Spectrum Management and Cognitive Radios Alessandro Guidotti, XXIV ciclo

Transcription

1 Bologna, 24-25/01/2012 Spectrum Management and Cognitive Radios Alessandro Guidotti, XXIV ciclo DEIS Fondazione Ugo Bordoni

2 Is spectrum lacking? Command & Control spectrum allocation model Static spectrum allocation Ever increasing demand for new wireless services Broadband access to anyone, anywhere, at anytime Commonly shared feeling of spectrum scarcity Great amount of underused resources

3 Is spectrum lacking? Two main approaches to this issue Flexible spectrum access Cognitive Radios Release of spectrum bands thanks to more efficient wireless technologies Digital swtich-on process (DVB-T)

4 My Ph. D. activity Spectrum Management & Cognitive Radios Cognitive Radios Spectrum Release CEPT SE43 Amount of spectrum potentially available as White Space Geolocation databases Mutual interference between DVB-T and LTE Introduction of broadband services in the 800 MHz band CEPT CPG PT-D Characterization of the Hidden Node Margin Coexistence between CRs and TETRA Cooperative energy detection algorithms FP7 Project Cognitive Satellite Terrestrial Radios SUPELEC Stochastic Geometry for network interference characterization

5 Network interference Modeling of network interference is a key issue in next-generation systems Interference mitigation, control of e.m. emissions, etc. CRs: network performance, harmful interference control Three main factors 1. Spatial distribution of the nodes 2. Transmission characteristics 3. Propagation characteristics

6 Spatial distribution Deterministic model Known locations Locations constrained to fixed structures (e.g., hexagonal grid) Cognitive Radio networks Inherent unplanned, irregular and random distribution No deterministic approach Extensive and complex system-level simulations Advanced mathematical tools for statistical modeling Spatial average performance metrics

7 Stochastic Geometry Network: snapshot of a stationary random model in the Euclidean space Nodes locations: realization of a Point Process d-dimensional Euclidean space set S of all the possible sequences of points in it, s.t. any Φ in S is finite and simple PP: r.v. whose values are the point patterns Φ taken from S

8 Y [m] Poisson Point Process The homogeneous PPP is the most used model Number of nodes: Poisson r.v. Locations: uniformly distributed X [m] Spatial invariance properties Superposition, thinning, mapping Slivnyak s Theorem: removing a point does not change the distribution of the other points

9 Interference as PPP Exponential power-decaying path-loss model, α>2 Objective: closed-form of the MGF in b(o,r 1,R 2 ) Coverage probability, average downlink rate, ASEP Previous works: closed-form in b(o,r) with Rayleigh fading only, no modulation

10 Moment Generating Function Procedure Condition on having k nodes The single interference terms are i.i.d. Solve the expectations on modulation and node activity Decondition on having k nodes Restrict integration bounds to b(o,r 1,R 2 )

11 Moment Generating Function Generalized modulation coefficients, nodes activity and network layout

12 Moment Generating Function Series expansion of Γ(a,x) and Hypergeometric functions: Nakagami-m fading channels Rayleigh fading

13 Moment Generating Function α=4 Nakagami-m, m 0 =2 α=5 Rayleigh Lower values for decreasing α Lower values for increasing p, λ Slight dependence on the channel model

14 Average downlink rate BSs distributed according to homogeneous PPP in R d with density λ The intended node (y o) communicates with the closest BS, all the other BSs act as interferers Previous works: three-fold integral expression with Rayleigh fading and α=4

15 Average downlink rate Proposed model: MGF-based approach Rate: function of the MGF of the aggregate interference and the intended link fading

16 Average downlink rate Meijer-G function properties Single-integral with Meijer-G function Generalized fading channels Different channel models on intended and interfering links

17 Average downlink rate Nakagami-m fading Lognormal fading Hermite polynomials

18 Average downlink rate Nakagami-m vs Rayleigh, m 0 =2 α=4 α=5 Rayleigh The rate significantly improves for higher α Slight improvements for increasing m 0 (Rayleigh)

19 Results Coverage Single-integral, Rayleigh, α=4 closed-form, generalized fading, α>2 Average downlink rate Three-fold integral, Rayleigh, α=4 single-integral, generalized fading, α>2 Average Symbol Error Probability Semi-analytical model single-integral Synchronous case upper bounds the asynchronous Many parameters of interest in closed-form

20 Future works MIMO systems Statistical characterization of uncorrelated paths Cooperative sensing Theoretical expression with generalized fading Relay networks Effect of multi-hop communications Cognitive Satellite networks Aggregate interference at Ground Stations

21 International activities CEPT CPG PT-D WRC-12 agenda items 1.5, 1.7, 1.8, 1.17, 1.18, 1.20, and 1.25 CEPT SE43 Technical and operational requirements for the operation of cognitive radio systems in the white spaces of the frequency band MHz CoRaSat (FP7) Cognitive Radio for Satellite Communications Cost Action IC0902 Cognitive Radio and Networking for Cooperative Coexistence of Heterogeneous Wireless Networks

