1. July 2011
Project: IEEE P 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 , USA]
Voice:[ ], FAX: [ ],
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 P 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 P
Mineo Takai, UCLA

2. UCLA Computer Science Department
July 2011
Intelligent Spectrum Sensing for Vehicular Communications in the ISM Bands
Mineo Takai
Jitin Bajaj
Wooseong Kim
Brian Choi
Mario Gerla
UCLA Computer Science Department
Mineo Takai, UCLA

3. July 2011
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 IEEE p (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. July 2011
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
July 2011
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
July 2011
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 b/g
In-band channel sensing; current channel
Mineo Takai, UCLA

7. July 2011
Scanning Cycle
Mineo Takai, UCLA

8. Experimental Result (1)
July 2011
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)
July 2011
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. July 2011
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