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UNIVERSITÀDEGLI STUDI DI ROMA<br />“TOR VERGATA”Corso di Dottorato  in Ingegneria delle Telecomunicazioni e Microelettroni...
Summary<br /><ul><li>3GPP and 4G femtocells
Problem statement
Dynamic Frequency Selection Algorithms
Results
Conclusions
Other activities
Publications</li></ul>2<br />
3GPP and 4G femtocell<br /><ul><li>Smallcellular base station (BS) designed for use in a home or small business environment
Works on licensed band(s)
Typically supports 2 to 4 active mobile phones
Allows service providers to extend service coverage indoors
Extends BS to allow a simpler, self-contained deployment
Provides improvements to both coverage and capacity</li></ul>3<br />
DSM and Cognitive radio<br /><ul><li>Dynamic Spectrum Management (DSM) is a set of techniques that is being researched and...
Cognitive radio
The wireless node changes its transmission and/or reception parameters to communicate efficiently
Executes active monitoring of several factors in the external and internal radio environment
Radio frequency spectrum
User behavior
Network state</li></ul>4<br />
Problem statement and proposedsolutions<br />5<br />
Problemstatement<br /><ul><li>Spatially Dense femtocell deployment
High bit-rate nodes
No accurate radio planning is possible
Small number of channels areavailable
Macro-to-femtointerference
can be avoided by allocating separated channels
Interferenceamongfemtocells
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Dynamic frequency allocation in femtocells-based systems: algorithms and performance analysis

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Transcript of "Dynamic frequency allocation in femtocells-based systems: algorithms and performance analysis"

  1. 1. UNIVERSITÀDEGLI STUDI DI ROMA<br />“TOR VERGATA”Corso di Dottorato in Ingegneria delle Telecomunicazioni e Microelettronica<br />“Dynamic frequency allocation in femtocells-based systems: algorithms and performance analysis”<br />Advisor: <br />Prof. Francesco Vatalaro<br />Co Advisor:<br />Prof. Franco Mazzenga<br />Ph. D. candidate: <br />Remo Pomposini<br />
  2. 2. Summary<br /><ul><li>3GPP and 4G femtocells
  3. 3. Problem statement
  4. 4. Dynamic Frequency Selection Algorithms
  5. 5. Results
  6. 6. Conclusions
  7. 7. Other activities
  8. 8. Publications</li></ul>2<br />
  9. 9. 3GPP and 4G femtocell<br /><ul><li>Smallcellular base station (BS) designed for use in a home or small business environment
  10. 10. Works on licensed band(s)
  11. 11. Typically supports 2 to 4 active mobile phones
  12. 12. Allows service providers to extend service coverage indoors
  13. 13. Extends BS to allow a simpler, self-contained deployment
  14. 14. Provides improvements to both coverage and capacity</li></ul>3<br />
  15. 15. DSM and Cognitive radio<br /><ul><li>Dynamic Spectrum Management (DSM) is a set of techniques that is being researched and developed to improve performance of a communication network
  16. 16. Cognitive radio
  17. 17. The wireless node changes its transmission and/or reception parameters to communicate efficiently
  18. 18. Executes active monitoring of several factors in the external and internal radio environment
  19. 19. Radio frequency spectrum
  20. 20. User behavior
  21. 21. Network state</li></ul>4<br />
  22. 22. Problem statement and proposedsolutions<br />5<br />
  23. 23. Problemstatement<br /><ul><li>Spatially Dense femtocell deployment
  24. 24. High bit-rate nodes
  25. 25. No accurate radio planning is possible
  26. 26. Small number of channels areavailable
  27. 27. Macro-to-femtointerference
  28. 28. can be avoided by allocating separated channels
  29. 29. Interferenceamongfemtocells
  30. 30. …even if a dedicated frequency band is allocated to the femtocell network.
  31. 31. harmful in highly dense HNB’s environments!
