doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 1 The case for wideband sensing IEEE P Wireless RANs Date: Authors: Notice: This document has been prepared to assist IEEE 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 grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 2 Abstract This presentation builds the case for wideband sensing – in particular it proposes the use of shadowing correlation across frequencies to weed out unqualified users and enable cooperation between qualified users only. Such cooperation enables us to lower the system probability of harmful interference while also reducing the probability of missed opportunity.

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 3 Preliminaries Probability of Harmful Interference (PHI): The probability that a cognitive radio system interferes with the primary user. – For a single radio with the primary signal at a given SNR, this P HI is the same as the P MD – This definition assumes that a radio that mis-detects the primary will always interfere with its receivers. γ is the received SNR of the primary signal and FΓ(γ) is its cumulative density function (CDF). Probability of Missed Opportunity (PMO): The probability that a cognitive radio system does not use a vacant channel. – For a single radio, this probability is the same as the probability of false alarm (PFA) in classical detection theory

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 4 Single radio performance characteristics N0 = -96 dBm SNR Mean = 3.2 dB SNR Std Dev = 5.5 dB

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 5 Noise + interference uncertainty Spurious Tones, filter shapes, Out of band interference, temperature changes – all impact our knowledge of noise. Calibration can reduce uncertainty but not eliminate it Cabric et al

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 6 Single radio performance with uncertainty N0 = -96 dBm SNR Mean = 3.2 dB SNR Std Dev = 5.5 dB Noise Uncertainty = 1dB For low P HI we suffer very high P MO

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 7 Cooperative Performance For low P HI we suffer very high P MO This is because there is no way to distinguish between good and base radios

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 8 Sutro Tower San Francisco 28 co-located transmitters Fremont Peak Fremont 10 co-located transmitters

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 9 Frequency correlation of shadowing from collocated transmitters From indoor UWB channel experiments we see strong shadowing correlation between frequencies – even frequencies 1GHz apart

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 10 Wideband sensing algorithm Anchor band decisionH A,1 H A,0 Primary band decisionH P,1 H P,0 Global DecisionH­ 1 H­ 0 H­ 1

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 11 Wideband Sensing Performance Wideband sensing allows a single user to achieve the target probability of harmful interference

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 12 Scaling with frequency correlation asdadadadadada The more the correlation across frequencies, the more gains from wideband sensing

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 13 Ternary Voting Anchor band decisionH A,1 H A,0 Primary band decisionH P,1 H P,0 Global DecisionH­ 1 H­ 0 AA Radios abstain if they don’t see the anchor

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 14 Cooperation between wideband radios Cooperation between wideband radios improves on both P HI and P MO

doc.: IEEE /0354r0 Submission July 2007 Shrindhar Mubaraq Mishra, UC BerkeleySlide 15 Future Work –Move from single anchor to multiple primaries scheme –Idea is more to identify good radios coarsely rather than calibrate to a single very known anchor. Want a simple rule like: If a radio sees ~5 TV channels, it is a qualified user. –Qualifying a wideband radio –Comments ?