CN1585308A - Multi-path simulation system and method - Google Patents

Abstract

The invention provides a multi-path simulation system and method, which utilize an anechoic chamber to avoid external electromagnetic interference and other uncontrollable signal transmission paths generated in a test, and distribute and adjust a signal into a plurality of simulation signals so as to simulate attenuation and delay generated by the signal respectively during the transmission of the plurality of paths. The radio wave darkroom is also provided with a rotary table controlled by the control unit and can bear the wireless communication device to be tested, and the radio wave receiving and transmitting state of the wireless communication device to be tested is measured by changing the direction of the receiving and transmitting signal of the communication device.

Description

Multi-path simulation system and method

technical field

The present invention relates to a multi-path (multi-path) simulation system and method, in particular to a shielded anechoic chamber (shielded anechoic chamber) to avoid external electromagnetic interference, and adjust a signal distribution into multiple analog signals to simulate the signal in multiple A multi-path simulation system and method for attenuation and delay generated during transmission of multiple paths.

Background technique

In recent years, with the rapid development of wireless communication technology, the applications of mobile phone and wireless local area network (WLAN) are becoming more and more common. Compared with the physical line signal transmission with only a fixed transmission path, the wireless signal transmission has a multi-path characteristic. The so-called multiple paths mean that when a wireless signal propagates in space, due to the characteristics of the space, such as walls, obstacles, etc., the signal will be reflected, so there are multiple transmission paths between the transmitting end and the receiving end. For the receiving end, these signals arriving from different paths will generate multiple path effects such as inter-symbol interference and fading due to phase difference, which increases the complexity of signal transmission and reception. degree and instability, and this multipath effect is a phenomenon that exists in most real environments.

However, for manufacturers of wireless communication equipment, such as telephone handsets, telephone base stations, wireless network interface cards (network interface cards), wireless bridges (access point), etc., traditionally, most of them have not been able to accurately grasp In the environment of test conditions, such as a general open space, to simulate the signal reception of the product, it is completely impossible to provide a reliable test report for the product. Because in this environment, it is usually difficult to avoid electromagnetic interference (EMI) from the outside and generate redundant reflection paths; and in actual test operations, it may also be limited by space characteristics and lack flexibility. Or although a channel emulator is used to simulate the actual environment, the channel emulator uses a cable mode test system, which excludes the antenna of the wireless communication device to be tested, and cannot test the important antenna diversity (antenna diversity) Performance, so it is impossible to provide a complete and fair test report for the product. Therefore, there is an urgent need for a convenient and effective way to simulate the multi-path characteristics, and then test the strain performance of its products in an environment close to the actual use, as an important basis for design and development.

Contents of the invention

In view of this, the present invention proposes a multi-path simulation system and method, which can not only avoid external electromagnetic interference and generate redundant reflection paths, but also not be limited by the communication space in operation, so as to achieve the purpose of simulating and controlling the real radio wave space .

In order to achieve the above object, the present invention provides a multi-path simulation system, which includes a signal generating device for generating a signal; a signal simulation unit coupled to the signal generating device, which can adjust the distribution of a signal to N The analog signal is used to simulate the attenuation and delay of the signal when it is transmitted through N paths, where N is an integer greater than 1. The simulation system also includes a shielded anechoic chamber, which contains N antennas, coupled to the signal simulation unit, and used to transmit the N simulation signals respectively.

The present invention also provides a multi-path simulation method, which at least includes: generating a signal; and adjusting the distribution of this signal to N analog signals, so as to simulate the attenuation and delay generated when the signal is transmitted in N paths, where N is An integer greater than 1; using N antennas to respectively transmit the N analog signals, wherein the N antennas are located in an anechoic room; and using a communication device in the anechoic room to receive the N analog signals.

The invention utilizes the anechoic chamber to avoid external electromagnetic interference and generation of redundant reflection paths. The inner wall of the anechoic chamber is made of special materials. When the signal is transmitted to the inner wall, most of its energy is absorbed, and the intensity of the reflected signal can be minimized. In the present invention, after considering the space transmission attenuation and other line attenuation in the anechoic chamber, the signal simulation unit is used to attenuate the transmitted signal to simulate the attenuation of the signal in the actual space transmission process, so that the transmission attenuation can be controlled to reach The degree is equivalent to the transmission delay, and it is not limited by the size of the anechoic chamber, so that the signal transmission in various environments can be simulated. By means of the aforementioned means, the present invention can achieve the purpose of simulating and controlling the real radio wave space, and can also use the controllable simulated radio space to conduct various radio experiments or measurements to obtain evaluation results close to the real use environment.

