Wireless communication system and method

Abstract

A method is disclosed that is performed in a wireless communication system. The method includes generating a first local signal; receiving, at a receiver, a first signal from a remote source; determining a movement of the receiver; generating a first correlation signal by correlating the first local signal with the received first signal; providing motion compensation for at least one of the first local signal, the received first signal, and the first correlation signal based on the determined movement of the receiver along a direction of interest, thereby generating a first motion-compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal is received along the direction of interest; after determining that the first signal is received along the direction of interest, generating a second local signal, wherein the second local signal has at least one parameter based on the first signal received along the direction of interest; receiving, at the receiver, a second signal along the direction of interest; and processing the received second signal using the second local signal to determine a figure of merit related to the receiver and / or related to a communication link including the receiver. A wireless communication system is also disclosed.

Description

Technical Field

[0001] The present invention relates to a wireless communication system and method. The present invention is particularly applicable to a positioning system such as a GNSS positioning system.

Background Art

[0002] Conventional GNSS receivers have mainly used the "L1" signal, which is a signal transmitted in the L1 frequency band (center frequency 1.57542 GHz). Many modern civilian GNSS receivers can receive signals in the "L5" band (center frequency 1.17645 GHz), and this band has become more popular in recent years as the number of satellites transmitting within this band has increased.

[0003] Signals transmitted in the L5 band offer several advantages over L1 signals when used in GNSS applications for navigation and tracking. The bandwidth of the L5 signal is 10 times that of the L1 signal (the chipping rate of the GPS L5 signal is 10.23 Mcps compared to 1.023 Mcps for a typical GPS L1 C / A signal), which can provide an improvement in processing gain and positioning accuracy. L5 signals are also transmitted with more power than L1 signals, and furthermore, their lower frequencies can improve reception for indoor applications.

[0004] However, the increase in the chipping rate of the L5 signal means that a higher sampling rate is required in the receiver than for the L1 signal. This means that the processing of the L5 signal is more computationally intensive than that of the L1 signal and requires more processing power and battery resources. This is particularly a problem when the positioning system is implemented on a user device such as a modern smartphone where processing power and battery resources are limited.

[0005] Furthermore, in difficult positioning environments where reflections are common, the fundamental problem remains that the L5 signal still suffers from the multipath effect. The multipath effect occurs, for example, as a result of reflections in high buildings in so-called "urban canyons", where signals from a satellite (or other remote source) take an indirect non-line-of-sight (NSL) path from the satellite to the receiver. The multipath effect causes two main problems. First, the reflected signal from the satellite may have a higher absolute power than the desired line-of-sight (SL) signal, in which case the receiver may undesirably lock onto the NSL signal. The pseudorange is incorrectly calculated due to the extra path length of the NSL signal compared to the desired SL path. Second, the NSL signal may interfere (e.g., constructively or destructively) with the SL signal at the receiver, affecting the receiver's ability to accurately process the received signal. These problems remain even with the improved processing provided by the L5 signal.

[0006] Similar problems exist in wireless communication systems other than GNSS positioning systems, such as Wi-Fi, cellular, and other wireless systems that process multiple signals at different frequencies with different signal characteristics (e.g., different bandwidths) typically broadcast from the same transmitter.

[0007] Therefore, it is desirable to overcome these problems. SUMMARY OF THE INVENTION

[0008] According to a first aspect of the present invention, there is provided a method for execution in a wireless communication system, the method comprising: generating a first local signal; receiving, at a receiver, a first signal from a remote source; determining the movement of the receiver; generating a first correlation signal by correlating the first local signal with the received first signal; providing motion compensation for at least one of a first local signal, a received first signal, and a first correlation signal based on a determined motion of a receiver along an axis of interest, thereby generating a first motion-compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal was received along the axis of interest; after determining that the first signal was received along the axis of interest, generating a second local signal, the second local signal having at least one parameter based on the first signal received along the axis of interest; receiving, at the receiver, a second signal along the axis of interest; processing the second signal received using the second local signal to determine a metric of interest associated with the receiver and / or associated with a communication link including the receiver; comprising.

[0009] In this way, embodiments of the present invention can be used to determine that a signal has been received along an axis of interest (which is typically, as further described below, the direction of a straight line, or "line of sight", between a receiver and a remote source) before investing resources in processing a second signal. In this way, processing of the second signal can be performed reliably following a determination that a signal from a remote source has been received along the axis of interest (e.g., at least one component of a signal transmitted from a remote source is received at the receiver along the axis of interest).

[0010] The first and second signals typically have different signal characteristics. The signal characteristics of the first and second signals are preferably such that it is advantageous to process the first signal to determine if it has been received along a direction of interest before investing resources in processing the second signal to determine a desired metric of interest. Examples of signal characteristics may include sampling rate, bandwidth, signal-to-noise ratio, and encryption characteristics. The first and second signals typically have substantially the same or similar propagation mechanisms and attributes.

[0011] In one embodiment, the second signal has a higher sampling rate than the first signal. Typically, the second signal has a higher bandwidth than the first signal. For example, the second signal may have a higher chipping rate than the first signal. Typically, the first signal has a longer coherence length (1 / bandwidth) than the second signal. Thus, embodiments of the present invention can utilize the reduced processing requirements associated with the first signal to determine if a signal has been received along a direction of interest before investing computational resources in processing the second signal received along the direction of interest. In this way, the present invention advantageously minimizes power consumption (e.g., extends battery life) while utilizing the enhanced signal characteristics (e.g., higher sampling rate and / or bandwidth) of the second signal in determining the metric of interest. In an exemplary embodiment, the first signal may be a GPS L1 C / A signal and the second signal may be a GPS L5 signal. However, generally, embodiments of the present invention may be applied to signals other than GNSS positioning signals (e.g., wireless) signals. For example, embodiments of the present invention may be applied, inter alia, to WiFi, cellular, Bluetooth® Low Energy (BLE) signals that represent multiple frequency channels broadcast by the same remote source (or co-located remote sources). For example, the first signal received may be a low bandwidth 3G signal transmitted from a cellular mast. Once it is determined that the 3G signal has been received along the direction of interest, the high bandwidth 4G signal received along the direction of interest can be reliably processed.

[0012]

[0012] In some embodiments, the first signal may have a higher signal-to-noise ratio (SNR) than the second signal. Thus, it may be advantageous to use the higher SNR first signal to determine that signals from the remote source are received along the direction of interest before processing the second signal.

[0013]

[0013] In further embodiments, at least one of the received signals is encrypted. For example, the first signal may be an encrypted signal indicating that the remote source can be trusted. In such an example, the second signal is typically not encrypted.

[0014] Typically, the first and second signals are transmitted on different frequency channels.

[0015] In typical embodiments, the first signal is in a first frequency band and the second signal is in a second (e.g., different) frequency band. The first and second frequency bands are typically radio frequency bands. In one embodiment, the first and second signals are GNSS positioning signals. Typically, the first frequency band is the GPS L1 band and the second frequency band is the GPS L5 band. In another example, the first signal may be a WiFi signal in the 2.4 GHz frequency band and the second signal may be a WiFi signal in the 5 GHz frequency band.

[0016] In embodiments where the first and second signals are in the first and second frequency bands respectively, the receiver is typically configured to receive signals in two or more frequency bands. Embodiments of the present invention may utilize a single receiver (e.g., the receiver is a single receiver module or includes a single receiver module) configured to receive signals in both the first and second frequency bands. Such a receiver may be referred to as a "dual band" or "multi band" receiver. In an alternative embodiment, the receiver may comprise first and second receiver modules (e.g., separate) configured to receive signals within the first and second bands respectively.

[0017] As described, preferably, the direction of interest is the straight-line direction between the receiver and the remote source (e.g., from where the first signal is received). This may be referred to as the "line of sight" (LOS) direction between the receiver and the remote source, which may be defined as the shortest distance between the receiver and the remote source without reflection. The approximate LOS direction may be approximately known, for example, by broadcast ephemeris or almanac data when the remote source is a positioning (e.g., GNSS) satellite. This is particularly advantageous when using embodiments of the present invention to generate a solution for navigation or tracking such that the metric of interest is determined from processing the LOS signal using the second signal. However, in general, it is assumed that the direction of interest can be any other direction along which a signal from the remote source is received, for example, following reflection of the signal from a building. This can be useful, for example, when it is desired to analyze the entire signal environment of the receiver.

[0018] In a typical embodiment, the second signal is transmitted from the same remote source as the first signal. For example, both signals are transmitted from the same positioning satellite, communication base station, or access point. (It should be noted that in practice, the first and second signals may be broadcast from dedicated antennas located at the same remote source, e.g., separate antennas located at the same satellite or base station.) However, the first and second signals may be transmitted from separate substantially co-located remote sources, e.g., from respective positioning satellites within the same area of the sky, such that the second signal is received along the direction of interest and thus is assumed to have substantially the same angle of arrival at the receiver as the first signal (e.g., the angles of arrival of the first and second signals at the receiver differ by less than 2 degrees, preferably less than 1 degree).

[0019] After a determination that a first signal has been received along a direction of interest (e.g., LOS), a second local signal is generated. The second local signal has at least one parameter based on the first signal received along the direction of interest. Thus, the second local signal has at least one parameter determined during processing of the first signal. In this way, the computational resources required to process the second signal are dramatically reduced compared to attempting to acquire and track the second signal without the information obtained by processing the first signal within the first frequency band. By generating the second local signal in this way, it is possible to proceed directly to tracking the second local signal. In some embodiments, the system may not perform any processing of the received second signal (e.g., without correlation) until it is determined that the first signal has been received along the direction of interest.

