Abstract: A mobile communication network includes an antenna site shared by two or more telecommunications service providers. The antenna site includes a shared resource, such as an antenna, telecommunications equipment, or bandwidth, used by multiple service providers and connects to multiple signal processing centers, each of which belongs to one of the service providers. The signal processing centers may provide modulating signals to the antenna site to use in modulating a carrier. The antenna site may also direct received signals from mobile terminals to the signal processing center for the appropriate service provider. A billing module at the antenna site maintains an accounting of resources used by each service provider.

Abstract: A method of broadcasting commercial FM services in a digital format in at least one bitstream comprises time-division multiplexing the bitstream(s) into one or more channels comprising a data frame, and frequency modulating the data frames around a single carrier frequency into a commercial FM broadcast signal. The modulation may comprise GMSK or 8-PSK, and multiple data frame types may be interleaved. The signal is transmitted on a commercial FM broadcast station such that substantially the entire spectrum of the transmission comprises the digital data frames. The bit rate(s) of the digital bitstream(s) may be monitored, and the bitstream(s) may be reallocated to channels in the data frames based on changes in the bit rate(s). Analog and digital formats may be broadcast simultaneously on non-adjacent commercial FM broadcast carrier channels. A receiver is operative to extract and decode content from a digital format FM broadcast signal.

Abstract: Transmit signal loop-back by a wireless receiver permits a transmitting network to estimate the characteristics of downlink propagation channels between one or more network transmitters and the receiver based on the loop-back signals. Downlink channel estimates may be, for example, used by the network in transmit pre-filtering. With transmit pre-filtering, transmit signals are compensated before transmission for the effects of the downlink propagation channels to, for example, reduce interference between multiple information signals being simultaneously transmitted to a number of wireless receivers. Loop-back techniques include but are not limited to the involved wireless receivers looping back at least a portion of the signal received from the transmitting network, which may then be processed by the network to estimate downlink channels. In some cases, the receivers may estimate downlink channels and provide these estimates to the network.

Abstract: A dual mode telephone is used with a satellite communication adapter. A cellular-type handportable phone is equipped with a connector for the attachment of accessories. This connector provides a satellite communications adapter accessory access to the handset's signal processing resources which may operate in an alterative 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: Communication systems and methods are provided allowing a single mode mobile terminal to support mobile assisted signal strength measurement operations in both a fixed frequency reuse based communication network and an adaptive channel allocation based communication network. Candidate base station signal strength measurements are requested by a fixed frequency reuse type network, measured by the mobile terminal and provided to the fixed frequency reuse type network which is seeking to identify a strongest signal for mobile assisted handover operations. In addition, interference signal strength measurements are requested by an adaptive channel allocation type network, measured by the mobile terminal and provided to the adaptive channel allocation type network by the mobile terminal. No redundant circuitry is required in the mobile terminal.

Abstract: Processing of loop-back information returned by one or more mobile stations that are served by a wireless communication network permits the network to compensate its transmit signals for increased transmission efficiency and reduced signal interference at the mobile stations. Generally, the network forms one or more transmit signals as a combination of different signals intended for the different mobile stations, and remembers transmit information associated with these transmit signals. The mobile stations return loop-back signals to the network, which determines transmit signal compensation information by comparing loop-back information to memorized information. The mobile stations may loop-back samples from composite received signals, from processed received signal samples, or loop-back estimates.

Abstract: A first, transmitting, device transmits a digitized data message using a short range radio link followed by digital data representing a digitized acoustic signal, such as a tone. Simultaneously, or with a predetermined time delay, the transmitting device emits an acoustic version of the same signal using an acoustic transducer such as a loudspeaker. A second, receiving, device receives the data message and the digitized acoustic signal via the short range radio link and receives the acoustic version of the signal via a microphone, which converts the acoustic signal to a second digitized version of the acoustic signal. Digital signal processing circuits then correlate the second digitized signal received acoustically with the digitized acoustic signal received over the short range radio link to determine a time difference of arrival.

Abstract: A spread spectrum signal is processed by correlating the spread spectrum signal with a spreading sequence at a first plurality of correlation times to produce a first plurality of time-offset correlations. The first plurality of time-offset correlations is processed to produce a first symbol representation for a symbol. A first quality is determined for the first symbol representation. Responsive to the determined first quality, it is determined whether to further process the first symbol representation or to process a second symbol representation for the symbol generated from the spread spectrum signal. The first quality may be determined, for example, by decoding the first symbol representations to generate a decoding metric or error check indicator, such as a CRC result. The symbol representations may be generated and/or evaluated for quality in a serial fashion or a parallel fashion.

Abstract: A method and apparatus for demodulating a communication signal transmitted at a first rate is provided, wherein the communication signal includes a plurality of addresses and corresponding data packets. The demodulating method includes the steps of receiving the communication signal at a user terminal, identifying which of the plurality of data packets are destined to the receiving user terminal, and demodulating, at a second rate less than the first rate, only the data packets identified as being destined to the receiving user terminal.

