Nortel Networks DCT1900 - Manual (Page 121)

Technical Product Manual - DCT1900
Configuration Directions, Base Station Powering
Config-DCT1900/R8/mw 4-1
© 2000-2005
C HAPTER 4
Base Station Powering
4.1 General
After a Base Station plan has been made (see Chapter 3), it must be established which powering
method is more suitable to power the Base Stations. The methods for powering a Base Station are:
z Via the RE
z By a remote power supply
The choice of the method depends upon:
z The distance between the RE and the Base Stations
z The total number of Base Stations
z Whether power back–up is needed or not
z Installation costs
Paragraph 4.2 describes the powering of Base Stations by means of a remote power supply.
Paragraph 4.3 describes the powering options for the Modular Cabinet. The tables used in this
chapter are given in Paragraph 4.4.
The length limits for the Base Station cable are described below.
Data Limited Length of the Base Station Cable
Data transmission via twisted pairs is limited to a certain range. The "data limited" length of the
cables between the RE and the Base Stations depends on the system board used (CLU or SLU),
the characteristics of the cable, and the noise on the cable. Table 4–1 shows the data limited
length for some cables.
Note:
Since it is not possible to predict the noise level in an environment and its influence on a cable, the
values from the table should be taken as a guide-line more than a rule. Practically, the maximum
length may exceed these values, in case there is less noise and vice versa if there is more noise.
Power Limited Length of Base Station Cable
When a Base Station is powered via the cabinet, the maximum length between the Base Station
and the RE depends on the supply voltage, the number of twisted pairs used and the wire size.
The length of the cable should never exceed the "data–limited" length of the cable.
4.2 Powering Base Stations by a Remote Power Supply
When Base Stations are powered by a remote power supply, only a cable with two twisted pairs is
required between a Base Station and the RE for data transfer (see Figure 4–1).
Powering Base Stations with a remote power supply can be done by using the EPP pins on the
Base Station connector. Base Stations can be powered individually or in clusters from a central
power source. A cluster can be e.g. Base Stations on the same floor or in the same building,
assuming that Base Stations within the cluster are close enough to the remote power supply. The
length of the cable between the Base Station and the RE is "data limited". See Table 4-1 for the
maximum cable length.