Abstract: Aspects of global positioning system (GPS) technology and cellular technology are combined in order to provide an effective and efficient position location system. In a first aspect of the invention, a cellular network is utilized to collect differential GPS error correction data, which is forwarded to a mobile terminal over the cellular network. The mobile terminal receives this data, along with GPS pseudoranges using a GPS receiver, and calculates its position using this information. According to a second aspect, when the requisite number of GPS satellites are not in view of the mobile terminal, then a GPS pseudosatellite signal, broadcast from a base station of the cellular network, is received by the mobile terminal and processed as a substitute for the missing GPS satellite signal.

Abstract: In a mobile communication network, the accuracy of location determinations for mobiles based on TDOA measurements made by the mobiles is increased by measuring the TDOA of signals from base station pairs at a known location and generating correction factors for compensating timing and propagation errors in TDOA measurements made by the mobiles. Calibration terminals may be provided for measuring TDOAs at known locations. System processes and elements for applying data generated by calibration terminals are disclosed.

Abstract: The radiotelephone demodulates the information received from the base station. The symbol-energy-to-noise-density (E.sub.s /N.sub.o) is estimated over a specified duration. This estimate is compared to a target E.sub.s /N.sub.o value. The target is updated periodically in order to maintain the quality of service. If the measured E.sub.s /N.sub.o is greater than the target, the radiotelephone sends a power down command over a reverse power control signaling channel to the base station. If the measured E.sub.s /N.sub.o is less than the target, the radiotelephone sends a power up command to the base station over the same channel. A multi-carrier transceiver system for a code division multiple access system includes circuitry for up-converting processed user data to a plurality of frequency channels. The transceiver, in some embodiments, further includes a plurality of antennas for transmitting each channel of user data.

Abstract: The present invention provides a system and a method for improving the voice quality of wireless-to-wireless calls. More specifically, the invention provides a method and an apparatus to add supplemental information for better error detection and correction of data packets. This feature allows the identification of the telecommunication link causing errors in the data packets and optimizes the use of the reconstructed data packets.

Abstract: The present invention provides a novel system and a method for improving the voice quality of wireless-to-wireless calls or wireless-to-fixed terminal calls, while permitting a more efficient utilization of network resources. In a first aspect, the invention provides a communication system including a plurality of base stations connected to one another through a digital network (such as TDM, frame relay or ATM). Also, a plurality of vocoder channels, separate from the individual base stations, provide a data flow path from the base stations to wireline terminals first through the digital network via a Mobile Switching Center and finally through a landline network. In a wireless-to-wireless call, the compressed audio signal travels from one base station to another without undergoing any de-compression/compression. This avoids undesirable vocoder tandeming known to degrade voice quality.

Abstract: In a receiver of a simulcast multi-carrier CDMA (code division multiple access) communications system, a combined data signal is produced by combining signals representing data received for the plurality of carriers and is multiplied by the complex conjugate of a composite reference signal, representing characteristics of the plurality of carriers, produced by combining signals representing a reference signal received for the plurality of carriers, thereby improving multi-path resolution due to frequency diversity of the reference signal over the multiple carriers of the system. The receiver can be simplified by demodulating the signals of the plurality of carriers in common to produce a demodulated signal which is common to the data and reference signals for the plurality of carriers, the data and reference signals being subsequently separated using their respective orthogonal codes.

Abstract: A mobile communication system and communication device for providing location services. Time difference of arrival (TDOA) measurements are used to determine the location of a mobile of the network. The location may be forwarded to a service provider. The location may alternatively be used to determine service providers that are local to the mobile. Correction factors deprived from calibration TDOA measurements made at calibration terminals are applied to the TDOA measurements enhance the accuracy of the location determination.

Abstract: The present invention provides novel systems and methods for improving the voice quality of wireless-to-wireless calls or wireless-to-fixed terminal calls. This disclosure describes methods and apparatuses to determine and control the quality of service objectives in a telecommunication network involving at least one wireless terminal.

Abstract: In recent years, the telecommunications industry has witnessed the proliferation of a variety of digital vocoders in order to meet bandwidth demands of different wireline and wireless communication systems. The rapid growth in the diversity of networks and the number of users of such networks is increasing the number of instances where two vocoders are placed in tandem to serve a single connection. Such arrangements of low bit-rate codecs can degrade the quality of the transmitted speech. To overcome this problem in the specific situation involving store-and-forward systems (e.g. voicemail), the invention provides a novel method and apparatus including a plurality of different vocoders that can be selectively invoked to process the voice signal so as to reduce signal degradation. Also, the apparatus has the capability to bypass the vocoder bank when exchanging data with a remote signal processor capable of accepting data frames in compressed format.

Abstract: Aspects of global positioning system (GPS) technology and cellular technology are combined in order to provide an effective and efficient position location system. In a first aspect of the invention, a cellular network is utilized to collect differential GPS error correction data, which is forwarded to a mobile terminal over the cellular network. The mobile terminal receives this data, along with GPS pseudoranges using a GPS receiver, and calculates its position using this information. According to a second aspect, when the requisite number of GPS satellites are not in view of the mobile terminal, then a GPS pseudosatellite signal, broadcast from a base station of the cellular network, is received by the mobile terminal and processed as a substitute for the missing GPS satellite signal.