[0020] Typically, in embodiments where the first signal is in a first frequency band and the second signal is in a second frequency band, the first local signal corresponds to the first frequency band and the second local signal corresponds to the second frequency band.

[0021] Typically, at least one parameter of the second local signal is at least one (preferably both) of the expected symbol phase or (e.g., Doppler) frequency of the second signal received along the direction of interest. These parameters are determined based on the characteristics of the received first signal.

[0022] In an exemplary embodiment, the method further includes determining at least one characteristic of a first signal received along a direction of interest, wherein at least one parameter of a second local signal is based on the at least one characteristic of the first signal. Typically, the at least one characteristic of the first signal is at least one (typically both) of the sign phase and frequency of the first signal, and the at least one parameter of the second local signal is at least one (typically both) of the predicted sign phase or frequency of a second signal received along the direction of interest (e.g., based on the corresponding characteristic of the first signal).

[0023] These parameters may be used to track a second signal received along the direction of interest at the sign phase and frequency predicted by the processing of the first signal. This means that the system does not need to perform a search over the entire sign phase and frequency space to acquire and subsequently track the second signal, thereby advantageously reducing the processing power required by the system and improving battery life. This is particularly beneficial in embodiments where the second signal requires a higher sampling rate than the first signal, as described above. Once the second signal has been processed, the processing (e.g., tracking) of the first signal can be stopped, which can further improve processing and battery performance. If the second signal is lost, the method may be restarted (e.g., iteratively) based on the processing of the first signal.

[0024] In embodiments where the first and second signals are within respective first and second frequency bands, it will be appreciated that it is necessary to appropriately transform the characteristics of the first signal from the first frequency band to the second frequency band in order to determine the corresponding parameters of the second local signal. However, such a transformation significantly reduces the processing resources required compared to processing the second signal without the information obtained during processing in the first band. Such a transformation may be performed based on the known difference between the nominal (center) frequencies of the first and second frequency bands.

[0025] As described above, the determination that the first signal is received along the direction of interest is based on a first motion-compensated correlation signal generated by correlating a first local signal with a first received signal to generate a first correlation signal and providing motion compensation for at least one of the first local signal, the received first signal, and the first correlation signal based on the determined motion of the receiver along the direction of interest. Motion compensation can be provided using techniques known in the art, some of which are further described herein.

[0026] Typically, the determination of the motion of the receiver is performed based on measurements that can determine position or motion obtained from one or more sensors, such as inertial sensors. Examples of such inertial sensors include accelerometers (typically configured to measure linear acceleration) and gyroscopes (typically configured to measure rotational speed). The inertial sensors may be part of an inertial measurement unit (IMU). Other examples of sensors that can be used to determine the motion of the receiver include magnetometers (usually configured to measure an azimuth reference), pressure sensing devices such as barometers (usually configured to measure changes in altitude), LIDAR, RADAR, or a positioning system based on a camera or visual odometer. In some embodiments, the determination of the motion of the receiver may be assumed or predicted based on the previous motion of the receiver, as described herein.

[0027] By performing motion compensation based on the determined motion of the receiver along a particular direction (e.g., a component of the motion of the receiver along a particular direction), the gain of the signal received along that direction (e.g., either the LOS direction or the reflection direction of interest) can be higher than the gain of the signals received in other directions. In this way, the motion-compensated correlation signal for a particular direction is sensitive to the energy arriving from that particular direction. This directivity provided by performing motion compensation can be used to determine whether the first signal is received along the direction of interest.

[0028] Thus, the determination that the first signal is received along the direction of interest (e.g., at least one component of the first signal is received along the direction of interest) is typically based on the signal quality metric of the first motion-compensated correlation signal. The signal quality metric may be the signal-to-noise ratio of the first motion-compensated correlation signal. The signal quality metric typically indicates the signal power received along the direction in which motion compensation is applied. When determining whether the first signal is received along the direction of interest, the overall signal strength of the received signal may also be taken into account.

[0029] For example, if the SNR of the first motion-compensated correlation signal is greater than a predetermined threshold, this indicates that the first signal is received along the direction of interest even if there are components of the same signal reaching the receiver from other directions (e.g., following one or more reflections). Conversely, if the SNR is below the predetermined threshold (e.g., the SNR is about 1 or less), this indicates that the first signal is not received along the direction of interest, especially if the overall signal strength at the receiver is high. In the case of GNSS signals, an unobstructed LOS signal from a satellite to the ground may be expected to have a specific carrier-to-noise density (C / N0) (e.g., 40 dBHz) for a given system, and thus the measured C / N0 value of the motion-compensated correlation signal can be compared to such an expected value (e.g., a predetermined threshold) to indicate whether the first signal is received along the direction of interest (e.g., without reflections).

[0030] In some embodiments, the method further includes generating one or more additional first motion-compensated correlation signals based on the determined motion of the receiver along one or more corresponding additional (e.g., different from the direction of interest) directions, and the determination that the first signal is received along the direction of interest is based on the plurality of first motion-compensated correlation signals. In this way, motion compensation can be used to measure the relative strength of signals arriving from different directions (e.g., based on the signal quality metric of each motion-compensated correlation signal).

[0031] The plurality of first motion compensation correlation signals may have relatively large or small signal-to-noise or C / N0 values depending on the direction in which motion compensation is applied relative to the direction in which the first signal is received. This information may be used to increase the reliability with which a determination is made that the first signal was received along the direction of interest. In an embodiment, the plurality of motion compensation correlation signals may be generated substantially simultaneously (e.g., for the same epoch of the received signal). This may be achieved by providing a plurality of motion compensation processes for each of the different directions substantially simultaneously. In this way, a single epoch of the received signal may be used to generate a plurality of different signal strength values and to reveal the energy arriving from each of the plurality of different directions.

[0032] In an embodiment, the method further includes determining whether the received first signal includes a component received in a direction different from the direction of interest. This may be determined based on the plurality of motion compensation correlation signals indicating the relative strengths of signals arriving from different directions, as described above. In some embodiments, such determination may be based on a signal quality metric (e.g., signal-to-noise ratio) of the first motion compensation correlation signal and the signal strength of the first signal. For example, if the direction of interest is the LOS direction and the received first signal includes a large reflected component, the motion compensation correlation signal in the LOS direction may indicate a small signal-to-noise ratio even when the total power of the received signal (e.g., the total power received by the antenna) is high. This indicates the presence of a reflected component.

[0033] In some embodiments, the method may include determining (e.g., determining that the receiver has a "line of sight" to the remote source) that the received signal does not include a reflected component. Such a determination step is typically performed prior to the generation of the second signal. In other words, the second signal may be generated after a determination that the received signal does not include a reflected component.

[0034] Accordingly, embodiments of the present invention can analyze the signal environment of a receiver by using motion compensation to analyze a first signal (e.g., received within a first frequency band). Using motion compensation in this way is particularly advantageous because it can make a determination that the first signal was received along the direction of interest without using a 3D map that helps predict the presence of reflected signals. This is advantageous because embodiments of the present invention do not require the creation or access of a large database of topographic (e.g., three-dimensional) maps (which may be 3D city maps) or building data, which are required in such 3D map-assisted techniques.

[0035] When it is determined that the first signal from the remote source was received along the direction of interest, typically the straight-line direction between the receiver and the remote source, the second signal received along the direction of interest can be processed reliably. This ensures that the positioning system does not waste processing or battery resources by searching for or tracking the second signals when in fact the second signals are not being received along the direction of interest. This can improve the performance of the system while maximizing battery performance (e.g., by processing the second signals to determine receiver-related metrics of interest such as position or velocity when it is known that the second signals were received along the line of sight).

[0036] On the other hand, if it is determined that the first signal was not received along the direction of interest, the method typically does not perform the steps of generating a second local signal, receiving the second signal, and processing the received second signal.

[0037] As described above, in some embodiments, the second signal has a sampling rate (e.g., a higher chipping rate) that is greater than the first received signal. Since the reduced sampling rate provides a wider coverage of the search space within the correlation cycle, it is more advantageous to use the first signal to determine whether the signal was received along the direction of interest. For example, if the first signal is a GPS L1 C / A signal and the second signal is a GPS L5 signal, the early, prompt, and late (separated by half a chip) correlations of the L1 signal can cover a search space of about 100 m, while for the L5 signal, the search covers a search space of about 10 m. Thus, the L1 (e.g., reduced bandwidth) signal is advantageous for determining whether a signal from a particular remote source was received along the direction of interest.

[0038] The method includes processing the second signal received using a second local signal to determine a metric of interest related to the receiver and / or to a communication link including the receiver. For example, the second signal is typically correlated with the second local signal, and the resulting correlation signal is used to determine the metric of interest.

[0039] The metric of interest related to the receiver may be the position, velocity, time, or direction of movement of the receiver (e.g., a “physical” metric related to the receiver). The metric of interest related to the receiver is typically used to determine a solution for receiver tracking or navigation. In such embodiments, the wireless communication system is typically a positioning system or part of a positioning system.

