next generation wireless networks: smart radios

1/37NETLAB Seminar 7 March 2007

NeXt Generation Wireless Networks: Smart Radios

Suzan Bayhan

[email protected]://satlab.cmpe.boun.edu.tr

http://www.cmpe.boun.edu.tr//~bayhan

mailto:[email protected]

http://satlab.cmpe.boun.edu.tr/

http://www.cmpe.boun.edu.tr//~bayhan


Outline

Problem Definition & Motivation

Software Defined Radio + Cognitive Radio

Standardization

What about Satellites?

Conclusion and References


Motivation

Going wireless more and more...

Lack of interoperability bw. different technologies

Lack of spectrum (???)


Spectrum Facts

Fixed Spectrum Assignment

Bandwidth is expensive and good frequencies are taken

Recent measurements by the FCC in the US show 70% of the allocated spectrum is not utilized

Time scale of the spectrum occupancy varies from msecs to hours

More clever radio

Frequency Agility----SPECTRUM SHARING

SOLUTIONSOLUTION


Solution

Joseph Mitola 1992 Software Defined Radio(SDR)

radio primarily defined insoftware, which supports a broad range offrequencies, and its initial configurations can bemodified for user requirements.

Joseph Mitola 1999Cognitive Radio(CR)

SDR + Intelligence


Outline



Standardization




SDR properties

Reconfigurable

Easily Upgradeable

Responds to the changes in the operating environment

Lower maintenance cost


If SDR technology is properly applied...it will facilitate this single platform design, and will also provide a path towards the realization of concepts such as

Reconfigurability (single platform concept)

run-time reconfiguration (run-time bug fixes)

and eventually self-governed learning (cognitive) radio.


FINAL GOAL...

UNIVERSAL WIRELESS DEVICE

that can seamlessly handle a range of frequencies, modulation techniques, and encoding schemes.


Some definitionsPrimary User (Licensed User)

the user which has an exclusive right to a certain spectrum band.In other words, the license holders...

No need to be aware of cognitive usersNo additional functionalities or modifications needed

Secondary User (Unlicensed User)Cognitive-radio enabled users

Lower priority than PUs


SPECTRUM HOLEA spectrum hole is a band of frequencies assigned to a primary user, but, at a particular time and specific geographic location, the band is not being utilized by that user.


Definition (1)

In the 1999 paper that first coined the term “cognitive radio”, Joseph Mitola III defines a cognitive radio as

“A radio that employs model based reasoning to achieve a specified level of competence in radio-related domains.”


Definition (2)

Simon Haykin defines a cognitive radio as “An intelligent wireless

communication system that is aware of its surrounding environment (i.e., outside world), and uses the methodology of understanding-by-building to learn from the environment and adapt its internal states to statistical variations in the incoming RF stimuli by making corresponding changes in certain operating parameters (e.g., transmit-power, carrierf requency, and modulation strategy) in real-time, with two primary objectives in mind:

· highly reliable communications whenever and wherever needed;

· efficient utilization of the radio spectrum.


Properties

Cognitive radio propertiesRF technology that "listens" the spectrum Knowledge of primary users’ spectrum usage as a function of location and timeRules of sharing the available resources (time, frequency, space)Embedded intelligence to determine optimal transmission (bandwidth, latency, QoS) based on primary users’ behavior

Cognitive radio requirements

co-exists with legacy wireless systems uses their spectrum resources does not interfere with them


Main Cognitive Functions

Spectrum Sensing

Spectrum Management

Spectrum Mobility

Spectrum Sharing


But...

Hard to design a radio front end in software...

A single antenna with good gain across a wide range of frequencies.


9 levels of CR functionality


How Does a Cognitive Radio Get So Smart?

External Intelligence Sources

OrientEstablish Priority

PlanNormal

Generate Alternatives(Program Generation)Evaluate Alternatives

Register to Current Time

DecideAlternate Resources

Initiate Process(es)(Isochronism Is Key)

Act

Learn

Save Global States

Set DisplaySend a Message

ObserveReceive a Message

Read Buttons

OutsideWorld

NewStates

The Cognition Cycle

PriorStates

Pre-process

Parse

ImmediateUrgent

Infer on Context Hierarchy

OBSERVE-ORIENT-DECIDE-ACT

OODA loop


SPECTRUM SENSING

Goal: Reliably detect presence of a Primary UserDifferent Primary Users have different sensitivity thresholdsThree possible approaches:1. Matched Filter2. Energy detector3. Cyclostationary Feature detectorLocal Spectrum Sensing– Each user makes decision on a Primary User presence based on its local sensing measurementsCooperative Spectrum Sensing


Outline

Introduction

Software-defined radio-Cognitive Radio

StandardizationResearch Issues

References


Standardization efforts

IEEE 802.22 WRAN

SDR Forum

GNU Radio Project

DARPA xG

JTRS

North R., Browne N., Schiavone L., Joint Tactical Radio System- Connecting the GIG to the tactical Edge, MILCOM 2006, 23-25 Oct, 2006, Washington, DC. USA.


