Presentation 06022011 DIDO

Transcript of Presentation 06022011 DIDO

Distributed Input Distributed Output(DIDO)Communication Systems

Randeep Yahathugoda

Electrical engineering and Computer Science,Colorado School of Mines

February 7, 2012

Randeep Yahathugoda Distributed Input Distributed Output(DIDO) Communication Systems
Introduction

I Two Basic problems with any wireless communication methodare

1. Capacity is not enough2. Reachability is not enough

I It was believed and proven that the fundamental capacity of awireless communication medium is limited by Shannon-Hartleytheorem.

I Theorem states that the maximum rate at which informationcan be transmitted over a communication channel of aspecified bandwidth in the presence of noise is given by,

C = B.log2(1 + S/N)

(where C = channel capacity, B = Bandwidth, S = Received Signal power, N = Noise power)

I The DIDO system claims that the maximum data rate can beincreased beyond the limit defined by the Shannon Theorem.

Introduction


1. Capacity is not enough

2. Reachability is not enough



C = B.log2(1 + S/N)



Introduction





C = B.log2(1 + S/N)



Introduction





C = B.log2(1 + S/N)



Introduction





C = B.log2(1 + S/N)



Introduction





C = B.log2(1 + S/N)



IntroductionBackground

I Due to increased popularity of mobile data communicationamong people, there is ever increasing demand for higher datarates.

I Approaches like MIMO(Multiple Input Multiple Output ) (with3G and LTE) or beam-forming are used to increase the shareddata rate limit by a factor of 3 to 4 in certain situations.

I Conventional multi-user systems treat Spectrum and Channelas the same thing.

I Then the users in the same region shares the same spectrumand same channel.

I So maximum data rate available for them is limited by theShannon theorem - Which is always not enough current.

IntroductionBackground Cont...

I Important thing to note is that Shannon theorem is aboutchannel data rate limits, not the spectrum data limit

I Techniques like MIMO and beam-forming try to increase datarates by creating some independent channels using the samespectrum in a single area.

I So the Shannon theorem applies to each channelindependently, and increases the capacity for the samespectrum.

I And what DIDO claim to do is, to eliminate the effect ofShannon limits completely by forming unlimited number ofmultiple channels from the same spectrum using specializedsignal processing techniques


I DIDO is capable to give a separate channel to each user whois sharing the same spectrum with many other users

I Shannon theorem applies the each channel owned by the usersseparately, not to the spectrum as a whole

I So each user gets the maximum capacity available in thespectrum

I This is a huge thing as it increases the capacity of the Wirelesssystem without bounds and can cater for unlimited number ofsubscribers using the same bandwidth (A scarce resources)

How current Wireless Communication Systems workExample WI-FI

I When a single user with a computer connects to a singleWi-Fi access point and there are no other users of thespectrum (Frequency range)(e.g. no other Wi-Fi, Blue-toothor other devices that share the same spectrum) in the areaand the User is within optimal reach (the blue circle) of theWi-Fi AP , then if the User receives 100% of the data rateavailable in the channel.

How current Wireless Communication Systems workExample WI-FI Cont .....

I What happens if more than one user in the same area ?

I User 1 clicks a video link on website 1 and User 2 clicks avideo link on website 2, the video data from website 1 is sentto AP 1 and the video data from website 2 is sent to AP 2,each AP modulates a radio signal with the video data andtries to transmit that radio signal.

I Each AP quickly discovers there is something interfering withits transmission: The AP using the same spectrum.


I Wi-Fi has several techniques to deal with interference, but thenet effect is that they all share the channel, and as aresult,First User uses the spectrum while second User standsby idle.

I Each user gets a data rate of 50%


I Wi-Fi has several techniques to deal with interference, but thenet effect is that they all share the channel, and as aresult,First User uses the spectrum while second User standsby idle.

I Each user gets a data rate of 50%

How DIDO works

I For example consider five different users are trying to accesswebsites using DIDO.

I After users request data, the websites sent them to the DIDOdata center.

How DIDO works

I For example consider five different users are trying to accesswebsites using DIDO.

I After users request data, the websites sent them to the DIDOdata center.

How DIDO works cont...

I The DIDO data center process the data and creates fivedifferent waveforms and send to relevant DIDO access points.

I Here, there is a contrast from conventional systems like Wi-Fiwhere they make the waveform in the antenna or AP

I And each of them transmit there respective waveformssimultaneously.

I Waveforms are calculated such a way that the resulting sumof the each waveform at each user generates a cleanmodulated waveform carrying the intended data for that user.So each user receives their intended data

I Here to each user it seems like they are using the wholespectrum alone and able to use full Shannon limit of thechannel.


I At the start of the communication DIDO access pointsexchange test signals with the user devices.

I By analysing what happened to these test signals as theypropagate through the wireless media, the DIDO Data centerdetermines what will happen when it transmits data signalsfrom the access points to users, and how the simultaneouslytransmitted signals sum together when received by each userdevice.

I DIDO Data center uses this analysis, to create precisewaveforms for all of the access points that, when transmittedat once will sum together at each user device to create aclean, independent waveform carrying the data requested bythat user.


I A DIDO channel can be visualized as a small 3D sphere thatsurrounds the antenna of a user device.

I Within that sphere, the channel for that particular user exists.Outside of that sphere, it does not

I If there are 10 users in a DIDO network, there are 10 spheres

I As a user device moves, the sphere moves with it.


I Basically DIDO uses orthogonal frequency-divisionmultiplexing (OFDM) and further uses link-quality matrices todetermine different OFDM tones to be used to communicatewith each of the DIDO users.

I DIDO technology claims that in some configurations it canhave a range approximately 250 miles in radius and it is partlydue to sky-wave phenomenon.

Advantages of DIDO

I Unlimited Capacity using a limited bandwidth (No Theoreticallimit)

I Remarkable reachability (Can cover a radius of a 250 mileswith a single antenna)

Advantages of DIDO

I Unlimited Capacity using a limited bandwidth (No Theoreticallimit)

I Remarkable reachability (Can cover a radius of a 250 mileswith a single antenna)

Special uses of DIDO

I Can be used to give coverage for rural areas, because ofexcellent reachability

I Can be effectively used in disastrous situation(ex: after naturaldisaster), where building infrastructure quickly is impossible.

I Can be used for information gathering for large areas, becauseonly one DIDO transmitting antenna can cover a huge range.

DIDO and Computer Science

I It seems that computational capability of the DIDOdata-center will act as an limiting factor for the capacity ofthe system.

I Data center does lots of intense mathematical operations likeAdvanced Signal processing, Matrix related calculations whichcan have high demand on computational resources.

I CS people can theoretically and practically analyse capacityand performance limiting factors of the system

I CS people can define efficient algorithms to do Theaseintences mathematical operation, better than others

I CS people can define new data structures to make processingefficient

I CS people can define specialized Operating systems to beused for DIDO data centers

End

I Reference : Distributed-Input-Distributed-Output (DIDO)Wireless Technology A New Approach to Multiuser Wirelessby Steve Perlman, President & CEO, Rearden CompaniesAntonio Forenza, Ph.D., Principal Scientist, ReardenCompanies, www.rearden.com

I THANK YOU !

Presentation 06022011 DIDO

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