Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
  • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
  • G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
  • G01S19/10—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals
  • G01S19/11—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters

Definitions

• Disclosed invention relates to an indoor positioning system where signals emitted by GNSS satellites are utilized. Disclosed invention more specifically concerns indoor positioning systems whereby coverage by conventional GNSS signals are improved to a greater extent to bypass shortcomings resulting from weak signals and path loss of radio frequency signals resulting therefrom; as well as reducing the design constraints imposed thereupon by legal restrictions on GNSS frequency bands.
• GNSS Global navigation satellite systems
• GPS Global navigation satellite systems
• Galileo Galileo
• GLONASS BeiDou
• BeiDou became quite popular in recent years and they have wide usage in many areas. Since their introduction in the eighties, locating objects and individuals on the surface of the earth is greatly facilitated.
• GNSS Global navigation satellite systems
• former systems have also been utilized widely in civilian use due to low-cost GNSS receivers becoming easily available over time.
• Such uses cover a wide range from asset tracking to navigation in maritime applications as well as speed tracking and location services used for everyday urban use.
• the global indoor positioning market was forecasted to be expanding by 42% compound annual growth rate from 2017 to 2023. The forecasted growth promises the requirement for newer technologies and methods in the field.
• One such prevalent method for indoor positioning is realized through repeaters.
• EP 2878974 A2 teaches a method, device, and circuit for determining the position of a mobile cellular communication device in disclosures.
• a pseudolites positioning signal is received in a first frequency band at an antenna of the mobile cellular communication device.
• the pseudolites signal is converted from the first frequency band to a Global Navigation Satellite System (GNSS) frequency band to obtain a corresponding positioning signal in the GNSS frequency band.
• the converted positioning signal at the mobile communication device is delivered to a GNSS chipset of the mobile cellular communication device.
• the GNSS chipset determines the position of the mobile cellular communication device using the converted positioning signal.
• GNSS Global Navigation Satellite System
• CN 106767831 A provides a simulated GNSS signal-based indoor locating system comprising a plurality of outdoor receivers, an indoor simulation signal generator, simulation signal emitters and indoor locating modules.
• Said plurality of outdoor receivers are used for collecting self-locating information and sending the information in a telegraph text signal manner;
• the indoor simulation signal generator is used for generating simulation signals with simulation satellite band and frequency according to received GNSS locating information in the telegraph text signal manner;
• the simulation signal emitters are arranged in different directions indoors, and used for emitting simulation navigation signals indoors; and the indoor locating modules are used for receiving the simulation signals emitted by the simulation signal emitters for locating.
• the system can be used for achieving indoor locating based on outdoor GNSS signals.
• EP 1720032 B1 discloses a GPS-based indoor positioning system as follows: GPS primary positioning signals received by a single outdoor receive antenna are up-converted to four different carrier frequencies in the 2.4 GHz ISM band and the upconverted signals are connected to 4 physically distant transmit antennas with RF cables to be transmitted inside the building, the transmit antennas serving at the same time as access points of a WLAN which is used for transmitting additional positioning data like the positions of the transmit antennas and the signal delay times associated with them.
• the secondary positioning signals received from the transmit antennas i.e. down-converting each of them during an assigned time slot, and determining clock bias differences in the receiver the position of the latter is determined using TDOA algorithms.
• US 2012286992 A1 provides a GPS-based indoor positioning system as such: It comprises at least three directional GPS antennas for picking up specific GPS signals coming from at least three GPS satellites, at least three RF GPS repeaters for amplifying GPS signals coming from directional GPS antennas, at least three GPS antennas for transmitting GPS signals coming from RF GPS repeaters to indoor, at least one GPS receiver for picking up GPS signals coming from GPS antennas by its antenna novel position calculation method and relates to increase the coverage of the outdoors GPS signals to indoors.
• the code-based algorithm looks at the variation in behavior of the estimated position in cases of error in an initial position and in cases without error. Such variations give one a way to find the correct initial position with a search algorithm, much the same way as for carrier phase ambiguity resolution.
