IL257362B2 - High accuracy positioning - Google Patents

Description

September 1 5, 2022 SYSTEM AND METHOD for ENHANCING ACCURACY OF LOCATING MOBILE NETWORK ELEMENTS The Field of the Invention The present invention is related to mobile wireless networks in general and to accurately positioning the mobile devices of the network, in particular.

Background of the invention Many services provided by cellular systems need to know the end terminals position and other parameters like its relative velocity.

The common method in use is based on Global Navigation Satellite System (GNSS) e.g. GPS.

Methods which only rely on cellular signals processing (without GNSS receiver) are applicable for cases where there is no connectivity with the GNSS sources, e.g. in‐door or cases when the GNSS receiver is out of service or not available.

Methods based on cellular positioning are limited in accuracy (in the order of almost 100 meters) and cannot provide a proper answer when required accuracy is in the order of a meter or less.

The presented invention enables enhancing cellular UE and IoT (Internet of Things) devices positioning to the order of centimeters and less.

Summary of the invention The term UE refers herein to User Equipment Many applications need the exact location of the User Equipment terminals or connected Things (for IoT) terminal.

In many cases, connected cellular devices are in the range of at least 3 Remote Radio Heads (RRH) which wirelessly distribute the cellular radio network signals.

RRH are physical layer (layer 1) units which are distributed over the target coverage area to maintain network connectivity with the user’s terminal devices. 25 September 1 5, 2022 Embodiments of the invention provide a system in which user’s terminal devices process the received signals and extract from its parameters the Time Difference (TD) between received signals transmitted by neighboring RRH units.

One exemplary embodiment of the disclosed subject matter is a Multi Carrier or an OFDM/OFDMA device that uses pre‐known pilots or reference signals to measure accurately the time difference between the received arrival time of the signals to its internal clock The system measures the Phase Differential between two neighbors Sub Carriers in the frequency domain after FFT or other Fourier Transform algorithm, where positive phase change means delay, and a negative change means advanced (or the other way depending on the implementation). This The measured phase differential is converted to time delay when it is divided by the Reference Number and multiplied by the sampling clock period, The Reference Number is given by 360 degrees divided by N (the FFT Size).

This result provides the time difference with enhanced accuracy and resolution, better than the sampling clock by a factor of N.

According to some embodiments the system may be used in a receiver for measuring the time of arrival difference by utilizing one or more of the following parameters: the FFT size, the Sampling Clock period, the difference frequency in subcarriers number (1 to n September 1 5, 2022 According to some embodiments the system resolves time difference that is less than the sampling clock by a closed loop process. According to some embodiments one device Initiates transmission of reference signals to the a second device, the second device synchronizes to the received signal and measures the time of arrival relatively to its internal clock, the second device transmits back a known signal including a message that carries the time delay between the received signal and the transmit back signal with enhanced accuracy (resolution time of fractional of the sampling clock) . The initiating transceiver measures the round‐trip delay, subtracts the processing time duration at the second device and divides the result by two to obtain the propagation time between the transceivers. The range between the devices is calculated by multiplying this time by the medium speed of the signal propagation, that for wireless radio communications is the speed of light or speed of audio signal for acoustic wave propagation or other medium.

According to some embodiments when the propagation speed is unknown or is changing in time, a real time calibration is done by transmitting a known signal to a reference device with known range and one or more other unknown range devices. By measuring the known range signal the propagation medium speed is measured. The propagation medium speed is used to calculate the ranges of the other un known devices, measuring the time delay accurately . According to some embodiments a variety of propagation mediums in which the wave signals travels through can be used. Examples for such mediums are air environment for wireless radio, VLC – Visual Light Communication where light Energy is modulated at its LED source for example or the same material in case of acoustic wave like air, water or other etc.

For fiber and other media calculations of time delay calculations can be accomplished when its length is known by using the above measured propagation velocity.

