Cognitive Networks 2 Priyesh

Cognitive Networks

PRIYESH

Need for Cognitive Networks A rich set of digital services is required. But they have limited data communication capabilities(e.g. C2000 system [3] based on TETRA).  Public telecommunication networks like GPRS unrelaible. Networks could exploit different protocols.  They could work in different frequency bands. High performance ad hoc networks for instant internet access.

Evolution • Radios • Software defined radios • Improvement in programmable technologies like tunable broadband antennas and programmable DSP cores, ASICs and FPGAs • FCC’s report • Cognitive radio

Cognitive Network  Communication process with wireless nodes operating in different parts of the spectrum but residing in the operation area of described network is impossible. That is why by giving nodes the capability of spectrum scanning (not only in frequency domain but also in time and space) and automatic tuning to the desired band we could extent their communication capabilities.  Scanning the vast range of spectrum looking for underutilized bands establishing communication in it.  It has to predict what the user is trying to send/receive and change its transmission parameters according to the forecast.  It might even utilize information from other networks (like sensor networks) to decide about the way it should communicate with the ambient.

Basic blocks  Ad hoc networks coordinating point for the rescue operation simultaneously giving the nodes the ability to decide for themselves how they will communicate (which is the foundation of cognition).  Adaptive OFDM modulation. adaptive OFDM which is the variable assignment of carriers to the most suitable band.  One of the building blocks of OFDM modulator is the DFT transformer could be used as an efficient spectral analyzer.

Working  The cognitive-radio devices have two important functionalities: spectrum sensing and adaptation.  A secondary terminal first senses the spectrum environment in order to learn the frequency spectra unoccupied by primary users. Once such a spectrum hole is found, the secondary terminal adapts its transmission power, frequency band, modulation, etc., so that it minimizes the interference to the primary users. Even after starting the transmission, the secondary terminal should be able to detect or predict the appearance of a primary user so that it makes the spectrum available for the primary user. Basically, the primary users should not change their communication infrastructure due to these operations.  Thus, these sensing (including the detection) and adaptation of the secondary users must be done independently of the primary users.

Working 2

System X with ensed frequency

Cognitive radio F SS(F re quency Spectrum Scanner ) is respon sible for lookup of availab le bandw idth

SR M(Sp ectrum resource m anag er ) analizes the availab e banw idth accord ing som e specifie d criteria

F SS

AD C

F ront-end

AD C

BBP

SR M

R eceived bits

F ront-en d

D AC

BBP

T ran sm itted bits

X AM

C ontrol inform ation

F ront-end

XAM(T x/R x Algorith m m anag ) uplo ads appropria te softw ar toand co ntrols com m u nication ad ho c dom ain

Nodes in the IAN constitute of: 1. personal nodes: small, low powered, small spectrum range for cognitive capabilities. 2. vehicle nodes: bigger, usually accumulator powered, bigger communication capabilities, bigger spectrum range for cognitive capabilities. Usually they serve as gateways.

Physical group of nodes (nodes that share the same transmission parameters).

Logical group of nodes (communication user group) communicating to accomplish specific task.

Gateway node. JAN (Jurisdiction Area Network) is responsible for managing the group of IAN networks. Most of the nodes have a gateway capability for transferring traffic from ad hoc network to other nodes of JAN. This network might be fixed or wireless.

Group of ad hoc network IAN (Incident Area Netwo They are temporary in na they form and dismantle depending on situation du disaster recovery.

EAN (External Area Network), e.g. Internet, is the fixed network to which all the traffic from JAN is directed.

Complete rescue network developed in AAF project

Progress  Handling ultra wideband and analog voice waveforms on the same equipment  Developing a powerful but compact radio abstraction language that enables downloading of new waveforms, and keeping costs low (around $25).  The initial market will be homeland security and first responders  Mass production if the prototype is successful commercial telecom market in cellular phones, PDAs, and personal computers. There may be military applications as well.

Advantages  Cognitive raio makes it easier for manufacturers to introduce and spread new technologies thanks to the increase of license-free operations (i.e. the secondary use of the licensed band).  This also helps small venture companies to start new wireless businesses.  System operators get more opportunities to utilize their owned spectrum by renting it to other users or system operators.  Reduce the burden for large operators to keep expensive licensed spectrum.  Users can get new services with cheaper prices, but also with higher quality.  International roaming capability to users since terminals can sense and understand the communication environment abroad, and adapt their transmission according to the spectrum environment in different countries.  The government, the benefit is not only limited to the efficient use of the natural resource of radio spectrum.  The increase of the available radio resource can stimulate the invention of novel technologies, and can enhance the worldwide competence in this field.

Disadvantages  Costly  Legality

Thank you