1. Interference Detection for Sensing
2006 March
Interference Detection for Sensing
Authors:
IEEE P Wireless RANs Date:
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 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 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at
>
Huawei

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

3. 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

4. (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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. (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

13. Correlation of PNi and PN
Huawei

14. 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

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

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

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

18. 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