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Wi Vi Technology

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Medma Infomatix (P) Ltd.
Medma Infomatix (P) Ltd.

Seeing through walls using Wireless Vision Technology. Wi-Fi signals are typically information carriers between a transmitter and a receiver. In this paper, we show that Wi-Fi can also extend our senses, enabling us to see moving objects through walls and behind closed doors.

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Presented by: Shalini Tripathi “Wi-Vi Technology” -Seeing through walls using Wi-Fi
CONTENTS ❖ Introduction. ❖ Challenges faced in designing Wi-Vi ❖ Methods used to overcome the challenges. ❖ Components of Wi-Vi ❖ Implementation. ❖ Advantages ❖ Limitations ❖ Applications ❖ Conclusion and Future Scope
Wi Vi Technology
KEY IDEA
Challenges Faced in Designing Wi-Vi Challenge #: “Flash” Effect Building a device that can capture such reflections is difficult because the signal power after traversing the wall twice (in and out of the room) is reduced by three to five orders of magnitude . Even more challenging are the reflections from the wall itself, which are much stronger than the reflections from objects inside the room.
How Can We Eliminate the Wall’s Reflection? Wi-Vi uses interference nulling to cancel both the wall reflections and the direct signal from the transmitting to the receiving antenna, hence increasing its sensitivity to the reflections of interest. NULLING TO REMOVE THE FLASH  MIMO systems can pre-code their transmissions such that the signal received at a particular antenna is cancelled. This property can be tailored to eliminate the flash effect as well as the direct signal from the transmitting to the receiving antenna, thereby enabling Wi-Vi to capture the reflections from objects of interest with minimal interference.  At a high level, Wi-Vi’s nulling procedure can be divided into three phases: • Initial nulling • Power boosting • Iterative nulling
Algorithm for Wi-Vi Nulling
Components Main Components of Wi-Vi :- First component: It eliminates the flash from the wall by MIMO nulling. Second component: It helps in tracking the object moving by considering the object as the antenna array using the technique called inverse SAR.
How Can We track the movement of Humans? Mode 1# ISAR – Inverse Synthetic Aperture Radar The human motion is being tracked through the walls with the help of a technique known as Inverse Synthetic Aperture Radar (ISAR). The technique works as follows: When a person moves, he reflects the transmitted signal from different points in space. We can conceptually think of the person as a moving antenna . The device captures consecutive time samples and treats them as consecutive spatial samples . Using standard antenna array processing, it is able to indentify the relative angle of the person's motion with respect to the device. We extend this method to track multiple humans by using the smoothed MUSIC algorithm
Tracking Motion
Through-Wall Gesture-Based Communication Mode2# Gesture-Based Communication Through Wall Gesture Based Communication, to wirelessly send any message to the computer, a human has to carry a wireless device with him. We have picked two simple body gestures to refer to '0' and '1' bits. A human behind a wall may use a short sequence of these gestures to send a message to Wi-Vi. After applying a matched filter, the message signal looks similar to standard BPSK encoding (a positive signal for a '1' bit, and a negative signal for a '0' bit) and can be decoded by considering the sign of the signal.
Wi-Vi Setup & Working Any objects that the signals hit including the wall create identical reflections, they too are cancelled out by this nulling effect. Only those reflections that change between the two signals, such as those from a moving object, arrive back at the receiver.
Detection Accuracy of Wi-Vi for Different Types of Obstructions
Advantages Wi-Vi is relatively a low-power, low-cost, low bandwidth, and accessible to average users.  Wi-Vi requires only few MHz of bandwidth and operates in the same range as Wi-Fi. It operates in ISM band. Wi-Vi can perform through-wall imaging without access to any device the other side of the wall.  Wi-Vi employs signals whose wavelengths are 12.5 cm. Extend human vision beyond the visible electromagnetic range, allowing us to detect objects in the dark or in smoke.
Limitations Display has very low resolution.We cannot detect humans behind concrete walls thicker than 8". To achieve a narrow beam the human needs to move by about 4 wavelengths (i.e., about 50 cm).
Wi Vi Technology
Wi Vi Technology
Conclusion  Wi-Vi, a wireless technology that uses Wi-Fi signals to detect moving humans behind walls and in closed rooms. In contrast to previous systems, which are targeted for the military, Wi-Vi enables small cheap see-through-wall devices that operate in the ISM band, rendering them feasible to the general public, without carrying any transmitting device. Future Scope Wi-Vi could be built into a Smartphone or a special handheld device. Evolution of seeing humans through denser building material and with a longer range. High quality images.
Thank You

