A RAKE receiver with ICI/ISI equalizer for CCK wireless LAN modem

Abstract

In this thesis, we propose a RAKE receiver for complementary code keying (CCK) codes, which is suitable for the multipath environment with large delay spread. The RAKE receiver principle is good for modest multipath of around 100ns delay spread because the RAKE receiver coherently combines multipath components with a separate correlation receiver for each of the multipath components to provide SNR enhancement. However, as the delay spread is larger and the data rate of systems goes higher up, inter-symbol interference (ISI) and inter-chip interference (ICI) generated due to multipath environments are increased. This is the case for wireless LANs. To handle the increasing ISI and ICI, CCK wireless LAN modem needs ISI and ICI cancellation technique, together with RAKE processing. So our proposed system is based on channel matched filter (CMF) with decision feedback equalizer (DFE) and contains codeword DFE structure. CMF is applied for RAKE processing and DFE and codeword DFE is used for ISI and ICI cancellation. In our system, ICI and ISI are calculated by using detected CCK codeword. Also it uses the error correcting capability of CCK codes, and it can remove ISI and ICI at the same time.