Adrian Loch, Hany Assasa, Joan Palacios, and Joerg Widmer IMDEA Networks Institute. Hans Suys and Björn Debaillie Imec Belgium

Transcription

1 1 Adrian Loch, Hany Assasa, Joan Palacios, and Joerg Widmer IMDEA Networks Institute Hans Suys and Björn Debaillie Imec Belgium

2 2 Zero Overhead Device Tracking December 14, 2017 Paper Lamp Omnidirectional Wireless Communication < 6 GHz Searchlight

3 2 Zero Overhead Device Tracking December 14, 2017 Paper Lamp Omnidirectional Wireless Communication < 6 GHz Searchlight Directional Wireless Communication > 6 GHz (mmwave)

4 3 Zero Overhead Device Tracking December 14, 2017 Node A Node B Mechanism as in IEEE ad

5 3 Zero Overhead Device Tracking December 14, 2017 Node A Node B Mechanism as in IEEE ad

6 3 Zero Overhead Device Tracking December 14, 2017 Node A Node B Mechanism as in IEEE ad

7 3 Zero Overhead Device Tracking December 14, 2017 Node A Node B Approaches in Related Work

8 3 Zero Overhead Device Tracking December 14, 2017 Node A Node B Approaches in Related Work

9 3 Zero Overhead Device Tracking December 14, 2017 Node A Node B Approaches in Related Work

10 4 Zero Overhead Device Tracking December 14, 2017 Node A Node B Our multi-lobe approach

11 4 Zero Overhead Device Tracking December 14, 2017 Node A Node B Our multi-lobe approach

12 4 Zero Overhead Device Tracking December 14, 2017 Node A Node B Our multi-lobe approach

13 4 Zero Overhead Device Tracking December 14, 2017 Node A Node B Our multi-lobe approach

14 4 Zero Overhead Device Tracking December 14, 2017 Node A Our multi-lobe approach

15 5 Zero Overhead Device Tracking December 14, 2017 Zero Overhead Device Tracking Exploiting Preambles in ad Golay Sequences for Phase Detection Practical Challenges Preamble Robustness Handling Obstacles Evaluation Practical Results Simulation Results Conclusions

16 6 The core of our mechanism +1 TX -1 RX

17 Zero Overhead Device Tracking December 14, Receiving half of the preamble using multilobe pattern No modification to the transmitter nor the operation of IEEE ad Modified receiver fully backward compatible with regular devices Receiver uses misalignment information for both TX and RX steering Acknowledgment STF 3.63 µs CEF Payload Data STF 1.2 µs CEF Payload

18 Zero Overhead Device Tracking December 14, Receiving half of the preamble using multilobe pattern No modification to the transmitter nor the operation of IEEE ad Modified receiver fully backward compatible with regular devices Receiver uses misalignment information for both TX and RX steering Acknowledgment STF 3.63 µs CEF Payload Data STF 1.2 µs CEF Payload TX RX TX RX

19 Zero Overhead Device Tracking December 14, Receiving half of the preamble using multilobe pattern No modification to the transmitter nor the operation of IEEE ad Modified receiver fully backward compatible with regular devices Receiver uses misalignment information for both TX and RX steering Acknowledgment STF 3.63 µs CEF Payload Data STF 1.2 µs CEF Payload TX TX RX RX Pattern switch time is below 50 ns on state-of-the-art antennas and can be as low as 50 ps

20 Zero Overhead Device Tracking December 14, Designing two-lobe beampatterns to track devices Relative phase-shift among the two lobes is designed to be 180º Receiver receives part of the preamble using the two-lobe beampattern Comparing first and second half of preamble reveals orientation Two-lobe beampatterns are feasible using analog beamforming

21 Zero Overhead Device Tracking December 14, Detecting phase shift among preamble halves Direct phase comparison is challenging due to beam pattern change Properties of Golay sequences allow for robust phase shift detection Correlation results in a positive (0º shift) or negative (180º shift) spike Obtain Golay sequence via one-lobe and two-lobe beam pattern Compute cross-correlation of both sequences Rotation to the left Rotation to the right Well aligned

22 10 Making our approach work on practical hardware

23 Zero Overhead Device Tracking December 14, Packet detection with only part of the preamble STF A receiver may only receive half of the STF in the worst case We show in practice that an ad decoder works with such an STF Receiver can equalize packet since CEF is received with regular pattern TX: COTS ad RX: Keysight Wideband Waveform Center