According to some embodiments when the signal transmit time at the antenna is unknown or misaligned and/or shifted in time, the actual transmit time at the antenna can be calibrated by using a known location (or range) device, measuring the propagation time with the misalignment transmit time, by subtracting the known propagation time the indentations misalignment correction can be found. Calibration is done by transmitting known signal to a 81 September 1 5, 2022 reference device (with known range) and to one or more other unknown range devices. By measuring the known range signal the system identifies the transmitter misalignment and utilizes the transmitter misalignment to enhance calculating the ranges of the other unknown range devices, and measuring the time delay with enhanced accurately.

According to some embodiments וn Communication network like 3GPP 4G, 5G WiFi 11ax or other OFDM based or Multi carrier like OFDM/A or SC FDMA, when up converting the transmit signal to VLC (Visual Light Communication) frequencies in the transmitter and down converting in the receiver. By shifting the signal to low IF signal at central frequency in the Range of the BW/2 and adding DC level of the max PtP/2 (half of the Peak to Peak range) and using that signal in a VLC modulator that can be LED based. At the receiver the detected signal from the VLC receiver, (that can be photodiode based, is filtered out of any DC and low frequency and shifted back from the low IF to a complex I, Q baseband signal and delivered to an OFDM/A receiver.

Using this conversion method for existing standards like 4G, 5G and WiFi waveforms and adding the enhanced VLC to the existing network as another frequency band that after the transformation will go throw existing 4G, 5G or WiFi baseband transceiver and the related network associated with it.

