Wireless Access Graduate course in Communications Engineering - - PowerPoint PPT Presentation

Wireless Access

Graduate course in Communications Engineering University of Rome La Sapienza Rome, Italy 2020-2021

Lecture 5 – November 2, 2020

Cognitive radio and networks

Outline What is Cognitive Radio and why using it Regulation of Cognitive Radio Cognitive radio in 5G networks

What is Cognitive Radio?

A Cognitive Radio “is a radio frequency transmitter/receiver that is designed to intelligently detect whether a particular segment of the radio spectrum is currently in use, and to jump into (and out of, if necessary) the temporarily-unused spectrum very rapidly, without interfering with the transmission of other authorized users”

The term “Cognitive Radio” was coined by Joseph Mitola in an article published in 1999

Ref: J. Mitola et al., “Cognitive radio: Making software radios more personal,” IEEE Pers. Commun.,

• vol. 6, no. 4, Aug. 1999

What is Cognitive Radio A Cognitive Radio “is self-aware, user-aware, RF-aware, and incorporates elements of language technology and machine vision”

The concept of a Radio capable of adapting to the environment and

• f adjusting transmission parameters according to internal and

external unpredictable events is very appealing in the wireless world

The final goal remains to form wireless networks that cooperatively coexist with other wireless networks and devices What is Cognitive Radio

Cognitive Radio External Stimuli E x t e r n a l S t i m u l i

A Cognitive Radio can be defined as a wireless system that is aware

• f

the surrounding environment By sensing the outside world, a Cognitive Radio learns from the environment and adapts its behaviour accordingly

What is Cognitive Radio

Standard Radio Cognitive Radio

Awareness Learning I n t e l l i g e n c e Efficiency R e l i a b i l i t y R e c

• n

f i g u r a b i l i t y

What is Cognitive Radio

OBSERVE PLAN DECIDE LEARN ACT

Cognitive Radios are aware of their surrounding environment Cognitive Radios evaluate among several strategies Cognitive Radios are always capable to select one strategy of operation Cognitive Radios can enrich experience by forming new strategies Cognitive Radios perform communication according to the selected strategy

A Cognitive Radio behaves according to five main actions:

What is Cognitive Radio

Spectrum access, spectrum efficiency, and spectrum reliability have become critical policy issues during the last years.

Increasing growth of wireless services (3G cellular systems, Wi-Fi, Wireless Internet…) Growing demand for spectrum-based communication links (businesses, consumers, government…) Approval of unlicensed wireless transmissions (UWB) and LTE-U

What is Cognitive Radio

In May 2003, the FCC recognizes Cognitive Radio as a way to dramatically improve the efficiency of spectrum use

Ref: FCC, NOTICE OF PROPOSED RULE MAKING AND ORDER In the Matter of

Facilitating Opportunities for Flexible, Efficient, and Reliable Spectrum Use Employing Cognitive Radio Technologies, ET Docket No. 03-108, December 30, 2003

Advances in technology are creating the potential for radio systems to use spectrum more intensively and more efficiently than in the past Cognitive radio technologies have the potential to provide a number

• f benefits that would result in increased access to spectrum and

also make new and improved communication services available to the public.

Regulation of Cognitive Radio

1

Licensed Networks

Cognitive Base Station

Example: Cognitive Cellular Networks

A licensee employs cognitive radio technologies internally within its own network to increase efficiency of use of the radio resource

Cognitive Base Station

Dynamic Frequency Selection Adaptive Modulation Transmit Power Control

In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios

Regulation of Cognitive Radio

2

Secondary Markets

A licensee and third party sign an agreement allowing secondary spectrum uses for cognitive radio devices

Example: Public Safety Leasing Primary Network

Headquarter

S e c

• n

d a r y N e t w

• r

k

• f

C

• g

n i t i v e D e v i c e s

Cognitive devices

• perate on the

channels that are designated as available by the licensee and avoid

• peration on any
• ther frequency

The public safety licensee may reclaim access to its licensed spectrum at any time

In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios

Regulation of Cognitive Radio

3

Coordination

• f Licensed

Operation

Multiple licensed services can operate in the same frequency bands by coordinating their use to avoid mutual interference Example: Coexisting Networks N e t w

• r

k A N e t w

• r

k B

Devices in the two networks gather information about spectrum utilization and perform an automated waveform selection

In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios

Regulation of Cognitive Radio

4

Non-voluntary third party access

Unlicensed Cognitive devices operate at times and locations where licensed spectrum is not in use

