JP2005303475A - Fading simulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform fading simulation utilizing a three-dimensional model capable of expressing a path using all resolutions of a DA converter. <P>SOLUTION: A fading circuit 203 generates a fading state of a propagation channel on the basis the parameter of reception power, a delay time and phase of an antenna element. Also, the fading circuit 203 sets attenuation quantities of a DA converter 205 and an attenuator 206 on the basis of the parameter of the attenuation coefficient. A control DA converter 204 applies analog control to the output voltage of the DA converter 205 by controlling a reference voltage of the DA converter 205. The DA converter 205 converts an output signal of the fading circuit 203 into an analog signal, and attenuates it on the basis of the control of a control DA converter 204. The attenuator 206 attenuates an output signal of the DA converter 205 on the basis of the control of the fading circuit 203. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fading simulator that simulates a propagation environment using a three-dimensional model.

  The fading simulator is a device that creates a spatio-temporal characteristic of an actual communication environment by using a cable connected between a transmitter and a receiver. In this fading simulator, a propagation model is important when simulating an actual communication environment. In a conventional fading simulator, a generalized propagation model equation is used to generate reception level fluctuations by time fluctuations with respect to distance, and a statistical model is used to determine the occurrence probability of multipaths and the level of each path. . Then, by changing the propagation channel stochastically in the fading simulator, the fading state is changed with the progress of time. A propagation channel is a path through which radio waves pass, and a fading phenomenon occurs when a plurality of propagation channels are erased or added together.

  By the way, in the field of mobile communications, the third generation mobile phone service has begun, and the data transmission speed with respect to the number of accommodations and the number of subscribers has been greatly improved. This is because the time axis at the time of broadband transmission can be effectively used by introducing the access technology using the frequency spread technology.

  Currently, as a next step, system development using a technique that uses a plurality of antenna elements such as an array antenna and MIMO (Multi-Input Multi-Output) that make effective use of the spatial axis of multiple radio wave propagation is in progress. In order to cope with such a system, it is necessary not only to change the received power with respect to time but also to represent a space in order to accurately reproduce each path. The domain representation model is not functional enough.

Therefore, it is expected to develop a fading simulator using a three-dimensional model that can three-dimensionally express the traffic of radio waves and can determine a propagation channel from an actual three-dimensional map.
JP 2002-333659 A

  However, if the attenuation corresponding to the moving distance of each path is reproduced only by the DA converter, the dynamic range is limited by the number of bits of the DA converter. The profile cannot be reproduced with sufficient resolution.

  The present invention has been made in view of this point, and an object thereof is to provide a fading simulator using a three-dimensional model that can express a path using all the resolutions of a DA converter.

  In order to solve this problem, the present invention is a fading simulator that simulates a propagation environment using parameters of a three-dimensional model generated by a propagation model generation device, and includes normalized received power, delay time, and phase. Fading generation means for adding spatial multipath to the input signal based on the parameters of the above, DA conversion means for converting the output signal of the fading generation means into an analog signal, and attenuation means for attenuating the output signal of the DA conversion means , And the fading generation means uses the attenuation coefficient parameter to set the attenuation amount in the DA conversion means and the attenuation means.

  According to the present invention, after the fading state is generated using the normalized received power, the long interval fluctuation value can be attenuated by the external analog circuit, so that the path is expressed using all the resolution of the DA converter. can do.

  The essence of the present invention is that normalization is performed so that the vector sum of the total power becomes 0 dB for each delay profile waveform, and the fading state is generated using the normalized received power, and then the long interval variation value is converted by an external analog circuit. It is to attenuate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment)
FIG. 1 is a system configuration diagram including a fading simulator according to an embodiment of the present invention.

  Propagation model generation apparatus 100 generates a spatial model and outputs the parameters of the spatial model to fading simulator 200. The fading simulator 200 simulates spatio-temporal characteristics of an actual communication environment using parameters of a spatial model, adds a spatial multipath to a signal output from the mobile device 300, and has a base station 400 having an array antenna. Output to.

  Next, the configuration of the propagation model generation apparatus 100 will be described using the block diagram of FIG. The propagation model generation apparatus 100 mainly includes a three-dimensional map data generation unit 101, a propagation environment construction unit 102, a channel impulse response acquisition unit 103, a spatiotemporal profile generation unit 104, and a parameter calculation unit 105. .

