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WiSee refers to whole home gesture recognition using wireless. It can be defined as an interface which provides maximum ongoing transmission in the environment. Since it is wireless it is free from line of sight. It is able to crosswise throughout the wall. University of Washington Scientists attain their goal without the requirement of instrumentation in the human body with a sensing device. WiSee can be worked with the help of wireless sources such as Wi-Fi. When humans move within the environment WiSee looks at the Doppler shifts and multiple path distortions which occurs in the Wi-Fi signals.
WiSee: A video
The word gesture can be defined as the natural way of interaction. Many algorithms are there to interrupt gestures. Most of these interactions can be interrupted using vision, infrared, electric sensing, ultrasonic, wearable sensors and wireless signals.
University of Washington Scientists worked without the line of sight and through the walls and made WiSee possible to cover large areas. The main advantage of WiSee is that it is helpful for detecting gestures which are unseen. They are completely independent of light conditions. It means WiSee is able to work in day and night then indoor and outdoor. Infrastructures are widely used here . There is a need of wide range for wireless signals. All the devices need the requirement of wireless interfaces. There is no use of new hardware. WiSee requires low power consumption.
Here the motions are controlled by a trend technology called MIMO (Multiple input Multiple output). They provide multiple antennas for the improvement of throughput. They are estimated by sending known preamble from each transmitter sequentially. Each transmitter stops the transmission of second antenna to the other receiver.
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WiSee dealing with the motion interference
MIMO helps to remove or null the reflections from Static objects by estimating the channels. Using this they will null the signal at the receiver. As a result objects can be detected.
It is done by ISAR (Inverse synthetic aperture radar). It will stimulate the antenna array. They are very cheaper. Numbers of antennas are less. They are more compact. They depend on speed of motion. They will estimate the angle first that is the relative movement. Also,an algorithm is used to separate multiple humans.
WiSee tracking humans
WiSee is independent of the user’s location. Doppler shift are used to measure movement speed for identifying gesture.
Doppler shift is a frequency change of a wave. In the case of wireless signals if there is a multiple path reflection from the human body in the form of waves the performance of the human will result in the pattern of Doppler shifts at the wireless receiver. User shifts or moving hand, far away, results in the negative Doppler. If it moves near to the receiver it will result in the positive Doppler. But experiments say the human motion will detect as very small Doppler. Order of magnitude in Doppler shift is smaller than the bandwidth of Wi-Fi. Therefore the identification results in a big challenge. WiSee introduces a receiver design which helps to identify the Doppler shift at the resolution.
WiSee helps to transform the received Wi-Fi signals to a narrowband pulse. As a result the receiver will track the energy of this narrowband pulse for detecting the smaller Doppler shifts. When the object is static the emitting frequency will be same at everywhere. When the object starts moving, frequency will be higher when positive Doppler frequency is lower than the negative Doppler. The shift of frequency depends from its original frequency and speed from its direction of movement.
Movements of human will result in very small shifts. Therefore they are very difficult to detect.
MIMO have an inherent capability to 802.11n which helps to focus on gesture and motion. They will enable multiple transmitters to send the packets concurrently to the MIMO receiver. The wireless signals or reflections from human in a wireless transmitter can be distinguished using MIMO receiver. In a two bed room apartment Wisee will be able to extract a rich of gesture information’s from wireless signals. Using two wireless signals placed in the living room gesture recognition will be enabled.
We can conclude that it is possible to transform Wi-Fi into a gesture recognition sensor. Here Wisee will help to enable whole home gesture recognition and human recognition. Therefore many applications are introduced using this WiSee technology.
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