| In recent years,the Internet of Things has developed rapidly,and the scale of end devices has quickly expanded.However,replacing the batteries of a large number of IoT end devices requires high maintenance costs.Therefore,the power consumption of the end device has become one of the main factors limiting the long-term large-scale deployment of the Internet of Things.The reason why the end device power consumption remains high is the power consumption of communication and computing.To reduce the power consumption of IoT end devices,environmental backscatter communication technology has emerged in recent decades,which has been able to reduce the communication power consumption of the end device from the mW level to the ?W level.The Wi-Fi backscat-ter communication system has the advantage of being easy to deploy because it can be deployed with existing Wi-Fi equipment.However,the existing Wi-Fi backscatter communication system is still based on a processor to implement calculation and control functions.On the one hand,it limits the further reduction of the power consumption and cost of Wi-Fi backscatter end devices.On the other hand,it is difficult to reconstruct the end device.If you want to design an IoT end device with different functions,you need to rewrite different end device codes to modify the processor control logic.Because of the limitations of the existing Wi-Fi backscatter end device architecture,this paper proposes to float the end device's processor function in the Wi-Fi backscatter communication system to the gateway to form a new type of Wi-Fi without a processor.Backscatter communication system.The advantage of this system is that removing the processor allows the end device to have lower cost and power consumption.On the other hand,since the gateway directly controls the end device instead of the processor,it is possible to modify the end device' s control logic by changing the control logic of the gateway.Function,so the end device has the advantage of easy reconfiguration.However,due to the lack of a processor,such a system design will face three difficulties.The Wi-Fi gateway directly controls the non-processing end device,that is,now con-trols the end device's digital sensor.However,only the digital bus signal can control the end device's digital sensor.Therefore,the end device must realize the conversion of the complex coded and modulated Wi-Fi signal into a digital bus signal.However,it is dif-ficult to achieve this conversion when the end device lacks a processor.To solve this difficulty,this article will study the relationship between Wi-Fi data and signal envelope,and use Wi-Fi signal envelope to convey information.Pass the clock and data informa-tion of the bus together through appropriate coding,and design the corresponding circuit to extract the clock and data information to generate the corresponding SPI bus signal.The processor-less end device lacks the control of the processor,and it isn't easy to reflect the Wi-Fi signal at the right time without destroying the Wi-Fi protocol.In response to this difficulty,this article uses the Wi-Fi signal with a clock to control the end device for backscatter communication.Therefore,the clock that controls the backscatter is synchronized with the clock signal in the Wi-Fi signal,so as long as the synchronization is properly designed The clock can backscatter at the right time without breaking the Wi-Fi protocol.Backscatter communication will produce harmonic interference due to the use of switches for modulation,but the processorless end device lacks corresponding calculations to achieve the suppression of harmonics.In this paper,the analog filtering method is used to filter the backscatter signal to reach the suppression of the harmonic interference of the backscatter communication.Finally,this paper designs a corresponding prototype system,and evaluates the sys-tem's uplink communication rate of 40kbps and downlink communication rate of 100kbps,and the required power consumption is only 211.6?W after evaluation. |
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