Delivering Breakthrough Performance with 802.11ac
Breaking the wireless Ethernet gigabit barrier
By: Joe Zeto
Jul. 18, 2012 01:51 PM
Consumers are continuing to adopt multiple connected devices and video content is expected to reach more than 70 percent of global traffic. This growth and the increased reliance on wireless networks is putting stress on existing 802.11a/b/g/n networks. As a result of this high usage, users are likely to experience deteriorated performance, choppy videos and slower load times. At a time when IT managers report that network users are now averaging more than one Wi-Fi connected device per person, solutions to handle the rapid growth of devices are at a premium.
The next generation of the 802.11 standard, or IEEE 802.11ac, promises to finally break the wireless Ethernet gigabit barrier. This technology will deliver higher bandwidth while retaining better quality of experience (QoE) for end users, and is expected to be adopted rapidly into all markets: residential, enterprise, carrier and large venue.
Some of the first applications for 802.11ac's faster speeds will better residential video streaming, data syncing between mobile devices, and data backup. Streaming digital media between devices faster and simultaneously connecting more wireless devices will be some of the starting benefits for consumers and enterprises. In terms of service providers, they will be able to deploy the new technology to offload traffic from congested 3G and 4G-LTE cellular networks, and in dense operator hotspots 802.11ac will supply better performance to more users.
To date, all 802.11 revisions have focused on increasing transport speeds, which lead to higher traffic delivery rates and ultimately to faster response times as experienced by the end user. The introduction of 802.11n brought advances of MIMO (multiple-in, multiple-out) to deliver traffic over multiple spatial streams, and packet aggregation. MIMO delivered marked improvements in physical transport rates, enabling more bits per second to be transmitted than ever before over Wi-Fi. Packet aggregation delivered equally impressive improvements in transport experience, allowing devices to send more data once they had gained access to the wireless media. The new 802.11ac protocol is continuing down this path by preserving aggregation techniques, advancing the physical transport rates yet again, and introducing the concept of parallel transport into Wi-Fi through a technique known as Multi-User MIMO (MU-MIMO), where multiple client devices are receiving packets concurrently.
This is the first time Wi-Fi history that directed traffic can be delivered to multiple client devices at the same time. This ability has significant impact on delivery of content to any location with multiple users, especially where content is revenue-generating or critical.
Achieving Increased Gigabit+ Performance with 802.11ac
Overcoming Technical Challenges
IEEE 802.11ac makes this problem significantly more challenging. In addition to being deployed into an existing environment with ten years' worth of previous releases, 802.11ac makes use of advanced technologies that are substantially more complex and demanding than previous versions. This latest generation of 802.11 requires a rethinking of how the technology is developed and tested to include a much more holistic view through the product development life cycle.
Traditionally, the RF section is verified using one set of equipment, and then the upper layer functions are tested using a second set of tools. The overall technical complexity and the introduction of new technologies such as TxBF demand coordination and control between the different layers of the protocol stack. Without this coordination, it would be difficult to utilize these functions and to quickly pinpoint performance issues.
802.11ac brings the promise of moving Wi-Fi into the limelight as a trusted and capable communication protocol, and will require equipment and rigor to match. The new generation of testing should be able to decode every frame in real-time and determine each frame's RF characteristics, as well as their frame-level performance, and generate every frame without limitation in real-time to adequately test receiver performance. Previous approaches use a digitized data record approach for both generation and analysis, creating or capturing what are known as I/Q files, and equipment typically adapted from the general-purpose RF domain. This result in equipment being capable of a single spatial stream, and able to generate or capture a small fraction of the frames required to perform testing. To meet the need, the approach needs to be able to generate and analyze all frames in real-time to the limit of the specification, tightly integrate RF and MAC functionality in 802.11ac, and include integral, real-time channel emulation to address TxBF performance.
Increasing Performance for All Markets
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