  32. 32. can compromise the opportunity of enjoying high data rate services.</li></ul>6<br />
  33. 33. Toolsforfemtocellinterferencemitigation<br /><ul><li>Starting from local measurements on:
  34. 34. Noise power
  35. 35. Interference power on different bands
  36. 36. Interference can be reduced by:
  37. 37. Properly controlling the transmitted power (e.g. power control)
  38. 38. Change of femtocell operating frequencies
  39. 39. Idea: available operating frequencies for each femtocell can include all the bands allocated to the (several) mobile operators (e.g. mutual frequency exchange)</li></ul>7<br />
  40. 40. Cognitive Femtocells <br /><ul><li>Allow interaction/coordinationamongfemtocells to maximize the number of activefemtocellsfor a giveninterferenceenvironment
  41. 41. Adoption of algorithms for intelligentfemto-BSs to dynamically set theiroperatingfrequencies
  42. 42. Algorithmsrequirements:
  43. 43. Shallconsider:
  44. 44. CooperatingFemtocells
  45. 45. No cooperationamongfemtocells
  46. 46. Algorithmsshall be simple to implement i.e. nodrasticalchangesto existing standard shall be required
  47. 47. Shall be based on the available data the single femtocell can measure locally</li></ul>8<br />
  48. 48. On the feasibilityof the proposedapproach<br />9<br /><ul><li>Investigation on the actual radio mobile standards to infer on the modifications required in the femtocells in order to implement cognitive features
  49. 49. Two operating modes of the femtocells needs to be considered:
  50. 50. Femtocell startup phase
  51. 51. Femtocell operating cycle (after startup)</li></li></ul><li>Femtocell START-UP procedures<br />10<br />START-UP<br />self-optimizationphase<br /><ul><li>On Start-Up Femtocell
  52. 52. connects to the own operator network
  53. 53. sets its RF parameters
  54. 54. core network assisted
  55. 55. self-setting RF parameters based on monitoring of the radio channels
  56. 56. self-optimization phase
  57. 57. Femtocell dynamically adapt its parameters to the changing environment conditions
  58. 58. Simply to adapt to our scopes</li></li></ul><li>DynamicFrequencySelectionAlgorithms<br /><ul><li>Twodifferentapproachesforfemtocellshavebeenproposed
  59. 59. Greedy DFS algorithm (GDFS):
  60. 60. femtocells are absolutelygreedy and aimtoimmediatelymaximizetheirSignal-to-InterferenceRatio (SIR) carelessofwhichoperatoroffers the lessinterferedchannel
  61. 61. Operator-oriented DFS algorithm (ODFS):
  62. 62. eachfemtocellusesitsown band until the QoSconditionisverified (SIR≥ρ0)
  63. 63. SIR</li></ul>11<br />
  64. 64. DFS algorithms with Power Control<br /><ul><li>Each femtocell perform these tasks:
  65. 65. If SIR > threshold
  66. 66. Decrease Ptx in order to reach the target quality level
  67. 67. Else
  68. 68. Increase Ptx up to Pmax
  69. 69. If Ptx>Pmax
  70. 70. Interference measurement on f1,f2,…,fN
  71. 71. If SIRop> threshold
  72. 72. Select the i-th frequency (belonging to own operator)
  73. 73. Else if SIRext > threshold
  74. 74. Select the j-th frequency (belonging to a different operator)
  75. 75. Else
  76. 76. Sensing mode
  77. 77. Sensing mode: programmed standby feature envisaged in order not to damage the other femtocells.
