Wi-Fi

How nanotechnology helps Bluetooth and Wi-Fi work together

Bluetooth and Wi-Fi share frequencies in the 2.4 GHz ISM band, causing signal degradation when both are enabled in the same device. That's no longer an issue, thanks to antenna systems based on nanotechnology.

Oddly enough, this article came about because of a repair call. I received a voice mail from a friend, his Wi-Fi wasn't working. After initial checking, it appeared the Atheros AR9000 series 802.11n/Bluetooth combo mini card was to blame. Still, I wanted to check the antennas and feed cables. To my surprise, there was only one antenna.

My friend wasn't the least bit interested in this new discovery, just wanting his netbook back in working order. On a hunch, I reseated the board. That's all it took. On my way home, I started wondering about something. What happens if both Bluetooth and Wi-Fi are enabled and transmitting at the same time?

Previous article may explain

For reasons unknown, I remembered an article I wrote two years ago: iMAT: MIMO without multiple antennas. The post was about how metamaterials are used to create antenna systems that overcome something called coupled interference. To understand what that means, let's review MIMO.

MIMO causes coupling

MIMO technology requires multiple transceivers, each with their own antennas. That need invites unwanted signal coupling, because the small package size does not allow sufficient physical separation of the antennas. It's likely a significant portion of one transceiver's output is being absorbed by one of the other transceiver/antenna systems built into the Wi-Fi device.

The solution

Since it's not practical to make Wi-Fi devices larger, another solution is needed. Enter SkyCross, a global designer of high-performance antenna solutions. SkyCross came up with iMAT (isolated Mode Antenna Technology). This technology mates a single antenna to multiple transceivers, abating the coupling phenomena. The following illustration (courtesy of SkyCross) depicts one configuration:

The next SkyCross graph displays how using a single antenna with multiple feeds has less coupling than multiple antennas:

Reducing coupling is important, by allowing more power to be radiated where it's needed. For more details, the SkyCross paper, "Isolated Mode Antenna Technology," is a good place to start. Last week, I wrote about Beceem Communications and how their new chip set will seamlessly transfer between WiMAX and LTE, I wonder if that would be a good fit for iMAT. Possibly, but more to the point, SkyCross has created iMAT systems to solve another thorny problem.

Next accomplishment

Remember my friend's netbook and my pondering about Bluetooth and Wi-Fi working together. I am not sure if it's curiosity or what, but I wanted to find out how that worked. It didn't take long. SkyCross once again provided the answer.

iMAT keeps them separate

There is a news release on the SkyCross Web site explaining how their researchers used iMAT's features to create a solution, whereby Bluetooth and Wi-Fi coexist. I'll let them explain:

"In this instance, iMAT enables a single antenna to have one feed dedicated to Wi-Fi and another feed shared with Bluetooth, which uses the chip set providers' time-sharing and adaptive frequency hopping algorithms. The very high, built-in isolation between the two feeds enables both to operate at the same time in a very small space."

The following diagram (courtesy of SkyCross) shows how iMAT differs from the conventional approach.

What's not to like. iMat decreases the number of required antennas from three to one. That reduces cost and saves valuable space. It also eliminates the coupling interference problem associated with multiple antennas in close proximity.

Final thoughts

I read about nanotechnology all the time. Yet, its potential never ceases to amaze me -- from the possibility of creating an electromagnetic cloak to what SkyCross has been able to accomplish. I'm glad I was more curious than my friend.

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Information is my field...Writing is my passion...Coupling the two is my mission.

28 comments
vigremrajesh
vigremrajesh

how abt the radiation difference in imat antenna..?

Sensor Guy
Sensor Guy

Mike, This will certainly reduce the weight of laptops and other devices. Good article. We are fast approaching the day that through dynamic programmable nano-technology we can build only one antenna for simultaneous reception and transmission all types of communications across all frequencies. The meta material cloaking is not as mature and ready for applications as this invention is, IMHO.

santeewelding
santeewelding

You are not glad. You are cursed -- with indefatigable curiosity. It is I am who are glad you are. Makes for good reading.

Daniel Breslauer
Daniel Breslauer

I nearly stopped using Bluetooth because it causes interference with WiFi. My entire household runs on WiFi. Once, our main external loudspeakers (used for movies and some music now and then) broke - the cable connected broke off, leaving the plug inside main loudspeaker with no way of getting it out of there. So, I found the perfect solution - a Bluetooth loudspeaker! Wasted perhaps $150 (it was 2 years ago, maybe more) on this Bluetooth loudspeaker, and a Bluetooth USB adapter for one older laptop. Turned out it was useless. Bye bye, Bluetooth. Since then I occasionally used the loudspeaker with a 3.5mm cable, which is also possible, but we got normal loudspeakers again to replace the old ones. The ideal thing for me would be to have loudspeakers with a LAN connection, so I could just hook them up to my router and send the laptop's audio output there. The first who makes such a device is going to be rich.

Michael Kassner
Michael Kassner

Ever wonder how two different RF technologies can exist on the same frequency without canceling each other out? Here is how.

Michael Kassner
Michael Kassner

But, I do not understand your question. What is really impressive is that metamaterial antennas and the requisite software are capable of directing the majority of the RF toward the remote site.

