System and method for providing an accurate estimation of received signal interference for use in wireless communications systems

A system for providing an accurate carrier signal-to-interference ratio for facilitating the decoding of a signal received over a channel, the system comprising:

• means for receiving a signal over a channel, said received signal comprising one or more chips;
• means for providing an estimate of total received energy of each of said one or more chips, said estimate of total received energy having an interference component and a desired signal energy component;
• means for extracting from said received signal an estimate of said desired signal energy component;
• means for employing said estimate of said desired signal energy component and said estimate of total received energy to provide an estimate of said interference component;
• and
• means for using said estimate of said desired signal energy component and said estimate of said interference component to provide said accurate carrier signal-to-interference ratio.

A system for providing optimal inputs to a log-likelihood ratio computer, the system comprising:

• a first receiver for receiving a signal over a channel;
• an interference calculator for providing a signal representative of interference or noise contained in said received signal and providing a signal-to-interference ratio in response thereto;
• an optimal path combiner for employing said signal representative of interference or noise and said received signal to produce an optimal path-combining signal as a first optimal input to said log-likelihood ratio computer;
• and
• an accumulator for accumulating said signal-to-interference ratio to provide an optimal carrier signal-to-interference value as a second optimal input to said log-likelihood ratio computer.

A communications system comprising:

• a transceiver for transmitting a first signal over a channel at a predetermined rate and power level, said channel introducing noise or interference to said first signal;
• means for receiving said first signal and providing in-phase and quadrature samples of said first signal in response thereto, said first signal having a pilot signal component and one or more multipath components;
• means for extracting said pilot signal and providing an estimate of total interference energy received via said first signal on a predetermined multipath component based on said pilot signal component and said in-phase and said quadrature samples;
• means for generating a power or rate control signal based on said estimate of total interference energy and an estimate of energy associated with said one or more multipath components;
• means for transmitting said power or rate control signal to said transceiver;
• means for computing optimal path-combining weights for said one or more multipath components based on said estimate of total interference energy and providing optimally combined signal paths in response thereto;
• and
• means for computing a log-likelihood value based on said optimally combined signal paths, said total interference energy, and said estimate of energy associated with said one or more multipath components;
• and
• means for decoding said first signal in response to said log-likelihood value.

A path weighting and combining circuit for determining maximal ratio path-combining weights for multiple paths of a received signal that has an interference component, a data component, and a pilot signal component comprising:

• a separating circuit for separating said pilot signal component and said data component from said received signal;
• a pilot filter for filtering said pilot signal to yield a filtered pilot signal;
• an interference estimation circuit for estimating said interference component and providing an interference value in response thereto;
• a first multiplier for multiplying said filtered pilot signal by a predetermined constant scaling factor and providing a scaled value in response thereto;
• a second multiplier for multiplying said scaled value by a reciprocal of said interference value to yield a weighted signal;
• and
• a conjugation circuit for computing a conjugate of said weighted signal to yield maximal ratio weights in response thereto.

A method for providing an accurate noise or interference value for a signal received over a channel and transmitted by an external receiver comprising the steps for:

• receiving said signal, said received signal having a desired signal component and an interference or noise component;
• extracting an estimate of said desired signal component from said received signal;
• and
• providing said accurate noise or interference value based on said estimate of said desired signal component and said received signal.

A system comprising:

• a code division multiple access (CDMA) receiver capable of receiving a signal over a wireless channel, the received signal comprising a desired signal component and an interference component;
• a carrier signal-to-interference and interference energy estimator connected to the CDMA receiver to generate an interference energy value and a signal-to-interference ratio of the received signal, the carrier signal-to-interference and interference energy estimator comprising a signal extractor to extract an estimate of the desired signal component from the received signal;
• and
• a path combiner connected to the signal extractor to generate summed weighted-path signals in response to the interference energy value and the estimate of the-desired signal component.

A system comprising:

• a code division multiple access (CDMA) receiver capable of receiving signals over a wireless channel, the received signals comprising a pilot signal and data signals;
• a carrier signal-to-interference and interference energy estimator connected to the CDMA receiver to generate an interference energy value and a signal-to-interference ratio of the received signals, the carrier signal-to-interference and interference energy estimator comprising:
• a pilot fingers filter capable of receiving a despread and decovered pilot signal and in response generating a filtered pilot signal;
• a pilot energy computer connected to the pilot fingers filter to generate a pilot energy value p2;
• a look-up table connected to the pilot energy computer to generate a result equal to 1/(1−p2);
• and
• a carrier signal-to-interference path accumulator connected to the look-up table to generate an estimate of a total multi-path carrier signal-to-interference ratio;
• and
• a path combiner connected to the carrier signal-to-interference and interference energy estimator to generate summed weighted-path signals comprising in-phase summed weighted-path components and quadrature summed weighted-path:
• components.

A system comprising:

• a code division multiple access (CDMA) receiver capable of receiving signals over a wireless channel and in response generating spread-spectrum in-phase and quadrature signals, the received signals comprising a pilot signal and data signals;
• an interference energy estimator connected to the CDMA receiver to generate an interference energy value of the received signals, the interference energy estimator comprising:
• a pseudo-noise despreader capable of generating despread in-phase and quadrature signals in response to the spread-spectrum in-phase and quadrature signals;
• a decoverer connected to the pseudo-noise despreader to separate the data signals along a data channel and the pilot signal along a pilot channel from the despread in-phase and quadrature signals;
• a pilot filter connected to the pilot channel to generate a filtered pilot signal;
• a pilot subtractor connected to subtract the pilot signal transmitted along the pilot channel from the filtered pilot signal to generate a signal representative of interference and noise per symbol;
• and
• an interference energy computer connected to the pilot subtractor to generate an interference energy value;
• and
• a path combiner connected to the interference energy estimator to generate summed weighted-path signals based on the interference energy value and the data signals from the data channel.