In a wireless or VLC network with more than 1 transceiver using one or more reference devices (e.g. a UE) and/or an IoT termination device which location is known enables enhancing the 1accuracy of cellular positioning algorithms competence by finding the location of the unknowns 1devices using the ranging method as describe figure 1and 2D, 3D triangulation as described in 1figure 1. 1 According to some embodiments the method can be used in a wireless or VLC network with 1one or more transceiver devices, using one or more reference transceiver devices e.g. a UE 1and/or an IoT termination device or RRH or other which location is known. 1 When known location synchronized devices transmit orthogonal known reference signals using 1different subcarriers or orthogonal sequences like Hadamard or Zadoff–Chu orthogonal 1sequences at the same time or at different known time to devices of unknown location and to 109 September 1 5, 2022 devices with known location. By including a message carrying their locations information, each 1of the receivers in the network can measure the difference time of arrival between the 1reference signals from the different transmitters. 1 If the transmitting time of the Reference Signal has unknown mismatch in time between the 1transmitters, the known location devices after receiving the Reference Signals can calculate the 1mismatch differences between the transmitters time (Di‐Dj as described in figure 1). This 1mismatch related information distributed back. The network devices that transmitted the 1Reference Signals can retransmit the mismatch information after a more accurate estimation 1since several mismatched data measurements arrived from known location devices. Devices of 1unknown location upon receiving the mismatch data can correct their estimated location and 1distribute it back to the network elements. The Reference Signals transmitters may coordinate 1the alignments of the mismatch relative to the others to achieve the best alignment of all 1devices to have the same time synchronization. 1 This process can continue with rate adapted to the network devices dynamics. 1 A device with unknown location coordinates by a real time protocol a RS sequence and its 1expected receipt time from a known location devices, can after receiving Reference Signals [RS] 1from one or more known location devices along with their locations information, measure the 1time differences between the Reference Signals of the RS signals transmitter devices, enabling 1the device to calculate its location by triangulation or other methods. If the device receives a 1data message related to the mismatch between the time of the transmission of the reference 1signals Di‐Dj, the device can use this information to recalculate its exact location and update 1the network on the correction in their location details. The calculation may be performed in the 1device computer or by virtualizing the calculation to a location server in the cloud that is 1connected to the network and its devices. 1 In LTE systems that transmit using SCS of 15KHz the expected resolution of the ranging process 1is the sampling clock of 2K x 15KHz = 30.720 Msps, giving a sampling period of 32.55ns which 1yields a potential accuracy of 9.76m, the receiver can increase the accuracy by a factor of 132.55/2k which gives ~0.15nanosecond translated to ~4.5cm. 137 September 1 5, 2022 In the receiver that receives OFDMA signals like in LTE OFDMA instead of the sampling rate of 12048 x 15KHz = 30.72MHz a higher sampling rate for example by a factor of 8 (to 245.76 MHz) is 1used. By carrying out a 16K FFT, an enhanced resolution by factor 8 will be accomplished 1yielding an accuracy of less than 1 cm (4.5/8 cm). 1 In a device which receives OFDM/A signals and predicts the Doppler frequency shift to calculate 1the relative velocity of the related transmitter, that enable predicting the phase between 1subcarriers in an OFDM symbol and in addition by using another OFDM symbol to calculate the 1change in the predicted phase due to the doppler shift. From this phase difference divided by 1the time between the OFDM symbols, assuming the device is synchronized (time and reference 1frequency oscillator) with the network, calculating the Doppler shift is possible. 1 The highest identified Doppler frequency shift can be carried out by using neighboring OFDM/A 1symbols in time. 1 For example, to avoid overpassing 360 degrees happening at the OFDMA symbol with 15kHz 1 SCS and with CP of about 70 us, the max observable Doppler is given by 1(SCS+ CP)  14 KHz. 1 To predict the velocity "v" from the Doppler shift "fd" (which is a function of the used frequency), 1 fd= v/Lambda, where Lambda= c/fc. 1 fc is the carrier frequency of the signal. 1 v = (fd /fc)*c 1 Another way is to predict the Doppler shift from auto correlation between the CP information 1that repeats two times in the beginning and the end of each OFDM Symbol. 