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

4-June-07 P1901_PRO_016_r0
The transmitter must provide means to modify the transmission power of each subcarrier with a granularity of at
least 6 dB. Once the transmitter introduces the notches in the transmitted signal, other mechanisms like the
ABLP (see 9.1.2) will automatically adapt accordingly.
3.13.2 Modulation error vector magnitude
Modulation errors may be caused by quantization in the digital processing and by linear and non-linear
distortion in the analogue processing of a BPL transmitter.
The normalized mean modulation error vector magnitude is defined as the RMS value of the modulation error
vector magnitude divided by the RMS value of the modulation vector.
• N denotes the number of subcarriers.
•
•
S(
k)
denotes the measured complex symbol of the k-th subcarrier.
S0 ( k)
denotes the ideal complex symbol of the k-th subcarrier.
The RMS error vector magnitude may be expressed as:
EVM
=
1
N
∑
k=
1
( k)
− S ( k)
Submission page 67 UPA-OPERA
N
1
N
S
N
∑
k=
1
S
0
0
( k)
Equation 32
and can be measured with a multi-tone error vector magnitude meter.
The EVM shall not exceed 1%
3.13.3 Power Control
2
2
⋅100%
This specification allows for the optional implementation of a Power Control mechanism, using the BPS and Rx
Att information supplied in the ABLP packet (9.1.2.4) and the Power Control bits in the Token Announce (See
4.4.1). The target of the power control is to transmit the lowest power that attains a given performance.
Therefore a node may adjust its transmission power until the desired value of BPS is reached. The process is
depicted in Figure 20.