Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Intelligent Spectrum Sensing for vehicular Communications in the ISM Bands] Date Submitted: [20 July, 2011] Source: [Mineo Takai, Jitin Bajaj, Wooseong Kim, Brian Choi, Mario Gerla] Company [University of California, Los Angeles] Address [3803 Boelter Hall, Los Angeles, CA 90095-1596, USA] Voice:[310-825-1888], FAX: [310-794-5056], E-Mail:[mineo@cs.ucla.edu] Re: [IG Spectrum Resources Usage] Abstract: [This document introduces a recent effort on dynamic spectrum sensing at UCLA.] Purpose: [To introduce an authors’ effort on dynamic spectrum sensing in the ISM bands relevant to the scope of IG SRU.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Mineo Takai, UCLA

2. Intelligent Spectrum Sensing forVehicular Communications in the ISM Bands Mineo Takai Jitin Bajaj Wooseong Kim Brian Choi Mario Gerla UCLA Computer Science Department Mineo Takai, UCLA

3. Introduction • We have been conducting various research studies on vehicular communications • Vehicle-to-Vehicle (V2V) • Vehicle-to-Infrastructure (V2I) • Many existing studies assume a spectrum band dedicated for DSRC/WAVE • 7 channels with IEEE 1609 + IEEE 802.11p (US) • Mostly safety applications • We consider V2V/V2I communications via ISM bands for content distributions and other applications • 11 (3 non-overlapping) channels at 2.4GHz (US) • More channels at 5.8GHz Mineo Takai, UCLA

4. Cognitive Approach • ISM bands are used extensively for communications other than V2V / V2I • Adopt a cognitive radio approach to avoid interfering and / or being interfered with other communications • Primary Nodes (PNs): Residential APs (and associated STAs) • Secondary Nodes (SNs): Vehicular equipped STAs • Extend existing routing protocols to account for channels to use • Perform spectrum sensing to dynamically select the channel to use for communications • Regular channel scanning only is not adequate Mineo Takai, UCLA

5. CoRoute: PN Aware Routing High interference Zone D Selected route 4 11 1 1 1 6 Possible route 1 6 Low interference Zone S 1 11 6 1 3 Vehicle 3 AP with Channel 3 Mineo Takai, UCLA

6. Channel Workload Estimation • Channel workload estimation module implemented on a Software Defined Radio (SDR) • Sora academic kit from Microsoft Research • Channel workload (w) estimation: • Energy based channel sensing • Channel Clearance Assessment (CCA) for symbol duration • Scanning: • Full channel scanning, e.g. 11 channels in 802.11b/g • In-band channel sensing; current channel Mineo Takai, UCLA

7. Scanning Cycle Mineo Takai, UCLA

8. Experimental Result (1) • Run the workload estimation module while varying the actual workload offered by PNs • 7 scan cycles with 3s single channel scan time:28.2%, 40.5% and 59.7% respectively Mineo Takai, UCLA

9. Experimental Result (2) • Change the scanning cycle from 2s to 4s (50% offered workload) • measured workload values:42%, 40.5% and 38% respectively Mineo Takai, UCLA

10. Summary • We implemented channel workload estimation module on an SDR for V2V / V2I communications in the ISM bands • Estimated workload have a strong correlation with actual workload • A shorter scanning cycle gives better estimation • Future work • Implement a better estimation module to yields more accurate workload estimation with a longer scanning cycle • Devise OFDM subcarrier based Tx / Rx for better utilization of overlapping channels • Evaluate the performance of CoRoute on a UCLA owned vehicular testbed Mineo Takai, UCLA