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rick merritt
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Re: Beam forming phased array antennas
rick merritt   1/13/2014 1:57:19 PM
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@Les: How accurate does location need to be for beam forming? Can better GPS do t? If not, what tech can that fits into mobile size/power requirements?

rick merritt
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Re: Beam forming phased array antennas
rick merritt   1/13/2014 1:55:58 PM
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@Les: How accurate does location need to be for beam forming? Can better GPS do t? If not, what tech can that fits into mobile size/power requirements?

zewde yeraswork
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future research
zewde yeraswork   1/13/2014 10:25:18 AM
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This is an exciting time for determining what kind of research will be conducted into the future. High-frequency roaming is one important challenge, as is linking millimeter and traditional services and dealing with skyscrapers and other blockages. But the fundamentals of the technology are already in place.

 

Les_Slater
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Re: 39 GHz in your smartphone
Les_Slater   1/12/2014 9:59:36 PM
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Kris,

Of course there're implementation issues but I believe such techniques would actually reduce the required power being transmitted per channel. All the necessary phase shifting would be done digitally before being presented to the DACs associated with the particular antenna elements. The resulting beam being directed only at the intended receiver would require less transmitted power for a given received signal strength, sort of the equivalent of antenna gain. And as I said previously such techniques at base station receiver would result in improved signal to noise ratio.

The bigger picture is this is being proposed as a possible means to alleviate spectrum resource limitations. This would fall under space division multiplexing. And of course the need to find a way around spectrum limitations implies greater amounts of communications with higher throughputs, hence 5G, 6G, etc. THIS is what will tend to contribute to higher amounts of power surrounding us. But techniques such as being proposed here will also have the potential to minimize the power required.

Les

PS, these techniques are already, in some form, being applied in modern wifi routers such as those complying with 802.11n, ac and presumably, ad.

krisi
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Re: 39 GHz in your smartphone
krisi   1/12/2014 8:28:27 PM
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Sure Les, that might be theorethically possible...I think I run some calculations about this with my grad students at some point in the past...the power dissipation will be enormous though...which bring me to the third limitations of the bandwidth: how much power do we really want to burn by sending those wireless signals? Kris

Les_Slater
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Re: 39 GHz in your smartphone
Les_Slater   1/12/2014 5:17:42 PM
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Also, the part about forming a beam in only one direction is not true. With high accuracy DACs driving each antenna element one can digitally assign multiple beams at multiple or same frequencies. The same is true of receiving. I believe the digital signal processing would relatively simple. The DACs and ADC would need lots of bits and it would help if all amplifiers were sufficiently linear. The steering and focussing would help the signal to noise ratio. 

Les_Slater
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Re: 39 GHz in your smartphone
Les_Slater   1/12/2014 5:07:12 PM
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I was was going beyond simple beam formation and raising using a synthetic aperature. Not only can a 'beam' be steered but also focussed. The term 'beam' is not be adequate for such spot delivery. It could be several beams, from several physical locations, where only at the target destination would the waves be in proper phase. To accomplish this would require all transmitters to have absolute time accurate in the order of femto seconds.

krisi
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Re: 39 GHz in your smartphone
krisi   1/12/2014 4:42:48 PM
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Beam forming is an interesting technology and has its place for use for sure...but let's keep in mind it has been known and used for years in military applications...plus you can send a beam in one direction...I don't see how this can really improve throughput in 360 degree circle...Kris

Les_Slater
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Re: 39 GHz in your smartphone
Les_Slater   1/12/2014 2:38:58 PM
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I don't think we should underestimate beam forming as a potential approach to alleviating spectrum limitations. The technology can get rather esoteric but we really haven't begun to explore synthetic aperatures at the base station level, nevermind with the mobile devices themselves.

krisi
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Re: 39 GHz in your smartphone
krisi   1/12/2014 11:36:22 AM
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The way I see there are two hard limits eventually. First is the amount of bandwidth human is capable of absorbing (we only have so many eyes, ears, and bran cells). You can see young people working on laptops with multiple windows, listening to the music and texting on their phones at the same time. They look to me close to their bit absorbing capability already. Second is the physics of wireless communication. The mount of spectrum is fixed and just can't continue going up with frequency as teh signal attenuation beyond 60 GHz is huge. Yes, you can do beam forming, play coding tricks, design better modulation schemes, etc. but there is probably a limit to that too.

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