Abstract: A method and apparatus for protecting a first group of data bits using a second group of data bits within digital data transmissions is disclosed. First and second groups of data bits are encoded for transmission in a communication network. The second group of encoded data bits are scrambled using a scrambling mask generated from the first group of data bits. The first group of encoded data bits and the second group of encoded and scrambled data bits are then interleaved and transmitted to a receiver. The first group of data bits are decoded and used to regenerate the scrambling mask to descramble the second group of encoded and scrambled data bits. The second group of data bits may then be decoded. The results of the decoding of the second group of data bits are used to determine whether or not the first group of data bits were properly decoded.

Abstract: The disclosure presents a number of reduced complexity architectures for despreading direct sequence spread spectrum communications signals. In a first despreading architecture for a sequence removal unit, received chip-spaced complex samples are negated in accordance with the processed phase of a complex spreading sequence. Furthermore, the in-phase and quadrature phase sample values are switched for each other in accordance with the processed phase. In a second despreading architecture, in a sequence removal unit, received chip-spaced complex samples are processed in the logarithmic domain, with the phase of the complex spreading sequence added to the detected phase, and the resulting complex signal then converted back to Cartesian coordinates. In a third despreading architecture for a correlator, sequence removal and correlation are performed in the logarithmic domain with the amplitudes and phases for the resulting complex signal arithmetically averaged and then converted back to Cartesian coordinates.

Abstract: A method and apparatus for mapping a cellular bit stream to a wireline modem waveform is disclosed. A received cellular bit stream is applied to convolutional decoder to decode class I speech bits within each bit frame of the cellular bit stream. The decoder speech bits are appended to the bit frame from which the decoded bits came, and a 40 bit frame marker is attached to each bit frame. This modified bit frame is transmitted at 20 mS intervals to a wireline modem to achieve a 19.2 KB/S bit rate. The line modem maps the signal onto a waveform and transmit the signal to a PSTN network.

Abstract: In a mobile radio-telephone system including at least one base station transmitting information to subscriber telephones indicating whether they are being called, a method comprising the steps of dividing a repetitive frame period into a number of sleep-mode slots, determining a sleep-mode slot number to be used for transmitting a call to a particular subscriber telephone using an assigned subscriber telephone number, transmitting a calling message in said determined sleep-mode slot including the assigned subscriber telephone number, repeating transmission of the calling message a number of times as determined by system loading and available capacity to transmit such calls, and transmitting an indication of the number of repeated transmissions capacity and loading currently permits.

Abstract: A wireless apparatus is described having a transmitter and a receiver controlled by a frequency synthesizer arrangement to operate on a transmit frequency channel and a receive frequency channel respectively. The transmit frequency channels are not spaced by the same amount in the transmit frequency band as the receive channels are spaced in the receive band, but by a sub-multiple of the receive channel spacing, for example.

Abstract: A method and apparatus of communicating information using Time Division Multiple Access and adaptive transmission and reception are disclosed. Signal bursts are transmitted from TDMA transmitters to a TDMA receiver wherein the transmitter codes the information and transmits coded information to the receiver using at least one of two timeslots of a plurality of timeslots in a repetitive TDMA frame period. Both of the two timeslots are received whether or not the transmitter has transmitted using one or two timeslots and the received signals are classified as intended and non-intended. Successively received signals classified as intended are then assembled into a block for decoding to reproduce the information.

Abstract: Methods and apparatus for mobile station to mobile station communications in a mobile satellite communications system include an asymmetrical TDMA formatting scheme. According to exemplary embodiments, a first mobile station broadcasts a first signal to an orbiting satellite using a first TDMA format. The satellite receives the first signal, maps the first TDMA format to a second TDMA format and broadcasts a second signal having the second TDMA format to a second mobile station. Advantageously, exemplary embodiments utilize an elastic buffer to allow the satellite to map the uplink TDMA format to the downlink TDMA format without having to demodulate and re-modulate communications signals.

Abstract: Paging systems typically include a network of ground stations or orbiting satellites equipped with transmitters and antennas for transmitting paging messages to small, battery-operated paging receivers that are worn about the person, known as pagers. Conventional pagers are receive-only devices and the network receives no confirmation that paging has been successful. The present invention includes the provision of two-way pagers that contain a transmitter for transmitting an acknowledgment confirming reception of a paging message, and a network of receiving stations able to receive said acknowledgments. The network makes use of advanced phased-array antenna signal processing techniques to render the return link operable with much less transmitter power in the portable unit than employed by the base station.

Abstract: Establishing a connection between a paging unit and a standby unit in a channel hopping communications system includes activating the standby unit for an activation time period out of every standby time period. During each activation time period, the standby unit monitors a selected channel for receipt of a paging message. The selected channel is selected from a plurality of channels, and, for each subsequent activation time period, the selected channel is a subsequent one of the plurality of channels as specified by a hopping sequence and an internal clock. A page train is repeatedly transmitted from the paging unit to the standby unit, until a response is received from the standby unit. Each page train includes a plurality of paging messages, each paging message being transmitted on a different one of a subset of the plurality of channels. Selection of a page train for transmission by the paging unit may be based on an estimate of the standby unit's internal clock.

