Wireless communication system and method

Abstract

A method performed in a wireless communication system is disclosed. The method comprises the steps of: generating a first local signal; receiving, at a receiver, a first signal from a remote source; determining 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 in the direction of interest to generate a first motion compensated correlation signal; determining, based on the first motion-compensated correlation signal, that the first signal has been received in the direction of interest; generating, after determining that the first signal has been received in the direction of interest, a second local signal having at least one parameter based on the first signal received in the direction of interest; receiving, at the receiver, a second signal in the direction of interest; and processing the received second signal using the second local signal to determine a measure of interest relating to the receiver, and / or relating to a communication link comprising the receiver. A wireless communication system is also disclosed.

Description

Technical Field

[0001] The present invention relates to wireless communication systems and methods. The present invention has particular application in positioning systems such as GNSS positioning systems. Background Art

[0002] Traditional GNSS receivers primarily use "L1" signals, which are signals transmitted in the L1 frequency band (center frequency 1.57542 GHz). Many modern civilian GNSS receivers are capable of receiving signals in the "L5" frequency band (center frequency 1.17645 GHz), and this band has become more popular recently as the number of satellites transmitting in this band has increased.

[0003] When used in GNSS applications for navigation and tracking, signals transmitted in the L5 band offer many advantages over L1 signals. The bandwidth of L5 signals is 10 times that of L1 signals (GPS L5 signals have a chip rate of 10.23Mcps, compared to 1.023Mcps for civil GPS L1 C / A signals), which can provide higher processing gain and improved positioning accuracy. L5 signals are also transmitted at greater power than L1 signals, and their lower frequency can improve reception in indoor applications.

[0004] However, the increased chip rate of the L5 signal means that a higher sampling rate is required at 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, requiring more processing power and battery resources. This is particularly problematic when the positioning system is implemented on a user device such as a modern smartphone, which has limited processing power and battery resources.

[0005] In addition, there remains the fundamental problem that the L5 signal is still subject to multipath effects, especially in challenging positioning environments where reflections are prevalent. Multipath effects refer to the situation where the signal from the satellite (or other remote source) takes an indirect non-straight line (NSL) trajectory from the satellite to the receiver - for example, due to one or more reflections from high-rise buildings in the so-called "urban canyon". Multipath effects cause two major problems. First, the reflected signal from the satellite can have a higher absolute power than the expected straight line (SL) signal, in which case the receiver can unexpectedly lock onto the NSL signal. Due to the additional path length of the NSL signal compared to the expected SL trajectory, the pseudorange is calculated incorrectly. Second, the NSL signal can interfere (e.g., constructively or destructively) with the SL signal at the receiver, adversely affecting the receiver's ability to accurately process the received signal. Even though the L5 signal provides improved processing, these problems still exist.

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

[0007] It would therefore be desirable to overcome these problems. Summary of the invention

[0008] According to a first aspect of the present invention, a method is provided for execution in a wireless communication system and includes the following steps: generating a first local signal; receiving a first signal from a remote source at a receiver; determining movement of the receiver; generating a first correlated 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 correlated signal based on the determined movement of the receiver along a direction of interest, thereby generating a first motion compensated correlated signal; determining that the first signal has been received along the direction of interest based on the first motion compensated correlated signal; after determining that the first signal has been received along the direction of interest, generating a second local signal having at least one parameter based on the first signal received along the direction of interest; receiving a second signal at the receiver along the direction of interest; and processing the received second signal using the second local signal to determine a measure of interest associated with the receiver and / or associated with a communication link including the receiver.

[0009] Thus, before dedicating resources to processing the second signal, embodiments of the present invention may be used to determine that the signal has been received along a direction of interest (typically a straight line or "line of sight" direction between the receiver and the remote source, as will be explained further below). Thus, after determining that the signal from the remote source is being received along the direction of interest, processing of the second signal may be performed with confidence (e.g., at least a component of the signal sent from the remote source is received at the receiver along the direction 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 that it has been received along the direction of interest before devoting resources to processing the second signal to determine the desired measure of interest. Examples of signal characteristics may include sampling rate, bandwidth, signal-to-noise ratio, and encryption properties. The first and second signals typically have substantially the same or similar propagation mechanisms and properties.

[0011] In one embodiment, the second signal has a greater sampling rate than the first signal. Typically, the second signal has a greater bandwidth than the first signal. For example, the second signal may have a greater chip rate than the first signal. Typically, the first signal has a longer coherence length (1 / bandwidth) than the second signal. Therefore, embodiments of the present invention are able to take advantage of the reduced processing requirements associated with the first signal so as to determine that the signal has been received along the direction of interest before devoting computing resources to 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 taking advantage of the enhanced signal characteristics of the second signal (e.g., greater sampling rate and / or bandwidth) when determining the attention metric. In an exemplary embodiment, the first signal may be a GPS L1 C / A signal, and the second signal may be a GPSL5 signal. However, in general, embodiments of the present invention may be applied to (e.g., radio) signals other than GNSS positioning signals. For example, embodiments of the present invention may be applied to WiFi, cellular, Bluetooth low energy (BLE) signals, etc., which present multiple frequency channels broadcast by the same remote source (or a co-located remote source). For example, the received first signal may be a low-bandwidth 3G signal transmitted from a cellular base station. Once it has been determined that 3G signals are received in the direction of interest, high bandwidth 4G signals received in the direction of interest may be processed with confidence.

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

[0013] In another embodiment, at least one of the received signals is encrypted. For example, the first signal may be an encrypted signal indicating that the remote source may be trusted. In such an example, the second signal is typically unencrypted.

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

[0015] In a typical embodiment, 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 band and the second signal may be a Wi-Fi signal in the 5 GHz band.

[0016] In embodiments where the first and second signals are located in respective first and third frequency bands, the receiver is typically configured to receive signals in more than one frequency band. Embodiments of the present invention may utilize a single receiver (e.g., the receiver is or includes a single receiver module) configured to receive signals in the first and second frequency bands. Such a receiver may be referred to as a "dual-band" or "multi-band" receiver. In alternative embodiments, the receiver may include (e.g., separately) first and second receiver modules configured to receive signals in the first and second frequency bands, respectively.

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

[0018] In a typical embodiment, the second signal will be 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 is worth noting that in practice, the first and second signals can be broadcast from dedicated antennas located on the same remote source, such as from separate antennas located on the same satellite or base station.) However, it is contemplated that the first and second signals can be transmitted from separate, substantially co-located remote sources, such as from respective positioning satellites in the same region of the sky, whereby the second signal is received along the direction of interest and therefore has 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 determining that the 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. Therefore, the second local signal has at least one parameter that has been determined during processing of the first signal. In this way, the computing resources required to process the second signal are greatly reduced compared to attempting to acquire and track the second signal without information obtained by processing the first signal within the first frequency band. By generating the second local signal in this manner, tracking of the second local signal can be continued directly. In some embodiments, until it has been determined that the first signal has been received along the direction of interest, the system may not perform any processing (e.g., no correlation) on the received second signal.

[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 an expected code phase or (eg Doppler) frequency of the second signal being received in the direction of interest. These parameters are determined based on properties of the received first signal.

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

[0023] These parameters can be used to track a second signal received along the direction of interest at a code 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 code phase and frequency space to acquire and subsequently track the second signal, thereby advantageously reducing the processing power required by the system and extending battery life. This is particularly beneficial in embodiments where the second signal requires a greater sampling rate than the first signal, as described above. Once the second signal is being processed, processing (e.g., tracking) of the first signal can be stopped, further enhancing processing and battery performance. If the second signal is lost, the method can be restarted based on processing of the first signal (e.g., alternately).

[0024] In embodiments where the first and second signals are within respective first and second frequency bands, it will be appreciated that the properties of the first signal need to be appropriately transformed 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 requires significantly reduced processing resources compared to processing the second signal without information that has been obtained during processing on the first frequency band. Such a transformation may be performed based on a known difference between the nominal (center) frequencies of the first and second frequency bands.