The present invention also provides a method for measuring the diversity gain (diversity gain) of a communication device. The communication device has a switchable single antenna mode and an antenna diversity mode, and is placed in an anechoic chamber. The method includes the following steps: a. Set the communication device to a single antenna mode; b. generate a test signal; c. attenuate the test signal by the first attenuation range; d. adjust the distribution of the test signal to N analog signals to simulate the test signal in the The attenuation and delay produced respectively during transmission of N paths, wherein N is an integer greater than 1; e. Utilize N antennas located in the anechoic chamber to transmit the N analog signals; f. The communication device receives the N analog signals; g .Measure a signal parameter received by the communication device to obtain a reference value; h. Switch the communication device to the antenna diversity mode, and attenuate the test signal by a second attenuation range, so that the signal parameter received by the communication device is equal to the reference value; and i. calculating the difference between the first and second attenuation amplitudes, which is the antenna diversity gain of the communication device.

Brief description of the drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

In the attached picture,

FIG. 1A is a block diagram of a preferred embodiment of the multipath simulation system of the present invention;

FIG. 1B is a block diagram of another preferred embodiment of the multipath simulation system of the present invention;

Fig. 2 is the action flowchart of the preferred embodiment of the multipath simulation method of the present invention;

Fig. 3 is the action flowchart of measuring antenna diversity gain by using the multi-path simulation system of the present invention;

FIG. 4 is a flow chart of another embodiment of measuring antenna diversity gain by using the multipath simulation system of the present invention.

Detailed ways

The implementation of the multipath simulation system and method of the present invention will be described in detail below with specific embodiments, and an application example of the present invention, that is, the measurement of diversity gain of a wireless communication device will be described.

FIG. 1A is a block diagram of a preferred embodiment of the multi-path simulation system of the present invention. In the figure, the multipath simulation system 10a is used to simulate a wireless communication space with N paths (N is an integer greater than 1), which includes: a signal generating device 11 for generating a signal; a signal simulation unit 12a coupled to Connected to the signal generating device 11, the signal distribution is adjusted to N analog signals, thereby simulating the attenuation and delay generated respectively when the signal is transmitted in the N paths; a control unit 13a is coupled to the signal generating device 11, to generation of the control signal; and an anechoic chamber 14 for isolating external electromagnetic interference and redundant reflection paths, thereby minimizing the useless reflection effect inside the anechoic chamber 14 .

The signal simulation unit 12a includes: an attenuation device 121, used to attenuate the signal generated by the signal generating device 11, and generate an attenuated signal; a power divider (power divider) 122, coupled to the attenuation device 121, to attenuate the signal The signal is divided into N sub-attenuation signals; N attenuators 123a, coupled to the power divider 122, are used to attenuate the N sub-attenuation signals, so as to simulate the attenuation generated when the signal is transmitted in N paths; and N delays The delay line 124 is coupled to the N attenuators 123a, and is respectively used to delay the N sub-attenuated signals attenuated by the N attenuators 123a, so as to simulate the delays generated when the signals are transmitted through the N paths.

In another embodiment, a reference path is selected from the N paths to simulate a direct path, and the delay line 124 on the reference path can be omitted. And, when N is equal to 2, a phase shifter (phase shifter) is added on the reference path to adjust the phase of the sub-attenuated signal after being attenuated by the attenuator 123a on the reference path, so that when the analog signal is transmitted in the two paths phase difference.

In Fig. 1A, the control unit 13a is also coupled to the attenuation device 121, and the attenuation device 121 can be a step attenuator (step attenuator), and the attenuation range is adjusted step by step by the control unit 13a, so as to facilitate the adjustment of the signal generating device 11. The generated signal simulates the attenuation caused by the wireless communication space transmission. Generally, the greater the attenuation, the longer the signal transmission distance. In addition, the control unit 13a can also be coupled to N attenuators 123a (not shown in the figure), so as to control the attenuation amplitudes of the N attenuators 123a respectively.