More Related Content

Wi Vi Technology

  • 1. Presented by: Shalini Tripathi “Wi-Vi Technology” -Seeing through walls using Wi-Fi
  • 2. CONTENTS ❖ Introduction. ❖ Challenges faced in designing Wi-Vi ❖ Methods used to overcome the challenges. ❖ Components of Wi-Vi ❖ Implementation. ❖ Advantages ❖ Limitations ❖ Applications ❖ Conclusion and Future Scope
  • 5. Challenges Faced in Designing Wi-Vi Challenge #: “Flash” Effect Building a device that can capture such reflections is difficult because the signal power after traversing the wall twice (in and out of the room) is reduced by three to five orders of magnitude . Even more challenging are the reflections from the wall itself, which are much stronger than the reflections from objects inside the room.
  • 6. How Can We Eliminate the Wall’s Reflection? Wi-Vi uses interference nulling to cancel both the wall reflections and the direct signal from the transmitting to the receiving antenna, hence increasing its sensitivity to the reflections of interest. NULLING TO REMOVE THE FLASH  MIMO systems can pre-code their transmissions such that the signal received at a particular antenna is cancelled. This property can be tailored to eliminate the flash effect as well as the direct signal from the transmitting to the receiving antenna, thereby enabling Wi-Vi to capture the reflections from objects of interest with minimal interference.  At a high level, Wi-Vi’s nulling procedure can be divided into three phases: • Initial nulling • Power boosting • Iterative nulling
  • 8. Components Main Components of Wi-Vi :- First component: It eliminates the flash from the wall by MIMO nulling. Second component: It helps in tracking the object moving by considering the object as the antenna array using the technique called inverse SAR.
  • 9. How Can We track the movement of Humans? Mode 1# ISAR – Inverse Synthetic Aperture Radar The human motion is being tracked through the walls with the help of a technique known as Inverse Synthetic Aperture Radar (ISAR). The technique works as follows: When a person moves, he reflects the transmitted signal from different points in space. We can conceptually think of the person as a moving antenna . The device captures consecutive time samples and treats them as consecutive spatial samples . Using standard antenna array processing, it is able to indentify the relative angle of the person's motion with respect to the device. We extend this method to track multiple humans by using the smoothed MUSIC algorithm
  • 11. Through-Wall Gesture-Based Communication Mode2# Gesture-Based Communication Through Wall Gesture Based Communication, to wirelessly send any message to the computer, a human has to carry a wireless device with him. We have picked two simple body gestures to refer to '0' and '1' bits. A human behind a wall may use a short sequence of these gestures to send a message to Wi-Vi. After applying a matched filter, the message signal looks similar to standard BPSK encoding (a positive signal for a '1' bit, and a negative signal for a '0' bit) and can be decoded by considering the sign of the signal.
  • 12. Wi-Vi Setup & Working Any objects that the signals hit including the wall create identical reflections, they too are cancelled out by this nulling effect. Only those reflections that change between the two signals, such as those from a moving object, arrive back at the receiver.
  • 13. Detection Accuracy of Wi-Vi for Different Types of Obstructions
  • 14. Advantages Wi-Vi is relatively a low-power, low-cost, low bandwidth, and accessible to average users.  Wi-Vi requires only few MHz of bandwidth and operates in the same range as Wi-Fi. It operates in ISM band. Wi-Vi can perform through-wall imaging without access to any device the other side of the wall.  Wi-Vi employs signals whose wavelengths are 12.5 cm. Extend human vision beyond the visible electromagnetic range, allowing us to detect objects in the dark or in smoke.
  • 15. Limitations Display has very low resolution.We cannot detect humans behind concrete walls thicker than 8". To achieve a narrow beam the human needs to move by about 4 wavelengths (i.e., about 50 cm).
  • 18. Conclusion  Wi-Vi, a wireless technology that uses Wi-Fi signals to detect moving humans behind walls and in closed rooms. In contrast to previous systems, which are targeted for the military, Wi-Vi enables small cheap see-through-wall devices that operate in the ISM band, rendering them feasible to the general public, without carrying any transmitting device. Future Scope Wi-Vi could be built into a Smartphone or a special handheld device. Evolution of seeing humans through denser building material and with a longer range. High quality images.