Lucent Technologies Inc.

Motorola Corporation

At+t Corp.

Joseph Boccuzzi

Clinton C Powell, Ii

Muzibul H Khan

Paul Petrus

Winston Hong Lieu

A signal processor ( ) for recovering data symbols from a received signal includes matched filters ( ) for receiving and filtering a quadrature (Q) signal component of the received signal. A detector ( ) is coupled to the matched filters ( ) for selecting a filtered signal provided by one of the matched filters ( ) and for labeling the filtered signal according to a magnitude and phase of the filtered signal to provide a Q channel output flag. A Q channel symbol/sign decoder ( ) then processes the Q channel output flag to generate a Q channel magnitude variable and a polarity variable, and a symbol decoder ( ) coupled to the Q channel symbol/sign decoder ( ) generates a data symbol in accordance with the Q channel magnitude variable and the polarity variable.

Method and apparatus for recovering data symbols from a signal received by a radio communication device

A method for automatic frequency control in a wireless communication network having public frequency channels comprises the steps of: scanning the public frequency channels; locking the cellular base station to a signal on one of the public frequency channels; and returning the cellular base station to normal operation.

Automatic frequency control for a cellular base station

In a communication network, a method for channel quality estimation, without the need for a reference (uncorrupted) signal, comprises the steps of: processing a received signal utilizing a non-redundant error correction scheme to observe at least one symbol; producing an error signal in response to the observation; and counting a quantity of the error signal during a predetermined time interval to provide a symbol error count. A device for channel quality estimation, without the need for a reference (uncorrupted) signal, is also described.

Channel quality estimator based on non-redundant error correction

A method and apparatus for a portable communication device, such as a mobile radio terminal in a CDMA network, to identify its geographic location. A communication network comprises multiple base stations which transmit pilot signals, where the pilot signals of one base station are offset from the pilot signals of other base stations by integral multiples of a substantially fixed duration. Associated sync channel messages are also transmitted from which the geographic location of the base stations may be extracted. A portable communication device identifies its location by calculating the delay between the arrival time of a pilot signal from a primary base station and the arrival times of pilot signals from at least two other base stations. For each pair of base stations corresponding to one of the calculated delays, the portable communication device initially specifies its location as being on a selected one of three curves. The current location of the portable communication device is identified based upon points of intersection of the selected curves. The identified location may be stored in, transmitted from, or displayed at the portable communication device.

Method and apparatus for a portable communication device to identify its

A reduced complexity maximum likelihood multiple symbol differential detector which utilizes a maximum likelihood sequence estimation of the transmitted phase and does so by expanding the observation window to observe the received symbol over N signal intervals and making a simultaneous decision on N-1 symbols. The phase of the received signal is calculated up front and thus the detector requires only real subtractions and real additions as opposed to complex multiplications and additions. Furthermore, the detector does not sacrifice performance over conventional prior art detectors.

Reduced complexity maximum likelihood multiple symbol differential

A radio communication device (100) for recovering information from a received signal includes a demodulator (110) for demodulating the received signal into in-phase (I) and quadrature (Q) components and a multiplier (115) for multiplying the I and Q components together to generate a multiplied waveform. A polarity detector (125) coupled to the multiplier (115) determines from the multiplied waveform a polarity variable indicative of a data symbol, and a processor (135) recovers the information from the received signal in accordance with the data symbol.

Method and apparatus for information recovery in a radio communication

A .pi./4 delay spread detection and compensation arrangement effectively detects distortion due to multipath delay spread in a digital channel and compensates for this distortion with minimum circuit complexity. An improvement in the bit error rate performance for a differential detector in the receiver is achieved through use of a detected direct current (DC) component, which is proportional to the amount of multipath delay spread on the digital channel. This DC component is used in the differential detector for compensating for this delay spread. In addition, the differential detector also provides a channel quality measure of the level of delay spread on the digital channel for use by the receiver in selecting either the differential detector or an equalizer for decoding of the data on the digital channel. When the level of delay spread is low, a processor used by the equalizer is freed for other computational tasks or, when the bit error rate permits, is not used at all thereby realizing a reduction in power consumption in the receiver.

.pi./4-DQPSK delay spread detection and compensation apparatus and method

A technique of demodulating a .pi./4-DQPSK composite carrier waveform using a non-coherent discriminator based receiver is presented. In particular, a means of recovering .pi./4-DQPSK modulated data symbols using a dual output discriminator in conjunction with a dual binary amplitude detection process in a discriminator based receiver is discussed. Means which improve the bit error rate of the receiver over the prior art are presented. Additionally, an amplitude detection means which readily provides synchronization of the detected data symbols is discussed which was not heretofore possible with the 4-level slicer of the prior art.

Robust non-coherent detector for .pi./4-DQPSK signals

A .pi./4-DQPSK differential phase state encoder/decoder (Codec) is presented which can be implemented using a small number of logic gates. The phase state Codec acts upon data in the transmitter and in the receiver of a .pi./4-DQPSK modulating system whereby the use of a look-up table technique or other off-line procedure to ensure proper phase transitions is not required. The phase state Codec is configured to ensure compliance with the IS-54 standard as well as other similar standards.

PI/4-DQPSK phase state encoder/decoder

Briefly, according to the invention, a receiver (100) for receiving a carrier signal MSK (minimum shift keying) modulated with a bit stream of a digital information signal (302) is disclosed. The receiver (100) comprises a quadrature demodulator (128) for providing baseband quadrature demodulated signals (306 and 308). The quadrature demodulated (128) is coupled to an EXOR (126) for providing a decoded bit stream of the digital information signal (312) thereby avoiding complex decoder circuits. The quadrature demodulator (128) includes a pair of mixers (106 and 108) for quadrature mixing the received carrier signal and a pair of filters (114 and 118) for filtering the outputs of the mixers (106 and 108). The filters (114 and 118) are coupled to a pair of limiters (116 and 120) for limiting the filtered signals.

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Brooklyn, NY, United States of America

Joseph Boccuzzi