Motorola Corporation

Leo George Dehner

Weizhong Chen

Slim S Souissi

Stephen Rocco Carsello

Eric F Meihofer

Kevin Lynn Baum

Thomas Casey Hill

Richard A Comroe

Charles W Bethards

Phillip D Neumiller

James Wesley McCoy

Spread spectrum packet-switching radio devices () are operated in two or more ad-hoc networks or pico-networks () that share frequency-hopping channel and time slots that may collide. The frequency hopping sequences () of two or more masters () are exchanged using identity codes, permitting the devices to anticipate collision time slots (). Priorities are assigned to the simultaneously operating piconets () during collision slots (), e.g., as a function of their message queue size or latency, or other factors. Lower priority devices may abstain from transmitting during predicted collision slots (), and/or a higher priority device may employ enhanced transmission resources during those slots, such as higher error correction levels, or various combinations of abstinence and error correction may be applied. Collisions are avoided or the higher priority piconet () is made likely to prevail in a collision.

Multiple access frequency hopping network with interference anticipation

A method and apparatus for facilitating handoff from a network access point (NAP) that is arranged and constructed to provide service to a communications unit (CU) in a frequency hopped communications system. The operations that are performed are providing service between the CU and the NAP on a connection using a first frequency hopping pattern (FHP); determining that the connection is suitable for discontinuation based on RSSI or load; sending a first message including an ID for the NAP and schedule for the CU to neighboring NAPS, the message requesting assistance with the service on tho first FHP; and receiving a second message from a neighboring NAP, arranged and constructed to provide connections to CUs using a second FHP, the second message indicating that assistance can be provided by the neighboring NAP.

Method and apparatus for facilitating handoff in a wireless local area network

A synchronization signal includes a plurality of predetermined synchronization symbols shaped by a predetermined symbol pulse. A receiver ( ) receives ( ) a signal including the synchronization signal, and a processor ( )determines ( ) a first plurality of cross-correlations between the predetermined symbol pulse and the received signal. The processor calculates ( ) a plurality of sums of products of the plurality of predetermined synchronization symbols and a predetermined subset of the first plurality of cross-correlations. The plurality of sums are mathematically equivalent to a second plurality of cross-correlations between the synchronization signal and the received signal. The processor locates ( ) a peak of the plurality of sums to establish receiver synchronization.

Method and apparatus for establishing synchronization with a synchronization signal

A receiver ( ) receives ( ) a first signal including a sync portion ( ) having a carrier acquisition segment ( ) and a timing synchronization pattern ( ), and a processing system ( ) of the receiver calculates ( ) a first plurality of squared magnitude Fourier transforms at a first plurality of frequencies on the carrier acquisition segment. The processing system derives ( ) an initial carrier frequency error estimate by locating a peak in the first plurality of squared magnitude Fourier transforms, and corrects ( ) the sync portion according to the initial carrier frequency error estimate, thereby producing a carrier-corrected sync portion. The processing system then removes ( ) the timing synchronization pattern from the carrier-corrected sync portion, thereby producing a second signal having a residual carrier error.

Method and apparatus for facilitating an estimation of a carrier frequency error in a receiver of a wireless communication system

A processor ( ) is assigned a predetermined synchronization signal for use in communicating in a wireless communication system ( ) The processor calculates ( ) a total energy of the predetermined synchronization signal. A receiver front end ( ) coupled to the processor receives ( ) a signal which may include the predetermined synchronization signal, and calculates ( ) a plurality of cross-correlation values between the received signal and the predetermined synchronization signal to locate a correlation peak. The processor also calculates ( ) a plurality of detection metrics as a function of the plurality of cross-correlation values, the received signal, and the predetermined synchronization signal. In addition, the processor calculates ( ) a corresponding plurality of adaptive thresholds as a function of the total energy and the received signal, and compares ( ) the plurality of detection metrics with the plurality of adaptive thresholds to determine whether the received signal includes the predetermined synchronization signal.

Method and apparatus in a wireless communication system for facilitating detection of, and synchronization with, a predetermined synchronization signal

A processor (,) receives an input signal including symbols for transmission, and determines an output signal for a symbol period from a predetermined range of symbols of the input signal in combination with a modulating phasor vector and a matrix of filter coefficients. The processor compares samples of the output signal with a predetermined amplitude limit; and, in response to a sample of the output signal exceeding the predetermined amplitude limit, adjusts the symbols of the predetermined range of symbols that are not pilot symbols by an adjustment factor, thereby creating a new input signal. If a sample of the output signal exceeds the predetermined amplitude limit, the processor computes a new output signal from the new input signal in combination with the modulating phasor vector and the matrix of filter coefficients; and generates a power-controlled modulated radio signal from the new output signal.