TThe Vanu Software Radio GSM he Vanu Software Radio GSM Base StationBase Station from Vanu can support multiple cellular technologies and frequencies at the same time and can be modified in the future without any hardware changes.

GSM + CDMA waveforms

Written in C++, running under the Linux OS.

FCC approves first software-defined radio...2004

IEEE Spectrum, January 2007


Challenges and Research Issues

Hardware

Learning Mechanisms

Routing and Upper layer Issues (Networking, QoS)

Developing spectrum sharing behaviors

Sensitive detection

Frequency assignment negotiation

Resource allocation

Security (Unintentional config..)

Integration with “spectrum market”


• Optimize transmission parameters

• Adapt rates through feedback

• Negotiate or opportunistically use resources

Physical Layer

MAC Layer

Network Layer

Transport Layer

Application Layer

OFDM transmissionSpectrum monitoring

Dynamic frequency selection,

modulation, power control

Analog impairments compensation

Routing, System Management, QoS and other upper layer issues...

Cross-layer design


Some SDR platforms


Outline



Standardization




What about satellites!!!

Satellite knowledge chunk in Mitola’s book (2000)

Software Radio in Space Segment by Catherine Morlet, European Space Agency (ESA), 2006.

How can satellites take role in the game?Or can they?


WAND (softWare rAdio techNology in space segment stuDy)

Software Radio in Space Segment Final Report v1.1

20 April 2006

Alcatel Alenia Space France (FR)

Alcatel Alenia Space Espana (SP)

Atos Origin (SP)

Carlo Gavazzi (IT)

The introduction of Software Radio Technology at the satellite level has particular interest for:

• Improving the functionalities of a payload/repeater. • Introducing standard updates. • Modifying the mission of a payload/repeater. • Introducing new concepts (e.g. adaptative coding and modulation).


Satellite Lifetime ~ 10-15 years

Standards and associated algorithms are going to evolution during this period putting the satellite in risk of obsolescence during its lifetime period.


Other issues

Intelligence in satellite

Spectrum Manager(!) Can it be logical?

Policy Updates by satellites (Broadcasts)


Simulation Scenario

A 1000 m X 1000 m areaSome WLAN users Some SUs (mobile)

High Altitude Platform decides on frequency and other transmission parameters based on feed-back from the SUs and the policies from LEO or Command Center.


Performance Evaluation

Effect of number of SUs

Overall Throughput

SU Throughput

Interference by SUs

Spectrum Utilization

RESULTS COMING SOON!


To conclude...

More efficient use of spectrum (may decrease cost of the services like GSM calls)

Flexibility (Interoperability)

Dreaming of a universal device!


References

S. Haykin, "Cognitive radio: brain-empowered wireless communications," IEEE Journal Selected Areas in Communications, vol. 23, no. 2, pp. 201 - 220, 2005. J. Mitola III, “Software radios survey, critical evaluation and future directions,” IEEE AES Systems Magazine, Vol. 8, No. 4, pp. 25-36, Apr. 1993.I.F. Akyıldız, W-Y.Lee, M.C. Vuran, S.Mohanty,”NeXt generation/dynamic spectrum access/cognitive radio wireless networks: A survey”, Computer Networks Journal (Elsevier), vol. 50, pp. 2127-2159, September 2006. David Scaperoth, Cognitive Software Defined Radio: Applications of Cognitive SDR using the GNU Radio and the USRP, 09/09/05.http://www.cognitiveradio.wireless.vt.edu/dokuwiki/doku.php?id=research:radio_hw_swhttp://web.syr.edu/~ejhumphr/http://bwrc.eecs.berkeley.edu/Research/Cognitive/publications.htmNeli Hayes, JTRS Specification: The past, the present, and the future..., MILCOM 2005.J. Powell, “Public safety perspectives on cognitive radio–Potential and pitfalls,” presented at the Conf. Cognitive Radios, Technology Training Corporation, Las Vegas, NV, Mar. 15–16, 2004.J. D. Shilling, “FCC rulemaking proceeding on cognitive radio technologies,” presented at the Conf. Cogn. Radios, Technol. Training Corp., Las Vegas, NV, Mar. 15–16, 2004.IEEE Spectrum, January 2007.

http://web.syr.edu/~ejhumphr/

http://bwrc.eecs.berkeley.edu/Research/Cognitive/publications.htm


Thank You!Questions?

[email protected]

www.satlab.cmpe.boun.edu.tr

mailto:[email protected]

http://www.satlab.cmpe.boun.edu.tr/

next generation wireless networks: smart radios

Documents

radio spectrum

spectrum holea spectrum

spectrum occupancy

allocated spectrum

term cognitive radio

certain spectrum band

radiorelated domains

user requirements