  78. 78. Since the interference conditions prevent the femtocell from transmitting, it temporarily disables transmission and just performs spectrum sensing.</li></ul>12<br />
  79. 79. Results<br />13<br />
  80. 80. ReferenceScenarios<br /><ul><li>4 network topologies
  81. 81. Random
  82. 82. Regular grid
  83. 83. Perturbedgrid
  84. 84. Building
  85. 85. Maximumtrasmittedpower, Pmax = 20 dBm
  86. 86. DistanceFemtoBS-Terminal, DFBS-Terminal = 4 - 10 m
  87. 87. Outdoor pathlossexponent = 3.2
  88. 88. Indoor pathlossexponent = 2.8
  89. 89. Downlinktransmission direction isconsidered
  90. 90. Greedy data source
  91. 91. SINR threshold : 9,4 dB – 16,4 dB
  92. 92. Carrierfrequency, F = 1800MHz
  93. 93. Band frequencyspacing,Δfc = 10 MHz</li></ul>14<br />
  94. 94. Network topologies 1/2<br />15<br /><ul><li>Random
  95. 95. Femtocells are random distributed in a area of 100 x 100 m2
  96. 96. Regular grid
  97. 97. Baseline for comparing the behavior and performance of DFS algorithms
  98. 98. Perturbed grid
  99. 99. Femtocells are positioned over a regular grid with random 2D displacement around their original point</li></li></ul><li>Network topologies 2/2<br />16<br /><ul><li>Building
  100. 100. 6 floor residential building
  101. 101. Floor area = 200 m2
  102. 102. Floor height = 3 m
  103. 103. Femtocells randomly located inside the apartments
  104. 104. 1 femtocell per apartment
  105. 105. low-medium density scenario
  106. 106. 2 apartments per floor
  107. 107. high density scenario
  108. 108. 4 apartments per floor</li></li></ul><li>Interference<br /><ul><li>Indoor pathloss
  109. 109. Outdoor pathloss
  110. 110. SIR in the case of regular grid topology with optimal frequency assignment</li></ul>17<br />
  111. 111. SIR PDF<br />18<br /><ul><li>Regular grid with optimal frequency assignment
  112. 112. Break of equilibrium
  113. 113. Femtocells simultaneously fall below the threshold
  114. 114. SIR distribution could be approximated as a delta function
  115. 115. Femtocells at the borders spread the SIR distribution
  116. 116. Regular gridrandom network
  117. 117. Larger variance </li></li></ul><li>Average SIR per femtocell<br /><ul><li>Low density scenario
  118. 118. Random topology provide the worst performance
  119. 119. High density scenario
  120. 120. SIR in random topology is slightly better then the SIR in the perturbed grid</li></ul>19<br /><ul><li>DFS algorithms perform better than the initial random assignment
  121. 121. GDFS outperform ODFS due to the greedy nature of femtocells aiming at maximizing their throughput
  122. 122. Random topology (solid line)
  123. 123. Perturbed Grid (dashed line)</li></ul>Average SIR per femtocellishigheruntil the twovaluesof the Poutbecamecomparable<br /><ul><li>With GDFS algorithm the throghput is very near to the optimal curve
  124. 124. Regular Gridwith optimal frequency assignment (solid line)
  125. 125. Regular Grid (dashed line) , Perturbed Grid (dotted line)</li></li></ul><li>SpectrumSharingGain<br />20<br /><ul><li>K number of active femtocells
  126. 126. FOP set of frequencies assigned to one operator
  127. 127. F set of frequencies shared by operators
  128. 128. Simulation assumptions:
  129. 129. Fixed Outage Level
  130. 130. Constant number of </li></ul>femtocells per frequency<br />Franco Mazzenga, Marco Petracca, Remo Pomposini, Francesco Vatalaro, Romeo Giuliano. Performance Evaluation of Spectrum Sharing Algorithms in Single and Multi Operator Scenarios. IEEE VTC2011-Spring International Workshop on Broadband evolved Femtocell Technologies, 15-18 May 2011, Budapest, Hungary.<br />
  131. 131. Reusedistance<br />21<br /><ul><li>DFS algorithm
  132. 132. performs an autonomous redistribution of the minimum frequency reuse distance
  133. 133. tends to shrink the variance of the obtained distributions
  134. 134. Reduce the effect of the most harmful interferers for the considered femtocell</li></li></ul><li>Conclusions<br /><ul><li>The problemofinterferencebetweenfemtocells in a dense scenario hasbeenconsidered
  135. 135. Oneeffectivesolutionbased on the adoption of algorithms for cognitive femtocellshasbeenproposed and their performance analyzedthorughsimulation
  136. 136. Prosof the proposedsolution:
