KR20160018573A - System and method for testing radio frequency wireless signal transceivers using wireless test signals - Google Patents

Abstract

A system and method for performing a wireless test of a radio frequency (RF) signal transceiver (DUT) device. Multiple antennas in a shielded enclosure containing a DUT may be used to capture multiple radio frequency RF test signals originating from RF test signals copied from the DUT and to determine the signal power level of each of the multiple radio frequency RF test signals, The signal phase of each of the multiple wireless RF test signals of the plurality of wireless RF test signals, and the signal power level of the combination of the received signals. This phase control of the captured wireless RF test signal is performed separately for any DUTs being tested in the shielded enclosure to provide compensation for the multipath signal environment within the shielded enclosure, regardless of the location of the DUT, ≪ / RTI > simulates a wired test signal path during a wireless test of the wireless network.

Description

TECHNICAL FIELD [0001] The present invention relates to a system and a method for a radio frequency wireless signal transceiver using a wireless test signal,

The present invention relates to testing of radio frequency (RF) radio signal transceivers, and more particularly to testing such devices without RF signal cables for the delivery of RF test signals.

Many of today's electronic devices use wireless technology for both connection and communication purposes. Because wireless devices transmit and receive electromagnetic energy and two or more wireless devices are likely to interfere with each other's operation due to their signal frequency and power spectral density, the wireless technology of these devices and their devices is subject to various radio technology standards .

When designing such devices, engineers specifically note that each of the above-described standards-based specifications of the wireless technology contained in the devices satisfies or exceeds those devices. In addition, when these devices are subsequently manufactured in large quantities, these devices are tested to ensure that the manufacturing defects do not cause improper operation, including those devices that are compliant with the wireless technology standards-based specifications contained in the devices do.

For testing of these devices following manufacture and assembly of these devices, current wireless device test systems ("testers") employ subsystems that analyze signals received from each device. Such subsystems generally include a vector signal generator (VSG) that provides at least a source signal to be transmitted to the device, and a vector signal analyzer (VSA) for analyzing the signal produced by the device. The generation of test signals by the VSG and the signal analysis performed by the VSA are generally programmable to be used to test various devices according to various wireless technology standards while varying the frequency range, bandwidth and signal modulation characteristics .

The calibration and performance verification tests of the DUT are typically performed using an electrically conductive signal path, such as an RF cable, rather than a radio signal path, whereby the DUT and the tester communicate via electromagnetic radiation. Thus, the signal between the tester and the DUT is not copied through the ambient space, but through the conductive signal path. The use of this conductive signal path ensures repeatability and consistency of measurement and eliminates the positioning and directionality of the (transmitting and receiving) DUT as a factor in signal propagation.

For multiple input and multiple output (MIMO) DUTs, the signal path must be provided in some form for each input / output connection of the DUT. For example, for a MIMO device intended to operate with three antennas, three conductive signal paths, for example cables and connections, must be provided for testing.

However, using the conductive signal path significantly affects the time required for each DUT test due to the need to physically connect and disconnect the cable between the DUT and the tester. In addition, in the case of a MIMO DUT, multiple such connection and disconnection actions must be performed both at the beginning and at the end of the test. Additionally, since the signals passed during the test are not copied over the surrounding space, when they are normally used as intended and the antenna assembly for the DUT is not in use during this test, this test does not simulate real-world motion , Any performance characteristics that can be contributed to the antenna are not reflected in the test results.

Alternatively, the test may be performed using a test signal delivered via electromagnetic radiation rather than conduction through the cable. This does not require the connection and disconnection of the task cable, which will have the benefit of reducing the test time associated with such connection and disconnection. However, the "channel" through which the radiated signal and receiver antenna escape, i.e., the surrounding space through which the test signal is transmitted and received, uniquely originates elsewhere and causes signal interference due to other electromagnetic signals penetrating into the surrounding space, . Such a signal may be received by the DUT antenna and may include multipath signals from each interfering signal source due to signal reflections. Thus, the "state" of a " channel " will generally degrade compared to using a separate conductive signal path such as, for example, a cable for each antenna connection.

One way to prevent, or at least significantly reduce, interference from such external signals is to isolate the radiation signal interface to the DUT and the tester using a shielded enclosure. However, such enclosures generally fail to produce comparable measurement accuracy and repeatability. This is especially true for smaller enclosures than the smallest anechoic chambers. In addition, these enclosures have a sensitive tendency not only for the reinforcement and destructive interference of multipath signals generated within these enclosures, but also for the positioning and orientation of DUTs.

It is therefore desirable to have a system and method for testing a wireless signal transceiver, particularly a wireless MIMO signal transceiver, wherein a radiating electromagnetic test signal is used to prevent interference signals due to an external generated signal and multipath signal effects, And simulate real-world system behavior while avoiding the test time required to connect and disconnect the test wiring while maintaining accuracy.

In accordance with the present invention, the system and method provide for performing a wireless test of a radio frequency (RF) signal transceiver device under test (DUT). Multiple antennas in a shielded enclosure containing a DUT may be used to capture multiple radio frequency RF test signals originating from RF test signals copied from the DUT and to determine the signal power level of each of the multiple radio frequency RF test signals, The signal phase of each of the multiple wireless RF test signals of the plurality of wireless RF test signals, and the signal power level of the combination of the received signals. This phase control of the captured wireless RF test signal is performed separately for any DUTs being tested in the shielded enclosure to provide compensation for the multipath signal environment within the shielded enclosure, regardless of the location of the DUT, ≪ / RTI > simulates a wired test signal path during a wireless test of the wireless network.

