PRELIMINARY
CYW43340
Figure 25. WLAN PHY Block Diagram
CCK/DSSS Demodulate
Filters and Radio
Comp
Frequency and
Timing Synch
Descramble and
Deframe
OFDM Demodulate
Viterbi Decoder
Carrier Sense, AGC, and
Rx FSM
Buffers
MAC
Radio Control Block
FFT/IFFT
Interface
AFE and
Radio
Tx FSM
Modulation and
Coding
Common Logic Block
Frame and
Scramble
Filters and Radio Comp
PA Comp
Modulate/Spread
COEX
One of the key features of the PHY is its space-time block coding (STBC) capability. The STBC scheme can obtain diversity gains in
a fading channel environment. On a connection with an access point that uses multiple transmit antennas and supports STBC, the
CYW43340 can process two space-time streams to improve receiver performance. Figure 26 is a block diagram showing the STBC
implementation in the receive path.
Figure 26. STBC Implementation in the Receive Path
Descramble and
Deframe
Equalizer
Demod Combine
Demapper
Viterbi
FFT of 2 Symbols
hold
Transmitter
hnew
Weighted
Averaging
Channel h
hupd
Symbol
Memory
Estimate
Channel
In STBC mode, symbols are processed in pairs. Equalized output symbols are linearly combined and decoded. The channel estimate is
refined on every pair of symbols using the received symbols and reconstructed symbols.
Document Number: 002-14943 Rev. *L
Page 43 of 96
CYPRESS [ CYPRESS ]
