US-12618957-B2 - Time of arrival estimation

Abstract

A method is disclosed for determining a signal's time of arrival at a receiver device, the signal being transmitted by a transmitter device to the receiver device. The method comprises correlating the signal as transmitted by the transmitter device and the signal as received by the receiver device with each other. The signal comprises in its frequency spectrum a first signal component spanning a first frequency range, a second signal component spanning a second frequency range and a third signal component spanning a third frequency range. The first frequency range and second frequency range are separated by a first intermediate frequency range that does not contain a signal component of the signal. The second frequency range and third frequency range are separated by a second intermediate frequency range that does not contain a signal component of the signal. The method further comprises, based on the performed correlation, determining said time of arrival.

Inventors

• Christiaan Christoffel Johan Tiberius
• Gerardus Johannes Maria Janssen
• Jeroen Koelemeij

Assignees

• KONINKLIJKE KPN N.V.

Dates

Publication Date

20260505

Application Date

20200327

Priority Date

20190416

Claims (13)

1. 1 . Method for determining a signal's time of arrival at a receiver device, the signal being transmitted by a transmitter device to the receiver device, the method comprising: correlating the signal as transmitted by the transmitter device and the signal as received by the receiver device with each other, wherein the transmitter device is a base station of a mobile communication system, wherein the signal comprises in its frequency spectrum: a first signal component spanning a first frequency range, a second signal component spanning a second frequency range, and a third signal component spanning a third frequency range, wherein the first frequency range and second frequency range are separated by an intermediate frequency range that does not contain a signal component of the signal, and the second frequency range and third frequency range are separated by a second intermediate frequency range that does not contain a signal component of the signal, wherein a lowest frequency present in the signal and a highest frequency present in the signal are separated by a frequency range of at least 250 MHz wide, and the method comprising determining said time of arrival based on the performed correlation.
2. 2 . The method according to claim 1 , further comprising based on the determined time of arrival, determining a distance between the transmitter device and the receiver device.
3. 3 . The method according to claim 1 , wherein an autocorrelation function of the signal as transmitted comprises a central peak of a first height at zero time displacement and one or more side peaks at nonzero time displacements, wherein all side peaks of the autocorrelation function are lower than 0.9 times the first height, preferably lower than 0.8 times the first height, more preferably lower than 0.7 times the first height, most preferably lower than 0.6 times the first height.
4. 4 . The method according to claim 1 , wherein the lowest frequency present in the signal and the highest frequency present in the signal are separated by a frequency range of at least 500 MHz wide.
5. 5 . The method according to claim 1 , wherein the first frequency range has a center frequency f c 1 and the second frequency range has a center frequency f c 2 and the third frequency range has a center frequency f c 3 , and wherein correlating the signal as transmitted and the signal as received with each other comprises: obtaining a down-converted first signal component as received obtainable by down-converting the first signal component as received over a first frequency shift range, the down-converted first signal component as received having a center frequency f c 3 ↓ , obtaining a down-converted second signal component as received obtainable by down-converting the second signal component as received over a second frequency shift range, the down-converted second signal component as received having a center frequency f c 2 ↓ , obtaining a down-converted third signal component as received obtainable by down-converting the third signal component as received over a third frequency shift range, the down-converted third signal component as received having a center frequency f c 3 ↓ , and correlating the down-converted first signal component as received and a down-converted first signal component as transmitted with each other in order to determine a first correlation signal, wherein the down-converted first signal component as transmitted is obtainable by down-converting the first signal component as transmitted over the first frequency shift range, and the first correlation signal has a center frequency f c 3 corr , correlating the down-converted second signal component as received and a down-converted second signal component as transmitted with each other in order to determine a second correlation signal, wherein the down-converted second signal component as transmitted is obtainable by down-converting the second signal component as transmitted over the second frequency shift range, and the second correlation signal has a center frequency f c 2 ,corr , correlating the down-converted third signal component as received and a down-converted third signal component as transmitted with each other in order to determine a third correlation signal, wherein the down-converted third signal component as transmitted is obtainable by down-converting the third signal component as transmitted over the third frequency shift range, and the third correlation signal has a center frequency f c 3 ,corr , frequency shifting the first correlation signal, the frequency shifted first correlation signal having a center frequency f c 1 ,corr,shifted , frequency shifting the second correlation signal, the frequency shifted second correlation signal having a center frequency f c 2 ,corr,shifted , and frequency shifting the third correlation signal, the frequency shifted third correlation signal having a center frequency f c 3 ,corr,shifted , such that ( f c 1 , ↓ - f c 1 ) + ( f c 1 , corr , shifted - f c 1 , corr ) = ( f c 2 , ↓ - f c 2 ) + ( f c 2 , corr , shifted - f c 2 , corr ) = ( f c 3 , ↓ - f c 3 ) + ( f c 3 , corr , shifted - f c 3 , corr ) , and summing the frequency shifted first, second and third correlation signals.