• This indoor positioning software has two main blocks, one of which is initial position estimation, based on pseudorange observations and the other is the carrier phase positioning component.
• the algorithm doesn't require knowledge of the initial position and uses pseudorange and carrier-phase observations. Indoors, one can clearly use only a single GPS satellite out of all those signals received at the roof antenna.
• disclosed invention constructs an indoor positioning system based on multiple GPS repeaters and tests of which had reportedly demonstrated centimeter- level indoor initialization accuracy in the low multipath environment and the possibility to build indoor positioning systems based on multiple GPS repeaters as the signal sources.
• Lymberopoulos et al. in their study titled "A Realistic Evaluation and Comparison of Indoor Location Technologies: Experiences and Lessons Learned” report their findings on the location error of 22 approaches through a competition of indoor location technologies, whether they are infrastructure- free or infrastructure-based, in 22 groups on a 300 meter-square evaluation space.
• Lymberopoulos et al. were found the persistence of deployment overhead as most such approaches were custom; and the invariable failure of any indoor location approach to compare to GPS-like results achieved outdoors.
• the primary object of the present invention is to provide an indoor positioning system.
• Another object of the present invention is to provide an indoor positioning system using GNSS signals remediated with the use of a frequency lower than GNSS signal frequency, such as the ISM band at 433 MHz.
• Yet another object of the disclosed invention is to provide an indoor positioning system using GNSS signals remediated through the use of lower frequency than GNSS frequency (such as the ISM band at 433 MHz) with improved indoors coverage and circumvention of legal restrictions on GNSS frequency band.
• a further object of the disclosed invention is to provide an indoor positioning system using GNSS signals and lower frequency unlicensed RF band whereby signal fidelity is preserved while free-space path loss is reduced due to the use of lower frequency.
• a further object of the disclosed invention is to provide an indoor positioning system using GNSS signals and lower frequency unlicensed RF band whereby signal coverage is increased due to transmitting higher power levels.
• a further object of the disclosed invention is to provide an indoor positioning system using GNSS signals and lower frequency unlicensed RF band whereby signal penetration is improved due to operation at lower frequency signals.
• a still further object of the disclosed invention is to provide a triangulation based indoor location determining method comparable in accuracy to regular outdoor GNSS TDOA/triangulation methods in the art.
• the disclosed invention proposes a cost-effective, readily deployable and accurate indoor positioning system that is based on GNSS satellite navigation technologies.
• Disclosed invention is superior to the solutions documented in the art in that it displays remarkable accuracy whilst rendering legal restrictions in established GNSS frequency bands obsolete since it relies on remediation of location signals over a different frequency band, namely the ISM band at a lower frequency than GNSS frequency such as 433 MFIz.
• GNSS frequency signals could be available in several types, such as the ones found in GPS, GLONASS, Galileo bands.
• GNSS signals that are broadcast by satellites are received by directional GNSS active antennas, subsequent to which said signals will be amplified by active antennas and then downconverted to a lower frequency of 433 MHz for transmission indoors and these signals will be picked up by 433
• the main strength of the indoor positioning system proposed hereby lies in its downconversion-signal conditioning-upconversion scheme and a novel location finding algorithm that eliminates issues arising from non-line- of-sight (NLOS) propagation between satellites and the indoor receiver. Due to compactness and readiness in implementation to existing GNSS infrastructure, as a corollary, it also proposes a cost advantage compared to similar solutions in the art.
• NLOS non-line- of-sight
• the "GNSS-to-lower frequency ISM and lower frequency ISM-to-GNSS" operation of the indoor positioning system as disclosed in the present invention provides also a reduced free space path loss due to operation at a lower frequency, and since it is readily adaptable and operable within a matter of minutes, it poses great usefulness in emergencies such as fire, earthquake and homeland security applications.
• the disclosed system is also greatly viable for depots/storage, markets, hospitals and also manufacturing plants due to its cost advantage.