24 Zero Overhead Device Tracking December 14, Obstacles and misalignments are radically different In case of antenna misalignment, the current path is still available In case of blockage, the nodes must find an entirely new path ad beacon sweeps address both but we focus on misalignment

25 Zero Overhead Device Tracking December 14, Obstacles and misalignments are radically different In case of antenna misalignment, the current path is still available In case of blockage, the nodes must find an entirely new path ad beacon sweeps address both but we focus on misalignment Our mechanism can track both paths individually

26 Zero Overhead Device Tracking December 14, Obstacles and misalignments are radically different In case of antenna misalignment, the current path is still available In case of blockage, the nodes must find an entirely new path ad beacon sweeps address both but we focus on misalignment Our mechanism can track both paths individually Finding the reflected path is a separate problem

27 13 Practical and simulative results

28 Zero Overhead Device Tracking December 14, Implementation on phased antenna array at IMEC Highly flexible 60 GHz frontend featuring 2x8 antenna elements Antenna allows for phase and amplitude control of each element Testbed is fully controlable from Matlab, allowing for rapid prototyping TX Antenna RX Antenna Control PC Oscilloscope Differential IQ Signal Generator Differential IQ Control PC and TX Equipment RX Equipment

29 Zero Overhead Device Tracking December 14, Implementation on phased antenna array at IMEC One side of the link rotates according to real-world gyroscope traces Automatic beam-steering adjustment based on correlation output Steering error always below 5º which results in up to 2x throughput gain Seamless and fast error recovery Walking movement at indoor speed

30 16 Zero Overhead Device Tracking December 14, 2017 We achieve significant performance improvements We measure performance both in terms of throughput and angle error Device tracking can maintain a high rate in spite of movement/rotation The angle error is below the outage threshold even for strong rotations Periodic controlled rotation of one of the ends of the link

31 Zero Overhead Device Tracking December 14, Full protocol stack implementation on NS-3 and Matlab Matlab symbol-level simulation including raytracer and 60 GHz model NS-3 packet-level simulation in direct execution mode with TCP Cubic Large number of randomly generated scenarios using gyroscope traces ad suffers massive SNR drops due to rotation whereas our approach continuously adapts to such rotations Our approach reduces the angle error to below 3º in almost all cases

32 Zero Overhead Device Tracking December 14, Full protocol stack implementation on NS-3 and Matlab Matlab symbol-level simulation including raytracer and 60 GHz model NS-3 packet-level simulation in direct execution mode with TCP Cubic Large number of randomly generated scenarios using gyroscope traces ad suffers massive SNR drops due to rotation whereas our approach continuously adapts to such rotations Our approach reduces the angle error to below 3º in almost all cases

33 18 Summary of our insights

34 Zero Overhead Device Tracking December 14,

35 Zero Overhead Device Tracking December 14, Goal: track movement and rotation of IEEE ad devices with zero overhead and no changes to the operation of the standard

36 Zero Overhead Device Tracking December 14, Goal: track movement and rotation of IEEE ad devices with zero overhead and no changes to the operation of the standard Challenges: Designing multi-lobe beam patterns that allow for misalignment tracking Detecting the phase shift among non-equalized preamble halves

37 Zero Overhead Device Tracking December 14, Goal: track movement and rotation of IEEE ad devices with zero overhead and no changes to the operation of the standard Challenges: Designing multi-lobe beam patterns that allow for misalignment tracking Detecting the phase shift among non-equalized preamble halves Contributions and results: Accurate per-packet movement and rotation tracking of a path Mechanism is fully backward compatible with IEEE ad devices 1. No change to the operation nor frame format of IEEE ad 2. Mechanism works even when communicating with legacy nodes

38 Zero Overhead Device Tracking December 14, Goal: track movement and rotation of IEEE ad devices with zero overhead and no changes to the operation of the standard Challenges: Designing multi-lobe beam patterns that allow for misalignment tracking Detecting the phase shift among non-equalized preamble halves Contributions and results: Practical implementation on a full bandwidth 60 GHz testbed 1. Testbed features an electronically steerable phased antenna array 2. We achieve an angle error below 5º for most cases Extensive simulation campaign achieving up to 2.38x higher throughput

39 Zero Overhead Device Tracking December 14, Implemented and tested on the PHARA4 60 GHz WiFi solution

40 Zero Overhead Device Tracking December 14,