Wi-Fi (802.11) are being implemented to improve productivity, providing greater convenience and lower costs. Will soon be new options. AT & T launches WiMax service today in the big cities in the U.S. New satellites Eutelsat and ViaSat in Europe, the United States, to provide additional options.
If there is high network capacity, the current wireless LAN products in unpredictable ways. There is a wide-bandwidth (83.5 MHz),but even so, the 2.4 GHz frequency band are sometimes crowded with other 2.4 GHz devices such as Bluetooth, microwave ovens and cordless phones. But at the moment, many companies have relatively low use Wi-Fi networks. In the future, such as wireless LAN could play a central role interference issues become more critical.
Wireless Network Bridge
Key Attributes
High data rates. 802.11b: 11 Mbps, uses Direct Sequence Spread Spectrum (DSSS) modulationComplementary Code Keying (CCK). It features 54 Mbps 802.11g, Orthogonal Frequency Division Multiplexing (OFDM) modulation to increase throughput. Systems 802.11g operates in the same 2.4 GHz spectrum as 802.11b systems and is compatible with existing infrastructure 11b. The term used to describe these devices, is dual-band. Like 802.11b, 802.11g is limited to three non-overlapping channels. Low cost. Weather tolerant. Line of sight is needed for longer intervals (morethan 1 / 4 miles). Maximum power for the transmitter (no FCC license) is 1 watt. Half-duplex Protocol: The system sends or receives, but not both.
Access points and wireless routers have an advantage over laptops and desktop cards because they have a higher output power and then have the opportunity to send a signal further than most laptops and desktop cards. If an antenna gain higher installed on a desktop card is the output of this device is nowincrease closer to the output level of the access point or wireless router so that it corresponds to the two devices. In some cases, the antennas of the two access points / wireless routers and desktop / laptop card must be replaced. This is where you are trying to find the distance are greater than the capacity of the access point / wireless router, if the antennas supplied with the card.
Wireless network adapters are available in a fewFlavors, including a PCI card for workstations and PC cards for laptops and other mobile devices. Can be exchanged in a decentralized way from client to client mode, or in a central client access point mode. An access point is connected essentially a wireless hub that offers customers the ability to use the wired LAN backbone. In remote mode, the wireless network adapter will be configured with other wireless adapters that are within its range to speak.Distributed client to client (also known as peer-to-peer and white) WLANs are designed for small workgroups that do not have roaming access useful for the backbone LAN. The plug-and-play wireless network adapters make installation easy.
Using more than one access point in a particular area through the use of cellular structures that are similar to your mobile phone service provider coverage area maintained to be facilitated. One of the advantages of roaming mobile users is the ability tofor an access point at hand, the communication between the access point in a cell next roaming.
When connecting two or more buildings, it is better before a wireless bridge between the two points of the spine. If wirelessly within a building when the building-to-building bridges to create, then try to create a wireless network in any building or place. Desktops, laptops and other clientDevices do not function properly if the access point / wireless router, a resident in the building where the access point / router.
Open Line-Of-Sight
802.11b and 802.11g at 2.4 GHz need unobstructed visual Line-Of-Sight (LOS). There should be, landscapes, trees or buildings between the (antenna) points. Radio waves at this frequency does not penetrate metal, steel, cement, stone, etc. However, plaster, plasterboard andWood are usually not a problem.
Around the visual line-of-sight, the "Fresnel zone" is. All the obstacles that are in the Fresnel zone, but not obstruct the view line-of-Sight can slow and hinder affect the signal. The radio waves may deflect off of these obstacles. This is called near-line-of-sight. Even if you can see a light signal with nLoS situations, can reduce the speed of data transfer. A disability that go beyond the visual line-of-Sight and cutsprohibits the visual sight between two antennas in your bridge is considered Non-Line-of-sight.
You may find in your application bridge can visually see each other, the two antennas through spaces and breaks into a tree or prevent the tree line. In addition, time, RF interference, and other site variables to have an effect on the signal.
Security
Extensible Authentication Protocol or EAP is a universal authentication frameworkoften used in wireless networks and Point-to-point. EAP is a mechanism for secure authentication between the client and NAS. EAP can support authentication mechanisms such as tokens, smart cards, passwords and encryption, public key authentication.