[0040] Accordingly, in a preferred embodiment, the present invention provides a method for being executed in a positioning system, the method comprising: generating a first local signal; at a receiver, receiving a first signal from a remote source (e.g., the first signal is a GPS L1 C / A signal); determining a movement of the receiver; generating a first correlation signal by correlating the first local signal with the received first signal; providing motion compensation for at least one of the first local signal, the received first signal, and the first correlation signal based on the determined movement of the receiver along a direction of interest, thereby generating a first motion-compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal is received along the direction of interest; after determining that the first signal is received along the direction of interest, generating a second local signal, the second local signal having at least one parameter based on the first signal received along the direction of interest; at the receiver, receiving a second signal along the direction of interest (e.g., the second signal is a GPS L5 signal); and processing the received second signal using the second local signal to determine a metric of interest associated with the receiver (e.g., the metric of interest is at least one of a position, a velocity, a time, or a direction of movement of the receiver).

[0041] The second signal may be processed (using the second local signal) to determine a metric of interest associated with a communication link including the receiver. The communication link may be, for example, a cellular telecommunications link (e.g., a 3G, 4G, or 5G communication link), or a Wi-Fi or Bluetooth data communication link. Examples of metrics of interest that may be determined by processing the second signal and associated with the communication link include channel estimation parameters (e.g., channel state information), frequency selectivity, quality of service, signal availability, and quality of the communication channel between the receiver and the remote source.

[0042] In some embodiments, the processing of the second signal comprises generating a second correlation signal by correlating a second received signal with the second local signal; providing motion compensation for at least one of the second local signal, the second received signal, and the second correlation signal based on a determined motion of the receiver along the direction of interest, thereby generating a second motion-compensated correlation signal (e.g., providing a priority gain as compared to components received in a direction other than the direction of interest for the second signal received along the direction of interest); including. In such an embodiment, the generation of the second motion-compensated correlation signal is performed during a second period that is later than a first period during which the first motion-compensated correlation signal is generated.

[0043] By performing motion compensation based on a determined motion of the receiver along the direction of interest, the methods of the various embodiments can advantageously provide a priority gain for a second signal received along the direction of interest. The highest correlation can be achieved for the signal in the direction of interest even when the absolute power of this signal is less than the absolute power of signals received not along the direction of interest (e.g., non-LOS signals). The use of motion compensation can also advantageously increase the period of coherent integration of the received signals, thereby improving the ability of a system to detect very weak signals such as GNSS signals received indoors or LOS signals that have passed through a building. In some configurations, an integration time of about one second or more may be required to effectively detect weak signals.

[0044] Therefore, performing motion compensation on the received second signal can advantageously further improve the accuracy of the metric of interest regarding the receiver and / or communication link determined using the second signal, for example, by reducing the multipath effect. Such embodiments are particularly advantageous when the processing of the first signal determines that the received first signal includes components in a direction different from the direction of interest, for example, reflected signals that are not LOS, and / or when the signal received along the direction of interest is weak (e.g., due to attenuation by a building). On the other hand, if it is determined that the first received signal does not include a reflected component (e.g., the receiver is in a "clear sky" environment), motion compensation in the second frequency band may not be performed, thereby saving battery energy.

[0045] As further described herein, providing motion compensation advantageously compensates for changes in the phase and / or amplitude of the received signal as a result of the movement of the receiver. As described, motion compensation can be provided to at least one of the local signal, the received signal, and the correlation signal to generate a motion-compensated correlation signal. Motion compensation can be provided to the local signal before correlation to more closely match the received signal. In another configuration, motion compensation may be applied to the received signal to reduce the effect of the movement of the receiver on the received signal. Similar results can be achieved by providing partial motion compensation to both the local signal and the received signal. These techniques enable relative motion compensation to be applied between the local signal and the received signal. In some embodiments, motion compensation may be performed in parallel with correlation. Motion compensation can also be applied directly to the correlation signal.

[0046] In practice, the received signal may be processed as a complex signal including in-phase and quadrature components. The local signal may similarly be complex. The correlation signal may also be complex and can be used as a measure of the correlation between these complex signals.

[0047] Based on the determined movement in the direction of interest, it may be possible to achieve high positioning accuracy by providing motion compensation for at least one of the local signal and the received signal. In practice, the local signal and the received signal may be encoded with a periodically repeating code. In the case of GNSS signals, for example in the case of the GPS L1 C / A code, the local signal and the received signal can include 1023 pseudo-random code chips. The local signal and the received signal may be analog waveforms that can be digitized to provide values at a radio sampling rate, which means that there can be millions of values over a period of 1 ms. The correlation between the local signal digital values and the received signal digital values may be calculated by first correcting any set of values using the motion compensation phasor (described herein) for the relevant period. These data points may then be summed over the period. In practice, since this operates at the radio sampling frequency, accurate results can be generated, but it can be computationally intensive.

[0048] The motion-compensated correlation signal may be generated by providing motion compensation to the correlation signal. In such a case, the correlation result is typically obtained using one or more code words (1 ms in length and including 1023 chips in the case of the GPS L1 C / A code), and motion compensation is provided to the obtained correlation result.

[0049] In a further example, the correlation may be performed independently for each of approximately 1000 pseudo-random code chips, generating approximately 1000 complex correlation signal outputs. Next, motion compensation can be applied to these approximately 1000 correlation signal components. Finally, these signal outputs can be summed to generate a measure of correlation. This approach may provide an approximation of the results that can be achieved by motion compensation of the local signal and the received signal. However, in some applications, the loss of accuracy may be negligible and may be acceptable in order to reduce the computational load.

[0050] As described above, in embodiments of the present invention, motion compensation is performed to obtain a motion-compensated correlation signal of a received first signal (e.g., for determining LOS and non-LOS directions) and a received second signal (e.g., for generating an enhanced tracking or navigation solution based on the received second signal). In some embodiments, the motion compensation provided during the generation of the second motion-compensated correlation signal is based on the motion compensation provided during the generation of the first motion-compensated correlation signal corresponding to the direction of interest. Typically, one or more parameters for providing motion compensation during the generation of the second motion-compensated correlation signal are based on the corresponding one or more parameters for providing motion compensation during the generation of the first motion-compensated correlation signal corresponding to the direction of interest.

[0051] In other words, the determined motion compensation parameters based on the motion of the receiver used to generate the first motion-compensated correlation signal corresponding to the direction of interest may be reused or may form the basis for the motion compensation parameters used to generate the second motion-compensated correlation signal. This advantageously reduces the computational load when performing motion compensation to generate the second motion-compensated correlation signal. Such parameters may include a motion compensation phaser sequence as described below. The motion compensation parameters may be reused if it is determined that the motion of the receiver is substantially the same (e.g., within a predetermined threshold) during the first and second periods in which the respective motion-compensated correlation signals are generated. Otherwise, the motion compensation parameters are recalculated during the second period to generate the second motion-compensated correlation signal.

[0052] Typically, the step of providing motion compensation (e.g., when generating either the first motion compensation correlation signal or the second motion compensation correlation signal) includes generating a series of phasors including a plurality of phasors indicative of phase and / or amplitude changes introduced into the received signal as a result of the determined motion of the receiver (e.g., in each direction) over time (e.g., over time), each phasor including a phase angle and an amplitude, and synthesizing (e.g., mixing) the series of phasors with at least one of a local signal, the received signal, and a correlation signal. In this way, the phasors can be described as indicative of the determined motion of the receiver (e.g., in each direction).

[0053] Typically, the series of phasors is derived from the determined motion of the receiver over time. For example, each phasor within the series of phasors may indicate the determined motion of the receiver during a particular time interval. Thus, the resulting series of phasors indicates (e.g., corresponds to) the determined motion of the receiver during a period composed of individual time intervals. The motion of the receiver may be determined by measuring the motion of the receiver (e.g., using one or more measurements such as a gyroscope, magnetometer, accelerometer, velocity, step count, etc.) or by assuming the motion of the receiver based on past motion (e.g., a constant motion in a particular direction due to movement within a vehicle or a repetitive motion due to the movement of a pedestrian). Additionally, the motion may be extrapolated or calculated from previous motion in a particular environment. Machine learning techniques may be used to predict the motion of the receiver in such situations. The series of phasors may reflect the detailed motion of the receiver over time. For example, a plurality of phasors within the series of phasors may reflect the motion of the receiver while it is in the user's pocket during jogging, walking, running, or some other repetitive motion. In this example, the receiver may execute a periodic motion having peaks of acceleration corresponding to each heel strike. If motion measurements are not available or are inaccurate, the motion may be estimated (e.g., "predicted") from this repetitive motion.

[0054] Typically, the first and second local signals are each based on a local frequency or phase reference provided by a local oscillator, such as a crystal. In some embodiments, motion compensation may include correcting an error in the frequency or phase reference (e.g., when generating either the first motion compensation correlation signal or the second motion compensation correlation signal).

[0055] In some embodiments, the first and second local signals are each based on a local frequency or phase reference provided by a local oscillator, and the phaser series further indicates an error in the frequency or phase reference provided by the local oscillator. The error of the local oscillator may be determined by an offset between the local frequency or phase reference and the received frequency or received phase of the reference signal received from the oscillator reference source, the reference signal having a known or predictable frequency or phase, and the phaser series indicating the determined offset (e.g., over time). The phase angle and / or amplitude of the phaser series may be adjusted based on the determined offset (or time series of offsets). Such embodiments advantageously facilitate the removal of errors introduced into the correlation signal by the instability of the local oscillator of the positioning system. This is particularly advantageous in embodiments where the local oscillator is simple and low-cost, such as a crystal oscillator (e.g., used in consumer devices such as smartphones).

