User guide

45 Mbps Backhaul User Guide
Issue 3, December 2004 Page 46 of 113
6.3.3.3 Wireless Configuration
Step 2 of the installation wizard requires the installer to enter the wireless configuration parameters.
Figure 18 Installation Wizard Wireless Configuration
Target MAC Address The MAC Address of the peer unit that will be at the other end of the wireless link. This
is used by the system to ensure the unit establishes a wireless link to the correct peer.
The MAC Address can be found embedded within the serial number of the unit. The last six characters of the
serial number are the last three bytes of the unit’s MAC address.
(Note: The 45 Mbps Backhaul system is shipped as a pair of units with pre-loaded correct MAC addresses.
MAC addresses will only need to be entered if an existing unit has to be replaced in the field or the units
configuration has been erased).
Master Slave Mode At this point it is necessary to decide which end will designated a Master. The Master unit
is the controlling unit with respect to the Point-to-Point link and its maintenance. The master transmits until the
link is made, while the Slave listens for its peer and only transmits when the peer has been identified.
Link Symmetry By default Link Symmetry of a Point-to-Point link is ‘Symmetrical Data Rate (1:1)’ in this
configuration the ratio of time the wireless link spends transmitting and receiving is equal. When Link
Symmetry is configured to Asymmetric Data Rate (2:1) the wireless link Master will spend twice as long
transmitting as receiving. It should be noted that the data rate available to the end users might not follow these
ratios exactly. The exact data rates will be dependant on the prevailing modulation. If the direction you want to
install the link asymmetry not achievable in the current configuration then the master and slave modes of both
45 Mbps Backhaul units will need to be reversed.
ARQ State Automatic Repeat reQuest (ARQ) is a mechanism where packets lost due to transmission errors over
the wireless link are retransmitted rapidly. The retransmission helps to prevent TCP congestion mechanisms
from inadvertently interpreting intermittent pack loss as network congestion. ARQ must be enabled on both
ends of the Point-to-Point link for it to function.