Hughes Aircraft Company

Interdigital Technology Corporation

Other

Hughes Electronics Corporation

David M Cooley

John D Kaewell

Scott David Kurtz

Mark A Lemmo

Michael W Regensburg

David Vessal

Joseph J DiGiovanni

Eric Johns

Youngky Kim

A subscriber cluster unit for a wireless telecommunication system provides a wireless interface with a base station for a plurality of subscriber units. The cluster unit has a plurality of frequency agile modems for processing wireless communications with the base station and a plurality of subscriber line circuits, each for providing a telecommunication connection with a subscriber unit. A control processor assigns a modem for each communication between the base station and a selected subscriber unit which is coupled to one of the line circuits and associates that line circuit with the assigned modem for that communication. Thus, a subscriber unit coupled with any of the line circuits can communicate with the base station via any of the modems.

Modularly clustered radiotelephone system

A power-conserving time division multiple access (TDMA) radio telephone system is disclosed in which a cluster of subscriber stations, remote from a base station, employs a common pool of frequency-agile modems each of-which digitally synthesizes, on a timeSlot-by-timeSlot basis, the different channel-identifying intermediate frequencies needed to support communications between several of the subscriber stations and the base station. Power conservation is facilitated inter alia by controlling the assignment of modems to calls, maintaining unassigned modems in a powered-down state and by controlling the number of calls using the same time slot. Delay in assigning a powered-down modem to a call is eliminated by making available to all modems the highest quality synchronization information obtained by any of the active modems.

A power-conserving time division multiple access (TDMA) radio telephone system is disclosed in which a cluster of subscriber stations, remote from a base station, employs a common pool of frequency-agile modems each of which digitally synthesizes, on a timeSlot-by-timeSlot basis, the different channel-identifying intermediate frequencies needed to support communications between several of the subscriber stations and the base station. Power conservation is facilitated inter alia by controlling the assignment of modems to calls, maintaining unassigned modems in a powered-down state and by controlling the number of calls using the same time slot. Delay in assigning a powered-down modem to a call is eliminated by making available to all modems the highest quality synchronization information obtained by any of the active modems.

Modulary clustered radiotelephone system

A Supervisory Audio Tone (SAT) based Carrier-to-Interference (C/I) ratio measurement system uses the SAT tone to determine the desired signal to undesired interferers so that an intelligent hand-off decision can be made in a digital cellular communication system. The measurement is implemented by digital signal processors which allows additional signal processing and subsequently noise rejection over analog techniques. The received level of the desired SAT as well as the received levels of the SATs for the co-channel interferers is detected. The ratio of the desired SAT level to the sum of the undesired SAT levels provides the C/I measurement. By monitoring this C/I measurement, the base station can determine when to make a hand-off. This SAT based C/I measurement system also aids in the selection of a candidate cell to which the subscriber is handed-off. Surveillance receivers in the candidate cells make SAT based C/I measurements as well as Received Signal Strength Indication (RSSI) measurements. The cell with the most favorable channel conditions would be the cell to which the hand-off is made.

Supervisory audio tone based carrier-to-interference measurement in a

An internal bit error rate (BER) test capability is built into the analog channel unit of a digital cellular base station. This test capability is controlled by the mobile telephone switching office (MTSO) to automatically perform BER measurements. The analog channel unit with this integrated function performs random sequence generation, continuous frequency shift keying (FSK) modulation, FSK random sequence acquisition, FSK demodulation and bit error tallying. The BER test functions built into the analog channel unit allow the tests to be performed via remote control from an operations and maintenance center of the MTSO. Having the BER test functions built into the analog channel unit reduces the number of physical interfaces which the analog channel unit has to support.

Integrated bit error rate test function in analog channel unit of

A compatible analog channel unit for a digital cellular telephone system services both analog and digital mode subscribers on the same system hardware. The analog channel unit which may be configured by the service provider to permit easy upgrading of service during the life of the equipment without additional capital expense to the service provider. All analog system functions required of an analog cellular base station are provided in firmware and executed on commercial digital signal processors (DSPs). The same DSPs, when down-loaded with different firmware, perform TDM/TDMA related functions as required of a digital cellular base station. A system operator can configure channel units from a remote location by simply downloading the appropriate firmware. The channel unit firmware, whether analog or digital, is downloaded into the system hardware according to the assigned mode. This permits dynamic channel allocation according to system requirements. Since this is a digital system, special features may be added by simply revising the system firmware. This means future product enhancements may be provided without affecting the system hardware.

Compatible analog channel unit for a digital cellular telephone system

A Digital Post-Detection (Post-Discriminator) FM spatial diversity combination circuit improves performance for fading channels typical of cellular radio operating environments. A feature of this system is its flexibility. The system can be configured to use signal quality information in a manner which is appropriate for a given radio environment. Also, the weighting information can be derived from various sources and then processed to accommodate various situations. This spatial combiner has the ability to perform as a 'hybrid' combiner. For example, this circuit can combine signals from various receivers based on soft weighting information, as in a maximal ratio combiner, or on hard weighting information, as in a switching combiner. The basic circuit includes a normalizing circuit (21, 22, 23) which receives the digitized received signal strength indicator samples from each of first and second receivers (11, 12) and generates first and second weighting signals. A first multiplier (24) multiplies the digitized discriminator samples from the first receiver by the first weighting signal to generate a first weighted output signal. A second multiplier (25) multiplies the digitized discriminator samples from the second receiver by the second weighting signal to generate a second weighted output signal. The first and second weighted output signals are combined in a post-detection, maximal ratio combining circuit (26).

Digital post-detection FM spatial diversity combination circuit

A modulator capable of providing a fractional sample or symbol 995486 time employs a decimation counter (23) responsive to a clock having a frequency equal to M/N.times.(data symbol clock), where M is an interpolation factor and N is a decimation factor, for generating a data symbol clock to select FSK symbols from a sampled data array (21). A multiplier (26) receives the FSK symbols and multiplies the symbols by a weighting factor determined by the decimation counter. When the decimation counter wraps around due to a modulo M operation, a fractional weight is calculated for the current FSK symbol, then a new FSK symbol is selected, and then a fractional weight is calculated for the new FSK symbol. When the decimation counter has not wrapped, the full weighting, N, is output for the current FSK symbol.

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Upper Darby, PA, United States of America

David M Cooley