JP2021019240A - Radio wave propagation characteristic measurement system, dynamic propagation parameter estimation method, receiver, and radio wave propagation characteristic measurement program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate a propagation parameter even under a dynamic condition in which a propagation channel changes during measurement. SOLUTION: In a radio wave propagation characteristic measurement system including a transmitter for transmitting radio waves and a receiver for receiving radio waves transmitted by the transmitter by a synthetic aperture method, the receiver receives radio waves by the synthetic aperture method. For each arrival wave, based on the antenna, the arrival wave signal estimation unit that estimates the arrival wave signal based on the arrival angle, Doppler shift, and propagation delay for each arrival wave, and the arrival wave signal estimated by the arrival wave signal estimation unit. It is characterized by having a propagation parameter estimation unit that maximizes the power spectrum and estimates the propagation parameter, and an update unit that updates the complex amplitude for each incoming wave based on the propagation parameter estimated by the propagation parameter estimation unit. [Selection diagram] Fig. 1

Description

The present invention relates to a radio wave propagation characteristic measurement system, a dynamic propagation parameter estimation method, a receiver, and a radio wave propagation characteristic measurement program.

In the propagation channel measurement in the high frequency band, a synthetic aperture type channel sounder, which can be expected to simplify and miniaturize the device configuration, is often used. The synthetic aperture channel sounder measures the propagation channel while changing the measurement position one after another by rotating the antenna element attached to a turntable or the like.

Hung-Anh Nguyen et al., "Instantaneous Direction of Arrival Measurements in Mobile Radio Channels Using Virtual Circular Array Antennas", 2016 IEEE Globecom Workshops (GC Wkshps), Washington, DC, 2016, pp.1-7. Jeffrey A. Fessler et al., "Space-Alternating GeneralizedExpectation-Maximization Algorithm", IEEE Transactions on Signal Processing, vol.42, no.10, Oct 1994. Pp.2664-2677

In the conventional propagation channel analysis, the analysis is performed on the assumption of static conditions in which the propagation channel does not change during measurement. However, when analyzing the propagation channel characteristics of a user who moves by a vehicle or the like, a static condition in which the propagation channel does not change does not always hold.

The present invention provides a radio wave propagation characteristic measurement system that can accurately estimate propagation parameters even under dynamic conditions in which the propagation channel changes during measurement, a dynamic propagation parameter estimation method, a receiver, and radio wave propagation. It is an object of the present invention to provide a characteristic measurement program.

The radio wave propagation characteristic measurement system according to one aspect of the present invention is the radio wave propagation characteristic measurement system including a transmitter for transmitting radio waves and a receiver for receiving radio waves transmitted by the transmitter by a synthetic aperture method. The receiver has an antenna that receives radio waves by the combined aperture method, an arrival wave signal estimation unit that estimates the arrival wave signal based on the arrival angle, Doppler shift, and propagation delay for each arrival wave, and the arrival wave signal estimation unit. A propagation parameter estimation unit that maximizes the power spectrum for each arrival wave to estimate the propagation parameters based on the estimated arrival wave signal, and a complex amplitude for each arrival wave based on the propagation parameters estimated by the propagation parameter estimation unit. It is characterized by having an update unit for updating.

Further, the dynamic propagation parameter estimation method according to one aspect of the present invention is the dynamic propagation parameter estimation method using the combined aperture type radio wave propagation characteristic measurement system, in which the arrival angle and Doppler shift for each arrival wave are used. And the arrival wave signal estimation process that estimates the arrival wave signal based on the propagation delay, and the propagation parameter estimation process that estimates the propagation parameters by maximizing the power spectrum for each arrival wave based on the estimated arrival wave signal. It is characterized by repeating a series of processes including an update step of updating the complex amplitude for each incoming wave based on the propagated parameters.

Further, the receiver according to one aspect of the present invention includes an antenna that receives radio waves by a composite aperture method, and an arrival wave signal estimation unit that estimates an arrival wave signal based on an arrival angle, Doppler shift, and propagation delay for each arrival wave. Then, based on the arrival wave signal estimated by the arrival wave signal estimation unit, the propagation parameter estimation unit that estimates the propagation parameter by maximizing the power spectrum for each arrival wave and the propagation parameter estimated by the propagation parameter estimation unit are used. Based on this, it is characterized by having an update unit that updates the complex amplitude for each incoming wave.

According to the present invention, the propagation parameters can be estimated accurately even under dynamic conditions in which the propagation channel changes during measurement.

It is a figure which shows the configuration example of the radio wave propagation characteristic measurement system which concerns on one Embodiment. It is a figure which shows typically the signal model of the dynamic propagation channel of the radio wave received by the receiver which concerns on one Embodiment. It is a figure which shows the rotation of a receiving antenna schematically. It is a functional block diagram which shows the function which the receiver which concerns on one Embodiment has. It is a flowchart which shows the operation example of the receiver which concerns on one Embodiment.

