The Differentiation between 802.11 WiFi standards:

802.11a
802.11b
802.11d
802.11e
802.11f
802.11g
802.11h
802.11i

Commentary

What to Expect From 802.11 Wireless LAN Standards and When Standards for wireless networks have stimulated adoption but left many vendors in confusion. Gartner summarizes the main standards in the IEEE’s 802.11 series. After 13 years of proprietary products and ineffective standards, the networking industry has finally decided to back one set of standards for wireless networking: the 802.11 series from the Institute of Electrical and Electronics Engineers (IEEE). These emerging standards define wireless Ethernet, or wireless LAN (WLAN).

About 60 vendors supply more than 200 different products for WLANs. Sales are expanding rapidly as an increasing number of enterprises see the value of WLANs. Growth has been helped by the Wireless Ethernet Compatibility Alliance (WECA), which provides conformance and interoperability testing. So far, this group of more than 130 companies has granted its “Wi-Fi” label of approval to more than 185 products conforming to the 802.11b standard.
Outside the United States, other standards bodies have also worked to standardize wireless data networking. The European Telecommunications Standards Institute (ETSI) developed HyperLAN/2 for wireless LANs working at 5GHz that met regulations for working in that radio band, which is used for radar in Europe. HyperLAN/2 has not achieved the market momentum of the IEEE series. In Japan, the Multimedia Mobile Access Communication (MMAC) Systems Promotion Council group is developing specifications for advanced types of wireless systems. However the IEEE is developing additional standards to meet Japanese regulatory guidelines, and therefore MMAC is also unlikely to meet the market momentum of the IEEE series.
Within the IEEE’s 802.11 series there are several specifications, some complete and some still under development. Users need to decide which are important; manufacturers need to decide which to include in products; resellers need to select which products to support and recommend; and service providers need to decide which to deploy in services.

Summary of the IEEE 802.11 Standards:
There are two physical layer standards: 802.11b operating in the 2.4GHz radio band and 802.11a operating in the 5GHz radio band.
Products complying with 802.11b, or only 11b, shipped in volume through 2001. Products complying with 11a started to appear in North America toward the end of 2001. A third physical layer specification, 11g, is in the final stages of being defined (see Table 1). In many other countries, including those in Europe, regulators of radio spectrum block the use of 11a products operating in the 5GHz radio band.

Other 802.11 standards are being developed that extend the physical layer options, improve security, add quality of service (QOS) features or provide better interoperability. Vendors are likely to offer
proprietary implementations of these features before the IEEE finalizes the standards.


802.11a pil
Description: A physical layer standard for WLANs in the 5GHz radio band. It specifies eight available radio channels (available radio spectrum in some countries would permit the use of 12 channels).
Maximum link rate of 54-Mbps per channel, but maximum user data throughput will be approximately half of this and the throughput is shared by all users of the same radio channel. The data rate decreases as the distance between the user and the radio access point increases.
Comments: In most offices, the data throughput will be greater than for 11b. Also, the greater number of radio channels (eight as opposed to three) gives better protection against possible interference from
neighboring access points. 802.11a-compliant products are available in North America, but there will not be a wide choice of vendors or lower prices until the second half of 2002. Conformance is shown by a
Wi-Fi5 mark from WECA.
When: Standard completed in 1999. Products are available now.


802.11b pil
Description: A physical layer standard for WLANs in the 2.4GHz radio band. It specifies three available radio channels. Maximum link rate of 11-Mbps per channel, but maximum user throughput will be
approximately half of this because the throughput is shared by all users of the same radio channel. The data rate decreases as the distance between the user and the radio access point increases.
Comments: Products are in volume production with a wide selection at competitive prices. Installations may suffer from speed restrictions in the future as the number of active users increase, and the limit of three radio channels may cause interference from neighboring access points.
When: Standard completed in 1999. A wide range of products has been available since 2001.


802.11d pil
Description: 802.11d is supplementary to the Media Access Control (MAC) layer in 802.11 to promote worldwide use of 802.11 WLANs. It will allow access points to communicate information on the permissible radio channels with acceptable power levels for user devices. The 802.11 standards cannot legally operate in some countries; the purpose of 11d is to add features and restrictions to allow WLANs to operate within the rules of these countries.
Comments: In countries where the physical layer radio requirements are different from those in North America, the use of WLANs is lagging behind. Equipment manufacturers do not want to produce a wide variety of country-specific products and users that travel do not want a bag full of country-specific WLAN PC cards. The outcome will be countryspecific firmware solutions.
When: Work is ongoing, but see 802.11h for a timeline on 5GHz WLANs in Europe.