[0056] In another example, the error in the frequency or phase reference provided by the local oscillator may be determined using a plurality of phaser series that indicate a plurality of different predictions or "hypotheses" of the local oscillator error (e.g., for each particular direction of interest). The plurality of phaser series may indicate a prediction of the frequency and / or rate of change of the frequency offset of the local oscillator. In this way, a plurality of motion compensation correlation signals may be generated, and the motion compensation correlation signal indicates the maximum power corresponding to the error of the local oscillator.

[0057] In an embodiment, an error in a frequency or phase reference provided by a local oscillator is determined by processing a received first signal. For example, different hypotheses of local oscillator error may be used when generating an offset determined for a first motion compensation correlation signal, or a reference signal having a known or predictable frequency or phase. The local oscillator error determined based on the first signal may then be advantageously used during processing of the second signal. This advantageously reduces the computational resources required when processing the second signal.

[0058] In various embodiments, the phaser sequence used to generate a second motion compensation correlation signal is based on the phaser sequence used to provide a first motion compensation correlation signal corresponding to the direction of interest. For example, the phaser sequence used to generate a first motion compensation correlation signal along a direction of interest (e.g., LOS) may be stored in an addressable memory and accessed when generating the second motion compensation correlation signal. This “reuse” of the phaser sequence advantageously reduces the processing resources required to generate the second motion compensation correlation signal. The motion compensation phaser sequence may be reused if the motion of the receiver is substantially the same during processing of the first and second signals. In embodiments where the first and second signals are in different frequency bands, due to the difference in the frequency bands of the first and second signals, it will be appreciated that one or more phaser sequences need to have a transformation (e.g., an offset) applied when used for the second motion compensation correlation signal. However, the processing power required to apply such a transformation is negligible compared to regenerating the entire phaser sequence.

[0059] In this way, by basing the phaser sequence used to generate the second motion compensation correlation signal on the phaser sequence used to provide the first motion compensation correlation signal, information determined during processing of the first signal (e.g., an error in a frequency or phase reference provided by a local oscillator) may be advantageously used in processing the received second signal, thereby reducing the computational load.

[0060] As a further advantage provided by embodiments of the present invention, generating a second local signal having at least one parameter based on a first signal received along a direction of interest can track a second signal (e.g., within a second frequency band) that may be too weak to be directly acquired due to the environment (e.g., the second signal may pass through a building between a remote source and a receiver) or due to the receiver's antenna (e.g., an antenna without sufficient gain). In other words, the direction information regarding where to track the second signal obtained from the analysis of the first signal can mean that it may be possible to track the second signal that otherwise could not be acquired. Using motion compensation to enhance the gain of the second signal received along the direction of interest (in the analysis of the first signal and optionally also in subsequent processing of the second signal) advantageously means that it may be possible to detect and track the second signal using an antenna not specifically designed for such a signal. This advantageously means that lower quality or less expensive antennas can be used, or existing antennas within the system (e.g., cellular antennas) can be "reused". Thus, the number of antennas within the system can be reduced. This can be particularly advantageous when the system is implemented on a consumer electronic device such as a modern smartphone.

[0061] For example, when the first signal is a GPS L1 C / A signal, the second signal is a GPS L5 signal, and the (e.g., positioning system) is implemented on a smartphone, instead of requiring a separate L5 antenna, the gain and sensitivity improvements provided by the present invention can make it possible to "reuse" a cellular antenna for tracking the L5 signal.

[0062] According to a second aspect of the present invention, there is provided a computer program product including executable instructions that, when executed by a processor in a wireless communication system, cause the processor to execute any of the steps of the embodiments of the first aspect described above.

[0063] Disclosed herein is a non-transitory computer-readable medium including executable instructions that, when executed by a processor in a wireless communication system, cause the processor to execute any of the steps of the embodiments of the first aspect described above.

[0064] Further disclosed herein is a wireless communication system including a receiver (configured to receive signals from a remote source, for example) and one or more processors configured to execute the method according to any of the above examples.

[0065] According to a third aspect of the present invention, there is provided a wireless communication system including a receiver (configured to receive signals from a remote source, for example), a motion unit configured to determine the motion of the receiver, and one or more processors, the processor generating a first local signal; receiving, at the receiver, a first signal from a remote source; determining the motion of the receiver; generating a first correlation signal by correlating the first local signal with the received first signal; providing motion compensation for at least one of the first local signal, the received first signal, and the first correlation signal based on the determined motion of the receiver along a direction of interest, thereby generating a first motion-compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal is received along the direction of interest; After determining that the first signal has been received along the direction of interest, generating a second local signal, the second local signal having at least one parameter based on the first signal received along the direction of interest; In a receiver, receiving a second signal along the direction of interest; Processing the second signal received using the second local signal to determine a figure of merit associated with the receiver and / or a communication link including the receiver; configured to perform.

[0066] Accordingly, the system of the third aspect provides all of the above advantages. In general, one or more processors may be configured to perform any of the method steps described above.

[0067] One or more processors are typically further configured to perform a step of determining at least one characteristic of the first signal received along the direction of interest, and at least one parameter of the second local signal is based on at least one characteristic of the first signal. Typically, as described above, at least one characteristic of the first signal is at least one (preferably both) of the sign phase and frequency of the first signal, and at least one parameter of the second local signal is at least one (preferably both) of the expected sign phase or frequency of the second signal received along the direction of interest (e.g., within a second frequency band).

[0068] In various embodiments, one or more processors are further configured to determine whether the first signal received includes a component received in a direction different from the direction of interest.

[0069] In various embodiments, one or more processors generating a second correlation signal by correlating the second local signal with the second signal received; Based on the determined movement of the receiver along the direction of interest, providing motion compensation for at least one of the second local signal, the received second signal, and the second correlation signal, thereby generating a second motion-compensated correlation signal (e.g., providing a priority gain for the second signal received along the direction of interest compared to the components received in a direction other than the direction of interest). It is further configured to perform.

[0070] In various embodiments, the system further comprises an addressable storage device configured to store one or more parameters for providing motion compensation during the generation of the first motion-compensated correlation signal corresponding to the direction of interest. Such parameters may be reused (e.g., using appropriate transformations) when generating the second motion-compensated correlation signal using the received second signal, advantageously reducing battery resources.

[0071] Typically, one or more processors are configured to generate a series of phasors including a plurality of phasors indicative of phase and / or amplitude changes introduced into the received signal as a result of the determined movement of the receiver, each phasor including a phase angle and an amplitude, and the series of phasors is combined with at least one of the local signal, the received signal, and the correlation signal.

[0072] Typically, the system further comprises a local oscillator configured to provide a local frequency or phase reference (e.g., for the generation of the first and second local signals). In an embodiment, the series of phasors further indicates an error in the frequency or phase reference provided by the local oscillator. In this way, the mobile receiver can provide a coherent integration of signals that is longer than would otherwise be possible, as described above.

[0073] Typically, the receiver is configured to receive signals in two or more frequency bands.

[0074] The wireless communication system described in this specification is typically a positioning system, preferably a GNSS positioning system. In an embodiment, the system may be a cellular communication system, or a communication system such as a Wi-Fi or Bluetooth communication system.

[0075] The system is typically provided on a single user device such as an electronic user device like a positioning device or a smartphone. Alternatively, the various units within the system can be provided separately to decentralize the system (i.e., configured as a distributed system). For example, certain calculations may be performed by a processor within the network. Thus, the electronic user device may offload calculations to other processors within the network when appropriate for efficiency.

[0076] One or more remote sources from which signals are received are typically trusted remote sources (such as GNSS positioning satellites) from which received data can be trusted, i.e., assumed to be correct. The received signal may include any known or unknown pattern of transmitted information, either digital or analog, that can be found within the broadcast signal by a cross-correlation process using a local copy of the same pattern. The received signal may be encoded with a chipping code that can be used for ranging. Examples of such received signals include GPS signals that include Gold codes encoded within the wireless transmission. Another example is the extended training sequence used in GSM (registered trademark) cellular transmissions. In a further example, the received signal may include a pilot symbol sequence that can be used for correlation, such as those used in orthogonal frequency division multiplexing (OFDM), long term evolution (LTE), and digital video broadcasting (DVB) standards.

[0077] In various embodiments of the present invention where the first and second signals are in different frequency bands, the second frequency band is typically the L5 GNSS frequency band. Preferably, the first frequency band is the GNSS L1 frequency band.

[0078] In any of the aspects of the present invention, the receiver may be a GNSS receiver. The receiver may be implemented on an electronic user device such as a smartphone. The remote source is typically a GNSS satellite. However, as discussed, the present invention may also be applicable to other (e.g., wireless) signals such as cellular, DAB or DVB, Wi-Fi or Bluetooth signals received from each remote source.

[0079] In embodiments, the determined metric of interest associated with the receiver and / or the communication link including the receiver may include one or more of the position of the receiver, the speed of the receiver, the direction of movement of the receiver, the time at the receiver, the tracking or navigation solution of the receiver, one or more channel estimation parameters, channel frequency selection parameters, quality of service metrics, signal availability metrics, quality metrics of the communication channel between the receiver and the remote source. Embodiments of the present invention may also be used to improve the reception of signals, as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Next, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0081] The following description focuses on embodiments of the present invention implemented in a positioning system in which the processed signal is a GNSS positioning signal to determine, for example, the position, velocity, and / or time associated with a receiver. However, the techniques taught herein can be applied in other wireless communication systems to process other (e.g., wireless) signals such as cellular, WiFi, etc. to determine other metrics of interest, as discussed herein.