An embodiment of a radio wave propagation characteristic measurement system (channel sounder) will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a radio wave propagation characteristic measurement system 1 according to an embodiment. As shown in FIG. 1, the radio wave propagation characteristic measurement system 1 includes, for example, a transmitter 2 and a receiver 3.

The transmitter 2 includes a transmitting antenna 20, and transmits radio waves that are multicarrier signals including a plurality of subcarriers such as OFDM (Orthogonal Frequency Division Multiplexing) to the receiver 3. The receiver 3 has, for example, one receiving antenna 32 that is rotated on the circumference by a turntable 30, and receives and analyzes radio waves transmitted by the transmitter 2 by a synthetic aperture method.

Generally, in a uniform circular array antenna (UCA) used in a radio wave propagation characteristic measurement system, a plurality of antennas are arranged at equal intervals on the circumference, and each antenna receives a radio signal. The receiver 3 may include a UCA, but here, a virtual UCA that operates in the same manner as the UCA by sequentially receiving radio signals while the receiving antenna 32 moves on the circumference and synthesizing the received signals. Is used.

FIG. 2 is a diagram schematically showing a signal model of a dynamic propagation channel of radio waves received by the receiver 3. The receiver 3 receives incoming waves (number of incoming waves: K) from a plurality of different directions. Hereinafter, the kth arrival wave in the K arrival waves will be referred to as #k (1 ≦ k ≦ K).

Further, the propagation parameter of the incoming wave is set to θ _k = [τ _k (t), φ _k (t), μ _k ]. Here, τ _k (t) represents the propagation delay of the arrival wave, φ _k (t) represents the arrival angle, γ _k represents the complex amplitude, and μ _k represents the Doppler shift.

FIG. 3 is a diagram schematically showing the rotation of the receiving antenna 32. Since the receiving antenna 32 rotates on the circumference, the phase of the signal received by the receiving antenna 32 changes according to the Doppler shift accompanying the movement of the receiving antenna 32. That is, the propagation parameter of the channel received by the receiving antenna 32 changes according to the rotation of the receiving antenna 32.

At this time, the mode vector α (θ) is defined as shown in the following equation (1) by using the propagation parameter θ _k .

The UCA mode vector α _UCA (φ) is expressed by the following equation (2).

The Doppler correction α _dop (μ) for correcting the UCA mode vector α _UCA (φ) based on the Doppler shift is expressed by the following equation (3).

The propagation delay vector α _τ (τ) is expressed by the following equation (4).

In the radio wave propagation characteristic measurement system 1, since the propagation channel of the signal received by the transmitter 2 is represented by the superposition of the incoming waves arriving from various directions, the dynamic channel signal of each arriving wave is expressed by the following equation ( It will be shown by the model shown in 5).

The above equation (5) will be described below. The UCA mode vector α _AOA (φ, μ) after Doppler correction is expressed by the following equation (6).

Next, the receiver 3 will be described in detail. FIG. 4 is a functional block diagram showing the functions of the receiver 3. As shown in FIG. 4, the receiver 3 includes a storage unit 40, an input unit 41, an initial setting unit 42, an incoming wave signal estimation unit 43, a propagation parameter estimation unit 44, an update unit 45, an output unit 46, and a channel signal calculation unit. Has 47.

The storage unit 40 is a database that stores measurement data (received signal) x of radio waves received by the receiver 3 via the receiving antenna 32, each data and a program described later, and is configured by a storage device such as a memory. .. The input unit 41 reads the measurement data x stored in the storage unit 40 and inputs it to the initial setting unit 42.

For example, the initial setting unit 42 sets the propagation parameter initial value shown in the following equation (7), and outputs the set propagation parameter initial value to the storage unit 40 and the incoming wave signal estimation unit 43.

The initial setting unit 42 is not limited to setting the propagation parameter initial value by the peak value of the power spectrum defined by the above equation (7), and may set an arbitrary value as the propagation parameter initial value.

The arrival wave signal estimation unit 43 estimates the arrival wave signal based on the arrival angle, Doppler shift, and propagation delay of the arrival wave #k using the following equation (8), and propagates the estimated arrival wave signal to the storage unit 40 and the propagation unit. Output to the parameter estimation unit 44.

The propagation parameter estimation unit 44 estimates the propagation parameter of the incoming wave #k by the parameter that maximizes the power spectrum by using the following equation (9), and stores the estimated propagation parameter estimated value in the storage unit 40 and the updating unit 45. Output to.

Further, when the number of repetitions (itr) reaches a predetermined value, the propagation parameter estimation unit 44 outputs the propagation parameter estimation result θ _k to the output unit 46.

The update unit 45 increments the itr, updates the complex amplitude of the arrival wave #k using the following equation (10), and outputs the update result to the arrival wave signal estimation unit 43.

