pointer

802.11 – 2012: Just Catching Up

The 802.11 protocol, or simply Wi-Fi as most users know it, is constantly under development. Users of 802.11 usually only notice the major changes, typically those that significantly increase overall Wi-Fi performance, like 802.11a or 802.11n, however device manufacturers, OEMs, and network engineers see all of the nuances of the protocol. With over twenty 802.11 specifications already ratified, and many more still in the development phase, it makes sense to occasionally “roll up” the changes into a single 802.11 specification. This is exactly what 802.11 – 2012 is all about.

802.11 – 2012 incorporates ten recently ratified 802.11 amendments into an overall 802.11 spec, making it much easier for engineers who are working with 802.11, especially those that may be new to Wi-Fi. Also, since many of the amendments include functional overlap, consolidation helps make potential design issues more obvious.

Here is a list of the ten specs that are part of the 802.11 – 2012 roll up, including the year of ratification and a brief description of each along with any network analysis implications.

802.11k: Radio Resource Measurement Enhancements (2008)
Mostly used by AP manufacturers, this amendment makes additional radio and network information available to WLAN devices. This information is used to make real-time decisions about WLAN management, typically for better load balancing.

It’s important for a WLAN network analyzer to recognize and decode this protocol amendment. One of the consequences of 802.11k is that very busy APs, for example an AP servicing a packed conference room, may not be able to adequately handle all of the traffic. This specification provides mechanisms for the AP or the controller to offload users to another AP, even if the new AP has a weaker signal strength than the impacted one. This could lead to signal strength issues for WLAN users, so it’s imperative to know whether or not a user has been offloaded using 802.11k.

802.11n: Higher Throughput Improvements Using MIMO (September 2009)
Enough said. If you’re not yet up to speed on 802.11n, you can check out this WildPackets info kit for some detailed information. Remember, WLAN network analysis solution should handle 802.11n, including the 3-stream capable devices that are currently being introduced into the market.

802.11p: WAVE—Wireless Access for the Vehicular Environment (July 2010)
802.11p deals with data exchange between high-speed vehicles, and between vehicles and a yet-to-exist roadside WLAN infrastructure based on licensed spectrum in the 5.85 – 5.925GHz band. Though the plans for this technology seem quite grandiose, activity in this area has been quite limited to date, and obviously has no affect on enterprise WLAN users. Any WLAN analysis capabilities for 802.11p are likely to be very specific to this particular application.

802.11r: Fast BSS Transition (2008)
This amendment is a good example of how various amendments interact, and sometimes even conflict with each other to degrade instead of enhance 802.11 performance. A critical aspect of Wi-Fi is mobility, and this typically involves a client device moving from AP to AP to maintain adequate signal strength as the user moves around. This movement creates a “transition” or a “hand-off” and it needs to take place relatively quickly for services to continue uninterrupted, especially time-sensitive services like VoIP over wireless (VoFi). As more and more amendments were added to 802.11 this transition time degraded significantly, causing problems for services like VoFi. This amendment addresses this degradation, making transitions as fast as they can be.

Given the sensitivity of time-sensitive protocols, WLAN analyzers must be capable of decoding and analyzing the packets involved in a BSS transition, and this of course includes 802.11r. Expanding on this concept, a good WLAN network analyzer will also manage and report on all transitions, keeping statistics on how both APs and clients are performing by measuring all transition times.

802.11s: Mesh Networking, Extended Service Set (July 11)
Mesh networking specifies an architecture and protocol for WLANs that use radio-aware metrics over self-configuring multi-hop topologies. Essentially, 802.11s enables the creation of high-performing, scalable, ad-hoc networks, often with no wired network access at all. One of the most widely discussed use cases is in emergency services, like those provided by the Federal Emergency Management Agency, where a scalable network needs to be set up very quickly in a remote area for a finite period of time.

It is highly unlikely that enterprise customers will take advantage of mesh technology. WLAN analysis of mesh environments is likely to be highly specialized and mostly transient, so there’s no need for the typical enterprise-focused WLAN analysis system to deal with 802.11s, at least not anytime soon.

802.11u: Interworking with Non-802 Networks (February 2011)
This is an extremely hot topic in mobile computing, and one that will continue to get tremendous attention. It also requires solutions to some pretty difficult problems, including discovery, authentication, authorization, and compatibility, hence progress towards implementation has been slower than anticipated.

Although not many products are taking advantage of this technology yet, both the need and the desire for products to seamlessly transition from other networks to 802.11, and back, is very apparent and it is just a matter of time. WLAN network analysis solutions should be capable of analyzing the 802.11u protocol enhancements today.

802.11v: Wireless Network Management (February 2011)
802.11v provides a mechanism for wireless clients to share information about the WLAN environment with each other and APs to improve WLAN network performance in real time.

Most client devices do not yet take advantage of this new capability, but as compatible devices (both client and infrastructure) come to market the need to analyze 802.11v packets will become very important, especially in determining if the information shared is really resulting in anticipated improvements.

802.11w: Protected Management Frames (September 2009)
802.11w specifies methods to increase the security of 802.11 management frames. Management frames are 802.11 packets that control communication on the WLAN, but do not contain data. Examples include beacons, RTS/CTS, probe responses, acknowledgements, etc. Currently management frames are sent “in the clear” making them potentially vulnerable to malicious manipulation.

Analyzing management packets is a very significant part of overall WLAN network analysis, so the ability of a WLAN network analyzer to analyze “protected” management frames is critical.

802.11y: 3650–3700 MHz Operation in the U.S. (2008)
802.11y specifies a “light-licensing” scheme for U.S. users to take advantage of spectrum in the 3650 – 3700 MHz band, at power levels that are significantly higher than those used in the 2.4 or 5GHz bands. The use case for this technology will typically be for longer distance, point-to-point, backhaul communication using 802.11.

The average customer is not likely to ever come across this technology, and with the exception of specialized uses even most enterprise customers will never need to worry about 802.11y. If your WLAN analysis solution can’t handle 802.11y it’s not likely to matter.

802.11z: Extensions to Direct Link Setup (September 2010)
Direct link setup (DLS) allows WLAN client devices to connect directly to each other, bypassing the typical link through an infrastructure AP. This has many benefits, including an increase in speed (between the clients), an increase in network throughput (for all users), and an increase in overall service delivery, especially for multimedia (like a computer to DVR connection or a laptop to projector connection).

The Wi-Fi Alliance (WFA) already has a program in place called Wi-Fi Direct™ that addresses this functionality, and most commercial devices certified under this program. At a minimum your WLAN analysis system should be capable of analyzing Wi-Fi Direct.

The recently ratified 802.11 – 2012 specification is most certainly a wide-ranging roll-up. From generic and already prolific technology like 802.11n to highly specific technology like 802.11y, this new specification integrates all current Wi-Fi technology into a single specification again, making it easier for developers and testers to find all the information they need in a single document. And although the ratification of such a specification may seem trivial to end users of this technology, they will also benefit, both from tighter feature integration as well as faster time to market for interoperable 802.11 devices.

One thought on “802.11 – 2012: Just Catching Up

Leave a Reply