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

[0026] Typically, the determination of the movement of the receiver is performed based on measurements from which position and movement can be determined, 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 sensor can be part of an inertial measurement unit (IMU). Other examples of sensors that can be used to determine the movement of the receiver include magnetometers (typically configured to measure heading reference), pressure sensing devices such as barometers (typically configured to measure changes in altitude), LIDAR, RADAR, or camera- or visual odometry-based positioning systems. In some embodiments, the determination of the movement of the receiver can be assumed or predicted based on the previous movement of the receiver, as will be discussed herein.

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

[0028] Thus, the determination that the first signal has been received along the direction of interest (e.g., at least a component of the first signal is received along the direction of interest) is typically based on a signal quality metric of the first motion compensation related signal. The signal quality metric may be a signal-to-noise ratio of the first motion compensation related signal. The signal quality metric typically indicates the signal power received along the direction of applied motion compensation. When determining whether the first signal has been received along the direction of interest, the overall signal strength of the received signal may also be considered.

[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 arriving at the receiver from other directions (e.g., allowing for one or more reflections). Conversely, if the SNR is below the predetermined threshold (e.g., the SNR is ~1 or lower), this indicates that the first signal is not received along the direction of interest, particularly where the overall signal strength at the receiver is high. For GNSS signals, for a given system, an unobstructed LOS signal from a satellite to the ground can be expected to have a specific carrier-to-noise density (C / N0) (e.g., 40 dBHz), so the measured value of the 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 has been received along the direction of interest (e.g., without reflections).

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

[0031] Depending on the direction in which motion compensation is applied relative to the one or more directions in which the first signal is received, multiple first motion compensated related signals may have a relatively larger or smaller signal-to-noise ratio or C / N0 value. This information may be used to improve the reliability of the determination that the first signal is received along the direction of interest. In an embodiment, multiple motion compensated related signals may be generated substantially simultaneously (e.g., for the same epoch of the received signal). This may be achieved by providing multiple motion compensation processes for corresponding different directions substantially simultaneously. In this way, a single epoch of the received signal may be used to generate multiple different signal strength values ​​to reveal the energy arriving from the corresponding multiple 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 can be determined based on a plurality of motion compensation related signals indicating the relative strengths of signals from different directions, as described above. In some embodiments, such a determination can be based on a signal quality metric (e.g., a signal-to-noise ratio) of one or more first motion compensation related signals 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 related signal for the LOS direction may also display a smaller signal-to-noise ratio even if the total power of the received signal (e.g., the total power received at the antenna) is high. This would indicate the presence of a reflected component.

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

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

[0035] Once it is determined that a first signal from a remote source has been received along a direction of interest (typically a straight line between the receiver and the remote source), a second signal received along the direction of interest can be processed with confidence. This ensures that the positioning system does not waste processing or battery resources searching for or tracking a second signal when the second signal is not actually being received along the direction of interest. This allows the performance of the system to be improved (e.g., by processing the second signal to determine an interesting metric associated with the receiver, such as position or velocity, when it is known that the second signal has been received along the line of sight) while maximizing battery performance.

[0036] On the other hand, if it is determined that the first signal is not received in 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 previously described, in some embodiments, the second signal has a greater sampling rate (e.g., a greater chip rate) than the first received signal. It is further advantageous to use the first signal in order to determine whether a signal has been received in the direction of interest because the reduced sampling rate results in a wider coverage of the search space within the correlation period. For example, where the first signal is a GPS L1 C / A signal and the second signal is a GPS L5 signal, the lead, prompt, and lag code (half a chip apart) correlations for the L1 signal may cover a search space of approximately 100 meters, while the search for the L5 signal will cover a search space of approximately 10 meters. Therefore, the L1 (e.g., bandwidth reduced) signal is advantageous in determining whether a signal from a particular remote source has been received in the direction of interest.

[0038] The method includes processing the received second signal using the second local signal to determine an interest metric associated with the receiver and / or associated with 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 interest metric.

[0039] The receiver-related interestingness metric may be the receiver's position, velocity, time, or direction of motion (e.g., a "physical" metric related to the receiver). The receiver-related interestingness metric is typically used to determine a tracking or navigation solution for the receiver. In such an embodiment, the wireless communication system is typically a positioning system or a portion thereof.

[0040] Therefore, in a preferred embodiment, the present invention provides a method performed in a positioning system and comprising the following steps:

[0041] generating a first local signal;

[0042] receiving, at a receiver, a first signal from a remote source (e.g., where the first signal is a GPS L1 C / A signal);

[0043] determining movement of the receiver;

[0044] generating a first correlated signal by correlating the first local signal with the received first signal;

[0045] providing motion compensation for at least one of the first local signal, the first received 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;

[0046] determining, based on the first motion-compensated correlation signal, that the first signal has been received along a direction of interest;

[0047] After determining that the first signal has been received along the direction of interest, generating a second local signal having at least one parameter based on the first signal received along the direction of interest;

[0048] receiving, at the receiver, a second signal along the direction of interest (eg, where the second signal is a GPS L5 signal); and

[0049] The received second signal is processed using the second local signal to determine an attention metric associated with the receiver (eg, where the attention metric is at least one of a position, velocity, time, or direction of motion of the receiver).

[0050] The second signal may be processed (using the second local signal) to determine an interest metric associated with a communication link including the receiver. The communication link may be a cellular telecommunications link (e.g., a 3G, 4G, or 5G communication link), or, for example, a Wi-Fi or Bluetooth data communication link. Examples of interest metrics associated with the communication link and that may be determined by processing the second signal include channel estimation parameters (e.g., channel state information), frequency selection, quality of service, signal availability, and quality of a communication channel between the receiver and a remote source.

[0051] In some embodiments, the processing of the second signal includes: generating a second correlated signal by correlating the second local signal with the received second signal; and providing motion compensation of at least one of the second local signal, the received second signal, and the second correlated signal based on the determined movement of the receiver along the direction of interest, thereby generating a second motion compensated correlated signal (e.g., providing a preferential gain for the second signal received along the direction of interest compared to components received in directions other than the direction of interest). In such embodiments, the generation of the second motion compensated correlated signal occurs during a second time period that is later than the first time period for generating the first motion compensated correlated signal.

[0052] By performing motion compensation based on the determined movement of the receiver along the direction of interest, the methods of various embodiments can advantageously provide preferential gain for a second signal received along the direction of interest. The signal in the direction of interest (e.g., a LOS signal) can achieve the highest correlation even if the absolute power of the signal in the direction of interest (e.g., a LOS signal) is less than the absolute power of a signal not received along the direction of interest (e.g., a non-LOS signal). The use of motion compensation can also advantageously increase the coherent integration period of the received signal, thereby enhancing the system's ability to detect very weak signals, such as GNSS signals received indoors or LOS signals passing through a building. In order to effectively detect weak signals, an integration time of approximately 1 second or longer may be required in some arrangements.

[0053] Therefore, performing motion compensation for the received second signal can advantageously further improve the accuracy of a metric of interest associated with the receiver and / or the communication link determined using the second signal, for example by reducing multipath effects. Such an embodiment is particularly advantageous if processing of the first signal has determined that the received first signal includes components in a direction different from the direction of interest (e.g., a reflected signal that is not a LOS), and / or if the received signal along the direction of interest is weak (e.g., attenuation caused by a building). On the other hand, if it is determined that the first received signal does not include any reflected components (e.g., the receiver is in a "clear sky" environment), motion compensation for the second frequency band may not be performed, thereby saving battery energy.

[0054] As further discussed herein, providing motion compensation advantageously compensates for phase and / or amplitude changes in the received signal due to the motion of the receiver. As discussed, motion compensation can be provided to at least one of the local signal, the received signal, and the related signal to generate a motion compensated related signal. Motion compensation can be provided to the local signal before correlation so that it matches the received signal more closely. In another arrangement, motion compensation can be applied to the received signal to reduce the impact of the motion of the receiver on the received signal. Similar results can be achieved by providing partial motion compensation for the local signal and the received signal. These techniques allow relative motion compensation to be applied between the local signal and the received signal. In some embodiments, motion compensation can be performed in parallel with correlation. Motion compensation can also be applied directly to the related signal.

