WiFi Internet For Buildings and Cities
WiFi networks (802.11) are being implemented to improve productivity, add convenience, and decrease costs. There will soon be new options. AT&T is currently launching WiMax service in major cities in the U.S. New satellite service from EutelSat in Europe, and ViaSat in the U.S., will provide additional options.
If there is high network utilization, today’s wireless LAN products can behave unpredictably. There is a large bandwidth available (83.5 MHz), but even so, the 2.4Ghz frequency band can sometimes become crowded with other 2.4Ghz devices like Bluetooth, microwave ovens, and cordless phones. However, currently, most enterprise WiFi networks have relatively low utilization. In the future, as wireless LANs assume a more central role, interference problems could become more critical.
Key Attributes
High Data Rates. 802.11b: 11 Mbps, uses direct sequence spread spectrum (DSSS) modulation with Complementary Code Keying (CCK). 802.11g, 54 Mbps, uses orthogonal frequency-division multiplexing (OFDM) modulation to increase the throughput. 802.11g systems operate in the same 2.4GHz spectrum as the 802.11b systems and is backward compatible with existing 11b infrastructure. The term used to describe these devices is dual-band. Like 802.11b, 802.11g is limited to three non-overlapping channels. Reasonably priced. Weather Tolerant. Line of Sight is required for longer ranges (more than 1/4 mile). Maximum Wattage for the Transmitter (without FCC licensing) is 1 Watt. Half-Duplex Protocol: the system receives or transmits, but not simultaneously.Access points and wireless routers have an advantage over laptop and desktop cards because they have a higher output power and therefore have the ability to send a signal further then most laptop and desktop cards. When a higher-gain antenna is installed on a desktop card the output power of that device is now increased closer to the output level of the access point or wireless router therefore equaling the two devices. In some cases, the antennas of both the access point/wireless router and the desktop/laptop card may need to be replaced. This is if the distance you are attempting to achieve is greater than the capabilities of the access point/wireless router when using the antennas that came with your card.
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