Lecture 5 October 17, Wireless Access. Graduate course in Communications Engineering. University of Rome La Sapienza. Rome, Italy

Transcription

1 Lecture 5 October 17, 2018 Wireless Access Graduate course in Communications Engineering University of Rome La Sapienza Rome, Italy

2 Cognitive radio and networks

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

4 What is Cognitive Radio The term Cognitive Radio was coined by Joseph Mitola in an article published in 1999 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 A Cognitive Radio is self-aware, user-aware, RF-aware, and that incorporates elements of language technology and machine vision Ref: J. Mitola et al., Cognitive radio: Making software radios more personal, IEEE Pers. Commun., vol. 6, no. 4, Aug. 1999

5 What is Cognitive Radio The concept of a Radio capable of adapting to the environment and of 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

6 What is Cognitive Radio A Cognitive Radio can be defined as a wireless system that is aware of the surrounding environment By sensing the outside world, a Cognitive Radio learns from the environment and adapts its behaviour accordingly Cognitive Radio

7 What is Cognitive Radio Learning Cognitive Standard Radio

8 What is Cognitive Radio A Cognitive Radio behaves according to five main actions: OBSERVE PLAN Cognitive Radios are aware of their surrounding environment Cognitive Radios evaluate among several strategies DECIDE LEARN Cognitive Radios are always capable to select one strategy of operation Cognitive Radios can enrich experience by forming new strategies ACT Cognitive Radios perform communication according to the selected strategy

9 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

10 Regulation of Cognitive Radio In May 2003, the FCC recognizes Cognitive Radio as a way to dramatically improve the efficiency of spectrum use 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 of benefits that would result in increased access to spectrum and also make new and improved communication services available to the public. 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 , December 30, 2003

11 Regulation of Cognitive Radio In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios 1 Licensed Networks Example: Cognitive Cellular Networks Cognitive Base Station A licensee employs cognitive radio technologies internally within its own network to increase efficiency of use of the radio resource Cognitive Base Station Adaptive Modulation Dynamic Frequency Selection Transmit Power Control

12 Regulation of Cognitive Radio In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios 2 Secondary Markets Example: Public Safety Leasing Cognitive devices operate on the channels that are designated as available by the licensee and avoid operation on any other frequency A licensee and third party sign an agreement allowing secondary spectrum uses for cognitive radio devices Primary Network Headquarter The public safety licensee may reclaim access to its licensed spectrum at any time

13 Regulation of Cognitive Radio In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios 3 Coordination of Licensed Operation Example: Coexisting Networks Multiple licensed services can operate in the same frequency bands by coordinating their use to avoid mutual interference Devices in the two networks gather information about spectrum utilization and perform an automated waveform selection

14 Regulation of Cognitive Radio In the 2003 document, the FCC identifies four possible scenarios for Cognitive Radios 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 Rural Area Urban Area High-Power unlicensed operation (above Part 15 limit) Low-Power unlicensed operation (under Part 15 limit) TV Station

15 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

16 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 Systems working in this band include: (WiFi) (Bluetooth) Older systems (WiFi, Bluetooth) do not define any technique for coexistence and thus they interfere with one another When a was defined (2007) techniques for DAA were imposed

17 Cognitive Radio and coexistence: the Ultra Wide Band case Given their ultra wide bandwidth, Ultra Wide Band (UWB) radio signals must in principle coexist with other radio signals. PSD GSM UMTS b/g Bluetooth a UWB 0.9GHz 1.8GHz 2.4GHz 5GHz frequency

18 Recent advances in regulation Digital dividend: the benefit deriving from the switch off 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

19 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)

20 FCC rules for TV white spaces 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

21 TV White Spaces in Europe Discussion on TV White Spaces has been ongoing for a while in Europe Initial studies suggested that White Spaces are potentially numerous across 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 MHz published by CEPT Group SE43 in January 2011

22 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 operation 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

23 TV White Spaces in Europe UK 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

24 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 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

25 TV White Spaces in Italy 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 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: 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

26 TV White Spaces in Italy 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 2) TV White Spaces are extremely scarce 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 occupied by TV but with very weak signal Gray Spaces are of course more probable to be available indoor 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

27 Cognitive radio: untapped potential Cognitive radios determine the availability of TV White Spaces by accessing external databases and (optionally) by observation of RF spectrum (spectrum sensing) DTV1 coverage area Channels: 22, 31, 39 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 DTV2 coverage area Channels: 25, 29, 40 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

28 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!

29 Cognitive radio and 5G: putting intelligence in the network 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 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

30 CR in 5G: interface/network selection in 5G 5G devices will most often face a strategic choice both at start-up and during operation: which wireless interfaces vs. networks should be used? 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 G Cognitive Decision Engine

31 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 or by means of databases

32 Context awareness for 5G by cognitive radio: the C-MIANS platform 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 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 standard for cooperative spectrum sensing

33 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