In accordance with one embodiment of the present invention, a system for performing a wireless test of a radio frequency (RF) signal transceiver device under test (DUT) comprises:

A structure defining an inner region and an outer region, the structure being configured to permit placement of the DUT within the inner region and substantially shield from electromagnetic radiation originating from the outer region;

A plurality of antennas at least partially disposed within the inner region to receive at least one plurality of wireless RF test signals associated with a common RF test signal copied from the DUT; And

An RF signal control circuit coupled to the plurality of antennas,

Controlling each phase of at least a portion of the at least one plurality of wireless RF test signals to provide at least one plurality of phase control RF test signals in accordance with the at least one phase control signal;

By measuring and combining the at least one plurality of phase control RF test signals to provide an RF output signal and one or more phase control signals associated with the combination of the at least one plurality of phase control RF test signals,

The RF signal control circuit responsive to the at least one plurality of wireless RF test signals;

.

According to another embodiment of the present invention, a method of performing a wireless test of a radio frequency (RF) signal transceiver device under test (DUT) comprises:

Providing a structure that defines an inner region and an outer region, the structure being configured to permit placement of the DUT within the inner region and substantially shield from electromagnetic radiation generated from the outer region;

Providing a plurality of antennas at least partially disposed within the inner region to receive at least one plurality of wireless RF test signals associated with a common RF test signal copied from the DUT; And

Responsive to at least one plurality of wireless RF test signals,

Controlling each phase of at least a portion of the at least one plurality of wireless RF test signals to provide at least one plurality of phase control RF test signals in accordance with the at least one phase control signal;

By measuring and combining the at least one plurality of phase control RF test signals to provide an RF output signal and one or more phase control signals associated with the combination of the at least one plurality of phase control RF test signals,

Responsive to the at least one plurality of wireless RF test signals;

.

Figure 1 illustrates a general operation and possible test environment for a wireless signal transceiver.
Figure 2 shows a test environment for a wireless signal transceiver using a conductive test signal path.
3 shows a test environment for a MIMO wireless signal transceiver using a conductive signal path and a channel model for such a test environment.
Figure 4 shows a test environment for a MIMO wireless signal transceiver using copied electromagnetic signals and a channel model for such a test environment.
5 illustrates a test environment according to an exemplary embodiment in which a MIMO DUT can be tested using a copied electromagnetic test signal.
Figure 6 illustrates a test environment in which a DUT is tested using a radiated electromagnetic test signal within a shielded enclosure.
Figures 7 and 8 illustrate an exemplary embodiment of a test environment in which a wireless DUT is tested using a copied electromagnetic test signal within a shielded enclosure while reducing multipath effects.
Figure 9 illustrates a physical representation of a shielded enclosure in accordance with an exemplary embodiment for use in the test environment of Figures 7 and 8;
10 illustrates a test environment in accordance with an exemplary embodiment in which a DUT can be tested using a radiated electromagnetic test signal.
Figure 11 shows another test environment according to an exemplary embodiment in which the DUT can be tested using a radiative electromagnetic test signal.
Figure 12 illustrates an exemplary algorithm for testing a DUT using the test environment of Figure 11;
Figure 13 illustrates another test environment in accordance with an exemplary embodiment in which the DUT can be tested using radiative electromagnetic test signals.
Figure 14 illustrates an exemplary algorithm for testing a DUT using the test environment of Figure 13;
Figure 15 shows another test environment according to an exemplary embodiment in which the DUT can be tested using a radiative electromagnetic test signal.
FIG. 16 illustrates an exemplary algorithm for testing a DUT using the test environment of FIG.
Figure 17 shows a test signal transmitted by the DUT for a defined frequency range before compensation according to an exemplary embodiment.
Figure 18 shows the swept signal of Figure 17 before and after compensation in accordance with an exemplary embodiment with exemplary phase shift values for the test environments of Figures 10, 11, 13, and 15.
19 illustrates an exemplary algorithm for performing the compensation shown in FIG.
20 illustrates another test environment for testing a wireless DUT while compensating using multiple test signal phase shifts in accordance with an exemplary embodiment.
Figure 21 illustrates the test environment of Figure 20, which adds test signal gain adjustment to compensate in accordance with a further exemplary embodiment.

The following detailed description is an exemplary embodiment of the invention with reference to the accompanying drawings. This description is illustrative of the scope of the invention and is not intended to be limiting thereof. It will be appreciated that these embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and that other embodiments may be practiced with some modifications without departing from the scope or spirit of the invention.

It will be understood that throughout this specification, individual circuit elements as described may be singular or plural, unless explicitly contradicted by context. For example, terms such as " circuit "and" circuitry "may include either a single component or a plurality of components, which may be active and / or passive, As one or more integrated circuit chips). Additionally, the term "signal" refers to one or more currents, one or more voltage or data signals. Within the figures, similar or related elements will have similar or related character, number or alphanumeric directives. Additionally, although the invention has been described in terms of an implementation that utilizes discrete electronic circuitry (preferably in the form of one or more integrated circuit chips), the function of any portion of such circuitry, depending on the signal frequency or the data rate to be processed, Or alternatively may be implemented using one or more appropriately programmed processors. Further, to the extent that the figures illustrate the diagrams of the functional block diagrams of the various embodiments, the functional blocks do not necessarily indicate the division between hardware circuits.

