Oki Techno Centre (Singapore) Pte Ltd

Tingwu Wang

Hiroki Sugimoto

Ping Xie

Kai Ren Tan

A technique is proposed for normalizing the multi-bit output of a RAKE receiver by automatically selecting from it fewer bits which are representative of the data in the CDMA signal. The invention is applicable to a CDMA signal in which the data is transmitted discontinuously and a pilot symbol is inserted into the data sequence and transmitted at a different power level. The proposed technique may be operated either on the basis that the power ratio of the pilot part of the CDMA signal to the data part is known, or alternatively without any knowledge of this power ratio. In both cases the pilot part is used to determine the bit position on which the normalization works, and also the fine adjustment of the data part of the CDMA signal.

Method and apparatus for normalizing CDMA RAKE output

Adders each add up an addition value sent from a metric calculator and a state metric read from a memory. A maximum value selector generates a first likelihood when a data bit is 1, based on the addition values added up by the adders. A maximum value selector generates a second likelihood when a data bit is 0, based on the addition values added up by the adders. A subtracter subtracts the second likelihood from the first likelihood to generate a likelihood ratio, and a subtracter subtracts data from the likelihood ratio and generates extrinsic information. A re-normalizer multiplies the extrinsic information by a predetermined value to re-normalize it and temporarily stores it in a memory. The extrinsic information stored in the memory is used as the prior probability information for the next iterative decoding.

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Singapore, Singapore

Tingwu Wang