Abstract: A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of which the base station transmits to a user station and the user station transmits to the base station. Communication is initiated by a round trip timing transaction. In response to a general polling message from the base station, a user station seeking to establish communication transmits a short reply message. The base station calculates the distance of the user station by measuring the propagation delay with respect to receipt of the reply message. The base station sends a timing adjustment command to the user station instructing the user station to advance or retard its timing according to the calculated distance, so as to minimize guard times between time slots.

Abstract: A mobile communication system having a layered architecture communicates user and signaling data among components of the communication system in the form of information elements which are encapsulated within packets and which may be passed across one or more system interfaces. The mobile communication system comprises mobile user stations, base stations, and base station controllers and operates as a transparent data pipeline between application end users, such as a telephone service, connected at base station controllers and mobile user stations. In a particular embodiment, the interface between the base station and the user stations is a TDMA interface, and signaling traffic between the base station and each of the user stations is conducted in either a fast control traffic mode or a slow control traffic mode.

Abstract: A simple and flexible over-air protocol for use with a mobile telephone system, having hand-held telephones in a microcell or other type of cellular communication system. A method in which user stations communicate with one or more base stations to place and receive telephone calls, in which the user stations are provided a secure voice or data link and have the ability to handoff calls between base stations while such calls are in progress. Each base station has a set of "air channels" to which it transmits in sequence. The air channels supported by each base station are called that base station's "polling loop". A user station receives general polling information on an unoccupied air channel, transmits responsive information to the base station, and awaits acknowledgment from the base station. Each base station may therefore simultaneously maintain communication with as many user stations as there are air channels in its polling loop.

Abstract: A receiver and antenna selection system located at a base station preferably comprises a plurality of radio units, each connected to its own antenna. Each radio unit receives a radio message and independently derives quality metrics based on the reception quality of the radio message, as indicated, for example, by a received signal strength indication, cyclic redundancy check result, preamble correlation magnitude, and other factors. Each radio unit transfers the quality metrics as serial data to an antenna selector. The antenna selector, simultaneously for each radio unit, converts and formats the serial data into individual data words and/or bits corresponding to the quality metrics, then applies the data words and/or bits to an antenna scoring block for determining an antenna score for each antenna. A comparison block compares the antenna scores and selects the best antenna for reception and/or transmission.

Abstract: A method and apparatus for a unique digital signature is provided. According to one aspect of the invention, a unique digital signature comprises an adapted digital signature and a service id. The adapted digital signature provides temporary or restricted privileges for a particular electronic service. In one embodiment, the electronic service is electronic message forwarding. In another embodiment, the electronic service is electronic media delivery. An authentication log file is maintained for recording status information concerning unique digital signatures.

Abstract: An adaptable DC power consumption circuit is provided, wherein the voltage supplied to an RF amplifier is dynamically varied from a desired level. A feedback control loop is formed between the power terminal and a control terminal of a variable voltage supply. A controller influences the feedback control loop to properly set the supply voltage at the desired minimum level necessary to maintain linear operation of the RF amplifier. The output of the RF amplifier influences the feedback control loop to dynamically vary the supply voltage from the desired level. In this manner, linear operation of the RF amplifier can be maintained while maximizing the power efficiency of the RF amplifier.

Abstract: A system for time division multiplexed communication over a single frequency band in which guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. In one embodiment, during a first portion of a time frame, a base station issues a single burst segmented into time slots comprising data directed to each user station. After a single collective guard time, the user stations respond, one by one, in allocated time slots on the same frequency as the base station, with only minimal guard times between each reception. In order to prevent interference among the user transmissions, the base station measures the round trip propagation time for each user station and commands the user stations to advance or retard their transmission timing as necessary.

Abstract: A technique for cyclic time hopping in a multiple access communication system, wherein each time frame of a TDMA system is divided into multiple time slots. A plurality of user stations, one for each time slot, communicate with a base station. Each user station regularly varies its relative time slot position in a pseudo-random pattern. Orthogonal time hopping patterns are determined from a root pattern according to a predetermined equation or relationship. The effect of transmitting bursts in a pseudo-random pattern is to break up the otherwise strict periodicity of TDMA bursts, and to produce a more noiselike spectrum for switching transients, thereby reducing the level of interfering spectral components from a TDMA transmission source. In some embodiments, the time hopping pattern may be restricted to only odd or even time slots. In such embodiments, a dead time slot may be declared periodically so as to increase the apparent randomness of the user station transmission patterns.

Abstract: A mobile communication system having a layered architecture communicates user and signaling data among components of the communication system in the form of information elements which are encapsulated within packets and which may be passed across one or more system interfaces. The mobile communication system may comprises mobile user stations, base stations, and base station controllers and operates as a transparent data pipeline between application end users, such as a telephone service, connected at base station controllers and mobile user stations. Each system interface functions as a communication channel between system components, providing the lower layers of a layered communication system architecture. In a particular embodiment, the interface between the base station and the user stations is a TDMA interface, and the interface between a base radio transceiver and a line card processor comprises a dual-port RAM which is used as a shared resource across the interface.

