An architecture for realizing joint communication and sensing based on an orthogonal frequency division multiplexing communication system

Abstract

The present invention discloses an architecture for realizing joint communication sensing based on an orthogonal frequency division multiplexing (OFDM) communication system, including: a frame transmission link for OFDM communication sensing integration that meets the 802.11 protocol at the transmitting end, and at the receiving end, there are two OFDM receiving links and a channel state information ratio (CSIR) feature sensing module. The frame transmission link adds auxiliary sensing components on the standard 802.11 OFDM physical layer; for the two OFDM receiving links at the receiving end, the frequency offset estimation and timing error estimation results of one of them are shared. According to these results, the frequency offset and timing error of both paths are corrected simultaneously, and the current object position features are obtained through the shared CSIR feature sensing module. Through multi-frame accumulation, the time-frequency transformation is performed on the features of consecutive multi-frames to obtain the final object speed. The present invention occupies only 0.48% of the communication bandwidth in the worst case to complete the real-time sensing task. The mutual cooperation between sensing and communication can significantly improve the spectrum utilization rate and greatly reduce the equipment cost and power consumption of additional deployments.

Description

Technical Field

[0001] The present invention relates to the field of joint communication sensing, and more particularly to a joint communication sensing architecture implemented based on an orthogonal frequency division multiplexing (OFDM) communication system. Background Art

[0002] With the prevalence of hypertension, metabolic syndrome, and cardiovascular diseases in the elderly population, the demand for long-term health monitoring in indoor environments is also increasing continuously. The monitoring content includes real-time vital signs or information such as respiration, heartbeat, and falls, which can provide important clues for relevant medical problems. However, existing methods for monitoring such signs or information usually require patients to wear special devices, such as pulse oximeters and acceleration sensors, which is particularly inconvenient for the elderly population. Therefore, a contactless, easily deployable, and low-cost long-term wireless vital sign monitoring solution would be highly attractive.

[0003] However, the deployment of an increasing number of wireless vital sign sensing chips has shortcomings in terms of cost and frequency band management. In view of this, the concept of joint communication sensing has emerged, aiming to utilize existing communication hardware, signal processing modules, and transmission signals to construct a sensing system, and on the premise of not affecting their respective functions, significantly reduce the cost and power consumption of additional deployed devices, so as to be able to monitor the indoor environment in a contactless, easily deployable, and low-cost manner. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to address the deficiencies existing in the prior art, and propose an architecture for realizing joint communication sensing based on an orthogonal frequency division multiplexing communication system, which uses most of the hardware, signal processing modules, and transmission signals of the OFDM communication system to construct a system for obtaining sensing signals. The mutual cooperation between sensing and communication can significantly improve the utilization rate of the spectrum, and greatly reduce the cost and power consumption of additional deployed devices, so as to be able to monitor the health of indoor people in a contactless, easily deployable, and low-cost manner.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] An architecture for realizing joint communication and sensing based on an orthogonal frequency division multiplexing (OFDM) communication system, comprising: an OFDM communication and sensing integrated frame transmission link at the transmitter end that complies with the 802.11 protocol, and two OFDM receiving links at the receiver end; the frame transmission link is divided into an OFDM communication transmission link and a sensing frame transmission switching link; the OFDM communication transmission link is used in the communication mode; data passes through the OFDM communication baseband, pulse shaping and IQ modulator, and radio frequency amplifier, and then is transmitted through the transmitting link antenna; the sensing frame transmission switching link is used in the sensing mode, and the sensing frame transmission switching link replaces the OFDM communication baseband to generate sensing data, which is transmitted through the pulse shaping and IQ modulator, radio frequency amplifier, and then through the transmitting link antenna;

[0007] The two OFDM receiving links are divided into an OFDM communication receiving link and a sensing processing link; the OFDM communication receiving link receives data through the receiving antenna, directly digitally down-samples it to baseband signal data through the radio frequency LNA, finds the best sampling timing through the delayed packet detection module, calculates the frequency offset estimation through the frequency offset detection module, corrects the frequency offset through the frequency offset correction module, calculates the timing error estimation through the timing error detection module, compensates the error through the timing synchronization module, performs a fast Fourier transform (FFT) on the compensated preamble, calculates the channel state information (CSI) using the frequency domain information, i.e., channel estimation one, and finally performs channel equalization compensation; the compensated data is demapped, deinterleaved, and decoded by a convolutional code to obtain the received data;

[0008] The sensing processing link receives data through the receiving antenna, directly digitally down-samples it to baseband signal data through the radio frequency LNA, the frequency offset correction module shares the frequency offset estimation result of the OFDM communication receiving link to correct the frequency offset, the timing error detection module shares the timing error estimation result of the OFDM communication receiving link to compensate the timing error, performs a fast Fourier transform (FFT) on the compensated preamble, calculates the channel state information (CSI) using the frequency domain information, i.e., channel estimation two, and finally, the channel state information ratio, i.e., the CSIR feature sensing module divides the channel estimation one and channel estimation two of the OFDM communication receiving link and the sensing processing link, performs a Möbius transform, and through multi-frame accumulation, performs a time-frequency transform on the continuous multi-frame features to obtain the final object speed.