[0055] In practice, the received signal may be processed as a complex signal comprising in-phase and quadrature components. The local signal may be a similarly complex signal. The correlation signal may also be a complex signal and may be used as a measure of the correlation between these complex signals.

[0056] High positioning accuracy can be achieved by providing motion compensation of at least one of the local signal and the received signal based on the movement in the determined direction of interest. In practice, the local and received signals can be encoded with a periodically repeated code. In the case of GNSS signals, for example, for GPS L1C / A code, the local and received signals can include 1023 pseudo-random digital chips. The local and received signals can be analog waveforms, which can be digitized to provide values ​​at the radio sampling rate, which means that millions of values ​​can exist in a time period of 1ms. The correlation between the local signal digital value and the received signal digital value can be calculated to first correct any set of values ​​in the relevant time period using the motion compensation phasor (described in this article). Then, these data points can be summed over the time period. In practice, this can produce accurate results because it works at the radio sampling frequency, although it may require a lot of calculations.

[0057] The motion compensated correlation signal can be generated by providing motion compensation to the correlation signal. In such a case, one or more code words (1 ms long and containing 1023 chips in the case of GPS L1 C / A code) are usually used to obtain the correlation result, and the obtained correlation result is motion compensated.

[0058] In another example, correlation can be performed independently on each of the ~1000 pseudo-random digital chips to produce ~1000 complex correlator signal outputs. Then, motion compensation can be applied to these ~1000 correlated signal components. Finally, these signal outputs can be summed to produce a correlated measure. This method can provide an approximation of the results that can be achieved by motion compensation of the local signal and the received signal. However, for some applications, the loss of accuracy can be ignored and can be accepted because it can reduce the computational load.

[0059] As described above, in embodiments of the present invention, motion compensation is performed to obtain motion compensated related signals of a received first signal (e.g., determining LOS and non-LOS directions) and a received second signal (e.g., 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 related signal is based on the motion compensation provided during the generation of the first motion compensated related signal corresponding to the direction of interest. Typically, one or more parameters used to provide motion compensation during the generation of the second motion compensated related signal are based on the corresponding one or more parameters used to provide motion compensation during the generation of the first motion compensated related signal corresponding to the direction of interest.

[0060] In other words, one or more motion compensation parameters for generating a first motion compensation related signal corresponding to the direction of interest based on the determined movement of the receiver can be reused or form the basis for motion compensation parameters for generating a second motion compensation related signal. This advantageously reduces the computational load when performing motion compensation to generate the second motion compensation related signal. Such parameters may include a motion compensation phasor sequence as described below. If the motion of the receiver is determined to be substantially the same (e.g., within a predetermined threshold) during the first and second time periods for generating the corresponding motion compensation related signal, one or more motion compensation parameters can be reused. Otherwise, the motion compensation parameters are recalculated during the second time period to generate the second motion compensation related signal.

[0061] In general, providing motion compensation (e.g., when generating a first or second motion-compensated related signal) includes generating a phasor sequence including a plurality of phasors indicating phase and / or amplitude changes (e.g., over time) introduced into the received signal due to a determined motion of the receiver (e.g., in a corresponding direction), each phasor including a phase angle and an amplitude, and combining (e.g., mixing) the phasor sequence with at least one of the local signal, the received signal, and the related signal. Thus, the phasors may be described as indicating a determined movement of the receiver (e.g., in a corresponding direction).

[0062] Typically, the phasor sequence is derived from the determined movement of the receiver over time. For example, each phasor in the phasor sequence may indicate the movement of the determined receiver within a specific time interval. Therefore, the resulting phasor sequence indicates (e.g., corresponds to) the movement of the determined receiver within a time period consisting of the individual time intervals. The movement of the receiver can be determined by measurements of the receiver's movement (e.g., using one or more measurements of a gyroscope, magnetometer, accelerometer, speed, step count, etc.), or by assuming the receiver's movement based on past movements (e.g., constant movement in a specific direction due to vehicle travel or repeated movement due to pedestrian travel). In addition, the movement can be extrapolated or calculated based on previous movements in a specific environment. In such a case, machine learning techniques can be used to predict the movement of the receiver. The phasor sequence can reflect the detailed movement of the receiver over time. For example, multiple phasors within the phasor sequence can reflect the movement of the receiver while it is resting in the user's pocket while jogging, walking, running, or performing some other repetitive movements. In this example, the receiver can perform a cyclic movement with an acceleration peak corresponding to each heel strike. If motion measurements are unavailable or inaccurate, motion may be assumed (eg, "predicted") from such repetitive motion.

[0063] Typically, both the first and second local signals are based on a local frequency or phase reference provided by a local oscillator (such as a quartz crystal).In some embodiments, motion compensation (eg, when generating the first or second motion-compensated related signals) may include correcting errors in the frequency or phase reference.

[0064] In some embodiments, the first and second local signals are both based on a local frequency or phase reference provided by a local oscillator, and wherein the phasor sequence further indicates an error in the frequency or phase reference provided by the local oscillator. The error in the local oscillator can be determined by an offset between the local frequency or phase reference and a received frequency or received phase of a reference signal received from an oscillator reference source, the reference signal having a known or predictable frequency or phase; and wherein the phasor sequence indicates the determined offset (e.g., as a function of time). The phase angle and / or amplitude of the phasor sequence can be adjusted based on the determined offset (or time series of offsets). Such embodiments advantageously facilitate elimination of errors introduced into the associated signals by instabilities in a local oscillator of the positioning system. This is particularly advantageous in embodiments where the local oscillator is simple and low cost, such as a quartz crystal (e.g., for consumer devices such as smartphones).

[0065] In another example, the error in the frequency or phase reference provided by the local oscillator can be determined by using multiple phasor sequences (e.g., for each particular direction of interest) that indicate a corresponding multiple different predictions or "hypotheses" of the local oscillator error. The multiple phasor sequences can indicate corresponding predictions of the rate of change of the frequency and / or frequency offset of the local oscillator. In this way, multiple motion compensated correlation signals can be generated, where the motion compensated correlation signal exhibits the highest power corresponding to the error of the local oscillator.

[0066] In an embodiment, the error in the frequency or phase reference provided by the local oscillator is determined by processing the received first signal. For example, different assumptions about the local oscillator error may be used when generating the first motion compensated related signal or an offset determined for 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.

[0067] In various embodiments, the phasor sequence used to generate the second motion compensation related signal is based on the phasor sequence used to provide the first motion compensation related signal corresponding to the direction of interest. For example, one or more phasor sequences used to generate the first motion compensation related signal along the direction of interest (e.g., LOS) can be stored in an addressable memory and accessed when generating the second motion compensation related signal. This "reuse" of the phasor sequence advantageously reduces the processing resources required to generate the second motion compensation related signal. During the processing of the first and second signals, if the motion of the receiver is substantially the same, the motion compensation phasor sequence can be reused. In embodiments where the first and second signals are in different frequency bands, it should be understood that due to the different frequency bands of the first and second signals, one or more phasor sequences will need to have the applied transformation (e.g., offset) when used in association with the second motion compensation related signal. However, compared to regenerating one or more entire phasor sequences, the processing power required to apply such a transformation is negligible.

[0068] In this way, by basing the phasor sequence used to generate the second motion compensated related signal on the phasor sequence used to provide the first motion compensated related signal, information determined during processing of the first signal (e.g., errors in a frequency or phase reference provided by a local oscillator) can be advantageously used to process the received second signal, thereby reducing the computational load.

