Archive for wi-fi

| March 1, 2018
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MIMO Antennas Explained

MIMO Antennas ExplainedWave 2 of the IEEE 802.11ac Wi-Fi standard has been out for a while now. Wave 2 Wi-Fi can support speeds up to 2.3 Gbps. One of the techniques used to generate the increased speeds of the 802.11ac networks is multi-spacial streams or several streams of the same Wi-Fi signal radiating out from several antennas. The multiple antennas are the most noticeable indicator that an access point is 802.11ac capable, especially in the consumer market.

Multiple-Input Multiple-Output

The technology behind using several antennas is called Multiple-Input Multiple-Output (MIMO). MIMO antennas have two or more antennas in a single physical package and are designed for use in IEEE 802.11n/ac Wi-Fi networks. MIMO makes antennas work smarter by utilizing multiple antennas to combine data streams arriving from different paths and at different times to increase data throughput and range compared to a single antenna using the same radio transmit power. By transmitting multiple data streams at the same time, wireless capacity is increased.

Additionally MIMO antennas improve link reliability and experience less fading than a single antenna system. MIMO antennas use spatial diversity technology, which puts surplus antennas to good use. When there are more antennas than spatial streams, the antennas can add receiver diversity and increase range.

Radio-wave multipath

Asus AC5600 routerMIMO technology takes advantage of a natural radio-wave phenomenon called multipath to improve wireless performance. In the past, multipath caused interference and slowed down wireless signals. With this iteration, Wi-Fi takes advantage of multipath. With multipath transmitted information bounces off walls, ceilings, and other objects, reaching the receiving antenna multiple times via different angles and at slightly different times

MIMO technology takes a single data stream and breaks it down into several separate data streams and sends it out over multiple antennas. This technique provides redundancy. The receiving MIMO antenna will “look” at each stream being sent to determine the strongest one to choose.

Legacy wireless devices use Single-Input Single-Output (SISO) technology. These devices cannot take advantage of multipath, and can only send or receive one spatial stream at a time.

802.11ac Wave 2 MIMO

A new version of MIMO has been developed. TechHive reports that Multi-user multiple-input, multiple-output (MU-MIMO) technology, enables AP’s to transmit and receive data from multiple Wi-Fi devices at the same time. Although the devices must also support MU-MIMO to utilize it, they aren’t required to have multiple antennas.

MU-MIMO was introduced with 802.11ac Wave 2. Wave 2 MU-MIMO support is required on both the access point and client device to work. It operates in the downstream direction, access point to the client, and allows an access point to transmit to multiple client devices simultaneously. This means networks with a dense number of users in an area, such as public Wi-Fi hotspots, could be able to handle more Wi-Fi devices.

TechHive warns the biggest caveat of MU-MIMO is it doesn’t directly improve the wireless speeds of uplink connections.

Only a handful meet the criteria today

MU-MIMO technologyIt’s also important to note that the only way to gain the full benefit of MU-MIMO is when the technology is supported on both the access point and the device that’s connecting to the AP. So in addition to having an 802.11ac adapter onboard, the client must explicitly support MU-MIMO—there are only a handful of adapters that meet that criteria today.

Finally, TechHive says MU-MIMO works best with stationary Wi-Fi devices. If users are walking around while watching a video on a smartphone or tablet, they are not going to get the full benefit of MU-MIMO even if that device supports it. Your router might even limit that connection to using SU-MIMO, so that the connection doesn’t negatively impact stronger MU-MIMO connections.

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The client issue is the main reason 802.11ac Wave 2 will not be widely used in the enterprise. it is a big issue to keep the clients up to date to match the AP version. In fact, Zeus Kerravala at NetworkWorld points out that many of the high-volume manufacturers, such as Apple and Samsung, are skipping 802.11ac Wave 2 and plan to support IEEE 802.11ax in the future.

So skip Wave 2 devices in the enterprise and stick to an 802.11ac Wave 1 AP, and get exactly the same performance as its higher-priced Wave 2 counterpart.

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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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| November 7, 2013
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802.11ac Wi-Fi – Don’t Bother Yet

802.11ac Wi-Fi - Don't Bother YetThe new iPads are here! The new iPads are here! There’s no 802.11ac here! But that’s expected. Experienced Apple watchers know that Apple likes to let new radio technologies mature before they integrate them into their new idevices. So that means most enterprises can slow their plans to upgrade their Wi-Fi to the new standard according to Kevin Fitchard at GigaOM.

