Patent ID: 7480493

Claim:
A method in a communication device for estimating spreading codes for other destination devices which are present in a signal that has been transmitted using code division multiple access techniques, and wherein the communication device has knowledge only of its own spreading code, comprising: a. receiving said signal at said communication device and generating samples thereof; b. computing a weight vector using auto-regression techniques based on samples of the received signal over time, and computing a power spectral density from the weight vector as a function of the full spreading code matrix to determine correlations among spreading codes used for bits present in the received signal, wherein computing the weight vector comprises computing a M+1 =∥ε∥ 2 (R M+1 ) −1 u M+1 , where R M+1 is a correlation matrix Y M+1 (Y M+1 ) H , Y M+1 is a matrix representing the received signal at time M+1, u M+1 is a unit vector and ∥ε∥ 2 is a mean-square prediction error; and c. identifying from a peak in the power spectral density a spreading code associated with bits present in the received signal for another destination device.