22 Personal contributions A. Guidotti, M. Di Renzo, G. E. Corazza, and F. Santucci, Simplified Expression of Coverage Probability and Average Rate of Cellular Networks Using Stochastic Geometry, IEEE Transactions on Communications (to be submitted), 2012 A. Guidotti, M. Di Renzo, G. E. Corazza, and F. Santucci, Simplified Expression of the Average Rate of Cellular Networks Using Stochastic Geometry, IEEE International Conference on Communication 2012 (ICC 2012), June 2012 C. Merola, A. Guidotti, M. Di Renzo, F. Santucci, and G. E. Corazza, Average Symbol Error Probability in the Presence of Network Interference and Noise, IEEE International Conference on Communication 2012 (ICC 2012), June 2012 A. Guidotti, D. Guiducci, M. Barbiroli, C. Carciofi, P. Grazioso, and G. Riva, Coexistence and Mutual Interference between Mobile and Broadcasting Systems, IEEE Vehicular Technology Conference - Spring 2011 (VTC Spring 2011), May 2011 A. Guidotti, P. Grazioso, M. Barbiroli, C. Carciofi, D. Guiducci, and G. Riva, Analysis of coexistence and mutual interference between mobile and digital television systems, Systemas y Telematica (S&T), October 2010 M. Barbiroli, A. Guidotti, P. Grazioso, and G. Riva, Coexistence and mutual interference between mobile radio and broadcast systems Preliminary simulation results, COST 2100 TD(09)709, February 2009 WRC-12 AI Broadcasting versus mobile: theoretical analysis of mutual interference, Tech. Rep. CPGPTD(10)109, Italian Contribution to CPG PT-D - Agenda Item 1.17, Aug WRC-12 AI Options for method A1, Tech. Rep. CPGPTD(10)156, Italian Contribution to CPG PT-D - Agenda Item 1.17, Aug WRC-12 AI Options for method A1, Tech. Rep. CPGPTD(11)33, Italian Contribution to CPG PT-D - Agenda Item 1.17, Aug M. Barbiroli, C. Carciofi, D. Guiducci, A. Guidotti, E. Tarantino, and G. Riva, Advantages and disadvantages of the introduction of IMT systems in the 800 MHz band, International Conference on Electromagnetics in Advanced Applications 2011 (ICEAA 2011), September 2010

23 Personal contributions Availability of spectrum for white space devices in the band MHz, Tech. Rep. SE43(10)22, Italian Contribution to CEPT SE43, Jan Calculation of the Hidden Node Margin in a real Italian scenario, Tech. Rep. SE43(10)123, Italian Contribution to CEPT SE43, Aug M. Barbiroli, C. Carciofi, A. Guidotti, and D. Guiducci, Evaluation and Analysis of the Hidden Node Margin for Cognitive Radio System Operation in a Real Scenario, European Conference on Antennas and Propagation 2011 (EuCAP 2011), April 2011 S. Kandeepan, L. De Nardis, M.-G. Di Benedetto, A. Guidotti, and G. E. Corazza, Cognitive Satellite Terrestrial Radios, IEEE Global Communications Conference (GLOBECOM 2010), December 2010 Enforcement issues related to the geolocation database approach, Tech. Rep. SE43(10)96, Italian Contribution to CEPT SE43, Jun Translation of the information provided to the geolocation database into elements of authorisation to the WSD, Tech. Rep. SE43(10)124, Italian Contribution to CEPT SE43, Aug Proposal of an application methodology to combine geo-location database and sensing, Tech. Rep. SE43(11)38, Italian Contribution to CEPT SE43, Jul Performance analysis of cooperative energy detection sensing, Tech. Rep. SE43(11)37, Italian Contribution to CEPT SE43, Jul Feasibility of autonomous operation of WSDs using sensing, Tech. Rep. SE43(11)62, Italian Contribution to CEPT SE43, Sep Consideration of coexistence between WSD and TETRA, Tech. Rep. SE43(11)39, Italian Contribution to CEPT SE43, Jul R. Suffritti, G. E. Corazza, A. Guidotti, V. Petrini, D. Tarchi, A. Vanelli-Coralli, and M. Di Renzo, Cognitive hybrid satellite-terrestrial systems, International Conference on Cognitive Radio and Advanced Spectrum Management 2011 (CogART 2011), October 2011

24 Short courses Long Term Evolution e 4G Compatibilità Elettromagnetica LS Nuove frontiere nella gestione dello spettro radio SatNEx Summer School Newcom++ Spring School Cognitive Wireless Communication Networks COST2100/CONET/Newcom++ Training School Cooperating Objects and Wireless Sensor Networks

25 Thank you!