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Radio signal interference in WLAN systems can go two ways: The WLAN can cause interference to other devices operating in or near it´s frequency band. Or conversly, other devices can interfere with WLAN operation, provided their signal is stronger. The result is a scrambled signal, which of course prevents the nodes from exchanging information between each other or access points. WLANs using infrared technology generally experience line-of-sight problems. An object blocking this line between the two WLAN units is very likely to interrupt the transmission of data.
TCP/IP provides reliable connection over wired LANs, but in WLAN it is susceptible to losing connections, especially when the terminal is operating within the marginal WLAN coverage. Another connection related issue is IP addressing. The wireless terminals can roam between access points in the same IP subnet but connections are lost if the terminal moves from one IP subnet to another.
This is an important aspect in WLAN. It is difficult to restrict access to a WLAN physically, because radio signals can propagate outside the intended coverage of a spesific WLAN, for example an office building. Some security measures against the problem are using encryption, access control lists on the access points and network identifier codes. The technical operation of WLANs also works against the intruder: Frequency hopping and direct sequence operation makes eavesdropping impossible for everyone else than the most sophisticated.
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