Tag Archive for Beamforming

| October 17, 2013
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A Close Look at 802.11ac Wi-Fi

TA Close Look at 802.11ac Wi-Fiech pundits argue that the new Wi-Fi standard 802.11ac will replace wired gigabit Ethernet networking. 802.11ac is a supercharged version of 802.11n, offering link speeds ranging from 433 Mbps, up to multiple gigabits per second.

Wi-FiTo make 802.11ac dozens of times faster than 802.11n, the new standard works exclusively in the 5GHz band uses a huge chunk of bandwidth (80 or 160MHz), operates in up to eight spatial streams (MIMO), and a technology called beamforming.

At its core, 802.11ac is essentially an updated version of 802.11n, according to Sebastian Anthony the author of an ExtremeTech article “What is 802.11ac WiFi, and how much faster than 802.11n is it?” 802.11n was a huge performance increase over 802.11a and g. 802.11n introduced some key technologies that brought massive speed boosts. Where 802.11n had support for four spatial streams (4×4 MIMO) and a channel width of 40MHz, 802.11ac can use eight spatial streams and has channels up to 80MHz wide, which can be combined to make 160MHz channels. This means that 802.11ac has 8 x 160MHz of spectral bandwidth to play with, versus 4 x 40MHz – a huge difference that allows 802.11ac to send vast amounts of data across the airwaves.

Beamforming

What is new in Wi-Fi

802.11ac also introduces 256-QAM modulation (up from 64-QAM in 802.11n), which sends 256 different signals over the same frequency by shifting each signal to a slightly different phase. In theory, this quadruples the spectral efficiency of 802.11ac over 802.11n. Spectral efficiency is a measure of how well a given wireless protocol/modulation/multiplexing technique uses the bandwidth available to it.

802.11ac also introduces standardized beamforming Matthew Gast, Director of Product Management at AeroHive Networks published an article, “Investing in Beamforming: Is it worth it?” that explains beamforming.

Aerohive logoRather than transmitting a radio signal in all directions, beamforming figures out where the receiver is, and focus the energy towards the receiver. Instead of spraying radio energy all over the place, send packets as a “rifle shot” directly to the receiver’s antenna Mr.Gast explains.

Beamforming is a two-step process: First, figure out how to “aim” the transmission at the receiver, and second, send the transmission. With beamforming, a transmitter is betting that by paying the cost of the channel measurement process, the data transmission that follows will speed up enough to pay off the cost.

802.11n Beamforming was non-standardized, in 802.11ac, there is only one method of beamforming, called the Null Data Packet (NDP). (rb- Read the AeroHive article for a full description of NDP)

Aerohive’s Gast concludes that by steering the energy towards a receiver, beamforming enables you to take a step up to a higher data rate. Mr. Gast estimates that 802.11-based beamforming gives you a 3-5 dB gain.

802.11ac is speedyIn theory, at the 5GHz band with beamforming, 802.11ac should have the same or better range than 802.11n  However, Mr. Anthony says the 5GHz band, has less penetration power so it doesn’t have the same range as 2.4GHz (802.11b/g). The ExtremeTech article concludes that’s an acceptable trade-off: there simply isn’t enough spectral bandwidth in the cluttered 2.4GHz band to allow for 802.11ac’s gigabit-level speeds.

ExtremeTech‘s Anthony calculates there are two answers to how fast is Wi-Fi 802.11ac, the theoretical max speed, and the practical max speed that mere mortals will get surrounded by lots of signal-attenuating obstacles.

He calculates the theoretical max speed of 802.11ac is eight 160MHz 256-QAM channels, each of which is capable of 866.7Mbps – a grand total of 6,933Mbps, or just shy of 7Gbps. That’s a transfer rate of 900 megabytes per second. Compare this with 802.11n’s max theoretical speed, which was 600Mbps. He then says in practice, the current max speed of 802.11ac devices is 1.7Gbps.

