Measurement of radio frequency signal propagation conditions

Abstract

A method for determining cellular signal characteristics includes receiving and recording a plurality of cellular signal data at one of a plurality of locations in an environment. The method may also include identifying one or more individual cellular signals received at one of the plurality of locations based at least in part on the plurality of cellular signal data. The method may also include determining one or more cellular signal characteristics for each of one or more individual cellular signals received at one of the plurality of locations based at least in part on the plurality of cellular signal data. The method may also include simulating one or more individual cellular signals at one of the plurality of locations in the environment based at least in part on the one or more cellular signal characteristics.

Description

Technical Field

[0001] This disclosure relates to systems and methods for characterizing radio frequency (RF) propagation conditions and determining the characteristics of cellular signals. Background Technology

[0002] To enhance occupant awareness and convenience, vehicles may be equipped with vehicle communication systems configured to transmit and receive cellular signals from cellular base stations. The performance of these systems can be affected by radio frequency (RF) propagation conditions in the vehicle's surrounding environment. RF propagation conditions can vary significantly across different locations in the environment due to a variety of factors. For example, RF propagation conditions in densely populated urban areas may be characterized by a low signal-to-noise ratio (SNR) due to electromagnetic interference. In another example, RF propagation conditions in rural or remote areas may be characterized by low signal strength and high latency due to long transmission distances. Current systems and methods used for the design, testing, and validation of vehicle communication systems may not account for the varying RF propagation conditions and cellular signal characteristics at different locations throughout the environment.

[0003] Therefore, while vehicle communication systems and methods have achieved their intended purpose, a new and improved system and method is still needed to characterize radio frequency (RF) propagation conditions for vehicles and determine RF characteristics. Summary of the Invention

[0004] According to several aspects, a method for determining cellular signal characteristics is provided. The method may include receiving and recording multiple cellular signal data at one of a plurality of locations in an environment. The multiple cellular signal data includes cellular signals received at one of the plurality of locations in the environment. The method may further include identifying one or more individual cellular signals received at one of the plurality of locations based at least in part on the multiple cellular signal data. The method may further include determining one or more cellular signal characteristics of each of the one or more individual cellular signals received at one of the plurality of locations based at least in part on the multiple cellular signal data. The method may further include simulating one or more individual cellular signals at one of the plurality of locations in the environment based at least in part on the one or more cellular signal characteristics of each of the one or more individual cellular signals received at one of the plurality of locations.

[0005] In another aspect of this disclosure, receiving and recording multiple cellular signal data may further include using a survey vehicle to pass through multiple locations. The survey vehicle is equipped with a survey antenna array and a Global Navigation Satellite System (GNSS). Receiving and recording multiple cellular signal data may further include continuously receiving and recording multiple cellular signal data using the survey antenna array. Receiving and recording multiple cellular signal data may further include continuously determining and recording multiple vehicle positions using GNSS. Receiving and recording multiple cellular signal data may further include aligning a subset of the multiple cellular signal data with each of the multiple locations, at least in part, based on the multiple vehicle positions.

[0006] In another aspect of this disclosure, identifying one or more individual cellular signals may further include determining the ambient noise floor based at least in part on multiple cellular signal data. Identifying one or more individual cellular signals may further include using receive beamforming to identify one or more regions of interest in the environment with energy higher than the ambient noise floor, based at least in part on multiple cellular signal data. Identifying one or more individual cellular signals may further include using receive beamforming to locate each of the one or more individual cellular signals within one or more regions of interest.

[0007] In another aspect of this disclosure, identifying one or more regions of interest may further include spatially scanning multiple cellular signal data using a first beam having a first beamwidth to identify one or more regions of interest.

[0008] In another aspect of this disclosure, locating each of one or more individual cellular signals may further include spatially scanning each of one or more regions of interest using a second beam having a second beamwidth. The second beamwidth is smaller than the first beamwidth.

[0009] In another aspect of this disclosure, determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the direction of arrival of each of the one or more individual cellular signals. Determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the amplitude of each of the one or more individual cellular signals. Determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the phase of each of the one or more individual cellular signals. Determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the time of arrival of each of the one or more individual cellular signals.

[0010] In another aspect of this disclosure, determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining identification metadata about each of the one or more individual cellular signals. The identification metadata provides at least information about the base station that initiated each of the one or more individual cellular signals.

[0011] In another aspect of this disclosure, determining the identification metadata may further include determining identification metadata for each of one or more individual cellular signals. The identification metadata includes at least one of the following: cell identifier (cellID), system information block (SIB), master information block (MIB), and service set identifier (SSID).

[0012] In another aspect of this disclosure, the method may further include identifying which of the one or more individual cellular signals is a multipath signal based at least in part on one or more cellular signal characteristics of each of the one or more individual cellular signals.

[0013] In another aspect of this disclosure, simulating one or more individual cellular signals may also include reproducing each of the one or more individual cellular signals in an anechoic chamber containing a test vehicle.

