How to use AirBears
Guest Accounts
Reporting Problems
Wireless LAN Project
Locations
Map
FAQ
AirBears Poster
AirBears usage statistics
UCCSC 2002 presentation
General References

Data Network Home
Contact Information

CNS websites A-Z list
CNS staff directory

Data Services Internal | CNS Internal
Last revised: July 27, 2004
Technical inquiries: nsweb@berkeley.edu

AirBears: the Wireless LAN Project

Wireless LAN standard and configuration

• The current wireless lan standard is IEEE 802.11b DSSS, operating in the 2.4GHz range. (DSSS stands for Direct Sequence Spread Spectrum.) The 802.11b standard allows users to share up to a theoretical 11 Mbps. In actual use, this rate will vary, but it may not exceed 5 Mbps, due to the considerable overhead in the wireless protocol.

• The basic wireless infrastructure network consists of access points (APs) and wireless adapter cards. Client cards for laptops come in PCMCIA-format; for desktops, as PCI cards. The access point (aka a 'base station') is a transmitter/receiver that is connected to the wired network, acting as a bridge between the wired and and wireless network. The device is usually wall- or ceiling-mounted, positioned so as to provide the optimum coverage for laptops with wireless NICs. The range of coverage will vary depending upon location, type of building material and surrounding surfaces, with most estimates from 100 to 500 feet indoors, and up to 1000 feet outdoors with no obstructions. Use of additional antennas may extend the range, or improve the quality of the signal.

  The AP determines if a wireless device is allowed on the network using some form of authentication, and if the device is authorized, will associate it to that AP.

Supported Protocols, Platforms, Wireless Cards

• For the pilot implementation, we plan to support PC and Macintosh laptops, under different OS's. Support for PDAs and other hand-held wireless lan devices will be evaluated for future implementation.

• The wireless network will provide IP-only services. IPX and AppleTalk will not be supported.

• Any WiFi ('wireless fidelity') compliant card should work with AirBears. Equipment that is WiFi- compliant is certified by the WECA (Wireless Ethernet Compatibility Alliance). See the FAQ for a list of cards that have we've tested with AirBears.

• Authentication - how to validate users authorized to use the service

  Access to AirBears is restricted to members of the campus community who have a valid CalNetID and passphrase as well as sponsored visitors with a valid guest account.

  AirBears uses a web-based authentication scheme to authenticate a wireless session. Users open an SSL-enabled web browser to any page, and will be redirected to the AirBears login page, where they need to enter either their CalNetID and passphrase or guest account and password. If authenticated, the user will be redirected to their original web page. This method has the advantage of not requiring additional client software or firmware upgrades (most everyone has a web browser available), nor is it vendor-specific.

  The AirBears guest account service allows Faculty and Staff to create temporary accounts for campus visitors.

• Encryption - how to protect wireless data streams from eavesdroppers

  The 802.11 security standard, WEP (Wired Equivalent Privacy), has been shown to have inherent flaws that render it largely useless, particularly for large-scale deployment. WEP relies on a shared key ('password') between the access point and the client for encryption/decryption. Unfortunately, this is usually a single key which all prospective users must share, which means that the password is no longer very private. A well-publicized study done by the ISAAC research group in the UC Berkeley Computer Science department points out numerous flaws in the WEP approach.

  Some vendors (e.g., Cisco and Lucent) have recently come out with 'dynamic' WEP algorithms that dynamically allocate keys on a per-user, per-session basis. However, these schemes are vendor-specific, so they won't interoperate with other vendor's client cards.

  At least for the pilot deployment, there will be no support for encryption over the wireless network. Instead, it is strongly recommended to use application-layer encryption. For example, to login to UNIX accounts, use ssh or kerberized-telnet, not telnet; when providing personal or confidential data on the web, make sure the page is https (not http) secure; for mail, use BearMail, not Eudora or any mail program that uses unencrypted POP or IMAP. System administrators should protect their applications by allowing connections only from encrypted sessions.

• Roaming

  Seamless roaming is the ability to move from one AP coverage area to another without losing connectivity. The pilot coverage areas are discontinguous, so connectivity will be lost if one moves from one coverage area to another. Support for roaming is very limited at this time, but experience gained during the pilot should help determine whether full-scale roaming capability is critical.

• Interference with other wireless equipment

  The 2.4GHz spectrum is unlicensed and used by other wireless devices. Known conflicts include 2.4GHz cordless phones (e.g. Panasonic), and some older makes of microwave ovens. Furthermore, some laboratory equipment operating within the same frequency range may also cause interference. The campus must determine who 'owns' the airspace, and come up with ways to regulate its use in the case of conflict.

  Some departments or units may have already installed wireless lan equipment (e.g., Apple Airport base stations). If the campus extends wlan service to include a coverage area with existing local wlan equipment, the campus will claim right of 'eminent domain' and ask that the local equipment be removed. (Note: local wlan equipment that is connected to a non-private, shared ethernet network, is already, strictly speaking, out of compliance with campus policy for user-installed network equipment.)

  Other wireless technology, such as Bluetooth, also use the 2.4GHz range, another potential source of conflict.

• User privacy

  NTTMCL is interested in tracking usage patterns of wireless users; as part of the pilot phase, user mobility patterns will be collected. User identities will remain anonymous. No personal information will collected as part of this data collection. This monitoring activity will need the approval of the Committee on Human Subjects.

We have been working closely with the Offices of Environmental Health & Safety, and Radiation Safety to ensure that the wireless equipment deployed and/or recommended will be fully compliant with campus safety regulations and will pose no known health hazards to the community at large.

There has been extensive research done on the safety of exposure to radio frequencies. Manufacturers of wireless LANs must meet stringent government and industry regulations for safety. The output power of wireless LAN systems is very low, much less than that of a cellular phone. Since radio waves fade rapidly over distance, there is very little exposure to radio frequencies to those in the area of a wireless LAN. No adverse health affects have ever been attributed to wireless LANs.

For more information, visit the web site of the Wireless LAN Association

The pilot testbed sites represent a cross-section of campus areas that may benefit from wireless access. The different areas include library study areas, lecture halls, cafe/restaurant space, offices, lounges, and outdoor space. Other areas may include labs and conference rooms. The long-term plan is to blanket an area with overlapping AP coverage so that users can roam between AP 'cells' without losing connectivity.

Phase 1 sites:

• Haas Business school (selected locations)
• Doe Library carrels, study areas (selected)
• Northgate lecture hall
• Bechtel Library study area
• Free Speech Movement Cafe
• Cesar Chavez (selected locations)
• Foothill Residence Hall (selected locations)

Coverage will be extended to other parts of campus as appropriate. Suggestions for future sites (preferably areas that serve a large number of users) can be sent to the airbears-wireless mailing list.

• User Support

  During the pilot phase, user support will be provided by the airbears-wireless mailing list. To subscribe to the list, send email to Majordomo@listlink.berkeley.edu and type the command "subscribe airbears-wireless" in the body of the message.

  For help with installing a wireless card, students can receive help after November 1, 2001 at the Student Computer Consulting Service. Faculty and staff should contact their departmental IT staff or Dr. Micro as appropriate.

• Vendor Support

Costs

The pilot service will be provided free of charge until at least the end of fiscal year 2001. Participants will need to purchase a wireless network card. Laptop 802.11b cards are available for under $100.