Technical information

Chapter 2: AT+i Commands Reference
May 31, 2008 AT+i Commands Reference Manual 2-55
Ad-Hoc Networks
An ad-hoc network is a Wireless Local Area Network (WLAN) in which some of the stations are
part of the network only for the duration of a communications session or, in the case of mobile or
portable devices, while in some close proximity to the rest of the network.
Ad-hoc networks do not require an Access Point (AP) to enable communication among stations.
Each station can create a new ad-hoc network or join an existing one. Networks can freely merge
into a single network or split into smaller ones, thus adapting to changing conditions such as
topology, signal strength, and proximity to nearby ad-hoc networks. Combined with a W24
configured as an iRouter, an ad-hoc network can connect to the Internet through a dial-up or
GPRS modem.
Configuration
Configuring the W24 to operate as a station in an ad-hoc network requires setting the following
parameters:
• WLSI must be set to either '!' or '!<SSID>'. When it is set to '!', W24 continuously searches
for existing ad-hoc networks in its vicinity and joins the one having the strongest signal.
When it is set to '!<SSID>', W24 searches for an ad-hoc network having the specified
Service Set IDentifier (SSID). If it finds one it joins it, otherwise it creates a new network
with this SSID.
• WLCH must be set to a default value. This value indicates the communication channel (1-13)
to be used for beacon transmission in the ad-hoc network. When W24 joins an already
existing network, it adopts the channel used by that network. If WLSI=!<SSID> and
WLCH=0, W24 will only join an already existing network.
W24 Behavior in Ad-Hoc Mode
Automatic Scanning for Existing Ad-Hoc Networks
After power-up, W24 automatically attempts to locate and connect to an ad-hoc network, unless
the WLSI parameter (SSID) is set to (*).
If the WLSI parameter contains an SSID string preceded by (!) or set to (!), W24 scans for ad-hoc
networks only.
Creating a New Ad-Hoc Network
If W24 does not detect any ad-hoc networks in its vicinity, and the WLSI parameter contains an
SSID, W24 creates a new ad-hoc network with its own BSSID.
Joining an Existing Ad-Hoc Network
If W24 detects ad-hoc networks in its vicinity and the WLSI parameter is set to (!), W24 joins the
network having the strongest signal. Otherwise, W24 joins the network whose SSID is set by the
WLSI parameter.