User's Manual

4 Antenna and Frequency Planning
This Section describes some of the issues involved in planning a wireless network deployment.
The ARCell wireless system uses different frequencies for Downstream (Hub to subscriber) and
Upstream (subscriber to Hub) communications, which is referred to as a Frequency Division
Duplex system.
The Downstream uses a channel within the UNII “high” band, 5.725-5.825 GHz. Upstream uses
a channel within the UNII “low” band, 5.250-5.350 GHz.
4.1 Antenna Patterns
Each Hub Transceiver has a specific antenna built in. They are labeled according to their
horizontal pattern:
• Omnidirectional (360 degrees)
• 90-degrees directional
• 60-degree directional
Each antenna is directional in the vertical plane as well, with the strongest power straight out
from the antenna’s axis. This means that elevations above straight out from the front of the
antenna (up in the sky) receive less power, as do elevations below straight out. Therefore, the
antenna is normally pointed at the furthest subscriber to be served, with the lower elevations
providing appropriately less power to closer subscribers. This pointing is usually referred to as
“downtilt” because the typical directional transceiver is pointed downward by less than 1 degree.
Omnidirectional antennas need to be mounted vertically, i.e., no mechanical downtilt. The
ARCell omni antenna has an electrical downtilt of about 1 degree.
4.2 Frequency Planning – Downstream
4.2.1 Available Channels
There are 16 available downstream channels in the ARCell standard 5.725-5.825 GHz UNII
band. The frequencies (Table 4-1) were chosen such that the resulting signal as received by
the wireless cable modem (WCM) corresponds to a standard EIA CATV channel.
June 2003 Page 4-1