[0014] According to several aspects, a system for determining cellular signal characteristics is provided. The system may include a measurement system comprising a measurement antenna array mounted on a measurement vehicle and a measurement controller electrically communicating with the measurement antenna array. The measurement controller is programmed to receive multiple cellular signal data using the measurement antenna array. The multiple cellular signal data includes cellular signals received in the environment.

[0015] In another aspect of this disclosure, the system may further include a test system comprising a test controller. The test controller is programmed to receive multiple cellular signal data from a measurement system. The test controller is also programmed to use receive beamforming, at least in part, based on the multiple cellular signal data, to identify one or more regions of interest in the environment having energy higher than the ambient noise floor. The test controller is further programmed to use receive beamforming to locate each of one or more individual cellular signals within the one or more regions of interest. The test controller is also programmed to determine one or more cellular signal characteristics of each of the one or more individual cellular signals, at least in part, based on the multiple cellular signal data.

[0016] In another aspect of this disclosure, to identify one or more individual cellular signals, the test controller is further programmed to determine the ambient noise floor based at least in part on multiple cellular signal data. To identify one or more individual cellular signals, the test controller is also programmed to spatially scan the multiple cellular signal data using a first beam having a first beamwidth, to identify one or more regions of interest in the environment with energy higher than the ambient noise floor based at least in part on the multiple cellular signal data using receive beamforming. To identify one or more individual cellular signals, the test controller is further programmed to spatially scan each of the one or more regions of interest using a second beam having a second beamwidth, to locate each of the one or more individual cellular signals within the one or more regions of interest using receive beamforming. The second beamwidth is smaller than the first beamwidth.

[0017] In another aspect of this disclosure, in order to determine one or more cellular signal characteristics of each of the one or more individual cellular signals, the test controller is also programmed to determine the direction of arrival of each of the one or more individual cellular signals. In order to determine one or more cellular signal characteristics of each of the one or more individual cellular signals, the test controller is also programmed to determine the amplitude of each of the one or more individual cellular signals. In order to determine one or more cellular signal characteristics of each of the one or more individual cellular signals, the test controller is also programmed to determine the phase of each of the one or more individual cellular signals. In order to determine one or more cellular signal characteristics of each of the one or more individual cellular signals, the test controller is also programmed to determine the time of arrival of each of the one or more individual cellular signals.

[0018] In another aspect of this disclosure, in order to determine one or more cellular signal characteristics of each of the one or more individual cellular signals, the test controller is also programmed to determine identification metadata about each of the one or more individual cellular signals. The identification metadata provides at least information about the base station that initiated each of the one or more individual cellular signals.

[0019] In another aspect of this disclosure, in order to determine the identification metadata, the test controller is also programmed to determine identification metadata for each of one or more individual cellular signals. The identification metadata includes at least one of the following: cell ID, System Information Block (SIB), Master Information Block (MIB), and Service Set Identifier (SSID).

[0020] In another aspect of this disclosure, the test system may further include an anechoic chamber and one or more transmitting antenna arrays electrically communicating with a test controller and disposed within the anechoic chamber. The test controller is also programmed to reproduce each of one or more individual cellular signals within the anechoic chamber using the one or more transmitting antenna arrays. A test vehicle is housed within the anechoic chamber.

[0021] According to several aspects, a method for determining cellular signal characteristics is provided. The method may include using a measuring vehicle to traverse multiple locations in an environment. The measuring vehicle is equipped with a measuring antenna array and a Global Navigation Satellite System (GNSS). The method may further include continuously receiving and recording multiple cellular signal data using the measuring antenna array. The multiple cellular signal data includes cellular signals received at one of multiple locations in the environment. The method may further include continuously determining and recording multiple vehicle positions using GNSS. The method may further include aligning a subset of the multiple cellular signal data with each of the multiple locations, at least partially based on the multiple vehicle positions. The method may further include identifying one or more individual cellular signals received at one of the multiple locations, at least partially based on the multiple cellular signal data. The method may further include determining one or more cellular signal characteristics of each of the one or more individual cellular signals received at one of the multiple locations, at least partially based on the multiple cellular signal data.

[0022] In another aspect of this disclosure, identifying one or more individual cellular signals may further include determining the ambient noise floor based at least in part on multiple cellular signal data. Identifying one or more individual cellular signals may further include spatially scanning the multiple cellular signal data using a first beam having a first beamwidth to identify one or more regions of interest in the environment with energy higher than the ambient noise floor, based at least in part on the multiple cellular signal data, using receive beamforming. Identifying one or more individual cellular signals may further include spatially scanning each of the one or more regions of interest using a second beam having a second beamwidth to locate each of the one or more individual cellular signals within the one or more regions of interest using receive beamforming.

[0023] In another aspect of this disclosure, determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the direction of arrival of each of the one or more individual cellular signals. Determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the amplitude of each of the one or more individual cellular signals. Determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining the phase of each of the one or more individual cellular signals. Determining one or more cellular signal characteristics of each of the one or more individual cellular signals may further include determining identification metadata about each of the one or more individual cellular signals. The identification metadata provides at least information about the base station that initiated each of the one or more individual cellular signals.