Michael Kassner
Michael Kassner

I am just amazed at it's possible. I love "outside the box" thinking and both of these technologies certainly are. I can hardly wait until this technology gets to amateur radio antennas. Directional beam antennas will no longer be required.

Michael Kassner
Michael Kassner

I am curious to learn how this is significant to you. Your input means a great deal.

Michael Kassner
Michael Kassner

There are some Wi-Fi enabled speakers available. I have used speakers from this vendor: http://gadgetscrunch.com/oyster-wifi-speakers/ The ones I had were battery-powered. Which in a sense was cool. The neighbors could not figure it out. I would crank up the tunes and carry both speakers across the street and they were totally lost.

Old-Fart-IV
Old-Fart-IV

Michael -- another great article :) User never want to believe me that all the different "gizmos" they have to have for their different wireless connections could be interfering with each other. Then again, maybe I'm the smartest of the bunch: keep it simple. I'm using on-board WiFi, rather than all the fancy plug-ins they give to the marketers and sale folks.

slam5
slam5

I don't really understand why BT and wifi will interfere with each other? while both use ISM frequency, they use completely different encoding technology. BT use frequency hopping (FHSS) and 802.11 use either ODFM 802.11g or CSMA/CA. FHSS (frequency hopping) suppose to jump from one channel to another while 11g or 11b fix the center frequency. By correct choosing of frequency on 802.11g. I have wifi and BT co-existing in my place with no visible interference. Interesting you found there was a problem..

JCitizen
JCitizen

the health concerns over close range radiation effects?

Sensor Guy
Sensor Guy

I'm looking for the IMAT of fractal antenna that can be configured dynamically so a sensor can dynamically increase its wireless capabilities to send its data back to its owners.

sbbloom
sbbloom

I'm a ham (KD5HVO). I followed Cebik's antenna theory threads for years. I remember reading several stories about experimenters building quite elaborate "fractal" antennas. These achieved some success in getting an HF 1/2 or 1/4 wave antenna down to a footprint the size of a car roof. Unfortunately, the usable bandwidth is quite small. The old curse of wanting a DC to Daylight solution. I still have interference problems with my 2.4ghz phones, with my WiFi. I just have to select which WiFi channels I use in my network AP. Keep these articles coming. Reading even 1 or 2 of these a month makes it worth it. I just don't have the time to dig like I used to. Thanks, Stu Los Alamos, NM

JCitizen
JCitizen

Don't know whether I'm coming or going! :( :)

Michael Kassner
Michael Kassner

Is the problem. The receivers can be overwhelmed if they are not configured and filtered correctly. It also degrades reception of weak signal. The problem is less when a combination device is used as the manufacturer is aware of the interference. The following link is a good white paper on interference: http://www.ce-mag.com/archive/01/05/lansford.html

Michael Kassner
Michael Kassner

Talk to SkyCross. They have a great R&D and engineering program. I have had a few conversations with Paul Tornatta. He is very knowledgeable.

JCitizen
JCitizen

This would radically give HAM operators world wide redundancy. This could really enhance emergency communications world wide in large natural disasters! Maybe even nuclear? Hey, with dispersed radio/internet, it could be ultimately survivable! Many HAM operators in my neck-o-the-woods have old vacuum tube sets which are durn near impervious to EMPs.

Sensor Guy
Sensor Guy

This is a crucial area of technology for many of us.

Michael Kassner
Michael Kassner

Amateurs are all about helping. Let me know if you want to go for it. I and others can help with the test as well as equipment. In fact, you really don't need equipment to start. You can use a technology called Echolink. It marries the Internet with amateur radio. http://www.echolink.org/

JCitizen
JCitizen

But I'd have to scrape the money up for the radio next. I'm hoping 1st quarter will be better this year, so I can get back to living, instead of nickle and dime-ing. I wonder if the association would let me use their unused TV tower? Uh Oh! Hey! I know! I could donate it to the center and we all could use it(for emergencies of course)* *I live in a government project!

Michael Kassner
Michael Kassner

That you have a CB license. I will so bug you now to get your amateur license.

JCitizen
JCitizen

but that was Citizen Band. However my name had no "K" in it. The FCC seems to love putting the letter K in wireless station IDs. You can tell how old I am to still have a CB license, however they are no longer needed; and haven't been since the late '70s or early '80s, I believe.

santeewelding
santeewelding

Weren't you, that the "K" can mean, Kassner.

Michael Kassner
Michael Kassner

I get excited when I from other amateurs. That said, please get me up to speed about fractal antennas. Are they different from metamaterial antennas. I say that because, I have not read about an antenna below the microwave frequency range that was using adaptive technology. I am K0PBX and would love to share experiences. 73s

JCitizen
JCitizen

why my fancy blue-tooth media center keyboard just didtn't get alone with my PC. It and the wireless G card were fighting each other constantly. I thought maybe it was the drivers, but now I know. Oh well, I gave it away to a friend that is happy with it! I wouldn't doubt if my blue-tooth card built into the PC wouldn't do the same if I didn't have it disabled. HP just never did give me a driver that worked.

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