The interior of the anechoic chamber 14 includes: N antennas 141 respectively coupled to the N delay lines 124 of the signal simulation unit 12a for transmitting N analog signals respectively; and a communication device 142 for receiving the N analog signals. Wherein, the N antennas 124 are directional antennas, such as horn antennas, to form an antenna array.

The anechoic chamber 14 also includes a quiet zone 143 for placing the communication device 142 . The silent zone 143 is produced by the characteristics of the anechoic chamber 14 itself. In this zone, the signal emitted by the antenna 141, except the part that the antenna 141 is directly transmitted to the communication device 142 (that is, the direct path without reflection), has no other indirect paths. reflections are minimized. Therefore, placing the communication device 142 in the silent zone 143 can obtain a better simulation effect.

The anechoic chamber 14 also includes a turntable 144 for carrying the communication device 142 to change the azimuth of the communication device 142 for receiving signals. Because the change of this orientation affects the receiving characteristics of the communication device 142 to the signal, when the communication device 142 to be tested is tested by the simulation system 10a, the receiving orientation can be adjusted by the turntable 144 to measure the receiving characteristics of the communication device 142 in different orientations, Such as antenna diversity effect, and radiation pattern (radiation pattern) and so on.

In addition, in order to obtain a better simulation effect for the simulation system 10a, the signal generating device 11 uses a selected sample (Golden Sample) of the communication device 142, whose characteristics are far in line with the technical standards and specifications to be followed relative to the communication device 142, so The generated signal quality is better and meets the test requirements. In addition, a vector signal generator (vector signal generator) can also be used with a power amplifier as the signal generating device 11 as required, so that more accurate and diverse signals can be generated as required.

Please refer to FIG. 1A again, the control unit 13 a is also coupled to the turntable 144 to control the rotation angle of the turntable 144 . The control unit 13 a is also coupled to the communication device 142 to obtain the characteristics of the signal received by the communication device 142 . The signal characteristics here may include: signal strength, signal quality, frame error rate (Frame Error Rate), and data throughput (Throughput). Through the control unit 13a, in addition to controlling the signal generation and adjusting the attenuation of the signal, the turntable 144 can also be controlled to measure the antenna diversity effect and radiation field in different directions, and obtain the characteristics of the received signal for subsequent analysis step.

FIG. 1B is a block diagram of another preferred embodiment of the multi-path simulation system of the present invention. Compared with FIG. 1A , the multipath analog system 10 b in FIG. 1B utilizes the attenuator 123 b to combine the functions of the attenuating device 121 and the attenuator 123 a in FIG. 1A . Therefore, in the signal simulation unit 12b, the power divider 122 is directly coupled to the signal generating device 11, and the signal generated by it is divided into N sub-signals; N attenuators 123b are coupled to the power divider 122, and are used to attenuate The N sub-signals are used to simulate the attenuation of the signal when it is transmitted in the N paths; N delay lines (delay lines) 124 are coupled to the N attenuators 123b, respectively used to delay the attenuation by the N attenuators 123b The N sub-signals of simulating the delays generated when the signals are transmitted through the N paths. Likewise, in this preferred embodiment, the delay line 124 on a reference path among the N paths can also be omitted. When N is equal to 2, a phase shifter can be added on the reference path to adjust the phase of the sub-signal attenuated by the attenuator 123b on the reference path, so as to simulate the phase difference when the signal is transmitted on the two paths.

In addition, in FIG. 1B, the control unit 13b is coupled to N attenuators 123b, so as to adjust the attenuation amplitudes respectively. Other operating modes of the control unit 13b are the same as those of the control unit 13a in FIG. 1A. As for the composition and operation of the anechoic chamber 14, it is also the same as that of FIG. 1A.