Method and apparatus for power control in a transmitter

A first master transceiver (,) of a first wireless network monitors (,) neighboring wireless networks to discover a strongest interfering master transceiver in one of the neighboring wireless networks. The first master transceiver then time-aligns (,) hop intervals of the first master transceiver with the hop intervals of the strongest interfering master transceiver to ensure that a transmission of the strongest interfering master transceiver during each hop interval used by the strongest interfering master transceiver cannot interfere with the transmission of the first master transceiver during more than one hop interval of the first master transceiver, thereby minimizing the probability of self-interference between the first wireless network and the one of the neighboring wireless networks.

Method and apparatus for minimizing a probability of self-interference among neighboring wireless networks

A communication receiver (300) receives (404) a modulated signal, and demodulates the modulated signal to recover a timing signal (202) and a data signal (204) including data symbols. A processing system (316) of the communication receiver determines (406) a rough symbol timing from the timing signal, and forms (408) a timing-carrier search matrix by computing signal quality metrics from the data symbols as a function of predetermined trial variations of the carrier frequency about a nominal carrier frequency and as a function of predetermined trial variations of the symbol timing about the rough symbol timing. The processing system then estimates (410) the symbol timing and the carrier frequency by locating a minimum one of the plurality of signal quality metrics in the timing-carrier search matrix.

Method and apparatus in a communication receiver for estimating symbol

A digital sync signal (502) is transmitted (702) from K transmitters (206) of a cluster (402), followed by K fine tuning signals (506) during K time slots (510), each time slot assigned to a transmitter. Each fine tuning signal comprises a pair of tones (512) separated in frequency by a predetermined amount. A portable subscriber unit (122) receives (706) the sync signal and the fine tuning signals, and makes (708) a rough estimate of the beginning of the fine tuning signals from the sync signal and from knowledge about the time slots. The portable subscriber unit computes (710) for each time slot a 2M-point Fourier transform (FT) on a received signal including M fine tuning signals received during the time slot from a transmitter of the cluster and from M-1 corresponding transmitters of adjacent clusters (404). The portable subscriber unit then fine tunes (722) the rough estimate through FT calculations.

Method and apparatus for facilitating establishment of communications in

A method and apparatus samples (902) a currently received symbol to form sampled values corresponding to sampling times, and evaluates (904) the currently received symbol to determine (906) its value. The method and apparatus recalls (908) a last previously received symbol and selects (916), from a plurality of thresholds (302), a threshold based upon the currently received symbol and the last previously received symbol. The threshold is known to be crossed consistently midway in time between the centers of two adjacent nominal symbols determined by the currently received symbol and the last previously received symbol. The sampled values are compared (920) to locate two adjacent samples, one having a first sampled value greater than the threshold and one having a second sampled value less than or equal to the threshold. A timing phase error is then computed (922, 924) from the first and second sampled values.

Method and apparatus for facilitating symbol timing acquisition in a

A radio communication system (100) implements a frequency reuse plan by sending a message (308) simultaneously with other messages in a plurality of cell clusters (202-208) utilizing the frequency reuse plan, which provides a message carrier-to-interference ratio (C/I) sufficient for reception of the message when a receiver (104) is adjusted in accordance with a periodically transmitted pilot symbol (402-408). The C/I is smaller than preferred for reception of the pilot symbol. The pilot symbol is periodically transmitting simultaneously with other pilot symbols in a time diverse manner such that pilot symbol transmissions for adjacent ones of the plurality of cell clusters occur in non-overlapping time slots, thereby generating the larger C/I preferred for reception of the pilot symbol. The pilot symbol and the message are received by the receiver, and the receiver is adjusted in accordance with the pilot symbol to demodulate the message.

Method and apparatus in a radio communication system for implementing a

A receiver (109) and a method therein arranged and constructed to receive a signal using a noncoherent matched filter structure including a frequency detector (205) arranged to process a first portion (602) of the signal to provide a frequency error; a timing detector (206), responsive to the frequency error, arranged to process a second portion (604) of the signal to provide a timing error; and a symbol detector (209), responsive to the frequency error and the timing error, arranged to process a symbol portion (606) of the signal to provide a detected symbol.

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Southlake, TX, United States of America

Leo George Dehner