| WiFi networks (802.11) are being implemented to | | | | NAS. EAP can support multiple authentication |
| improve productivity, add convenience, and | | | | mechanisms, such as token cards, smart cards, |
| decrease costs. There will soon be new options. | | | | passwords, and public key encryption |
| AT&T is currently launching WiMax service in | | | | authentication. |
| major cities in the U.S. New satellite service from | | | | - 802.11i is WiFi (802.11g) with better security. |
| EutelSat in Europe, and ViaSat in the U.S., will | | | | Authentication mechanisms are automatically |
| provide additional options. | | | | changed frequently, preventing hackers from |
| If there is high network utilization, today's wireless | | | | gaining access. |
| LAN products can behave unpredictably. There is | | | | - 802.11n, this standard is still in the approval |
| a large bandwidth available (83.5 MHz), but even | | | | stage, with final approval expected in 2009. It |
| so, the 2.4Ghz frequency band can sometimes | | | | uses multiple-input multiple-output (MIMO), a signal |
| become crowded with other 2.4Ghz devices like | | | | processing technique for transmitting multiple data |
| Bluetooth, microwave ovens, and cordless phones. | | | | streams through multiple antennas. It offers five |
| However, currently, most enterprise WiFi | | | | times the throughput (300 Mbps) and up to twice |
| networks have relatively low utilization. In the | | | | the range compared to the 802.11g standard. |
| future, as wireless LANs assume a more central | | | | Equipment meeting the draft standard is already |
| role, interference problems could become more | | | | available, but there is no guarantee that networks |
| critical. | | | | built under today's 802.11n draft standard will be |
| Key Attributes | | | | software upgradeable to the final ratified standard. |
| - High Data Rates. | | | | W-CDMA |
| - 802.11b: 11 Mbps, uses direct sequence spread | | | | W-CDMA (Wideband Code Division Multiple |
| spectrum (DSSS) modulation with Complementary | | | | Access) is a type of 3G cellular network and |
| Code Keying (CCK). | | | | where much of the mobile broadband industry is |
| - 802.11g, 54 Mbps, uses orthogonal | | | | heading if they aren't already there. W-CDMA is |
| frequency-division multiplexing (OFDM) modulation | | | | the standard used in UMTS networks, which have |
| to increase the throughput. | | | | been deployed in much of Western Europe, Japan, |
| - 802.11g systems operate in the same 2.4GHz | | | | and is also used by AT&T Mobility (among |
| spectrum as the 802.11b systems and is | | | | other smaller carriers) in America. Verizon has also |
| backward compatible with existing 11b | | | | announced plans for service. |
| infrastructure. The term used to describe these | | | | W-CDMA is a European standard designed to |
| devices is dual-band. Like 802.11b, 802.11g is limited | | | | support data transmission rates of 144 Kbps for |
| to three non-overlapping channels. | | | | use in vehicles, 384 Kbps for pedestrian use and |
| - Reasonably priced. | | | | up to 2 Mbps for use indoors. |
| - Weather Tolerant. | | | | The Near and the Very-Near Future: LTE, and |
| - Line of Sight is required for longer ranges (more | | | | WiMax |
| than 1/4 mile). | | | | In major metropolitan areas in the U.S., WiMax |
| - Maximum Wattage for the Transmitter (without | | | | should available late in 2008. Sprint will make its |
| FCC licensing) is 1 Watt. | | | | commercial WiMAX debut in Baltimore in |
| - Half-Duplex Protocol: the system receives or | | | | September. WiMax supports peak data speeds of |
| transmits, but not simultaneously. | | | | about 20 MBPS, but, as with most broadband |
| Access points and wireless routers have an | | | | technologies, that bandwidth will be shared |
| advantage over laptop and desktop cards | | | | amongst users. On average, a user will see data |
| because they have a higher output power and | | | | rates between 1 MBPS and 4 MBPS. |
| therefore have the ability to send a signal further | | | | Most major wireless carriers are skipping WiMax, |
| then most laptop and desktop cards. When a | | | | planning instead to build out networks using a |
| higher-gain antenna is installed on a desktop card | | | | similar technology called Long Term Evolution |
| the output power of that device is now increased | | | | (LTE), a successor to current cellular technology. |
| closer to the output level of the access point or | | | | WiMax has a head start on LTE, which won't be |
| wireless router therefore equaling the two | | | | ready until 2010. These two technologies are |
| devices. In some cases, the antennas of both the | | | | referred to as 4G networks (Current state of |
| access point/wireless router and the desktop | | | | the art mobile phone technology for accessing the |
| laptop card may need to be replaced. This is if | | | | Internet is called 3G). If mobile broadband service |
| the distance you are attempting to achieve is | | | | is important to you, these products will be very |
| greater than the capabilities of the access point | | | | attractive. Unlike rivals GSM and CDMA, both 4G |
| wireless router when using the antennas that | | | | networks are based on "Orthogonal Frequency |
| came with your card. | | | | Division Multiplexing" (OFDM), also sometimes |
| Wireless network cards come in a couple of | | | | referred to as "discrete multi-tone modulation". |
| flavors, including a PCI card for workstations and | | | | Since both LTE and WiMax are based on similar |
| PC cards for laptops and other mobile devices. | | | | technology, a unified standard is possible in theory, |
| They can act in a decentralized client-to-client | | | | and discussions are ongoing. Motorola has said |
| mode, or in a centralized client-to-access point | | | | 85% of the technology and work for WiMax |
| mode. An access point is essentially a hub that | | | | equipment will be reused in its designs for LTE |
