparatus of the present invention improve the immunity to interference of a radio receiver. The power level of a received signal is detected. If the power level meets or exceeds a predetermined power threshold, the low noise amplifier is by-passed, thus increasing the intercept point of the receiver components.Alternative embodiments include the use of an RF power detector to control the front-end gain as a function of jammer power. In lieu of a switchable RF gain block, several methods of continuous gain control are proposed. Continuous gain control allows the interference suppression and sensitivity of the receiver to be adjusted at lower signal levels than the switchable gain block.

Abstract: A novel and improved method and system for reducing the bandwidth requirements of satellite or wireless communication networks is described. In accordance with one embodiment of the invention, a training sequence is transmitted over a training channel from a terminal to a master station. The master station measures a frequency error of the training sequence, and provides the frequency error to the terminal. The terminal adjusts its transmit frequency by the frequency error, offsetting all further data channel transmissions by the frequency error.

Abstract: A method and apparatus for implementing a vocoder in a application specific integrated circuit (ASIC) is described. The apparatus contains a DSP core that performs computations in accordance with a reduced instruction set (RISC) architecture. The circuit further includes a specifically designed slave processor to the DSP core referred to as the minimization processor. The apparatus further includes a specifically designed block normalization circuitry.

Abstract: A multiple frequency antenna and coupler are disclosed that establish a low noise communication path from a multiple frequency wireless telephone or multiple single frequency telephones, each operating at a different frequency, in a vehicle to the exterior of the vehicle. The coupler includes internal and external elements that are oriented face to face with each other, with a windshield sandwiched between them. Each element is tapered, and the elements are juxtaposed with each other such that the wider end of one element is generally opposite the narrower end of the other. A multiple frequency radiator is attached to the external element. The radiator includes plural radiating elements that are separated from each other and that are attached to a common base, with each radiating element being configured for radiating a respective frequency.

Abstract: A novel and improved method and apparatus for high rate CDMA wireless communication is described. In accordance with one embodiment of the invention, a set of individually gain adjusted subscriber channels are formed via the use of a set of orthogonal subchannel codes having a small number of PN spreading chips per orthogonal waveform period. Data to be transmitted via one of the transmit channels is low code rate error correction encoded and sequence repeated before being modulated with one of the subchannel codes, gain adjusted, and summed with data modulated using the other subchannel codes. The resulting summed data is modulated using a user long code and a pseudorandom spreading code (PN code) and upconverted for transmission. The use of the short orthogonal codes provides interference suppression while still allowing extensive error correction coding and repetition for time diversity to overcome the Raleigh fading commonly experienced in terrestrial wireless systems.

Abstract: In a communications network, a network user communicates using a remote unit with another user via at least one base station. The communications network has a first base station having a first coverage area and a second base station having a second coverage area. In the situation where communication is not established between the second base station and the remote unit, in order to provide communication between the remote unit and the first base station when the remote unit is in the first coverage and simultaneously in the second coverage area, the first base station produces a first active communication signal at intended for the remote unit. The first base station transmits the first active communication signal from a first antenna.

Abstract: An L-shaped assembly fixture is used in connecting cables between components in a housing and a top panel for closing the housing after assembly. A base plate of the fixture has opposite side edges and opposite end edges, and an upright plate is secured along one side edge of the base plate so as to project upwardly in a direction perpendicular to the base plate. The upright plate has an upper edge with a slot extending along the length of the upper edge for supporting a top panel vertically adjacent an open face of a housing which is supported on the base plate.

Abstract: The cellular telephone includes a universal asynchronous receive and transmit (UART) chip for receiving data in a serial format from an external source, such as a laptop computer, and for converting the serial data to parallel bytes of data for transmission to a microcontroller of the cellular telephone. The UART operates in one of two modes: a sample mode and a byte mode. In the sample mode, voltage levels of serial data signals received by the UART are detected and sample bytes are generated representative of those voltage levels. The sample bytes are stored within a receive First In First Out (FIFO) queue of the UART for eventual transference to the microcontroller. The microcontroller converts the sample bytes to signals appropriate for transmission using a cellular transmission format such as code division multiple access (CDMA). In the byte mode, the UART receives data bytes as bytes and stores those bytes directly within the receive FIFO without any sampling.

Abstract: In a communication system capable of variable rate transmission, multi-level scheduling improves utilization of the reverse link and decreases the transmission delay in data communication. Multi-level scheduling comprises base station level scheduling, selector level (system level) scheduling, and network level scheduling. Network level scheduling is performed for base station in soft handoff with base stations which are controlled by different selector scheduler. Selector level scheduling is performed for remote stations in soft handoff with base stations which are controlled by the same selector scheduler. And base station level scheduling is performed for remote stations not in soft handoff. Base station level scheduled is performed using residual capacity after higher level scheduling have been performed. Each scheduling level can have different scheduling interval.