[0024] Further areas of application will become apparent from the description provided herein. It should be understood that these descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0025] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0026] Figure 1 This is a schematic diagram of a measurement system for measuring cellular signals according to an exemplary embodiment;

[0027] Figure 2 This is a schematic diagram of a test system for testing a test vehicle according to an exemplary embodiment; and

[0028] Figure 3 This is a flowchart of a method for determining cellular signal characteristics according to an exemplary embodiment. Detailed Implementation

[0029] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its uses.

[0030] In various aspects of this disclosure, radio frequency (RF) propagation conditions can vary considerably between different locations in the environment due to a variety of factors. For example, RF propagation conditions in densely populated urban areas may be characterized by numerous reflections and multipath signals caused by obstacles in the environment, such as large buildings. In another example, RF propagation conditions in rural or remote areas may be characterized by low signal strength and high latency due to long transmission distances. This disclosure provides a novel and improved system and method for measuring and recording RF propagation conditions in a variety of different environments, enabling the re-creation of realistic RF propagation conditions in controlled settings for the testing and development of wireless systems.

[0031] Reference Figure 1 A measurement system for measuring cellular signals is shown and is generally indicated by reference numeral 10a. The measurement system 10a is shown together with a measurement vehicle 12a. Although a passenger vehicle is shown, it should be understood that the measurement vehicle 12a can be any type of vehicle without departing from the scope of this disclosure. The measurement system 10a generally includes a measurement controller 14, a measurement antenna array 16, and a Global Navigation Satellite System (GNSS) 18.

[0032] Measurement controller 14 is used to implement a method 100 for determining cellular signal characteristics, as described below. Measurement controller 14 includes at least one processor 20 and a non-transitory computer-readable storage device or medium 22. Processor 20 may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among a plurality of processors associated with measurement controller 14, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally a device for executing instructions.

[0033] Computer-readable storage device or medium 22 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is persistent or non-volatile memory that can be used to store various operational variables when the processor 20 is powered off. Computer-readable storage device or medium 22 may be implemented using multiple storage devices, such as programmable read-only memory (PROM), electrical PROM (EPROM), electrically erasable PROM (EEPROM), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which represents executable instructions used by the measurement controller 14 to control various systems of the measurement vehicle 12a.

[0034] The measurement controller 14 may also consist of multiple controllers that are electrically communicating with each other. The measurement controller 14 may interconnect with additional systems and / or controllers of the vehicle 12a, allowing the measurement controller 14 to access data, such as measuring the speed, acceleration, braking, and steering angle of the vehicle 12a.

[0035] The measurement controller 14 communicates electrically with the measurement antenna array 16 and the GNSS 18. In an exemplary embodiment, electrical communication is established using, for example, a CAN network, a FLEXRAY network, a local area network (e.g., WiFi, Ethernet, etc.), a Serial Peripheral Interface (SPI) network, etc. It should be understood that various additional wired and wireless technologies and communication protocols used for communicating with the measurement controller 14 are within the scope of this disclosure. It should also be understood that, within the scope of this disclosure, electrical communication also includes the transfer of power and / or energy between electrical devices (e.g., using wires and / or wireless power transmission technologies).

[0036] The measurement antenna array 16 is used to receive radio frequency (RF) signals from the environment 24 surrounding the measurement vehicle 12a. In a non-limiting example, the measurement antenna array 16 is configured to receive cellular network signals, such as 2G, 3G, 4G, 5G, 6G, etc. In an exemplary embodiment, the measurement antenna array 16 includes multiple antenna elements of different types, designs, and / or functional principles. In a non-limiting example, the measurement antenna array 16 includes one or more monopole antennas. In another non-limiting example, the measurement antenna array 16 includes one or more dipole antennas. It should be understood that the measurement antenna array 16 may include any number, type, and / or configuration of antennas without departing from the scope of this disclosure. It should also be understood that the measurement antenna array 16 may also include additional signal processing components, such as filters, amplifiers, receiver modules, etc., in electrical communication with the multiple antenna elements.

[0037] In one exemplary embodiment, the measurement antenna array 16 is disposed on the outer surface of the measurement vehicle 12a, such as the roof, trunk, doors, and / or windows of the measurement vehicle 12a. In another exemplary embodiment, the measurement antenna array 16 is disposed on the inner surface of the measurement vehicle 12a, such as the headliner, dashboard, doors, and / or windows of the measurement vehicle 12a. In some examples, the measurement antenna array 16 is temporarily fixed to the measurement vehicle 12a. In one exemplary embodiment, the measurement antenna array 16 is configured to have omnidirectional receiving capability to receive signals from all directions relative to the measurement vehicle 12a. In a non-limiting example, the measurement controller 14 is configured to simultaneously sample each of the plurality of antenna elements of the measurement antenna array 16 and store the RF signal data received by the measurement antenna array 16 for further processing, as will be discussed in more detail below. The measurement antenna array 16 is in electrical communication with the measurement controller 14, as described above.