802.11i WiFi (802.11g) with more confidence. Authentication mechanisms can be automatically changed frequently to prevent hackers from entering. 802.11n is still in thisthe approval stage, with final approval expected in 2009. Use multiple-input multiple-output (MIMO), a signal processing technique for transmitting multiple data streams through multiple antennas. It provides five times the speed (300 Mbps) and up to twice the range compared to 802.11g. The standard draft is already available, but there is no guarantee that networks built according to the draft 802.11n standard today with a software update for the finalratified standard.
W-CDMA
W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network and where much of the area of mobile broadband voice, if not already existing. W-CDMA is the standard used in UMTS networks, which in many parts of Western Europe, Japan, in use, 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 standarddesigned to support data rates of 144 kbps for use in vehicles, pedestrians and 384 Kbps up to 2 Mbps for indoor use.
The East and the very-near future: LTE and WiMax
In large cities in the U.S., WiMax should be the end of 2008. Sprint's WiMAX commercial debut in Baltimore in September to do. WiMax supports peak data rates of over 20 Mbps, but, as with most technologies in broadband, the bandwidth is shared among users. OnOn average, a user data rate of between 1 Mbps and 4 Mbps is seen.
Most of the major mobile carriers are skipping WiMax, planning instead to build networks with a similar technology called Long Term Evolution (LTE), a successor to current cellular technology. WiMax has a head start on LTE, which is not finished until 2010. These two technologies are like the 4G networks (state of the art mobile technology to access the Internet is like 3G) is called. IfMobile broadband service is important to you, these products can be very attractive. Unlike competitors, GSM and CDMA, both 4G networks, "Orthogonal Frequency Division Multiplexing" (OFDM)-based, sometimes called "discrete multi-tone modulation" means. Since both LTE and WiMax are based on similar technology, a uniform standard is theoretically possible, and calls for the execution. Motorola said that 85% of the technology and work for WiMax equipment will be reused in their projectsfor LTE equipment.
WiMAX and LTE can be a large amount of bandwidth at low power levels to be delivered to mobile devices. Another advantage of WiMax / LTE is its ability to communicate, line-of-sight (unlike conventional WiFi), and communicate in large buildings, in theory making dropped calls, typical for mobile phones today, a thing of the past. A company called MobiTV will use the WiMAX network for the transmission of TV, including HDTV. (VoIP phone Service) is already on WiMAX networks have been used in other parts of the world.
Although WiMax WiMax offers more than 275 installations around the world (mostly small regional operators), is the only place where WiMax has a commercial success in Russia, where existing broadband infrastructure was very poor. In emerging markets without extensive broadband infrastructure (DSL, cable), WiMax, CDMA has an advantage over wireless. Many mobile operators have invested in the current > The networks that develop naturally in W-CDMA.
WiMAX (Worldwide Interoperability for Microwave Access) is similar to cellular coverage, but with Wi-Fi speeds and lower costs. With players such as Intel WiMax chips to produce the way they are integrated into mobile future, there are a lot of money riding on this technology.
(WiMAX) is "the most important thing since the Internet itself." Intel
The WiMax technology allows the operator to build a wireless network> Over a Wide Area Network (city) to enable high-speed Internet connection. As with the first mobile phones, rural areas will be the last, the service can be obtained, but WiMax has a wireless range up to 30 miles.
WiMax supports peak data transfer rate of about 20 Mbps, but like most wireless technologies, the bandwidth is shared among users. The average user data between 1 Mbps and 4 Mbps is seen.
One problem is that the forecasts for WiFiSubscriptions are used to justify the investment in WiMax are too optimistic. Between 15% to 30% of the population would have to sign you subscribe to WiMax, but only 1% to 2% so far Glenn Fleishman, Wifinetnews.com
Wi-Fi networks, including new technologies such as WiMAX and LTE will continue to be frequent in the future. The technique can not be the main obstacle for implementation. Since the same companies that currentlyoperate fixed-line Internet access, the company would invest in large WiFi networks, the reasons are complicated. Competition from new satellite broadband services, such as ViaSat, who are called in the next 2-3 years to life for their products, hopefully.
Internet access for buildings and citieswireless network bridge
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