The output unit 46 outputs the estimation result θ _k of the propagation parameter output by the propagation parameter estimation unit 44 to the storage unit 40.

The channel signal calculation unit 47 calculates the dynamic channel signal of each incoming wave and the like by using, for example, the above equation (5) and each data stored in the storage unit 40.

Next, an operation example of the receiver 3 will be described. FIG. 5 is a flowchart showing an operation example of the receiver 3. As shown in FIG. 5, in the receiver 3, the input unit 41 first inputs the received signal x to the initial setting unit 42 (S100).

Next, the initial setting unit 42 sets the initial value of the propagation parameter using, for example, the above equation (7) (S102).

Then, the arrival wave signal estimation unit 43 estimates the arrival wave signal (S104), and the propagation parameter estimation unit 44 estimates the propagation parameter (S106). Further, the propagation parameter estimation unit 44 determines whether or not the itr has reached the predetermined value (S108), and if the itr has not reached the predetermined value (S108: N), the process proceeds to S110, and the itr When the predetermined value is reached (S108: Y), the process proceeds to S112.

In the process of S110, the update unit 45 increments itr and updates the complex amplitude of the incoming wave #k using the above equation (10). That is, the receiver 3 repeats the processes of S104, S106, and S110 a predetermined number of times.

In the process of S112, the output unit 46 outputs the estimation result of the propagation parameter to the storage unit 40 and stores it. The estimation result of the propagation parameter stored in the storage unit 40 is used by the channel signal calculation unit 47 to calculate the dynamic channel signal and the like of each incoming wave.

In this way, the radio wave propagation characteristic measurement system 1 estimates the propagation parameter based on the Doppler shift of the radio wave transmitted by the transmitter 2, so that the propagation parameter is estimated even under dynamic conditions in which the propagation channel changes during measurement. Can be estimated accurately.

Each function of the receiver 3 shown in FIG. 4 may be partially or wholly configured by hardware, or may be configured as a program executed by a processor (not shown).

That is, the radio wave propagation characteristic measurement system 1 according to the present invention can be realized by using a computer and a program, and the program can be recorded on a recording medium or provided through a network.

The embodiments described above are exemplary and not limited to the embodiments of the present invention, and the present invention can also be implemented in various other modifications and modifications.

1 ... Radio wave propagation characteristic measurement system, 2 ... Transmitter, 3 ... Receiver, 30 ... Rotating table, 32 ... Receiving antenna, 40 ... Storage unit, 41 ... Input Unit, 42 ... Initial setting unit, 43 ... Arrival wave signal estimation unit, 44 ... Propagation parameter estimation unit, 45 ... Update unit, 46 ... Output unit, 47 ... Channel signal calculation Department

Claims (5)

A transmitter that transmits radio waves and
In a radio wave propagation characteristic measurement system including a receiver that receives radio waves transmitted by the transmitter by a synthetic aperture method.
The receiver
An antenna that receives radio waves by the synthetic aperture method,
An arrival wave signal estimation unit that estimates the arrival wave signal based on the arrival angle, Doppler shift, and propagation delay for each arrival wave.
A propagation parameter estimation unit that estimates the propagation parameter by maximizing the power spectrum for each arrival wave based on the arrival wave signal estimated by the arrival wave signal estimation unit.
A radio wave propagation characteristic measurement system characterized by having an update unit that updates a complex amplitude for each incoming wave based on the propagation parameters estimated by the propagation parameter estimation unit. The radio wave propagation characteristic measurement system according to claim 1, wherein the update unit further includes a channel signal calculation unit that calculates a dynamic channel signal based on a complex amplitude that has been updated a predetermined number of times. In a dynamic propagation parameter estimation method using a synthetic aperture type radio wave propagation characteristic measurement system,
The arrival wave signal estimation process that estimates the arrival wave signal based on the arrival angle, Doppler shift, and propagation delay for each arrival wave,
A propagation parameter estimation process that maximizes the power spectrum for each incoming wave and estimates the propagation parameters based on the estimated incoming wave signal.
A method for estimating dynamic propagation parameters, which comprises repeating a series of processes including an update step of updating the complex amplitude for each incoming wave based on the estimated propagation parameters. An antenna that receives radio waves by the synthetic aperture method,
An arrival wave signal estimation unit that estimates the arrival wave signal based on the arrival angle, Doppler shift, and propagation delay for each arrival wave.
A propagation parameter estimation unit that estimates the propagation parameter by maximizing the power spectrum for each arrival wave based on the arrival wave signal estimated by the arrival wave signal estimation unit.
A receiver characterized by having an update unit that updates the complex amplitude for each incoming wave based on the propagation parameters estimated by the propagation parameter estimation unit. A radio wave propagation characteristic measurement program for operating a computer as each part of the receiver according to claim 4.

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