802.11e pil
Description: Supplementary to the MAC layer to provide QOS support for LAN applications. It will apply to 802.11 physical standards a, b and g. The purpose is to provide classes of service with managed
levels of QOS for data, voice and video applications.
Comments: 11e should provide some useful features for differentiating data traffic streams. Many WLAN manufacturers have targeted QOS as a feature to differentiate their products, so there will be plenty of
proprietary offerings before 11e is complete. However, the successes or failures of these products will determine how eager manufacturers will be to adopt standard 11e features.
When: The finalized standard is expected in the second half of 2002. Products will be available in the second half of 2003 (0.6 probability).

802.11f pil
Description: This is a “recommended practice” document that aims to achieve radio access point interoperability within a multivendor WLAN network. The standard defines the registration of access points within a network and the interchange of information between access points when a user is handed over from one access point to another.
Comments: 802.11f will reduce vendor lock-in and allow multivendor infrastructures.
When: Completed standard expected in the second half of 2002. Products will be available in the first half of 2003 (0.7 probability).

802.11g pil
Description: A physical layer standard for WLANs in the 2.4GHz and 5GHz radio band. It specifies three available radio channels. The maximum link rate is 54-Mbps per channel — compared with 11 Mbps for 11b. 802.11g uses orthogonal frequency-division multiplexing (OFDM) modulation but, for backward compatibility with 11b, it also supports complementary code keying (CCK) modulation and, as an option for faster link rates, allows packet binary convolutional coding (PBCC) modulation.
Comments: Speeds similar to 11a and backward compatibility may appear attractive but there are modulation issues: Conflicting interests between key vendors have divided support within IEEE task group for the OFDM and PBCC modulation schemes. The task group compromised by including both types of modulation in the draft standard. With the addition of support for 11b’s CCK modulation, the end result is three modulation types. This is perhaps too little, too late and too complex compared with 11a. However, there are advantages for vendors looking to supply dual-mode 2.4GHz and 5GHz products, in that using OFDM for both modes will reduce silicon cost. If 802.11h fails to obtain pan-European approval by the second half of 2003, then 11g will become the high-speed WLAN of choice in Europe
(see “802.11g: A New Wireless Networking Standard," T-15-3353).
When: Completed standard expected in the second half of 2002. Products will be available in the first half of 2003 (0.7 probability).

802.11h pil
Description: This standard is supplementary to the MAC layer to comply with European regulations for 5GHz WLANs. European radio regulations for the 5GHz band require products to have transmission
power control (TPC) and dynamic frequency selection (DFS). TPC limits the transmitted power to the minimum needed to reach the furthest user. DFS selects the radio channel at the access point to minimize interference with other systems, particularly radar.
Comments: Completion of 11h will provide better acceptability within Europe for IEEE-compliant 5GHz WLAN products. A fast-dwindling group will continue to support the alternative HyperLAN standard
defined by ETSI. Although European countries such as the Netherlands and the United Kingdom are likely to allow the use of 5GHz LANs with TPC and DFS well before 11h is completed, pan-European approval of 11h is not expected until the second half of 2003, possibly longer.
When: The standard is expected to be finalized by the second half of 2002. Products will be available in the first half of 2003 (firmware implementation), with high availability in the second half of 2003 (0.7
probability).


802.11i pil
Description: Supplementary to the MAC layer to improve security . It will apply to 802.11 physical standards a, b and g. It provides an alternative to Wired Equivalent Privacy (WEP) with new encryption
methods and authentication procedures. IEEE 802.1x forms a key part of 802.11i.
Comments: Security is a major weakness of WLANs. Vendors have not improved matters by shipping products without setting default security features. In addition, the WEP algorithm weaknesses have been
exposed. The 11i specification is part of a set of security features that should address and overcome these issues by the end of 2002. Solutions will start with firmware upgrades using the Temporal Key
Integrity Protocol (TKIP), followed by new silicon with AES (an iterated block cipher) and TKIP backwards compatibility.
When: Finalization of the TKIP protocol standard is expected in the first half of 2002. Firmware will be available in the second half of 2002 (0.8 probability). New silicon with an AES cipher is expected by the
second half of 2003 (0.7 probability).


Bottom Line: Enterprises deploying Wi-Fi-certified WLAN products should be implementing additional security measures beyond those specified standards as they stood at the end of 2001. However, this is
a rapidly changing scene and enterprises need to monitor developments.
Gartner forecasts that there will be more than 10 million new WLAN PC users during 2002. Although most will be using the 802.11b physical layer standard, sales of 802.11a products will increase rapidly in
North America during the second half of 2002. Products complying with all the 802.11 standards, including a, b and g tri-standard modulation are expected to be available by the second half of 2003 (0.7 probability).

Gartner
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