[0069] As another advantage provided by embodiments of the present invention, an advantage of generating a second local signal having at least one parameter based on a first signal received in a direction of interest is that second signals (e.g., in a second frequency band) can be tracked that may be too weak to be directly acquired, either due to the environment (e.g., a LOS second signal may pass through a building between the remote source and the receiver) or due to the receiver's antenna (e.g., the antenna does not have sufficient gain). In other words, the directional information obtained from the analysis of the first signal about where to track the second signal means that a second signal that would not otherwise be acquired can be tracked. Using motion compensation (in the analysis of the first signal and optionally in the subsequent processing of the second signal) to enhance the gain of the second signal received in the direction of interest advantageously means that an antenna that is not specifically designed for such a signal can be used to detect and track the second signal. This advantageously means that lower quality or cheaper antennas can be used, or that existing antennas (e.g., cellular antennas) within the system can be "reused." Thus, the number of antennas in 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).

[0070] For example, where the first signal is a GPS L1 C / A signal and the second signal is a GPS L5 signal and (e.g., a positioning system) is implemented in a smartphone, due to the enhanced gain and sensitivity provided by the present invention, the cellular antenna can be "reused" to track the L5 signal without the need for a separate L5 antenna.

[0071] According to a second aspect of the present invention, there is provided a computer program product comprising executable instructions, which, when executed by a processor in a wireless communication system, cause the processor to perform the steps of any embodiment of the above first aspect.

[0072] Disclosed herein is a non-transitory computer-readable medium comprising executable instructions, which, when executed by a processor in a wireless communication system, cause the processor to perform the steps of any embodiment of the first aspect described above.

[0073] Further disclosed herein is a wireless communication system, comprising: a receiver (eg, configured to receive a signal from a remote source); and one or more processors configured to perform the method described in any of the above examples.

[0074] According to a third aspect of the present invention, a wireless communication system is provided, comprising: a receiver (e.g., configured to receive a signal from a remote source); a motion unit configured to determine the movement of the receiver; and one or more processors configured to perform the following steps: generating a first local signal; receiving a first signal from a remote source at the receiver; 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 that the first signal has been received along the direction of interest based on the first motion compensated correlation signal; after determining that the first signal has been received along the direction of interest, generating a second local signal having at least one parameter based on the first signal received along the direction of interest; receiving a second signal at the receiver along the direction of interest; and processing the received second signal using the second local signal to determine a measure of interest associated with the receiver and / or associated with a communication link including the receiver.

[0075] Therefore, the system of the third aspect provides all the advantages described above.In general, one or more processors may be configured to perform any of the method steps described above.

[0076] The one or more processors are also typically configured to perform the step of determining at least one property of a first signal received along the direction of interest, and wherein the at least one parameter of the second local signal is based on at least one characteristic of the first signal. Typically, as described above, the at least one property of the first signal is at least one (preferably both) of a code phase and a frequency of the first signal, and wherein the at least one parameter of the second local signal is at least one (preferably both) of an expected code phase or frequency of a second signal being received along the direction of interest (e.g., within a second frequency band).

[0077] In various embodiments, 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.

[0078] In various embodiments, one or more processors are further configured to perform the following steps: generating a second correlated signal by correlating the second local signal with the received second signal; and providing motion compensation for at least one of the second local signal, the received second signal, and the second correlated signal based on the determined movement of the receiver along the direction of interest, thereby generating a second motion compensated correlated signal (for example, providing priority gain for the second signal received along the direction of interest compared to components received in directions other than the direction of interest).

[0079] In various embodiments, the system further comprises an addressable memory configured to store one or more parameters for providing motion compensation during the generation of the first motion compensation-related signal corresponding to the direction of interest. Such one or more parameters may be reused (e.g., by appropriate transformation) when generating the second motion compensation-related signal using the received second signal, thereby advantageously reducing battery resources.

[0080] Typically, one or more processors are configured to generate a phasor sequence comprising a plurality of phasors indicative of phase and / or amplitude changes introduced into a received signal due to determined motion of the receiver, each phasor comprising a phase angle and an amplitude, wherein the phasor sequence is combined with at least one of a local signal, a received signal, and a correlated signal.

[0081] Typically, the system also includes a local oscillator configured to provide a local frequency or phase reference (e.g., for generating the first and second local signals). In an embodiment, the phasor sequence also indicates an error in the frequency or phase reference provided by the local oscillator. In this way, as described above, the mobile receiver can provide a longer coherent integration of the signal than would otherwise be possible.

[0082] Typically, a receiver is configured to receive signals in more than one frequency band.

[0083] The wireless communication system as described herein is typically a positioning system, preferably a GNSS positioning system. In an embodiment, the system may be a communication system, such as a cellular communication system, or a Wi-Fi or Bluetooth communication system.

[0084] The system is typically provided on a single user device, such as an electronic user device such as a positioning device or a smartphone. Alternatively, the various units in the system may be provided separately so that the system is distributed (i.e. configured as a distributed system). For example, certain computations may be performed by processors in the network. Therefore, in order to improve efficiency, the electronic user device may offload computations to other processors in the network where appropriate.

[0085] The one or more remote sources from which the signal is received are typically trusted remote sources (such as GNSS positioning satellites) from which the data received can be trusted, i.e., assumed to be correct. The received signal may include any known or unknown transmission information pattern (whether digital or analog) that can be found in the broadcast signal by a cross-correlation process using a local copy of the same pattern. The received signal may be encoded with a code chip that can be used for ranging. Examples of such received signals include GPS signals, which include gold codes encoded in radio transmissions. Another example is an extended training sequence used in GSM cellular transmissions. In another 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.

[0086] In various embodiments of the 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.

[0087] In any aspect of the 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 invention may also be applied to other (e.g. radio) signals such as cellular, DAB or DVB, Wi-Fi or Bluetooth signals received from a corresponding remote source.

[0088] In embodiments, the determined interest metric associated with the receiver and / or with a communication link including the receiver may include one or more of the following: the location of the receiver, the velocity of the receiver, the direction of motion of the receiver, the time at the receiver, a tracking or navigation solution of the receiver, one or more channel estimation parameters, channel frequency selection parameters, a quality of service metric, a signal availability metric, a quality metric of a communication channel between the receiver and a remote source. As has been described, embodiments of the present invention may also be used to enhance reception of signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Example embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0090] Figure 1 is a schematic diagram illustrating an example environment in which the positioning system and method of the present invention may be used;

[0091] Figure 2 is a schematic diagram showing relevant components of a positioning system according to an embodiment of the present invention;

[0092] Figure 3 is a flow chart illustrating the steps of a method according to an embodiment of the present invention;

[0093] Figure 4 is a schematic diagram showing how to generate a motion compensation related signal according to an embodiment of the present invention;

[0094] Figure 5 is a schematic diagram showing how to generate a motion compensation related signal according to an embodiment of the present invention; and

[0095] Figure 6 is a schematic diagram showing how to generate a motion compensation related signal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0096] The following description will focus on embodiments of the invention implemented in a positioning system, where the processed signals are GNSS positioning signals, e.g., to determine position, velocity, and / or time relative to a receiver. However, the techniques taught herein may be applied to other wireless communication systems for processing other (e.g., radio) signals, such as cellular, WiFi, etc., to determine other interesting metrics discussed herein.

[0097] Figure 11 is a schematic diagram showing by way of example an environment in which the positioning device 1000 is positioned within an "urban canyon" environment, the environment being located between high-rise buildings 50a, 50b, and radio signals including GNSS signals from a remote source may be reflected by the high-rise buildings. Due to reflection and multipath effects, such an "urban canyon" environment is typically a challenging environment for a positioning system to accurately determine a positioning solution.

[0098] exist Figure 1 In the example of , the positioning device 1000 receives signals from GNSS positioning satellites 200a, 200b, which in this example are part of the Global Positioning System (GPS) constellation. However, it should 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 between the device and the satellite, which direction may be referred to as a "line of sight" (LOS) direction. The signal from the first satellite 200a also includes a reflected component D2, which reaches the positioning device after being reflected from the surface of the building 50a. The positioning device also receives an L1 signal from a second satellite 200b, which includes a strong reflected component D4. However, as Figure 1 As shown, since the component is blocked by the building 50b, no signal from the second satellite 200b is received at the positioning device 1000 along the LOS direction D3.