Referring to FIG. 1, the general operating environment for a wireless signal transceiver and the ideal test environment (at least in terms of simulating real-world operation) comprise a tester 100 and the DUT 200 communicates wirelessly. In general, some forms of test controller 10 (e.g., a personal computer) may also be used to exchange test instructions and data with tester 100 and DUT 200 via wired signal interfaces 11a and 11b Will be used. The tester 100 and the DUT 200 each have one antenna 102 and one antenna 202 for the MIMO device and each of them includes a conductive signal connector 104 and 204 (e.g., , Many types known in the art). The test signals (source and response) are transmitted wirelessly between the tester 100 and the DUT 200 via the antennas 102, 202. For example, during the transmission (TX) test of the DUT 200, the electromagnetic signal 203 is copied from the DUT antenna 202. Depending on the directionality of the antenna emission pattern, this signal 203 is copied in a number of directions to bring incident signal component 203i and reflected signal component 203r received by the tester antenna 102. As noted above, these reflected signal components 203r, as well as other electromagnetic signals (not shown) that have originated elsewhere, as well as products of multipath signal effects, have both augmented signal interference and canceled signal interference, Prevent repeatable signal reception and test results.

2, a conductive signal path, such as RF coaxial cable 106, is used to provide a continuous, reliable, and reliable signal path for the transmission of a test signal between the tester 100 and the DUT 200 to prevent such unreliable test results. And is used to connect the tester 100 and the antenna connectors 104, 204 of the DUT 200 to provide a repeatable electrically conductive signal path. However, as described above, this increases the overall test time due to the time required to connect and disconnect the cable 106 before and after testing.

Referring to FIG. 3, the additional test time for connecting and disconnecting the test cable may be longer in the MIMO DUT 200a test. In this case, multiple test cables 106 may be coupled to the RF test signal from the RF signal source 110 (e.g., VSG) in the tester 100a for receipt by the RF signal receiver 210 in the DUT 200a. It is required to connect the corresponding tester 104 and the DUT 204 connector to enable transmission. For example, in a typical test environment, a tester for MIMO device testing may include a corresponding one or more RF test signals 111a, 111b, ..., 111n (e.g., having variable signal power, 110b,..., 110n to provide a packet data signal (e.g. These corresponding test cables 106a, 106b, ..., 106n, which are connected through respective testers 104a, 104b, ..., 104n and through the DUTs 204a, 204b, 211b, ..., 211n for the corresponding RF signal receivers 210a, 201b, ..., 210n in the DUT 200a. Therefore, the additional test time required to connect and disconnect these test cables 106 can be increased by a factor n, which corresponds to the number of test cables 106.

As described above, using a test cable to connect the tester 100a and the DUT 200a has the advantage of providing a continuous, reliable, repeatable test connection. These test connections 107 may be modeled as a signal channel H characterized by a diagonal matrix 20 where the diagonal matrix elements 22 are each associated with a respective signal channel characteristic For example, a direct-coupled coefficient (h ₁₁ , h ₂₂ , ..., h _aa (h _ij , where h _ij , i = j)).

Referring to FIG. 4, in accordance with one or more exemplary embodiments, a conductive or wired channel 107 (FIG. 3) includes a wireless channel 106a corresponding to the wireless signal interface 106a between the tester 100a and the DUT 200a 107) a). As described above, the tester 100a and the DUT 200a communicate the test signals 111 and 211 through the array of antennas 102 and 202, respectively. In this type of test environment, the signal channel 107a is no longer represented by the diagonal matrix 20, but instead is represented by one or more non-zero cross-coupled coefficients 24a, 24b ) (h _ij , where i ≠ j). As will be readily appreciated by those skilled in the art, this is due to the multiple radio signal paths available in channel 107a. For example, unlike a cabled signal environment in which each DUT connector 204 ideally only receives signals from its corresponding tester connector 104, in such a wireless channel 107a, The antenna 202a is connected to the test antenna 102a by the tester antennas 102a, 102b, ..., 102n corresponding to the channel matrix coefficients h ₁₁ , h ₁₂ , ..., h _1n , .

According to a known principle, the coefficient h of the channel matrix H corresponds to the characteristic of the channel 107a affecting the transmission and reception of the RF test signal. Collectively, these coefficients h define the channel state number k (H), which is the product of the norm of the H matrix and the inverse of the H matrix as indicated by the following equation product:

Factors affecting these coefficients can change the channel state number in such a way as to produce a measurement error. For example, in degraded channels, small errors can produce large errors in the test results. If the channel number is low, a small error in the channel can yield a small measurement at the receive (RX) antenna. However, when the channel number is high, a small error in the channel may lead to a large measurement error at the receiving antenna. This channel state number k (H) is also sensitive to the physical positioning and orientation of the DUT within its environment (e.g., a shielded enclosure) and the orientation of its various antennas 204. Thus, the probability of repeatable and accurate test results will be low, even though there is no external interference signal arriving at or through the reflection and collision on receive antenna 204 or at any location.

Referring to FIG. 5, in accordance with one or more exemplary embodiments, the test signal interface between the tester 100a and the DUT 200a may be wireless. The DUT 200a is located in the interior 301 of the shielded enclosure 300. This shielding enclosure 300 may be implemented as a metal enclosure, for example, similar to or at least effective for a Faraday cage construction. Which isolates the DUT 200a from the copied signal originating from the outer region 302 of the enclosure 300. [ According to an exemplary embodiment, the geometry of the enclosure 300 allows it to function as a closed end waveguide.

For example, multiple (n) antenna arrays 102a, 102b, ..., 102n are disposed at any location, such as in or on the opposing inner surface 302 of enclosure 300, 103b, ..., 103n (described further below) generated from the test signal sources 110a, 110b, ..., 110n in the tester 100a. Each antenna array includes multiple (M) antenna elements. For example, the first antenna array 102a includes m antenna elements 102aa, 102ab, ..., 102am. Each of these antenna elements 102aa, 102ab, ..., 102am is driven by respective phase controlled RF test signals 131aa, 131ab, ..., 131am provided by respective RF signal control circuits 130a .

