15.4 Wireless LAN 802.11 Evolution
| 802.11-based wireless LAN networks are gaining in popularity and being deployed on a wide scale. The lure of high-speed and low-cost wireless Internet access is an enabler in itself. The other primary drivers for this phenomenon are as follows :
802.11 access points and networks are primarily being deployed in home networks and communities, enterprises of all sizes, and public hotspot areas such as airports, hotels, and convention centers. As the number of users with laptops and PDAs grows, access to the Internet via these hotspot networks will increase. Notebook computer manufacturers have begun to incorporate wireless LAN functionality into computers. Some of the newer PDAs are also beginning to incorporate 802.11b functionality as a standard feature. 15.4.1 Wireless LAN Technology EvolutionFrom a technology evolution perspective, 802.11 technology has come a long way. From the 2-Mbps standard to the 11-Mbps standard (802.11b) to 45 Mbps (802.11g) and 54 Mbps (802.11a), the increase in the data speeds has been impressive. Access points and interface cards based on 802.11a are already becoming commercially available.
What is the future for an increasingly popular technology? Market pressures are forcing vendors and operators to increase the bandwidth/data rates offered by wireless LANs as well as provide enhanced security. In order to achieve even higher data rates, on the order of 100s of Mbps, new coding schemes, error correction, and operating frequencies will be developed. Antenna technology will also help resolve deployment issues that are currently faced in real life networks. One of the drawbacks of the current 802.11 systems is the lack of security. As has been described in the chapter on 802.11, WEP is a nonstarter for securing networks. This is being worked on in the IEEE by Task Group i, and a more secure solution is expected to be standardized in the near future. The Advanced Encryption Standard (AES) is expected to be standardized for securing the air interface. The work on security is being done in Task Group I of the IEEE 802.11 work area. Current 802.11 networks do not support quality of service. In order to support real-time services such as voice and video, QoS will be a requirement. Work on QoS is currently being standardized in Task Group E. Current WLAN networks allow a user to move within the same subnet. However, movement across subnets will be a requirement in the near future. One solution to address such mobility is based on the use of mobile IP. We can envision the use of mobile IP on top of wireless LAN networks to provide seamless mobility across subnets of WLAN access networks. 15.4.2 Wireless LAN Service EvolutionWireless LAN service in the enterprise is becoming more accepted. IT departments recognize the vulnerability of WLAN security based on WEP. Hence they have resorted to other means of securing networks deployed within the campus. One such means is to use a virtual private network (VPN) solution. The WLAN access points are deployed outside a VPN gateway and hence are not directly connected to the enterprise LAN. Users gain access to the enterprise LAN over a VPN that is between the terminal/device/notebook computer to the VPN gateway and that allows valid users access to the LAN. Since all the data traffic is now carried over the VPN tunnel (which is IPsec secured), the threat of snooping on the air interface is mitigated. Other solutions for securing include proprietary ones such as Cisco's Lightweight Extensible Authentication Protocol (LEAP) for enhanced security. 15.4.3 Operator Wireless LANTraditional cellular operators are beginning to deploy WLAN networks on a nationwide basis. Some examples include Voicestream's wireless LAN network in the United States and mm02's plans for deployment in the United Kingdom. WLAN access points are generally deployed in hotspot areas such as train and bus stations , airports, cafes and restaurants , stadiums, and shopping malls. These networks are referred to as public wireless LAN or operator wireless LAN networks. In order to access these networks, subscribers need to have a subscription to the service and authenticate themselves before access is allowed. The ISP model has used authentication mechanisms and protocols based on Radius for this purpose. Nokia has also developed a solution that allows the users to authenticate themselves using a SIM (subscriber identity module). Since many mobile users already have a subscription for their mobile telephones with an operator, the same subscription can be used to access these WLAN networks. A view of the architecture that utilizes the GSM network's SIM-based authentication infrastructure for WLAN access is shown in Figure 15-9. Figure 15-9. WLAN access with GSM authentication infrastructure. The benefits of such a solution to operators are manyfold and include the following:
End users benefit from the fact that they do not need to have multiple subscriptions for different services. Their existing GSM subscription with an operator will allow them to access WLAN networks provided by the user's service provider or by any other operator who is also a GSM operator with whom the user's service provider has roaming agreements. 15.4.4 WLAN Service as Another Access Technology in 3G802.11-based networks are now being considered as another access type for 3G networks. In the UMTS architecture the two access technologies that are specified today are the UTRAN and GERAN. 3GPP is currently working on specifying WLAN as another access type as well. With the introduction of WLAN as another access type, users will be able to access the same services that they are used to from their mobile phone/terminal when using the WLAN medium. This work is expected to be completed in the R6 specification of 3GPP.  |
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