![]() The first is frequency, the actual location-measured in hertz-within the radio spectrum where the signal exists. To understand spectrum analysis, you must first learn a few fundamental metrics used to describe any RF signal. But they will likely be less forgiving as wireless networks become the primary access medium and their connections get disrupted by interference. With the current overlay nature of wireless networks, users can overlook many of the physical layer problems: If they can't connect to the wireless network, they just plug into the wired network. If a stream of VoIP packets is corrupted midtransmission, it can leave the caller with dead silence. With more demanding services like VoIP and video, interference problems become more noticeable because these real-time applications depend on a steady stream of data. ![]() 802.11 corrects for interference and packet corruption by retransmitting data, so any problems are relatively invisible to low-throughput and bursty applications like Web surfing. (See " Running Interference", and for more on the common sources of interference, see " How to Block WLAN Interference" ).Īlthough many wireless networks operate sufficiently well for Web and e-mail applications, emerging high-throughput and real-time applications such as VoIP (voice over IP) on your 802.11 WLAN will magnify existing interference. Just how these obstacles affect the WLAN varies from minor throughput degradation to, in the worst case, complete disconnection from the wireless network. ![]() Unlike Ethernet, where transmission takes place over a guarded and closed medium, wireless communications cross a vulnerable no-man's land where there are no guarantees: IEEE 802.11 networks operate in the same unlicensed spectrum as Bluetooth headsets, cordless phones and microwave ovens, and transmissions must contend with a slew of interference sources and physical obstructions before they reach their final destination. ![]() Although the protocols and applications flowing over wireless and Ethernet are typically identical, the underlying physical layer is the true differentiator. In a perfect world, your WLAN operates much like your wired Ethernet LAN and requires only an initial install and verification to provide years of faithful service. ![]()
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