[0038] GNSS 18 is used to determine the geographic location of the measurement vehicle 12a. In one exemplary embodiment, GNSS 18 is a Global Positioning System (GPS). In a non-limiting example, the GPS includes a GPS receiver antenna (not shown) and a GPS controller (not shown) in electrical communication with the GPS receiver antenna. The GPS receiver antenna receives signals from multiple satellites, and the GPS controller calculates the geographic location of the measurement vehicle 12a based on the signals received by the GPS receiver antenna. In one exemplary embodiment, GNSS 18 also includes a map. The map includes information about infrastructure, such as city boundaries, roads, railways, sidewalks, buildings, etc. Therefore, the map information is used to contextualize the geographic location of the measurement vehicle 12a. In one non-limiting example, the map is retrieved from a remote source using a wireless connection. In another non-limiting example, the map is stored in a database of GNSS 18. It should be understood that various additional types of satellite-based radio navigation systems, such as the Global Positioning System (GPS), Galileo Satellite Navigation System, GLONASS, and BeiDou Navigation Satellite System (BDS), are all within the scope of this disclosure. GNSS 18 is in electrical communication with the measurement controller 14, as described above.

[0039] Reference Figure 2 A test system for testing a test vehicle 12b is shown and is generally indicated by reference numeral 10b. The test system 10b is shown together with the test vehicle 12b. Although a passenger vehicle is shown, it should be understood that the test vehicle 12b can be any type of vehicle without departing from the scope of this disclosure. The test system 10b typically includes a test controller 30, an anechoic chamber 32, and one or more transmitting antenna arrays 34.

[0040] Test controller 30 is used to implement a method 100 for determining cellular signal characteristics, as described below. Test controller 30 includes at least one processor 36 and a non-transitory computer-readable storage device or medium 38. Processor 36 may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among a plurality of processors associated with test controller 30, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally a device for executing instructions.

[0041] Computer-readable storage device or medium 38 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operational variables when the processor 36 is powered off. Computer-readable storage device or medium 38 may be implemented using multiple storage devices, such as programmable read-only memory (PROM), electrical PROM (EPROM), electrically erasable PROM (EEPROM), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which represents executable instructions.

[0042] Test controller 30 may also consist of multiple controllers that communicate electrically with each other. Test controller 30 communicates electrically with one or more transmit antenna arrays 34. In an exemplary embodiment, electrical communication is established using, for example, a CAN network, a FLEXRAY network, a local area network (e.g., WiFi, Ethernet, etc.), a Serial Peripheral Interface (SPI) network, etc. It should be understood that various additional wired and wireless technologies and communication protocols used for communicating with test controller 30 are within the scope of this disclosure. It should also be understood that, within the scope of this disclosure, electrical communication also includes the transfer of power and / or energy between electrical devices (e.g., using wires and / or wireless power transmission technologies).

[0043] Anechoic chamber 32 is used to provide a controlled RF environment for testing test vehicle 12b. In one exemplary embodiment, anechoic chamber 32 is an RF anechoic chamber coated with radiation-absorbing material (RAM) 40. RAM 40 is configured to effectively absorb incident RF radiation to mitigate and / or eliminate reflections of RF signals within anechoic chamber 32. In a non-limiting example, RAM 40 comprises a pyramid-shaped polyurethane foam block loaded with conductive carbon material. In some examples, anechoic chamber 32 also includes a Faraday cage (not shown) to mitigate the intrusion of ambient RF noise into anechoic chamber 32.

[0044] One or more transmitting antenna arrays 34 are used to generate RF signals within an anechoic chamber 32 to test the test vehicle 12b. In one exemplary embodiment, at least one of the one or more transmitting antenna arrays 34 is a phased array comprising a plurality of antenna elements that generate a radio beam that can be electronically manipulated (i.e., beamforming) without physical movement of the one or more transmitting antenna arrays 34. In another exemplary embodiment, at least one of the one or more transmitting antenna arrays 34 includes a directional or omnidirectional antenna element having actuators for realizing physical movement or aiming of the antenna element. In a non-limiting example, the one or more transmitting antenna arrays 34 are configured to be controlled by a test controller 30 to generate any arbitrary RF environment within the anechoic chamber 32, including signals effectively originating from any location within the anechoic chamber 32, for example.

[0045] In one exemplary embodiment, one or more transmitting antenna arrays 34 are disposed within an anechoic chamber 32. In another exemplary embodiment, one or more transmitting antenna arrays 34 are disposed outside the anechoic chamber 32 and RF signals are injected into the anechoic chamber 32 using waveguides. Although Figure 2 Two transmit antenna arrays 34 are shown; however, it should be understood that the test system 10b may include any number of transmit antenna arrays 34 disposed within the anechoic chamber 32. In a non-limiting example, the test system 10b includes transmit antenna arrays 34 disposed at multiple heights within the anechoic chamber 32 (e.g., one transmit antenna array 34 at each of the six corners of a rectangular chamber). One or more transmit antenna arrays 34 are in electrical communication with the test controller 30, as described above.

[0046] Continue to refer to Figure 2 The test vehicle 12b has a test vehicle system 50. In an exemplary embodiment, the test vehicle system 50 includes a test vehicle controller 52 and a test vehicle communication system 54.