1 For example, in case of 3GHz carrier we get Lambda = 10 cm than v= 14000x0.1=1400m/s, 1yielding a maximum observable velocity of 5040 km/hr. 1 In case the Doppler is higher, required is to correlate the reference signal with shifted 1subcarriers in the frequency domain since the signal is shifting in the frequency domain by one 1or more bins. In speed of 500km/hr the Doppler shift will be about 1.5kHz which imply about 110% of the SCS subcarriers spacing. This measured velocity provides the speed in the receiver 163 September 1 5, 2022 direction. To calculate the real speed required is performing two consecutive localization 1computing as described above and calculating the direction of the moving device and its speed. 1More measurements of localization and velocity calculations will enable getting the 1acceleration of the Device. 1 According to some embodiments the system utilizes the OFDM/OFDMA signals to measure 1range, velocity, acceleration, localization, direction in a Radar System for detection of things in 1the way for example for autonomic cars. 1 By smart Phone/device using 4G, 5G or other technologies where the transmitted signal from the 1phone is bounced back where in the receiver is using the measurement to predict obstacles 1around the phone and to map them relative to the user. For better performance the system 1utilizes multiple antennae capability with a large antenna elements number as a function of the 1angle and direction resolution and range, or by sharing several such devices information in a car 1which can also share information with other cars for better prediction as well as better direct 1separation/attenuation between the transmitter to the receiver. 1 In a network with fixed and mobile devices, when devices are moving, to compensate the Doppler 1effects of this movement the following method is provided. 1 Each device receiver synchronized with certain errors in time and frequency is measuring its 1Doppler shift 1 The Doppler effects in OFDM/A systems results are including: 1 a. Carrier frequency is shifted due to the relative velocity between the receiver and transmitter. 1The carrier frequency shift fd, is given by: 1 fd = v *fc/c. 1 b. Subcarriers frequency is relatively shifted in line with its subcarrier’s frequency (SCS*k), thus 1subcarrier k relative Doppler shift is given by: 1 fdk = k*SCS*v /c 1 SCS is the OFDM signal Sub‐Carrier Spacing. 189 September 1 5, 2022 Measuring the phase change over the symbol duration enables calculating the Doppler shift and 1the relative velocity "v". 1 To find the symbol start and end we correlate the symbol Cyclic Prefix (CP) which is at the 1beginning and end of each symbol. 1 The doppler shift for sub‐carrier k is given by: 1 fdk1=(SCS*k1*v/c) 1 For k subcarrier, the frequency shift is given by: 1 fdk2=(SCS*k2*v/c) 1 The Phase Change (PC) over the symbol is given by: 1 PCk1=2Π* fdk1*Ts 1 And for k is given by: 2 PCk2=2Π* fdk2*Ts 2 The phase difference between PCkand PCkia given by: 2 PCk‐ PCk1=2Π* fdk2*Ts‐2Π* fdk2*Ts=2Π*( fdk2‐ fdk2)*Ts=2Π*SCS*( k‐ k)*Ts*v/c 2 For two subcarriers at the symbol frequency edges, k‐ k equals N. 2 Ts can be expressed by 1/SCS. 2 get: 2 PCN+‐ PC=∆ф=2Π*SCS*N*(1/SCS) *v/c =2Π*N*v/c 2 And the relative velocity "v" is given by: 2 v=∆ф*c/2Π*N 2 Thus, by measuring OFDM/A signal subcarriers relative phase change, finding the relative velocity 2between the transmitter and the receiver is possible. 2 At the receiver it is possible to cancel the Doppler shift by carrying out resampling, in the time domain, to 2drive ∆ф to zero. 213 September 1 5, 2022 THE BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 2The present disclosed subject matter will be understood and appreciated more fully from the 2following detailed description taken in conjunction with the drawings in which corresponding or like 2numerals or characters indicate corresponding or like components. Unless indicated otherwise, the 2drawings provide exemplary embodiments or aspects of the disclosure and do not limit the scope of the 2disclosure. In the drawings: 2Fig‐1 depicts a scenario where 3 RRH units are linked to 3 UE units, in accordance with some 2embodiments of the disclosed subject matter; and 2 Fig‐2 depicts General Scenario with Non‐Aligned RRH units, in accordance with some 2embodiments of the disclosed subject matter. 2 DETAILED DESCRIPTION 2 Fig. 1 depicts a scenario where 3 RRH units are linked to 3 UE units, in accordance with some embodiments 2of the disclosed subject matter. 2 The UE units receive the signals transmitted by the RRH units. 2 An IoT terminal can replace any of the UE units in Fig‐1. 2 The UE units are depicted as 101, 102 and 103. The RRH units are depicted as 104, 105 and 106. 2 For simplicity it is first assumed that the RRH units are aligned. 2 More general cases will be described in the following. 2 The following defines the parameters presented in Fig‐1. 2 x ij is the propagation time between RRHj and UEi. 2 (rij is the range between RRHj and UEi (rij = c * xij)) 2 Dk is the random time shift of RRHk compared with the System clock. 2 tn is the random time shift of UEn compared with the System clock. 2 The distances between the RRH units are r and r. 2 It is assumed that the exact location of the RRH units and of the Reference UE (UE) are premeasured and 2are stored at the Positioning Server data base. 239 September 1 5, 2022 Each UE measures and determines the TD between received signals related to the RRH units. 2 UE (104) receives 3 replicas of the signals, one from each RRH, at following time stamps. 