Wi-Fi with a PS Twist sounds like a new drink and in some ways it can be very intoxicating. There is no lack of acronyms in the communications business, but few of them have hit the industry with as much potential impact as Wi-Fi. Yet many may not be aware of what Wi-Fi is or how it is already impacting Public Safety.

Wi-Fi stands for the implementations of the 802.11 suite of standards (a, b, g etc.). In plain language, it is the radio link for many classes of service hooking you up to the wired world of the Internet or private LANs (computer Local Area Networks). It is a mobile environment where you are not tied to an umbilical cable to obtain and provide information. Some of the services that can be delivered in the Wi-Fi environment include things as mundane as your email and classic Internet browsing to music and video on the air. It can be a public network scenario or a private network scenario. It is one of those relatively inexpensive (cheap) hardware implementations that public safety would love to be able to capitalize on to provide other mobile, but high volume data requirements unique to the public safety environment.

In actuality, public safety is already using the commercial flavor of Wi-Fi. Several agencies around the country are already implementing “hotspots” to create mobile environment networks to service MDT (Mobile Data Terminal) operations providing the work force with connectivity that previously was limited to the office. Such things as mug shots and video to and from the vehicle become possible. However, those agencies need to be very cautious. Wi-Fi as it now exists works in a very, very open environment. There are security concerns (which do have solutions), but worse, Wi-Fi (802.11a, b, and g) work in a frequency band that is unlicensed. That means it is being shared with many other private and commercial Wi-Fi providers as well as garage door openers, cordless phones, and other totally unregulated devices. Sure, these devices have power and emission limits, but they can provide a significant amount of noise in the same RF environment and can be detrimental to a critical resource for a public safety agency.

The FCC to the rescue. The promises of broadband services as describe above are many and great. The downside is the shared aspect of the band. What if public safety could get the same functionality as Wi-Fi, but put it in a band of spectrum that is exclusive to public safety? Sounds great and that is exactly what is happening right now. The FCC has allocated a significant amount of spectrum at 4.9 GHz for just this type of implementation. There are public safety groups working closely with the manufacturing community, federal interests, and standards bodies to create a “tweaked” 802.11 series standard that includes all of the functionality of Wi-Fi, but operating at a frequency that is exclusive to public safety.

The potentials are enormous. Public safety technology usually takes a back seat to the exploding commercial market in the wireless world. This translates to significant cost to public safety because public safety can not provide a market nearly as large as the commercial market. In this case, public safety can take advantage of the development in the commercial market and with very little alteration, make it work in our own field.

For those of us in the public safety environment, all of those high tech applications you have heard of and perhaps wished for and have actually seen in the commercial world, may now be within grasp. Not only technically, but also financially.

List of 802.11 standards:

IEEE 802.11 WIRELESS ETHERNET STANDARDS SUMMARY

Task Group	Status
a	The original high-speed standard; 54 Mbits/s using OFDM in the 5 GHz; ratified.
b	The initial and primary defining standard; 11 Mbits/s using DSSS in the 2.4-GHz band; ratified; used in most (90%+) WLAN products and activities.
e	Goal is to improve the MAC and improve and manage QoS, provide classes of service, and enhance security and authentication. It should facilitate applications such as VoIP over wireless. Ratification expected in the third quarter of this year.
f	Inter-Access Point Protocol (IAPP) development; permits access points to communicate with one another to facilitate roaming, LAN-to-LAN handoffs, and links to other systems; essential as the number of access points grows; a work in progress.
g	High-speed extension of the 802.11b standard; implements speeds to 54 Mbits/s in the same 2.4-GHz bandwith backward compatibility with 802.11b products; ratification expected in June/July 2003.
h	Modifications to the 802.11a standard to implement changes that will permit its use in Europe; MAC and HY changes to implement spectrum and power-management features compatible with European standards; ratification expected later in 2003.
i	Project to enhance security of transmission in a/b/g radios; improves encryption by using the AES with 64- and 128-bit keys and authentication methods over the original Wireless Equivalent Protocol originally built into the a and b standards; ratification expected in 2004.
j	Modification to 802.11a standard to add 4.9- to 5-GHz channel-selection capability so that the system is usable in Japan.
k	Project to define Radio Resource Measurement enhancements to provide interfaces to higher layers for radio and network measurements; adds load balancing, roaming, and co-existence, plus other management and measurement features.
m	An ongoing maintenance-related task group to watch over, update, and correct the main a, b, and g PHY and MAC standards.
n	The High Throughput Study Group tasked to speed up the MAC to permit future faster, next-generation options.

