Wi-Fi wireless networks have grown in popularity in recent years and are found ubiquitously in the economy, industry and at home. Wi-Fi networks in the 2.4-GHz Industrial, Scientific and Medical (ISM) band - a public that is not licensed by the FCC. Many types of wireless devices compete with Sky in the 2.4 GHz ISM band - and this leads disorders that adversely affects the performance of a wireless network. A 2.4-GHz spectrum analyzer is the tool of choice forDetection and identification of sources of interference and provision of information, the optimal configuration of a Wi-Fi network allows.

Overview

With wireless systems it is very difficult to predict the propagation of radio waves and the presence of interfering signals without the use of test equipment. Radio waves do not travel the same distance in all directions - instead of walls, doors, elevator shafts, people and other obstacles offer varying degrees of attenuation, theCause of radio frequency (RF) radiation pattern is irregular and unpredictable. To ensure optimum reliability and throughput for your Wi-Fi to (802.11) wireless network it is necessary to recognize and identify sources of interference that may negatively on his performance.

There are a variety of electronic devices, the RF transmission of energy in the airspace. Wi-Fi (802.11 b / g) operates in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band. This particular area ofFrequencies (2.401 GHz to 2.473GHz) is public and their use does not require approval by the FCC. As a result of this band tends to get rather full - not only with 802.11 devices, but also microwave ovens, Bluetooth devices, cordless phones, baby monitors, audio / video transmitters, wireless cameras, etc.

Optimize Professional installers of wireless computer networks to try their customers Wi-Fi network of strategic selection of a subset of the 2.4-GHz band for use by their wirelessNetwork devices. The 2.4-GHz range from 2.401 to 2.473 GHz is divided into 11 each, 22 MHz channels. Note that 2.473GHz - 2.401GHz = 72 MHz, 11 times 22 MHz or 242 MHz. So, how fit is 242 MHz to 72 MHz? Answer - the channels overlap. An installer is the wireless router or access point (AP) be configured to channel 6, used and then all data communication is over the range of frequencies with channel 6 (connected eg 2.426 GHz - 2.448 GHz) occur. But if other wireless devices(802.11 or non-802, 11) are also transmitting on this frequency range will suffer from your wireless network among them. So, if a wireless network or troubleshooting a weak performance is, it is important that a channel that is not subject to interference from other select devices - that is, you do not want your wireless network with other devices compete for the same range of frequencies.

Wi-Fi Diagnostics tool

There are two categories or types of tools thatavailable to help you make the best Wi-Fi channel for your wireless network - WiFi Scanner (ie, 802.11 discovery tools), and 2.4-GHz spectrum analyzers:

Wi-Fi scanner, or 802.11 (WLAN) discovery utility. The best known in this category is NetStumbler (http://www.netstumbler.com/). The discovery tool is the Service Set Identifier (SSID) report for each access point (AP) It recognizes used in conjunction with the channel by the AP. This works is that roughly every 100 msAP sends an "I'm here" beacon - and the discovery tool (on your laptop and with its 802.11 wireless adapter) takes the beacon and adds the SSID to its list. In addition, the discovery may Utility Report SNR (signal-to-noise) ratio for each AP, which as an indication of how close the AP is your current location. Although it is useful information, it does not tell you what not to employ-802.11-devices, and, as the AP. That is, yourLaptop could sit next to a microwave, send all types of RF energy into the room, and the discovery tool would be unaware of its existence. The Discovery program knows only about 802.11 devices - devices which transmit RF energy to the 802.11 protocol - and can not see, not-802, 11 transfers. Here is an analogy - you are in a large auditorium and you hear is someone shouting across the room sometimes, "Hello, I'm Joe!". Joe is an access point, and heOccasionally, a signal can be transmitted to know who's out there, that he is there. It could be that Joe is really busy and talk to many people, or he can be with him. Or there are a lot of noise in the auditorium, it would be difficult to carry on a conversation with Joe from a distance. The discovery tool can not help you with that - only occasionally hears Joe's beacon "Hello, I'm Joe!".

2.4 GHz Spectrum Analyzer. This is the instrument of choicefor detecting and identifying sources of RF interference. Spectrum Analyzer is a fundamental tool for monitoring radio frequency (RF) signals are used - they give you a better picture of the RF environment to help identify and find devices interfering with your wireless LAN (WLAN). As a rule they are based on a 2-dimensional representation, where the vertical axis (Y axis) corresponds to the size of a signal and the horizontal axis (X axis) is the frequency of a signal. Dedicated hardware spectrumAnalyzers can reach the tens of thousands of U.S. dollars they (employ many arrays of analog-digital converter). Recently, PC-based analyzers have appeared on the market. But they are also quite expensive - close to $ 4000 AirSleuth is an affordable 2.4-GHz spectrum analyzer displays available Nuts About Nets, LLC, that RF data in a variety of diagnostic help that you once the presence of interfering devices and then choose the best channel for your wirelessNetwork.

Examples

Click here to see included 5 Examples of measurements with the AirSleuth 2.4-GHz spectrum analyzer. In each picture there are 3 items to take note of:

a. The maximum value on the y-axis

b. The horizontal white lines indicate that the limits of the 11 overlapping channels 802.11

c. The place (ie frequency) and height (relative signal) of the large HF Summit

Figure 1 This figure shows the horizontal whiteLines show the limits of 11, 22 MHz channels in 2.4 GHz band. Note how adjacent channels overlap.

Figure 2 The airspace is relatively quiet and there are no wireless devices transmit in the 2.4 GHz band. Note the maximum value on the y-axis is '3 .0 'relative signal units - that is small. The reason you see peaks (and starting) is not quite flat, the display employs automatic scaling, so that the largest peaks(regardless of how small it really is) fill the screen. We know what looks background noise, since the maximum value on the Y-axis <10.0.

Figure 3 is running a microwave oven. Here you can see that it radiates RF energy over the entire 2.4-GHz band.

Figure 4 A 2.4 GHz cordless phone is switched on. Note the height of the peak in the vicinity of channel 1 is about "140" units and the peak in the vicinity of channel 11to "110" units. These are strong enough to knock out wireless networks are configured to use either channel 1 or channel 11. Moreover, because of the way that channels overlap the first peak would probably also interfere with a wireless network with channel 2, and the second summit would also interfere with wireless networks on channels 9 or 10.

Figure 5 shows the course of the activity from a wireless network (configured so that channel) use 6, as they are activelyTransmitting a large stream.

Leytus Steve is a senior software engineer and develops applications for NutsAboutNets.com. For more information about AirSleuth 2.4 GHz Spectrum Analyzer and other low-cost, PC-based diagnostic tools for the installation, optimization and trouble-shooting 802.11 (Wi-Fi) wireless networks, see http://www.NutsAboutNets . com

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Tags: 802.11, Analyzers, Configure, Networks, Optimally, Spectrum, Troubleshoot, Wireless