4.4 Conclusion

In this chapter, we focused on the problem of blind detection of CDMA signals that are modulated with long spreading codes. We first discussed the problem in the context of 2D RAKE receivers. The situation arises in uplink CDMA where the base station employs an array of antennas. A class of 2D RAKE reception schemes have been presented. Although the same approaches can be used in downlink, a more appealing strategy is to equalize the "common" channel and restore the orthogonality before extracting the desired signal via despreading.