A cellular telephone system includes a plurality of cell sites and a mobile telephone switching office. Call management, including selection of a cell site most appropriate for a call associated with a mobile unit, are made based on the geographic location of the mobile unit as opposed to the strength of the signal associated with the call. The geographic location of the mobile unit is precisely determined using a NAVSTAR global positioning system, or its equivalent. Each mobile unit includes a GPS receiver that receives information from a geostationary satellite to determine the precise location of the mobile unit. This position information is relayed to the cell site initially managing the mobile unit, and the mobile unit is handed off to a cell site that is most appropriate for the call. Initial selection of an entrance cell site is made based on signal strength, but further call management decisions are made based on location of the mobile unit.

Cellular telephone system that uses position of a mobile unit to make call management decisions

An apparatus and a method for routing data in a radio data communication system having one or more host computers, one or more intermediate base stations, and one or more RF terminals organizes the intermediate base stations into an optimal spanning-tree network to control the routing of data to and from the RF terminals and the host computer efficiently and dynamically. Communication between the host computer and the RF terminals is achieved by using the network of intermediate base stations to transmit the data.

Radio frequency local area network

The high quality PCS communications are enabled in environments where adjacent PCS service bands operate with out-of-band harmonics that would otherwise interfere with the system's operation. The highly bandwidth-efficient communications method combines a form of time division duplex (TDD), frequency division duplex (FDD), time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM), spatial diversity, and polarization diversity in various unique combinations. The method provides excellent fade resistance. The method enables changing a user's available bandwidth on demand by assigning additional TDMA slots during the user's session.

Method for frequency division duplex communications

A technique for spread-spectrum communication which uses more than one mode and more than one frequency band. Selectable modes include narrowband mode and spread-spectrum mode, or cellular mode and microcellular mode. Selectable frequency bands include both licensed and unlicensed frequency bands, particularly frequency bands including the 902-928 MHz, 1850-1990 MHz, and 2.4-2.4835 GHz frequency bands. Spread-spectrum communication channels are 10 MHz or less in width. The frequency band onto which spread-spectrum signals are encoded may be changed upon a change in environment or other control trigger, such as establishment or de-establishment of communication with a private access network. A multi-band transmitter comprises a single frequency synthesizer and a frequency source (e.g., a local oscillator), coupled to a selectable band pass filter. A multi-band receiver capable of monitoring one or more frequency bands comprises bank of bandpass filters and a demodulator comprising a single frequency synthesizer and a frequency source.

Multi-band, multi-mode spread-spectrum communication system

Improved apparatus for a radio communication system having a multiplicity of mobile transceiver units selectively in communication with a plurality of base transceiver units which, in turn, communicate with one or more host computers for storage and manipulation of data collected by bar code scanners or other collection means associated with the mobile transceiver units. A network controller and an adapter which has a simulcast and sequential mode provide selective interface between host computers and base transceivers. A scheme for routing data through the communication system is also disclosed wherein the intermediate base stations are organized into an optimal spanning-tree network to control the routing of data to and from the RF terminals and the host computer efficiently and dynamically. Additionally, redundant network and communication protocol is disclosed wherein the network utilizes a polling communication protocol which, under heavy loaded conditions, requires that a roaming terminal wishing to initiate communication must first determine that the channel is truly clear by listing for an entire interpoll gap time. In a further embodiment, a criterion used by the roaming terminals for attaching to a given base station reduces conflicts in the overlapping RF regions of adjacent base stations.

Network supporting roaming, sleeping terminals

A system for reducing receiver power consumption in communication system having a transmitter (141) and one or more receivers (146) schedules periodic message in 'slot'. Each receiver is assigned a slot during which it monitors the transmission. The transmitter (141) transmits messages to the receiver only during the assigned slots. The receiver is in an 'active state' during its assigned slot. During the 'inactive state', which is the time period between successive occurrences of its assigned slot, the receiver may perform any action not requiring coordination with transmitter. At a time during the inactive state shortly before the assigned slot, the receiver applies power to these components and performs initialization. Such initialization may include reacquiring a pilot channel signal to which the receiver may synchronize itself if its timing signal have drifted out of synchronization with those of the transmitter during the preceding inactive state.

Apparatus and method for reducing power consumption in a mobile communications receiver

The process and apparatus of the present invention limits the output power of a radiotelephone, operating in a cellular system in the preferred embodiment. This ensures the transmitted sidebands and synthesizer phase noise remains within a certain specification. This is accomplished by power detection and a correction accumulator that together generate a gain control signal by limiting the gain adjustment to a maximum value, even when the cell site communicating with the radiotelephone is sending power turn-up commands to the radiotelephone. This process includes dynamically correcting the output level of the transmitter due to gain variations in the transmitter stages or gain control elements.

Reverse link, transmit power correction and limitation in a radiotelephone system

A method and apparatus (20) for converting phase data into amplitude data. Input phase data (x) is divided into upper phase increment (a) and lower phase increment (x-a) using an input splitter (24). Storage element, such as ROM (26), is connected to the input splitter (24) and generates an amplitude (A), which is a first series term, and first (d/dx) and second (d2/dx2) derivatives in response to the upper phase increment (a). A digital multiplier (28) multiplies the first derivative (d/dx) and lower phase increment (x-a) to produce a second series term ((x-a)d/dx). A term (k) is generated by a term generator (36) connected to the splitter (24). A third series term comprising a product of the term (k), the second derivative (d2/dx2) and phase increment squared (x-a)2. The first, second and third series terms are subsequently added together by digital adder (34) to form an output amplitude.

High resolution phase to sine amplitude conversion

A method and apparatus for reducing spurious output noise in digital frequency synthesizers that employ a sine amplitude converter (16) connected to a Digital-to-Analog converter (18) for generating an analog waveform from sine amplitude data. The method comprises the steps of adding random or pseudorandom numbers which are scaled to have a predetermined magnitude to the sine amplitude data and transferring a resulting addend to the Digital-to-Analog converter (18). The apparatus comprises a summation circuit (22) connected between an output of the sine function converter (18) and an input of the digital-to-analog converter and connected to a random or pseudorandom number generator (24) at a second input. A scale element (26) adjusts the pseudorandom number magnitude to provide numbers having values in the range +/- 1/2 times a minimum quantization step or at least significant bit of the Digital-to-Analog converter (18) resolution where n is greater than or equal to 1.

Pseudorandom dither for frequency synthetis noise.

A detection circuit that detects the open and close state of a flip cover of a communications device. The detection circuit includes a resistive network and an analog-to-digital converter (ADC). When the flip cover is in the closed position, the circuit detects a unique resistive value through a set of contacts. This voltage level is converted from an analog signal to a digital signal via the ADC for input into a microprocessor. When the flip cover is in the open position, the contacts are broken, thus, disabling the detection of the unique resistive value. The resulting voltage level is converted from an analog signal to a digital signal via the AD for input into a microprocessor. Software, programmed within the microprocessor, enables the communications device to operate in the appropriate mode according to the detection of the open/close state of the flip cover.

Kerr Richard J

Papers

Apparatus and method for reducing power consumption in a mobile communications receiver

Reverse link, transmit power correction and limitation in a radiotelephone system

High resolution phase to sine amplitude conversion

Pseudorandom dither for frequency synthetis noise.

Detection of flip closure state of a flip phone