As shown in the example of the first RF signal control circuit 130a, the RF test signal 111a from the first RF test signal source 110a is increased in size by the signal size control circuit 132 For example, amplified) or reduced (e.g., attenuated). The resulting size control test signal 133 is replicated by the signal duplication circuit 134 (e.g., a signal distributor). The resulting size controlled replica RF test signals 135a, 135b, ..., 135m are sized to drive the antenna elements 102aa, 102ab, ..., 102am of the antenna array 102a and phase control signals 131aa, 136b, ..., 136m to control the respective signal phases of the respective phase control circuits 136a, 136b,.

The remaining antenna arrays 102b, ..., 102n and their respective antenna elements are driven in the same manner by the corresponding RF control circuits 130b, ..., 130m. This is transmitted to the antennas 202a, 202b, ..., 202n of the DUT 200a according to a channel matrix H as described above, and a composite number of composite radiation signals 103a, 103b , ..., 103n. DUT 200a processes one or more of the received test signals 211a, 211b, ..., 211m and one or more feedback signals (e.g., magnitude, relative phase, etc.) 201a. These feedback signals 201a are provided to the control circuit 138 in the RF signal control circuit 130. [ This control circuit 138 provides control signals 137, 139a, 139b, ..., 139m for the magnitude control circuit 132 and the phase control circuit 136. [ Thus, a closed loop control path is provided to enable gain and phase control of the individual radiation signals from the tester 100a for reception by the DUT 200a.

In accordance with known channel optimization techniques, the control circuitry 138 may be configured to minimize the channel state number (k (H)) and produce a received signal having approximately the same magnitude as measured at each DUT antenna 202 This feedback data 201a from the DUT 200a is used to achieve the optimal channel condition by changing the magnitude and phase of the radiated signal in the same manner. This will create a communication channel that produces a test result that is substantially similar to the test result that the radiation signal passes through and uses a conductive signal path (e.g., an RF signal cable).

Following this successive transmission and channel state feedback events, this operation by the control circuitry 138 of the RF signal control circuit 130 is repeated for each antenna < RTI ID = 0.0 > Will change the signal magnitude and phase for the arrays 102a, 102b, ..., 102n. Once this optimized channel state number k (H) is achieved, the corresponding size and phase settings are maintained and the tester 100a and the DUT 200a are then in the order of testing as if performed in a wired test environment I will continue.

In practice, the reference DUT may be deployed as a test fixture in the shielded enclosure 300 for use in optimizing the channel condition through the repetitive process described above. Then, since the path loss differences experienced in the controlled channel environment of the enclosure 300 must be within normal test tolerances, additional DUTs of the same design can be tested continuously without having to perform channel optimization in all examples.

Referring to FIG. 5, for example, the initial transmission is modeled to yield a channel state number of 13.8 db, and the magnitudes of the h ₁₁ and h ₂₂ coefficients are -28 db and -28.5 db, respectively. The size matrix for channel H will be denoted as:

After the above-described repeated magnitude and phase adjustment, the channel state number k (H) is reduced to 2.27 db, and the amplitudes of the h ₁₁ and h ₂₂ coefficients are -0.12 db and -0.18 db, respectively, Calculate the channel size matrix:

These results are comparable to those of a wired test environment, indicating that these wireless test environments can provide test results with similar accuracy. By eliminating time for connection and disconnection of the wire signal path and by including time reduction for gain and phase adjustment in the calculation, the total received signal test time is significantly reduced.

Referring to FIG. 6, the effect of the multipath signal effect on the channel state can be better understood. As described above, when placed in the interior 301 of the enclosure 300, the DUT 200 copies the electromagnetic signals 203a from each antenna 202a during the transmission test. The signal 203a includes components 203b and 203c that radiate away from the antenna 102a of the tester 100a to the outside. However, these signal components 203b and 203c are reflected from the inner surfaces 304 and 306 of the enclosure 300 and arrive as reflected signal components 203br and 203cr, 203ai. ≪ / RTI > As described above, depending on the enhancement and cancellation nature of the interference, the test results tend to be unreliable and inaccurate for use in the overall calibration and performance verification as a whole.

Referring to Figure 7, according to an exemplary embodiment, RF absorbers 320a and 320b are disposed on reflective surfaces 304 and 306. [ As a result, the reflected signal components 203br, 203cr are significantly attenuated to produce less interference with the main incident signal component 203ai, reinforcing or canceling.

Additional RF signal control circuitry 150 may be included for use between the enclosure 300a and the interior 301 of the tester 100a or between the antenna array 102a mounted on the internal surface 302. The additional control circuitry 150 may be included as part of the tester 100a). Radiation signals arriving on the antenna elements 102aa, 102ab, ..., 102am may be provided by the control system 156 Controlled by a phase control circuit 152 having phase control elements 152a, 152b, ..., 152m controlled according to one or more phase control signals 157a, 157b, ..., 157m (103aa, 103ab, ..., 103am) having respective signal phases. The resulting phase control signal 153 is combined in the signal combiner 154 to provide a received signal 155a for the tester 100a and a feedback signal 155b for the control system 156. [ The control system 156 may control the phase of each of the composite received signals 103aa, 103ab, ..., 103am to minimize the apparent signal path loss associated with the internal region 301 of the enclosure 300a, And processes this feedback signal 155b as part of the loop control network. This closed loop control network also allows the system to reset the enabled phased array by these antenna 102a and phase control circuitry 152 when the positioning or orientation of the DUT 200a changes within the enclosure 300a do. As a result, subsequent to minimizing path loss using this feedback loop, it is achieved to accurately and repeatably deliver the DUT signal 203a to the tester 100a using the radiation signal environment within the enclosure 300a .

