WO2020038833A1

WO2020038833A1 - System and method for monitoring antenna performance

Info

Publication number: WO2020038833A1
Application number: PCT/EP2019/071979
Authority: WO
Inventors: Fabio Deperini; Carlo Antonini
Original assignee: Telit Communications S.P.A.
Priority date: 2018-08-21
Filing date: 2019-08-15
Publication date: 2020-02-27

Abstract

A system and method for detecting the presence and performance status of an antenna within a wireless telecommunications device, comprising monitoring a radio frequency (RF) power flow inside the wireless device using a directional coupler to measure both forward RF power originating from the device towards the antenna and reflected RF power originating from the antenna or other discontinuity and reflected back into the device, measuring a return loss based on a discrepancy between the forward RF power and the reflected RF power, comparing the return loss with one or more predetermined threshold values, and determining if the antenna is performing optimally or sub- optimally based on the comparison.

Description

SYSTEM AND METHOD FOR MONITORING ANTENNA PERFORMANCE

CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claims the benefit of U.S. Provisional Application Serial No. 62/720,779, filed August 21, 2018, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[002] Embodiments of the invention relate to the field of wireless communication transceivers, and in particular, to the detection of the presence and performance of the antenna system in a wireless device. Some embodiments relate to the use of wireless communication transceivers to connect a network of devices in an Internet of Things (“IoT”) system and for monitoring their performance.

BACKGROUND OF THE INVENTION

[003] The“Internet of Things” (IoT) is an inter-connected network of communication devices (e.g.“smart” devices) with electronics, sensors, software and network connectivity.

IoT communication devices may be deployed to monitor technical devices, such as automobiles, security systems, medical devices including biological implants, home appliances etc. IoT devices may measure and/or gather data about the environment in which they are deployed. An IoT communication device may have a telecommunication transceiver or modem which allows the IoT communication device to transmit and/or receive data to/from a monitoring device over a wireless network, such as the Internet. IoT devices are often wireless and require an adequate antenna system to function properly.

[004] A deployed antenna may be integrated inside the device (embedded antenna) or plugged/screwed outside (external antenna). In either case, the antenna may be detached, missing or broken, or may break during operation in the field. There is therefore a need to monitor the function of the antenna itself.

[005] The conventional method for detecting antenna function consists of sensing a DC resistance across the antenna terminals, while decoupling it from the radiofrequency signal. Antennas predisposed for this testing are often mounted to e.g., a 10 kilo-ohm ^W) resistor between a shield and a core of a feeding coaxial cable. If the antenna’s DC resistance is approximately 10kW, then it is present with a good connection. However, if the antenna’s DC resistance is significantly lower than 101<W, then the antenna is shorted and if the antenna’ s DC resistance is significantly higher than 101<W, then the antenna is disconnected. The resistance values for normal, shorted and disconnected states may differ for various transceivers.

[006] However, this method for detecting antenna function has two major flaws. Firstly, it is not suited for antennas that have 0W DC resistance by design (e.g. inverted F-antenna (IFA) or planar IFA (PIFA) antennas), because it cannot distinguish normal 0 Ohm operation from a short circuit. Secondly, this method can only detect when the antenna is entirely disconnected or broken, in which case the wireless device cannot communicate that failure because it would need the antenna to communicate, which has already broken.

[007] Accordingly, there is the need for a more sophisticated antenna presence detection that can distinguish between a 0W DC resistance antenna and a short circuit, and furthermore that can detect a degradation in antenna performance or partial damage so that the device can send a distress signal to repair the antenna while it is still able to communicate (before the antenna completely fails).

SUMMARY OF THE INVENTION

[008] According to some embodiments of the present invention, a method, device and system are provided for detecting the presence of an antenna and its performance status, within a telecommunications device. The RF power flow is monitored inside the wireless device, generally by a directional coupler, that measures the reflected and/or the forward RF power. Ideally, when the antenna performs optimally, the reflected RF power is substantially less than the forward RF power (e.g. 1/3 of the forward power or less). However, when the antenna’s performance degrades, the antenna no longer has a load that is perfectly matched to the 50W of the RF Power Amplifier, and the power to the antenna will reflect back towards the coupler. Thus, the reflected RF power grows (e.g. equal or higher than the forward power) with respect to the forward RF power, the worse the antenna performance.

