System and method for using a single radio frequency (RF) data packet signal receiver to perform time-switched multiple input, multiple output (MIMO) data packet signal analysis

Abstract

A system and method for performing time-switching MIMO signal analysis using a single RF signal receiver to capture multiple incoming data packet signals. According to an exemplary embodiment, a similar portion of the repeat data slot can be captured using a period equal to the period of its primary repeat data frame.

Description

Technical Field

[0001] This invention relates to testing multiple-input multiple-output (MIMO) data packet signal transmitters, and more specifically, to using a single radio frequency (RF) data packet signal receiver to perform time-switched MIMO data packet signal analysis. Prior Technology

[0002] Increasingly, many well-known and widespread data communication systems communicate via digital data signals, where data is distributed across several data packets transmitted sequentially and then reassembled in a receiver. Typically, subsequent transmissions follow various signal paths (e.g., in the case of the Internet). Conventional test equipment used to measure these data signals captures these data packets, stores them, and then transfers them for analysis. Typically, the transfer and analysis of the captured data takes longer than the process of extracting it from the data signal, partly because the captured data needs to be transferred to a remote analysis circuitry system (e.g., a computer separate from the test equipment). Consecutive data packets are usually closely spaced, especially in data signals transmitted at high data rates. Therefore, conventional test equipment typically does not measure consecutive packets, but instead captures non-adjacent packets spaced apart by an interval approximating the time required for analysis or measurement.

[0003] However, it is often desirable to capture consecutive packets, for example, to analyze power changes from one packet to another. To accomplish this with conventional test equipment, it would typically be necessary to increase the time interval used to capture data packets, making the capture window equal to the duration of several consecutive data packets being captured and analyzed. However, this is disadvantageous because increasing the capture window also reduces the overall data capture and analysis operation, as more data needs to be transferred between the capture memory and the analysis engine. Furthermore, in many communication systems, data packets are not tightly spaced, meaning that much of the captured data remains unused due to the gaps between consecutive data packets.

[0004] Furthermore, in multiple-input multiple-output (MIMO) systems with a single data analysis engine, such as those typically performed in production test environments, the time efficiency of capturing and analyzing data packets becomes even more critical. As is well known, MIMO systems use multiple transmitters operating in parallel. Testing one transmitter at a time requires the entire system to remain in an operational transmission state for a longer period, and its performance may be affected due to increased heat buildup. To effectively avoid this, it would be necessary to test one transmitter, disconnect the power supply to that unit, wait for it to stabilize in its off state, and then re-power the unit to test the next transmitter, and so on. Therefore, the overall test time will increase significantly.

[0005] Newer test implementations enable multiple transmitters in a MIMO system to function correctly during test operations and require the use of multiple receivers in the test unit to capture multiple incoming data packet streams for coordinated analysis. However, this results in a significant increase in cost due to the additional data packet receivers and associated synchronization hardware and software. Summary of the Invention

[0006] A system and method for performing time-switched MIMO signal analysis using a single RF signal receiver to capture multiple incoming data packet signals. According to an exemplary embodiment, a similar portion of the repeat data slot can be captured using a period equal to the period of its primary repeat data frame.

[0007] According to an exemplary embodiment, a method for capturing multiple portions of a radiation multiple-input multiple-output (MIMO) data packet signal received via a plurality of signal channels defining a channel matrix includes: receiving a radiation multiple-input multiple-output (MIMO) data packet signal via the plurality of signal channels, wherein the MIMO data packet signal comprises a plurality of data packet streams, each of the plurality of data packet streams comprising a similar plurality of repeating data frames having a similar period, each of the plurality of repeating data frames comprising a similar plurality of repeating data slots, each of the plurality of repeating data slots comprising a similar plurality of data... The plurality of data symbols of a first entity in the plurality of data packet streams include a first reference symbol, and the plurality of data symbols of a second entity in the plurality of data packet streams include a second reference symbol; a first capture of a periodic portion of a plurality of repeating data slots of the first entity in the plurality of data packet streams begins at a first time T1; and a second capture of a periodic portion of a plurality of repeating data slots of the second entity in the plurality of data packet streams begins at a second time T2; wherein a difference between the first time T1 and the second time T2 is equal to the similar period of the plurality of repeating data frames.

