Two step signal recovery scheme for a receiver
AssigneeLSI Logic Corporation
InventorBrian C. Banister
Life of this patent
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Abstract
According to an embodiment of the invention, a DS-CDMA receiver receives an input signal which comprises a plurality of received signals that are received over a corresponding plurality of antennae. These signals are demodulated and sampled to create digital signals. The digital signals are decorrelated and each of the decorrelated signals are multiplied by a weight to derive weighted estimates. The weighted estimates are summed to generate an estimate of an information symbol. The weights are based upon a cross correlation between the decorrelated signals and a desired signal. According to the invention, this cross correlation may be derived by filtering a pilot signal.
Claims45
A method for recovering from a signal estimates of information symbols for at least two receive paths, the signal being transmitted through a channel with a response, the method comprising the steps of:
- (A) receiving an input signal;
- (B) at least partially decorrelating the input signal to derive a decorrelated version of the input signal;
- (C) deriving a plurality of weights based upon a cross correlation between the decorrelated version and a desired signal that contains an information symbol for the first receive path;
- (D) processing a version of the decorrelated version with information that is specific to a first receive path including multiplying the decorrelated version by the weights to recover an estimate of the information symbol for the first receive path;
- and
- (E) processing a version of the decorrelated version with information that is specific to a second receive path to recover an estimate of an information symbol for the second receive path.
A method for recovering from a signal estimates of information symbols for at least two receive paths, the signal being transmitted through a channel, the method comprising the steps of:
- (A) receiving an input signal represented as a vector before with a plurality of elements each equal to a complex baseband of a portion of the input signal;
- (B) generating a decorrelation matrix G−½ that is a Cholesky decomposition of an estimate of a correlation matrix of the input signal;
- (C) multiplying the vector ubefore by the decorrelation matrix G−½ to derive a decorrelated version of the input signal;
- (D) processing a version of the decorrelated version with information that is specific to a first receive path to recover an estimate of an information symbol for the first receive path;
- and
- (E) processing a version of the decorrelated version with information that is specific to a second receive path to recover an estimate of an information symbol for the second receive path.
A method for recovering an estimate of an information symbol transmitted as part of an input signal, the method comprising the steps of:
- (A) receiving the input signal comprising a plurality of received signals;
- (B) at least partially decorrelating the received signals to create a plurality of decorrelated signals;
- (C) generating a plurality of weights including multiplying a version of at least one of the decorrelated signals by a desired signal that contains the information symbol;
- (D) multiplying a version of each of the received signals by a corresponding one of the weights to create a plurality of weighted estimates;
- and
- (E) adding together the weighted estimates to derive an estimate of the information symbol.
A method for recovering an estimate of a particular information symbol from an input signal that includes other information symbols that interfere with the particular information symbol, the method comprising the steps of:
- (A) receiving the input signal;
- (B) deriving a decorrelation matrix for a time interval n based upon a past decorrelation matrix for a time interval prior to n;
- (C) applying the decorrelation matrix for the time interval n to a version of the input signal to create a plurality of signals uncorrelated from one another;
- (D) deriving a plurality of weights;
- (E) multiplying a version of each of the decorrelated signals by a corresponding one of the weights to create a plurality of estimates;
- and
- (F) adding together the plurality of estimates to obtain an estimate of the information symbol.
A method for recovering an estimate of an information symbol transmitted as part of an input signal, the method comprising the steps of:
- (A) receiving a plurality of received signals over a corresponding plurality of antennae, each of the received signals being encoded such that one information symbol corresponds to a plurality of transmitted symbols;
- (B) decoding a version of each of the received signals to create a corresponding plurality of initial symbol estimates;
- (C) generating a plurality of weights from the received signals based upon a cross correlation between a decorrelated version of the received signals and a desired signal that contains the information symbol;
- (D) multiplying each of the initial symbol estimates by a corresponding one of the weights to create a plurality of weighted estimates;
- and
- (E) adding together the weighted estimates.
A method for recovering an estimate of an information symbol by a receiver in a code division multiple access system where the information symbol is spread at a chip rate and is included within a signal that propagates through a channel with a time varying response, the method comprising the steps of:
- (A) receiving a pilot signal;
- (B) receiving a plurality of received signals each over a corresponding one of a plurality of reception elements;
- (C) generating a plurality of weights from the pilot signal based upon a cross correlation between decorrelated versions of the received signals and a desired signal that contains the information symbol;
- (D) multiplying a version of each of the received signals by a corresponding one of the weights to create a plurality of weighted estimates;
- and
- (E) adding together versions of the weighted estimates to derive an estimate of the information symbol.
A method for recovering from a signal estimates of information symbols for at least two receive paths, the signal being transmitted through a channel with a response, the method comprising the steps of:
- (A) receiving an input signal;
- (B) performing a recursive calculation to derive a matrix based on a correlation of the input signal;
- and
- (C) generating symbol estimates in response to the matrix for a plurality of signal paths.
Dependencies are inferred from the claim text.