Referring to FIG. 8, similar controls and remedies for producing accurate and repeatable test results can be achieved for a DUT receive signal test. In this case, the test signal 111a provided by the tester 100a is replicated by the signal combiner / splitter 154 and each phase of the replicated test signal 153 is coupled to the antenna elements 102aa, 102ab, ..., 102am, before being copied. As in the previous case, the reflected signal components 103br, 103cr are significantly attenuated and result in the reinforcement and destructive interference with the main incident signal component 103ai being reduced. One or more feedback signals 203a from the DUT 200a control the information needed to control the phase of the replicated test signal 153 to minimize the apparent signal path loss associated with the interior 301 of the enclosure 300a System 156 to establish a continuous and repeatable signal path loss condition.

Referring to Fig. 9, in accordance with one or more exemplary embodiments, shielded enclosure 300b may be implemented substantially as shown. As discussed above, the DUT includes an enclosure 300b (not shown) that includes an interior surface 301b that includes or faces an interior surface 302 on which the tester antenna arrays 102a, 102b, ..., 102n ) Of the inner portion (301) of the base (301). There is an inner region 301a between which the waveguide cavity surrounded by the RF absorbent material 320 is formed.

As described above and further below, exemplary embodiments of systems and methods enable cable-free testing of wireless DUTs while compensating for multipath effects and optimizing control of signal path loss. do. The multiple antennas used in conjunction with the control system as well as the antenna array can be used to provide a test signal that is provided to the antenna element in a manner such as to emulate a stable and repeatable signal path loss environment normally associated with a conductive signal path environment utilizing the radiation signal environment within the shielded enclosure. To allow phase adjustment. Although the time required for phase shifter adjustment is part of the overall test time, this adjustment time is significantly smaller than the time required to connect and disconnect the test cable, Provide benefits.

In addition, as described further below, the exemplary embodiment may be configured to have a bandwidth such as a signal of 160 MHz (MHz) width as specified by the Institute of Electrical and Electronic Engineers (IEEE) standard 802.11ac For example, a conductive signal path, such as a test cable, to provide non-wire testing of the wireless DUT while achieving test accuracy and repeatable measurement corresponding to the test. By adjusting the phase of the test signal provided to the antenna element, a substantially flat signal response can be generated for the received wide bandwidth signal within the shielded test enclosure. When the individual test signal phases driving the individual antenna elements are adjusted to produce this flat signal response environment, testing using a wide bandwidth signal can be processed without further adjustment as if it were in a wired test environment. Although positioning of the DUT in the shielded enclosure can affect the flatness of the channel response, this positioning sensitivity is within the measurement tolerance defined by the underlying signal standard (e.g., IEEE 802.11ac) It is known.

Additionally, in accordance with an exemplary embodiment, such non-wire testing can be performed on multiple DUTs simultaneously within the same shielded enclosure. The low-crosstalk signal environment of the conductive signal path can be emulated using the radiation test signal environment in the shielded enclosure, with appropriate control and adjustment of the phase and magnitude of the test signal driving the multiple antenna elements. If the phase and gain (or attenuation) of the test signal driving the antenna element is adjusted according to the illustrative embodiment, the signal received at the antenna of the multiple DUT will correspond to the received signal using the wire signal path. For example, this can be achieved by maximizing the direct coupling coefficient (e.g., producing a difference of at least 10 decibels between the direct coupling coefficient and the cross-coupling coefficient) while minimizing the cross-coupling coefficient of the channel matrix.

Referring to FIG. 10, in accordance with an exemplary embodiment, a DUT 200a is positioned within a shielded enclosure 300 for transmission signal testing. The DUT test signal 203a transmitted via the antenna 202a is received by the multiple antenna elements 102a, 102b, ..., 102n. The resulting received signals 105a, 105b, ..., 105n have their respective signal phases controlled and adjusted by respective phase control circuits 236a, 236b, ..., 236n.

In accordance with some exemplary embodiments, the resulting phase control test signals 237a, 237b, ..., 237n are communicated to the control system 242 (described further below) and the signal combining circuit 234. Control system 242 provides phase control signals 243a, 243b, ..., 243n for phase control circuits 236a, 236b, ..., 236n. The combined (e.g., summed) phase control test signals 237a, 237b, ..., 237n yield a composite test signal 235 for downstream analysis by, for example, a VSA (not shown) .

In accordance with another embodiment, phase control test signals 237a, 237b, ..., 237n are combined in signal combiner 234 to produce composite test signal 235. [ The composite test signal 235 is passed to an alternative control system 244 (described further below) which then generates the phase control signals 245a, 246b, ..., 236n for the phase control circuits 236a, 236b, 245b, ..., 245n.

Referring to FIG. 11, in accordance with one exemplary embodiment, in-line control system 242 may use a power measurement to measure the power level of each of phase control test signals 237a, 237b, ..., 237n Circuits 242aa, 242ab, ..., 242an. The resulting power measurement signals 243aa, 243ab, ..., 243an, which represent the respective test signal power levels, are provided to a control circuit 242b, for example in the form of a digital signal processor (DSP) This provides appropriate phase control signals 243ba, 243bb, ..., 243bn for the phase control circuits 236a, 236b, ..., 236n.

Referring to FIG. 12, in accordance with an exemplary embodiment, operation 410 of the test environment of FIG. 11 may proceed as illustrated. First, phase shifters 236a, 236b, ..., 236n are initialized (411), for example, where all phase shift values are set to a common reference phase value or an individual reference phase value. Next, the power levels of the phase control signals 237a, 237b, ..., 237n are measured (412). The measured power values are then summed (413) and the accumulated measured signal power is compared to the previous accumulated measured signal power (414). If the current cumulative measured power is greater than the previous cumulative measured power, then the current phase shift value and cumulative measured power are stored 415, followed by the stored value to the desired reference (e.g., 0.0 > 416). ≪ / RTI > If this criterion is met, adjustment of the test signal phase is terminated (417). Otherwise, adjustment of the test signal phase continues.