Abstract: A digital information bit that has been encoded and transmitted as a first modulated signal from a first transmitter in the presence of a second modulated signal that has been transmitted by a second transmitter is received and decoded by receiving a composite signal that is a sum of the first modulated signal and the second modulated signal. The composite signal is processed to generate a complex numerical sample. Then, a plurality of bit pairs are hypothesized, wherein each hypothesized bit pair includes a hypothesized first information bit encoded and transmitted by the first transmitter and a hypothesized second information bit encoded and transmitted by the second transmitter. For each of the plurality of hypothesized bit pairs, a path metric is generated that is indicative of a likelihood that information sequence estimates are accurate estimates, wherein the information sequence estimates include the hypothesized first and second information bits.

Abstract: The details of an improved correlator and efficient method of correlation are disclosed. The last M received signal samples are compared with all shifts of a given M-bit binary codeword. The correlator adds or subtracts each of the signal samples accordingly, as the corresponding shift of the codeword contains a binary "1" or "0" in that position. The total is output for each new signal sample received, with a shift of one position between the signal samples and the codeword.

Abstract: A multi-channel transmit amplifier array comprising a multiplicity N of coupled power amplifier elements is disclosed. The number of channels provided for amplifying desired signals for transmission is less than N, by at least one. In this case, the unused channel is used to inject an intermodulation compensation waveform specifically tailored to reduce intermodulation generated in all of the other N-1 signal paths. Instantaneous complex waveform values for the intermodulation compensation waveform may be systematically computed from the instantaneous complex values of the N-1 desired signals in such a way as to minimize the greatest signal amplitude in any of the N signal paths.

Abstract: A method and apparatus for providing a homodyne cellular base station. A cellular antenna is coupled to both a conventional signal channel receiver a homodyne receiver. The conventional single channel receiver is configured to receive the control channel from a cellular band signal. The homodyne receiver utilizes a quadrature downconverter and local oscillator to receive the voice channels. The local oscillator is tuned to the frequency of the control channel to limit all DC offsets to the control channel within the homodyne receiver. All DC offsets and the control channel frequency are filtered from the homodyne receiver signal and, the filtered signal is then digitized and digitally processed to separate the signal into each of the traffic channels.

Abstract: A communication system and method for communicating data bits includes generating error detection bits for interspersing within a sequence of data bits to be transmitted to provide a message to be transmitted. The interspersed data bits may be dependent on the data bits or determined independent of the data bits. The message to be transmitted is convolutionally encoded and transmitted through a communications medium. The received message is convolutionally decoded by a convolutional decoder which is operably connected to an error indication logic circuit. The interspersed error detection bits may be used to detect an uncorrected error in transmission or to constrain the convolutionally decoding to provide an improved error correction operation based on the determinate values of the interspersed error detection bits.

Abstract: A digital beamforming network for transmitting a first number of digital information signal using a second number of antenna array elements is disclosed. Assemblers are used for assembling one information bit selected from each of the information signals into a bit vector. Digital processors have an input for the bit vector and a number of outputs equal to the second number of antenna elements and process the bit vector. Finally, modulation waveform generators coupled to each of the second number of outputs generate a signal for transmission by each antenna element.

Abstract: A dual-mode telephone with a satellite communication adapter is disclosed. According to one embodiment of the present invention, a cellular-type handportable phone is equipped with a connector for the attachment of accessories. This S connector provide a satellite communications adapter accessory access to the handset's signal processing resources which may operate in an alternative mode to process signals received from the satellite and converted by the adapter into a suitable form for processing. The processing translates the satellite signals into voice or data, and vice-versa.

Abstract: A short-range wireless radio communications system is provided that can carry data, voice, or data and voice traffic simultaneously. The band is divided into a plurality of channels or hops, and a burst composed of either voice information, data information, or a combination of data and voice information is transmitted during one of the hops. The system operates preferably in a simplex mode, but full duplex operation can also be employed. The present system can also be operated in a cellular, TDMA system. A multiple time slot method is employed whereby one time slot can carry data and another time slot can carry voice information.

Abstract: A multiple access communication system and method using Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA) comprises coding information signals with CDMA codewords to be transmitted over a common frequency spectrum, time compressing the CDMA codewords for transmission only during allocated timeslots, activating a receiver only during the allocated timeslots to receive and decompress the time compressed CDMA codewords, and decoding the decompressed CDMA codewords to recover the information signals.

Abstract: A synchronization method and apparatus for synchronizing a receiver, such as a radiotelephone operable in a cellular communication system with a transmitter. Synchronization sequences are transmitted as parts of a control signal to the receiver. The synchronization sequences are formed of either a dotting sequence or a set of m-sequences. Such synchronization sequences are of high margins and also permit synchronization of the user terminal responsive to a reduced number of calculations.

Abstract: Radio transmissions are spectrally contained to reduce adjacent channel interference by a method and apparatus for I,Q filtering of signals before quadrature modulation in digital cellular radio transmission systems such as communications systems following the GSM TDMA, IS-54 or IS-95 standards. The filtering is accomplished by multiple stage registers connected at their complementary outputs to identical resistor networks. The outputs of the resistor networks are summed to represent a smoothly transitioning analog representation of the digital voice or data transmission. The analog representation may be additionally low pass filtered to remove higher frequency components before quadrature modulation. Because rapid transmissions in the transmittal signal are avoided, adjacent channel interference is reduced.