  The three-dimensional map data generation unit 101 generates three-dimensional map data using two-dimensional house map data such as actual field map / building information and altitude mesh data. The propagation environment construction unit 102 constructs a propagation environment in the base station using the three-dimensional map data and the base station data.

  The channel impulse response acquisition unit 103 receives data on the travel route of the mobile device, and estimates parameters such as the received electric field strength and the delay profile from the propagation environment constructed by the propagation environment construction unit 102 and the angle of arrival (Angle Of Arrival). ), Estimate the transmission angle (Angle Of Departure), and acquire the channel impulse response of the base station receiver.

  The spatio-temporal profile generation unit 104 receives data on the speed of the mobile device, and generates a spatio-temporal delay profile in the base station on the travel route of the mobile device by combining the channel impulse response and the arrival angle.

  The parameter calculation unit 105 uses the spatio-temporal delay profile to calculate various parameters (reception power, delay time, horizontal arrival angle, vertical arrival angle, attenuation coefficient) of the wave (ray) that has reached the base station receiver. Acquired and output to fading simulator 200. However, the received power is normalized so that the vector sum of the total power becomes 0 dB for each delay profile waveform. Note that 0 dB is set to be the maximum value of the DA converter.

  Next, a processing procedure in the propagation model generation device 100 will be described.

  First, the propagation model generation device 100 creates environment data (three-dimensional city data) using the map / building information of the actual field. In this environment data, a complex dielectric constant is set for each obstacle material.

  Next, the propagation model generation apparatus 100 estimates the estimation parameters such as the received electric field strength, the delay profile, the arrival angle, and the transmission angle using the environment data by the ray tracing method, and the channel impulse of the base station receiver. Get the response.

  Representative ray tracing methods include a launching method (launching-method) and an image method (Imaging-method). The launching method is a method in which a wave (ray) is discretely emitted from a transmitter at Δθ to search for a radio wave path, and the receiver is traced while being repeatedly reflected, transmitted, and diffracted by an obstacle. The image method is a method of searching radio wave paths by creating virtual images of all transmitters. The image method can be used as a model for evaluating a relatively narrow area such as a room because the number of obstacles increases, but the number of combinations of paths searched exponentially increases as the number of obstacles increases. The launching method increases the uncertainty of obstacle search (trace) due to the spread of discrete angles, but it is easy to devise speedup.

  In the ray tracing method, the received power is derived as the sum of all the rays that have arrived in the vicinity of the receiver, and the delay time is derived from the route length because the route of the arrived ray is clear. As a result of these, the channel impulse response of the receiver can be acquired. The maximum point that determines the estimation accuracy of the behavior of radio waves is 3D map data. In general, it is difficult to create a wide range of 3D map data, but the inventor has developed software that can automatically convert any area to a 3D from a house map.

  Next, propagation model generation apparatus 100 generates a spatio-temporal delay profile at the base station on the travel route of the mobile device by combining the channel impulse response and the arrival angle. A set of spatio-temporal delay profiles is a fading simulator space model.

  Next, the propagation model generation apparatus 100 uses the spatio-temporal delay profile to set various parameters (reception power, delay time, horizontal arrival angle, vertical arrival angle, Attenuation coefficient) is acquired and output to the fading simulator 200.

  The above is the description of the processing procedure in the propagation model generation device 100.

  Next, the configuration of fading simulator 200 will be described using the block diagram of FIG. The fading simulator 200 includes a position information storage unit 201, a phase calculation unit 202 for the number of antenna elements, a fading circuit 203 for the number of antenna elements, a control DA converter 204, a DA converter 205, and an attenuator 206. Consists mainly of.

  In the position information storage unit 201, the spatial position of the antenna element of the base station is set / stored in advance by the user. The spatial position of each antenna element stored in the position information storage unit 201 is obtained by correcting the phase variation of each antenna element circuit.

  The phase calculation unit 202 calculates each antenna element from the reference phase, horizontal direction arrival angle, vertical direction arrival angle parameter output from the propagation model generation apparatus 100 and the spatial position of the antenna element stored in the position information storage unit 201. Calculate the phase.