  137. 137. Significantincreaseof the numberofactivenodes in the considered area
  138. 138. Verysimpleimplementationof the algorithm due to the usageofelementarystrategiesnotrequiring the coordinationbetweenfemto-BSs
  139. 139. Robustness against failure and defections from the algorithm
  140. 140. GDFS algorithm allows to reach performance very close to the optimal case
  141. 141. Future works:
  142. 142. DFSA withcooperationbetweenfemtocells
  143. 143. Studyofcomplexfemtocells network topologies and the rulesthatleadstothem</li></ul>22<br />
  144. 144. Educationactivities<br />Courses<br />Modulazione Numerica - Prof. Franco Mazzenga - Università Tor Vergata a.a. 2007/2008<br />Writing a ScientificPaper - UniveritàTor Vergata 14, 15 e 17 Aprile, 2008<br />Corso inter-dottorato su sistemi embedded, Aprile-giugno 2009, docenti vari, numero ore X<br />Seminars<br />Next Generation Networking: le tecnologie per l'accesso ultrabanda - Villa Mondragone, Università Tor Vergata - 31 Gennaio 2008 – Seminario <br />Le nuove frontiere della qualità nei media digitali - TouradjEbrahimi - Fondazione Ugo Bordoni - 4 Novembre 2008<br />Nuove frontiere nella gestione dello spettro radio – Joseph Mitola III – Fondazione Ugo Bordoni – 18 Giugno 2009<br />School<br />Scuola di Dottorato in Ingegneria dell'Informazione - Università di Napoli Federico II 25-29 Febbraio 2008 - 40 ore  <br />Lipari Summer School on "Mobile Computing and Communications: Towards the Next Generation of Networks" - 17-24 Luglio 2010<br />Didattica<br />Cultore della materia “Software per le Telecomunicazioni”<br />OFDM seminar within the course “Sistemi di radiocomunicazioni”<br />23<br />
  145. 145. Researchactivities<br /><ul><li>WiMAX system
  146. 146. Cognitive Radio
  147. 147. Opportunistic Spectrum Access
  148. 148. Dynamic Spectrum Management
  149. 149. 3GPP and 4G Femtocellsytems</li></ul>24<br />
  150. 150. Publications 1/2<br />25<br /><ul><li>International Journal
  151. 151. Andrea Detti, Pierpaolo Loreti, Remo Pomposini, “On the Performance Anomaly in WiMAXnetworks”, Wiley Journal on Wireless Communications and Mobile Computing, SpecialIssue on Wireless Technologies AdvancesforEmergency and RuralCommunications, 2008, ISSN: 1530-8669, doi: 10.1002/wcm.677
  152. 152. Book chapter
  153. 153. Franco Mazzenga, Marco Petracca, Remo Pomposini, Francesco Vatalaro. ImprovingQoSofFemtocells in Multi-operatorEnvironments. Springer Book on Trustworthy Internet
  154. 154. International Conference
  155. 155. Franco Mazzenga, Marco Petracca, Remo Pomposini, Francesco Vatalaro, Romeo Giuliano. Performance Evaluation of Spectrum Sharing Algorithms in Single and Multi Operator Scenarios. IEEE VTC2011-Spring International Workshop on Broadband evolved Femtocell Technologies, 15-18 May 2011, Budapest, Hungary.
  156. 156. F. Mazzenga, M. Petracca, R. Pomposini, F. Vatalaro, R. Giuliano. AlgorithmsforDynamicFrequencySelectionforFemto-cellsofDifferentOperators. In: 21st IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2010), Istanbul, Turkey, September 26-29 2010
  157. 157. F. Mazzenga, M. Petracca, R. Pomposini, F. Vatalaro. Impact on QoSofFemtocellsDefectingfromDynamicFrequencySelectionAlgorithms. In: 21st International Tyrrhenian Workshop on DigitalCommunications (ITWDC 2010): Trustworthy Internet, Ponza, Italy, September 2-8
  158. 158. F. Mazzenga, M. Petracca, R. Pomposini, R. Giuliano, M. Vari. An AlwaysAvailableControlChannelfor Cooperative Sensing in Cognitive Radio Networks. In: IFIP Wireless Days 2010, Venice, Italy, October 20-22 2010. DOI: 10.1109/WD.2010.5657704</li></li></ul><li><ul><li>R. Giuliano, F. Mazzenga, M. Petracca, R. Pomposini. Wireless Opportunistic Network Based on UWB forPreservingEnvironment. In: wetice, pp.192-196, 2010 19th IEEE International Workshops on Enabling Technologies: Infrastructuresfor Collaborative Enterprises, 2010. DOI: 10.1109/WETICE.2010.36
  159. 159. Marco Petracca, Franco Mazzenga, Remo Pomposini, Francesco Vatalaro, Romeo Giuliano. Impact of Control Channel Design on Cooperative Spectrum Sensing in Opportunistic Spectrum Access Networks. First International Conference on Advances in Cognitive Radio (COCORA 2011). 17-22 April 2011, Budapest, Hungary.