[0099] Positioning satellites 200a, 200b also transmit signals in the GPS L5 frequency band, and it is desirable to receive and process these signals in order to enhance navigation and tracking solutions by taking advantage of the properties of L5 signals compared to GPS L1 signals. The path of L5 signals between the satellites and positioning device 1000 is the same as the path of L1 signals described above. Figure 1 Some of the challenges faced by positioning systems when attempting to determine a navigation or tracking solution in a challenging environment, such as the urban canyon shown, are shown. The LOS and reflected components of the broadcast signal from satellite 200a arrive at the positioning device via different paths shown by D1 and D2, and are therefore received at different times and may have different attenuation and phase characteristics. Therefore, the LOS and reflected components of the signal received from satellite 200a may act as noise that is correlated to each other (e.g., by constructive and / or destructive interference), thereby causing significant problems in positioning accuracy.

[0100] In addition, the signal from satellite 200b is received at positioning device 1000 only after reflection (because the LOS direction is blocked by building 50b). A conventional multi-band system can determine that the L1 signal from satellite 200b is received at a power above a predetermined threshold and can therefore confidently continue to process the L5 signal from satellite 200b in order to take advantage of the improved processing and positioning accuracy provided by such a signal. However, due to the reflective nature of the received signal, the navigation and tracking solutions generated using the L5 signal will still be erroneous, even though the tracking and navigation solutions can be reported with confidence.

[0101] Embodiments of the present invention seek to overcome these problems.

[0102] Figure 2 Schematic diagram showing relevant components of a positioning system according to an embodiment of the present invention (eg, Figure 1 , implemented on a single positioning device 1000). The receiver schematically shown at 100 includes or is coupled to an antenna 2, which is configured to receive radio frequency signals, such as the GNSS signals described above. In particular, the antenna 2 is configured to receive radio frequency signals in two or more separate radio frequency bands (although it is conceivable that the receiver may include or be coupled to separate dedicated antennas for the respective bands). In this embodiment, the antenna is capable of receiving signals in the L1 band (1.57542 GHz) and the L5 band (1.17645 GHz). Typically, the broadcast signal received at the antenna 2 is an analog signal and is amplified, down-converted to baseband or lower frequency, and converted to digital form by an analog-to-digital converter. These processes typically occur 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).

[0103] like Figure 2 As shown, 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 in the L1 frequency band (e.g., signals from different satellites), and a plurality of channels configured to process signals received in the L5 frequency band, such as Figure 2 The following description will relate to the processing of signals on the L1 channel, although the corresponding description applies to the processing performed in the L5 channel.

[0104] The received L1 signal is correlated in a correlation unit 12-1 with a local copy of the 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 of a GNSS satellite) using a frequency or phase reference of a local oscillator 10. The local signal generator is typically a frequency synthesizer. The local oscillator 10 is typically simple and low cost, particularly when the positioning device is implemented on a handheld electronic device (such as a smartphone). For example, the local oscillator 10 may comprise a quartz crystal.

[0105] 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 may include inertial sensors, such as accelerometers and gyroscope sensors, from which data can be used to infer the motion of the receiver. The motion unit 4 typically includes an inertial measurement unit (IMU) using inertial sensors, although other (non-GNSS) devices that determine the motion of the receiver, such as barometers, magnetometers, and visual odometer systems, 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.

[0106] The motion compensation unit 20 derives a motion compensation phasor indicating amplitude and / or phase changes 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 at a subsequent time period.

[0107] After acquisition, the updated estimates of the code phase and frequency of the received signal can be fed back to the local signal generator 8-1 to track the received signal. As known in the art, such a "tracking loop" can be a delay locked loop (DLL) for tracking the code phase of the input signal, and a phase locked loop (PLL) or frequency locked loop (FPP) for tracking the carrier.

[0108] The signal analysis unit 14 analyzes the motion compensated related outputs of the channels in order to provide a navigation or tracking solution, as will be described in further detail herein.

[0109] Each of the above-mentioned units of the positioning system is in logical communication with a processor 1 that is operable to control the operation of the respective unit according to the software or firmware executed. In the presently shown embodiment, the units (or "modules") are provided within a single positioning device 1000. It should be understood that the arrangement of the various units shown is merely exemplary, and that the units may be arranged according to the device in which the system is implemented, if desired. In an alternative embodiment, the various units of the system may be provided in a distributed manner across a network.

[0110] Figure 3 is a flowchart outlining the main steps of an embodiment of the present invention, and will refer to Figure 1 and Figure 2 At step S100, the receiver 100 receives a GPS L1 signal from a satellite (eg, positioning satellite 200a). As described above, the signal received at the receiver includes components traveling along a straight line between the receiver and the satellite and a non-straight line direction of reflection. Figure 3 The following description will be primarily based on processing positioning signals received from satellite 200a, but it will be appreciated that the steps of the flowchart may be performed for any remote source (or co-located remote source) from which signals in two frequency bands may be received.

[0111] At step S102, the motion unit 4 determines the motion of the receiver 100. The motion unit 4 can measure the motion of the receiver using data obtained from an inertial sensor as part of the IMU, such as by integrating acceleration measurements from an accelerometer to infer the speed of the receiver. The motion module can assume ("predict") the motion of the receiver based on the movement pattern of the previous epoch. For example, if the previous measurement indicates that the receiver 100 is moving in a constant direction and at a constant speed, it can be assumed that the current motion is the same as the motion in the previous time period. This is particularly true for contexts where the motion may remain substantially similar, such as if the receiver is located in a moving vehicle or held by a jogger. By assuming the motion of the receiver within an appropriate time period, the processing load can be reduced and battery resources can be saved. The motion unit 4 can calculate the motion based on historical motion at a specific time of the day, or machine learning (e.g., a recursive neural network) can be used to predict motion from historical motion data.

[0112] At step S104, the motion compensation unit 20 receives the determined motion of the receiver from the motion unit 4 and generates a phasor sequence based on the motion of the receiver in the line of sight (straight line) direction D1 between the receiver and the satellite 200a. (Note that in this example, the direction of interest is the line of sight (LOS) direction, although as previously described, the direction of interest may be a direction other than line of sight). Thus, returning to reference Figure 1, with respect to the signals received from satellite 200a, the motion compensation unit 20 is configured to construct a phasor sequence indicating the motion of the receiver along the LOS direction D1. Similarly, when processing the signals from satellite 200b, the motion compensation unit 20 is configured to construct a phasor sequence indicating the motion of the receiver along the LOS direction D3. These straight-line directions can be known or estimated based on an initial estimate of the receiver position and from broadcast orbit data or ephemeris from a satellite constellation. An initial estimate of the receiver's position can be determined using conventional GNSS ranging calculations based on available signals. If available, an initial estimate of the position can also be determined based on cellular data (for example, in the case where the system is provided in a smartphone). Typically, depending on the environment of the receiver, an initial estimate of the position can be determined using conventional techniques within an accuracy of better than 20 meters.

[0113] Each phasor sequence φ comprises a plurality of phasors, wherein each phasor generally has the same duration as a sample of the received signal. i The number N of (i=1..N) is usually the same as the samples of the received signal and the samples of the local signal during the period of time when the received signal and the receiver movement are measured. Each phasor φ i represents a phase and amplitude compensation based on the motion of the receiver at time t (e.g., each phasor contains a phase angle and an amplitude), such that a phasor sequence consisting of a plurality of phasors indicates the motion of the receiver as a function of time in a particular direction. In this way, each phasor sequence indicates a phase and / or amplitude change introduced into the received signal as a result of the motion of the receiver. For example, the velocity of the receiver derived from the motion unit 4 can be used to determine the Doppler shift introduced into the received signal due to the motion of the receiver in the line of sight direction. The Doppler shift can then be integrated over time to estimate the phase value.

[0114] Therefore, the phasor sequence may be referred to as a "motion compensated" phasor sequence.

[0115] Phase φ i is a transformation in phase space and is a complex value, which generates the in-phase component of the motion-compensated phasor sequence via its real value and generates the quadrature-phase component of the motion-compensated phasor sequence via its mirror value. i It is typically a circulating phasor and can be represented in a number of different ways, for example as a clockwise rotation from the real axis or a counterclockwise rotation from the imaginary axis.As described above, the sequence of phasors for each direction indicates the determined movement of the receiver in that direction.