[0082] FIG. 1 shows, by way of example, a schematic view of an environment in which a positioning device 1000 is positioned within an "urban canyon" environment located between tall buildings 50a, 50b where wireless signals including GNSS signals from a remote source can be reflected. Such an "urban canyon" environment is typically an environment in which it is difficult for a positioning system to accurately determine a position solution due to reflection and multipath effects.

[0083] In the example of FIG. 1, the positioning device 1000 receives signals from GNSS positioning satellites 200a, 200b that are part of a global positioning system (GPS) constellation in this example. However, it will be understood that embodiments of the present invention may be used with other GNSS systems such as GLONASS, Galileo or Beidou systems. The positioning device receives a GPS L1 signal from a first satellite 200a along a straight line (SL) direction D1, which may be referred to as the "line of sight" (LOS) direction between the device and the satellite. Also, the signal from the first satellite 200a includes a reflected component D2 that is reflected off the surface of building 50a and reaches the positioning device. The positioning device also receives an L1 signal including a strong reflected component D4 from a second satellite 200b. However, as schematically shown in FIG. 1, the signal from the second satellite 200b is not received by the positioning device 1000 along the LOS direction D3 because this component is blocked by building 50b.

[0084] The positioning satellites 200a, 200b also transmit signals within the GPS L5 band, and it is desirable to receive and process these signals in order to utilize the characteristics of the L5 signals for improved navigation and tracking solutions compared to the GPS L1 signal. The path of the L5 signal between the satellite and the positioning device 1000 is the same as described above for the L1 signal. FIG. 1 shows some of the challenges faced by a positioning system when attempting to determine a navigation or tracking solution in a difficult environment such as the illustrated urban canyon. The LOS and reflected components of the broadcast signal from satellite 200a reach the positioning device via different paths as shown by D1 and D2, and thus are received at different times and, in some cases, with different attenuation and phase characteristics. Accordingly, the LOS and reflected components of the signal received from satellite 200a act as noise with respect to each other (e.g., via constructive interference and / or destructive interference), which can cause significant problems for positioning accuracy.

[0085] Furthermore, the signal from satellite 200b is only received at the positioning device 1000 after reflection (since the LOS direction is blocked by building 50b). A conventional multi-band system may determine that the L1 signal from satellite 200b is received with power above a predetermined threshold and thus may proceed to reliably process the L5 signal from satellite 200b in order to utilize the improved processing and positioning accuracy provided by such a signal. However, due to the reflected nature of the received signal, the navigation and tracking solutions generated using the L5 signal may remain in error even if the tracking and navigation solutions may potentially be reported reliably.

[0086] Embodiments of the present invention seek to overcome these problems.

[0087] FIG. 2 is a schematic diagram showing relevant parts of a positioning system (e.g., implemented in a single positioning device 1000 as shown in FIG. 1) according to an embodiment of the present invention. The receiver schematically shown at 100 includes or is coupled to an antenna 2 configured to receive radio frequency signals such as GNSS signals as described above. In particular, the antenna 2 is configured to receive radio frequency signals in two or more distinct radio frequency bands (although it is contemplated that the receiver may include or be coupled to a separate dedicated antenna for each frequency band). In this embodiment, the antenna can receive signals in both the L1 frequency band (1.57542 GHz) and the L5 frequency band (1.17645 GHz). Typically, the broadcast signals received by the antenna 2 are analog signals, which are amplified, down-converted to baseband or a lower frequency, and converted to digital form by an analog-to-digital converter. These processes are typically performed in the receiver. The positioning device 1000 can be a stand-alone device or can be implemented in an electronic consumer device such as a smartphone.

[0088] As schematically shown in FIG. 2, the positioning system includes signal processing channels for different frequency bands. In this embodiment, the system includes a plurality of channels configured to process signals received within the L1 frequency band (e.g., from different satellites) and a plurality of channels configured to process signals received within the L5 frequency band, as schematically shown in FIG. 2. In the following description, reference is made to the processing of signals on the L1 channel, but the corresponding description applies to the processing performed on the L5 channel.

[0089] The received L1 signal is correlated in a correlation unit 12-1 with a local replica of that signal generated by a local signal generator 8-1. The correlation unit comprises a correlator. The local signal generator 8-1 is configured to generate a local copy of a known correlation sequence (such as a pseudo-random number (PRN) code for a GNSS satellite) using the frequency or phase reference of a local oscillator 10. The local signal generator is typically a frequency synthesizer. The local oscillator 10 is generally simple and low-cost, especially when the positioning device is implemented on a handheld electronic device such as a smartphone. For example, the local oscillator 10 may comprise a crystal.

[0090] The motion unit 4 includes sensors that can measure the motion of the receiver 100, particularly the motion of the antenna 2. The motion unit 4 can include inertial sensors such as an accelerometer and a gyroscope, and data therefrom may be used to infer the motion of the receiver. The motion unit 4 typically comprises an inertial measurement unit (IMU) that uses inertial sensors, although other (non-GNSS) means for determining the motion of the receiver, such as a barometer, a magnetometer, and a visual odometry system, may be used alternatively or additionally. In some embodiments, the motion unit 4 may include a trained machine learning model that can predict the motion of the receiver.

[0091] The motion compensation unit 20 derives a motion compensation phasor indicative of the amplitude and / or phase change introduced into the received signal as a result of the determined motion of the receiver determined by the motion unit 4. The motion compensation phasor may be applied to at least one of the local signal from the local signal generator 8-1, the received signal, and the correlation signal from the correlation unit 12-1. The phasor generated by the motion compensation unit 20 may be stored in a storage device 17 (e.g., a memory) for use in a subsequent period.

[0092] After acquisition, the updated estimated values of the sign phase and frequency of the received signal may be fed back to the local signal generator 8-1 to track the received signal. Such a "tracking loop" may be a delay lock loop (DLL) for tracking the sign phase of the input signal, and a phase lock loop (PLL) or a frequency lock loop (FPP) for tracking the carrier wave, as is known in the art.

[0093] The signal analysis unit 14 analyzes the output of the channel motion compensation correlation to provide a navigation or tracking solution, as will be described in more detail herein.

[0094] Each of the above units of the positioning system logically communicates with a processor 1 operable to control the operation of the various units according to the executed software or firmware. In the illustrated embodiment, the units (or "modules") are provided within a single positioning device 1000. It will be understood that the illustrated arrangement of the various units is merely exemplary, and the units may be arranged according to the device in which the system is implemented, as needed. In an alternative embodiment, the various units of the system may be provided distributed across a network.

[0095] FIG. 3 is a flowchart showing an overview of the main steps of an embodiment of the present invention, and will be described with reference to the positioning device and environment shown in FIGS. 1 and 2. In step S100, the receiver 100 receives a GPS L1 signal from a satellite, for example, the positioning satellite 200a. As described above, the signal received by the receiver includes a component that has traveled along the straight line between the receiver and the satellite, as well as a component that has been reflected in a non-linear direction. The following description of FIG. 3 is mainly based on the processing of the positioning signal received from the satellite 200a, but it will be understood that the steps of the flowchart may be executed for any remote source (or co-located remote source) from which signals in two frequency bands can be received.

[0096] In step S102, the motion unit 4 determines the motion of the receiver 100. The motion unit 4 may measure the motion of the receiver by using data obtained from inertial sensors as part of the IMU, for example, by integrating acceleration measurements from an accelerometer to estimate the speed of the receiver. The motion module may estimate (``predict'') the motion of the receiver based on the motion pattern in the previous epoch. For example, if the previous measurements indicate that the receiver 100 is moving in a certain direction and at a certain speed, it may be assumed that the current motion is the same as the motion in the previous period. This is particularly applicable in situations where the motion is likely to remain substantially the same, for example, when the receiver is placed inside a moving vehicle or held by a jogger. By assuming the motion of the receiver over an appropriate period, the processing load may be reduced and battery resources may be conserved. The motion unit 4 may calculate the motion based on the past motion at a specific time of day, or may use machine learning, for example, a recurrent neural network, to predict the motion from past motion data.

[0097] In step S104, the motion compensation unit 20 receives the determined motion of the receiver from the motion unit 4 and generates a phase series according to the motion of the receiver in the line-of-sight (straight line) direction D1 between the receiver and the satellite 200a. (In this example, the direction of interest is the line of sight, the LOS direction, but it should be noted that, as explained, the direction of interest may be a direction other than the line of sight.) Thus, referring back to FIG. 1, with respect to the signal received from the satellite 200a, the motion compensation unit 20 is configured to construct a phase series indicating the motion of the receiver along the LOS direction D1. Similarly, when processing the signal from the satellite 200b, the motion compensation unit 20 is configured to construct a phase series indicating the motion of the receiver along the LOS direction D3. These linear directions may be known or estimated based on the initial estimated value of the receiver's position and the broadcast orbit data or ephemeris from the satellite constellation. The initial estimated value of the receiver's position may be determined using conventional GNSS ranging calculations based on the available signals. If available (e.g., if the system is provided in a smartphone), the initial estimated value of the position can also be determined based on cellular data. Usually, the initial estimated value of the position can be determined using conventional techniques within an accuracy better than 20 meters depending on the receiver's environment.

