Interference Detection for Sensing 2006 March Interference Detection for Sensing Authors: IEEE P802.22 Wireless RANs Date: 2006-07-17 Notice: This document has been prepared to assist IEEE 802.22. 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 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf 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 Chair Carl 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 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at patcom@iee.org. > Huawei

TWO INTERFERENCE DETECTIONS Orthogonal Interference Detection Interference Detection Using Preambles Incumbent signal selection without service interruption can be achieved. Huawei

INTRODUCTION If interference (or incumbent user signal) exists in the frequency domain of the received signals, Otherwise, Xk,i is the symbol transmitted at time i for the kth subcarrier; Hk,i is the channel response at time i for the kth subcarrier; Yk,i is the received symbol at time i for the kth subcarrier; Ik,i is the interference signal at time i for the kth subcarrier. Huawei

(1) Orthogonal Interference Detection Assume in coherence time and coherence bandwidth, Hk,i is constant. Assume (Qk,i, Qk,i+1 ) is orthogonal to transmitted data (Xk,i, Xk,i+1) A group of received data (Yk,i, Yk,i+1 ) are correlated with orthogonal signal. If interference exists: else: Determine whether interference exists using energy detection: If , interference exists, else, interference does not exist. T (Xk,i, Xk,i+1): interference detection threshold Huawei

Orthogonal Interference Detection for Multiple Symbols Use multi groups of received data to increase reliability of the detection Using data of N different time slots to form N-1 groups of signal vectors When , interference exists Using data of N different sub-carriers to form N-1 groups of signal vectors When , interference exists Huawei

Orthogonal Interference Detection Using Pilots The location of a pilot is known When Xk,i of a pilot is always “1” ,the equation for the judgement is When Xk,i of a pilot is alternatingly “1” or “-1” ,the equation for the judgement is Huawei

Orthogonal Interference Detection Using Traffic Data Traffic data are richer than pilots for interference detection Received symbols Yk,i are buffered Coding and modulation performed to get Xk,i If correct in decoding ,then detect interference based on the algorithm mentioned in the previous slide If erroneous in decoding ,then calculate PER (Packet Error Rate) : If PER>threshold, BS will schedule quiet periods Interference Detection at receiver Huawei

Simulation 1 Detection probabilities under INR=30dB of the algorithm. The upper figure illustrates the detection with one group of symbols while the bottom one illustrates the detection with average of 8 groups of symbols. Huawei

Simulation 2 Detection probabilities under INR=20dB of the algorithm. The upper figure illustrates the detection with one group of symbols while the bottom one illustrates the detection with average of 8 groups of symbols. Huawei

Simulation 3 Detection probabilities under INR=0dB of the algorithm. The upper figure illustrates the detection with one group of symbols while the bottom one illustrates the detection with average of 8 groups of symbols. Huawei

Conclusions Orthogonal Interference Detection Interference detection can be done without channel estimation Interference detection can be done without Service Interruption Multiple groups of received data can be used to increase detection reliability Interference detection can be done using traffic data by performing decoding and demodulation at the receiver. Huawei

(2) Interference Detection Using Preambles Assume the system bandwidth is 6MHz PNs can be training sequences of frame preambles for downlink frames PNs can be training sequences of burst preambles for uplink frames Huawei

Correlation of PNi and PN Huawei

Principle of Interference Detection Using Preambles The transmitted signal (PNm) has correlation with the received signal Energy of the received signal Then get sum of power of interference and noise based on the second equation Calculate sum of interference and noise power for each fractional band and compare the power with pre-determined threshold. If (interference + noise) power is larger than the threshold, there is interference on this part of bandwidth. Huawei

Simulation 1 Performance of interference detection using frame preambles, INR = 0dB Huawei

Simulation 2 Performance of interference detection using frame preambles, INR = -10dB Huawei

Simulation 3 Detection probability vs INR of interference detection using frame preambles for threshold =0.25 Huawei

Conclusions Interference Detection with Preambles Interference detection can be done without channel estimation Interference detection can be done without Service Interruption Do not need to schedule QPs, without increasing overhead It can be applied for fractional bandwidth detection Huawei