[0116] Each phasor sequence may be stored in the storage unit 17 (step S104a) and reused in an appropriate subsequent time period, wherein the determined motion of the receiver remains substantially constant across the time period.

[0117] Return to reference Figure 3 In step S106, a motion compensated correlation signal is generated for the received L1 signal along the LOS direction D1 between the receiver and the 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, wherein motion compensation is applied to at least one of the local signal, the received signal and the resulting correlation signal based on the determined movement of the receiver along the LOS direction D1 determined by the motion unit 4. This is performed by combining the phasor sequence derived by the motion compensation unit 20 at step S104 with at least one of the received signal, the local signal and the correlation signal.

[0118] Each phasor sequence φ may be applied to at least one of a local signal, a received signal, or a correlation result (eg, an initial correlation signal). Figure 4 is a schematic diagram showing how the phasor sequence calculated by the motion compensation unit 20 is 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 phasor generation unit 20 to generate a phasor 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 phasor sequence generated by the motion compensation unit 20-1 to generate a motion compensated local signal, such as Figure 4 The motion compensated local signal L-MC is then correlated with the received signal R at a correlation unit 12 (e.g. after initial processing at the receiver) to provide a motion compensated correlated signal, as shown by C-MC. The motion compensated correlated signal is then passed to a signal analysis unit 14. In practice, the in-phase and quadrature-phase components of the phasor sequence φ will be combined with the local signal to produce the in-phase and quadrature-phase motion compensated local signals for correlation.

[0119] As already explained herein, generally a phasor sequence φ may be applied to at least one of the local signal, the received signal and the correlation signal generated by the correlator to perform motion compensation. Figure 5 It is schematically shown that a received signal R is provided with motion compensation (generating a motion compensated received signal R-MC for correlation with a local signal L), thereby generating a motion compensated correlation signal C-MC. Figure 6 Schematically shown is the process of applying motion compensation to a correlation signal (C), which is generated by correlating a (non-motion compensated) received signal with a local signal in order to generate a motion compensated correlation signal C-MC which can be passed to the signal analysis unit 14 .

[0120] The number of correction phasors in the phasor sequence φ corresponds to the number of signal samples to which motion compensation is being applied (e.g., within the time period of the coherent integration). For example, both the received signal and the local signal will typically be sampled at the same rate, and therefore have the same number of samples per second (e.g., 4 million samples per second). Thus, for example, the same phasor sequence φ can be applied to either the local signal or the received signal in order to generate the same motion compensated correlated signal. When motion compensation is applied to the correlated signal after correlation of the ("raw") local and received signals, the phasor sequence φ will typically have fewer elements than when applied to either the local or received signal due to the typically lower sampling rate of the correlated signal (e.g., about 1000 samples per second).

[0121] Further details on the generation of motion compensated phasor sequences and their use in generating motion compensated related signals can be found in commonly assigned patent publication number WO2017 / 163042, the entire contents of which are incorporated herein by reference.

[0122] This process produces a motion compensated correlation signal whose signal-to-noise ratio (SNR) can be calculated. This SNR can be used to determine whether the L1 signal has been 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, it can be inferred that the receiver 100 is receiving the signal along the LOS direction between the receiver and the remote source. Return to Reference Figure 1 , when analyzing the signal received from satellite 200a, although receiver 100 receives the LOS (D1) and reflection (D2) components of the broadcast signal, the SNR of the motion-compensated correlation signal along the LOS direction is greater than a predetermined threshold, indicating that the signal component is indeed received along the LOS. In contrast, for satellite 200b, although the overall signal strength received from satellite 200b will be relatively high due to reflection component D4, the SNR of the motion-compensated correlation signal along the LOS direction D3 is lower than a predetermined threshold, indicating that the receiver does not receive the LOS component (in this case blocked by building 50b).

[0123] Thus, by performing motion compensation in this manner, it is possible to determine whether a signal is received along the LOS direction between the receiver and the corresponding satellite (step S108). The directionality provided by the motion compensation process advantageously allows an energy search to be performed along the LOS direction, thereby improving the accuracy of the determination.

[0124] Optionally, at step S109, motion compensated related signals may be generated for other directions in addition to the above-mentioned LOS direction. This can be advantageously used to determine the signal environment of the receiver, for example to determine whether there is a reflected signal. The signal analysis unit is configured to determine one or more candidate directions along which the reflected signal can be received. By generating a motion compensated phasor sequence indicating the motion of the receiver along these candidate directions and then generating motion compensated related signals corresponding to these directions, it can be determined whether the reflected signal is indeed received along the candidate direction. Although not required, a 3D terrain model (e.g., a 3D city model) of the receiver's environment can be used to determine the candidate directions based on the receiver's initial estimate of the position and the fact that it has been established. Such a 3D model can be stored on the storage device 17 or retrieved via the Internet or other data connection.

[0125] continue Figure 1 In the example environment shown, the established fact about satellite 200a is that a LOS signal exists because the SNR of the motion-compensated 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 can be used to determine candidate directions along which reflected signals may be received at the receiver, such as Figure 1 The direction reflected by the building 50a is shown. If a motion compensated correlation signal is generated about the candidate direction D2, it will have a high SNR since the candidate direction corresponds to the actual reflection direction. This indicates that the signal received from the satellite 200a does include a reflection component.

[0126] Similarly, it is an established fact about satellite 200b that the signal is unlikely to be received in the LOS direction (due to the low SNR of the motion compensated correlation signal in that direction), but the total signal strength received at the receiver is high. This strongly indicates the presence of a reflected component received at the receiver. Again, the 3D model can be used to determine one or more candidate directions in which additional motion compensation is to be performed and motion compensated correlation signals generated. In this case, the motion compensated correlation signal corresponding to direction D4 will return a very high SNR, which is highly indicative of the presence of a reflected component.

[0127] In some embodiments, the system will not have access to a 3D model. In such embodiments, the signal analysis unit 14 may determine candidate directions based on a "brute force" search of the sky. Multiple candidate directions (e.g., each direction defined by an azimuth and an elevation) 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 may be analyzed to infer the likelihood of receiving a reflected signal along that direction.

[0128] Such a "brute force" search of the sky is computationally intensive, so a comprehensive scan of the signals received at the receiver is required, preferably using a 3D model.

[0129] Thus, the method may include using multiple motion compensated correlation signals to measure the power of signals arriving from different directions. Multiple motion compensated correlation signals (and thus subsequently the angle of arrival) may be generated substantially simultaneously by applying different phasor sequences (corresponding to different candidate directions) to the correlation library. Even when using a single omnidirectional antenna, the different correlation signals are sensitive to energy from different directions.

[0130] By providing a phase shift between signals received at different times, motion compensation can be provided in corresponding different directions.

[0131] Further information regarding determining candidate directions to establish the presence of a reflected signal and the signal environment of the receiver can be found in commonly assigned patent publication number WO2019 / 058119, the entire contents of which are incorporated herein by reference.

[0132] Return to reference Figure 3 Once it is determined that the first signal has been received in the LOS direction between the receiver and the satellite 200a, at step S110, a second local signal is generated based on the attributes of the received first signal in the LOS direction. Recall that in this example, the determination in step S108 is made on one or more L1 channels. Therefore, once it is established that the L1 signal from the satellite 200a is being received along the LOS, the parameters of one or more L5 channels can be set so as to track the LOS L5 signal from the same satellite with confidence. In some examples, the L5 channel may not be activated until it is determined that the L1 signal has been received in the direction of interest, thereby further conserving battery power.

[0133] Therefore, based on the corresponding attributes of the first signal received along the line of sight on the L1 channel, the local signal generator 8-2 of the L5 channel corresponding to the 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. In other words, the L5 channel of the receiver can use the information obtained by processing the L1 signal on the L1 channel to begin tracking the LOS L5 signal from the satellite 200a. It should be noted that it is necessary to perform appropriate transformations on the expected code phase and frequency in order to transform these results obtained from the L1 channel into results suitable for the L5 channel. The frequency band conversion switch unit 26, which communicates with the signal analysis unit 14 and each channel, is 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 appropriate transformations.