[009] The processor may determine the return loss (or a parameter derived therefrom) based on a measurement carried out by the RF coupler, which quantifies the amount of power lost or reflected by the antenna in relation to the power incident to it, and thus the degree of to which the antenna has degraded. In one embodiment, the return loss may measure the ratio or other relationship between the reflected power and the incident power, in some other embodiment the ratio between the forward power and the reflected power can be measured; the two ratios are linked by a well-known relationship. A relatively higher discrepancy is associated with a lower reflected power and thus, relatively better antenna performance, whereas a relatively lower discrepancy is associated with a relatively higher reflected power and thus, relatively worse or failing antenna performance. The return loss (or a parameter derived therefrom) may be recorded as a value in a continuous range, and/or as one or more discrete states (e.g., antenna present vs. antenna disconnected, or good, acceptable, or poor performance). The antenna state may be determined by comparing the return loss (or value derived therefrom) to a first threshold to determine if the antenna is present (e.g., if the function is greater than or equal to the first threshold) and/or a second (or more) threshold(s) to determine if the antenna has optimal performance (e.g., if the function is greater than or equal to the second threshold(s)).

[010] Other measures of return loss may be any computed based on the reflected power alone, or in combination with the forward power. Examples of return loss include a difference between the forward power and the reflected power expressed in dBm (e.g., forward power (dBm) - reflected power (dBm), as discussed above), a ratio between the forward and reflected power (e.g., reflected power/forward power), any function of reflected power alone (e.g., absolute value, rate of change, etc.), a difference between the reflected power and another benchmark (e.g., average forward power, network requested forward power, etc.), or any parameter derived therefrom (e.g., a reflection coefficient).

[011] In some embodiments of the invention, the return loss (or a parameter derived therefrom, such as, a reflection coefficient) may be logged internally in the device memory and/or sent to a Cloud server to be logged remotely. Variations in the return loss (or derived parameter) over time, as the antenna ages, may then be used, e.g., by the Cloud service, to monitor the health or performance of the antenna and issue an alert when a permanent or significant decrease in antenna performance is detected.

[012] In some embodiments of the invention, antenna optimization is provided in a system with two or more antennas, one of which is designated as a primary antenna (e.g., queued with higher priority or more data) and another of which is designated as a secondary antenna (e.g., queued with lower priority or less data). Based on the antennae performance measures of the various antennae, the system may switch designations on-the-fly of which antenna is primary and secondary based on real-time performance measurements, so that at any given time, the relatively best performing antenna is the primary antenna. Such embodiments improve antenna efficiency by using the best performing antenna to transmit, e.g., higher priority data and/or more of the data.

[013] In some embodiments of the invention, a failsafe antenna system is provided, in which the system has a primary antenna and one or more backup antennae. When failure is detected in the primary antenna, operation is automatically switched to a backup antenna, to ensure the system can communicate, even after the primary antenna fails. Such embodiments improve network efficiency by preventing communication failure and/or loss of data.

BRIEF DESCRIPTION OF THE DRAWINGS

[014] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[015] Figure 1 is a schematic illustration of a system for monitoring antenna performance according to some embodiments of the invention; and

[016] Figure 2 is a flow chart depicting a method of monitoring antenna performance according to some embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[017] Some embodiments of the invention may solve the problem that conventional detectors can only detect a complete failure of an antenna, at which point it is too late because the broken antenna cannot communicate such failure to the system. According to some embodiments, there is a method, device and system for detecting degraded antenna performance prior to failure (e.g., when the antenna is still working, but with diminished output power). Such embodiments, allow the device to use the damaged antenna to send a warning or alert to the system (e.g., to request repair), or to automatically switch antennas to a best-performing antenna in a multi-antenna system to optimize performance and/or avoid communication failure.

[018] Some embodiments of the invention may compute antenna performance based on a return loss, which may be a measure of the reflected and/or forward power.“Forward” RF power may refer to power flowing in a direction originating at the RF Power Amplifier, travelling past the directional coupler, and towards the antenna. In the event of a damaged or missing antenna (or other circuit component), a discontinuity in the forward flow of power may arise in the system. This discontinuity may cause some (or all) of the forward power, which cannot radiate outward due to the antenna damage, to reflect back from the antenna inward into the device and past across the coupler. Thus, the reflected RF signal may originate from the damaged component (antenna, cable, connection etc.), carried over the coupler and back into the device. Conversely, in the event of a healthy and perfectly functioning antenna, no (or a negligible) discontinuity may arise, resulting in little to no reflected power as measured by the return loss.

[019] Whereas conventional methods detect a binary antenna state (e.g., working or not working), the return loss, measured according to embodiments of the invention, may record antenna performance on a continuous scale (e.g., any value in a range of from infinite dB to OdB) or, by applying thresholds thereto, in multiple states (e.g., optimal, acceptable, degraded, and non-functioning). Thus, embodiments of the invention may identify degrading antenna performance prior to failure and at an earlier stage than conventional methods.