[0047] The test vehicle controller 52 is used to control the test vehicle communication system 54, as described below. The test vehicle controller 52 includes at least one processor 56 and a non-transitory computer-readable storage device or medium 58. The processor 56 may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among a plurality of processors associated with the test vehicle controller 52, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally a device for executing instructions.

[0048] Computer-readable storage device or medium 58 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operational variables when the processor 56 is powered off. Computer-readable storage device or medium 58 may be implemented using multiple storage devices, such as programmable read-only memory (PROM), electrical PROM (EPROM), electrically erasable PROM (EEPROM), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which represents executable instructions used by the test vehicle controller 52 to control various systems of the test vehicle 12b.

[0049] The test vehicle controller 52 may also consist of multiple controllers that are electrically communicating with each other. The test vehicle controller 52 may interconnect with additional systems and / or controllers of the test vehicle 12b, allowing the test vehicle controller 52 to access data such as the speed, acceleration, braking, and steering angle of the test vehicle 12b.

[0050] The test vehicle controller 52 communicates electrically with the test vehicle communication system 54. In an exemplary embodiment, electrical communication is established using, for example, a CAN network, a FLEXRAY network, a local area network (e.g., WiFi, Ethernet, etc.), a Serial Peripheral Interface (SPI) network, etc. It should be understood that various additional wired and wireless technologies and communication protocols used for communicating with the test vehicle controller 52 are within the scope of this disclosure. It should also be understood that, within the scope of this disclosure, electrical communication also includes the transfer of power and / or energy between electrical devices (e.g., using wires and / or wireless power transmission technologies).

[0051] The test vehicle communication system 54 is used by the test vehicle controller 52 to communicate with other systems outside the test vehicle 12b. For example, the test vehicle communication system 54 includes the ability to communicate with vehicles (“V2V” communication), infrastructure (“V2I” communication), remote systems at remote call centers (e.g., General Motors’ ON-STAR), and / or personal devices. Generally, the term “vehicle-to-everything communication” (“V2X” communication) refers to communication between the test vehicle 12b and any remote system (e.g., vehicles, infrastructure, and / or remote systems).

[0052] In some embodiments, the test vehicle communication system 54 is a wireless communication system configured to communicate using the IEEE 802.11 standard or via a wireless local area network (WLAN) using cellular data communication (e.g., using GSMA standards, such as SGP.02, SGP.22, SGP.32, etc.). Therefore, the test vehicle communication system 54 may also include an embedded universal integrated circuit card (eUICC) configured to store at least one cellular connectivity profile, such as an embedded subscriber identity module (eSIM) profile.

[0053] The test vehicle communication system 54 is also configured to communicate via a personal area network (e.g., Bluetooth), near field communication (NFC), and / or any additional types of radio frequency communication. However, additional or alternative communication methods such as Dedicated Short Range Communication (DSRC) channels and / or mobile telecommunications protocols based on 3GPP standards are also considered within the scope of this disclosure. A DSRC channel refers to a unidirectional or bidirectional short- to medium-range wireless communication channel designed specifically for automotive use, along with a set of corresponding protocols and standards. 3GPP refers to a partnership among multiple standards organizations that develop mobile telecommunications protocols and standards. 3GPP standards are structured as "releases." Therefore, communication methods based on 3GPP releases 14, 15, 16, and / or future 3GPP releases are considered within the scope of this disclosure.

[0054] Therefore, the test vehicle communication system 54 may include one or more antennas and / or communication transceivers for receiving and / or transmitting signals, such as Cooperative Sensing Messages (CSM). The test vehicle communication system 54 is configured to wirelessly transmit information between the test vehicle 12b and another vehicle. Furthermore, the test vehicle communication system 54 is configured to wirelessly transmit information between the test vehicle 12b and infrastructure or other vehicles. It should be understood that the test vehicle communication system 54 may be integrated with the test vehicle controller 52 (e.g., integrated on the same circuit board as the test vehicle controller 52, or otherwise incorporated into the test vehicle controller 52) without departing from the scope of the invention.

[0055] In one exemplary embodiment, the test vehicle controller 52 is configured to receive signals transmitted by one or more transmit antenna arrays 34 using the test vehicle communication system 54. In a non-limiting example, the test vehicle controller 52 evaluates signal characteristics, such as signal strength, signal-to-noise ratio, etc. The test vehicle controller 52 also evaluates connectivity characteristics, such as transmission speed / bandwidth, latency, etc. In one exemplary embodiment, the test vehicle controller 52 communicates electrically with the test controller 30 to transmit signal characteristics, connectivity characteristics, and / or additional signal measurement data to the test controller 30 for further analysis.

[0056] It should be understood that the test vehicle 12b and the test vehicle system 50 are merely exemplary in nature, and the system 10b can be used to test any device capable of wireless communication, including, for example, mobile devices (e.g., smartphones), aircraft, watercraft, spacecraft, etc.

