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Co-channel Interference Modelling Between RATs in Heterogeneous Wireless Networks

Co-channel Interference Modelling Between RATs in Heterogeneous Wireless Networks. Jason B. Ernst, University of Guelph Nidal Nasser, Alfaisal University Joel Rodrigues, University of Beira Interior. Presented at ICC 2012 – Wireless Network Symposium – June 14 th 2012. Introduction.

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Co-channel Interference Modelling Between RATs in Heterogeneous Wireless Networks

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  1. Co-channel Interference Modelling Between RATs in Heterogeneous Wireless Networks Jason B. Ernst, University of Guelph Nidal Nasser, Alfaisal University Joel Rodrigues, University of Beira Interior Presented at ICC 2012 – Wireless Network Symposium – June 14th 2012

  2. Introduction • Motivation • Background • Experiment Setup & Methodology • Performance Evaluation • Discussion • Conclusions & Future Work ICC 2012- Wireless Network Symposium - June 14th, 2012

  3. Motivation • Modern devices have many options for connectivity (radio access technologies) or RATs ICC 2012- Wireless Network Symposium - June 14th, 2012

  4. Motivation • How can we seamlessly switch between RATs or enable multiple RATs simultaneously? ICC 2012- Wireless Network Symposium - June 14th, 2012

  5. Motivation: Problems? • Interaction between RATs is not well studied • Simulation tools often ignore interference between Wi-Fi and Bluetooth for example ICC 2012- Wireless Network Symposium - June 14th, 2012

  6. Motivation: Problems? • Interaction between RATs is not well studied • Certain algorithms assume homogeneous link capacities ICC 2012- Wireless Network Symposium - June 14th, 2012

  7. Motivation: Problems? Source: Wikipedia Source: Cisco ICC 2012- Wireless Network Symposium - June 14th, 2012

  8. Motivation: Why Bother? • Many reasons why the ability to seamless switch RATs is important: • More robust and reliable communications • Failover to other networks using different RATs • Potentially increased battery life • Selecting the most energy efficient RAT when possible • Potentially improved performance • Enabling multiple RATs at once ICC 2012- Wireless Network Symposium - June 14th, 2012

  9. Background • Previous studies show that partial overlapping of Wi-Fi channels does not significantly affect performance [Mishal et al, 2006] • What about overlap between RATs(ex: Wi-Fi, Bluetooth, Zigbee)? ICC 2012- Wireless Network Symposium - June 14th, 2012

  10. Background • Will performance degrade with a small channel interfering with a larger channel? (Bluetooth interfering with Wi-Fi) • If not, is there a threshold number of Bluetooth interferers that causes performance degradation? ICC 2012- Wireless Network Symposium - June 14th, 2012

  11. Background • Will performance degrade with a larger channel interfering with a smaller channel? (Wi-Fi to Bluetooth interference) ICC 2012- Wireless Network Symposium - June 14th, 2012

  12. Background: Similar Studies • Shuaib et al [2005] • Bluetooth  Wi-Fi  Internet • Wi-Fi performance somewhat dependent on Bluetooth performance • Also only looks at Wi-Fi performance • We aim to send Bluetooth and Wi-Fi traffic independent of each other simultaneously • We aim to investigate both Wi-Fi and Bluetooth performance ICC 2012- Wireless Network Symposium - June 14th, 2012

  13. Background: Similar Studies • Carfang et al [2008] • More focused on how mobility affects communication in the face of interference • Guoet al [2010] • Focused on error rates and signal strengths while we are concerned with throughput ICC 2012- Wireless Network Symposium - June 14th, 2012

  14. Background: Simulation Interference Models ICC 2012- Wireless Network Symposium - June 14th, 2012

  15. Background: Interference Avoidance Techniques • In Bluetooth 1.2: Adaptive Frequency Hopping • Tries to sense what channel Wi-Fi is using and avoid those frequency ranges • What happens when Wi-Fi saturates the area as is common now? • Other techniques where Wi-Fi and Bluetooth chips communicate directly to avoid • What happens when using external Bluetooth adaptors, chips that do not support etc? ICC 2012- Wireless Network Symposium - June 14th, 2012

  16. Experiment Setup • An equal number of Bluetooth and Wi-Fi devices • Located within a lab at the University of Guelph ICC 2012- Wireless Network Symposium - June 14th, 2012

  17. Laptop Node ICC 2012- Wireless Network Symposium - June 14th, 2012

  18. Methodology • FTP file transfers between nodes • Input from /dev/random on Ubuntu 11.10 • Wi-Fi file size was 10 megabytes • Bluetooth file size was 1 megabyte • Difference is because of the order of magnitude difference in link capacity so that a single transfer would finish roughly at the same time ICC 2012- Wireless Network Symposium - June 14th, 2012

  19. Methodology • Up to 6 laptops using each technology (6 Bluetooth and 6 Wi-Fi laptops) • Experiment performed late in the evening when few students use the campus Wi-Fi to decrease external interference • 30 Repetitions for each data point • Throughput is averaged across all nodes using particular technology ICC 2012- Wireless Network Symposium - June 14th, 2012

  20. Performance Evaluation ICC 2012- Wireless Network Symposium - June 14th, 2012

  21. Performance Evaluation ICC 2012- Wireless Network Symposium - June 14th, 2012

  22. Discussion • Bluetooth performance particularly is affected by Wi-Fi nodes in the region • Fig 2: 2, 3, 4 devices all show decreased performance due to interference • In some cases Wi-Fi nodes are also affected by Bluetooth interference • Fig 3: 3 devices ICC 2012- Wireless Network Symposium - June 14th, 2012

  23. Discussion • Decreased performance due to increased contention within the technology more to blame than interference between technologies, but still some effect • In future experiments, it may be best to vary the number of one type of node at a time to isolate the cause of decreased performance ICC 2012- Wireless Network Symposium - June 14th, 2012

  24. Conclusions & Future Work • Results show that Bluetooth is significantly affected by Wi-Fi interference within the same channel range • Result also showed limited cases of Wi-Fi being affected by Bluetooth interference • Results make the case that simulation tools should begin to support interference modelling between technologies ICC 2012- Wireless Network Symposium - June 14th, 2012

  25. Conclusions & Future Work • In future experiments, vary number of nodes with a particular RAT while leaving other constant • Expand to include other RATs, ex Zigbee • Vary the distance, introduce mobility • Develop heterogeneous access schemes that avoid interference between RATs ICC 2012- Wireless Network Symposium - June 14th, 2012

  26. Thank you for Attending! Questions? Jason Ernst, University of Guelph jernst@uoguelph.ca ICC 2012- Wireless Network Symposium - June 14th, 2012

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