CCK Encoding with PIC Based Microcontrollers For The RF Wireless Communications

The IEEE 802.11b is a Direct Sequence Spread Spectrum (DSSS) system very similar in concept to the CDMA Wireless, using a spread spectrum chip sequence. In the 802.11b the transmission medium is wireless and the operating frequency band is 2.4GHz. 802.11b provides 5.5 and 11 Mbps payload data rates in addition to the 1 and 2 Mbps rates provided by 802.11. To provide the higher rates, 8 ch ip Complementary Code Keying (CCK) is employed as the modulation scheme. Demodulation of the CCK modulated signal is done coherently by a RAKE receiver implementation which features a channel matched filter and Fast Walsh Transform block. This paper presents implementatio n of PIC16F84 as a CCK encoder. All low cost PIC based micro- controllers can be used, too. Here we describe the building blocks design of transmitter such as CCK encoder (digital part) and QPSK modulator (analogue part).