ExtremeTech points out there will be a second wave of 802.11ac devices – due in 2014 after the standard is finalized – before 160MHz channels and multi-gigabit speeds become a reality. The max speed over an 80MHz channel is 433.3Mbps, and there aren’t any 802.11ac chipsets that support up to eight streams.

Broadcom logoKevin Fitchard at GigaOM reports that recently the Wi-Fi Alliance kicked off its 802.11ac certification program. First to get the official Wi-Fi stamp of approval was the Samsung Mega 6.3, followed by two other Samsung models.

As with the 802.11n certification process, the Wi-Fi equipment makers are moving faster than the standards bodies. The IEEE is actually still putting the finishing touches on the 802.11ac standard, which is not due until 2014.

Wi-Fi certifiedThe Wi-Fi Alliance expects the first batch of ac devices will support speeds of 433 Mbps and progress into more advanced levels of the standard. The Alliance has pre-certified systems from companies like Broadcom (BRCM), Qualcomm (QCOM), Realtek, and Marvell (MRVL). Cisco (CSCO) was one of the first vendors to get an access point certified.

“AC is going into mobile and portable devices first…,” Wi-Fi Alliance Marketing and Program Management Director Kelly Davis-Felner said. ABI Research estimates that 40 percent of all ac devices shipped in 2013 will be handsets.

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Wi-Fi will replace wired Ethernet networkingWhile tech pundits argue that the new 802.11ac Wi-Fi will replace wired gigabit Ethernet networking at home and in the office. While the consumerization of IT and BYOD are strong forces, the life-cycle of cabling infrastructure is 25 years, a cost not lightly abandoned in the walls. it is more likely to happen at home first. Who wants all the crappy wires running all over the house?

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Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.

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| February 7, 2012
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Data Centers To Go Wireless

Data Centers To Go Wireless

MIT’s Technology Review reports researchers from IBM (IBM), Intel (INTC), and the University of California, Santa Barbara have come up with a way to improve data transmission in data centers. Heather Zheng, associate professor of computer science at UCSB who led the research says wireless is the answer to the in-rack cabling mess usually found in data centers. In their paper (PDF), the researchers say that transmitting data wirelessly within a data center would be simpler than rewiring data for tech titans like Google (GOOG), Facebook, or Twitter.

Line-of-sight connections

WiFi radio wavesThe earlier challenge for multi-gigabit wireless in the data center was it required a line-of-sight connection to be useful. Achieving the required data center speed could not happen in the maze of metal racks, HVAC ducts, and electrical conduits that make up most data centers.

TR reports that the researcher’s solution is to bounce 60-gigahertz Wi-Fi signals off the ceiling, which could boost data transmission speeds by 30 percent. Stacey Higginbotham at GigaOm points out that this could result in data transfers up to 500 Gigabits per second. She says current Ethernet cables in data centers are generally 1, 10, or maybe 40 gigabits per second.

60-gigahertz Wi-Fi for servers

Data center ceiling WiFiMs. Zheng and colleagues used 60-gigahertz Wi-Fi, which has a bandwidth in the gigabits-per-second range and was developed for high-definition wireless communications according to TR. However, it has its limitations, says Ms. Zheng. To maximize the bandwidth and reduce interference between signals, it needs to use 3D beamforming to focus the beams in a direct line of sight between endpoints. “Any obstacle larger than 2.5 millimeters can block the signal,” she says in the TR article.

One way to prevent the antennas from blocking each other would be to allow them to communicate only with their immediate neighbors, creating a type of mesh network. But that would further complicate efforts to route the data to the proper destinations, Professor Zheng told TR. Bouncing the beams off the ceiling directly to their targets not only ensures direct point-to-point communication between antennas but also reduces the chances that any two beams will cross and cause interference. “That’s very important when you have a high density of signals,” she says.

Flat metal plates placed on the ceiling offer near-perfect reflection. “You also need an absorber material on the rack to make sure the signal doesn’t bounce back up,” says Ms. Zheng.