[0009] The sensing frame transmission switching link includes a timer and a read-only memory (ROM) for storing sensing data; the sensing data is the minimum data frame of the standard 802.11 protocol, i.e., the short preamble and the long training sequence (LTS), the header signal information, i.e., the Signal field, and a group of minimum unit data bits, with a duration of 24 microseconds. When sending sensing frames at intervals of 5 milliseconds, it occupies approximately 0.48% of the communication bandwidth of the transceiver.

[0010] Advantages of the present invention:

[0011] The architecture implemented by the present invention can occupy only 0.48% of the communication bandwidth in the worst case to complete real-time sensing tasks. The mutual cooperation between sensing and communication can significantly improve the utilization rate of the spectrum, and greatly reduce the equipment cost and power consumption of additional deployments. The simulation verification of the sensing mode is completed in the register transfer level design of the architecture, and the calculated average speed error is about 4%. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a frame transmission link block diagram of the integrated OFDM communication and sensing at the transmitting end provided by the present invention;

[0013] Figure 2 It is a schematic diagram of the data storage in the read-only memory (ROM) provided by the present invention;

[0014] Figure 3 It is a two-way OFDM receiving link block diagram at the receiving end provided by the present invention;

[0015] Figure 4 It is a schematic diagram of the simulation result of the example sensing feature provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] An embodiment of the present invention provides an architecture for realizing joint communication and sensing based on an orthogonal frequency division multiplexing communication system. It includes: as Figure 1 shown, the frame transmission link of the integrated OFDM communication and sensing that meets the 802.11 protocol and the two-way OFDM receiving link as Figure 3 shown.

[0017] As Figure 1 , the frame transmission link is divided into an OFDM communication transmission link and a sensing frame sending switching link. In the communication mode, the OFDM communication transmission link is used. The data passes through the OFDM communication baseband, pulse shaping and IQ modulator, and radio frequency amplifier, and then is sent through the transmitting link antenna. In the sensing mode, the sensing frame sending switching link is used. The sensing frame sending switching link replaces the OFDM communication baseband to generate sensing data, and after passing through the pulse shaping and IQ modulator, and radio frequency amplifier, it is sent through the transmitting link antenna.

[0018] The sensing frame sending switching link includes a timer and a read-only memory for storing sensing data, namely ROM. The sensing data is the minimum data frame of the standard 802.11 protocol, namely the short preamble and the long training symbol (LTS), the header signal information (Signal field), and a group of minimum unit data bits. As Figure 2 shown, the duration is 24 microseconds. When the sensing frame is sent at an interval of 5 milliseconds, it occupies about 0.48% of the communication bandwidth of the transceiver.

[0019] As Figure 3, the two-way OFDM receiving link is divided into an OFDM communication receiving link and a sensing processing link.

[0020] The OFDM communication receiving link receives data through the receiving antenna, directly digitally down-samples it to baseband signal data after passing through the RF LNA, finds the optimal sampling timing through the delayed packet detection module, calculates the frequency offset estimation through the frequency offset detection module, corrects the frequency offset through the frequency offset correction module, calculates the timing error estimation through the timing error detection module, compensates the error through the timing synchronization module, performs a fast Fourier transform (FFT) on the compensated preamble, calculates the channel state information (CSI) using the frequency domain information, that is, channel estimation one, that is, H1(f,t), and finally performs channel equalization compensation. Finally, the compensated data is demapped, deinterleaved, and decoded by the convolutional code to obtain the received data.

[0021] The sensing processing link receives data through the receiving antenna, directly digitally down-samples it to baseband signal data after passing through the RF LNA, corrects the frequency offset by sharing the frequency offset estimation result of the OFDM communication receiving link through the frequency offset correction module, compensates the timing error by sharing the timing error estimation result of the OFDM communication receiving link through the timing error detection module, performs a fast Fourier transform (FFT) on the compensated preamble, and calculates the channel state information (CSI) using the frequency domain information, that is, channel estimation two, that is, H2(f,t).

[0022] The specific expression of the channel estimation can be written as:

[0023] 1)

[0024] where represents the random phase offset caused by the physical layer of the receiving device. H s (f) represents the channel response caused by the static reflection path. A(f,t) represents the amplitude response of the moving object. represents the phase response of the moving object, where v(t) is the radial velocity of the moving object and λ represents the wavelength of the wireless signal.

