| 摘要 |
An apparatus comprises a detection processor (203) for detecting retransmission feedback messages in response to a detection threshold. A threshold processor (207) determines the detection threshold in response to a noise estimate generated by a noise processor (209). The noise processor comprises a sub-symbol generator (211) which divides a retransmission feedback symbol into a plurality of sub-symbols. Each of the sub-symbols is despread by a spreading code with a lower spreading factor than a spreading factor of the retransmission feedback symbol. A difference generator (213) then generates difference symbol values between the plurality of sub-symbols and a noise estimator (215) generates the noise estimate in response to the difference symbol values, for example by determining the variance of the difference symbol values. An improved noise estimate may be determined resulting in improved detection performance and thus improved retransmission performance.
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