Wireless can add 0.5 terabytes per second

Data centerAccording to Technology Review, the UCSB team worked with Lei Yang from Intel Labs in Oregon and Weile Zhang at Jiao Tong University in Xi’an, China, to simulate a 160-rack data center to see how the system might work. “Our simulation shows that wireless can add 0.5 terabytes per second,” she says.

IBM is also looking into using wireless technology in data centers, Scott Reynolds, a researcher at IBM’s T.J. Watson Research Center in Yorktown Heights, NY, who has been developing 60-gigahertz systems told TR. “These data centers are just choked with cables,” he says. “And so every time you want to reconfigure one it’s very labor-intensive and expensive.” But one problem with turning to wireless transmission, he adds, is that “you need to have hundreds of these wireless data links operating in a data center to be useful.” Since 60-gigahertz Wi-Fi has only four data channels, it’s important to configure the beams so they don’t interfere with each other.

Mark Thiele, the EVP of data center technology at Switch Communications‘ SuperNAP data center, told GigaOm that the research is worth following as low-latency networking inside the data center can be a bottleneck today for applications that range from financial trading to trying to move gigantic data sets around.

TR reports Ms. Zheng and her colleagues are now working on building a prototype data center to put their solution into practice.

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Cable mess under a raised floorHaving just done a small data center cleanup, the idea is appealing. We pulled out 2 generations of cabling, IBM Type 1, and a bunch of Cat 3 multi-pair out from under the deck.

Ms. Higginbotham says the choice of 60 GHz for the data center is a smart move. Intel is pushing 60GHz for consumer use, under the WiGig brand (I wrote about WiGig in 2010 here). This means the chips would be cheap.

Some of the possible security issues raised by running Wi-Fi in the data center are tempered by using the 60Ghz range. She says if you are worried about someone standing outside the data center trying to eavesdrop on the data you are transmitting the 60Ghz, signals deteriorate rapidly.

Of course, change is hard and data center guys are going to have to learn wireless and top-of-rack switches would have to get radio cards installed. The Wi-Fi reflective panels would have to be installed on the ceiling of the data center and the servers would need a signal-absorbing surface so the Wi-Fi signals don’t continually bounce around the data center.

Just if you are confused about WiGig, Wi-Fi, and IEEE, EETimes says, “WiGig forged a deal with the Wi-Fi Alliance so its 60 GHz approach can be certified as a future generation of Wi-Fi. The group has aligned its technical approach with the existing IEEE 802.11ad standards effort on 60 GHz.”

Now if only they could do wireless electricity……..

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Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.

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| February 17, 2010
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Wireless Gigabit

WiGig AllianceThe Wireless Gigabit Alliance has completed specs for a technology designed to deliver as much as 7 Gbps of wireless bandwidth in the 60 GHz band. The new technology, WiGig has the support of technology giants such as Intel, Broadcom, and Atheros. The technology is expected to have enough capacity to deliver high-def video streams up to 10 meters. WiGig’s anticipated road map includes system certifications in 2010 and WiGig based products to market in 2011.

Supplement other wireless technologies

According to the WGA, WiGig is not designed to replace 802.11 or Bluetooth but rather to supplement it. WiGig is a device-to-device (p2p) network and does not need a central hub or router that could easily turn into a congestion point. WiGig uses beamforming to extend its range beyond the 10-meter range and will automatically switch to 802.11n Wi-Fi.  “Our technology is backward compatible with existing Wi-Fi, and we fall back to 802.11n and 802.11g when we can’t connect at [7 Gbps] speeds,” Ali Sadri, told TechNewsWorld. “We’re based on 802.11, so our spec is not replacing Wi-Fi but extending it to 10 to 20 times faster than Wi-Fi.”

“By complementing Wi-Fi and enabling multi-gigabit speeds, the versatile specification is a very significant achievement on the road to the next generation of wireless LAN products,” says Craig Mathias, a Principal with the wireless and mobile advisory firm Farpoint Group.