[0025] Finally, the CSIR feature sensing module divides the channel estimation one, that is, H1(f,t), and the channel estimation two, that is, H2(f,t), of the OFDM communication receiving link and the sensing processing link, and performs a Möbius transform, as shown in formula (2).

[0026] 2)

[0027] where represents the random phase offset caused by the physical layer of the receiving device. H s,p (f) represents the channel response caused by the static reflection path of antenna one. H s,q(f) represents the channel response caused by the static reflection path of Antenna 2. α is the absolute distance ratio formed by the included angle from the object to Receiving Antenna 1 and Receiving Antenna 2. In the final simplified formula, A = A1, representing the amplitude response from the object to Receiving Antenna 1; B = H s,p . Represents the response of the static reflection to Receiving Antenna 1; D = H s,q . Represents the response of the static reflection to Receiving Antenna 2.

[0028] Through multi-frame accumulation, perform time-frequency transformation on the features of multiple consecutive frames to obtain the final object velocity:

[0029] 3)

[0030] Among them, represents performing a Fourier transform on the result of Formula 2. Among them, v is the radial velocity of the moving object, and λ represents the wavelength of the wireless signal.

[0031] The instance model system verifies the performance of the system through hardware simulation, collects the data information printed by the simulation, and uses MATLAB to draw the real part and imaginary part of its features. As Figure 4 (a) shows. Performing frequency-domain analysis on it, it can be seen that the calculated Doppler frequency of the object's movement is 10 Hz. As Figure 4 (b) shows, the simulation setting is 9.6 Hz, and the error is 4%. This fully demonstrates that the hardware system designed in this instance can accurately use the sensing components to calculate the moving speed of the object.

Claims

1. An architecture for realizing joint communication and sensing based on an orthogonal frequency division multiplexing communication system, characterized in that, Including: An OFDM communication and sensing integrated frame transmission link at the transmitting end that complies with the 802.11 protocol, and two OFDM receiving links at the receiving end; the frame transmission link is divided into an OFDM communication transmission link and a sensing frame transmission switching link; the OFDM communication transmission link is used in the communication mode; Data is transmitted through the sending link antenna after passing through the OFDM communication baseband, pulse shaping and IQ modulator, and radio frequency amplifier; the sensing frame transmission switching link is used in the sensing mode, and the sensing frame transmission switching link replaces the OFDM communication baseband to generate sensing data, and is transmitted through the pulse shaping and IQ modulator, radio frequency amplifier, and then through the sending link antenna; The two OFDM receiving links are divided into an OFDM communication receiving link and a sensing processing link; the OFDM communication receiving link receives data through the receiving antenna, directly digitally down-samples it to baseband signal data after passing through the radio frequency LNA, finds the best sampling timing through the delayed packet detection module, calculates the frequency offset estimation through the frequency offset detection module, corrects the frequency offset through the frequency offset correction module, calculates the timing error estimation through the timing error detection module, compensates the error through the timing synchronization module, performs a fast Fourier transform (FFT) on the compensated preamble, calculates the channel state information CSI, i.e., channel estimation one, using the frequency domain information, and finally performs channel equalization compensation; the compensated data is demapped, deinterleaved, and decoded by a convolutional code to obtain the received data; The sensing processing link receives data through the receiving antenna, directly digitally down-samples it to baseband signal data after passing through the radio frequency LNA, corrects the frequency offset by sharing the frequency offset estimation result of the OFDM communication receiving link through the frequency offset correction module, compensates the timing error by sharing the timing error estimation result of the OFDM communication receiving link through the timing error detection module, performs a fast Fourier transform on the compensated preamble, calculates the channel state information using the frequency domain information, i.e., channel estimation two. Finally, the channel state information ratio, i.e., the CSIR feature sensing module, divides the channel estimation one and channel estimation two of the OFDM communication receiving link and the sensing processing link, performs a Möbius transform, and through multi-frame accumulation, performs a time-frequency transform on the continuous multi-frame features to obtain the final object speed.

2. The architecture for realizing joint communication and sensing based on an orthogonal frequency division multiplexing communication system according to claim 1, characterized in that, The sensing frame transmission switching link includes a timer and a read-only memory (ROM) for storing sensing data; the sensing data is the minimum data frame of the standard 802.11 protocol, i.e., the short preamble and the long preamble (LTS), the header signal information (Signal domain), and a group of minimum unit data bits, with a duration of 24 microseconds. When sending sensing frames at intervals of 5 milliseconds, it occupies approximately 0.48% of the communication bandwidth of the transceiver.

Images