Next, how to implement the multi-path simulation method of the present invention by using the simulation system 10a mentioned above will be described. FIG. 2 is an action flow chart of a preferred embodiment of the multi-path simulation method of the present invention. As shown in Figure 2, this method includes the following steps:

21 make the signal generating device 11 generate a signal;

22 using the attenuation device 121 to attenuate the signal to generate an attenuated signal;

23 using the power divider 122 to distribute the attenuation signal into N sub-attenuation signals;

24 Attenuate the N sub-attenuated signals respectively by N attenuators 123a, so as to simulate the attenuation generated when the signals are transmitted in N paths;

25. The N sub-attenuation signals are respectively delayed by N delay lines 124 to generate N analog signals to simulate the delays generated when the signals are transmitted in N paths;

26 using N antennas 141 to transmit the N analog signals respectively; and

27 Use the communication device 142 to receive the N analog signals.

In step 27, the rotation angle of the turntable 144 can also be adjusted through the control unit 13a, so as to change the orientation of the communication device 142 for receiving signals.

In this preferred embodiment, a reference path may also be selected among the N paths, and in step 25, N-1 delay lines 124 are used to respectively delay the N-1 sub-attenuations on the remaining paths outside the reference path signal (ie without delaying the sub-attenuated signal on the reference path). And, when N is equal to 2, a step is added between steps 25 and 26, using a phase shifter on the reference path to adjust the phase of the sub-attenuated signal on the reference path after being attenuated by the attenuator 123a to simulate the signal The phase difference that occurs when the two paths are transmitted.

In another preferred embodiment, the aforementioned simulation system 10b is used to implement the multi-path simulation method of the present invention. The difference with the process in Figure 2 lies in steps 22 to 25, wherein step 22 is omitted; in step 23, the signal is divided into N sub-signals by using the power divider 122; in step 24, the N attenuators 123b are used to attenuate the N sub-signals; and in step 25, the N sub-signals are respectively delayed by N delay lines 124 to generate N analog signals.

Using the multi-path simulation systems 10a and 10b of the present invention, various signal reception tests can be performed on wireless communication devices. A method for measuring the diversity gain of a wireless communication device using the analog systems 10a and 10b will be discussed below. Here, the communication device 142 in the analog systems 10a and 10b is a communication device that can be switched to a single antenna mode or an antenna diversity mode. FIG. 3 is a flow chart of the operation of measuring antenna diversity gain by using the multipath simulation system 10a of the present invention. As shown in Figure 3, this process includes the following steps:

31. Set the communication device 142 to a single antenna mode by the control unit 13a;

32 make the signal generating device 11 generate a test signal;

33 Utilize the attenuation device 121 to attenuate the test signal by the first attenuation range;

34 Use the signal simulation unit 12a to adjust the distribution of the attenuated test signal to N analog signals, so as to simulate the attenuation and delay of the test signal when it is transmitted in N paths;

35 Utilize N antennas 141 to transmit the N analog signals;

36 Make the communication device 142 receive the N analog signals;

37 Obtain a reference value by measuring the signal parameters received by the communication device 142 by the control unit 13a;

38 Switch the communication device 142 to the antenna diversity mode by the control unit 13a, and attenuate the test signal by a second attenuation range, so that the signal parameters received by the communication device 142 are equal to the reference value; and

39. The difference between the first and second attenuation amplitudes is calculated by the control unit 13a, which is the diversity gain of the communication device 142.

Using the control unit 13a to adjust the rotation angle of the turntable 144 can change the direction in which the communication device 142 receives the signal. Repeat steps 31 to 39 for different directions to know the effect of the receiving direction of the communication device 142 on the diversity gain. In addition, the aforementioned signal parameters may be information such as signal strength, signal quality, or data throughput.

FIG. 4 is a flow chart of the operation of measuring antenna diversity gain by using the multipath simulation system 10b of the present invention. In the analog system 10b, although the distributed adjustment method is different from that of the analog system 10a, it does not affect the calculation of the diversity gain. As shown in Figure 4, this process includes the following steps:

41. Set the communication device 142 to a single antenna mode by the control unit 13b;

42 make the signal generating device 11 generate a test signal;

43 Use the signal simulation unit 12b to adjust the distribution of the test signal to N analog signals, so as to simulate the attenuation and delay of the test signal when it is transmitted in N paths;

44 Utilize N antennas 141 to transmit the N analog signals;

45 Make the communication device 142 receive the N analog signals;

46 Obtain a reference value by measuring the signal parameters received by the communication device 142 by the control unit 13b;

47 Switch the communication device 142 to the antenna diversity mode by the control unit 13b, and repeat steps 42 to 46, so that the signal parameters received by the communication device 142 are equal to the reference value; and

48. Select one of the N paths by the control unit 13b, and calculate the difference between the analog signals of the selected path in the single antenna mode and the antenna diversity mode, which is the antenna diversity gain of the communication device 142.