2  From RRH(101) at D+x+t2 From RRH(102) at D+x+ t2 From RRH(103) at D+x+ t2 UE (105) will receives 3 signals, one from each RRH, in the following time stamps. 2  From RRH (101) at D+x+t2 From RRH (102) at D+x+ t2 From RRH (103) at D+x+ t2 UE (106) will receives 3 signals, one from each RRH, in the following time stamps. 2  From RRH (101) at D+x+t2 From RRH (102) at D+x+ t2 From RRH (103) at D+x+ t2 1. UEi Time Difference (TD) Determination Method 2 To boost the measurements accuracy the following method is used to determine the received signals TD. 2 UEi measures the Phase Difference (PD) between orthogonal components (Subcarriers in case of 2OFDM/OFDMA) in the received signal symbols. To avoid the modulation impact UEi refers to Reference 2Signals (RS) which are part of the received signals orthogonal components included in the received 2symbols. 2 Assuming the first RS is in the kth bin and the next RS is in the jth bin of the symbol IFFT signal, then the PD 2between the kth and jth bin RS in the symbol time of the RRH received signal will be given by: 2 PDkj(1)=2Π *(j‐k) * ∆f*(Tsym +D) 2 For the symbol received from RRH the PD is given by: 2 PDkj(2)=2Π * ∆f *(j‐k)*( Tsym + D+ τ) 264 September 1 5, 2022 Where ∆f is the Sub‐Carriers Spacing (SCS) between the signal components, (e.g. OFDM signal), and "τ" is 2the time difference between the received signals due to the difference in range between the RRH units. 2 For example, at UE it is x‐xfor signals received from RRH and RRH. 2 PDkj(21), the PD between the signals received from RRH and RRH is given by: 2 PDkj(21) = PDkj(2) ‐ PDkj(1)= 2Π * ∆f *(j‐k)*( Tsym + D+ τ) ‐ 2Π *(j‐k) * ∆f*(Tsym +D) 2 After opening the brackets, we get: 2 PDkj(21) = 2Π * ∆f *(j‐k)*(D‐ D1+τ) 2 Thus τ, the time difference between the received signals from RRH and RRH due to the range 2difference, is given by: 2 τ = PDkj(21)/2Π * ∆f *(j‐k) ‐ (D‐ D) 2 For UEi, xi2‐xi1, the TD for the signals received from RRH1 and RRH2 will be: 2 x i2 ‐x i1 = PD kj (21)/2Π * ∆f * (j‐k) ‐ (D ‐ D ) 2 For J=k+1 we get: 2 xi2‐xi= PDkk+1(21)/2Π*∆f ‐ (D‐ D) 2 2. From the measurements done by UE (the reference UE), it is possible to find the temporal 2random difference between the RRH units. 2 This time differences D‐D, D‐D and D‐D measured at the time stamp of the measurements done by 2UE and UE is used at the location server to compensate and "calibrate" the reported measurements 2done by UE and UE. 2 As the position of UE is known, r, r and r are also known and x11, xand xcan be calculated by 2dividing the distances by "c" (light propagation velocity). 2 Thus, D‐ D can be found at any instant by using the above equation. 2 D ‐ D = PD kj (21)/2Π * ∆f * (j‐k) ‐ (x ‐x ) 2 The same can be done for RRH and RRH and by that D‐ D1 can be found. 289 September 1 5, 2022 D ‐ D = PD kj (31)/2Π * ∆f * (j‐k) ‐ (x ‐x ) 2 By that (D‐D) and (D‐D) at measurements time stamp can be determined and its impact on other UE 2measurements can be compensated. 2 UE and UE reported measurements provide PDkj(21) and PDkj(31) giving, 2 x‐x= PDkj(21)/2Π*∆f *(j‐k) ‐ ( D‐ D) 2 x‐x= PDkj(31)/2Π*∆f *(j‐k) ‐ ( D‐ D) 2 UE ranges rand rfrom RRH and RRH respectively can be calculated using the above equations, 2yielding: 2 r= c*(x+ PDkj(21)/2Π*∆f *(j‐k)‐(D‐D)) 2 r= c*(x+ PDkj(31)/2Π*∆f *(j‐k)‐(D‐D)) 2 "c" is the light propagation velocity. 3 Referring to the triangle created by UE, RRH and RRH and by using the trigonometric cosine rule, we 3get: 3 r2 = r+ (r+r) – 2*r23*(r+r) * cos(Θ) 3 Substituting r from the above equation, results in: 3 (1) x2 = (x+ PDkj(31)/2Π*∆f *(j‐k)‐(D‐D))+(1/c)*(r+r) – 2* (1/c)*(x+ PDkj(31)/2Π*∆f *(j‐k)‐(D‐ 3D)) *(r+r) * cos(Θ) 3 The same is done for the triangle of UE, RRH and RRH. 3 And the outcome is: 3 r2 = r+ (r) – 2r23*r * cos(Θ) 3 After replacing r and r23, using the above equations, the result is: 3 (2) (x+ PDkj(21)/2Π*∆f *(j‐k)‐(D‐D)) = (x+ PDkj(31)/2Π*∆f *(j‐k)‐(D‐D))+ (r/c) – 2*(1/c)*(x+ 3PDkj(31)/2Π*∆f *(j‐k)‐(D‐D)) *r * cos(Θ) 3 From the two equations (1) and (2) xcan be determined. 313 September 1 5, 2022 Having x, r21, rand rcan be calculated. 3 Knowing these distances, the positioning server, by triangulation, can find the location of UEat the instant 3of the measurement. 3 The same can be carried out for UE and any other user’s terminals or IoT terminal. 3 For the general case where RRH, RRH and RRH are not aligned, as depicted in Fig‐2. 3 The calculation is like in the above. 3 The three RRH units in Fig‐2 form a triangle which all its parameters (angles and sides) are exactly known. 3 For the tringle connecting UE, RRH and RRH the situation is changed compared with the situation in Fig‐ 31. 3 The angle against r is including Θ and an additional part Γ (a known angle) which is the angle between r 3and r (the side connecting RRH and RRH) 3 For the tringle connecting UE, RRH and RRH the situation is with no change. 3 The outcome is the following two equations. 3 r2 = r+ r2 – 2r23*r*cos(Θ+Γ) 3 r2 = r+ (r) – 2r23*r * cos(Θ) 3 From which, by the same process as above r, r and r, can be driven. 3 3. For a 3D case, the PD measurements and related ranges calculations are adequate for a 3D 3scenario. The only exception is in the triangulation calculation. 