Roaming is the ability of a portable computer user to communicate continuously while moving freely throughout an area greater than that covered by a single access point. Before using the roaming function, the workstation must make sure that it is the same channel number with the Access Point of dedicated coverage area.
To achieve true seamless connectivity, the wireless LAN must incorporate a number of different functions. Each node and accesspoint, for example, must always acknowledge receipt of each message. Each node must maintain contact with the wireless network even when not actually transmitting data.
Achieving these functions simultaneously requires a dynamic RF networking technology that links access points and nodes. In such a system, the user's end node undertakes a search for the best possible access to the system. First, it evaluates such factors assignal strength and quality, as well as the message load currently being carried by each access point and the distance of each accesspoint the wired backbone. Based on that information the node next selects the right access point and registers its address.
Communications between end node and host computer can then be transmitted up and down the backbone. As the user moves on, the endnodes RF transmitter regularly checks the system to determine whether it is in touch with the original access point or whether it should seek a new one. When a node no longer receives acknowledgment from its original access point, it undertakes a new search. Upon finding a new access point, it then reregisters, and the communication process continues.
For best results, setup your access points on different channels, but use the same SSID. If you are using WEP, then enter the same key on all the access points.