Example: Rural Markets & Unlicensed Devices

TV Station

Urban Area Rural Area

Low-Power unlicensed

• peration (under Part 15

limit) High-Power unlicensed

• peration (above Part 15

limit) In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios

Regulation of Cognitive Radio

CR and coexistence: towards a new communication paradigm

• Modelling and designing the access might not be

limited to managing and controlling the resource within a network

• Future wireless networks will include the

possibility of coordinating access among different systems based on the coexistence paradigm

– We refer to both intra and inter-system coexistence

• Coexistence will introduce completely new

features and structures within both terminals and network agents

Cognitive radio and coexistence: the ISM band

• The problem of spectrum sharing has been (partially)

addressed for wireless systems working in the Industrial Scientific and Medical (ISM) band See lecture on interference

• Systems working in this band include:

– 802.11 (WiFi) – 802.15.1 (Bluetooth) – 802.15.3

• Older systems (WiFi, Bluetooth) do not

define any technique for coexistence and thus they interfere with one another

• When 802.15.4a was defined (2007) techniques for DAA

(Detect And Avoid) were imposed

frequency

PSD 0.9GHz 1.8GHz 2.4GHz 5GHz UWB

GSM UMTS 802.11b/g Bluetooth 802.11a

Given their ultra wide bandwidth, Ultra Wide Band (UWB) radio signals must in principle coexist with other radio signals. T h e c a s e s t u d y

• f

a s i g n a l

• c

c u p y i n g . . . . 7 G H z ! ! ! ! !

Cognitive Radio and coexistence: the Ultra Wide Band case

Recent advances in regulation

• Digital dividend: the benefit deriving from the switch
• ff of analogue TV broadcasting signals in favour of

digital, and the consequent release of radio spectrum

• Spectrum resulting from digital dividend can be

allocated to new broadband services

• Example: Italy

– Frequencies available in the 800, 1800, 2000 and 2600 MHz were assigned in a public bid in September 2011 – Total income: 3.2 billion € – Frequencies were allocated based on a exclusive rights approach with a caveat: sharing based on cognitive radio can be allowed by a future regulation

• What about frequencies reserved to Digital Terrestrial

Television?...TV White Spaces

Recent advances in regulation

• FCC frees up vacant TV airwaves for “Super Wi-Fi”

technologies (September 2010)

• Example of scenario #4 (Non-voluntary third party access)

• Access to TV Bands is granted based on the geographical

position of the cognitive device

• Each cognitive device must satisfy the following

requirements:

1. Geo-location capability with positioning error < 50 m 2. Internet access capability

• A cognitive device will adopt the following procedure

before starting transmission:

1. Determine its own position (at switch-on time and then every 60 seconds) 2. Connect to a remote database and download list of available (that is: not used) TV channels (every 48 hours or every time its position changes by more than 100 m) 3. Select an available channel and start transmitting

• Note: Spectrum sensing is not mandatory

FCC rules for TV white spaces access

• Discussion on TV White Spaces has been ongoing for a while in Europe
• Initial studies suggested that White Spaces are potentially numerous across

Europe:

TV White Spaces in Europe

• European Conference of Postal and Telecommunications Administrations

(CEPT) Group SE43 has been working towards a regulation for White Spaces:

• ECC Report 159 on Technical and operational requirements for the operation of

cognitive radio systems in the band 470-790 MHz published by CEPT Group SE43 in January 2011

TV White Spaces in Europe

• ECC Report 159 was complemented by ECC Report 186, released in

January 2013

• ECC Report 186 defines technical and operational requirements for the
• peration of white space devices under the geolocation approach
• ECC reports define a Master/Slave approach in the operation of White

Space Devices:

• A Master WSD has the capability of accessing a geolocation database

in order to receive a list of available channels for its geographical position

• Slave WSDs do not have the above capability, and rely on a Master

WSD to provide them the information obtained by a geolocation database

• Topics addressed in report 186 include:
• Considerations on location accuracy
• WSD requirements
• Database management
• Information language for exchanging geolocation database info
• Combined sensing and geolocation

• OFCOM (the regulation entity for UK) is well ahead in the regulation and

deployment of communication networks in White Spaces

• July 2009: First OFCOM statement on usage of TV White Spaces
• September 2011: OFCOM decides to allow cognitive usage of White Spaces
• based on the geolocation database approach
• devices originally expected to be allowed to operate by 2013, eventually

started by the end of 2015

TV White Spaces in Europe UK

• Field tests were carried out before allowing operation of WSD devices
• Tests started in November 2013, and concluded in 2015

TV White Spaces in Europe UK

• Trial setups open to customers are currently active in Scotland, Wales and rural

England

• The setups typically provide 30 Mb/s where landline connections used to

provide 1-2 Mb/s

• DTV frequency planning in all EU countries should comply with the outcome of

the Geneva 2006 ITU Regional Radiocommunication Conference, the latest ITU revision on the assignment of frequencies in the TV bands to each country BUT…