Integrate WiGig into Wi-Fi chipsets

It is reported that Intel, Broadcom, and Atheros all have plans to integrate WiGig into Wi-Fi chipsets. “Ultimately, the question is how many different kinds of radios do you really need?” says Farpoint’s Mathias, “There’s not just competition from Wi-Fi and wireless HD but also cellular technologies such as 3G, LTE or WiMax … A lot of people anticipate 60 GHz products that will include 2.4 and 5 GHz Wi-Fi as well,” said Bill McFarland, chief technology officer of Atheros, and a WiGig member. “I definitely think we can support tri-band at 65 nm,” he added.

WiGig will include protocol adaptation layers to support specific system interfaces including data buses for PC peripherals and display interfaces for HDTVs, monitors, and projectors. WiGig will include advanced security and power management for WiGig devices. “We’re rapidly paving the way for the introduction of the next generation of high-performance wireless products – PCs, mobile handsets, TVs and displays, Blu-ray disc players, digital cameras, and many more,” said Doctor Ali Sadri of Intel and president and chairman of the Wireless Gigabit Alliance

The need for fast wireless data transfer plays into two big trends: the proliferation of multimedia and the increasing cable clutter that users have to deal with. “NVIDIA recognizes the general market trend toward wire-free interfaces. Today, display interfaces are at an inflection point where the next generation solutions will feature wireless display connections for PCs, game consoles, notebooks, and mobile devices with PC monitors and TVs,” said Devang Sachdev, Technology Marketing Manager at NVIDIA and WiGig Board Member.

60 GHz loses strength quickly

The biggest knock against WiGig is that signals at 60 GHz get absorbed by oxygen, meaning they lose strength quickly. Steel or concrete walls and even people in the room can be degraded or stop the 60 GHz signal. However, Intel’s Sadri says there is a solution. A 60 GHz antenna is just 2.5 millimeters long,  small enough that a lot of them can be packed into even a thin TV set or a mobile handset. Put 32 antennas on the transmitting and receiving ends, and you can send enough steered beams to compensate for the losses the signal experiences over distance.

In the 60 GHz spectrum, WiGig is likely to run into some competition. The IEEE is introducing a follow-up to 802.11n Wi-Fi standards called 802.11ad.  The IEEE 802.11ad standard will also be based on the 60 GHz spectrum but is not expected before 2012.  Mathias says, “The WiGig Alliance hopes to get a head start now and they might submit their standard to the 802.11ad group to be included in the specification.” The Wireless HD consortium also supports a third 60-gigahertz wireless networking plan for uncompressed HD video. Sony and Samsung are backers of all three 60 GHz plans.

It is likely that IEEE 802,11ad and Wireless HD will find it hard to compete against a general-purpose WiGig standard that can do uncompressed wireless HD video and more.

Members of the WGA include:·

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Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.

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| February 27, 2009
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HDTV over Wi-Fi

HDTV over Wi-FiTelephonyOnline has an article speculating that wireless high definition television will be available this summer. Celeno Communications, an Israeli start-up backed by Cisco, manufactures Wi-Fi chips. Their semiconductors can make Wi-Fi networks robust enough to deliver multiple high-definition television (HDTV) streams to PCs, TV’s or other consumer electronics devices. Celeno’s technology would deliver on a significant part of the anywhere, anytime video promise.

Celeno’s OptimizAIR technology will work with existing receivers such as set-top boxes, uses the 5 GHz spectrum. OptimizAIR uses standard PHY and MAC layers. It uses proprietary algorithms that the company says can double the throughput of standard 802.11 Wi-Fi. It can also increase the range of the Wi-Fi signals as much as eight times. Celeno’s technology additions include Spatial Channel Awareness and Beam-Forming MIMO (multiple inputs, multiple outputs). The company said it can stream HD video 120 feet, through four brick walls and more than three floors.

 

Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.

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