[020] An RF coupler may be used to measure forward and reflected power to derive the return loss (or another derived parameter, e.g., a reflection coefficient). RF couplers come standard in 4G (LTE) modems as an embedded device. An example RF coupler (e.g., a four port/pin device) has at least one port for recording the reflected power and at least one port for recording the emitted power. Whereas a conventional DC resistor cannot determine reflected power, and, in LTE, there is no interest in reflected power, according to embodiments of the invention, both the forward and reflected powers are recorded to measure the discrepancy or power/return loss therebetween.

[021] According to some embodiments of the invention, the“return loss” may measure the ratio of reflected power vs the forward power. A relatively high or above threshold “retum loss”, associated with a minimal reflected power, indicates that the antenna has good performance, whereas a relatively low return loss, associated with a maximal reflected power, indicates that the antenna is damaged or failing. For example, if the antenna bends in storm, there should be a change in this return loss. Other measures of return loss include, for example, a ratio of the reflected power against the incident power (sum of reflected and forward power), a function of the reflected power alone (e.g. absolute value, rate of change, etc.), the difference between reflected power and another benchmark (e.g., average forward power, network requested forward power, ideal average forward power pre-stored in the device memory, etc.).

[022] Some embodiments may minimize false alarms, where an antenna’ s performance is only temporarily degraded, but later returns to its improved or prior state. This may occur, e.g., when an antenna is temporarily bent, but later unbends. Some embodiments may detect false alarms by setting a timer for a lockout period. If the antenna’s performance is still degraded after the lockout period, the local device or system may verify the degraded performance; whereas if the antenna’s performance returns to its prior state during the lockout period, the local device or system may indicate a false alarm or may avoid sending an alert or taking other action in the first place.

[023] As used herein“antenna” may refer to a physical conducting interface between radio waves propagating through space and electric currents moving in metal conductors therein. An antenna is typically used with a transmitter or receiver. Terms such as “forward” and “reflected” as used herein may refer to a direction of travel of electromagnetic flow (forward referring to a signal originating at the local device, carried along a circuit past the directional coupler, and toward the antenna and reflected referring to a signal originating from a discontinuity at the antenna or other damaged transceiver component, carried over the coupler and back into the device).

[024] Some embodiments of the invention may provide a system for detecting the presence and/or performance of an antenna. The antenna may be part of a telecommunications device, for example a mobile phone. The antenna is designed to transmit and receive radio waves and may function either in all horizontal directions equally (omnidirectional antennas), or in a particular direction (directional or high gain antennas). The telecommunications device may be an IoT telecommunications device, able to connect to a network of inter-connected devices. A system according to some embodiments of the invention is described with reference to Figure 1.

[025] Figure 1 schematically illustrates an antenna performance detection system according to some embodiments of the invention. An IoT device 80 contains a telecommunications device 100, including or operably connected to one or more antenna(e) 1. The telecommunications device 100 includes an RF coupler 115, RF power meter 120, processor 125, memory 130 and an Operating System (OS) 135. The OS 135 may be executed by the processor 125. The antenna 1 of the IoT device 80 is able to communicate with the network infrastructure 40 via a communication link 35. This communication link 35 may be across radio frequencies or any other suitable wavelengths on the electromagnetic spectrum.

[026] To facilitate the ability of the IoT device 80 to form part of an IoT network, the device 80 is connected to a network such as the Internet 60, e.g., via an Internet IP connection 65. Furthermore, the network infrastructure 40 connects to the Internet via communication link 35. The network infrastructure 40 may be an E-nodeB of an LTE network according to some embodiments of the invention.

[027] The system may also include a cloud server 50 and/or a remote monitoring and control device 20 for remotely monitoring antenna 1 performance. The device 20 may include a display 112 and a processor 96. This device 20 may also be known as a user device. The device connects to the network infrastructure via communication link 35 and to the Internet via Internet IP connection 65. Information regarding the IoT device 80 can be transmitted to the user device 20 via the Internet 60. The cloud server 50 connects to the Internet 60 via Internet IP connection 65.

[028] According to some embodiments of the invention, the RF power flow may be monitored inside the wireless IoT device 80 via the RF coupler 115. Both the forward power (P_f) to the antenna 1 and the reflected power (P_r) back from the antenna 1 may be measured by the RF coupler 115. Processor 125 then measures the discrepancy between the emitted power and the reflected power to determine a return loss of reflected power and forward power across the antenna 1. [029] According to some embodiments of the invention, the antenna performance, namely said return loss or a parameter derived therefrom is reported to devices 20 and/or 50 to decide how to proceed; if required, a notification requesting repair will be sent.