[0134] Based on the known difference between the L1 and L5 nominal frequencies, a code phase and frequency transformation of the received one or more L1 signals is performed to an expected code phase and frequency on one or more L5 channels. For example, once the Doppler shift of the L1 carrier frequency is determined based on processing on the L1 channel (e.g., due to satellite and receiver motion and clock errors), an expected Doppler shift correction for the nominal frequency at which the L5 signal will be detectable can be calculated. Similarly, by using the received signal on the L1 channel to calculate a current estimate of the receiver position and time (time of week), an expected L5 code phase can then be calculated based on the current estimate of the receiver position and time. In this way, the properties of the received one or more first signals can be used to calculate expected parameters (e.g., Doppler shift and code phase) for processing (e.g., tracking) L5 signals from the same satellite without the need for a computationally intensive acquisition process.

[0135] In this way, the present invention is able to minimize processing load and save battery resources when tracking L5 signals because the initial acquisition and determination of the expected code phase and frequency can be performed on the L1 signal, which has a lower sampling rate than the L5 signal. In addition, after determining 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 confidence based on the generated local signal for the L5 channel. For example, returning to reference Figure 1 , after determining that the signal from the first satellite 200a is being received along the LOS direction, after generating the L5 local signal based on the L1 processing, the L5 signal received from the satellite 200a can be processed with confidence.

[0136] In contrast, since the L1 signal from the second satellite 200b arrives at the receiver only after being reflected, after processing the L1 signal received from that satellite, it may be decided not to attempt to track the L5 signals from satellite 200b, as they would result in an erroneous solution, thereby wasting computing resources and battery life. Thus, the method may end after step S109 when processing the signal from satellite 200b. This is in contrast to conventional systems, which may attempt to track the L5 signal from satellite 200b if the received L1 signal strength is greater than a predetermined threshold, even if this is entirely due to the reflected signal.

[0137] At step S112, the L5 signal from satellite 200a is received at the receiver. As described above, the properties of the L5 channel of the receiver are set so that the received LOS L5 signal can be tracked immediately, rather than using computing resources to search the code phase and frequency space to acquire the signal. To further reduce the computational load, the tracker of the L1 channel can be stopped once the received L5 signal is being tracked.

[0138] In various embodiments, the method then proceeds to decision step S114 based on whether there are any reflected components (e.g., after analysis of the additional motion compensated correlation signals generated in step S109). If it is determined that there are components received in the LOS direction and reflected components for the particular satellite, the method moves to step S116, where a motion compensated 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 determined LOS direction between the receiver and the satellite, the resulting motion compensated correlation signal is provided with a preferential gain compared to the signal received along the LOS direction for which motion compensation is not provided. Thus, for the particular satellite, Figure 1 For positioning satellite 200a in FIG. 1 , signal components received along LOS direction D1 are advantageously provided with increased gain compared to any reflected components present. Generating motion compensated correlation signals in this manner also helps mitigate multipath effects due to reflected components of the signal.

[0139] In order to reduce the computational load in this step, the motion compensated phasor sequence generated on the L1 channel in step S104 and stored in step S104a can be reused in step S116 in order to avoid the requirement to recalculate the phasor sequence. If the motion of the receiver is substantially the same as when the phasor sequence was constructed, the motion compensated phasor sequence is reused. This requirement can be verified using the sensors of the motion unit 4, for example, to establish that there is no heading change or speed change. On the other hand, if the data from the motion unit indicates that the receiver motion has changed during the time period when the phasor sequence was constructed on the L1 channel, the motion compensation unit 20 recalculates the phasor sequence indicating the current receiver motion during the subsequent time period in which the processing on the L5 channel is performed.

[0140] It will be appreciated that in order to "reuse" the phasor sequence stored in the storage device 17, the phase values ​​need to be appropriately transformed from the L1 channel to the L5 channel based on the wavelength difference between the L1 and L5 signals. Such transformation may be performed in the band conversion switch unit 26.

[0141] The method then proceeds to step S118, in which the signal analysis unit 14 determines an interestingness metric associated with the receiver, such as position, velocity, time, or direction of motion, based on processing of the received L5 signal. Interestingness metrics are typically used to determine a tracking or navigation solution for the receiver. Due to the increased bandwidth of the L5 signal, it is advantageous to use the L5 channel (rather than the L1 channel) when determining interestingness metrics, which allows for increased processing gain and improved positioning accuracy.

[0142] Alternatively, if it is determined that no reflected components are present (e.g., if the receiver is located in an "open sky" environment, rather than Figure 1), the method may optionally proceed directly to step S118, i.e., without generating a motion compensation related signal. Due to the lack of reflected signals, the priority gain provided by motion compensation is not so advantageous in such an open environment, so computing resources may be preserved by not applying motion compensation during 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 increased signal gain and directionality provided by motion compensation.

[0143] Typically, steps S100 - S109 are performed during a first time period, and steps S110 - S118 are performed during a second time period that is later than the first time period.

[0144] As described above, the local signals generated by the local signal generators 8-1, 8-2 are based on the local frequency and phase references 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 a reference signal received from an oscillator reference source, wherein the reference signal has a known or predictable frequency or phase. In this way, errors in the local oscillator 10 can be isolated by eliminating the effects introduced into the received phase or received frequency based on the relative movement between the receiver 100 and the oscillator reference source (from which the reference signal is received along the vector between the two). In such an embodiment, the phasor sequence generated by the motion compensation unit 20 can further indicate the determined offset (e.g., as a function of time). The amplitude and / or phase angle of the phasor sequence generated by the motion compensation unit 20 can be adjusted based on the determined offset (or time series of offsets) between the local oscillator and the oscillator reference source.

[0145] Thus, in an optional embodiment, the method may include determining a component of motion of the receiver and oscillator reference source along a straight line ("line of sight") between the two. By compensating for offsets between the local frequency or phase provided by the local oscillator and the reference signal, the mobile receiver can provide longer coherent integration of the signal than would otherwise be possible. Coherent integration of received signals over a period of one second or longer is possible. This means that the sensitivity of the receiver is improved so that, in combination with the use of motion compensation as described above, weaker positioning signals can be detected and used for positioning calculations. Such an embodiment is particularly beneficial where the local oscillator has greater instability (e.g., quartz oscillators in low-cost devices such as smartphones).

[0146] The oscillator reference source may be a terrestrial 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, such as a GNSS satellite with a high stability atomic local oscillator. The oscillator reference source may be a remote source (e.g., Figure 1 Satellites 200a, 200b in the remote source of oscillators). Importantly, the local oscillator in the remote source of oscillators should be at least more stable than the local oscillator. Further details on the use of a reference source to determine the error in the local oscillator can be found in commonly assigned patent publication number WO2019 / 008327, the entire contents of which are incorporated herein by reference.

[0147] In another example, the error in the frequency or phase reference provided by the local oscillator 10 can be determined by using multiple phasor sequences for each direction, which "test" different hypotheses of the error of the local oscillator 10. For example, in step S104, multiple phasor sequences can be generated, each of which provides motion compensation along the direction of interest, but additionally tests the corresponding multiple different hypotheses of the frequency and / or frequency change rate error of the local oscillator. Therefore, step S106 will accordingly provide multiple motion compensation related signals corresponding to the error hypothesis for the local oscillator 10. The motion compensation related signal with the highest power then indicates the hypothesis that is closest to the true offset or error of the local oscillator. Further details on "testing" different hypotheses of local oscillator errors can be found in commonly assigned patent publication number WO2019 / 063983, the entire contents of which are incorporated herein by reference.