Abstract: A method and apparatus for performing cryptographic computations employing recursive algorithms to accelerate multiplication and squaring operations. Products and squares of long integer values are recursively reduced to a combination of products and squares reduced-length integer values in a host processor. The reduced-length integer values are passed to a co-processor. The values may be randomly ordered to prevent disclosure of secret data.

Abstract: A method and system for facilitating handover in mobile radio communication systems are disclosed. The mobile unit assists in making handover decisions by monitoring the signal strength of control channels transmitted by base stations in neighboring cells. During the handover, the mobile station can receive the same information from and/or transmit the same information to a plurality of base stations to provide diversity combination and improve transmission quality.

Abstract: A receiving apparatus comprises a receiver receiving signals via multiple propagation paths having different propagation delays and converting the signals to digital samples for processing. A channel estimator is operatively coupled to the receiver for correlating periodically selected groups of the digital samples corresponding to known symbols and periodically producing numerical estimates related to amplitudes and phases of the delayed propagation paths. A filter system filters the numerical estimates using filters periodically adapted to center frequencies of variations of the numerical estimates. A data decoder is operatively coupled to the receiver and the filter system for decoding data using the filtered estimates and the digital data.

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 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: Methods and systems for amplitude-modulating a power amplifier based on sensed current and sensed voltage provided to the power amplifier are provided. The sensed current and sensed voltage may be summed to provided both current and voltage feedback to modulate the power supplied to the power amplifier. Alternatively, both the current feedback and the voltage feedback may be selectively utilized to modulate the power supplied to the power amplifier.

Abstract: A time-division multiple access (TDMA) base station is disclosed for preserving across-slot signal continuity of signals transmitted in different directions on a given frequency. The base station includes a multi-directional antenna for radiating signals. A processor is operatively coupled to the antenna for generating a first data signal for a first time slot of a TDMA frame including a first pre-determined symbol pattern and a second pre-determined symbol pattern, for generating a second data signal for a second time slot of the TDMA frame including the second predetermined symbol pattern, and for communicating the first data signal and the second data signal to the antenna such that the first data signal is radiated in a first direction and the second data signal is radiated in a second direction. The first data signal is modulated at a first phase for transmission in the first time slot at a first power level in the first direction on the given frequency.

Abstract: An access control system includes an access control device, a wireless communication device, and a central controller. The central controller issues authorization codes to the wireless communication device. The wireless communication device is used by an authorized party to enable or activate a protected function secured by an access control device. To enable or activate the protected function, the authorized party uses the wireless communication device to transmit an access request to the access control device, which responds by transmitting an authentication challenge to the wireless communication device. The wireless communication device must transmit a valid authentication response based on the authentication challenge and a valid authorization code stored in its memory. If a valid authentication response is received, the access control device enables or activates the protected function.

Abstract: An apparatus and method decode information signals which have been encoded using a tailbiting error-correction codeword. The method generally includes the steps of initializing a number of decoder states corresponding to all possible starting states of the encoder to have equal associated likelihood metrics. The metrics are updated to reflect a likelihood metric for each of the decoder states given the received information signals. Further information signals, representative of further coded symbols, are received and a decoder state having the highest associated likelihood metric is extended by updating the likelihood metric to produce new likelihood metrics for each possible hypothesized extended decoded information symbol, given the further received information signals. An assumed value for the extended decoder information symbol is appended to the symbol history for the extended decoder state.

Abstract: A mobile radio telephone having a simplified architecture including a reduced number of integrated circuits and a reduced number of RF connections. A dual band, dual mode mobile phone can be constructed using either a single crystal reference oscillator or two crystals such that alternative symbol rates, channel spacings, or transmit/receive duplex spacings can be achieved.

Abstract: An improved satellite communications system allows for greater spectral efficiency by requiring just two frequencies for wireless communications between a first ground-based station and a second ground-based station via a satellite. Both the first station and the second station use the first frequency to transmit signals to the satellite; the satellite transponds the signals it receives on the first frequency to the second frequency and transmits the signals to the first and second stations on the second frequency. Use of two frequencies in such a manner results in some own-signal interference. The first station preferably stores its outgoing signals in memory and then subtracts out these stored signals to eliminate the its own-signal interference. The second station may likewise store and subtract out its transmissions, but this is not required.

Abstract: A method for processing a signal modulated with information symbols to account for an additive offset and slope is disclosed. First, an initial estimate of offset and slope is made and hypotheses of all possible values of a sequence of one or more information symbols are then made. For each of said hypotheses, the associated data symbol sequence is used to make an improved estimate of offset and slope and the improved estimate of offset and slope are stored against each of the hypotheses. For each hypothesis, the improved estimate of offset and slope is used in calculating an expected signal value and a mismatch between a sample of the modulated signal and the expected value is computed.