Ad Hoc Mode Operation
With ad hoc wireless LANs, there are no access points; therefore, the radio cards must send beacons. The ad hoc mode of operation transpires as follows:
1. After a user switches to ad hoc mode, the radio card begins sending beacons if one is not received within a specific period of time.
2. After receiving a beacon, each radio card waits a random period of time.
3. If a beacon is not heard from another station in this time, then the station sends a beacon. The random wait period causes one of the stations to send a beacon before any other station. Over time, this distributes the job of sending beacons evenly across all 802.11 stations. The sharing of the transmission of beacons among all ad hoc stations is necessary to ensure that beacons are still sent if a particular station becomes unavailable. If a station becomes disassociated with the network, then another station will send the beacon. With ad hoc networks, there is no direct connection to a wired network, which, of course, limits applications. A user, however, can configure an 802.11-equipped device as an ad hoc station, such as a PC, to provide a shared connection to a wired network. Thus, with specialized software or functions within the PC operating system, the PC can offer functions similar to those of an access point. All of the other ad hoc stations needing to reach devices on the wired network funnel their packets through the PC’s connection to the network.
1. After a user switches to ad hoc mode, the radio card begins sending beacons if one is not received within a specific period of time.
2. After receiving a beacon, each radio card waits a random period of time.
3. If a beacon is not heard from another station in this time, then the station sends a beacon. The random wait period causes one of the stations to send a beacon before any other station. Over time, this distributes the job of sending beacons evenly across all 802.11 stations. The sharing of the transmission of beacons among all ad hoc stations is necessary to ensure that beacons are still sent if a particular station becomes unavailable. If a station becomes disassociated with the network, then another station will send the beacon. With ad hoc networks, there is no direct connection to a wired network, which, of course, limits applications. A user, however, can configure an 802.11-equipped device as an ad hoc station, such as a PC, to provide a shared connection to a wired network. Thus, with specialized software or functions within the PC operating system, the PC can offer functions similar to those of an access point. All of the other ad hoc stations needing to reach devices on the wired network funnel their packets through the PC’s connection to the network.
