ired for enterprise WLAN service. User devices that are equipped with the following: - Virtual Private Network (VPN) software that enables the network to treat wireless devices differently. - Personal firewalls to prevent hackers from accessing data on laptops, notebooks, and personal digital assistants. - WPA2, which is strong 128-bit encryption to prevent eavesdropping (128-bit encryption refers to encryption with a choice 128 combina- tions of zeros and ones for every bit that is encrypted). This is also referred to as Advanced Encryption Standard (AES). Access points. The LAN. Applications. The complexity is due to the fact that software on the user device, the access point, controllers, and security servers must all match. In addition, enterprises have the fol- lowing tasks: Distribute client software to each user's device. Check for rogue access points. Enter names in databases. Wi-Fi Standards, Architecture, and Use in Cellular Networks Use a strong authentication method such as a Remote Authentication Dial- In User Service (RADIUS) server with Authentication, Authorization, and Accounting (AAA) capability. Monitor usage. Ensure that portable devices don't spread viruses to the corporate network that they might have picked up from e-mail attachments or the Internet. When corporations use WPA2, employees' laptops won't be compatible with cor- porate networks unless their home 802.11 networks also use WPA2. Using Wi-Fi to Offload Traffic from Congested Mobile Networks To ease congestion caused by increased tablet and smart phone traffic, carriers often supplement mobile services in densely populated areas with Wi-Fi in airports, train stations, and cafés where mobility is not required. In addition, Wi-Fi hotspots relieve backhaul congestion by transmitting traffic over broadband links rather than on the mobile network. Wi-Fi equipment is less costly than base stations in mobile networks and spec- trum is free. While cellular service excels at covering large areas, Wi-Fi service does extremely well at providi