CB-OWSPA311GI-01 ConnectBlue, CB-OWSPA311GI-01 Datasheet - Page 16

• Manufacturer Part Number: CB-OWSPA311GI-01
• Description: KIT START OEM WIRELESS LAN RS232
• Manufacturer: ConnectBlue
• Series: OEM Serial Port Adapter™r
• Type: Bluetoothr

Specifications of CB-OWSPA311GI-01

• Frequency: 2.4GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 809-1018

Improving Roaming in Infrastructure Networks
CPU Idle, Improving Response Times and Throughput
5.5 Pin Diagrams
This introduces a roaming issue. If the module that left the network returns (returns into range),
it will still believe it is the access point of the network. Suddenly we have two modules acting as
access point. These modules effectively operate on different networks and will not be able to
communicate.
To try to remedy this issue connectBlue has introduced a trigger setting into its OWSPA311g
module. This trigger will activate if one module has been alone in a network for too long. It will
then try to scan for present network and connect to it if possible. This timeout period is adjust-
able via an S register.
However, this only solves the most basic of roaming cases for ad-hoc. Imagine an ad-hoc net-
work with four modules. If two modules leave at the same time and leaves the two other mod-
ules behind. There is little chance of the four modules reconnecting again without interaction.
Therefore, if roaming if desired, please look into planning a proper network with access points
spread out over the desired area.
If you are using the module in an infrastructure network there is one way to improve roaming
times radically. By using the command AT*AGCL you can define the channel list the module
should use. By default, this channel list includes all legal channels but since it is unlikely that one
network is using all channels available you can narrow it down. This means that instead of
scanning 11 to 14 channels you can set it to scan only the ones in your network, which should
be very few.
So, for instance, if your network only uses 3 channels, say 1, 6 and 11. When a connection is to
be established the module will only scan the three channels instead of 11 or 14, which takes a
lot shorter time. When a module later moves out of the range of one AP, it will only have to
scan these three channels again to find an appropriate access point.
By default, the modules cpu is put into a mode where it will try to sleep as often as possible,
thus conserving power. Setting the Power Save mode to Online does not affect this specific set-
ting. To adjust this you need to use the S-register 4005.
At low speeds, the cpu idle setting will not make a difference in response times or throughput.
However, at higher uart speeds, from 230 Kbit/s and up throughput will be affected. If you de-
sire maximum throughput at these speeds, you should look into changing this setting.
These diagrams show the pin behaviour for different configurations.
Figure 1 Default configuration, DTR mode = at startup
Version 1.6.6 - 2009-11
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