[0057] Reference Figure 3 A flowchart of a method 100 for determining cellular signal characteristics is shown. Measurement system 10a and test system 10b are collectively referred to as the system for determining cellular signal characteristics. The system for determining cellular signal characteristics is used to perform the method 100 for determining cellular signal characteristics. Method 100 begins at block 102 and proceeds to blocks 104 and 106. At block 104, measurement controller 14 uses measurement antenna array 16 to continuously receive multiple cellular signal data as measurement vehicle 12a passes through (i.e., moves across) environment 24. Within the scope of this disclosure, the multiple cellular signal data includes all cellular signals received by measurement antenna array 16 in environment 24. In a non-limiting example, measurement controller 14 records the multiple cellular signal data along with a timestamp of the reception of each of the multiple cellular signal data in medium 22 of measurement controller 14. It should be understood that system 10 and method 100 of this disclosure can be used to determine the signal characteristics of other RF signals, including, for example, wireless local area network (WLAN) signals, personal area network (e.g., Bluetooth) signals, near field communication (NFC) signals, etc. The signal characteristics of other RF signals can be collectively referred to as RF signal characteristics. After box 104, method 100 proceeds to box 108, which will be discussed in more detail below.

[0058] At block 106, measurement controller 14 continuously determines multiple vehicle positions using GNSS 18 as measurement vehicle 12a passes through environment 24. In a non-limiting example, measurement controller 14 records the multiple vehicle positions along with a timestamp of each of the multiple vehicle positions in medium 22 of measurement controller 14. Following block 106, method 100 proceeds to block 108.

[0059] At block 108, the measurement controller 14 aligns a subset of multiple cellular signal data with each of a plurality of locations in environment 24. In an exemplary embodiment, the measurement controller 14 spatially aligns the multiple cellular signal data using a reception timestamp for each of the multiple cellular signal data and a location timestamp for each of the multiple vehicle locations. For example, the result of block 108 is that at each of the multiple locations in environment 24 (e.g., locations spaced fifty meters apart along a particular road), all cellular signals received by the measurement antenna array 16 in environment 24 are known. In a non-limiting example, the alignment data is stored in medium 22 of the measurement controller 14 in the form of a database. Following block 108, method 100 proceeds to block 110.

[0060] At block 110, the cellular signal data aligned to the location determined at block 108 is transmitted to test controller 30. In one exemplary embodiment, the location-aligned cellular signal data is transmitted using the Internet and wireless and / or wired communications. In another exemplary embodiment, the location-aligned cellular signal data is transmitted directly from measurement controller 14 to test controller 30 using wireless and / or wired point-to-point communications. It should be understood that the location-aligned cellular signal data may first be transmitted to an intermediate system (e.g., a desktop computer, server system, etc.) for additional backup, storage, and / or post-processing before being sent to test controller 30, without departing from the scope of this disclosure. After block 110, method 100 proceeds to block 112.

[0061] At block 112, test controller 30 determines the noise floor for each of the plurality of locations in environment 24 based at least in part on cellular signal data aligned at the plurality of locations received at block 110. Within the scope of this disclosure, noise floor is a measurement of received signals other than cellular signals (e.g., thermal noise, atmospheric noise, other non-cellular RF signals, etc.). In an exemplary embodiment, test controller 30 determines the noise floor by identifying the minimum received signal amplitude at each of the plurality of locations in environment 24. Following block 112, method 100 proceeds to block 114.

[0062] At block 114, test controller 30 identifies one or more regions of interest at each of a plurality of locations in environment 24. Within the scope of this disclosure, a region of interest is the starting region in environment 24 where a cellular signal approaches the measuring vehicle 12a. In a non-limiting example, a region of interest at any given location in the plurality of locations is defined as a region in environment 24 where the received RF energy is higher than the noise floor at the given locations in the plurality of locations identified at block 112. In an exemplary embodiment, to identify one or more regions of interest at each of the plurality of locations, test controller 30 uses receive beamforming.

[0063] In one exemplary embodiment, receive beamforming means that the test controller 30 applies a set of weighting coefficients to the signals received by each antenna element in the measurement antenna array 16 to generate a first virtual receive beam. Cellular signals with azimuth and zenith angles falling within the first virtual receive beam are detected by the first virtual receive beam. By adjusting the set of weighting coefficients, the test controller 30 moves the first virtual receive beam (i.e., adjusts the azimuth and zenith angles of the center of the first virtual receive beam relative to the measurement vehicle 12a) to scan multiple cellular signal data in space. In a non-limiting example, the first virtual receive beam has a first beamwidth (e.g., three meters).

[0064] In a non-limiting example, the test controller 30 uses receive beamforming with a first virtual receive beam to scan in all directions around the measurement vehicle 12a at each of the multiple locations and identify one or more regions of interest at each of the multiple locations (e.g., defined as one or more azimuth and zenith angle ranges). After block 114, method 100 proceeds to block 116.

[0065] At block 116, test controller 30 is positioned at each of one or more individual cellular signals at each of a plurality of locations in environment 24. Within the scope of this disclosure, an individual cellular signal is a different RF transmission originating from a particular cellular device (e.g., a smartphone) or a particular cellular base station (i.e., a cell tower). For example, an individual cellular signal may include a broadcast control channel signal, a synchronization signal, a reference signal, etc. In one exemplary embodiment, test controller 30 uses receive beamforming to position each of one or more individual cellular signals.