Abstract: The invention provides a means by which a radio system in a multipath propagation environment may improve the probability of successful reception of a message by the application of diversity. It is applicable to such applications as paging, cordless telephones, cellular telephones, and radio identification tags. The transmitter sends the message repeatedly, each repetition transmitted from a different antenna. The antennas are separated so that multipath fading of the signal arriving at the receiver from each transmit antenna is substantially uncorrelated with the multipath fading of the signal arriving at the receiver from the other transmit antennas. The receiver examines the radio channel for an incoming message for a time period long enough for it to potentially receive the message from each antenna.

Abstract: The call set-up technique of this invention is characterized by the use of channel information from both base station and subscriber terminal in determining the radio traffic channel upon which to set-up a new call. Communication between the base station and subscriber terminal is carried out on a signalling channel until the traffic channel is chosen. Calls are set-up so that they proceed on the radio channel which, of a set of channels under consideration by the subscriber terminal, contains the least amount of interference as measured at the subscriber terminal. The set of channels under consideration by the subscriber terminal is a subset of the entire set of channels allocated to the service. This subset is comprised of those channels having little interference, as measured by the base station. The call set-up technique thereby assures that calls proceed on channels containing little interference from the viewpoints of both base station and subscriber terminal.

Abstract: The intra-cell call hand-over technique of this invention is characterized by the use of channel information from both base station and subscriber terminal in determining a standby radio traffic channel upon which to hand over a call. Communication between the base station and subscriber terminal is carried out on an inband or associated signalling channel for the selection of the standby traffic channel. The standby radio channel is the channel, which, of a set of channels under consideration by the subscriber terminal, contains the least amount of interference as measured at the subscriber terminal. The set of channels under consideration by the subscriber terminal is a subset of the entire set of channels allocated to the service. This subset is comprised of those channels having little interference as measured by the base station. The call hand-over technique thereby assures that calls proceed on channels containing little interference from the viewpoints of both base station and subscriber terminal.

Abstract: An improved radio link architecture for digital wireless communication systems which is characterized by the use of information and signalling channels on a number of RF carriers, thereby providing common signalling channels for call set-up and control functions. A first group of RF carriers are allocated as traffic channels between base stations and subscriber terminals. Each RF carrier in the first group comprises at least one traffic channel. A second group of RF carriers is allocated for providing common signalling channels between the base stations and the subscriber terminals. Each RF carrier having common signalling channels operates in time division multiple access mode, and each common signalling channel being time division duplexed.

Abstract: The present invention provides a method and apparatus of making secure conference calls in which the bridging unit does not need to know any encryption keys and can function independently of the encryption process used by the communicating parties. This means that there is no security requirement for the conference unit, there are fewer restrictions on where it can be placed, and it does not introduce any additional weaknesses in the security system.

Abstract: A conference circuit has a plurality of ports for a corresponding plurality of conferees. Associated with the ports is a control circuit which determines whether a conferee is active, i.e. talking, or dormant, i.e. listening. The circuit applies gain to the "active" signals and attenuates the "dormant" signals. When a listener starts to talk, the circuit switches his port to the "active" mode. Difficulties arise in determining when a listener becomes active, due to noise and echo with the speech signal. They are mitigated by comparing the signal from the port with an echo signal estimate derived from the echo return loss for the transmission path associated with the port. The arrangement takes account of differing echo levels for different transmission paths.

Abstract: An ADPCM encoder and decoder includes an adaptive quantizer and an adaptive predictor. A quantizing-step-size adaptation circuit determines a quantizing-step-size for the adaptive quantizer in dependence upon the ADPCM signal. When the quantizing-step-size is small, updating of predictor coefficients, produced in the adaptive predictor, in dependence upon a reconstructed signal and a reconstructed error signal derived from the ADPCM signal, is inhibited, the predictor coefficients being updated only in dependence upon a leakage function. This enables improved tracking to be achieved by the ADPCM arrangement.

Abstract: In an ADPCM transmission system, signalling frames of an incoming multiplexed PCM signal are identified and signalling bits extracted therefrom. During each signalling frame, an ADPCM encoder/decoder is controlled by the signalling frame signal to operate entirely for 3-bit ADPCM, instead of the regular 4-bit ADPCM, to which 3-bit ADPCM the extracted signalling bits are added for transmission. The deliberate alteration from 4-bit to 3-bit ADPCM at the encoder and decoder of the system in each signalling frame ensures proper adaptation and consequently no loss of tracking between the encoder and the decoder.

Abstract: Samples of a transmit path voice channel signal are averaged and compared with an adaptive speech threshold to determine the presence of speech. When the average falls below a fixed threshold, a timing circuit is triggered to time a delay period followed by a noise averaging period. The timing of these periods is aborted if either the transmit path average, or a similarly produced receive path average, exceeds the fixed threshold during either period. During the averaging period the voice channel signal is averaged, and at the end of this period the average noise level is used to determine the adaptive speech threshold, a predetermined level above the average noise level, the new adaptive speech threshold being stored. The stored adaptive speech threshold is not changed unless the timing of the delay and averaging periods is completed, ensuring that only the noise is averaged to determine the adaptive speech threshold.