WiFi has become a victim of its own success. Because it is ubiquitous and perceived as “free” uncapped data connectivity (compared to cellular data), it seems everyone and everything has come to rely on it for connectivity to applications of every type. There is a downside to that popularity: because so much is dependent on WiFi for connectivity, wireless networks and their access points within industrial, commercial, and healthcare facilities are increasingly stretched too thin as they struggle to support so many devices and users asking so much of the network. Ironically, the very things that make WiFi such a popular platform for consumer and enterprise connectivity are affecting its performance and usefulness to serve in such a critical role. New functionality called Multi-User, Multi-Input Multi-Output (MU-MIMO) in the latest release of the WiFi standard will enable product engineers to solve the congestion problems plaguing WiFi networks.
We’ve all experienced how WiFi networks are stretched thin at the local coffee shop, when too many users ask too much of the network and everything slows to a crawl. Everyone sips on lattes and tries not to get frustrated because the guy next to them is streaming video and ruining it for everyone, but it’s Exhibit A for how limited traditional WiFi is, and needs to evolve to meet greater demands. The same is true for enterprise WiFi networks, which are being used much more nowadays than just employees logging on to check email. WiFi networks have become indispensable as the wireless platform for a wide range of enterprise IT systems that utilize the 802.11 protocol to connect devices, share information, and stretch them too thin, which had major consequences for enterprise computing.
In 2015 alone, more than 563 million mobile devices and connections were added to wireless networks globally. Take, for example, hospitals where an increasing number of wirelessly-networked medical devices are bringing the vision for truly Connected Hospitals to life. That is a tremendous number of devices in a highly-compact and challenging RF environment all dependent on WiFi, and is just one example of how wirelessly-connected devices are pushing WiFi networks to the limit. If you look more broadly at Internet of Things (IoT) deployments, it is fair to conclude that the burden on WiFi networks is untenable if something doesn’t change.
The problem will only intensify in the coming years. IDC predicts that by 2020, IoT implementations will consist of more than 28 billion connected devices, a CAGR of 17.5 percent. Given that WiFi is often the connectivity protocol of choice for these implementations, that stratospheric growth in the number of connected devices will put a lot of pressure on WiFi networks creating widespread bottlenecks in the process—if not for an enhancement to the WiFi protocol that has significant implications for readers of ECN Magazine: the MU-MIMO capabilities in the recently-unveiled IEEE 802.11ac Wave 2.
Most discussions on the new 802.11ac Wave 2 protocol have focused on the topline speed increases that captured the headlines when the new standard was unveiled. I believe an equally important aspect of the standard, particularly for enterprise users, is a feature with the endearing acronym MU-MIMO that belies its importance for solving the stretched-too-thin problem I mentioned above. MU-MIMO enables WiFi networks to do four times as much work as before. MU-MIMO also goes by other names such as Next-Gen AC and AC Wave 2.
Last year, the new 802.11ac standard was unveiled in two stages. Wave 1 was a significant improvement over 802.11n in its own right, with advances like higher packet density, broader spectrum channels, and higher data rates. Wave 2’s inclusion of MU-MIMO capabilities and its 160 MHz wide channels are the critical elements for truly relieving the burdens on WiFi networks.
To understand its significance, it is important to compare it with the Single User Multiple Input/Multiple Output (SU-MIMO) capability that is part of the original WiFi standard. SU-MIMO sends data over a network to one device at a time. While SU-MIMO was a significant advancement at the time, bandwidth requirements have grown significantly in recent years and there are simply too many demands on the network today for the SU-MIMO architecture to be efficient. It is like asking a million people to form a single line, and then interact with them one-by-one. It will take forever, and it creates an enormous bottleneck in the process.
Historically, the technique IT administrators used to combat the influx of devices on a network was to install additional access points to help with load balancing and coverage. Hanging additional access points is neither efficient nor cost effective, but this Band-Aid fix creates its own set of RF challenges. In addition to the inefficiencies and increased costs, having too many access points condensed in an area increases RF contention, raises the noise floor, and makes client roaming very difficult. With the volume of traffic utilizing WiFi today, the underlying protocol needed a better approach, and the Wave 2 version of the 802.11ac protocol fills that need.
To achieve better throughput than its predecessor, 802.11ac leverages the 5 GHz band, operates in up to eight spatial streams (8×8) via MU-MIMO, offers increased bandwidth with channel sizes of 80 or 160 MHz, and employs transmit beamforming which sends signals directly to client devices. 802.11ac Wave 2 devices can support speeds up to 2.34 Gbps in the 5 GHz band, compared 802.11n’s max speed of 450 Mbps (assuming 3×3 MIMO). I should note that the 802.11ac is currently only unveiled in a form that allows MU-MIMO in the down-stream link (from access point to client), but as the technology evolves with 802.11ax, MU-MIMO will work in a bidirectional way for both up-link and down-link connections.
So what does all of this mean in terms of product design for ECN Readers? One of the key benefits of implementing Wave 2 is higher throughput for all MU-MIMO client devices because the transmission beamforming method that is fundamental to MU-MIMO creates a targeted data stream just for your client. This data stream does not have to be shared like it was in the past, which means higher throughput for your device. Since each device can now have its own dedicated data stream with higher throughput, each device can receive its own data and get off the network quicker than ever before. This results in less network congestion while also reducing the overall RF noise floor in the wireless network, which creates improved network efficiency, and a better experience for all WiFi devices on the network regardless of whether they use the newest standard or prior ones.
It is important to note that Wave 1 devices are interoperable with Wave 2, but don’t include the same features. It is also important to note that access points and devices both must support the new WiFi standard in order to take advantage of MU-MIMO, for example with embedded modules that utilize Wave 2. As long as both clients and the AP are MU-MIMO capable, then the AP can create data streams for each client that are truly simultaneous.
Another important consideration for product designers is how the new WiFi standard and Bluetooth complement one another. Given the ubiquity of both WiFi and Bluetooth connectivity, engineers should consider a WiFi + Bluetooth option in order to give users both types of connectivity. Many chipsets and modules are equipped with both WiFi and Bluetooth to provide seamless coexistence and performance. Be sure to choose from a module or device manufacturer that offers a solution equipped with the new Bluetooth 5 core specification in order to future-proof your design.
802.11ac Wave 2 is designed to solve the too-popular-for-its-own-good problems that are plaguing so many overburdened WiFi networks. The ability of MU-MIMO to dramatically increase the capacity and efficiency of WiFi networks is one of the most important allies that product designers now have to ensure the devices they are engineering will perform successfully without connectivity bottlenecks that stand in the way.