[0066] In one exemplary embodiment, the test controller 30 applies a set of weighting coefficients to the signals received by each antenna element in the measurement antenna array 16 to generate a second virtual receive beam. Cellular signals with azimuth and zenith angles falling within the second virtual receive beam are detected using this second virtual receive beam. By adjusting the set of weighting coefficients, the test controller 30 moves the second virtual receive beam (i.e., adjusts the azimuth and zenith angles of the center of the second virtual receive beam relative to the measurement vehicle 12a) to spatially scan multiple cellular signal data. In a non-limiting example, the second virtual receive beam has a second beamwidth (e.g., ten centimeters) that is smaller than the width of the first beam.

[0067] In a non-limiting example, test controller 30 uses receive beamforming with a second virtual receive beam to scan within each of one or more regions of interest at each of the plurality of locations defined at block 114. In an exemplary embodiment, test controller 30 decodes the received data to identify one or more individual cellular signals. For example, test controller 30 may distinguish one or more individual cellular signals based on network identification information (e.g., cell ID) contained in each of the one or more individual cellular signals. In another example, test controller 30 may distinguish one or more individual cellular signals based on additional signal characteristics including, for example, frequency band, channel number, etc.

[0068] In one exemplary embodiment, the test controller 30 records the data transmitted by each of one or more individual cellular signals, as well as the azimuth and zenith angles of arrival of each of the one or more individual cellular signals, in a medium 38 of the test controller 30. After block 116, method 100 proceeds to blocks 118 and 120.

[0069] At block 118, test controller 30 determines one or more physical cellular signal characteristics for each of one or more individual cellular signals at each of a plurality of locations. In an exemplary embodiment, the one or more physical cellular signal characteristics include at least one of the following: the direction of arrival of each of the one or more individual cellular signals (i.e., the azimuth and zenith angles of arrival of each of the one or more individual cellular signals), the amplitude of each of the one or more individual cellular signals, the phase of each of the one or more individual cellular signals, the signal strength of each of the one or more individual cellular signals, the signal-to-noise ratio of each of the one or more individual cellular signals, and / or the time of arrival of each of the one or more individual cellular signals. In a non-limiting example, test controller 30 determines one or more physical cellular signal characteristics for each of the one or more individual cellular signals by performing signal processing on each of the one or more individual cellular signals. Following block 118, method 100 proceeds to block 122, as will be discussed in more detail below.

[0070] At block 120, test controller 30 determines identification metadata for each of one or more individual cellular signals at each of a plurality of locations. In one exemplary embodiment, the identification metadata provides at least information about the base station initiating each of the one or more individual cellular signals. In another exemplary embodiment, the identification metadata further includes at least one of the following: cell identifier (cell ID), system information block (SIB), master information block (MIB), and / or service set identifier (SSID). In a non-limiting example, test controller 30 determines the identification metadata for each of the one or more individual cellular signals by decoding each of the one or more individual cellular signals and extracting identification information from each of the one or more individual cellular signals. Following block 120, method 100 proceeds to block 122.

[0071] At block 122, test controller 30 determines additional relevant information about each of one or more individual cellular signals at each of a plurality of locations. In an exemplary embodiment, test controller 30 identifies which of the one or more individual cellular signals (if any) is a multipath signal (i.e., a signal that has been reflected) and which of the one or more individual cellular signals (if any) is a direct signal (i.e., a signal received directly from a base station without reflection). In a non-limiting example, test controller 30 identifies multipath signals and direct signals at least in part based on one or more physical cellular signal characteristics of each of the one or more individual cellular signals determined at block 118, and / or identifies identification metadata about each of the one or more individual cellular signals determined at block 120. In a non-limiting example, to identify multipath signals and direct signals, test controller 30 identifies signals originating from the same base station based on identification metadata and distinguishes direct signals and multipath signals based on one or more physical cellular signal characteristics (e.g., time of arrival). After block 122, method 100 proceeds to block 124.

[0072] At block 124, test controller 30 uses one or more transmit antenna arrays 34 to reproduce each of one or more individual cellular signals at each of a plurality of locations within an anechoic chamber 32 having test vehicle 12b. In one exemplary embodiment, test controller 30 uses one or more transmit antenna arrays 34 to generate a signal having at least the same physical cellular signal characteristics as each of the one or more individual cellular signals determined at block 118. In another exemplary embodiment, test controller 30 uses one or more transmit antenna arrays 34 to generate a signal having at least the same identification metadata as each of the one or more individual cellular signals determined at block 120.

[0073] In one exemplary embodiment, the test controller 30 sequentially reproduces each of one or more individual cellular signals at each of a plurality of locations to simulate driving the test vehicle 12b through environment 24 and through each of the plurality of locations. After block 124, method 100 proceeds to block 126.

