Sbc Technology Resources, Inc.

At&t Intellectual Property I, L.p.

At&t Mobility Ii LLC

Sbc Knowledge Ventures, L.p.

At&t Labs, Inc.

Richard A Kobylinski

David R Wolter

Milap V Majmundar

Ayman A Mostafa

Arunhaba Ghosh

Arunabha Ghosh

David Randall Wolter

A technique includes jointly demodulating a desired signal and an interfering signal of a received signal in response to a carrier-to-interference ratio estimate for the received signal being below a threshold level. The jointly demodulating is based on first channel impulse response coefficients associated with the desired signal and second channel impulse response coefficients associated with the interfering signal. The technique includes determining the first channel impulse response coefficients based on a first cross-correlation function between the received signal and a training sequence of the desired signal and determining the second channel impulse response coefficients based on a second cross-correlation function between the received signal and a training sequence of the interfering signal. The second channel impulse response coefficients are determined based on a time difference between a time value of a peak in the first cross-correlation function and a time value of a peak in the second cross-correlation function.

Joint demodulation of a desired signal and an interfering signal based on a carrier-to-interference ratio estimate

A technique includes performing non-joint demodulation of a desired signal in response to a carrier-to-interference ratio estimate for a received signal being greater than or equal to a threshold level, the non-joint demodulating being based on first channel impulse response coefficients associated with the desired signal and second channel impulse response coefficients associated with one or more interfering signals. The technique includes determining the second channel impulse response coefficients based on a first cross-correlation function between the received signal and a training sequence of an interfering signal of the one or more interfering signals, determining the first channel impulse response coefficients based on a second cross-correlation function between the received signal and a training sequence of the interfering signal, and determining a time difference between a time value of a peak in the first cross-correlation function and a time value of a peak in the second cross-correlation function.

Non-joint demodulation of a desired signal in response to a carrier-to-interference ratio estimate

Systems and methods for performing joint demodulation using a Viterbi equalizer having an adaptive total number of states are disclosed. Generally, a method includes joint demodulating a desired signal and one or more interfering signals with a Viterbi equalizer having an adaptive total number of states based on channel impulse response (CIR) coefficients associated with a desired signal and the one or more interfering signals.

Joint demodulation using a viterbi equalizer having an adaptive total number of states

Systems and methods for performing joint demodulation using a Viterbi equalizer having an adaptive total number of states are disclosed. Generally, a method includes joint demodulating a desired signal and none or more interfering signals with a Viterbi equalizer having an adaptive total number of states based on channel impulse response (CIR) coefficients associated with a desired signal and the one or more interfering signals.

Joint demodulation using a Viterbi equalizer having an adaptive total number of states

A combined SAIC receiver and a multiple-antenna, receive diversity receiver are employed to reduce interference in a wireless system. The real and imaginary parts of the de-rotated signal for each receive path associated with an antenna are separately filtered and a combined output signal of all receive paths is generated. The weighting coefficients are adjusted based on an error signal produced by comparing the combined output signal with a reference signal. The weighting coefficients are initially set based on an MMSE/LS type of signal processing criteria, where the reference signal is the Training Sequence Code (TSC). Subsequent adjustment/tracking can be accomplished by using known tracking algorithms, e.g. LMS or RLS, or the coefficients can be re-computed using MMSE/LS processing. The reference signal for tracking may be a combination of the TSC and estimated data symbols provided by an equalizer.

Interference cancellation and receive diversity for single-valued modulation receivers

Systems and methods for performing joint demodulation using a Viterbi equalizer having an adaptive total number of states are disclosed. Generally, a method includes joint demodulating a desired signal and none or more interfering signals with a Viterbi equalizer having an adaptive total number of states based on channel impulse response (CIR) coefficients associated with a desired signal ant the one or more interfering signals.

First and second partially collapsed metric values are determined for each bit in a symbol transition. Each first partially collapsed metric value is a cumulative metric of starting in a first state and ending in a second state in L transitions with the respective bit in the symbol transition being a first value. Each second partially collapsed metric value is a cumulative metric of starting in the first state and ending in the second state in L transitions with the respective bit in the symbol transition being a second value, the second value differing from the first value. For each bit in the symbol transition, a relative likelihood value is determined based on its respective first and second partially collapsed metric values. A symbol is decoded based on a hard decision performed using the relative likelihood value for each bit in the symbol transition.

Soft bit viterbi equalizer using partially collapsed metrics

A desired signal and at least one interfering signal are joint demodulated with a Viterbi equalizer having an adaptive total number of states. The total number of states is based on channel impulse response (CIR) coefficients associated with the desired signal and the at least one interfering signal.

A system and method for improved mobile assisted handoff in a digital cellular communication system that gives the mobile station the ability to synchronize to candidate base station transmissions in order to read the transmitted digital voice color code (DVCC) of the candidate station. This process is performed during the idle period between two designated time slots in a TDMA frame. The invention is an enhancement to the existing mobile assisted handoff procedures described in the existing IS-136 standard. The present invention improves on the IS-136 standard's use of received signal strength measurements in that it allows the mobile station to acquire and report information regarding the digital verification color code (DVCC) of the candidate base station channels. Since the DVCC uniquely identifies the cell site to which a channel belongs, it is used to distinguish the candidate base station channel from its co-channel interferers, allowing the network to make a more informed handoff decision.

Mobile assisted handoff system and method

A system and method for improved mobile assisted handoff in a digital cellular communication system that gives the mobile station the ability to synchronize to candidate base station transmissions in order to read the transmitted digital voice color code (DVCC) of the candidate station. This process-is performed during the idle period between two designated time slots in a TDMA frame. The invention is an enhancement to the existing mobile assisted handoff procedures described in the existing IS-136 standard. The present invention improves on the IS-136 standard's use of received signal strength measurements in that it allows the mobile station to acquire and report information regarding the digital verification color code (DVCC) of the candidate base station channels. Since the DVCC uniquely identifies the cell site to which a channel belongs, it is used to distinguish the candidate base station channel from its co-channel interferers, allowing the network to make a more informed handoff decision.

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Austin, TX, United States of America

Richard A Kobylinski