[030] According to some embodiments of the invention, multiple antennas can be used as a failsafe mechanism. The system may comprise a primary antenna and one or more backup antennae. The system may switch to said backup antenna(e) to improve performance in the event of weakening primary antenna or to prevent total failure of system communication in the event one antenna is entirely damaged.

[031] Figure 2 is a flow chart of a method for detecting antenna presence and performance according to some embodiments of the invention. The operations of Figure 2 may be implemented in a processor 125 contained within the device 80 of Figure 1, or any other device containing one or more antennae.

[032] In operation 205, forward power P_f and reflected power P_r of an antenna may be measured.

[033] In operation 210, the return loss (RL) or a parameter derived therefrom may be evaluated from the two measures at operation 205.

[034] In operation 215, the return loss or derived parameter may be compared against one or more predetermined thresholds (TH). If the return loss or derived parameter is greater than the highest threshold, the method may proceed to operation 220; otherwise, the method may proceed to operation 225.

[035] In operation 220, the antenna may be declared to be present and functioning in an optimal manner when the return loss or a parameter derived therefrom is greater than the threshold value at operation 215.

[036] In operation 225, the antenna may be declared to be not present if the return loss is less than the lowest threshold or not functioning in an optimal manner if the return loss is less than one or more other intermediate threshold values.

[037] The antenna may stop functioning properly due to damage from internal or environmental factors, which may cause a break or a bend in the structure of the antenna. If the antenna is damaged in such a manner during operation, then according to some embodiments of the invention, there may be a significant drop in the return loss. In an extreme situation, the antenna may not be present at all due to extensive damage resulting in the complete destruction of the antenna.

[038] Over time, there may be a slower degradation of antenna performance. It is advantageous to know the performance status of an antenna before a complete and irreversible break occurs. According to some embodiments of the invention, antenna performance may be tested over a longer period of time to determine durability of the antenna.

[039] According to some embodiments of the invention, if decreased performance, indicative of failing performance of the antenna, is measured, the network may send an alert to the user device 20 or cloud server 50 to repair the antenna.

[040] According to some embodiments of the invention, said alert sent by the network 40 may consist of an automatic request to boost performance. This performance boost may consist of switching to a backup antenna that the IoT device may possess in order to continue communicating with optimal performance.

[041] According to some embodiments of the invention, the return loss may be internally logged in the device. This logging may utilise the internal memory 130. Alternatively, according to some embodiments of the invention, a measure of the return loss may be sent to, and logged by, the cloud server 50.

[042] According to some embodiments of the invention, a performance check on the antenna may be defined as comprising variations of the logged antenna return loss over time. When a permanent decrease in the performance of the antenna is detected, a warning message may be sent from the network to the user device 20 or cloud server 50.

[043] In the foregoing description, various aspects of the present invention are described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the present invention. However, it will also be apparent to persons of ordinary skill in the art that the present invention may be practiced without the specific details presented herein. Furthermore, well known features may be omitted or simplified in order not to obscure the present invention. [044] Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as "processing," "computing," "calculating," "determining," or the like, refer to the action and/or processes of a computer or computing system, or similar electronic computing device, that manipulates and/or transforms data represented as physical, such as electronic, quantities within the computing system's registers and/or memories into other data similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices.

[045] The aforementioned flowchart and block diagrams illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which may comprise one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures or by different modules. Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed at the same point in time. Each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[046] Embodiments of the invention may include an article such as a non-transitory computer or processor readable medium, or a computer or processor non-transitory storage medium, such as for example a memory, a disk drive, or a USB flash memory, encoding, including or storing instructions, e.g., computer-executable instructions, which, when executed by a processor or controller, carry out methods disclosed herein.

[047] In the above description, an embodiment is an example or implementation of the inventions. The various appearances of “one embodiment,” “an embodiment” or“some embodiments” do not necessarily all refer to the same embodiments. Although various features of the invention may be described in the context of a single embodiment, the features of embodiments may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment. Reference in the specification to “some embodiments”, “an embodiment”, “one embodiment” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the inventions. It will further be recognized that the aspects of the invention described hereinabove may be combined or otherwise coexist in embodiments of the invention.

[048] The descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only. While certain features of the present invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall with the true spirit of the invention.

