Motorola Corporation

Racal Data Communications Inc.

Thomas A Sexton

Fuyun Ling

Eugene J Bruckert

Robert T Love

Kenneth Anderson Stewart

Steven Jeffrey Goldberg

Thomas Casey Hill

Stephen Rocco Carsello

Robert L Breeden

Charles J Malek

James A McDonald

Brian J Budnik

William R Bayer

William F Pickert

Gene Bruckert

James J Womack

In a communication system where a continuous reverse channel transmission is utilized by redundant transmission of Walsh codes, a current transmission rate is modulated onto Walsh code polarity. In particular, a remote unit operating at a particular transmission rate utilizing a continuous reverse channel transmission modulates the transmission rate by setting the polarity of each Walsh code depending upon the current or future data traffic channel rate. In communication systems where a Reference Coherent (RC) type transmission is utilized, the particular transmission rate is modulated onto the reference symbols (501-517) by setting the reference symbols (501-517) equal to a binary '1' or '0'.

Method and apparatus for transmission and reception of a transmission

In a messaging system having a plurality of simulcasting base transmitters (104), a plurality of pseudorandom sequence generators (216) are provided (402) for the plurality of base transmitters. The plurality of pseudorandom sequence generators are arranged (403) to ensure that they generate a plurality of pseudorandom sequences having sub-sequences that are different from one another during concurrent transmissions by the plurality of base transmitters. A cancellation-affecting parameter of the plurality of base transmitters is adjusted (404, 406, 408) in accordance with the plurality of pseudorandom sequences during the simulcast transmission from the plurality of base transmitters to limit intervals of carrier cancellation.

Method and apparatus in a messaging system for limiting an interval of

A fixed portion (102) of a radio messaging system schedules (602) an inbound message to be transmitted at a first scheduled time on a channel from a portable subscriber unit (122). The channel is monitored (604) at the first scheduled time to receive the inbound message, utilizing a beamforming technique. In response to failing to achieve adequate reception of the inbound message at the first scheduled time, the fixed portion reschedules (608) the inbound message to be transmitted at a second scheduled time, and remonitors (610) the channel at the second scheduled time to receive the inbound message, utilizing an omnidirectional technique.

Method and apparatus for adjusting inbound transmission reliability in a

The method includes acquiring a signal (501); inputting (502), at a first time, a received symbol to a demodulator having a plurality of outputs to produce a set of early outputs; inputting (504), at a second time, the received symbol to the demodulator to produce a set of on-time outputs; inputting (505), at a third time, the received symbol to the demodulator to produce a set of late outputs; and comparing (506) at least one output in the set of early outputs with at least one output in the set of late outputs to produce a timing measure.

Method for receiving a signal in a digital radio frequency communication

The method includes receiving a signal comprising a received frame, the received frame having a plurality of received symbols and having a received information portion and a received frame quality indicator; storing at least one of the plurality of received symbols in a memory; demodulating the received information portion to form a demodulated information portion and demodulating the received frame quality indicator to form a demodulated frame quality indicator, the demodulated information portion and the demodulated frame quality indicator comprising a demodulated frame; re-encoding at least a portion of the demodulated frame to form an encoded frame, the encoded frame having a plurality of encoded symbols; comparing one of the plurality of encoded symbols with the at least one of the plurality of received symbols stored in the memory; and based on the comparison, estimating the channel parameter.

Radiotelephone communication unit displaying chronological information

A method for transmitting a communication signal (20) having a data rate over a plurality of spread spectrum traffic channels includes determining a first number of traffic channels required to transmit the communication signal at the data rate, and determining a second number of traffic channels (502) available for transmitting the communication signal (20). In response to a comparison of the first number of traffic channels to the second number of traffic channels, a first traffic channel (54) for transmitting a first portion of the communication signal (50, 51) and a second traffic channel (56) for transmitting a second portion of the communication signal (52, 53) are selected from the. second number of traffic channels (502). The selection of the first traffic channel (54) is non deterministic of the selection of the second traffic channel (56).

Method and system for communication over multiple channels in a spread

Power control in a spread spectrum communication system takes place by determining a speed of a remote unit (405) and assigning as a power-control threshold a target threshold based on the determined speed (410). An instantaneous threshold value is created (415) based on frame-quality information and the target threshold. An energy of a power-control group transmitted (430) from a remote unit is compared to the instantaneous threshold value and a power-adjustment command is determined. The power-adjustment command is transmitted to the remote unit instructing the remote unit to adjust its power accordingly.

Method and apparatus for power control in a communication system

A receiver (200, 400) implements improved channel estimation. The receiver (200, 400) demodulates a transmitted signal, and makes an initial channel estimate (115). The receiver (200, 400) then makes a hard decision (301) as to whether the channel estimate was correct and groups samples representing the decision. A vector sum of the group of samples is computed (302), and each sample is compared to the vector sum (303). The sample having the largest projection on the vector sum is retained (304), and the other samples are considered noise, and are thus discarded (305). After obtaining a predetermined number of retained samples (306), the retained samples are used to generate an new channel estimate (226). Since the noisy estimates are discarded, the new channel estimate (226) contains fewer errors than the initial channel estimate (115). The new channel estimate (226) is used to generate decoded data (250).

Channel estimation in a communication system

A method and apparatus for improved offset frequency estimation includes in a first embodiment a receiver (100) for coherent reception of a signal having known reference information, the receiver including an extractor (106) for extracting the reference information (107) from the signal, and an offset frequency estimator (110). The offset frequency estimator (110) includes a filter (121) for filtering the reference information and outputting a filtered reference sequence; a correlator (122, 124) for correlating the filtered reference sequence against a predetermined reference signal to form correlation values; and a peak detector (126) for determining an offset frequency estimate (131) from the correlation values. Other embodiments are also shown.

Method and apparatus for offset frequency estimation for a coherent

A method and apparatus is provided for facilitating coherent communication reception. A received reference symbol coded spread spectrum communication signal is despread with a spreading code to derive a stream of reference samples and a stream of data samples. The channel response is estimated by utilizing the stream of reference samples. An offset frequency detector determines an offset to be applied to the received signal via a frequency locked loop, while a timing control compensates for slow timing drift and fast fading based on power estimates derived from the stream of reference samples and/or the stream of data samples. A rate estimator determines the rate at which the information was encoded, and the rate information is used to optimize the timing control, frequency offset detector and channel estimator. Thus an improved detection of estimated data symbols from the stream of received data samples is provided.

Method and apparatus for coherent communication reception in a

In frequency-hopping spread-spectrum systems, it is necessary to maintain frequency and bit synchronization (sync) between the transmitter and receiver in order to maintain quality data recovery at the receiver. A protocol is described which includes a synthesizer lock field (109) to allow frequency sync, a clock sync field (123) to achieve quick clock sync, and a data sync field (125) to provide data sync. Other fields are provided in the protocol to allow both voice (141) and data (127) transmissions, inband signalling (139), and error correction (143). A method and apparatus, driven by a microprocessor (303) and ASIC (301) combination, are described that generate and transmit this protocol.

Digital communication signalling system

A method for estimating an amount of phase roll on a transmission channel. A signal of known frequency is transmitted over the channel by a near end modem. An average noise autocorrelation matrix is subtracted from an average signal plus noise autocorrelation matrix, both as received by a near end modem. The eigenvector of the resulting matrix is computed. The complex root of a quadratic with coefficients equal to the eigenvector elements is computed to solve for a difference between the frequency of the transmitted signal and the echoed receive signal to determine the phase roll.

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Schaumburg, IL, United States of America

Thomas A Sexton