Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
1
2
3
4
g ( x)
= ( x −α
)( x −α
)( x −α
)( x −α
)
Equation 9
The RS binary symbol representation for delimiters of α 0 is 0b0001, where the left most bit of this RS symbol is
the most significant bit (MSB). This way, the binary representation of each of the redundancy symbols
generated on the Galois field GF(2 4 ) denoted as p3, p2, p1, p0 will be represented as RSX15, RSX14, RSX13, and
RSX12 for the symbol p3, RSX11, RSX10, RSX9, and RSX8 for the symbol p2, RSX7, RSX6, RSX5, and RSX4 for the
symbol p1 and RSX3, RSX2, RSX1, and RSX0 for the symbol p0, where X denotes the RS codeword number.
The following figure shows the final binary level representation of the delimiter:
I 175 I 174 I 144 RS1 15 RS1 0
I143 I142 I112 RS215 RS20 I 15
I 14
CRC 0 RS6 15 RS6 0
Figure 7 Reed Solomon bit format
The first bit to be transmitted is the leftmost of the first codeword (I175), followed by the rest of the bits of the
RS codeword. Then, the second codeword, and so on. This is illustrated in
175
174
3.3.1.3 Delimiter Interleaving
I
I
... RS1
I ... RS2
I ....... RS5
I ... RS6
0
143
Submission page 41 UPA-OPERA
0
111
Figure 8 Reed Solomon bit order
After RS encoding, the six resulting RS codewords shall be interleaved with interleaving depth of six RS
codewords and 4 bits granularity, in such a way that the first four bits of each RS codeword shall be sent first to
the interleaver, then, the second 4 bits of each of the six RS codewords and so on. We can group the bits in
nibbles for clarity:
0
15
0