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Backscattering system based on orthogonal frequency division multiple access technology

An orthogonal frequency division multiple access and backscattering technology, applied in the field of communication, can solve problems such as the difficulty of large-scale OFDMA network engineering, and achieve low-cost effects

Active Publication Date: 2020-09-08
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these 48 tags need to use an analog frequency synthesizer to achieve different frequency shifts. Once the sub-channel is replaced, the frequency shift frequency must be changed, and the hardware needs to be reconfigured. Large-scale OFDMA network brings huge engineering difficulties
In view of the fact that the biggest technical difficulty of current OFDMA backscatter lies in the coupling relationship between frequency synthesis and hardware, this patent provides a digital frequency synthesis algorithm at the software level to achieve frequency synthesis so that the control of sub-channels and the number of sub-channels can be controlled within Changes at the software level make it possible for the practical application of OFDMA backscatter networks

Method used

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  • Backscattering system based on orthogonal frequency division multiple access technology
  • Backscattering system based on orthogonal frequency division multiple access technology
  • Backscattering system based on orthogonal frequency division multiple access technology

Examples

Experimental program
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Effect test

Embodiment 1

[0104] Example 1: Parallel experiment; 100 tags were randomly placed in an area with a radius of 7 meters. Both the transmitter and receiver used Mango Communications WARP v3, working in the 2.4GHz frequency band, and connected to a Lenovo ThinkPad P51 notebook computer through a LAN. The transmitter transmits the excitation signal, and the synchronization modules of all tags start to perform their own subcarrier modulation after synchronizing with the excitation signal, and the output after phase modulation becomes the switch control logic signal of the I / Q channel through logical judgment, and controls the I channel switch respectively and Q switch to complete I / Q modulation. During this process, their digital frequency synthesis block follows the k and N parameters specified by the transmitter (see specification section 5). Since the sub-channels of all tags do not conflict with each other, their OFDMA signals can be successfully demodulated by the receiver.

Embodiment 2

[0105] Embodiment 2: subcarrier generation experiment. Deploy 1 tag 5 meters away from the transmitter. By modifying the control signaling of the transmitter, the digital frequency synthesis algorithm specifying the label traverses all k (k is an integer, corresponding to the subchannel number) in the case of N=1024. After demodulation by the receiver, the data rate of the physical layer on each sub-channel is obtained. Both the transmitter and receiver use Mango Communications WARP v3, the frequency band is 2.4GHz. The result is as Figure 4 shown.

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Abstract

The invention provides a backscattering system based on an orthogonal frequency division multiple access technology. The backscattering system comprises an analog part and a digital logic part, wherein the analog part comprises an antenna, radio frequency switches, an envelope detection circuit and a transmission line; the digital logic part comprises a digital frequency synthesis module based onIDFT; two paths of output of the digital logic part control all the radio frequency switches, and the envelope detection circuit provides input of the digital logic part. Through the design, an OFDMAbackscattering tag can work on any given sub-channel under the conditions that the OFDMA backscattering tag is not powered on again and hardware is not modified, and can work at a specified symbol rate. The design of the backscattering system provides a networking physical layer basis for large-batch OFDMA backscattering tags, and meets the increasingly enlarged capacity requirement of the Internet of Things.

Description

technical field [0001] The present invention relates to the technical field of communication, in particular to a backscattering system based on OFDMA technology. In particular, it relates to a design method of backscatter tags based on IDFT digital frequency synthesis, which is suitable for OFDMA networks. Background technique [0002] Backscatter communication has attracted extensive attention in the field of IoT in recent years. Its main feature is to use external electromagnetic waves to modulate to realize its own communication. Since electromagnetic waves do not need to be actively generated, even if they are generated for Wi-Fi communication, the power consumption is very low, only tens of microwatts (see NSDI paper by Bryce Kellogg et al. in 2016). However, with the expansion of the scale of the Internet of Things, the multi-access technology has gradually changed from time division multiplexing to frequency domain multiplexing. In 2019, Renjie Zhao and others publ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26
CPCH04L27/2626H04L27/2601H04L27/2634H04B5/72
Inventor 朱丰源冯宇达李倩茹田晓华王新兵
Owner SHANGHAI JIAO TONG UNIV