Abstract: A method and apparatus for controlling various functional elements in a digital telephone system using state determination from an echo canceller. An echo canceller is used to evaluate which one of five talk states two speakers are engaged in during a telephone conversation. This state determination information is used to control a tone detector function, a noise suppressor function, an adaptive equalizer function, a transmission mute function, and a vocoder encoder function within a vocoder. During the talk state where the far-end speaker is active and the near-end speaker is inactive, the echo canceller provides a signal which disables background noise estimates from being performed in the noise suppressor and the vocoder encoder. The same signal is used to disable the tone detector and to enable the transmission mute function during this talk state.

Abstract: A system and method for resolving ambiguity in an ambiguous position solution for a user terminal position in a satellite communications system which includes a user terminal, at least one satellite, and a gateway communicating with the user terminal through the satellite. Each satellite has a plurality of satellite beams which each illuminate a region on the Earth in a known pattern relative to a satellite sub-track. A satellite beam illuminating the user terminal is identified along with its corresponding position relative to the sub-track. The orientations of possible user terminal positions and the identified beam relative to the satellite sub-track are compared to each other. Possible user terminal positions falling on an incorrect side of the sub-track from the detected beam illuminating the user terminal, are considered as incorrect solutions for that user terminal.

Abstract: A system and method for reducing radio frequency interference arising in connection with pulsed transmission over time division multiplexed communication channels. In a first embodiment, a subscriber station is nominally assigned all of the slots of each frame of a first transmit channel. By transmitting RF energy substantially continuously, the subscriber station reduces interference arising from pulsed transmission. In a second embodiment, a subscriber station is nominally assigned one or more slots of each frame of a primary channel for conventional transmission of useful information, and is also instructed to continuously transmit RF energy over an auxiliary channel at times other than during the assigned primary channel slots. In this way, interference generated in the vicinity of the subscriber station is reduced due to the substantially continuous transmission of RF energy by the subscriber station.

Abstract: An EMI shielding apparatus has an outer peripheral wall extending around a combined area of predetermined shape and dimensions for enclosing at least two adjacent areas on a printed wiring board to be shielded from one another. A single transverse wall extends between opposing portions of the peripheral wall to divide the combined area into the two adjacent sub-areas to be shielded from one another. The single transverse wall is of single wall thickness, reducing the EMI shield footprint. The peripheral wall and transverse wall may be formed integrally as one frame, or from two or more adjacent sub-frames.

Abstract: In a communications network, a network user communicates using a remote unit with another user via at least one base station. The network is comprised of first and second mobile switching control stations respectively controlling communications through a first set of base stations including a first base station and through a second set of base stations including a second base station. To direct communications between the remote unit and the first and second base stations the first base station measures a round trip delay of an active communication signal between the first base station and the remote unit. The remote unit measures a first phase offset of a pilot signal received from a first candidate base station and reports it to the first mobile switching center via the first base station.

Abstract: The present invention is a novel and improved method and apparatus for decoding a frame of digital data which contains redundant information provided to validate the decoding operation. In the present invention, a frame of data contains information bits and cyclic redundancy check (CRC) bits. The received frame is decoded and a check is conducted to determine whether the CRC bits correspond correctly for the decoded information bits. If the decoded frame passes the CRC test process, the decoded fame is provided to the user. However, if the decoded frame does not pass the CRC test, then at least one additional decoding process is performed on the received frame. In the first exemplary embodiment of the present invention, if the CRC test is failed, a noise vector of a predetermined set of noise vectors is summed with the received frame and the resultant frame is decoded for a second time.

Abstract: The present invention teaches an equalizer preprocessor for a mobile telephone speech coder that adapts to the characteristics of its input transducer. The equalizer determines the frequency response of the input transducer by measuring the long term characteristics of the input signal and estimating the spectral envelope of that signal. The equalizer then adapts so that the output signal has a spectral response closer to a perceptually ideal response in accordance with the calculated spectral envelope. In a first embodiment of the present invention, the adaptive equalizer is implemented using digital filtering techniques. The equalizer determines a set of long term autocorrelation coefficient values and from these values generates a set of filter taps which serve to whiten or flatten the spectral response of the input signal. This whitened signal is then passed through a target filter which impresses upon the whitened signal the target spectral response.

Abstract: In a communication system capable of variable rate transmission, scheduling of high speed data transmission improves utilization of the reverse link and decreases the transmission delay in data communication. Each remote station is assigned a maximum unscheduled transmission rate for the duration of the communication with a cell. A maximum scheduled transmission rate can be assigned by a channel scheduler for scheduled transmission of data traffic at high rates. The maximum scheduled transmission rate is assigned in accordance with a set of system goals, a list of system constraints, and collected information on the status of the communication network. Data is partitioned in data frames and transmitted over the reverse link at or below the maximum scheduled transmission rate which have been assigned to the scheduled user.