[0008] According to another exemplary embodiment, a method for capturing multiple portions of a Radiated Multiple-Input Multiple-Output (MIMO) data packet signal received via a plurality of signal channels defining a channel matrix includes: receiving a control signal having a period; receiving a Radiated Multiple-Input Multiple-Output (MIMO) data packet signal via the plurality of signal channels, wherein the MIMO data packet signal includes a plurality of data packet streams, each of the plurality of data packet streams including a similar plurality of repeating data frames having the period, each of the plurality of repeating data frames including a similar plurality of repeating data slots, wherein the plurality of repeating data slots include Each of the plurality of data packets includes a plurality of similar data symbols, each of the plurality of data symbols of a first entity in the plurality of data packet streams includes a first reference symbol, and each of the plurality of data symbols of a second entity in the plurality of data packet streams includes a second reference symbol; a first capture of a periodic portion of a plurality of repeating data slots of the first entity in the plurality of data packet streams begins at a first time T1; and a second capture of a periodic portion of a plurality of repeating data slots of the second entity in the plurality of data packet streams begins at a second time T2; wherein a difference between the first time T1 and the second time T2 is equal to the period. Simple Explanation of the Diagram

[0009] [Figure 1] Depicts a typical test environment for a MIMO data packet transceiver system. [Figure 2] Depicts the data packet streams transmitted and captured when testing a MIMO data packet transceiver system using typical techniques. [Figure 3] Depicts a test environment for a MIMO data packet transceiver system according to an exemplary embodiment. [Figure 4] depicts the data packet stream transmitted and captured during a test of a MIMO data packet transceiver system according to an exemplary embodiment. Implementation

[0010] The following description refers to exemplary embodiments of the claimed invention as illustrated in the accompanying drawings. These descriptions are intended to be illustrative and not to limit the scope of the invention. These embodiments are described in full detail to enable those skilled in the art to practice the subject matter of the invention, and it will be understood that other embodiments may be practiced with some variations without departing from the spirit and scope of the subject matter of the invention.

[0011] Throughout this disclosure, unless explicitly indicated otherwise herein, it will be understood that the individual circuit elements described may be single or multiple. For example, the terms "circuit" and "circuitry" may include single or multiple components that may be active and / or passive and are connected or otherwise coupled together (e.g., as one or more integrated circuit chips) to provide the described functionality. Additionally, the term "signal" may refer to one or more current, voltage, or data signals. In the drawings, similar or related elements will have similar or related alphanumeric or numerical identifiers. Furthermore, although the invention has been discussed in the context of embodiments using discrete electronic circuit systems (preferably in the form of one or more integrated circuit chips), depending on the frequency or data rate of the signal to be processed, one or more suitable programmable processors may alternatively be used to implement the functionality of any part of this circuit system. Furthermore, in the case where the diagrams depict functional blocks of various embodiments, these functional blocks do not necessarily indicate the division between hardware circuit systems.

[0012] As discussed in more detail below, new systems and methods are introduced for analyzing MIMO signals that require only a single receiver on a multi-port tester. An exemplary embodiment may include two time and frequency synchronization testers that acquire captured MIMO signals from multiple receiving antennas that are virtually close to simultaneous (e.g., during consecutive time intervals closely spaced in time). These MIMO signals can then be analyzed together to reconstruct the underlying data stream. While several solutions exist for analyzing over-the-air (OTA) MIMO signals, all previously known examples require more than one receiver in their implementations, for example, using a time and / or frequency locked vector signal analyzer (VSA).

