User guide

45 Mbps Backhaul User Guide
Issue 3, December 2004 Page 16 of 113
3 General Considerations
3.1 Frequency Planning
The 45 Mbps Backhaul operates over the frequency range 5.725 to 5.850 GHz (defined as the USA ISM band
and the ETSI 5 GHz C band), utilizing a 11 MHz wide channel. Setting of the operating frequency channel is
automatic and is carried out by the built in Dynamic Frequency Selection (DFS) functionality.
The user can configure the 45 Mbps Backhaul to avoid using certain frequencies to prevent interference to other
users of the band and prevent operation in parts of the band containing interference. The use of this functionality
is described in detail in section 6.3.5 “Spectrum Management”.
3.2 Distance
The 45 Mbps Backhaul will operate at ranges from 100 m to 200 km, this within 4 modes 0-5km, 0-40km,
0-100km, and 0-200km. Operation of the system will depend on obstacles in the path between the units.
Operation at 40 km or above will require a near Line-of-Sight path. Operation at 100m could be achieved with
one unit totally obscured from the other unit, but with the penalty of transmitting at higher power in a
non-optimal direction, thereby increasing interference in the band. This subject is covered in more detail in
section 4.1.3 “Path Loss Considerations”.
3.3 Networking Information
The 45 Mbps Backhaul operates as a transparent Ethernet bridge. Each unit requires an IP address. This IP
address is for management purposes only and it plays no part in the operation of the system. IP addresses are
assigned during initial configuration as described in section 5.2 “Installation Procedure”.
3.4 Lightning Protection
The amount of lightning protection is dependent on regulatory requirements and the end user requirements. The
standard 45 Mbps Backhaul ODU is fitted with surge limiting circuits and other features to minimize the risk of
damage due to nearby lightning strikes. These standard features may require some additional equipment to be
configured as part of the system installation to be fully effective. Motorola recommends the use of shielded
cable and surge arrestor to protect connected equipment from nearby strikes.
Note: The 45 Mbps Backhaul is not designed to survive direct lightning strikes. For this reason the unit should
not be installed as the highest point in a localized area, unless specific precautions are taken. See section 9
“Lightning Protection”.
3.5 Electrical Requirements
The 45 Mbps Backhaul is supplied with a variable input voltage (90-264V, 47-63Hz AC) inline power supply
unit which is incorporated into the Power Indoor Unit (PIDU). The 45 Mbps Backhaul requires one mains AC
power outlet at each end of the link.