[0098] Each phase series φ includes a plurality of phases, and each phase typically has the same duration as the samples of the received signal. Since there are samples of the received signal and samples of the local signal during the period in which the received signal and the motion of the receiver are measured, the generated phase series φ typically has the same number N of phases φ i (I = 1..N). Each phase φ irepresents phase and amplitude compensation based on the movement of the receiver at time t such that a phaser series composed of a plurality of phasers indicates the movement of the receiver along a specific direction over time (e.g., each phaser includes a phase angle and an amplitude). In this way, each phaser series indicates changes in phase and / or amplitude introduced into the received signal as a result of the movement of the receiver. For example, the velocity of the receiver derived from the movement unit 4 may be used to determine the Doppler frequency shift introduced into the received signal due to the movement of the receiver along the line of sight direction. The Doppler frequency shift may then be integrated over time to estimate the phase value.

[0099] Therefore, the phaser series may be referred to as a "motion compensation" phaser series.

[0100] Phaser φ i is a transformation in the phase space, is a complex number value, generates the in-phase component of the motion compensation phaser series via its real number value, and generates the quadrature phase component of the motion compensation phaser series via its imaginary number value. Phaser φ i is typically a periodic phaser and may be represented in several different ways, for example, as a clockwise rotation from the real axis or as a counterclockwise rotation from the imaginary axis. As described above, the phaser series in each direction indicates the determined movement of the receiver along that direction.

[0101] Each phaser series is stored in the memory unit 17 (step S104a) and may be reused during a suitable subsequent period in which the determined movement of the receiver remains substantially constant over the period.

[0102] Referring back to FIG. 3, in step S106, a motion-compensated correlation signal is generated for the L1 signal received along the LOS direction D1 between the receiver and satellite 200a. The correlation unit 12 correlates the local signal generated by the local signal generator 8-1 of the L1 channel with the received signal, and based on the determined motion of the receiver along the LOS direction D1 determined by the motion unit 4, motion compensation is applied to at least one of the local signal, the received signal, and the resulting correlation signal. This is done by combining (e.g., mixing) the phaser sequence derived by the motion compensation unit 20 in step S104 with at least one of the received signal, the local signal, and the correlation signal.

[0103] Each phaser sequence φ may be applied to at least one of the local signal, the received signal, or the result of the correlation (e.g., the initial correlation signal). FIG. 4 is a schematic diagram showing how the phaser sequence calculated by the motion compensation unit 20 can be combined with the local signal to generate a motion-compensated correlation signal. As described above, the motion unit 4 provides the determined motion of the receiver, which is used by the phaser generation unit 20 to generate a phaser sequence indicating the motion of the receiver in the LOS direction between the receiver and the satellite. The local signal L generated by the local signal generator 8-1 is combined (e.g., mixed) with the phaser sequence generated by the motion compensation unit 20-1 (30) to generate a motion-compensated local signal shown as L-MC in FIG. 4. Next, this motion-compensated local signal L-MC is correlated with the received signal R in the correlation unit 12 (e.g., after initial processing by the receiver) to provide the motion-compensated correlation signal shown as C-MC. Then, the motion-compensated correlation signal is passed to the signal analysis unit 14. In practice, both the in-phase component and the quadrature-phase component of the phaser sequence φ are combined with the local signal to generate both an in-phase motion-compensated local signal and a quadrature-phase motion-compensated local signal for correlation.

[0104] As described herein, generally, a phase series φ may be applied to at least one of the local signal, the received signal, and the correlation signal generated by a correlator in order to perform motion compensation. FIG. 5 schematically shows providing motion compensation to the received signal R (generating a motion-compensated received signal R-MC for correlation with the local signal L), thereby generating a motion-compensated correlation signal C-MC. FIG. 6 schematically shows a process of applying motion compensation to a correlation signal (C) generated by correlating a received signal (not motion-compensated) with a local signal to generate a motion-compensated correlation signal C-MC that can be passed to the signal analysis unit 14.

[0105] The number of correction phases in the phase series φ corresponds to the number of samples of the signal to which motion compensation is applied (e.g., over the period of coherent integration). For example, both the received signal and the local signal are typically sampled at the same rate and thus have the same number of samples per second (e.g., 4 million samples per second). Thus, for example, the same phase series φ may be applied to either the local signal or the received signal to generate the same motion-compensated correlation signal. When applying motion compensation to the correlation signal following the correlation of the ( "original") local signal and the received signal, the phase series φ typically has fewer elements than when applied to the local signal or the received signal due to the typically low sampling rate of the correlation signal (e.g., about 1000 samples per second).

[0106] Further details regarding the generation of the motion compensation phase series and their use in the generation of the motion-compensated correlation signal can be found in International Publication No. WO 2017 / 163042 by the same applicant, which is hereby incorporated by reference in its entirety.

[0107] This process results in a motion-compensated correlation signal that can calculate the signal-to-noise ratio (SNR). This SNR can be used to determine whether the L1 signal was received along the LOS direction between the receiver 100 and the satellite 200a. If the SNR of the motion-compensated correlation signal in the LOS direction is greater than a predetermined threshold, the receiver 100 can infer that it is receiving a signal along the LOS direction between the receiver and the remote source. Referring again to FIG. 1, when analyzing the signal received from the satellite 200a, the receiver 100 receives both the LOS (D1) component and the reflected (D2) component of the broadcast signal, but the SNR of the motion-compensated correlation signal along the LOS direction is greater than the predetermined threshold, thereby indicating that the signal component was actually received along the LOS. In contrast, for the satellite 200b, the overall signal strength received from the satellite 200b is relatively high due to the reflected component D4, but the SNR ratio of the motion-compensated correlation signal along the LOS direction D3 is below the predetermined threshold, indicating that the LOS component is not received by the receiver (in this case, blocked by the building 50b).

[0108] Therefore, by performing motion compensation in this way, it is possible to determine whether a signal is received along the LOS direction between the receiver and each satellite (step S108). The directivity provided by the motion compensation process advantageously enables energy search to be performed along the LOS direction, enhancing the accuracy of this determination.

[0109] Optionally, in step S109, the motion compensation correlation signal may be generated for further directions other than the above-described LOS direction. This can be advantageously used, for example, to determine the signal environment of the receiver in order to establish whether a reflected signal is present. The signal analysis unit is configured to determine one or more candidate directions along which a reflected signal can be received. By generating a motion compensation phaser sequence indicative of the receiver's motion along these candidate directions and then generating motion compensation correlation signals corresponding to these directions, it can be established whether a reflected signal has actually been received along the candidate directions. Although not essential, the candidate directions may be determined using a 3D topographic model of the receiver's environment, such as a 3D city model, based on an initial estimate of the receiver's position and established facts. Such a 3D model may be stored in the memory device 17 or retrieved via the Internet or other data connection.

[0110] Continuing with the exemplary environment shown in FIG. 1, the fact established regarding satellite 200a is that there is a LOS signal because the SNR of the motion compensation correlation signal along that direction is greater than a predetermined threshold. However, the SNR may not correspond to the overall signal strength received at the receiver, indicating the presence of a reflected component. The 3D model may be used to determine candidate directions along which a reflected signal may be received at the receiver, for example, reflected from building 50a as shown in FIG. 1. When a motion compensation correlation signal for candidate direction D2 is generated, the candidate direction corresponds to the actual reflection direction and thus has a high SNR. This indicates that the signal received from satellite 200a actually contains a reflected component.

[0111] Similarly, the fact established for satellite 200b is that, due to the low SNR of the motion-compensated correlation signal along its direction, the signal is unlikely to be received along the LOS direction, but the overall signal strength received by the receiver is high. This strongly indicates the presence of a reflected component received by the receiver. Again, a 3D model may be used to perform further motion compensation and determine one or more candidate directions for generating the motion-compensated correlation signal. In this case, the motion-compensated correlation signal corresponding to direction D4 returns a very high SNR, which strongly indicates the presence of a reflected component.

[0112] In some embodiments, the system may not have access to a 3D model. In such embodiments, the signal analysis unit 14 may determine candidate directions based on an "all-sky" search. For example, a plurality of candidate directions, each defined by an azimuth angle and an elevation angle, may be determined for substantially all directions in which a signal may be received. By generating a motion-compensated correlation signal for each possible direction, the SNR ratio may be analyzed to infer the likelihood that a reflected signal is received along that direction.

[0113] Such an "all-sky" search is computationally intensive, and thus, since a full scan of the signals received by the receiver is desired, it is preferred to utilize a 3D model.

[0114] Accordingly, the method may include measuring the signal power arriving from different directions using a plurality of motion-compensated correlation signals. The plurality of motion-compensated correlation signals (and thus, the subsequent determination of the angle of arrival) may be generated substantially simultaneously by applying different phaser sequences corresponding to different candidate directions to a correlation bank. Different correlation signals are sensitive to energy arriving from different directions, even when a single omnidirectional antenna is used.

[0115] Motion compensation can be provided for each different direction by providing a phase shift between signals received at different times.

[0116] Further information regarding determining candidate directions to establish the presence of reflected signals and the signal environment of the receiver can be found in International Publication No. WO 2019 / 058119 by the same applicant, which is hereby incorporated by reference in its entirety.

[0117] Referring again to FIG. 3, when it is determined that the first signal is received along the LOS direction between the receiver and satellite 200a, at step S110, a second local signal is generated based on the characteristics of the first signal received along the LOS direction. In this example, it is recalled that the determination in step S108 is made for the L1 channel. Thus, when it is established that the L1 signal from satellite 200a is being received along the LOS, the parameters of the L5 channel can be set to reliably track the LOS L5 signal from the same satellite. In some examples, the L5 channel may not be activated until it is determined that the L1 signal is received along the direction of interest, thereby further conserving battery energy.

