NEC IPASOLINK 400 Installation And Provisioning page 44

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Reference modulation: This selection determines the maximum available power. In order to get maximum
power at QPSK, select Reference Modulation = QPSK. Element setting.
Note. The transmitter power depends on a) MTPC setting and b) current modulation. When the reference
modulation is QPSK, the MTPC setting allows selecting the maximum power. But even with MTPC selected,
the power is automatically adjusted slightly lower according to the current modulation automatically
selected by AMR.
In other words, MTPC includes an automatic TX power fine adjustment part.
EXAMPLE
License allows -6dBW or +24dBm. If the reference modulation is selected as 256QAM and adaptive
modulation is used, the maximum MTPC setting is +19 dBm. When the hop fades, the modulation is
changed all the way down to QPSK, but nevertheless the power is limited to +19 dBm.
If QSPK is selected as the reference, the maximum MTPC setting is +24 dBm. The hop will then tolerate 5 dB
more fading at QPSK (will use +24 dBm), but will normally (no fading) use 256QAM at +19 dBm.
Radio Mode – Select High Capacity, unless otherwise instructed. This setting selects the error correction
code settings. High System Gain will give about 1 dB more fade margin, but will reduce the capacity by
several Mbit/s (shown in ETH Bandwidth). This setting has to be the same at both ends of the hop. Hop
setting.
E1 and STM-1 Mapping (CH) – Capacity reserved for E1- and STM-1 -channels. Change under AMR / Radio
Mapping Configuration. Hop setting.
ETH Bandwidth (Mbps) – Indicates the remaining available Ethernet capacity (Mbit/s) for the reference
modulation. Radio Mode and E1/STM-1 mapping setting will change this value.
TX and RX Frequency (MHz) – Set the frequencies given in the license exactly. Element setting.
If the setting fails, check that the ODU sub band is correct and that the HIGH/LOW version is correct. Check
the ODU information or Inventory. Verify that the correct modem is selected for configuration.
Note. Setting of the frequency is not possible without a proper ODU connected to the modem.
Frame ID – default 1.
Frame ID has to be identical for both modems at each end of the radio connection. Frame ID is checked in
order to prevent communication with a wrong modem in case the remote transmitter fails or fades away.
Using different Frame ID settings may be necessary in a hub with several iPasolink ODUs using the same
channel. XPIC modems using the same channel must have different ID values. Default = 1.
TX Power Control – Select MTPC (fixed power excluding AMR adjustment), unless otherwise instructed.
Default setting = MTPC.
Automatic ATPC mode might be necessary for the remote sites connected to a hub, in order to prevent
excessive interference from other hops re-using the same or adjacent channel.