Similarly, the control unit 13b can be used to adjust the rotation angle of the turntable 144 to change the orientation of the communication device 142 for receiving signals, and then repeat steps 41 to 48 to know the influence of the receiving orientation on the diversity gain. Signal parameters are information such as signal strength, signal quality, or data throughput.

It can be understood that, for those of ordinary skill in the art, various other corresponding changes and modifications can be made according to the technical scheme and technical concept of the present invention, and all these changes and modifications should belong to the appended rights of the present invention. the scope of protection required.

Claims (10)

1. A multi-path simulation system, characterized in that it at least includes: a signal generating device for generating a signal; A signal simulation unit, coupled to the signal generating device, adjusts the distribution of the signal to N analog signals, so as to simulate the attenuation and delay of the signal when it is transmitted through N paths, where N is an integer greater than 1; and An anechoic chamber includes N antennas inside, coupled to the signal simulation unit, and used to transmit the N analog signals respectively. 2. The multi-path simulation system according to claim 1, wherein the signal simulation unit comprises: an attenuating device for attenuating the signal to generate an attenuated signal; A power divider, coupled to the attenuation device, distributes the attenuation signal into N sub-attenuation signals; N attenuators, coupled to the power divider, are used to attenuate the N sub-attenuated signals respectively, so as to simulate the attenuation generated when the signals are transmitted on the N paths; and N-1 delay lines are respectively coupled to the N-1 attenuators of the N attenuators to delay the N-1 sub-attenuated signals attenuated by the N-1 attenuators, so as to simulate the signal attenuation in the N-1 attenuators. The respective delays generated during the transmission of the N-1 paths. 3. The multipath simulation system according to claim 2, wherein the attenuation device is a step attenuator. 4. The multi-path simulation system according to claim 1, wherein the signal simulation unit comprises: A power divider, coupled to the signal generating device, divides the signal into N sub-signals; N attenuators, coupled to the power divider, are used to attenuate the N sub-signals, so as to simulate the attenuation of the signals when they are transmitted on the N paths; and N-1 delay lines are respectively coupled to the N-1 attenuators of the N attenuators to delay the N-1 sub-signals attenuated by the N-1 attenuators, so as to simulate the signal at the N-1 attenuators. Delays generated when N-1 paths are transmitted. 5. The multi-path simulation system according to claim 1, wherein the anechoic chamber contains: a communication device for receiving the N analog signals; and A turntable is used to carry the communication device and change the orientation of the communication device. 6. The multi-path analog system according to claim 1, wherein the signal generating device is a vector signal generator. 7. A multi-path simulation method, characterized in that it at least includes: generate a signal; Adjusting the distribution of the signal to N analog signals, so as to simulate the attenuation and delay of the signal when the signal is transmitted in N paths, where N is an integer greater than 1; using N antennas to respectively transmit the N analog signals, wherein the N antennas are located in an anechoic chamber; and A communication device in the anechoic chamber is used to receive the N analog signals. 8. The multi-path simulation method according to claim 7, wherein the signal is generated by a vector signal generator or a selected sample of the communication device. 9. The multi-path simulation method according to claim 7, wherein the step of adjusting the signal distribution comprises: attenuating the signal to produce an attenuated signal; distributing the attenuation signal into N sub-attenuation signals; attenuating the N sub-attenuated signals, so as to simulate the attenuation of the signal when the signal is transmitted on the N paths; and Delaying the N sub-attenuated signals is used to simulate delays generated when the signals are transmitted through the N paths. 10. The multi-path simulation method according to claim 7, wherein the step of adjusting the signal distribution comprises: distribute the signal into N sub-signals; attenuating the N sub-signals, so as to simulate the attenuation of the signal when it is transmitted on the N paths; and Delaying the N sub-signals simulates the respective delays generated when the signals are transmitted through the N paths.

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