6. 6 . The method according to claim 1 , wherein correlating the signal as transmitted by the transmitter device and the signal as received by the receiver device with each other comprises determining a correlation in accordance with R x ⁡ ( τ ) = ∑ k = 1 K ⁢ R x k b ⁢ b ⁡ ( τ ) ⁢ e j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ f a k ⁢ τ , wherein j = - 1 , the k th signal component of the signal is described by Re ⁢ { x k b ⁢ b ⁡ ( t ) ⁢ e j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ f c k ⁢ t } , the signal as transmitted by s t ⁡ ( t ) = ∑ k = 1 K ⁢ Re ⁢ { x k , t b ⁢ b ⁡ ( t ) ⁢ e j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ f c k ⁢ t } , the signal as received by s r ⁡ ( t ) = ∑ k = 1 K ⁢ Re ⁢ { x k , r b ⁢ b ⁡ ( t ) ⁢ e j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ f c k ⁢ t } , the k th signal component of the signal spans a frequency range having f c k as center frequency, and R x k bb ⁡ ( τ ) = 〈 ( x k , r bb ) * ⁢ ( t ) ⁢ ( x k , t bb ) ⁢ ( t + τ ) 〉 , where <.> denoted averaged over time, and wherein f a k = f c k - f c , wherein f c is the center frequency of the signal as transmitted.
7. 7 . The method according to claim 1 , comprising the receiver device receiving the signal from the transmitter device using one or more antennas.
8. 8 . A receiver device comprising: one or more antennas for receiving a signal from a transmitter device; and a data processing system including at least one processor configured to: correlate the signal as transmitted by the transmitter device and the signal as received by the receiver device with each other, wherein the transmitter device is a base station of a mobile communication system, wherein the signal comprises in its frequency spectrum: a first signal component spanning a first frequency range, a second signal component spanning a second frequency range, and a third signal component spanning a third frequency range, wherein the first frequency range and second frequency range are separated by an intermediate frequency range that does not contain a signal component of the signal, the second frequency range and third frequency range are separated by a second intermediate frequency range that does not contain a signal component of the signal; wherein a lowest frequency present in the signal and a highest frequency present in the signal are separated by a frequency range of at least 250 MHz wide; and determine the signal's time of arrival at the receiver device based on the performed correlation.
9. 9 . A method for transmitting a ranging signal, the method comprising: transmitting the ranging signal by a transmitter device being a base station of a mobile communication system, wherein the ranging signal comprises in its frequency spectrum a first signal component spanning a first frequency range and a second signal component spanning a second frequency range and a third signal component spanning a third frequency range, the first frequency range and second frequency range being separated by a first intermediate frequency range that does not contain a signal component of the signal and the second frequency range and third frequency range being separated by a second intermediate frequency range that does not contain a signal component of the ranging signal, wherein a lowest frequency present in the signal and a highest frequency present in the signal are separated by a frequency range of at least 250 MHz wide.
10. 10 . A transmitter device being a base station of a mobile communication system, the transmitter device comprising a data processing system including at least one processor configured to perform the method of claim 9 .
11. 11 . A non-transitory computer-readable medium comprising a computer program, the computer program comprising instructions which, when the program is executed by a data processing system, cause the data processing system to carry out the method according to claim 9 .
12. 12 . A data processing system comprising at least one processor configured to perform the method according to claim 1 .
13. 13 . A non-transitory computer-readable medium comprising a computer program, the computer program comprising instructions which, when the program is executed by a receiver device comprising at least one processor, cause the at least one processor to: correlate a signal as transmitted by a transmitter device and the signal as received by the receiver device with each other, wherein the transmitter device is a base station of a mobile communication system, wherein the signal comprises in its frequency spectrum: a first signal component spanning a first frequency range, a second signal component spanning a second frequency range, and a third signal component spanning a third frequency range, wherein the first frequency range and second frequency range are separated by an intermediate frequency range that does not contain a signal component of the signal, the second frequency range and third frequency range are separated by a second intermediate frequency range that does not contain a signal component of the signal, wherein a lowest frequency present in the signal and a highest frequency present in the signal are separated by a frequency range of at least 250 MHz wide; and determine the signal's time of arrival at the receiver device based on the performed correlation.

