Decoding method and device

1. A method of decodinq a symbol sequence in a received DS-CDMA signal, comprising the steps of:

iterative calculation of a hard-decision vector, using a decision threshold having a value based on the probability of each ternary alphabet element of each symbol in the hard-decision vector;

demodulating the received signal, thereby providing a symbol sequence;

calculating a matrix product of the symbol sequence and a Hadamard decoding matrix;

calculating an estimate of a decision threshold, assuming equal probability of the ternary alphabet element of each symbol in the symbol sequence;

calculating a hard-decision vector using the calculated decision threshold;

calculating an estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector;

calculating a decision threshold using the estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector; and

iterating the steps of calculating a hard-decision vector, calculating an estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector and calculating a decision threshold using the estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector, until the calculation of a decision threshold converges or the number of iterations reaches a predetermined maximum number of iterations.

2. The method according to claim 1 , wherein the symbol sequence is a sequence of acquisition indicators in an acquisition indicator channel and further comprises the step of:

selecting the AI of interest from the calculated hard-decision vector using a predetermined index.

3. A user equipment apparatus capable of decoding a symbol sequence in a received DS-CDMA signal, comprising:

means for iterative calculation of a hard-decision vector, using a decision threshold having a value based on the probability of each ternary alphabet element of each symbol in the hard-decision vector;

means for demodulating the received signal, thereby providing a symbol sequence;

means for calculating a matrix product of the symbol sequence and a Hadamard decoding matrix;

means for calculating an estimate of a decision threshold, assuming equal probability of the ternary alphabet element of each symbol in the symbol sequence;

means for calculating a hard-decision vector using the calculated decision threshold;

means for calculating an estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector;

means for calculating a decision threshold using the estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector; and

means for iterating the steps of calculating a hard-decision vector, calculating an estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector and calculating a decision threshold using the estimate of the probability of each ternary alphabet element of each symbol in the hard-decision vector, until the calculation of a decision threshold converges or the number of iterations reaches a predetermined maximum number of iterations.

4. The apparatus of claim 3 , wherein the symbol sequence is a sequence of acquisition indicators in an acquisition indicator channel and further comprises means for selecting the AI of interest from the calculated hard decision vector using a predetermined index.

5. An apparatus, comprising:

a RF transceiver;

an inner receiver coupled to the RF transceiver;

a channel decoder coupled to the inner receiver;

a controller coupled to the RF transceiver, the inner receiver and the channel decoder; and

a memory coupled to the controller, wherein the apparatus is capable of selecting acquisition indicators comprising calculating a decision threshold using an estimate of a probability of each ternary alphabet element of each symbol in a hard-decision vector, until a calculation of a decision threshold converges or a number of iterations reaches a predetermined maximum number of iterations.

6. The apparatus of claim 5 , wherein the inner receiver comprises a channel equalizer.

7. The apparatus of claim 5 , further comprising at least one of a speaker, microphone, keyboard, and display coupled to the controller.

8. The apparatus of claim 5 , wherein the inner receiver comprises a channel equalizer.

9. A method of decoding a symbol sequence in a received DS-CDMA signal with a user equipment, comprising the steps of:

demodulating a received signal;

computing a matrix product of the demodulated signal and a Hadamard decoding matrix;

estimating a decision threshold;

calculating a hard-decision vector with the computed matrix product;

estimating probability of each ternary alphabet element of each symbol in the hard-decision vector;

calculating a new decision threshold using the estimate of the estimating probability step; and

iterating until a calculation of a decision threshold converges or the number of iterations reaches a predetermined maximum number of iterations to select hard-decision vector elements.