Public Safety - 4.9 GHz Rules Summary

Effective July 30, 2003, the FCC will accept applications for 4.9 GHz applications

Licensing will be based on what is called a “jurisdictional licensing scheme”. This interprets as any eligible agency may obtain a license that covers their legal jurisdictional area of operation. Coordination is not required to obtain a license. The FCC is relying on local entities to coordinate the use of this spectrum in any given area where multiple governmental agencies may have overlapping service areas. Agencies may apply directly to the FCC for licenses. Applicants will have the opportunity to apply directly through ULS online to the FCC. It is unclear yet if the services of one of the coordinators that is capable of submitting applications electronically to the FCC will be enabled by the FCC. The FCC no longer accepts hard copy applications for any Part 90 licenses. FCC sources indicate a notice of licensing procedures is forthcoming.

The Rules for 4.9 GHz are in Subpart Y in 47CFR Part 90. Eligibility is explained in section 90.1209. While formal pre-application formal coordination is not required, for locations north of line A or east of line C (Canadian vicinities) may require coordination with Canada (which will be handled by the FCC after the fact of filing an applications).

Licensees will have the authority to operate on any authorized channel in the band within its licensed area of operation (legally described political jurisdiction). Agencies may strike an agreement with non public safety eligible agencies in order that such non-classic public safety agencies providing services that affect the protection of life and critical functions.

Licensees will have the authority to construct and operate any number of base stations anywhere within the area authorized on their license. However, a station will be required to be individually licensed if it is located where an international agreement is required, it requires an environmental assessment (see Part 90 Section 1.1307), and the location would affect a radio quiet zone (1.924). Any station that requires an FAA notification must be registered with the Commission prior to construction.

Licensing authority allows the operation of base and mobile units and temporary (1 year or less) fixed stations. Licensees may operate either base or mobile equipment outside of their jurisdiction with the approval of a licensee within the remote jurisdiction.

The grant of a basic jurisdictional area license does not give the licensee authority to operate point-to-point fixed stations. Such fixed stations must be licensed individually on a site-by-site basis and will only be authorized on a secondary, non-interference base with jurisdictionally licensed operations.

Sharing and coordination. Channels in this band will not be granted exclusive use and must be implemented on a shared basis only. All co-located licensees shall cooperate I the selection and use of channels. Any situations of interference are expected to be resolved by the parties involved. If licensees are unable to resolve any issues, the commission may impose restrictions to any of the parties.

There is no time limit for construction and operation of base and temporary fixed operation. Site specific licenses are required to be placed in operations within 18 months of the grant.

The FCC has requested Regional Planning groups designed to facilitate operation and cooperation for each region within 12 months of the effective date of the rules.

There are 18 channels which be aggregated for channel bandwidths of 1, 5, 10, 15, or 20 MHz. Channels 1 – 5 and 15-18 are 1 MHz channels and 6-14 are 5 MHz channels. Power limits vary from 20 dBm to 33 dBm depending on bandwidth.

The full FCC text of the 4.9 GHz Rules are posted on the APCO-AFC Web site and can be found listed under “4.9 GHZ – Broadband Technology for Public Safety” (http://www.apco911.org/frequency/issues.htm).