A projection-based semi-blind channel estimation for long-code WCDMA

The third generation (3G) wireless systems such as Wideband CDMA(WCDMA) employ coherent detection where pilot symbols for channel estimation are transmitted simultaneously with data using orthogonal channelization codes. The orthogonality of codes, unfortunately, is lost easily due to multipath delays. Furthermore, the use of long scrambling code introduces time variation in channel model. In this paper, based on the projection of time-varying subspaces, we present a semi-blind channel estimation technique for long code CDMA systems that use code division multiplexed pilot symbols.

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