Vânia goncalves isbo ng wi nets - accounting interference


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Vânia goncalves isbo ng wi nets - accounting interference

  1. 1. Accounting interference: impact of interference on revenue Vânia Gonçalves IBBT-SMIT, VUB NG Wireless Workshop Cognitive Networks: Interference Sensibility 21-01-10, IBBT-Ghent
  2. 2. Overview   Spectrum allocation   Spectrum is underutilised   Changes taking place   Spectrum sensing   Modelling revenue   Case studies   802.15.4 and Wi-Fi   UMTS and UWB   WiMAX and FWA   Conclusions 2
  3. 3. Spectrum allocation   Spectrum allocation has always been assigned on a static basis in order to avoid interference EFFICIENT? 3
  4. 4. Spectrum is underutilised McHenry M.,Tenhula P. & McCloskey D., Chicago Spectrum Occupancy Measurements & Analysis and a Long-term Studies Proposal, 2005 4
  5. 5. Spectrum is underutilised Willkomm D. et al, 2009 5
  6. 6. Changes are taking place   Regulatory changes: FSM, DSA, ...   Cognitive radios   Sharing is becoming a necessity   Coexistence of secondary networks with primary owners of spectrum is possible   Opportunities for new sources of revenue BUT… 6
  7. 7. Spectrum usage varies greatly in a matter of minutes 7
  8. 8. Spectrum sensing   Sensing is the enabler for spectrum sharing   But perfect sensing of primary users of spectrum is difficult   Technical requirements and procedures might still be set to mitigate harmful interference   Higher likelihood of services interfering with each other   Few incentives for primary owners to allow opportunistic/ secondary usage   Possible losses in revenue?   Important to model the impact of secondary users on primary users’ performance and primary owners’ revenue 8
  9. 9. Modelling revenue   Ercan et al. (2008) propose a three player Stackelberg game model between the PO, PUs and SUs in which:   SUs share the channel with primary users in time   Secondary user access through a non-perfect listen- before-send scheme   SUs are allowed to use the channel it when it is not being used by any PU but keeping interference to PUs below a maximum   Accounts for interference probability 9
  10. 10. Modelling revenue   Shown that the spectrum owner can enhance revenue by allowing opportunistic access with a non-zero interference probability to the primary users:   In exchange for the degraded QoS of the PUs due to interference from SUs, the PO offers the PUs a lower subscription fee   The enhancement of the revenue comes from the subscription fee of the SUs and better spectrum usage   Weaknesses:   Only one channel and a single spectrum owner is considered   Simple listen-before-send model   Maximum tolerated interference not dependent of technologies involved   The user utility metrics are assumed to be equal to their average throughput and not based on the time of application 10
  11. 11. Case studies   Maximum tolerated interference varies with technologies involved: estimation of interference probability different if PU technology ≠ SU technology   The impact to the application/service needs to be considered   Service metrics  User throughput  Delay/jitter  Users’ outage  Coverage  QoS  …   The context the application serves  emergency services ≠ office building 11
  12. 12. 802.15.4 and Wi-Fi   Office environment scenario   200 802.15.4 sensor nodes spread out over 3 floors   Main interference source: wifi networks Nighttime measurements Measured at IBCN, 2009 12
  13. 13. ZigBee and Wi-Fi Daytime measurements Measured at IBCN, 2009 13
  14. 14. UMTS and UWB   Operational UMTS network   Main interference source: UWB devices   Distance of 1 meter between UMTS terminal and UWB devices   UMTS in idle mode   Degradation is noticeable but connection is not lost, except for the cases with 12 and 16 UWB devices Hämäläinen, M et al., 2006 14
  15. 15. UMTS and UWB   UMTS in voice and data modes   With a small number of active devices, no measurable impact is seen   For voice connections, the connection is lost with more than 12 active UWB devices Hämäläinen, M et al., 2006 15
  16. 16. WiMAX and FWA   FWA service   Main interference source: WiMAX   Urban dense areas   Co-channel, adjacent channel, and zero guard band transmission Shamsan and Rahman, 2008 16
  17. 17. WiMAX and FWA   FWA service   Main interference source: WiMAX   Urban dense areas   Co-channel, adjacent channel, and zero guard band transmission Shamsan and Rahman, 2008 17
  18. 18. Conclusions   Spectrum sensing may create opportunities for efficient usage of spectrum and increased revenue   The impact of interference to be a combination of the interference generated by the technologies, application and context   Maximum tolerated interference to be dependent on intended output of service metrics and technologies   Next steps:   To be able to narrow down to costs -> definition of concrete scenarios:  Frequency bands  Spectrum access  Interference scenarios/technologies involved  Application and context 18
  19. 19. Thank you! Questions? vania.goncalves@vub.ac.be 19
  20. 20. References   Hamalainen, M., et al., Co-existence measurements between UMTS and UWB systems. IEE Proceedings - Communications, 2006. 153(1): p. 153-158.   Shamsan, Z.A. and T.A. Rahman, On the comparison of intersystem interference scenarios between IMT-Advanced and Fixed Services over various deployment areas at 3500MHz. Progress In Electromagnetics Research, 2008. 5: p. 169–185.   Ercan, A.O., et al., A Revenue Enhancing Stackelberg Game for Owners in Opportunistic Spectrum Access., in Proceedings of DySPAN 2008, 2008.   Willkomm, D., et al., Primary user behavior in cellular networks and implications for dynamic spectrum access. Comm. Mag., 2009. 47(3): p. 88-95. 20