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Cooper Bussmann 945U-E Wireless Ethernet Modem & Device Server User Manual
Rev Version 2.14
Channel Width
The channel width setting will apply only when there are no entries in the scan list.
This allows you to select channel width bands for the background scan. If 5 MHz is
selected, only 5-MHz channels will be scanned during the background scan. Default
is Auto, which means all channels will be scanned.
Save Changes
Saves changes to non-volatile memory. Changes will not take effect until module is
reset.
Save Changes and
Reset
Saves changes to non-volatile memory and reset module.
When fast roaming is enabled, the client goes off-channel and periodically performs a background scan to identify
available access points. When access points are identified, the RSSI is recorded as a potential connection. It takes
50 msec to scan each channel, with a 1-second delay between each scanned channel. Scanning 10 channels will
take 10 seconds, during which time latency of up to 50 msec will occur and any throughput traffic is essentially
paused and buffered for retransmission when complete. It is therefore recommended the scan list be used to limit
the number of channels the client needs to scan, thus reducing the overall scan time.
During the background scan a client will scan all of the channels in the scan list to identify better access points. If
no channels are configured, it will scan all channels.
Figure 44 Scan List
The configuration in Figure 44 shows that the client will start scanning when the RSSI of its current connection to
the access point falls below -90 dBm. When this happens it will scan the list of access points configured in the
roaming scan list (in this case, channels 6, 15, 16 and 26), and if any of the RSSI levels are greater than -84 dBm,
it will change to this access point, i.e. 6 dB (Roam Changeover Threshold) better than -90 dBm (Roam Scan
Threshold).
3.16 Repeaters (WDS)
The range of a wireless network can be extended by allowing access points to behave as repeaters and forward
traffic to other access points. Access point to access point communications is also known as wireless distribution
system (WDS). The 945U-E offers very powerful WDS configuration, allowing for a mesh network with self-healing
functionality. Alternatively, fixed access point to access point links can be configured for optimized throughput.
Each 945U-E access point supports up to 10 separate interfaces for WDS links to other devices. Each WDS
interface can be either a bridge or router interface. Refer to “1.0 Network Topology” for more information on bridge
versus router. If you need a simple repeater network (Figure 45), use a bridge interface.