• the invention therefore broadly relates to a method of and system to liberate indoor positioning approaches from legal restrictions (especially concerning amplification larger than 45 dB in GNSS band), increase coverage robustness of such applications as well as to reduce free path loss and decrease deployment costs, and accomplishing such in a novel radio frequency front-end specifically designed for remediation of actual GNSS signals.
• 433 MHz ISM band transmit power level is limited to 10 dBm, which is 87 dB higher than the limit on GPS frequency transmit power level.
• Advancing the system taught in EP 1720032 Bl, disclosed invention solves many shortcomings that may arise from utility of signals in frequency bands higher than that of GNSS such as high interference levels in Wi-Fi (IEEE 802.11) as well as common household appliances such as microwave ovens, the need of laying long RF cable infrastructure due to physically separate transmit antennas in question, need for synchronization of receiver for each transmit antenna slot; as well as an inevitably increased path loss at 2.4 GHz as well as a remarkably deteriorated penetration capability through walls.
• Fig. 1 demonstrates a three-repeater system for two-dimensional indoor positioning according to the present invention.
• Fig. 2 demonstrates an RF downconverter (transmitter of the repeater system) circuit diagram for the indoor positioning system according to the present invention.
• Fig. 3 demonstrates a diagram of an RF downconverter circuit (transmitter of the repeater system) according to an embodiment of the present invention.
• Fig. 4 demonstrates a diagram of an RF upconverter circuit (receiver of the repeater system) with an ISM band antenna for the indoor positioning system according to the present invention.
• Fig. 5 demonstrates a diagram of an RF upconverter circuit according to an embodiment of the present invention.
• Fig. 6 demonstrates a diagram of the triangulation error zone (shown with C) in two-dimensional positioning methods in the art.
• the present invention proposes a GNSS repeater architecture, as well as a method, for indoor positioning marked by remediation via 433 MHz for overcoming the allowable maximum gain problem in global navigation signal regulations while improving the ever-persistent accuracy problem of conventional indoor positioning approaches.
• the proposed 433 MHz- remediating indoor positioning system is readily applicable in established GNSS infrastructures, which makes the solution quickly utilizable and with a low deployment cost.
• GNSS signals are meant to be, as mentioned hereinafter, refer to a general range of satellite navigation signals from 1 to 2.5 GHz. Such range specifically covers those bands of BeiDou; Galileo; GLONASS; GPS and NAVIC that are available for civilian use.
• GNSS signals For indoors, GNSS signals have to go through an additional loss of 10-30 dB, in which case, the RF signal becomes too low for detection by the GNSS receivers and to calculate a position.
• One of the ways to boost the signal level is to use active GNSS signal repeaters. These repeaters will pick up the GNSS signals, amplify and retransmit to where the GNSS signal coverage is desired. However, it is legally prohibited to transmit some GNSS signals above -77 dBm (which is a very low power level RF signal) which requires a special permit from governments.
• the present invention is devised under the recognition that license-free bands of operation are quite suitable for indoor positioning applications since legally allowable levels of signal power at GNSS bands are detrimental to the development of finer systems, especially ones for which robustness, accuracy, precision, and simplicity would be a defining factor.
• one such license-free operation band may be, for example, the ISM band at 433 MHz.
• 433 MHz ISM signal example therefore, confers the invention of a twofold efficiency.
• One of the advantages is that the power level allowable at 433 MHz ISM is 10 dBm, which is 87 dB higher than the GNSS allowed power level, leading to a much larger coverage of signal obtainable indoors.
• the second advantage of the 433 MHz is 11 dB less free space path loss advantage compared to GNSS 1575 MHz signals.
• an advantage 433 MHz ISM when compared to a GNSS frequency e.g. 1575 MHz, is that the signal can penetrate walls and buildings further due to larger wavelength operation. This will also increase the coverage of the indoor area with the 433 MHz signal. The signals will be radiated at 433 MHz indoors, they will not interfere with outdoor GNSS signals.