  160. 160. Marco Petracca, Remo Pomposini, Francesco Vatalaro. Dynamic Spectrum Access Techniques for Preservation of Environment and Cultural Heritage. 20th IEEE International Conference on Collaboration Technologies and Infrastructures. June 27th - 29th, 2011, Paris, France.
  161. 161. Andrea Detti, Claudio Loreti, Remo Pomposini, “OverlayBorůvkabasedAd-hocMulticastProtocol – Demonstration”, in ProceedingsofFifthAnnualMediterranean Ad Hoc Networking Workshop (Med-Hoc-Net 2006), Demo Session, Lipari, Sicilia, Italy, 14-17 Giugno 2006
  162. 162. Andrea Detti, Remo Pomposini, Roberto Zanetti, “A cross layerversionof OBAMP based on a proactiverouting: description and MANET test-bed”, in Proceedingsof First IEEE conference on Wireless Rural and EmergencyCommunications (WRECOM 2007), Roma, 1-2 Ottobre 2007
  163. 163. SubmittedPapers
  164. 164. Franco Mazzenga, Marco Petracca, Remo Pomposini, Francesco Vatalaro, Romeo Giuliano. Opportunistic Spectrum Access based on Underlay UWB Signalling. 2011 IEEE International Conference on Ultra-Wideband. 14-15 September 2011, Bologna Italy.</li></ul>26<br />Publications 2/2<br />
  165. 165. Regulatoryaspects<br />27<br /><ul><li>Assumption:
  166. 166. network operators make arrangements one with each other to allow the reciprocal exchange of operating frequency channels
  167. 167. the simultaneous mutual interchange of spectrum bands among network operators is not currently permitted
  168. 168. Policy programmefor the use of the European Union’s radio spectrum foresees an efficient and flexible spectrum management as well as the promotion of collective use of spectrum.
  169. 169. Radio Spectrum Policy Programme (RSPP) encourages the development of standards able to avoid harmful interference by means of efficient spectrum usage techniques, especially when high density of radio devices occurs</li></li></ul><li>Pout with 2 and 3 frequency bands<br /><ul><li>Random network
  170. 170. GDFS and ODFS show similarperformances
  171. 171. Perturbedgrid
  172. 172. GDFS slightlyoutperforms the ODFS
  173. 173. PC leadsto the best performance
  174. 174. Pout= 5%, activefemtocells
  175. 175. Random network: 14  68 femtocells
  176. 176. Perturbedgrid: 66120 femtocells
  177. 177. Increasing fiincrease the number of active femtocells per frequencies
  178. 178. Random Network, Pout= 5%
  179. 179. 2 freq: 34 served femtocells per frequency
  180. 180. 3 freq: 47 active femtocells per frequency
  181. 181. Regular grid
  182. 182. On-off behavior of the outage</li></ul>28<br /><ul><li>Random topology (solid line) , Perturbed Grid (dashed line)</li></li></ul><li>Defectionfrom the DFSA<br />29<br /><ul><li>2 cases
  183. 183. Femtocells can or can not adopt the DFS algorithm
  184. 184. Some femtocells are selfish
  185. 185. They do not turn into sensing mode
  186. 186. The selfish behaviour of femtocells does not cause a marked decrease of performance</li></ul>F. Mazzenga, M. Petracca, R. Pomposini, F. Vatalaro. Impact on QoS of Femtocells Defecting from Dynamic Frequency Selection Algorithms. In: 21st International Tyrrhenian Workshop on Digital Communications (ITWDC 2010): Trustworthy Internet, Ponza, Italy, September 2-8<br />

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