Abstract: An adaptable DC power consumption circuit is provided, wherein the current supplied to an RF amplifier is dynamically varied from a desired level. A feedback control loop is formed between the power terminal and the control terminal of the RF amplifier. A controller influences the feedback control loop to properly set the supply current at the desired minimum level necessary to maintain linear operation of the RF amplifier. The output of the RF amplifier influences the feedback control loop to dynamically vary the supply current from the desired level. In this manner, linear operation of the RF amplifier can be maintained while maximizing the power efficiency of the RF amplifier.

Abstract: A communication protocol for use in a mobile cellular communication system using time division duplex establishes a communication channel between a user station (e.g., a handset) and a base station in a time slot by assigning a first time segment within the time slot for a user station transmission and assigning a second time segment within the time slot for a base station transmission. The protocol also provides for virtual time slots wherein a time segment assigned for periodic transmission from the base station to a given user station may be non-contiguous with respect to the time segment assigned for periodic transmissions from the user station to the base station.

Abstract: A wireless communication system employing spread-spectrum communication techniques. A plurality of base stations may be coupled directly or indirectly to a telephone network and may initiate or receive calls on the telephone network. A plurality of user stations may comprise a spread-spectrum transmitter and receiver and may provide for dynamic connection to selected base stations. In one preferred form, one or more of the base stations may comprise an augmented base station and include means for communication with the user stations over an alternative communication path distinct from a spread-spectrum path, for example, over a cellular communication path. The augmented base stations may also communication with one or more cluster controllers, enhances service processors, or control stations coupled to the telephone network.

Abstract: In a first embodiment of the invention, a concatenated preamble code is formed by a kronecker product between two subcodes of the same or different lengths. The subcodes have favorable correlation properties and may be Barker codes, minimum peak sidelobe codes, Gold codes, Kasami codes, Bozta codes, or other codes. At the receiver a two-stage processor is used to detect the concatenated preamble code. The two-stage processor comprises a series of two filters, one of which is preferably a mismatched filter. In another aspect of the invention, a repeated codeword preamble is formed from a series of the same repeated short subcode. The short subcode may be an augmented or truncated odd-length code. At the receiver a single matched filter is preferably used to generate a series of spikes separated by the period of the subcode. An alert/confirm detector non-coherently adds together individual correlation spikes and reject false alarms.

Abstract: A computer program for a user in a wireless communication system to communicate on the system. The communication protocol embodied in the computer program enables the user to acquire a channel on a base station in the system and register with a base station on the system. The communication protocol embodied in the computer program also enables the user to place and receive calls on the communication system. The computer program is comprised of a main controller task and various other tasks, also called subtasks, which are activated by the main controller task. These subtasks are each designed to perform a protocol function for the user on the communication system.

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams (such as I and Q data streams), independently modulates the I and Q data streams using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and simultaneously attempts to correlate for a plurality of chip sequences (such as I and Q chip sequences), and interleaves the correlated I and Q data streams into a unified signal data stream. In one embodiment, the receiver separates the received spread spectrum signal into real and imaginary parts, attempts to correlate both real and imaginary parts for a plurality of chip sequences, and combines the real I, real Q, imaginary I, and imaginary Q signals into a unified signal data stream.

Abstract: A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of which the base station transmits to a user station and the user station transmits to the base station. Communication is initiated by a round trip timing transaction. In response to a general polling message from the base station, a user station seeking to establish communication transmits a short reply message. The base station calculates the distance of the user station by measuring the propagation delay with respect to receipt of the reply message. The base station sends a timing adjustment command to the user station instructing the user station to advance or retard its timing according to the calculated distance, so as to minimize guard times between time slots.

Abstract: A spread spectrum receiver for demodulating a CPM spread spectrum signal receives burst comprising a preamble and a data message that have been transmitted by M-ary encoding of a data signal into a single chip stream, dividing the chip stream into I and Q signal streams, independently modulating the I and Q signal streams, and superposing the resultants for transmission. The receiver detects the preamble using a non-coherent parallel correlator, and from the preamble correlation peak generates a series of integration periods for serial non-coherent correlation. A bank of non-coherent, serial correlators operate in parallel to recover the spread spectrum encoded information.

Abstract: Systems and methods for locating a remote station within an area of a wireless communications network without using a global positioning system. Communications are established between a remote station and a plurality of base stations using separate time slots within at least one over-the-air loop. Propagation delay times associated with signals transmitted or received within the time slots are determined, and one or more possible locations of the remote station are identified based upon the determined propagation delay times.

Abstract: 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.