| gives wireless clients the ability to attach to the | | | | equipment. |
| wired LAN backbone. In a decentralized mode, the | | | | WiMAX and LTE can deliver large amounts of |
| wireless network card is configured to talk with | | | | bandwidth operating at the low power levels |
| other wireless network access cards that are | | | | necessary for mobile devices. Another advantage |
| within its range. Decentralized client-to-client (also | | | | of WiMax/LTE is its ability to communicate out of |
| know as peer-to-peer) WLANs are useful for | | | | line-of-sight (unlike conventional WiFi), and to |
| small roaming workgroups that do not require | | | | communicate into large buildings, in theory making |
| access to the LAN backbone. The plug and play | | | | dropped calls, typical of today's cell phones, a thing |
| capabilities of most wireless network cards make | | | | of the past. A company called MobiTV will utilize |
| setup easy. | | | | the WiMAX network for the broadcast of TV, |
| The use of more than one access point in a given | | | | including HDTV. VoIP (telephone service) has |
| area is facilitated by the use of cell structures, | | | | already been deployed on WiMAX networks in |
| which are similar to what mobile phone providers | | | | other parts of the world. |
| use to maintain your coverage area. One of the | | | | Although the WiMax boasts over 275 WiMax |
| benefits to roaming mobile users is the ability for | | | | deployments throughout the world (mostly small |
| one access point to automatically hand off | | | | regional operators), the only place where WiMax |
| communication to the next access point in a | | | | has been a business success is in Russia, where |
| roaming cell. | | | | existing broadband infrastructure was very poor. |
| When connecting two or more buildings it is best | | | | In emerging markets without extensive |
| to first establish a wireless bridge between the | | | | broadband infrastructure (DSL, cable), WiMax has |
| two points in the backbone. If you want to be | | | | an advantage over W-CDMA. Many cell-phone |
| wireless within a building, once the | | | | operators have invested in existing networks that |
| building-to-building bridge is created, then attempt | | | | naturally evolve into W-CDMA. |
| to establish a wireless network within each building | | | | WiMax (Worldwide Interoperability for Microwave |
| or location. Desktops, laptops, and other client | | | | Access) will be similar to cellular coverage, but |
| devices will not work reliably if the access point | | | | with Wi-Fi's speed and lower cost. With players |
| wireless router is not resident in the building where | | | | like Intel leading the way to make sure WiMax |
| the access point/wireless router is located. | | | | chips are built into future laptops, there is a lot of |
| Unobstructed Line-Of-Sight | | | | money riding on this technology. |
| 802.11b and 802.11g at 2.4GHz requires | | | | - (WiMax is) "the most important thing since the |
| unobstructed visual Line-Of-Sight (LoS). There | | | | Internet itself." Intel |
| should not be trees, terrain, or structures | | | | WiMax technology will allow an operator to build a |
| between your two (antenna) points. Radio waves | | | | wireless network over a large area (city) that will |
| at this frequency will not penetrate metal, steel, | | | | allow high-speed connections to the Internet. As |
| concrete, stone, etc. However, dry wall, sheet | | | | with early cell phone coverage, rural areas will be |
| rock, and wood usually are not a problem. | | | | the last to receive service, but WiMax has a |
| Surrounding the visual Line-Of-Sight is the "Fresnel | | | | communication range of up to 30 miles. |
| zone". Any obstructions that come into the | | | | WiMax supports peak data speeds of about 20 |
| Fresnel zone, although not obstructing the visual | | | | Mbps, but, as with most wireless technologies, |
| Line-Of-Sight, may also slow down, hinder and | | | | that bandwidth will be shared amongst users. The |
| affect your signal. The radio waves may deflect | | | | average will see user data rates between 1 Mbps |
| off of those obstructions. This is called Near | | | | and 4 Mbps. |
| Line-Of-Sight. Although you may see a slight signal | | | | One problem has been that forecasts for WiFi |
| with nLoS situations, your data transfer rate may | | | | subscriptions used to justify the investment in |
| decrease. An obstruction that cuts across the | | | | WiMax have been overly optimistic. Between 15% |
| visual Line-Of-Sight and prohibits an optical visual | | | | to 30% of an area's population was expected to |
| between the two antennas in your bridge is | | | | subscibe to WiMax, but only 1% to 2% have |
| considered Non-Line-Of-Sight. | | | | subscribe so far according to Glenn Fleishman, |
| You may find in your bridge application that the | | | | WiFi networks, including the newer technologies |
| two antennas can visually see each other through | | | | like WiMax and LTE, will continue to become more |
| spaces and breaks in an obstructing tree or tree | | | | prevalent in the future. The technology may not |
| line. Additionally, weather, RF interferences, and | | | | be the most important impediment to |
| other site variables can have an effect on your | | | | implementation. Because the same companies that |
| signal too. | | | | currently operate land-line internet access, would |
| Security | | | | be the companies to invest in large scale WiFi |
| Extensible Authentication Protocol, or EAP, is a | | | | networks, the motivations are complicated. New |
| universal authentication framework frequently | | | | competition from broadband service satellites, like |
| used in wireless networks and Point-to-Point | | | | ViaSat, that will be launched in the next 2-3 years |
| connections. EAP can provide a secure | | | | will prod them on, hopefully. |
| authentication mechanism between the client and | | | | |