  The fading circuit 203 performs fading of the propagation channel based on the received power, delay time, and attenuation coefficient parameters output from the propagation model generation apparatus 100 and the phase parameter of each antenna element calculated by the phase calculation unit 202. Generate state.

  The control DA converter 204 controls the output voltage of the DA converter 205 in an analog manner by controlling the reference voltage of the DA converter 205 based on an instruction from the fading circuit 203. The DA converter 205 converts the output signal of the fading circuit 203 into an analog signal and attenuates it based on the control of the control DA converter 204. As a result, the entire output of the DA converter 205 can be attenuated while maintaining the resolution of the DA converter 205.

  The attenuator 206 attenuates the output signal of the DA converter 205 based on the control of the fading circuit 203. Note that the attenuator 206 gives a larger attenuation than the DA converter 205.

  Hereinafter, the configuration of the fading circuit 203 will be described with reference to FIG. FIG. 4 is a diagram showing the configuration of one fading circuit 203. Each fading circuit 203 is mainly composed of a FIFO type memory 301, a complex multiplier 302, a DSP 303, and a combiner 304.

  The FIFO type memory 301 is prepared for the maximum number of paths N, and delays the input signal by the delay amount controlled by the DSP 303. The complex multiplier 302 is prepared for the maximum number of paths N, and multiplies the input signal delayed by the FIFO type memory 301 by a complex coefficient controlled by the DSP 303.

  The DSP 303 sets the delay amount of the FIFO memory 301 according to the delay time parameter, and sets the complex coefficient of the complex multiplier 302 based on the received power and phase parameters. Further, the DSP 303 sets attenuation amounts of the DA converter 205 and the attenuator 206 based on the attenuation coefficient parameter.

  The synthesizer 304 synthesizes the output signals of the complex multipliers 302. As a result, the input signal from the mobile device or the like can be multipathed, phase rotation and level control can be performed for each path, and the spatiotemporal characteristics of the actual communication environment can be simulated.

  As described above, according to this embodiment, after normalizing the vector sum of the total power to 0 dB for each delay profile waveform and generating the fading state using the normalized received power, Since the value can be attenuated by an external analog circuit, the path can be expressed using all the resolution of the DA converter.

  INDUSTRIAL APPLICABILITY The present invention is suitable for use in the development of a mobile communication system that performs wireless communication using an apparatus that uses a plurality of antenna elements due to space reproduction capability. Further, the present invention can reproduce regional characteristics and propagation environment at an arbitrary traveling speed, and is suitable for use in the development of new mobile communications.

The figure which shows the system configuration | structure containing the fading simulator which concerns on one embodiment of this invention The block diagram which shows the structure of the propagation model production | generation apparatus which concerns on the said embodiment. The block diagram which shows the structure of the fading simulator which concerns on the said embodiment. The figure which shows the structure of the fading circuit of the fading simulator which concerns on the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Propagation model production | generation apparatus 101 3D map data production | generation part 102 Propagation environment construction part 103 Channel impulse response acquisition part 104 Spatio-temporal profile production | generation part 105 Parameter calculation part 200 Fading simulator 201 Position information storage part 202 Phase calculation part 203 Fading circuit 204 Control DA converter 205 DA converter 206 Attenuator 301 FIFO type memory 302 Complex multiplier 303 DSP
304 Synthesizer

Claims (3)

A fading simulator for simulating a propagation environment using parameters of a three-dimensional model generated by a propagation model generation device,
Fading generating means for adding a spatial multipath to the input signal based on normalized received power, delay time and phase parameters;
A DA converter for converting an output signal of the fading generation means into an analog signal;
An attenuator for attenuating the output signal of the DA converter;
The fading generation means sets attenuation amounts in the DA converter and the attenuator using attenuation coefficient parameters. A propagation model generation device for generating a three-dimensional model,
A spatiotemporal profile generating means for generating a spatiotemporal profile using three-dimensional map data, and a parameter calculating means for calculating a parameter representing a propagation channel used in the fading simulator according to claim 1 using the spatiotemporal profile. And a propagation model generation device. A propagation model generation device that determines a propagation channel using three-dimensional map data and calculates a parameter representing the propagation channel;
A spatial multipath is added to an input signal using normalized received power, delay time, and phase parameters, and the input signal after the spatial multipath addition is attenuated by a DA converter and / or an attenuator. Fading simulation system.

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