Setting the Foundations for 802.11ac and 802.11ad

IEEE 802.11 is a set of standards for implementing wireless local area network (WLAN) computer communications in the 2.4 and 5 GHz frequency bands. These standards are created and maintained by the IEEE LAN/MAN Standards Committee. The original version of these standards was released in 1997. However, the origins of 802.11 stem from a 1985 ruling by the U.S. Federal Communication Commission that released the ISM (Industrial, Scientific and Medical) ban for unlicensed use to allow civil use of spread spectrum technology.

IEEE 802.11 currently includes 21 ratified standards, and each new standard usually improves the security, the throughput and/or the interconnectivity between wireless network devices – leading to current capabilities like streaming NetFlix videos and real-time audio  on wireless home networks and providing reliable access to mission-critical applications at work. And the industry is not resting at 21. Several new standards, most notably 802.11ac and 802.11ad, promise to provide even greater throughput, continuing to drive the dominance of 802.11 as the go-to wireless technology. We will discuss these protocols in more detail in subsequent blogs, but before we dive into these new standards, let’s look at the current state of 802.11 wireless.

Most enterprise and home wireless networking uses 802.11b, 802.11g or 802.11n. 802.11b and 802.11g have been around for a long time now but are still very widely used. 802.11a which was also introduced some time back to take advantage of the open spectrum in the 5GHz band was never met with wide acceptance, though it is certainly in use and has some distinct advantages, including more overall available bandwidth and less interference, from both other WLAN networks and non-802.11 devices.

802.11n is one of the newest standards and it offers a major upgrade from its predecessors, increasing the maximum net data rate from 54Mbps to 600Mbps. Advanced technology is required to achieve this ten-fold increase in data rate, and although the 802.11n standard has been ratified for a few years now, manufacturers are still not taking advantage of the full specification.

Although a ten-fold increase in data rate sounds great in theory, there are a number of practical issues that arise regarding physical implementations that make achieving the full potential of 802.11n quite difficult.  802.11n takes advantage of two significant technologies to achieve these data rate improvements – channel bonding and MIMO (multiple input, multiple output). Channel bonding leverages existing technology and is therefore relatively easy to implement, but does have potentially serious impacts on existing 802.11b and 802.11g networks, so its use must be carefully planned. MIMO, on the other hand, is a radical shift in 802.11 data transmission.  In 802.11a/b/g, most devices have two antennae and one data stream, or bit stream. This bit stream is sent through both transmit antennae and received by both receiving antennae. 802.11n allows for multiple inputs and multiple outputs (MIMO), providing each transmit and receiving antenna with its own unique bit stream, and up to four bit streams can be sent simultaneously, thus increasing the throughput of your data fourfold. Perfect, right?

Theoretically, yes. But designing and manufacturing devices that can implement this technology, while still meeting other computing standards, like power consumption and physical form factors, can be challenging. And the biggest issue is with power consumption. Sending a different bit stream over each antenna requires significantly more power than sending the same bit stream. This is not so much of an issue for devices designed to be plugged in 24×7, like APs, but for clients, especially mobile clients like laptops and smart phones, the additional power requirements make full realization of the specification (4 distinct bit streams @ 600Mbps) nearly impossible, at least given current battery technology. That’s why you see very few 802.11n client devices that exceed 300Mbps in the market today.

In addition to IEEE sponsored specifications, industry associations are also very active in 802.11 technology, with the Wi-Fi Alliance (WFA) being the most well known. The WFA recently sponsored what is becoming a very popular 802.11 operating mode called Wi-Fi Direct. Loosely based on the 802.11ad-hoc mode, which was very insecure and therefore mostly disabled by users, Wi-Fi direct is a software protocol that allows devices certified under Wi-Fi Direct to exchange data without an Internet connection or a wireless router, in a highly secure and controlled manner. It provides a similar service to end users as Bluetooth, but it’s faster and allows devices to be farther apart when communicating, even supporting bandwidth intensive applications like video streaming.

So that’s where things are today. As we mentioned at the beginning, there’s much more to come, especially with the introduction of 802.11ac and 802.11ad in the near future, which will serve to further entrench 802.11, not only as a standard, but as an overall platform for development of unique capabilities. Join us next week as we dive deeper into the details of 802.11ac and 802.11ad, and their potential use cases.

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