[0013] Referring to Figure 1, the conventional test environment 10 includes a MIMO transceiver test apparatus (DUT) 20 with multiple (e.g., two in this example, but it should be understood that other M×N MIMO implementations may also be used according to this discussion, where M and N may be equal or unequal) RF data packet signal transmitters 22a, 22b for transmitting their respective MIMO signal components 25a11, 25a12, 25b21, 25b22 via associated antennas 24a, 24b; and a MIMO tester 30 with multiple (e.g., two in this example) RF data packet signal receivers 32a, 32b for receiving their respective MIMO signal components 25a11, 25a12, 25b21, 25b22 via associated antennas 34a, 34b. In the tests performed for this example, the transmission port RF1A of the two testers simulated DUT 20 transmitting in 2×2 MIMO mode (with two dual-port antennas 24a, 24b to establish a hybrid MIMO OTA channel), and the receiving port RF2A of the two other testers acted as testers 30 to capture horizontally polarized (H-POL) and vertically polarized (V-POL) signals for analysis. Mutual time synchronization and / or frequency synchronization of receivers 32a and 32b (and the exchange of captured signal information) can be facilitated via one or more conducted signal connections 33a, 33b between receivers 32a and 32b.

[0014] The medium through which the OTA signal components 25a11, 25a12, 25b21, and 25b22 pass (i.e., the surrounding ambient atmosphere between the DUT 20 and the tester 30) acts as a wireless signal channel, which can be modeled as a signal channel H. Signal channel H is characterized by a hybrid matrix 12 (e.g., a 2×2 matrix in this example of 2×2 MIMO), where the matrix elements h11, h12, h21, and h22 coefficients are used for the individual signal channel characteristics (e.g., the signal path conductivity or loss of the individual signal components 25a11, 25a12, 25b21, and 25b22). This is due to the availability of multiple wireless OTA signal paths, as will be readily understood by those skilled in the art. For example, unlike cable signal environments, in a wireless channel, tester antennas 34a and 34b receive the transmitted DUT signal TX1 (first signal components 25a11 and 25a12), and DUT antennas 24a and 24b transmit TX2 (second signal components 25b21 and 25b22), which are affected by the respective channel H matrix coefficients h11, h12, h21, and h22. Therefore, the received composite DUT signal RX1 (sum of first component signals 25a11 + 25b21) and the RX2 (sum of second component signals 25a12 + 25b22) received and captured by tester antennas 34a and 34b can be characterized as follows: RX1 = h11(t1)*TX1 + h21(t1)*TX2 RX2 = h12(t1)*TX1 + h22(t1)*TX2

[0015] Referring to Figure 2, the signal flow of this test environment 10 can be depicted as shown, where the transmitted signals TX1 and TX2 generate signal components 25a11, 25a12, 25b21, and 25b22, which in this example include frames with a 10-millisecond (ms) interval. Each frame includes 80 (0-79) slots, and each slot further includes 14 (0-13) symbols, of which 12 are data symbols and at least one is a demodulation reference symbol (DMRS). As discussed above, the time and frequency synchronization receiver simultaneously captures its respective received signal streams RX1 (the sum of the first component signals 25a11+25b21) and RX2 (the sum of the second component signals 25a12+25b22) at a desired or otherwise predetermined time t1, and then performs MxN (e.g., 2×2 in this example) MIMO analysis at a subsequent time.

[0016] Referring to Figure 3, the test environment 100 according to an exemplary embodiment includes a MIMO transceiver test apparatus (DUT) 120 having multiple (e.g., two in this example, but it should be understood that other MxN MIMO implementations may also be used according to this discussion, where M and N may be equal or unequal) RF data packet signal transmitters 122a, 122b for transmitting their respective MIMO signal components 125a11, 125a12, 125b21, 125b22 via associated antennas 124a, 124b; and a MIMO tester 130 having multiple (e.g., two in this example) RF data packet signal receivers 132a, 132b for receiving their respective MIMO signal components 125a11, 125a12, 125b21, 125b22 via associated antennas 134a, 134b. In the tests performed for this example, the transmission ports RF1A of the two testers simulated a DUT 120 transmitting in 2×2 MIMO mode (with two dual-port antennas 124a and 124b to establish a hybrid MIMO OTA channel), and the ports RF2A of the two other testers acted as testers 130 to capture horizontally polarized (H-POL) and vertically polarized (V-POL) signals for analysis. In this type of test environment 100, the received composite DUT signal RX1 (the sum of the first component signals 125a11 + 125b21, where its acquisition begins at a first time T1) and RX2 (the sum of the second component signals 125a12 + 125b22, where its acquisition begins at a first time T2) received and captured via tester antennas 134a and 134b can be characterized as follows: RX1 = h11(t1)*TX1 + h21(t1)*TX2 RX2 = h12(t2)*TX1 + h22(t2)*TX2

