WiFi networks (802.11), in order to improve productivity, add convenience, cost and valleys. There will soon be new options. AT & T is now the launch of WiMax services in major cities of the new service via satellite Eutelsat United States in Europe and the United States Viasat, will provide further options.
If there is high network utilization, the current wireless LAN products can behave unpredictably. There is a large bandwidth (83.5 MHz), but even then2.4 GHz frequency band can sometimes become more popular with other 2.4GHz devices such as Bluetooth, microwave ovens and cordless phones. However, at present, most business WiFi networks are a relatively low employment. In the future, as wireless LANs a more central role, interference problems may become more critical.
Key Features
High data rates.
802.11b: 11 Mbps using Direct Sequence Spread Spectrum (DSSS) modulation with Complementary Code encoding(CCK).
802.11g, 54 Mbps, uses orthogonal frequency division multiplexing (OFDM) modulation to increase throughput.
802.11g 2.4GHz systems in the same range of 802.11b systems and is compatible with existing infrastructure and 11b. 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 needed for a long series (more than 1 / 4 of a mile).
MassimoPower for the transmitter (no FCC license) 1 Watt.
Half-duplex protocol, the system transmits or receives, but not both.
Access points and wireless routers have an advantage over laptop and desktop cards because they have a higher yield and therefore the ability to send an additional signal most laptops and desktop cards. When a high-gain antenna is installed on a desktop card the output of this device is now closer to a higher productionlevel of the access point or wireless router is the same as the two devices. In some cases, the antennas of both the access point / wireless router and desktop / laptop card must be replaced. This is like the distance you are trying to reach is more than the capacity of the access point / wireless router using the antennas that came with the card.
wireless network cards are available in several flavors, including a PCI card for workstations and PC cards for laptopsand other mobile devices. They may act in a decentralized client-to-client, or in a centralized client-to-access. An access point is essentially a wireless hub that allows clients the ability to attach to the backbone LAN. A decentralized, the wireless network is configured to talk to other wireless network cards to access that are at hand. Distributed client to client (also known as peer-to-peer) WLANs are useful for small work groups to do the roamingdoes not have access to the LAN backbone. The plug-and-play of most wireless network adapters make installation easier.
Using more than one access point in a given area is facilitated by the use of cellular structures, similar to what cell phone providers used to maintain your cover. One of the benefits for mobile users roaming is the ability for an access point automatically hand off the communication to the next access point roaming in a cell.
Inconnecting two or more buildings, it is better to use a wireless bridge, you must first between the two points in the spine. If you want to be wireless within a building when the bridge building-to-building is done, then try to get a wireless network within each building or place. Desktops, laptops and other client devices do not work properly if the access point / wireless router is not resident in the building where the access point / wireless routerlocated.
Unobstructed line-of-Sight
2.4 GHz 802.11b and 802.11g requires free visual Line-Of-Sight (LOS). There should be no trees, soil, or structures between the (antenna) points. Radio waves at this frequency does not penetrate metal, steel, concrete, stone, etc. However, drywall, plaster, wood and usually not a problem.
Around the visual line-of-Sight is the "Fresnel zone". Obstructions that are in the Fresnel zone, althoughnot impede the visual Line-Of-Sight, may also delay, disrupt and reduce the signal. The radio waves may deflect off of such obstacles. This is called Near Line-of-sight. While you might see a slight signal NLOS situations, your data transfer rate to decrease. A barrier that cut the visual line-of-Sight and prohibits an 'optical visual between the two antennas in your bridge is considered as non-line-of-sight.
You can find in your bridge applicationtwo antennas, you can visually see each other through spaces and breaks into a tree to block or line of trees. Also, the time, RF interference, and other site variables have an effect on your signal.
Security
Extensible Authentication Protocol, or EAP, is a universal authentication framework frequently used in wireless networks and point-to-point. EAP can provide a mechanism for secure authentication between client and NAS. Multiple EAPauthentication mechanisms such as token cards, smart cards, passwords, public key encryption and authentication.
802.11i WiFi (802.11g) with enhanced security. Authentication mechanisms are automatically changed regularly, allowing access to hackers.
