1. Presented at ICC 2012 – Wireless Network Symposium – June 14 th 2012

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

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

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

5.  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 5

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

7. 7 Source: Wikipedia Source: Cisco

8.  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 8

9.  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 9

10.  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 10

11.  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 11

12.  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 12

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

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15.  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 15

16.  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 16

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18.  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 18

19.  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 19

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22.  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 22

23.  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 23

24.  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 24

25.  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 25

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