Similarly, if the current accumulated measured power is not greater than the previous accumulated measured power (414), adjustment of the test signal continues. Therefore, the phase shifters 236a, 236b, ..., and 236n can receive the received test signals 105a, 105b, ..., and 236n in accordance with a Genetic Algorithm (GA) or Particle Swarm Algorithm (PSA) , 105n (418) to provide another combination or permutation of the phase shift values. Following this, the measurement of power 412, summation 413, and comparison 414 are repeated until the desired criterion is met.

13, an alternative downstream control system 244 (FIG. 10) includes a power measurement circuit 244a (e.g., VSA) and a control circuit 244b DSP). The power level of the composite signal 235 is measured by the power measurement circuit 244a, which provides power measurement data 245a to the control circuit 244b. Control circuit 244b then provides appropriate phase control signals 245ba, 245bb, ..., 245bn to phase shifters 236a, 236b, ..., 236n.

Referring to FIG. 14, operation 420 of the test environment of FIG. 13 may proceed as illustrated. First, the phase shifters 236a, 236b, ..., 236n are initialized 421 by being preset to one or more respective phase shift values. Next, the power level of the composite signal 235 is measured (422), followed by the currently measured power (423) with the previously measured power level. If the currently measured power level is greater than the previous measured power level, the current phase deviation value and the measured power are stored 424 and a determination is made whether the desired reference (e.g., the maximum measured power level) (425). If so, phase adjustment ends (426). Otherwise, the phase adjustment continues.

Similarly, if the currently measured power is not greater than the previous measured power, the phase adjustment continues. Thus, the phase shifters 236a, 236b, ..., 236n are configured to receive the received test signals 105a, 105b, ..., 105n according to an optimization algorithm (e.g., a genetic algorithm GA or a particle swarm algorithm PSA) Lt; RTI ID = 0.0 > a < / RTI > set of phase shift values.

Referring to Figure 15, in-line control system 242 (Figure 10) includes phase detection circuits 242ca, 242cb, ..., 242cn and control circuit 242d For example, DSP). The phase detection circuits 242ca, 242cb ... 242cn detect the respective signal phases of the phase control circuits 237a, 237b, ..., 237n and output the corresponding phase data 243ca, 243cb, ..., 243cn. Based on this data, control circuit 242d provides appropriate phase control signals 243da, 243db, ..., 243dn for phase shifters 236a, 236b, ..., 236n.

Referring to FIG. 16, operation 430 of the test environment of FIG. 15 may proceed as shown. First, phase shifters 236a, 236b, ..., 236n are initialized (431) by being presented with one or more respective phase shift values. Next, the phase of each of the phase controlled signals 237a, 237b, ..., 237n is measured 432 (e.g., for a common or reference signal phase).

Next, based on the measured test signal phase, the phase adjustment of the phase shifters 236a, 236b, ..., 236n is set according to the optimized phase shift value (433). Following this, the power level of the composite signal 235 is measured 434 to confirm the attainment of the desired composite signal power level, followed by phase adjustment (435).

Referring to FIG. 17, there is shown a schematic diagram of an embodiment of the present invention, which has been copied from the DUT 200a at a constant power from a wideband antenna 202a that provides a good response for frequencies in the 700 to 6000 MHz range in the shielded enclosure 300 (e.g., An exemplary received signal 203 appears substantially as shown. As will be readily appreciated, the power profile of the signal will not be flat due to the abundant multi-path signal environment present in the shielded enclosure 300. In the case of packet data signals communicated in accordance with the IEEE standard 802.11ac, the 160 MHz wide frequency band of 5000 to 5160 MHz is of particular interest. As shown, within this frequency band 511, the received signal exhibits a power change of about 25 decibels (dB), as seen in the expanded portion 510 of the signal 203 profile. In accordance with an exemplary embodiment, there is a multiple phase shifter for phase control of a test signal that drives multiple antenna elements, using a test environment as described above, such that the profile is substantially flat for the frequency band of interest 511 As shown in FIG.

Referring to FIG. 18, in accordance with one exemplary embodiment, this may be accomplished using multiple (e.g., sixteen) antenna elements 102 and corresponding phase shifters 236. For example, it is possible to achieve an optimal flat response state 523 using an optimization algorithm (described further below) and using only quadrature adjustments of 0, 90, 180 and 270 degrees. As shown, prior to compensation, the response profile 522 varies by more than 5 dB during the 160 MHz bandwidth 511 of the exemplary test signal. Additionally, when the antenna array is optimized for the power level at the center frequency of 5080 MHz, as shown in top profile 521, the received signal variation is still about 5 dB. However, when the multiphase adjusting devices 236a, 236b, ..., 236n are properly adjusted, it is possible to achieve a response profile 523 that changes only by 0.5dB, even though it is limited only to quadrature adjustment.

Referring to Fig. 19, the compensation shown in Fig. 18 can be achieved using process 440 as shown. First, a number of frequencies within a desired signal bandwidth are defined (441), followed by a first set of phase shift values for a phase shifter (442). The phase shifter is then set to this defined phase value (443) and the power at each frequency is measured (444). Next, the difference between the measured powers in the multiple pairs of defined frequencies is computed (445) and the evaluation of the function (F), which is the same as the difference between the defined maximum power difference and the summed difference of the computed powers, (446).