The new iPads are hereThe latest Apple (AAPL) tablet doesn’t sport the new soon-to-be-completed IEEE 802.11ac standard, even though Apple’s latest generation routers, PCs, and laptops all support it. GigaOM reports Apple is providing is a speed boost to the now thoroughly established 802.11n networking standard in the form of multiple-input multiple-output (MIMO) smart antenna technology. Like many Wi-Fi routers on the market, the iPad Air has dual antennas, allowing it to wend two parallel paths over the unlicensed airwaves. The MIMO implementation will double the speeds at which the iPad can access Wi-Fi networks, according to Apple.

The Wi-Fi Alliance only began certifying commercial 802.11ac devices in June, and even those devices only incorporate partial versions of the full 802.11ac spec. The IEEE isn’t expected to fully complete the standard until 2014. Very few smartphones and tablets have ac embedded as of yet, though the technology is making its way into consumer and enterprise routers and PCs, including Apple’s newest MacBooks and iMacs.

iPad AirBut waiting another year for 802.11ac-enabled iPhones and iPads also means we’ll probably have to wait another year before we see wide-scale adoption of the standard in public hotspots and access points. Unlike in the home, most outdoor and public Wi-Fi connections are made over mobile devices, not PCs.

In an interview with GigaOM, Boingo VP of corporate communications Christian Gunning said it hasn’t turned up 802.11ac in any of its hundreds of thousands of owned and managed hotspots yet, simply because it’s seeing very few devices with ac radios trying to access its network.

higher-powered 802.3at Power over EthernetFierceCIO‘s Paul Mah offers more reasons to delay the roll-out of 802.11ac. The advanced 802.11ac radio is more power-hungry than earlier iterations of Wi-Fi. So it will more likely need the use of the higher-powered 802.3at Power over Ethernet (PoE) to run 802.11ac with all its bells and whistles. It is possible that businesses still on 802.3af PoE (rb- Majority) may well have to incur extra infrastructure costs to deploy 802.11ac today. Mr. Mah contends that it is yet to be seen if improved 802.11ac chipsets will allow firms to stick with legacy PoE. (rb- For a refresher on PoE, check out these posts 802.3af and 802.3at)

Another consideration according to FierceCIO is clients. The handful of business-grade 802.11ac wireless APs on the market today typically support three spatial streams, which allows for a (theoretical) maximum data rate of 1.3Gbps in the 5GHz band. Though this is a significant improvement over 450 Mbps 802.11n, the dearth of 802.11ac client devices renders this a moot point. Some will argue that Apple did incorporate 802.11ac into the new MacBook Air laptops.  However, they did not include it in the new iPads, or the iPhone 5S and iPhone 5C smartphones. And with no smartphones or tablets equipped with 802.11ac capabilities today, this does make deploying it a rather pointless strategy for BYOD.

802.11ac "second wave"Finally, Mr. Mah points out that while 1.3Gbps is a good speed to have, we should keep in mind that 802.11ac does have a theoretical maximum speed of 7 Gbps. A “second wave” of 802.11ac that implements four or more data streams for much faster speeds should be arriving in the second half of 2014. He says current signs are that this second wave of 802.11ac devices might need new processor chips–which means you will have to buy new 802.11ac hardware to benefit.

GigaOM’s Fitchard stresses Apple’s influence when it comes to popularizing new technology, he says the iPhone and the iPad’s reach shouldn’t be underestimated. As an example, new Passpoint-certified phones have been out for more than a year, but it wasn’t until Apple started offering support for Passpoint’s automatic login technology in iOS7 that the wireless industry took notice. It was only after Apple made iOS7 publicly available, that Boingo started Passpoint trials.

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I’m not saying 802.11ac is a bad thing, but enterprises need to ignore the hype cycle and make decisions that are best for them and not the multi-billion dollar networking industry. IMHO 802.11ac is still immature, there are few devices out there that can fully take advantage, the full feature set is not fully implemented in silicon and you finished the upgrade to 802.11n yet?

What to do?

What does your wired network look like? Are you still connecting your AP’s at 100 Mbps? That is a bottleneck with 802.11n.

Do you have enough juice? What is your PoE status? Do you have enough PoE+ ports? Are they being used for just an access port – wasting the extra costs of a PoE port?

Both switches cost money, is there a budget available for these items or is IT going to spend an operational budget to address a structural issue?

 

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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| 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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| January 4, 2011
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iPad Driving Wireless Networks

iPad Driving Wireless NetworksJuniper (JNPR) recently loosened up its purse-strings and bought Trapeeze Networks to fill the most obvious hole in its product line. Juniper purchased the WLAN vendor from Belden (BDC) for $152 million in cash. The Belden/Trapeeze relationship is something I never got, when I think Belden, I think cable, and connectors not wireless. NetworkWorld cites Gartner “…more than 60% of end-users purchased their WLAN solutions from the same vendors as their wired LANs, meaning that Juniper has likely been leaving a lot of opportunity on the table.”