• GNSS signals are amplified and utilized to track the location of anything carrying a customary receiver indoors.
• ECC Electronic Communications Committee's
• ETSI European Telecommunication Standards Institute's
• EN 302 645 prohibit the overall amplification of GPS signals more than 45 dB, and the antenna gain exceeding 3 dB as it otherwise would affect nearby systems using GNSS services such as aeronautical radio navigation system DME, military and civilian radars, Earth Exploration Satellite Service, and so on.
• GPS repeaters may be used only by the departments of the US Federal Government or those who will deploy the system within a shielded indoor environment or have a license under FCC.
• the proposed system receives GNSS signals originating from different satellites using directional active antennas at different locations and delivers them to the space indoors.
• RF downconverter(repeater) elements including the directional GPS active antennas pick up a different set of satellites depending on their look direction and beamwidths and amplify up to 30 dB for signal conditioning.
• said GNSS signals will then be downconverted to a lower frequency of 433 MHz ISM band.
• Signals once downconverted to 433 MHz ISM band with a downconverter will then be amplified up to 10 dBm power levels as needed.
• an embodiment can wirelessly adjust the gain of the repeaters for different indoor coverage needs by utilizing LNA chains and adjustable digital step attenuators. After filtering for 433 MHz band, the downconverted signals will be transmitted by properly designed 433 MHz antenna. The 433 MHz ISM band signal will subsequently be picked up indoors with a 433 MHz receiver.
• This chain of events is realized by hardware comprising directional GNSS active antennas for picking up a set of satellites, discrete RF downconverter, 433 MHz LNAs, RF filters, adjustable attenuator, 433 MHz antennas, and RF receiver, which is connected to 433 MHz antenna, 433 MHz LNA chains, adjustable digital step attenuator for gain conditioning and an upconverter structures to GNSS band and a GNSS receiver.
• said hardware comprises a GNSS active directional antennas with built-in LNAs, RF downconverter, LNA, digital step attenuator, RF filter at 433 MHz, LNA and 433 MHz antenna on each of three RF downconverter side.
• Said hardware will have RF upconverter side with a GNSS receiver as well as 433 MHz antenna, 433 MHz bandpass filter, 433 MHz LNA, adjustable digital step attenuator, another LNA and a 433 to 1575 MHz upconverter.
• Said GNSS receiver is, in an embodiment, selected from a group comprising GLONASS receivers, BDS receivers, Galileo receivers, and QZSS receivers.
• different embodiments may pertain to upconversion-to and downconversion-from schemes for different GNSS frequencies.
• said system comprises four aspects: Directional active antennas operating in GNSS frequencies; repeaters that comprise LNAs to amplify the signal after downconversion to 433 MHz; receiver RF front-end circuits and a positioning algorithm that processes signals to determine the indoor location of the receiver it operates thereupon.
• Disclosed indoor positioning system utilizes a triangulation-based approach to determine the location of the receiver.
• Disclosed invention predominantly relies on GNSS signals for 2-D (with three repeaters) or 3-D (with 4 repeaters) positioning alike, which are obtained via directional antennas from uninterrupted outdoor positions.
• GNSS signals After said GNSS signals are obtained, they are downconverted to lower frequency ISM band and radiated across the indoor environment in downconverted form via 433 MHz ISM band antenna with amplification and filtering.
• received ISM band signals are upconverted to original GNSS frequencies they are obtained on, forming raw GNSS data to be processed after amplification and filtering.
• the disclosed system treats GNSS satellite signals as if they originate from indoor sources; but unlike the case with pseudolites, synchronization is not a requirement for the transmit sources since they are already in synchronization, and signal content received from satellites are unchanged. Since levels of repeater signals are amplified, sensitive signal reception aspects are not necessary.
• said downconverter side comprises a three-port network to modify DC bias to provide DC power to the active antennas at the directional antennas as shown in Fig. 5.
• said three-port network is a bias tee.