3 The triangulation should relate to a projection on a flat surface. 3 By that it is possible to find the range projection by multiplying the range by the cosine of the angle Alfa 3between the flat surface (floor) and the line connecting the RRH unit with the terminal. 3 Thus, r21_3D will be given by: 3 r21p = r21*cos  3  can be calculated from arcsine[(H‐HUE)/r] 337 September 1 5, 2022 Thus, 3 r 21p = r 21* cos{arcsine[(H‐HUE)/r]} 3 r21p is range projection used for the 3D positioning calculations. 3 r is the actual distance which was found from the above measurements and related calculations. 3 His RRH above floor height. 3 HUE is the UE height above the floor (can be found by a UE application or predefined). 3 4. For an LTE cellular system running over a radio channel having a bandwidth of B MHz the sampling 3rate is the multiple of the FFT size (N) by the symbol rate (for orthogonality it is the same as the 3Sub‐Carrier Spacing‐SCS for an OFDM modulated signal). 3 For example, for B=20MHz, N=2K and SCS of 15KHz, the sampling rate is 30.72 M[samples/sec]. 3 This is about 30 Nano seconds sampling period (less than 10 meters). 3 For Broadband channels the bandwidth is expected to be over 10 times wider and the 3 FFT size is twice or more (4K and over). The SCS is higher to cope with the phase noise. 3 For 60 KHz sub‐carriers spacing and FFT size of 4K, the SR is 245.760 M[samples/sec]. 3 And the sampling period is 4.069 nsec. 3 At this case the expected accuracy is at the range of less than 4.069ns (about 1.2 meter). 3 By using the above method, UE TD measurements precision is boosted. Positioning measurement 3accuracy using presented method enables precision in the range of centimeters and less. 3 For in use positioning methods accuracy is limited by the SR, but by measuring the Phase Difference (PD) 3between orthogonal components in the received signal symbol’s transmitted by the RRU units the 3accuracy of TD measurement is increased. 3 By measuring the PD for Reference Signals (RS) and further improving the measurement by averaging over 3several RS in the symbol (as configured by the system) and over several OFDM symbols, it is possible to 3enhance the measurement resolution and accuracy results as presented in the following. 362 September 1 5, 2022 The Phase Difference (PD) between neighboring orthogonal subcarriers in the delayed and non‐delayed 3received signals to boost the accuracy of determining the TD. 3 A one sample shift in time (4.069 nsec) domain relative to the original IFFT in the transmitter causes a 2 pi 3(360 degree) rotation along the symbol sub‐carries in frequency domain. 3 So, if a training sequence of all ones are transmitted, at the receiver in the frequency domain, the sub‐ 3carriers relative phase is rotated along the symbol from zero to 2 pi (one period). For 2 samples shift the 3phase rotation is of two periods (4pi) etc. 3 So, by measuring the phase difference between two neighboring subcarriers and averaging over other 3two neighboring used sub‐carriers in the symbol yields a better phase shift between neighboring 3subcarriers measurement resulting in a more accurate PD measurement. 3 Multiplying the measured phase difference between two neighboring subcarriers by N (4096) and dividing 3by 2pi, yields the number of periods along the symbol. 3 Multiplying the number of periods in a symbol by 1/fs (sampling period) results in the time delay which is 3resolved to a fraction of the sampling period. Theoretically accuracy can go down to 1/(fs*N), at the order 3of a mm. 3 Repeating this process for the second received signal, received from another RRH, and by subtracting the 3calculated time delays and including the time shift "calibration" (for UE it is D‐ D), yields the time 3difference, TD, in an accuracy of sqrt2*[1/(fs*N)]. 3 Following the above example with N=4096 and fs =245.760 MHz produces 1/245.76/4096 yielding a result 3in the range of 0.001 nsec equivalent to a range resolution of 0.3 mm. 3 For 1 cm resolution the factor with the above resolution is about 32, which provides 5 bits less in signal 3processing quantization. 3 Fig‐2 presents a general scenario a with non‐aligned RRH units. The same parameters as for Fig‐1 were 3used in this drawing. 3 The UE units are depicted as 104, 106 and 103. The RRH units are depicted as 101, 102 and 103. 3 The terminology used herein is for the Purpose of describing particular embodiments only and is not 3intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are 3intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be 390 September 1 5, 2022 further understood that the terms "comprises" and/or "comprising," when used in this specification, 3specify the presence of stated features, integers, steps, operations, elements, and/or components, but 3do not preclude the presence or addition of one or more other features, integers, steps, operations, 3elements, components, and/or groups thereof. 3It should be noted that, in some alternative implementations, the functions noted in the block of a 3figure may occur out of the order noted in the figures. For example, two blocks shown in succession 3may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the 3reverse order, depending upon the functionality involved. 398

