By: Tom Williams, Editor-in-Chief
With increasing user demand and a rich set of certification programs, Wi-Fi is poised to become a nearly universal medium for wireless digital connectivity.
It may already seem like it is everywhere—in just about every home with more than one computer, in airports, coffee shops and offices—but the most popular form of wireless digital connectivity is aiming to become even more widespread and more available in vast numbers of devices, both industrial and consumer. Wi-Fi, now supported since 1999 by the Wi-Fi Alliance, a growing consortium of over 400 companies, has long had a product certification program that ensures that certified devices work together and has since 2000 certified some 10,000 different devices. Annual shipments are predicted to reach one billion units this year and to top two billion by 2015.
These have primarily been PC and networking devices along with handsets and consumer electronics. Now, the Wi-Fi Alliance is launching new programs and specifications to extend the reach of the wireless network technology even further and will inevitably encompass a wide range of connected embedded devices. It has long been a truism that technologies that become popular and widespread and achieve performance at low cost in the PC arena inevitably migrate into the embedded world. It is no different with Wi-Fi.
The first of these initiatives is the Wi-Fi Certified Hotspot program. Hotspots are Wi-Fi access points managed by hotspot providers in such places as hotels, airports, coffee shops that can be offered for free in connection with some other service or for a connection fee according to the policy of the provider. Today there are over 750,000 such hotspots but these are predicted to number in the millions in just a couple of years. There are a number of reasons such as the just plain popularity of Wi-Fi, but there is also a genuine need to offload the cellular networks.
Over the next two years, data traffic on mobile networks it expected to grow to four times the volume of voice traffic, approaching five million terabytes in a year. According to Wi-Fi Alliance Technical Director, Greg Ennis, “Wi-Fi will always be faster than 3G or 4G, but when people are mobile and can’t use Wi-Fi, they use the cellular network.” The build-out of Wi-Fi is expected to make it more available to the mobile data user and, of course, we can also expect voice-over-Wi-Fi as well, using VoIP technology.
The Wi-Fi certification program is intended to make it much easier for users to get connected at service provider Wi-Fi hotspots by providing automatic provisioning, authentication and network selection. There will also be provisions for easier and more automatic roaming agreements among service providers. The certification program will cover the various types of devices as well as the hotspots themselves. Thus a subscriber to one service provider could automatically connect through the hotspot provided by another and the billing information would be automatically transferred.
Key elements of the Certified Hotspot program would include automated network discovery and selection. Thus a device contacting a hotspot would automatically select an available network based on subscriber information, operator policies or network optimization. Automated access would be granted based on credentials, SIM cards or other subscriber information, which would also be used under the terms of roaming agreements. In the rarer cases where a new account needed to be established, this would also be made as smooth as possible using a common methodology across vendors. Finally, all over-the-air transmissions will be encrypted using WPA2 technology (Figure 1).
Wi-Fi Direct—Up Close and Personal
Greg Ennis remarks, “People tend to think of Wi-Fi as wireless Internet, but that’s only one use of Wi-Fi.” The next step appears to be to move into the peer-to-peer personal area networking realm that has until now been the province of Bluetooth. There was also a now abandoned attempt to set up a wireless USB technology. Bluetooth does not have sufficient range and compatibility to cover all the applications that its proponents had once envisioned for it. Now Wi-Fi Direct will be able to directly connect devices without a Wi-Fi network or hotspot available.
Wi-Fi Direct will have three modes: a one-to-one configuration, a one-to-many configuration and a concurrent Wi-Fi AP and peer-to-peer configuration (Figure 2). The one-to-one arrangement is expected to be a very common mode. Devices will be able to connect directly to one another to share content or applications. This will allow such things as printing directly from a camera, sharing video games, displaying pictures from a phone on a TV, etc. The possible applications in the embedded world are many as well, such as configuring devices or gathering data from devices with a handheld unit or even a smartphone. The potential for the configuration of machine-to-machine autonomous and semi-autonomous systems is also looking very attractive.
The one-to-many configuration allows users to quickly connect peripherals such as a camera, speakers or printers to a PC or to quickly set up an ad hoc network of computers to do things like share images or a presentation with a group without the need for a projector or a screen. It will be possible to connect some, but not all, legacy devices in such a scheme. Wi-Fi Direct Connect-certified devices will be able to connect to multiple other devices.
The third configuration allows some devices, such as PCs, to link directly to a group of Wi-Fi Direct Connect-certified devices and also share a network connection with the group via a hotspot. In this scenario, two different security domains exist—one for the group and one for the WLAN. Wi-Fi Direct Connect has management features built in so that an IT manager or a hotspot provider can disable this kind of cross-connection. This would be used by a hotspot provider, for example, who does not want multiple devices sharing a connection on a hotspot that wants to charge for each connected device. In addition, not all Wi-Fi Direct devices will be able to support this simultaneous WLAN connection.
The setup of a Wi-Fi Direct connection or connections is not automatic; it requires active agreement, so it supports the security of letting a user directly identify who is being given access. One device must specifically request access and the other device must specifically grant permission. The Wi-Fi Protected Setup specifies the process that consists of a user pushing a button (or pressing or clicking a virtual button on a screen), which causes a window to pop up on the other device. Once the request is acknowledged, a secure connection is established using WPA2 security protocols. Over-the-air transmissions are encrypted with government-grade Advanced Encryption Standard (AES) technology.
According to the Wi-Fi Alliance’s Ennis, “The one-to-one configuration may be the predominate one. It supersedes Wireless USB and much of what Bluetooth wishes it could do. Doing peer-to-peer applications at Wi-Fi speed can support video and at Wi-Fi ranges.”
And it doesn’t look like Wi-Fi is stopping here. There are at least two other initiatives on the horizon. One is to move Wi-Fi into the 60 GHz range, which will allow it to deliver multi-gigabit data rates (up to 7 Gbit/s), albeit at a shorter range than traditional Wi-Fi. This effort corresponds to work being done in IEEE 802.11ab and now apparently in cooperation with the WiGig Alliance. In addition, there is a move to define Wi-Fi operation in the 5 GHz band, which could deliver a gigabit data rate. This corresponds to work being done on IEEE 802.11ac, which aims at providing a multi-station throughput of at least 1 Gbit/s and a single link throughput of at least 500 Mbit/s.
Wi-Fi is also moving into the healthcare arena, and the Alliance is working closely with the medical Continua Alliance that seeks to establish standards for communicating medical devices. The concurrent emergence of the Smart Grid and the Smart Home has recently led to the Association of Home Appliance Manufacturers (AHAM) specifying Wi-Fi as a top rated technology along with ZigBee and HomePlug Green PHY. In addition, what the FCC has called “Super Wi-Fi” is looking to move into the television white spaces that have been opened up since the specification of digital transmission. These are attractive for outdoor networking and the use of Wi-Fi in extended areas such as neighborhoods or college campuses.
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