[049] While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention. Different embodiments are disclosed herein. Features of certain embodiments may be combined with features of other embodiments; thus, certain embodiments may be combinations of features of multiple embodiments.

Claims

1. A method of detecting the presence and performance status of an antenna within a wireless telecommunications device, the method comprising:

monitoring a radio frequency (RF) power flow inside the wireless device using a directional coupler to measure both forward RF power originating from the device towards the antenna and reflected RF power from the antenna or other discontinuity and reflected back into the device;

measuring a return loss based on a discrepancy between the forward RF power and the reflected RF power;

comparing the return loss with one or more predetermined threshold values; and determining if the antenna is performing optimally or sub-optimally based on the comparison.

2. The method of claim 1 comprising issuing an alert over a wireless network in response to detecting a permanent decrease in the return loss of the antenna below the one or more predetermined threshold values.

3. The method of claim 1 comprising automatically switching from communicating with the antenna to communicating with another backup antenna in the device in response to detecting that the return loss is below the one or more predetermined threshold values.

4. The method of claim 1 comprising automatically switching the antenna from a primary role to a secondary antenna role when a second antenna is determined to have a greater return loss than the antenna.

5. The method of claim 1 comprising detecting a false alarm when the return loss of the antenna is below the one or more predetermined threshold values for less than a predetermined period of time, after which the return loss of the antenna reverts to being above the one or more predetermined threshold values.

6. The method of claim 1 comprising internally logging the return loss in a memory in the device.

7. The method of claim 1 comprising sending the return loss to a remote server to be remotely logged.

8. The method of claim 1 comprising defining a performance check on the antenna using variations over time of the logged antenna return loss.

9. The method of any of claims 1 to 8 wherein a parameter derived from the return loss is used instead of the return loss.

10. The method of claim 9 wherein the derived parameter is a reflection coefficient.

11. A telecommunications device comprising:

one or more processors configured to:

monitor a radio frequency (RF) power flow inside the wireless device using a directional coupler to measure both forward RF power originating from the device towards an antenna and reflected RF power from the antenna or other discontinuity and reflected back into the device,

measure a return loss based on a discrepancy between the forward RF power and the reflected RF power,

compare the return loss with one or more predetermined threshold values, and determine if the antenna is performing optimally or sub-optimally based on the comparison.

12. The telecommunications device of claim 11 comprising the antenna and the directional coupler.

13. The telecommunications device of claim 11, wherein the one or more processors are further configured to issue an alert over a wireless network in response to detecting a permanent decrease in the return loss of the antenna below the one or more predetermined threshold values.

14. The telecommunications device of claim 11, wherein the one or more processors are further configured to automatically switch from communicating with the antenna to communicating with another backup antenna in the device in response to detecting that the return loss is below the one or more predetermined threshold values.

15. The telecommunications device of claim 11, wherein the one or more processors are further configured to automatically switch the antenna from a primary role to a secondary antenna role when a second antenna is determined to have a greater return loss than the antenna.

16. The telecommunications device of claim 11, wherein the one or more processors are further configured to detect a false alarm when the return loss of the antenna is below the one or more predetermined threshold values for less than a predetermined period of time, after which the return loss of the antenna reverts to being above the one or more predetermined threshold values.

17. The telecommunications device of claim 11, wherein the one or more processors are further configured to internally log the return loss in a memory in the device.

18. The telecommunications device of claim 11, wherein the one or more processors are further configured to send the return loss to a remote server to be remotely logged.

19. The telecommunications device of claim 11, wherein the one or more processors are further configured to define a performance check on the antenna using variations over time of the logged antenna return loss.

20. The telecommunications device of claim 11, wherein a parameter derived from the return loss is used instead of the return loss.

21. The telecommunications device of claim 11, wherein the derived parameter is a reflection coefficient.

22. A system comprising:

a remote server in communication with a telecommunications device comprising the antenna and the directional coupler, the remote server comprising one or more processors configured to:

detect the presence and performance status of the antenna within the telecommunications device, by comparing a return loss or parameter derived therefrom, evaluated from measurements of the forward and reflected RF power, with one or more predetermined threshold values and logging the results on a cloud server.

23. A non-transitory computer readable medium comprising instructions which, when implemented on one or more processors in a computing system, cause the processors to:

measure both forward RF power originating from a wireless telecommunications device towards an antenna and reflected RF power originating from the antenna or other discontinuity and reflected back into the device;

measure a return loss based on a discrepancy between the forward RF power and the reflected RF power;

compare the return loss with one or more predetermined threshold values; and determine if the antenna is performing optimally or sub-optimally based on the comparison.