[0118] Accordingly, the local signal generator 8-2 for the L5 channel corresponding to satellite 200a is used to generate a local signal at the expected code phase and frequency of the L5 signal received from the same satellite 200a along the line of sight D1, based on the corresponding characteristics of the first signal received on the L1 channel along the line of sight. In other words, the L5 channel of the receiver may start tracking the LOS L5 signal from satellite 200a using the information obtained by processing the L1 signal on the L1 channel. Note that it is necessary to perform an appropriate conversion of the expected code phase and frequency to convert the results obtained on the L1 channel to results suitable for the L5 channel. The signal analysis unit 14 and the band switch unit 26 communicating with each channel are configured to provide prediction parameters (e.g., code phase and frequency) to the L5 channel based on the processing of the L1 signal and perform the appropriate conversion.

[0119] The conversion of the sign phase and frequency of the received L1 signal to those predicted in the L5 channel is performed based on the known difference between the L1 nominal frequency and the L5 nominal frequency. For example, when the Doppler shift of the L1 carrier frequency (e.g., due to the movement of the satellite and the receiver, as well as clock errors) is determined based on the processing of the L1 channel, it is possible to calculate the predicted Doppler shift correction to the nominal frequency at which the L5 signal can be detected. Similarly, by using the signal received in the L1 channel to calculate the current estimated values of the receiver's position and Time of Week, the predicted L5 sign phase can be calculated based on the current estimated values of the receiver's position and time. In this way, using the characteristics of the received first signal, predicted parameters (e.g., Doppler shift and sign phase) can be calculated to process (e.g., track) the L5 signal from the same satellite without the need for a computationally intensive acquisition process.

[0120] In this way, the present invention performs the initial acquisition and determination of the expected sign phase and frequency on the L1 signal having a lower sampling rate than the L5 signal, so that the processing load when tracking the L5 signal can be minimized and battery resources can be saved. Further, after the determination that the signal from the satellite is being received along the line of sight, the L5 signal from the same satellite can be tracked with high reliability based on the local signal generated for the L5 channel. For example, referring again to FIG. 1, after the determination that the signal from the first satellite 200a is being received along the LOS direction, the L5 signal received from the satellite 200a may be processed reliably following the generation of the L5 local signal based on the L1 processing.

[0121] Conversely, since the L1 signal from the second satellite 200b reaches the receiver only after reflection, after processing the L1 signal received from this satellite, it may lead to an incorrect solution and thus waste computational resources and battery life. Therefore, it may be determined not to attempt to track the L5 signal from satellite 200b. Thus, when processing the signal from satellite 200b, the method may end after step S109. This is in contrast to conventional systems that attempt to track the L5 signal from satellite 200b even if the received L1 signal strength is greater than a predetermined threshold, as this may simply be due to a reflected signal.

[0122] In step S112, the L5 signal from satellite 200a is received by the receiver. As explained, the characteristics of the receiver's L5 channel are set such that the received LOS L5 signal can be immediately tracked without using computational resources to search the space of code phase and frequency to acquire the signal. To further reduce the computational load, the L1 channel tracker may be stopped when the received L5 signal is being tracked.

[0123] In various embodiments, the method then proceeds to a determination step S114 based on whether any reflected components are present (e.g., after analysis of the additional motion compensation correlation signal generated in step S109). If it is determined that there are both components received along the LOS direction and reflected components for a particular satellite, the method proceeds to step S116, where the motion compensation correlation signal for the L5 signal is generated based on the determined motion of the receiver along the determined LOS direction. By providing motion compensation along the LOS direction determined between the receiver and the satellite, the resulting motion compensation correlation signal provides a priority gain compared to signals not received along the LOS direction for which motion compensation is provided. Thus, for the positioning satellite 200a of FIG. 1, the signal components received along the LOS direction D1 are advantageously provided with an increased gain compared to any reflected components present. Generating the motion compensation correlation signal in this way also helps to mitigate the multipath effect caused by the reflected components of the signal.

[0124] To reduce the computational load in this step, the motion compensation phasor series generated on the L1 channel in step S104 and stored in step S104a may be reused in step S116 to avoid the need to recalculate the phasor series. The motion compensation phasor series is reused when the motion of the receiver is substantially the same as when the phasor series was constructed. This requirement may be verified, for example, using the sensors of the motion unit 4 to confirm that there has been no change in the direction of travel or speed. On the other hand, if the data from the motion unit indicates that there has been a change in the motion of the receiver since the period during which the phasor series was constructed on the L1 channel, the motion compensation unit 20 recalculates the phasor series indicating the current motion of the receiver during a subsequent period in which processing is performed on the L5 channel.

[0125] It will be appreciated that in order to "reuse" the phasor series stored in the memory device 17, it is necessary to appropriately convert the phase value from the L1 channel to the L5 channel based on the wavelength difference between the L1 signal and the L5 signal. Such conversion may be performed in the band switch unit 26.

[0126] The method then proceeds to step S118, where the signal analysis unit 14 determines a metric of interest related to the receiver, such as position, speed, time, or direction of motion, based on the processing of the received L5 signal. The metric of interest is typically used to determine a solution for receiver tracking or navigation. The use of the L5 channel (instead of the L1 channel) in determining the metric of interest is advantageous because the bandwidth of the L5 signal is increased, allowing for an increase in processing gain and an improvement in positioning accuracy.

[0127] Alternatively, if it is determined that there is no reflection component (e.g., when the receiver is located in an "open sky" environment rather than the "urban canyon" shown in FIG. 1), the method can optionally proceed directly to step S118, i.e., no motion compensation correlation signal is generated. Since the priority gain provided by motion compensation is not very advantageous in such an open environment due to the lack of reflection signals, computing resources may be conserved by not applying motion compensation during the processing of the received L5 signal. However, in an embodiment, it may be selected to always perform motion compensation when processing the received L5 signal (i.e., independent of the receiver environment) in order to benefit from the signal gain and increased directivity provided by motion compensation.

[0128] Typically, steps S100 to S109 are executed during a first period, and steps S110 to S118 are executed during a second period that is later than the first period.

[0129] As described above, the local signals generated by the local signal generators 8-1 and 8-2 are based on the local frequency and phase reference provided by the local oscillator 10. In some embodiments, the local oscillator error unit 11 can be used to determine the offset between the local frequency or phase reference and the received frequency or received phase of the reference signal received from the oscillator reference source, where the reference signal has a known or predictable frequency or phase. In this way, the error in the local oscillator 10 can be separated by removing the effect on the received phase or received frequency along the vector between the receiver 100 and the oscillator reference source from which the reference signal is received based on the relative motion between the receiver 100 and the oscillator reference source. In such embodiments, the phaser series generated by the motion compensation unit 20 may further indicate the determined offset (e.g., as a function of time). The amplitude and / or phase angle of the phaser series generated by the motion compensation unit 20 may be adjusted based on the determined offset (or time series offset) between the local oscillator and the oscillator reference source.

[0130] Thus, in an optional embodiment, the method may include determining components of the movement of both the receiver and the oscillator reference source along a linear direction (the "line of sight") between the two. By compensating for the offset between the local frequency or phase provided by the local oscillator and the reference signal, the mobile receiver can provide a coherent integration of the signal over a longer period than would otherwise be possible. Coherent integration of the received signal over a period of one second or more is possible. This, in combination with the use of the motion compensation described above, means that the sensitivity of the receiver is improved so that weaker positioning signals can be detected and used in the positioning calculation. Such an embodiment is particularly beneficial when the local oscillator has a large instability (e.g., the crystal oscillator of a low-cost device such as a smartphone).

[0131] The oscillator reference source may be a ground transmitter. For example, the oscillator reference source may be a cellular transmitter or DAB, DVB-T, or analog broadcast. The oscillator reference source may be a satellite, e.g., a GNSS satellite having a highly stable atomic local oscillator. The oscillator reference source may be a remote source (e.g., satellites 200a, 200b in FIG. 1) from which processed L1 and L5 signals are broadcast. Importantly, the local oscillator within the oscillator remote source should be at least more stable than the local oscillator. Further details regarding the use of the reference source for determining errors in the local oscillator can be found in International Publication No. WO 2019 / 008327 by the same applicant, which is hereby incorporated by reference in its entirety.

[0132] In another example, the error in the frequency or phase reference provided by the local oscillator 10 may be determined by using multiple phaser sequences for each direction that "tests" different hypotheses of the error of the local oscillator 10. For example, in step S104, multiple phaser sequences may be generated, each of which provides motion compensation along the direction of interest, but further tests a plurality of different hypotheses of the respective frequency and / or frequency change rate errors of the local oscillator. Thus, step S106 provides a plurality of motion compensation correlation signals corresponding to the error hypotheses of the local oscillator 10, respectively. Then, the motion compensation correlation signal having the highest power indicates the hypothesis closest to the true offset or error of the local oscillator. Further details regarding "testing" different hypotheses of the local oscillator error can be found in International Publication No. WO 2019 / 063983 by the same applicant, which is hereby incorporated by reference in its entirety.

[0133] Typically, the local oscillator error unit 11 uses the received L1 signal to determine the error in the local oscillator 10 (e.g., the offset between the local frequency or phase reference and the received frequency or received phase of the reference signal received from the oscillator reference source). These offsets (or "errors") of the local oscillator 10 determined by the processing of the L1 signal may be used when processing the L5 signal after it is determined that the L1 signal is received along the LOS direction. For example, the phaser sequence generated by the motion compensation unit 20 when processing the received L1 signal further indicating the determined offset may be reused (using appropriate conversions) when generating the motion compensation correlation signal using the received L5 signal in step S116.

