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

4-June-07 P1901_PRO_016_r0
s
SOT
( n)
=
Submission page 63 UPA-OPERA
5
∑
i=
0
s
D,
i
Equation 29
( n − 256i)
Therefore the maximum duration of the SOT (if the maximum window size is used) will be 40 μs.
3.8.4 Channel estimation symbols
The channel estimation symbols are used to estimate the channel quality at the receiver side. After the channel
estimation the receiver may send a new bit-loading table to the transmitter (see 9.1.2). These symbols shall be
known by the transmitter and the receiver to allow a correct estimation under all conditions. Therefore, a
pseudorandom sequence generator shall be used as the modulator input instead of the output from the 4D-TCM
encoder.
The pseudorandom sequence generator shall be the 11-bit PN generator with characteristic polynomial given by
Equation 30.
( x)
f = +
2 11
1+ x x
Equation 30
This symbol shall be modulated using 2 bits per subcarrier. Therefore, two 11-bit PN generators with different
seeds shall be used. Figure 19 explains how the Δ bk
value is formed. The SYMBOL NUMBER value is 1 for
the channel reference symbol, and is incremented by 1 for every symbol there after.