Enhancement of Spectrum Utilization in Non Contiguous DSA

Enhancement of Spectrum Utilization in Non. Contiguous DSA with Online Defragmentation Suman Bhunia, Vahid Behzadan and Shamik Sengupta Supported by NSF CAREER grant CNS #1346600

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 2

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Why Dynamic Spectrum Access? MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 3

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Non-Contiguous DSA Ø Dynamic RF environment – Dynamic spectrum requirement – Sometimes single spectrum opportunities are not adequate to support users’ requirements ØAllocation of spectrum in the form of non-contiguous blocks MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 4

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 5

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation NC-DSA ØPUs have priority in spectrum acquirement ØSUs (red, green and blue) change their spectrum with PU activity ØIncreases fragments ØOverhead due to guard bands (yellow) ØDefragmentation minimizes the spectrum wastage MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 6

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Problem Statement ØSinc type pulses lead to large sidelobes - out of band transmission ØGuard bands to protect fragments ØOpportunistic NC spectrum allocation increases number of spectrum fragments ØIncreasing fragments increase spectrum wastage by guard bands ØThis paper investigates – The cost of wastage due to guard bands – Overhead of coordination in NC DSA – Mitigation techniques ØProposes Online Spectrum Defragmentation as an effective solution to wastage of spectrum due to guard bands. 7 S Bhunia, V Behzadan, S Sengupta MILCOM 2015

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 8

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Some related works Ø Aggregation Aware Spectrum Assignment (AASA) 1 – All users require the same amount of spectrum – Uses first-fit approach for channel assignments Ø Maximum Satisfactory Algorithm (MSA) 2 – users may have different spectrum requirements – Uses best-fit algorithm Ø Channel Characteristic Aware Spectrum Aggregation algorithm (CCASA) 3 – Considers the heterogeneity of data carrying capacity in spectrum – Uses sliding window method 1) D. Chen, Q. Zhang, and W. Jia, “Aggregation aware spectrum assignment in cognitive ad-hoc 2) 3) networks, ” in 3 rd International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2008. Crown. Com 2008, pp. 1– 6, IEEE, 2008. F. Huang, W. Wang, H. Luo, G. Yu, and Z. Zhang, “Prediction based spectrum aggregation with hardware limitation in cognitive radio networks, ” in IEEE 71 st Vehicular Technology Conference (VTC 2010 -Spring), 2010, pp. 1– 5, IEEE, 2010. J. Lin, L. Shen, N. Bao, B. Su, Z. Deng, and D. Wang, “Channel characteristic aware spectrum aggregation algorithm in cognitive radio networks, ” in IEEE 36 th Conference on Local Computer Networks (LCN), 2011, pp. 634– 639, IEEE, 2011. MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 9

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Related Works… Ø Jello: A MAC Overlay for Dynamic Spectrum Sharing 1 – Distributed NC OFDM prototype – Distributed defragmentation triggered by other SU departure – Limited sensing window – Homogenous spectrum 1) L. Yang, W. Hou, L. Cao, B. Y. Zhao, and H. Zheng, “Supporting demanding wireless applications with frequency-agile radios. , ” in Pro- ceedings of the 7 th USENIX Conference on Networked Systems Design and Implementation, NSDI 2010, pp. 65– 80, 2010. MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 10

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 11

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Problem Formulaion ØData Rate matrix ØSpectrum assignment matrix: ØDefine three (N×C) matrices: – Data-subcarrier assignment matrix (D) – Pilot-subcarrier assignment matrix (P) – Guard-subcarrier assignment matrix (G) MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 12

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Problem Formulaion… ØThroughput achieved: ØCross Channel Interference Matrix: ØConstraint for interference: MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 13

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Optimization Problem Interference Demand satisfaction Prevent overlapping Transmission BW Power consumption Interface limitation MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 14

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Theorem: The throughput maximization problem is NP-hard even if there is no PU present. ØAssume – No cross channel interference – Each subcarrier provides same data rate – SUs have different data rate demand – An SU can be allocated with spectrum iff its demand is met ØThe goal is to maximize total throughput of the system Øreduction of the 0 -1 knap sack problem MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 15

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 16

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Centralized Spectrum Allocation ØCentral controller supervises the spectrum allocation ØUses dedicated out-of-band common control channel (CCC) ØSUs periodically sense the spectrum and send the spectrum usage map to the controller ØSU also notifies the controller of its throughput requirements ØController has two states: – Steady state – Arrangement state MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 17

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Centralized Spectrum Allocation MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 18

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Distributed Method MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 19

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Semi Centralized Method MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 20

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 21

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Prototype Schema ØGNURadio controlled USRP Ø 200 KHz band Ø 256 subcarriers of 781. 25 Hz Øminimum of 28 subcarriers ØFiltering and windowing – degrade OFDM signal, not agile enough ØUnutilized subcarriers are required as guard bands MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 22

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Spectrum Usage NC spectrum allocation of A: Received Signal NC spectrum allocation of B : MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 23

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 24

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Simulation Parameters MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 25

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Simulation Results ØThroughput obtained for the network Øcompare with CCASA ØCCSA does not consider the waste of spectrum Øthroughput increases linearly until a saturation point MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 26

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Simulation Results Ø MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 27

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Simulation Results ØThroughput achieved for the entire network ØSignificantly better performance in comparison with Jello ØWith high no. of nodes, the throughput of decentralized method decreases MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 28

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Outline ØIntroduction ØMotivation ØSome Related Work ØProposed Model ØAlgorithms ØPrototype ØPerformance Evaluation ØConclusion and Future Work MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 29

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Conclusion ØOnline Defragmentation is proposed as a method of increasing spectrum utilization ØEfficiency of this method was investigated in three different network scenarios: – Infrastructure – Distributed – Semi-centralized. Øproof-of-concept prototype ØRegardless of scenario, defragmentation provides better performance MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 30

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Future Works ØComplete implementation of the proposed algorithms in testbed ØOptimization of guard bandwidth ØHeterogeneity of subcarriers ØAdaptive defragmentation based on spatial considerations MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 31

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Thank You! MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 32

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation Appendix MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 33

Enhancement of Spectrum Utilization in Non-Contiguous DSA with Online Defragmentation MILCOM 2015 S Bhunia, V Behzadan, S Sengupta 34