[0017] In the tests performed in this exemplary embodiment of the "time switching" test environment 100, the transmission ports RF1A of two testers simulate the DUT 120 (with two dual-port antennas 124a and 124b to establish a hybrid MIMO OTA channel (e.g., transmitting on the left and receiving on the right of the diagram) transmitting in 2×2 MIMO mode) and the receiving ports RF2A and RF3A of another single tester 130 to capture H-POL and V-POL signals for analysis. As mentioned above and discussed in more detail below, mutual time synchronization and / or frequency synchronization of receivers 132a and 132b is not required.

[0018] Referring to Figure 4, the signal flow of this test environment 100 can be depicted as shown, where the transmitted signals TX1 and TX2 generate signal components 125a11, 125a12, 125b21, and 125b22, which in this example (where mu=3 and SCS=120kHz) include frames with 10-millisecond (ms) intervals. Each frame includes 80 (0-79) slots, and each slot then includes 14 (0-13) symbols, of which 12 are data symbols and at least one is a demodulation reference symbol (DMRS). However, significant differences include that the transmitted signals TX1 and TX2 have different data sequences with a duration of 10 ms, repeat these different data sequences at a 10 ms period, and have different DMRS antenna port configurations. Further differences include that the received signals RX1 and RX2 are received sequentially by the same receiver at intervals separated by multiples of the same 10 ms period and with the minimum delay between the capture triggers (in 10 ms increments) to ensure pseudo-stillness. Therefore, a 10 ms timer with a period of 10 ms can be configured on the tester 130 to ensure that the same segment of the repeating 10 ms frame in the two received signals RX1 and RX2 is captured for analysis.

[0019] When a pseudo-static state is established as mentioned above, the channel parameters h11, h12, h21, and h22 should not change significantly during the 10ms interval between two acquisitions. Similarly, DUT defects (such as frequency errors or timing drift between transmitters 122a and 122b) across this short time interval should be very similar (although both such parameters can be measured and compensated during analysis). Some measurements (e.g., timing alignment errors) should even be improved by implementing this method, because the amount of timing error accumulated by the internal timer across such a short time interval (e.g., 10 ms) should be much smaller than the amount of timing error incurred by the conventional cross-triggered method across multiple testers. (Note that although this example uses a 10 ms timer, other timer values ​​can be used, such as 1 ms, as long as the acquisition timings of the transmission signals TX1 and TX2 repeat with the same period, such as 1 ms).

[0020] Therefore, it is easy to understand from these two examples that in the conventional test environment 10 (Figure 1), the received signals RX1 and RX2 are captured by different receivers 32a and 32b, but the two captures begin at time t1. In contrast, in the time-switching test environment 100 (Figure 3), the received signals RX1 and RX2 are captured by receivers 132a and 132b present in the common tester 130, but the first signal RX1 is captured at time t1 and the second signal RX2 is captured at time t2.

[0021] Based on the foregoing discussion, it can be seen that the present invention provides a cost-reducing method for analyzing MIMO signals using a single receiver, which can span the time switching of multiple MIMO streams in a time and frequency synchronized manner. Previous solutions required multiple synchronization receivers.

[0022] Additionally, it can improve various measurements, such as time alignment error (TAE), because the distributed VSA architecture of a typical MIMO configuration can cause triggering and / or sampling delays between data packets.

[0023] Various other modifications and variations to the structure and operation of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. Although the invention has been described in conjunction with specific preferred embodiments, it should be understood that the invention claimed should not be unduly limited to these specific embodiments. The following claims are intended to define the scope of the invention and thereby cover the structures and methods within the scope of these claims and their equivalents.