If the current computed function F _current is greater than the previous computed function F _old , then the phase value is maintained 448 and if the desired condition is met (e.g., the maximum computed function F has been achieved (449). If so, the phase adjustment is terminated (450). If not, the phase adjustment continues. Similarly, if the currently computed function F _current is not greater than the previous computed function F _old , the phase adjustment continues. Step 444 of resolving the phase difference, step 444, power measurement step 444, power difference calculation step 445, and computing the calculated function F, 451, ). This phase adjustment is continued. This process is repeated 449 until the condition is met.

20, similar compensation may be achieved in the context of a cross-coupled signal within shielded enclosure 300 when performing non-wire testing of multiple wireless DUTs, in accordance with an exemplary embodiment. Two DUTs 200a and 200b may be tested using two antenna arrays 235a and 235b but it will be readily appreciated that a different number of DUTs and antenna arrays may also be used. It will be readily understood that what is shown here as individual "DUT 200a, 200b" can be a respective receiver in a single MIMO DUT 200. As described above, a signal source (e.g., (VSG) 110 may use a signal splitter 234 to provide a replica test signal 235 for phase shifting using multiple phase shifters 231 to drive the antenna element 102 of the antenna array 235 Test gods It provides 111. These antenna arrays 235a and 235b provide radiated signal components 103aa, 103ab, 103ba, and 103bb that correspond to the direct coupling and cross-coupling coefficients of the channel matrix H (e.g., as described above). These signal components 103aa, 103ab 103ba, and 103bb are received by the antennas 202a and 202b of the DUTs 200a and 200b. The received signal data 201a and 201b are provided by a DUT 200a and 200b to a control system 206 (e.g., a DSP) which in turn is coupled to the antenna elements 102aa and 102b of the antenna arrays 235a and 235b. 207bp for the phase shifters 236aa, ..., 236am, 236ba, ..., 236bm to control the phase of the signals copied from the phase shifters 210a, ..., Lt; / RTI >

By repeatedly adjusting the phase of the radiation signal, the direct coupled channel matrix (H) coefficients 103aa, 103ba are maximized and the cross-coupling coefficients 103ab, 103bb are minimized (as described above, for example, The coefficient is ideally 10 dB less than the direct coupling factor.)

21, in accordance with another exemplary embodiment, the control system 206 controls the magnitude of the test signals 111a, 111b that are replicated for transmission to the DUT 200a, 200b, , 207bg). ≪ / RTI > This signal magnitude may be controlled by controlling a signal gain stage (e.g., a variable gain amplifier or signal attenuator) 232a, 232b. This may advantageously provide for further optimization of the relative sizes of the direct coupling coefficients 103aa, 103ba and the cross coupling coefficients 103ab, 103bb of the channel matrix H. For example, the size of the direct coupling coefficients 103aa, 103ba can be normalized while still maintaining sufficient attenuation (e.g., 10 dB or more) of the cross coupling coefficients 103ab, 103bb.

Various other modifications and variations in the structure and method of operation of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the invention is not to be unduly limited to such specific embodiments. The following claims define the scope of the invention and are intended to cover structures and methods within the scope of these claims and their equivalents.

Claims (18)