Claims (9)

July 1 1, 2023 Claims

1. A method; the method comprises:receiving, by a receiver, an OFDM signal (orthogonal frequency-division multiplexing )or an OFDMA signal (orthogonal frequency-division multiple access); measuring a phase differential between at least a pair of sub carriers in said signal; converting said differential into time difference between measured arrival time of said signal and an actual arrival time of said signal; said measured arrival time being measured by a sampling clock, said measured arrival time being utilized for measuring a location of a device transmitting said signal and by said time difference enhancing accuracy of said measured arrival time and, thereby, enhancing accuracy of said location.

2. The method of claim 1 wherein said enhancing accuracy is below samplingclock period.

3. The method of claim 1, further comprising averaging measurement of saidphase differential between a plurality of pairs, wherein number of said pairsof subcarriers or the distance between said pair is configured in accordancewith required accuracy and averaging enhancement.

4. The method of claim 1 further comprising if said difference is less than thesampling clock, providing a closed loop process; said close loop comprisingby a first device Initiating transmission of a reference signals to the a seconddevice, by said second device synchronizing a received signal andmeasuring said time difference , transmitting back a known signal saidknown signal comprising said time delay; by said first device measuring around-trip delay, calculating propagation time between said first device andsaid second device and multiplying said propagation time by the mediumpropagation speed of said signal

5. The method of claim 1 further comprising increasing sampling rate therebyincreasing said accuracy.

6. The method of claim 1 wherein said pair of subcarriers being a pair ofneighbors in said signal.

7. The method of claim 1 further comprising predicting Doppler frequencyshift and calculating the relative velocity of a related transmitter.

8. The method of claim 1, further comprising measuring range, velocity,acceleration, localization, direction in a Radar System for detecting orestimating items causing a transmitted signal to bounce back. July 1 1, 2023

9. The method of any one of claim 1 and claim 6 further comprisingcompensating a doppler effect as a result of mobility.