February 27, 2012 – Initial steps toward commercialization of the next-generation Wi-Fi platform known as 802.11ac bode well for network service providers who are building their wireless strategies on Wi-Fi technology.
The yet to be finalized standard, also known as Wi-Fi 5G, got a strong boost from Broadcom in early January with that chipmaker’s launch of the world’s first 802.11ac system-on-chip (SoC). Chipmaker Qualcomm Atheros followed in February, setting the stage for introduction of initial consumer products in the second half of the year, some of which were shown in prototype form at CES in January.
According to the IEEE, at minimum, for any given link distance, users can expect throughput on 802.11ac to be three times that of 802.11n. “This is a big launch for us,” says Michael Hurlston, senior vice president of Broadcom’s wireless connectivity group. “5G Wi-Fi offers tremendous advantages in reliability, range and throughput.”
Just how service providers will go about incorporating the 5G benefits into their Wi-Fi infrastructures remains to be seen. Leading providers of the carrier-class systems that network operators are putting into the field to support metro-area coverage for fixed and mobile connectivity have yet to signal their plans for 802.11ac, but sources say discussions with customers as to how to make use of the new platform are part of the strategic roadmap taking shape around cable MSOs’ ambitious plans for use of Wi-Fi (see December issue, p. 1)
While it remains to be seen how the multiple new features available for 802.11ac will be implemented on consumer devices, home routers and outside plant, industry observers are predicting the pace of adoption will outstrip that of 802.11n, which was introduced in 2007 and today is ubiquitously deployed on smartphones, tablets, connected TVs, game consoles and Blu-ray players as well as computers. ABI Research, for example, projects that, starting from a small volume base this year, the pace of shipments will accelerate to where 802.11ac will be the dominant Wi-Fi protocol by 2014.
“With the exception of a small and dwindling number of 802.11g chipsets, everything has already shifted to 802.11n, and it has happened faster than most people expected,” says Philip Solis, research director for mobile networks at ABI. “This is a clear indication of what will happen with 802.11ac.
“The 1×1 version of 802.11n replaced 802.11g,” he notes, in reference to the single antenna version of the standard. “A rapid transition will occur with 802.11ac, but without the messy politics that slowed down the standardization of 802.11n in the past.”
In-Stat , too, predicts rapid uptake for 802.11ac, with shipments of 5G devices totaling nearly one billion by 2015. By that time 100 percent of shipments for hot spot access points will be 802.11ac enabled, the researcher says.
ABI and others say that most devices will use chipsets that operate in both the 5 GHz band, the sole band used by 802.11ac, and the 2.4 GHz band, the band commonly used by 802.11n devices, although that standard also supports use of the 5 GHz band. Indeed, the chipset announcements so far validate this assumption, which has important implications for driving use of the 5 GHz band on legacy 802.11n access points as well as 802.11ac APs.
Broadcom touts its BCM43460 chipset as a platform suited for carrier-class access as well as enterprise Wireless LAN applications. “We’re sampling with a bunch of customers,” Hurlston says, “Six to eight months from now you’ll be able to go into Best Buy, Staples, Office Max and other retail outlets and buy a router or PC product based on 5G Wi-Fi.”
Expectations for such a rapid rollout ahead of the anticipated formal approval of the standard next year rest on the fact that the proliferation of Wi-Fi devices is choking performance on 802.11n. “Phones, tablets, portable games, smart TVs, connected Blu-ray players – they’re all tapping into the wireless network,” Hurlston says. Wi-Fi bandwidth exhaust has also become a big problem in enterprise networks, he adds.
According to a recent enterprise survey conducted by analyst firm Infonetics, employees all over the world are offloading routine tasks from desktops and laptops to smartphones and tablets, and IT departments are scrambling to connect those devices. As the number of mobile devices and the deployment of cloud based enterprise networks continues to scale at a dramatic rate, IT managers must reconsider how they provision, secure and control enterprise computing resources and information access, Hurlston notes.
Further fueling the demand for higher capacity Wi-Fi is the surge in mobile carrier plans to deploy “small-cell” technology as a means of efficiently utilizing hot spots to relieve bandwidth strands on 3G and 4G cell systems. As reported elsewhere, industry preparations for tight integration between mobile and Wi-Fi in the outside plant have accelerated with completion of standard approaches to security, authentication and automatic handoff between networks.
802.11ac is a complicated standard that employs a variety of new techniques and ways to bond and utilize channels, some as part of the mandatory baseline and some as options. While the chipsets for access points like Broadcom’s put into play many of the more advanced features, most observers anticipate end user devices will stick to the baseline, with the exception of some enterprise components that might go for the more advanced features.