An apparatus comprising a system for performing a wireless test of a radio frequency (RF) signal transceiver device under test (DUT) comprising:
A structure defining an inner region and an outer region, the structure being configured to permit placement of the DUT within the inner region and substantially shield from electromagnetic radiation originating from the outer region;
A plurality of antennas at least partially disposed within the inner region to receive at least one plurality of wireless RF test signals associated with a common RF test signal copied from the DUT; And
An RF signal control circuit coupled to the plurality of antennas,
Controlling each phase of at least a portion of the at least one plurality of wireless RF test signals to provide at least one plurality of phase control RF test signals in accordance with the at least one phase control signal;
By measuring and combining the at least one plurality of phase control RF test signals to provide the RF output signal and the at least one phase control signal associated with the combination of the at least one plurality of phase control RF test signals,
The RF signal control circuit responsive to the at least one plurality of wireless RF test signals;
(RF) signal transceiver device under test (DUT), characterized in that it comprises a system for performing a radio test of a radio frequency (RF) signal transceiver device under test (DUT). The RF signal control circuit according to claim 1, wherein the RF signal control circuit comprises:
A phase control circuit coupled to the plurality of antennas and responsive to the at least one plurality of wireless RF test signals and the at least one phase control signal by providing the at least one plurality of phase control RF test signals;
A control signal circuit coupled to the phase control circuit and responsive to the at least one phase control RF test signal by providing the at least one phase control signal; And
A coupling circuit coupled to at least one of the phase control circuit and the control signal circuit and responsive to the at least one plurality of phase control RF test signals by providing the RF output signal;
(RF) signal transceiver device under test (DUT), characterized in that it comprises a system for performing a radio test of a radio frequency (RF) signal transceiver device under test (DUT). 3. The apparatus of claim 2, wherein the control signal circuit comprises a power detection circuit. ≪ Desc / Clms Page number 13 > 3. The apparatus of claim 2, wherein the control signal circuit comprises:
A power measurement circuit responsive to said at least one plurality of phase control RF test signals by providing a plurality of power signals representative of respective power levels of respective ones of said at least one plurality of phase control RF test signals; And
A processing circuit coupled to the power measurement circuit and responsive to the plurality of power signals by providing the at least one phase control signal;
(RF) signal transceiver device under test (DUT), characterized in that it comprises a system for performing a radio test of a radio frequency (RF) signal transceiver device under test (DUT). 3. The apparatus of claim 2, wherein the control signal circuit comprises a phase detection circuit. ≪ Desc / Clms Page number 13 > 3. The apparatus of claim 2, wherein the control signal circuit comprises:
A phase measurement circuit responsive to the at least one plurality of phase control RF test signals by providing a plurality of phase signals representative of respective signal phases of each of the at least one plurality of phase control RF test signals; And
A processing circuit coupled to the phase measurement circuit and responsive to the plurality of phase signals by providing the at least one phase control signal;
(RF) signal transceiver device under test (DUT), characterized in that it comprises a system for performing a radio test of a radio frequency (RF) signal transceiver device under test (DUT). The RF signal control circuit according to claim 1, wherein the RF signal control circuit comprises:
A phase control circuit coupled to the plurality of antennas and responsive to the at least one plurality of wireless RF test signals and the at least one phase control signal by providing the at least one plurality of phase control RF test signals;
A coupling circuit coupled to the phase control circuit and responsive to the at least one plurality of phase control RF test signals by providing the RF output signal; And
A control signal circuit coupled to the coupling circuit and the phase control circuit and responsive to the RF output signal by providing the at least one phase control signal;
(RF) signal transceiver device under test (DUT), characterized in that it comprises a system for performing a radio test of a radio frequency (RF) signal transceiver device under test (DUT). 8. The apparatus of claim 7, wherein the control signal circuit comprises a power detection circuit. ≪ Desc / Clms Page number 13 > 8. The circuit of claim 7, wherein the control signal circuit comprises:
A power measurement circuit responsive to said RF output signal by providing a power signal indicative of a power level of said RF output signal; And
A processing circuit coupled to the power measurement circuit and responsive to the power signal by providing the at least one phase control signal;
(RF) signal transceiver device under test (DUT), characterized in that it comprises a system for performing a radio test of a radio frequency (RF) signal transceiver device under test (DUT). A method of performing a wireless test of a radio frequency (RF) signal transceiver (DUT) device comprising:
Providing a structure that defines an inner region and an outer region, the structure being configured to permit placement of the DUT within the inner region and substantially shield from electromagnetic radiation generated from the outer region;
Providing a plurality of antennas at least partially disposed within the inner region to receive at least one plurality of wireless RF test signals associated with a common RF test signal copied from the DUT; And
Responsive to the at least one plurality of wireless RF tests,
Controlling each phase of at least a portion of the at least one plurality of wireless RF test signals to provide at least one plurality of phase control RF test signals in accordance with the at least one phase control signal;
By measuring and combining the at least one plurality of phase control RF test signals to provide the RF output signal and the at least one phase control signal associated with the combination of the at least one plurality of phase control RF test signals,
Responsive to the at least one plurality of wireless RF test signals;
(RFT) signal transceiver device (DUT) according to claim 1, characterized in that the radio frequency (RF) signal transceiver device (DUT) 11. The method of claim 10,
Wherein the controlling comprises responding to the at least one plurality of wireless RF test signals and the at least one phase control signal by providing the at least one plurality of phase control RF test signals,
The measurement and combination
Measuring the at least one plurality of phase control RF test signals to provide the at least one phase control signal, and
Combining the at least one plurality of phase control RF test signals to provide the RF output signal;
(RFT) signal transceiver device (DUT) according to claim 1, characterized in that the radio frequency (RF) signal transceiver device (DUT) 12. The method of claim 11, wherein measuring the at least one plurality of phase control RF test signals comprises detecting at least one power of the at least one plurality of phase control RF test signals. A method for performing a radio test of a frequency (RF) signal transceiver device under test (DUT). 12. The method of claim 11, wherein measuring the at least one plurality of phase control RF test signals comprises:
Detecting at least one power of the at least one plurality of phase control RF test signals to provide a plurality of power signals representative of respective power levels of each of the at least one plurality of phase control RF test signals; And
Processing the plurality of power signals to provide the at least one phase control signal;
(RFT) signal transceiver device (DUT) according to claim 1, characterized in that the radio frequency (RF) signal transceiver device (DUT) 12. The method of claim 11, wherein measuring the at least one plurality of phase control RF test signals comprises detecting at least one phase of the at least one plurality of phase control RF test signals A method for performing a radio test of a radio frequency (RF) signal transceiver (DUT) device. 12. The method of claim 11, wherein measuring the at least one plurality of phase control RF test signals comprises:
Detecting at least one phase of the at least one plurality of phase control RF test signals to provide a plurality of phase signals representative of respective signal phases of each of the at least one plurality of phase control RF test signals; And
Processing the plurality of phase signals to provide the at least one phase control signal;
(RFT) signal transceiver device (DUT) according to claim 1, characterized in that the radio frequency (RF) signal transceiver device (DUT) 11. The method of claim 10,
Wherein the controlling comprises responding to the at least one plurality of wireless RF test signals and the at least one phase control signal by providing the at least one plurality of phase control RF test signals,
The measurement and combination
Combining the at least one plurality of phase control RF test signals to provide the RF output signal; and
Measuring the RF output signal to provide the at least one phase control signal,
(RFT) signal transceiver device (DUT) according to claim 1, characterized in that the radio frequency (RF) signal transceiver device (DUT) 17. The method of claim 16, wherein measuring the RF output signal to provide the at least one phase control signal comprises detecting power of the RF output signal. A method for performing a wireless test of a test device (DUT). 17. The method of claim 16, wherein measuring the RF output signal to provide the at least one phase control signal comprises:
Detecting a power of the RF output signal to provide a power signal indicative of a power level of the RF output signal; And
Processing the power signal to provide the at least one phase control signal;
(RFT) signal transceiver device (DUT) according to claim 1, characterized in that the radio frequency (RF) signal transceiver device (DUT)

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