ai) i = 1...8. 8-bit complex words. For the 11 Mbps data rate, 256 out of these possibilities are actually used-which one being Figure 5.2-13 is a summary of the development of determined by the sequence of 8 data bits applied to code words a for 11 Mbps rate CCK modulation. High a particular symbol. Only 16-chip sequences are needed rate modulation is applied only to the payload -MPDU for the 5.5 Mbps rate, determined by four data bits per in Figure 5.2-11. The code word described in Figure symbol. The high-rate algorithm describes the manner in 5.2-13 is used as shown for the first symbol and then which the 256 code words, or 16 code words, are chosen every other symbol of the payload. However, it is SERIAL 11 MBPS ROTATOR CODE WORD ENCODER QUADRATURE MODULATED MULTIPLEXER MODULATOR CARRIER LOCAL 11 MHZ CLOCK OSCILLATOR 1.375 MHZ CHIP CLOCK CHIP CLOCK Figure 5.2-12 High-rate modulator-11 Mbps. CHAPTER 5.2 Short-range wireless applications and technologies Data symbol: do di d2 d3 d4 ds d6 d7 Table 5.2-1 5. 5 mbps CCK decoding. Phase Table d3,d2 di di+1 Phase (do,d1) = Q1 Phase (d2,d3) = Q2 Phase (d4,d5) = Q3 Phase (d6,d7) = Q4 16 complex chip sequences. Four 8-element code words li=cos(ai) (complex chip sequences) are determined using the last Qi=sin(a) two data bits of the symbol, d2 and d3. The arguments 03=01+42+ 04=01+44+1809 =1...8 (angles) of these code words are shown in Table 5.2-1. Bits do and dj are used to rotate the code words relative as=01+42+93 to the preceding code word as in 11 Mbps modulation 06=01+03 and shown in the phase table of Figure 5.2-13. Code words are modified by 180° every other symbol, as in as=Q1 11 Mbps modulation. Figure 5.2-13 Derivation of code word. The concept of CCK decoding for receiving high rate data is shown in Figure 5.2-14. For the 11 Mbps data rate, a correlation bank decides which of the 64 possible codes modified by adding 180° to each element of the code best fits each received 8-bit symbol. It also finds the ro- word of the second symbol, fourth symbol, and SO o