David Yen, executive vice president, and general manager, Fabric and Switching Technologies, at Juniper (and owner of possibly the longest title in networking), told NetworkWorld that the industry is much more mobile, “it was time for us to include wireless.” GigaOm says that the purchase was a recognition by Juniper that the enterprise networks were going through a sea change, thanks in part because of a big upsurge in the number of mobile devices connecting to corporate networks. This proposition is backed up by a survey by BoxTone Mobile Service Management which found that 73% of the surveyed companies intend on deploying the Apple (AAPL) iPad as well as other iOS devices for use on their network within the next 12 months, with 25% of those companies set to deploy right away. More than 50% of those surveyed plan on deploying their own iPad app within the next 12 months, while 25% of those plan on deploying as many as three of their own iPad apps.

IT executives interviewed by WindowsITPro.com argue that the iPad isn’t for everyone, but is very well suited for users that consume more content than they produce, such as, e-mail and corporate documents. Another area where the iPad seems to be making inroads into corporate IT is as a device that displays content for cloud and software as a service (SaaS) business solutions.

Some of the iPad initiatives include:

  • Mercedes-Benz is using iPads on showroom floors according to ZDNET. MB uses the iPad to present and execute the various financing options for customers without having to go sit down in an office.
  • SAP the world’s largest business software developer has released an iPad app so that its customers can access their reports and corporate data with the iPad. ZDNET reports that SAP is also using and supporting iPads internally. Rob Enslin, the North American president at SAP, says that he now carries an iPad instead of a laptop when he travels. “It’s allowed me to almost run a paperless office,” said Mr. Enslin. He said that he uses the iPad to view business apps, briefing documents, customer information, and other corporate data.
  • ServiceMax has developed an iPad app for pushing the device as a modern solution for field service applications according to WindowsITPro.com
  • Rackspace has developed a configuration management tool for cloud data centers according to TechWorld

Dominic Orr, CEO of Aruba Networks (ARUN), told GigaOm that his firm expects to see future demand coming from corporations who are seeing a big shift in the way their networks are being used. “The network model has shifted from hotspots to ubiquitous and uniform networks access,” Orr said. Companies now want wireless access not only in boardrooms and hubs of productivity but also in stairwells, corridors, kitchens, and other areas. Why? Because the devices accessing the network are entirely different, he pointed out. “Our demand is being driven by smartphones and smartpads,” he said. In the past, laptops were used for wireless access, but it was difficult to walk around and use them as easily one can use a smartphone or an iPad. The smart devices, however, encourage anywhere computing, which, in turn, puts a different load on the networks.

Mr. Orr goes on to say that iPads and tablets are very multimedia-centric, which means folks are looking for good, solid, and even coverage across their entire campus, and not just in certain specific areas, Mr. Orr pointed out. “While netbooks and laptops have wired Ethernet built into them, the new smart devices can only access the Internet via mobile connections,” he added. “You either have 3G or Wi-Fi.” These demands for improved coverage have led the research firm Dell’Oro Group to estimates that the enterprise WLAN market will grow from $2.2 billion in 2010 to $3.4 billion in 2014.

Steve Jobs loves his iPad

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The iPad, and many new and emerging consumer devices, only have Wi-Fi connections network teams are going to face many challenges in the face of iPad adoption. Wi-Fi networks are viewed as a utility by employees, who expect to connect any device to any network to get connected. Underscoring a major societal and cultural trend of the connected lifestyle, Enterprise adoption of the iPad is part of the larger trend of consumerization of IT (which I have written about here, here, and here) in which companies are allowing employees to choose which tools they use.  The negative consequences of not allowing users to choose the products they want to use themselves simply aren’t worth it, according to Karl Ageberg, CIO at Lund University in a PCWorld article. That movement will also open the door to competing products from a growing number of Android-based tablets and Research In Motion’s upcoming PlayBook.

Some of the ways  iPads will force changes:

  • Internal IT security to deliver secure access methods for all consumer devices in general.
  • Security policy changes, to offer secure and controlled access to corporate data.
  • Network and application security design, to provide secure and controlled access to corporate data.
  • Network management to make sure mission-critical devices and applications get the required QoS and SLA required.
  • Mobile device management platforms ability to control access and storage of sensitive corporate data on these devices.
  • Support for consumer devices, owned both by the organization or by individuals.

Has the iPad breached your IT walls?

How has the iPad changed how you do business?

 

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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