TV White Spaces in Italy

1. Ignore, at least in some cases, the Geneva ‘06 agreement, using frequencies not assigned to Italy 2. Adopt an extremely dense frequency planning scheme, based on the concept of Single Frequency Network (SFN), taking advantage of OFDM robustness to multipath

• Italy has peculiar characteristics in terms of TV

frequencies allocation

• An extremely large number of local TV stations led in

fact to the decision of:

2) TV White Spaces are extremely scarce in Italy

TV White Spaces in Italy

– It is expected that most of opportunistic data communications over TV bands in Italy will take place in so-called TV Gray Spaces – Gray Spaces are frequencies/channels formally

• ccupied by TV but with very weak signal

– Gray Spaces are of course more probable to be available indoor… As a result: 1) Italy had longstanding interference issues with neighbouring countries, only recently addressed by compensating TV stations near the border to convince them to switch frequencies… About 50 M€ of compensation money so far

Drawn from: L. Bedogni, F. Malabocchia, M. Di Felice, and L. Bononi, “Indoor Use of Gray and White Spaces - Another Look at Wireless Indoor Communication,” IEEE Vehicular Technology Magazine, Vol. 12, No. 1, March 2017, pp. 63 -71.

• Cognitive radios determine the availability of TV White Spaces by

accessing external databases and (optionally) by observation of RF spectrum (spectrum sensing)

Cognitive radio: untapped potential

• Definitely a step forward, but… the original cognitive radio concept

was a much wider acception

• In 5G the cognitive radio vision can be fully embodied

DTV1 coverage area Channels: 22, 31, 39 DTV2 coverage area Channels: 25, 29, 40 CR coverage area Available TVWS Channels: 22, 25, 29, 31, 39, 40 Maximum allowable transmit power: 0.1 W , 4W , 4W , 0.5 W , 4 W , 0.2 W

5G: faster, better, smarter

• Application scenarios foreseen for 5G networks all

share a common set of requirements:

– Flexibility at physical layer – Intelligence in devices – Intelligence in network planning, organization and cooperation

• Bottom line: 5G devices and networks will need to be

smart

• Cognitive radio was introduced in order to be smarter

in the use of the radio spectrum -> perfect match for 5G!

• Cognitive radio is more than mere observation and reaction: it adds

awareness on device, network and outside world

• Awareness should be taken advantage of by:

– devising new strategies for efficient access to the radio resource – analyze the impact of such strategies on Quality of Service and Quality of Experience perceived by users – revise and improve strategies accordingly to the analysis

Cognitive radio and 5G: putting intelligence in the network

• A cognitive decision engine is the core element in cognitive radios

and networks

• It provides the intelligence to take decisions based on awareness of

the outside world

• The cognitive decision engine can play a key role in 5G

CR in 5G: interface/network selection in 5G

5G devices will most often face a strategic choice both at start-up and during

• peration: which wireless interfaces vs. networks should be used?

5G Cognitive Decision Engine

Drawn from: R. Trestian, O. Ormond and G.-M. Muntean, “Game Theory-Based Network Selection: Solutions and Challenges,” IEEE Communications Surveys & Tutorials, Vol. 14,

• No. 4, Fourth Quarter 2012, pp. 1212 -1231.

CR in 5G: network coexistence and cooperation

• 5G will lead to densification at two levels:

– Intra-network: many devices within a network – Inter-network: many networks in the same geographic area

• Inter-network coexistence will be a key feature
• Coexistence may or may not rely on cooperation between

networks

• Cognitive radio can provide the tools to achieve coexistence in

both cases – Coexistence without cooperation: spectrum sensing – Coexistence with cooperation: data exchange, either explicit

• r by means of databases

Context awareness for 5G by cognitive radio: the C-MIANS platform

• the C-MIANS platform integrates cognitive radio features by

merging 3GPP and IEEE standards for context-aware dynamic network selection: – The 3GPP Access Network Discovery and Selection Function (ANDSF) – The IEEE Media-Independent Handover (MIH) – The IEEE 1900.6 standard for cooperative spectrum sensing

• G. Caso, L. De Nardis and M.-G. Di Benedetto, "Toward Context-Aware Dynamic Spectrum Management for

5G," IEEE Wireless Communications, Special Issue on Dynamic Spectrum Access for 5G, to appear October 2017.

Network density in 5G

• DSA and spectrum sharing in 5G call for intranetwork and

internetwork interference control.

• C-MIANS introduces CR, supported by spectrum sensing, as

the approach for dynamic interference control