[0134] In the above, a GNSS positioning system has been described by focusing on a case where the first signal is a GPS L1 signal in the L1 band and the second signal is a GPS L5 signal in the L5 band. As described, this provides the advantage of reducing the processing load by performing initial processing on the L1 signal having a lower chipping rate than the L5 signal before committing processing resources to process the L5 signal. However, embodiments of the present invention may be directed to some different sets of the first and second signals, where it is advantageous to perform initial processing on the first signal before being able to reliably process the second signal to determine a metric of interest.

[0135] For example, the received first signal may be a low-bandwidth 5G signal in the FR1 band transmitted from a cell mast, and the second signal may be a high-bandwidth 5G signal in the FR2 band transmitted from the same mast. In yet a further example, the first signal may be a WiFi signal transmitted in the 2.4 GHz band, and the second signal may be a WiFi signal transmitted from the same access point in the 5 GHz band. Such WiFi signals may be used, for example, to perform indoor positioning.

[0136] In the above examples, the first and second signals are each in different frequency bands. However, this is not essential, and embodiments of the present invention may be used to process the first and second signals within the same frequency band. For example, the first and second signals can include civilian and military signals in the GPS L1 band. In another example, the first signal can have a larger signal-to-noise ratio than the second signal, making it possible to easily determine the sign phase and frequency parameters of the first signal for use in subsequent processing of the second signal, which is possible. In another example, the first signal can be encrypted, thereby making it possible to determine that the signals received from their respective remote sources are trustworthy by processing the first signal. The first and second signals are typically transmitted via their respective separate communication channels.

[0137] It is also assumed that the first and second signals may correspond to different signal types. For example, the first signal can be a Bluetooth signal, and at least one parameter obtained from the first signal is used to receive a second signal that is a WiFi signal from an access point located in the same location.

Claims

1. A method implemented in a wireless communication system, comprising: generating a first local signal; receiving, at a receiver, a first signal from a remote source; determining a movement of the receiver; generating a first correlation signal by correlating the first local signal with the received first signal; providing motion compensation for at least one of the first local signal, the received first signal, and the first correlation signal based on the determined movement of the receiver along a direction of interest, thereby generating a first motion-compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal is received along the direction of interest; after determining that the first signal is received along the direction of interest, generating a second local signal, the second local signal having at least one parameter based on the first signal received along the direction of interest; receiving, at the receiver, a second signal along the direction of interest; processing the received second signal using the second local signal to determine a metric of interest related to the receiver and / or related to a communication link including the receiver; A method comprising the above steps.

2. The method according to claim 1, wherein the first signal and the second signal have different signal characteristics.

3. The method according to claim 1 or 2, wherein the second signal is received from the remote source or from a second remote source co-located with the remote source.

4. The method according to any one of claims 1 to 3, wherein the second signal has a higher sampling rate than the first signal.

5. The method according to any one of claims 1 to 4, wherein the second signal has a higher bandwidth than the first signal.

6. The method according to any one of claims 1 to 5, wherein the first signal has a higher signal-to-noise ratio than the second signal.

7. The method according to any one of claims 1 to 6, wherein at least one of the first signal and the second signal is encrypted.

8. The method according to any one of claims 1 to 7, wherein the first signal is in a first frequency band and the second signal is in a second frequency band.

9. The method according to claim 8, wherein the first local signal corresponds to the first frequency band and the second local signal corresponds to the second frequency band.

10. The method according to any one of claims 1 to 9, wherein the direction of interest is a straight line direction between the receiver and the remote source.

11. Further comprising the step of determining at least one characteristic of the first signal received along the direction of interest, The method according to any one of claims 1 to 10, wherein the at least one parameter of the second local signal is based on the at least one characteristic of the first signal.

12. The at least one characteristic of the first signal is at least one of the sign phase and frequency of the first signal, The method according to claim 11, wherein the at least one parameter of the second local signal is at least one of the predicted sign phase or frequency of a second signal received along the direction of interest.

13. The method according to any one of claims 1 to 12, wherein the determination that the first signal is received along the direction of interest is based on a signal quality metric of the first motion compensation correlation signal.

14. Further comprising the step of generating one or more further first motion compensation correlation signals based on the determined motion of the receiver along one or more corresponding further directions, The method according to any one of claims 1 to 13, wherein the determination that the first signal is received along the direction of interest is based on the plurality of first motion compensation correlation signals.

15. The method according to any one of claims 1 to 14, further comprising the step of determining whether the received first signal includes a component received in a direction different from the direction of interest.

16. The step of processing the second signal comprises generating a second correlation signal by correlating the second local signal with the received second signal, Based on the determined movement of the receiver along the direction of interest, provide motion compensation for at least one of the second local signal, the received second signal, and the second correlation signal, thereby providing a priority gain for the second signal received along the direction of interest as compared to the components received in a direction other than the direction of interest, and generating a second motion-compensated correlation signal. The method according to any one of claims 1 to 15, comprising.

17. One or more parameters for providing the motion compensation during the generation of the second motion-compensated correlation signal are based on the corresponding one or more parameters for providing the motion compensation during the generation of the first motion-compensated correlation signal corresponding to the direction of interest. The method according to claim 16.

18. The step of providing motion compensation is Generating a series of phasors including a plurality of phasors indicating the phase and / or amplitude changes introduced into the received signal as a result of the determined movement of the receiver, each phasor including a phase angle and an amplitude. Combining the series of phasors with at least one of the local signal, the received signal, and the correlation signal. The method according to any one of claims 1 to 17, comprising.

19. Each of the first and second local signals is based on a local frequency or phase reference provided by a local oscillator, and the series of phasors further indicates an error in the frequency or phase reference provided by the local oscillator. The method according to claim 18.

20. The series of phasors used to generate the second motion-compensated correlation signal is based on the series of phasors used to provide the first motion-compensated correlation signal corresponding to the direction of interest. The method according to any one of claims 17 to 19.

21. A computer program product including executable instructions that, when executed by a processor in a wireless communication system, cause the processor to execute the method according to any one of claims 1 to 20.

22. A wireless communication system A receiver; A motion unit configured to determine the movement of the receiver; One or more processors; Comprising, The processor is Generating a first local signal; In a receiver, receiving a first signal from a remote source; determining the movement of the receiver; generating a first correlation signal by correlating the first local signal with the received first signal; providing motion compensation for at least one of the first local signal, the received first signal, and the first correlation signal based on the determined movement of the receiver along the direction of interest, thereby generating a first motion-compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal is received along the direction of interest; after determining that the first signal is received along the direction of interest, generating a second local signal, the second local signal having at least one parameter based on the first signal received along the direction of interest; in the receiver, receiving a second signal along the direction of interest; processing the received second signal using the second local signal to determine a metric of interest related to the receiver and / or related to a communication link including the receiver; A wireless communication system configured to perform.

23. The one or more processors are further configured to perform a step of determining at least one characteristic of the first signal received along the direction of interest, The system according to claim 22, wherein the at least one parameter of the second local signal is based on the at least one characteristic of the first signal.

24. The at least one characteristic of the first signal is at least one of the sign phase and frequency of the first signal, The system according to claim 23, wherein the at least one parameter of the second local signal is at least one of the expected sign phase or frequency of a second signal received along the direction of interest.

25. The system according to any one of claims 22 to 24, wherein the one or more processors are configured to determine whether the received first signal includes a component received in a direction different from the direction of interest.

26. The one or more processors are generating a second correlation signal by correlating the second local signal with the received second signal; providing motion compensation for at least one of the second local signal, the received second signal, and the second correlation signal based on the determined motion of the receiver along the direction of interest, thereby generating a second motion-compensated correlation signal to provide a priority gain for the second signal received along the direction of interest as compared to components received in a direction other than the direction of interest; The system according to any one of claims 22 to 25, further configured to perform. **Claim 27** The system according to any one of claims 22 to 26, further comprising an addressable storage device configured to store one or more parameters for providing motion compensation during the generation of the first motion-compensated correlation signal corresponding to the direction of interest. **Claim 28** The one or more processors are configured to generate a sequence of phasors including a plurality of phasors indicative of changes in phase and / or amplitude introduced into the received signal as a result of the determined motion of the receiver, each phasor including a phase angle and an amplitude, The system according to any one of claims 22 to 27, wherein the sequence of phasors is combined with at least one of the local signal, the received signal, and the correlation signal. **Claim 29** further comprising a local oscillator configured to provide a local frequency or phase reference, The system according to claim 28, wherein the sequence of phasors further indicates an error in the frequency or phase reference provided by the local oscillator. **Claim 30** The system according to any one of claims 22 to 29, wherein the receiver is configured to receive signals within two or more frequency bands. **Claim 31** The system according to any one of claims 22 to 30, wherein the one or more processors are configured to execute the method according to any one of claims 1 to 20. **Claim 32** The system according to any one of claims 22 to 31, wherein the system is provided on a single user device. **Claim 33** The method or system according to any one of claims 8 to 32, wherein the second frequency band is an L5 GNSS frequency band. **Claim 34** The method or system according to any one of claims 1 to 33, wherein the receiver is a GNSS receiver.

35. The method or system according to any one of claims 1 to 34, wherein the receiver is implemented on an electronic user device such as a smartphone.

36. The method or system according to any one of claims 1 to 35, wherein the wireless communication system is a positioning system, preferably a GNSS positioning system.

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