[0074] At block 126, the test vehicle controller 52 uses the test vehicle communication system 54 to receive signals transmitted at block 124 by one or more transmit antenna arrays 34. In an exemplary embodiment, the test vehicle controller 52 records signal quality information, such as received signal strength, signal-to-noise ratio, etc. In a non-limiting example, the test vehicle controller 52 transmits the signal quality information to the test controller 30 for data processing and aggregation. In an exemplary embodiment, the data collected by performing blocks 124 and 126 is used to optimize the design, orientation, size, and / or placement of the test vehicle communication system 54 of the test vehicle 12b to maximize the performance of the test vehicle communication system 54. After block 126, method 100 continues to enter a standby state at block 128.

[0075] In one exemplary embodiment, method 100 repeatedly exits standby state 128 and restarts at block 102. In a non-limiting example, method 100 exits standby state 128 and restarts according to a timer, for example, every three hundred milliseconds.

[0076] The systems 10a, 10b, and method 100 of this disclosure offer several advantages. Using measurement system 10a, real-world cellular signal data can be collected for a wide variety of environments (e.g., urban, suburban, rural, remote), under various environmental conditions (e.g., weather conditions), and in various locations around the world. Continuous reception of all signals in environment 24 using measurement antenna array 16 allows measurement vehicle 12a to pass through the environment at normal speeds without obstructing traffic flow. Performing receive beamforming in post-processing using test system 10b allows analysis of the data collected by measurement system 10a and isolation and characterization of individual cellular signals without requiring real-time processing capabilities on measurement vehicle 12a. The use of test system 10b with anechoic chamber 32 allows simulation of different RF environments, enabling rapid testing of test vehicle 12b or other test equipment (DUT) under a wide range of operating conditions that reflect the real-world conditions of the measurement.

[0077] The descriptions in this disclosure are merely exemplary in nature, and variations thereof that do not depart from the spirit and scope of this disclosure are intended to fall within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A method for determining cellular signal characteristics, comprising: Receive and record multiple cellular signal data at one of multiple locations in an environment, wherein the multiple cellular signal data includes cellular signals received at one of the multiple locations in the environment; The identification of one or more individual cellular signals received at one of the plurality of locations is based at least in part on the plurality of cellular signal data; Based at least in part on the plurality of cellular signal data, determine one or more cellular signal characteristics of each of the one or more individual cellular signals received at one of the plurality of locations; and The one or more individual cellular signals at one of the multiple locations in the environment are simulated, at least in part, based on the characteristics of each of the one or more individual cellular signals received at one of the multiple locations.

2. The method according to claim 1, wherein, Receiving and recording the plurality of cellular signal data also includes: The survey vehicle is used to traverse the multiple locations, wherein the survey vehicle is equipped with a survey antenna array and a Global Navigation Satellite System (GNSS); The measurement antenna array is used to continuously receive and record the multiple cellular signal data; The GNSS was used to continuously determine and record the positions of multiple vehicles; and At least in part, a subset of the plurality of cellular signal data is aligned with each of the plurality of locations based on the plurality of vehicle locations.

3. The method according to claim 1, wherein, Identifying the one or more individual cellular signals also includes: The ambient noise level is determined at least in part based on the plurality of cellular signal data; Based at least in part on the plurality of cellular signal data, receive beamforming is used to identify one or more regions of interest in the environment that have energy higher than the noise floor; and Receive beamforming is used to locate each of the one or more individual cellular signals within the one or more regions of interest.

4. The method according to claim 3, wherein, Identifying the one or more regions of interest also includes: The plurality of cellular signal data are scanned in space using a first beam with a first beamwidth to identify the one or more regions of interest.

5. The method according to claim 4, wherein, Locating each of the one or more individual cellular signals further includes: The one or more regions of interest are scanned in space using a second beam with a second beamwidth to locate the one or more individual cellular signals, wherein the second beamwidth is smaller than the first beamwidth.

6. The method according to claim 1, wherein, Determining the one or more cellular signal characteristics of each of the one or more individual cellular signals further includes: Determine the direction of arrival for each of the one or more individual cellular signals; Determine the amplitude of each of the one or more individual cellular signals; Determine the phase of each of the one or more individual cellular signals; and Determine the arrival time of each of the one or more individual cellular signals.

7. The method according to claim 6, wherein, Determining the one or more cellular signal characteristics of each of the one or more individual cellular signals further includes: Determine identification metadata for each of the one or more individual cellular signals, wherein the identification metadata provides at least information about the base station that initiated each of the one or more individual cellular signals.

8. The method according to claim 7, wherein, Determining the identification metadata also includes: Determine the identification metadata for each of the one or more individual cellular signals, wherein the identification metadata includes at least one of the following: cell ID, system information block (SIB), master information block (MIB), and service set identifier (SSID).

9. The method according to claim 7, further comprising: The identification of which of the one or more individual cellular signals is a multipath signal is based at least in part on the characteristics of each of the one or more individual cellular signals.

10. The method according to claim 1, wherein, Simulating the one or more individual cellular signals also includes: Each of the one or more individual cellular signals is reproduced in an anechoic chamber containing the test vehicle.

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