802.11n, this standard is still pending approval, with final approval expected in 2009. It uses multiple-input multiple-output (MIMO) signal processing technique for transmitting multiple data streams throughmultiple antennas. It provides five times the speed (300 Mbps) and up to two times greater than standard 802.11g. Equipment that meets the draft standard is already available, but there is no guarantee that networks built according to the draft 802.11n standard will be software upgradeable today the final standard is ratified.
W-CDMA
W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network and where many of the mobile broadband sector is heading ifthey have not already. W-CDMA is the standard used in UMTS networks, which are used in most of Western Europe, Japan, and is also used by AT & T Mobility (among other smaller carriers) in America. Verizon has also announced plans for the service.
W-CDMA is a European standard designed to support data rates of 144 kbps for use in vehicles, 384 Kbps for pedestrian use and up to 2 Mbps for indoor use.
It is very near-near future, LTE, andWiMax
In large urban areas in the U.S., WiMax should available late 2008. Sprint will use its commercial WiMAX debut in Baltimore in September. WiMax supports peak data speeds of 20 Mbps, but most of the broadband technologies, that bandwidth is shared among users. On average, a user will see data rates between 1 Mbps and 4 Mbps
Most major carriers have been beaten wireless WiMax, planning instead to build networks using similar technology calledLong Term Evolution (LTE), a successor to current cellular technology. WiMAX has an advantage over LTE, which will not be ready until 2010. These two technologies are referred to as 4G networks (current state of the art mobile phone technology for Internet access called 3G). If the mobile broadband service is important to you, these products are very interesting. Unlike competitors, GSM and CDMA, both 4G networks are based on "Orthogonal Frequency Division Multiplexing (OFDM), alsosometimes referred to as "discrete multi-tone modulation. Since both LTE and WiMax are based on similar technology, a universal standard is theoretically possible, and discussions are ongoing. Motorola said that 85% of technology and Work for WiMax equipment will be reused in its designs for LTE equipment.
WiMAX and LTE can deliver large amounts of bandwidth, such as low power for mobile devices. Another advantage of WiMax / LTE is the ability to communicateline-of-sight (unlike conventional WiFi), and communicate in large buildings, in theory, make a call is dropped, typical of today's cell phones, a thing of the past. A company called MobiTV, the WiMAX network to broadcast TV, including the use HDTV. VoIP (telephony) is already deployed WiMAX networks in other parts of the world.
Although WiMax offers more than 275 WiMAX deployments around the world (mostly regional players to smaller), the only placeWiMax is a real business success in Russia, where the broadband infrastructure was very poor. In emerging markets without extensive broadband infrastructure (DSL, cable), WiMax has an advantage over W-CDMA. Many mobile operators have invested in existing networks that naturally evolve into W-CDMA.
WiMax (Worldwide Interoperability for Microwave Access) will be similar to cellular coverage, but with Wi-Fi connection speeds and lower costs. With players like Intel leadingways to ensure the WiMax chip integrated into future laptops, there's a lot of money riding on this technology.
(WiMax) "the most important since the Internet itself." Intel
WiMax technology allows an operator to build a wireless network over a wide area (city), which enables high-speed connections to the Internet. As with the first mobile phone coverage in rural areas will be the last to receive the service, but WiMax has a communication range of up to 30miles.
WiMax supports peak data speeds of 20 Mbps, but with most wireless technologies, that bandwidth is shared among users. The average user will see data rates between 1 Mbps and 4 Mbps
One problem is that the forecasts for Wi-Fi subscriptions used to justify the investment in WiMax are too optimistic. Between 15% to 30% of the population of a territory should sign up for WiMax, but only 1% to 2% is now subscribe to GlennFleishman, Wifinetnews.com
WiFi networks, including newer technologies such as WiMax and LTE will continue to become more prevalent in the future. The technology can not be the main obstacle to implementation. Because the same companies that currently operate in line Internet access land, would allow companies to invest in large WiFi networks, the reasons are complicated. Competition from new broadband services via satellite, such as ViaSat, which will belaunched over the next 2-3 years will be their products, hopefully.
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