Joint equalization and decoding for complementary code keying (CCK) modulation

The 5.5 and 11 Mbps modes of the 802.11b wireless local area network (WLAN) standard use a type of modulation known as complementary code keying (CCK). This is a kind of block coded modulation that codes information bits into blocks of 8 QPSK symbols and was originally chosen to deal with small multipath delay spreads on the order of 10-50 ns with Rake receivers. However, 802.11b systems are now being used in home, office and warehouse environments where the multipath delay spread can be much greater - on the order of 200 ns. Such environments require the use of equalizers for acceptable performance. In this paper we present algorithms and implementations for joint equalization and CCK decoding that improve the performance of the system substantially over separate equalization and decoding.