[0024] 10: Testing Environment 12: Mixed Matrix 20: Test Equipment (DUT) 22a, 22b: Transmitters 24a, 24b: Antenna 25a11, 25a12, 25b21, 25b22: Signal components 30: Tester 32a, 32b: Receiver 33a, 33b: Conducted signal connection 34a, 34b: Antenna 100: Test Environment 120: Test Equipment (DUT) 122a, 122b: Transmitters 124a, 124b: Antenna 125a11, 125a12, 125b21, 125b22: Signal components 130: MIMO Tester 132a, 132b: Receiver 134a, 134b: Antenna H: Signal Channel

Claims

1. A method for capturing a portion of a radiated multiple-input multiple-output (MIMO) data packet signal, comprising: receiving the radiated MIMO data packet signal via a plurality of signal channels, wherein the radiated MIMO data packet signal includes a plurality of data packet streams, at least two of the plurality of data packet streams being based on different channel coefficients, each of the plurality of data packet streams including a similar plurality of repeating data frames having a similar period, each of the plurality of repeating data frames including a similar plurality of repeating data slots arranged in sequence, each of the plurality of repeating data slots including a similar plurality of data symbols; initiating a first capture of a first period portion of one of the plurality of repeating data slots of a first of the plurality of data packet streams at a first time T1; and initiating a second capture of a second period portion of one of the plurality of repeating data slots of a second of the plurality of data packet streams at a second time T2; The first period portion includes a first set of data slots, the second period portion includes a second set of data slots, and the first set of data slots and the second set of data slots are identical data slots arranged in sequence in the first and second of the plurality of data packet streams, respectively.

2. The method of request 1, wherein the similar plurality of data symbols comprises a similar plurality of repeating data symbols.

3. The method of claim 1, wherein each of the plurality of data symbols of the first in the plurality of data packet streams includes a first reference symbol; wherein each of the plurality of data symbols of the second in the plurality of data packet streams includes a second reference symbol; and wherein the first reference symbol and the second reference symbol are orthogonal to each other.

4. The method of claim 1, further comprising: measuring the similar period of the plurality of repeating data frames; generating a control signal having the similar period of the plurality of repeating data frames; and initiating at least the first capture and the second capture in response to the control signal.

5. The method of claim 1, further comprising calculating an evaluation channel matrix based on the first fetch period portion and the second fetch period portion of at least the plurality of repeating data slots and at least the first reference symbol and the second reference symbol.

6. A method for capturing a portion of a radiated multiple-input multiple-output (MIMO) data packet signal, comprising: receiving a control signal having a period; receiving the radiated MIMO data packet signal via a plurality of signal channels, wherein the radiated MIMO data packet signal includes a plurality of data packet streams, at least two of the plurality of data packet streams being based on different channel coefficients, each of the plurality of data packet streams including a similar plurality of repeating data frames having the period, each of the plurality of repeating data frames including a similar plurality of repeating data slots arranged in sequence, each of the plurality of repeating data slots including a similar plurality of data symbols; initiating a first capture of a first period portion of one of the plurality of repeating data slots of a first of the plurality of data packet streams at a first time T1; and initiating a second capture of a second period portion of one of the plurality of repeating data slots of a second of the plurality of data packet streams at a second time T2; The first period portion includes a first set of data slots, the second period portion includes a second set of data slots, and the first set of data slots and the second set of data slots are identical data slots arranged in sequence in the first and second of the plurality of data packet streams, respectively.

7. The method of claim 6, wherein the similar plurality of data symbols comprises a similar plurality of repeating data symbols.

8. The method of claim 6, wherein each of the plurality of data symbols of the first in the plurality of data packet streams includes a first reference symbol; wherein each of the plurality of data symbols of the second in the plurality of data packet streams includes a second reference symbol; and wherein the first reference symbol and the second reference symbol are orthogonal to each other.

9. The method of claim 6, further comprising calculating an evaluation channel matrix based on the first fetch period portion and the second fetch period portion of at least the plurality of repeating data slots and at least the first reference symbol and the second reference symbol.

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