Granted Patent B2

US 7,113,553 · App. 10/382,756 · Granted Sep 26, 2006

Abstract

Claims (30)

1. A method for mitigating the multipath interference experienced by a present CCK symbol, comprising:

(i) pre-computing a plurality of multipath interference biases which are a post-correlation representation of the intra-symbol chip interference (ICI) for the present CCK symbol;

(ii) generating correlation outputs for the present CCK symbol;

(iii) based on the plurality of multipath interference biases and the correlation outputs for the present CCK symbol, obtaining ICI-corrected correlation outputs for the present CCK symbol;

(iv) based on the ICI-corrected correlation outputs for the present CCK symbol, obtaining a set of initial candidates for the present CCK symbol;

(v) generating correlation outputs for the next CCK symbol;

(vi) based on the plurality of multipath interference biases and the correlation outputs for the next CCK symbol, obtaining ICI-corrected correlation outputs for the next CCK symbol;

(vii) based on the ICI-corrected correlation outputs for the next CCK symbol, obtaining a set of initial candidates for the next CCK symbol;

(viii) for each of the candidates for the present CCK symbol, obtaining first ISI-mitigated correlation outputs where both the ICI due to the present CCK symbol and the inter-symbol interference (ISI) due to the next CCK symbol have been corrected;

(ix) for each of the candidates for the present CCK symbol, and based on the first ISI-mitigated correlation outputs, obtaining second ISI-mitigated correlation outputs where the ISI due to the previous CCK symbol has also been corrected; and

(x) decoding the present CCK symbol based on the second ISI-mitigated correlation outputs.

2. The method of claim 1 , wherein step (viii) further includes:

for each of the candidates for the present CCK symbol, computing corresponding post-correlation ISI biases due to each of the candidates of the next CCK symbol;

for each of the candidates for the present CCK symbol, selecting from the computed post-correlation ISI biases the smallest post-correlation ISI bias; and

for each of the candidates for the present CCK symbol, subtracting the corresponding post-correlation ISI bias from its corresponding ICI-corrected correlation output to obtain the first ISI-mitigated correlation outputs.

3. The method of claim 1 , wherein step (ix) further includes:

for each of the candidates for the present CCK symbol, computing corresponding post-correlation ISI biases due to the previous CCK symbol; and

for each of the candidates for the present CCK symbol, subtracting the corresponding post-correlation ISI bias due to the previous CCK symbol from the corresponding first ISI-mitigated correlation outputs to obtain the second ISI-mitigated correlation outputs.

4. The method of claim 2 , wherein step (ix) further includes:

for each of the candidates for the present CCK symbol, computing corresponding post-correlation ISI biases due to the previous CCK symbol; and

for each of the candidates for the present CCK symbol, subtracting the corresponding post-correlation ISI bias due to the previous CCK symbol from the corresponding first ISI-mitigated correlation outputs to obtain the second ISI-mitigated correlation outputs.

5. The method of claim 1 , wherein the decoding in step (x) is accomplished by selecting, among the candidates for the present CCK symbol, the candidate whose second ISI-mitigated correlation output is the largest value, with the decoded data being the binary representation of the index of the selected CCK codeword candidate.

6. The method of claim 4 , wherein the decoding in step (x) is accomplished by selecting, among the candidates for the present CCK symbol, the candidate whose second ISI-mitigated correlation output is the largest value, with the decoded data being the binary representation of the index of the selected candidate.

7. A RAKE receiver employable in a multipath environment, the receiver receiving Complementary Code Keying (CCK) symbols that include a present CCK symbol, a previous CCK symbol, and a next CCK symbol, comprising:

channel estimation means for determining a channel impulse response based on Barker Code correlation, and generating CMF tap weights, feedback (FB) tap weights and feed-forward (FF) tap weights;

FMIC means coupled to the feedback tap weights and feed-forward tap weights for calculating a plurality of multipath interference (MPI) biases which is a post-correlation representation of intra-symbol chip interference (ICI) for the present CCK symbol;

a channel matched filter (CMF) coupled to receive the CMF tap weights from the channel estimation means and having an output;

a CCK correlator having an input coupled to the output of the channel matched filter, the CCK correlator generating correlation outputs; and

a decoder having inputs coupled to the FMIC means to receive the plurality of multipath interference (MPI) biases for mitigating the ICI from the present CCK symbol, inputs coupled to the channel estimation means for receiving the FF tap weights and the FB tap weights that are used to compute the MPI biases due to the previous CCK symbol and the next CCK symbol, and inputs coupled to the CCK correlator to receive the correlation outputs from the CCK correlator for mitigating the ICI from the present CCK symbol, and the Inter-Symbol Interference (ISI) from the next CCK symbol and the previous CCK symbol.

8. The receiver of claim 7 , further including a selector having separate outputs coupled to the channel estimation means and the channel matched filter for selecting operation in one of two separate modes.

Assignments (19)