Description

This application is the U.S. National Stage of International Application No. PCT/NL2020/050211, filed Mar. 27, 2020, which designates the U.S., published in English, and claims priority under 35 U.S.C. § 119 or 365(c) to Netherlands Application No. 2022957, filed Apr. 16, 2019. The entire teachings of the above applications are incorporated herein by reference. FIELD OF THE INVENTION This disclosure relates to a method for determining a signal's time of arrival at a receiver device, the signal being transmitted by a transmitter device to the receiver device, in particular to such method wherein the signal comprises in its frequency spectrum signal components in disjoint frequency ranges. Further, this disclosure relates to methods for determining said signal, for generating said signal, for transmitting said signal, a transmitter device, a receiver device, the signal itself, a data processing system, a computer program and a system comprising said transmitter device and receiver device. BACKGROUND High accuracy time of arrival (ToA) estimation of a signal and the related ranging accuracy, especially in a multipath radio environment, require a high time resolution. Since the achievable time resolution is inversely proportional with the bandwidth of the signal used, accurate ToA estimation requires a (very) large bandwidth signal. Through cross correlation of the received signal with the known transmitted signal, the width of the obtained correlation peak is inversely proportional with the signal's bandwidth. Decimeter accuracy ranging through nanosecond timing accuracy requires a signal bandwidth in the order of a GHz. However, such a wide bandwidth of radio spectrum, in frequency ranges which allow propagation distances of interest for positioning systems, are not freely available and would be extremely expensive, and difficult to arrange. U.S. 2005/0175075 A1 discloses a satellite position pinpointing receiver intended to carry out combined processing of a first received radio signal and a second received radio signal which differ in frequency. U.S. 2009/0219201 A1 discloses a satellite positioning receiver having at least one receive channel. Each receive channel is intended to perform a combined processing of a first and a second radiofrequency signals separated in frequency. WO 2010/062606 A1 discloses techniques for determining time of arrivals of signals in a wireless communication network. J. Issler, M. Paonni and B. Eissfeller, “Toward centimetric positioning thanks to L- and S-Band GNSS and to meta-GNSS signals,” 2010 5th ESA Workshop on Satellite Navigation Technologies and European Workshop on GNSS Signals and Signal Processing (NAVITEC), Noordwijk, 2010, pp. 1-8 as well as Paonni et al; “GNSS Meta-signals: Coherently Composite Processing of Multiple GNSS Signals”; Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 2592-2601 disclose a GNSS Meta-signals concept. Herein, two signals are processed as the two main lobes of a generalized AltBOC signal. U.S. 2005/0050130 (“U.S. 130”) discloses a method for ranging in a multi-band OFDM (Orthogonal Frequency Division Multiplexing) communications system. As known, in OFDM communications systems, numerous closely spaced orthogonal sub-carrier signals in overlapping subbands of the spectrum are emitted to carry data. The method of U.S. 130 comprises a first device transmitting a first signal on a first plurality of subbands to a second device and receiving a second signal on a second plurality of subbands from the second device. Based on the first and second signals, a separation is calculated between the first and second device. The method thus uses a plurality of overlapping subbands to transmit ranging signals. Allegedly this would be as opposed to the techniques that were known prior to U.S. 130, which techniques would involve using only one subband to transmit a ranging signal. The use of a plurality of subbands would be advantageous, because herewith the effective bandwidth that is used to transmit ranging signals can be increased resulting in a higher accuracy. A further advantage of this method would be that the number of overlapping subbands that are used for transmitting the ranging signals need not be fixed. Thus, if there are many adjacent subbands available for use, then a large number of subbands can be used, and if only a small number of subbands are available, then only a few subbands are used. The method of U.S. 130 still leaves room for improving the accuracy with which a separation between two devices can be determined. Therefore, it is an object of the present disclosure to provide a method that allows to determine a time of arrival with a higher accuracy. SUMMARY To that end, a method, optionally carried out by a data processing system, is disclosed for determining a signal's time of arrival at a receiver device, the sign