[0148] Typically, the local oscillator error unit 11 uses the received one or more L1 signals to determine errors in the local oscillator 10 (e.g., offsets between a local frequency or phase reference and a received frequency or received phase of a reference signal received from an oscillator reference source). These one or more offsets (or "errors") of the local oscillator 10 determined by processing the L1 signals may be used when processing the one or more L5 signals after determining that the L1 signals are received in the LOS direction. For example, when the received L5 signals are used to generate motion compensated correlation signals in step S116, the phasor sequence generated by the motion compensation unit 20 when processing the received L1 signals further indicating the determined offsets may be reused (through appropriate transformations).

[0149] The above description has focused on a GNSS positioning system where the first signal is a GPS L1 signal in the L1 frequency band and the second signal is a GPS L5 signal in the L5 frequency band. As discussed, this provides the advantage of reducing the processing load by performing initial processing on the L1 signal, which has a lower chip rate than the L5 signal, before committing processing resources to processing the L5 signal. However, embodiments of the present invention may involve a plurality of different sets of first and second signals where it is advantageous to perform initial processing on the first signal in order to determine a measure of interest before the second signal may be processed with confidence.

[0150] For example, the first signal received may be a low bandwidth 5G signal in the FR1 band transmitted from a cellular antenna mast, and the second signal may be a high bandwidth 5G signal in the FR2 band transmitted from the same antenna mast. In yet another 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 in the 5 GHz band from the same access point. For example, such WiFi signals may be used to perform indoor positioning.

[0151] In the above examples, the first and second signals are in respective different frequency bands. However, this is not required, and embodiments of the present invention may be used to process the first and second signals in the same frequency band. For example, the first and second signals may include civilian and military signals in the GPS L1 band. In another example, the signal-to-noise ratio of the first signal may be greater than the signal-to-noise ratio of the second signal, so that the code phase and frequency parameters of the first signal can be easily determined and used in subsequent processing of the second signal. In another example, the first signal may be encrypted, whereby processing the first signal allows a determination that the signal received from the respective remote source is credible. The first and second signals will typically be sent via respective different communication channels.

[0152] It is also contemplated that the first and second signals may correspond to different signal types. For example, the first signal may be a Bluetooth signal, wherein at least one parameter obtained from the first signal is used to receive the second signal as a WiFi signal from a co-located access point.

Claims

1. A method performed in a wireless communication system, comprising the following steps: generating a first local signal; receiving, at a receiver, a first signal from a remote source; determining movement of the receiver; generating a first correlated signal by correlating the first local signal with a 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 compensation related signal, that the first signal has been 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 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; as well as The received second signal is processed using the second local signal to determine an interest metric associated with the receiver and / or associated with a communication link including the receiver. 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. A method according to any one of the preceding claims, wherein the second signal has a greater sampling rate than the first signal.

5. A method according to any one of the preceding claims, wherein the second signal has a larger bandwidth than the first signal.

6. A method according to any one of the preceding claims, wherein the first signal has a greater signal-to-noise ratio than the second signal.

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

8. A method according to any preceding claim, wherein the first signal is in a first frequency band and the second signal is in a second frequency band. 9 . The method of 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. A method according to any preceding claim, wherein the direction of interest is a straight line direction between the receiver and the remote source.

11. The method according to any one of the preceding claims, further comprising: The step of determining at least one property of a first signal received along said direction of interest, and wherein said at least one parameter of said second local signal is based on said at least one property of said first signal.

12. The method of claim 11, wherein the at least one attribute of the first signal is at least one of a code phase and a frequency of the first signal, and wherein the at least one parameter of the second local signal is at least one of an expected code phase or a frequency of a second signal being received along the direction of interest.

13. A method according to any one of the preceding claims, wherein the determination that the first signal has been received along the direction of interest is based on a signal quality measure of the first motion compensated related signal.

14. The method according to any of the preceding claims further includes generating one or more additional first motion compensation related signals based on the determined movement of the receiver along the corresponding one or more additional directions, and wherein the determination that the first signal has been received along the direction of interest is based on multiple first motion compensation related signals.

15. A method according to any preceding claim, further comprising determining whether the received first signal comprises a component received in a direction different from the direction of interest.

16. A method according to any one of the preceding claims, wherein: Processing the second signal comprises: generating a second correlated signal by correlating the second local signal with a received second signal; and Based on the determined movement of the receiver along the direction of interest, motion compensation is provided for at least one of the second local signal, the received second signal and the second related signal, thereby generating a second motion compensated related signal to provide preferential gain for the second signal received along the direction of interest compared to components received in directions other than the direction of interest.

17. The method according to claim 16, wherein: One or more parameters used for providing the motion compensation during generating the second motion compensation-related signal are based on corresponding one or more parameters used for providing the motion compensation during generating the first motion compensation-related signal corresponding to the direction of interest.

18. A method according to any one of the preceding claims, wherein: Providing motion compensation includes: generating a phasor sequence comprising a plurality of phasors indicative of said phase and / or amplitude changes introduced into the received signal due to the determined motion of the receiver, wherein each phasor comprises a phase angle and an amplitude; and The phasor sequence is combined with at least one of the local signal, the received signal, and the correlation signal.

19. The method of claim 18, wherein the first local signal and the second local signal are both based on a local frequency or phase reference provided by a local oscillator, and wherein the phasor sequence is also indicative of an error in the frequency or phase reference provided by the local oscillator.

20. The method according to any one of claims 17 to 19, wherein a phasor sequence used to generate the second motion compensated related signal is based on a phasor sequence used to provide the first motion compensated related signal corresponding to the direction of interest.

21. A computer program product comprising executable instructions which, when executed by a processor in a wireless communication system, cause the processor to perform a method according to any preceding claim.

22. A wireless communication system, comprising: Receiver; a motion unit configured to determine movement of the receiver; as well as One or more processors configured to perform the steps described below: generating a first local signal; receiving, at the receiver, a first signal from a remote source; determining movement of the receiver; generating a first correlated signal by correlating the first local signal with a 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 compensation related signal, that the first signal has been 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 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; as well as The received second signal is processed using the second local signal to determine an interest metric associated with the receiver and / or associated with a communication link including the receiver.

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

24. The system of claim 23, wherein the at least one attribute of the first signal is at least one of a code phase and a frequency of the first signal, wherein the at least one parameter of the second local signal is at least one of an expected code phase or a frequency of a second signal being received along the direction of interest.

25. The system of any one of claims 22-24, 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 system of any one of claims 22-25, wherein the one or more processors are further configured to perform the steps of: generating a second correlation signal by correlating the second local signal with a received second signal; and Based on the determined movement of the receiver along the direction of interest, motion compensation is provided for at least one of the second local signal, the received second signal and the second related signal, thereby generating a second motion compensated related signal to provide preferential gain for the second signal received along the direction of interest compared to components received in directions other than the direction of interest.

27. The system according to any one of claims 22-26, further comprising an addressable memory configured to store one or more parameters for providing motion compensation during generation of the first motion compensation-related signal corresponding to the direction of interest.

28. The system of any one of claims 22-27, wherein the one or more processors are configured to generate a phasor sequence comprising a plurality of phasors indicative of the phase and / or amplitude changes introduced into the received signal due to the determined motion of the receiver, each phasor comprising a phase angle and an amplitude, wherein the phasor sequence is combined with at least one of the local signal, the received signal, and the correlated signal.

29. The system of claim 28, further comprising a local oscillator configured to provide a local frequency or phase reference, and wherein the phasor sequence is also indicative of an error in the frequency or phase reference provided by the local oscillator.

30. The system of any one of claims 22-29, wherein the receiver is configured to receive signals in more than one frequency band.

31. The system of any one of claims 22-30, wherein the one or more processors are configured to perform the method of any one of claims 1-20.

32. The system according to any one of claims 22-31, wherein the system is provided on a single user device.

33. The method or system of any one of claims 8-32, wherein the second frequency band is the L5 GNSS frequency band.

34. A method or system according to any preceding claim, wherein the receiver is a GNSS receiver.

35. A method or system according to any preceding claim, wherein the receiver is implemented on an electronic user device such as a smartphone.

36. A method or system according to any preceding claim, wherein the wireless communication system is a positioning system, preferably a GNSS positioning system.

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