Appendix B - Wireless Technology
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MVP-7500/8400 Modero Viewpoint Wireless Touch Panels
Overview of Wireless Technology
802.11b/2.4 GHz and 802.11a/5 GHz are the two major WLAN standards and both operate using radio
frequency (RF) technology. Together the two standards are together called Wi-Fi and operate in frequency
bands of 2.4 GHz and 5 GHz respectively.
The 802.11b specification was the first to be finalized and reach the marketplace. The actual throughput
obtained from an 802.11b network will typically be between 4 and 5 Mbps.
Because of the higher frequency (and thus shorter wavelength) that they use, 802.11a signals have a much
tougher time penetrating solid objects like walls, floors, and ceilings. As a result, the price for 802.11a's
higher speed is not only a shorter range but also a weaker and less consistent signal.
802.11g provides increased bandwidth at 54 Mbps. As part of the IEEE 802.11g specification, when
throughput cannot be maintained, this card will automatically switch algorithms in order to maintain the
highest spread possible at a given distance. In addition, 802.11g can also step down to utilize 802.11b
algorithms and also maintain a connection at longer distances.
IP Routing is a behavior of the wireless routing is largely dependent on the wired network interface.
Although the panel can be connected to two networks simultaneously, it may only have one gateway. If the
wired network was successfully set up and a gateway was obtained; then the default route for all network
traffic will be via the wired network. In the event that the wired network was not configured, then the default
route for all network traffic will be via the wireless network. The wired network connection always takes
priority.
Example: Imagine a panel connected to the two networks A & B. A is the wired network and B is the wireless
network. If the Master controller is on either of these networks, then it will be reached. However if the Master
controller is on a different network, C, then the gateway determines which network interface (wired or
wireless) will be used.
Wireless Access Points (WAPs) are the cornerstone of any wireless network. A WAP acts as a bridge
between a wired and wireless network. It aggregates the traffic from all wireless clients and forwards it down
the network to the switch or router. One WAP may be all that is necessary for a standard installation.
However, more WAPs may be needed, depending on the size of the installation, its layout, and its
construction.
Wireless Equivalent Privacy (WEP) Security is a method by which WLANs protect wireless data streams.
A data stream encrypted with WEP can still be intercepted or eavesdropped upon, but the encryption makes
the data unintelligible to the interloper. The strength of WEP is measured by the length of the key used to
encrypt the data. The longer the key, the harder it is to crack.
802.11b implementations provided 64-bit and 128-bit WEP keys. This is known respectively as 64-bit and
128-bit WEP encryption. 64-bit is generally not regarded as adequate security protection. Both key lengths
are supported by the Modero product line.
Whichever level of WEP used, using identical settings is crucial (CASE SENSITIVE)--the key length, and
the key itself-- on all devices. Only devices with common WEP settings will be able to communicate.
Similarly,
If one device has WEP enabled and another does no, they will not be able to talk to each other.
Although the calculations required to encrypt data with WEP can impact the performance of your wireless
network, this impact is generally only seen when running benchmarks, and is not large enough to be
noticeable in the course of normal network usage.