Perhaps the biggest advantage over 802.11n is the fact that 802.11ac operates exclusively in the 5 GHz band with access to 495 MHz of relatively unused unlicensed spectrum, compared to the 83.5 MHz of unlicensed spectrum available to 802.11n in the crowded 2.4 GHz tier. While 802.11n access points by definition are designed to operate in the unlicensed regions of 2.4 and 5 GHz, the vast majority of 802.11n-equipped end user devices only have 2.4 GHz antennas.
The greater amount of bandwidth at 5 GHz allows for bonding of multiple 20 MHz channels into 80 MHz or 160 MHz pipes, which vastly expands the throughput. In 802.11n, bonding is limited to two 20 MHz channels. Moreover, 802.11ac supports modulation all the way to 256 QAM (quadrature amplitude modulation) versus a 64 QAM ceiling for 802.11n, although how often the more bandwidth efficient 256 QAM will come into play will depend on AP design features, link distances and other conditions.
Taking its full potential into account, claims for 802.11ac can be eye popping. At short distances with utilization of the eight-channel bonding at 160 MHz and with the most advanced features in play with eight antennas at the transmit and receive ends, connections operating at up to 3.47 gigabits-per-second over very short distances are possible. But these are not the numbers to go by with respect to real-world expectations, any more than the maximum 600 mbps rate has been for 802.11n.
Instead, when it comes to the simplest implementation of 802.11ac in devices and the one anticipated for smartphones and other baseline consumer products, which is to say, a single-antenna, 80-MHz channel connection, the IEEE says the 802.11ac data speed at a distance of 30 feet or so would be 433 mbps. But these are game-changing data rates for home usage.
Even with the lower indoor rates sustained with the falloff over greater distances throughout the home, the simple device throughput will be high enough to support wireless transmission of HD-level over-the-top programming and other media from 802.11ac routers to TVs, Blu-ray players and other connected devices. “IEEE 802.11ac is expected to herald the arrival of living room video products that will make enjoying streaming Web video as easy as watching cable TV is today,” the IEEE says in an overview of the new protocol.
From the perspective of what network service providers might expect for on-the-go connectivity across Wi-Fi metro deployments, the Broadcom SoC provides some clues. Leading providers of carrier-class Wi-Fi infrastructure have already begun to introduce small-cell technology using standard approaches to seamless integration of the user experience across fixed and mobile networks. While these suppliers haven’t signaled their intentions with 802.11ac, service providers can expect significant throughput and coverage gains if and when vendors incorporate 802.11ac into their infrastructures.
Broadcom says its 802.11ac SoC is three times faster and six times more power efficient than its 802.11n solutions and, with support for 802.11n at 2.4 and 5 GHz, the chipset is backward compatible with those platforms. Used with 3 x 3 antenna arrays, the SoC can deliver data at up to 1.3 gbps at short distances, the company says.
One of the great advances in wireless communications, introduced with 802.11n and now greatly enhanced with 802.11ac, is Multiple-Input, Multiple Output (MIMO) technology, which provides more robust coverage and greater bandwidth efficiency through various techniques that use multiple antenna arrays in transmitters and receivers to support spatial separation of bit segments in the communication stream.
One of these techniques, known as beamforming, allows the transmitter to weight phase and gain in favor of transmitter-to-receiver antenna paths that generate the highest possible signal power at the receive end. Another is spatial multiplexing, which divides the bit stream across multiple antenna paths within the same frequency so that the aggregate bit rate is much higher that would be possible using single antennas.
MIMO applications are optional in both 802.11n, which supports a maximum of four-antenna arrays, and 802.11ac, which supports up to eight. 802.11ac introduces Multiple-User MIMO (MU-MIMO) as well, which uses precoding to identify multiple receiving devices for a transmission so that spatial division multiplexing can be used to enable more than one device to simultaneously receive a bit stream delivered over a given frequency channel.
Theoretically, for example, all the 802.11ac-connected TVs in the home could simultaneously receive an OTT HD program within the same bandwidth allocation. But here, again, the expectation is that, early on, consumer devices won’t use multiple antenna arrays, which will deny users the beamforming and spatial multiplexing advantages of MU-MIMO.
Some skeptics believe many of the advanced features associated with 802.11ac will not gain traction even over the long haul, but, judging from the pace of advances in 802.11n equipment, especially for carrier-class applications, betting against full featuring of 802.11ac could be a strategic mistake.