• Said bias tee is followed by a downconverter board, which itself comprises a mixer and oscillator (Wideband Quadrature demodulator in Fig. 5) according to at least one embodiment. Conversion loss of said downconverter board may be in the vicinity of 8.7 dB.
• the low noise amplifier (LNA), preferably having a gain of ⁇ 22.4 dB.
• LNA Low Noise Ratio
• a digital step attenuator which can be adjusted between 0-31.5 dB
• Attenuator is succeeded by another LNA, which is finalized with a bandpass filter preferably having a 20 MHz range and around ⁇ 1.7 dB insertion loss at a definite frequency band.
• said definite frequency band is 433 MHz ISM. All the components listed hitherto may result in an expected downconverter gain including the antennas between 32.9 - 64.4 dB.
• said upconverter side comprises a bandpass filter preferably having a 20 MHz range and around ⁇ 1.7 dB insertion loss at a definite frequency band, which according to at least one embodiment is 433 MHz ISM as shown in Fig. 5.
• Said bandpass filter is followed by an LNA still preferably having a gain of ⁇ 22.4 dB.
• LNA still preferably having a gain of ⁇ 22.4 dB.
• a digital step attenuator with up to 31.5 dB attenuation.
• Attenuator successively connected to yet another LNA, which is itself connected to I+/Q+/I-/Q- power divider and four bias tees.
• Said bias tees are required for biasing upconverter RF inputs.
• the final element in the receiver chain is an upconverter board comprising a mixer and oscillator (Wideband Quadrature modulator in Fig. 5), with a total power loss around ⁇ 1.3 dB. All the components listed hitherto may result in an expected gain between 10.3 - 41.8 dB.
• a multiplicity of GNSS frequency operating directional antennas are disclosed.
• a high-gain, right hand circularly polarized GNSS antenna such as a GPS antenna operating in 1575 MHz LI band is disclosed.
• Said antenna may be an antenna with a beamwidth of 60 degrees.
• GNSS band antennas are also utilized such as the bands of BeiDou; Galileo; GLONASS; GPS those made available for civilian use.
• a GNSS antenna may operate in any GNSS frequency between 1 and 2.5 GHz according to different embodiments.
• repeaters are employed. As demonstrated in the art, repeaters collect satellite navigation signals, amplify them and propagate them within indoor environments where GNSS coverage is limited. This, however, causes less-than-perfect positioning since propagation continues in a non-LoS direction indoors as the distance calculated is different than that of a LoS scenario.
• Known receivers calculate the range as below, and assume it to be the LoS range: where the first term is the distance between the signal source (satellite) and the repeater, and the second term is the distance between the repeater and the receiver. Triangulation algorithms based on this premise produce erroneous positioning estimations. Actual position may be estimated also through pseudoranges as formulated below:
• X sat 9 y Z sat 9 sat stand for satellite coordinates, and; stand for repeater coordinates. In subtracting the distance between the signal source satellite and the repeater, distance between the repeater and receiver is found as demonstrated below:
• a novel location finding algorithm whereby consecutive steps are taken as such: A multiplicity of repeaters collect a multiplicity of different corresponding satellite navigation signals sent by satellites; repeaters propagate ISM -downcon verted satellite navigation signals to the receiver indoors; receiver then upconverts ISM signals to a satellite navigation frequency of GNSS type and solves for the pseudorange of each of said multiplicity of satellites; locates the satellites using satellite ephemeris data; repeater positions are fixed to enable direct computation of the distance between the satellites and repeaters.
• Disclosed novel location finding algorithm advances the state of the art in that, a major accuracy shortcoming regarding triangulation approaches that do not account for clock bias, which creates a 2D triangular region marked as displayed in reference to Fig. 6 within which error margin becomes significantly greater.
• a system for indoor positioning comprising a multiplicity of directional GNSS active antennas collecting satellite navigation signals emitted by a multiplicity of satellites, repeaters for producing secondary signals than said satellite navigation signals and propagating said secondary signals in an indoor environment and at least one receiver capable of receiving and processing said secondary signals to compute location information is proposed.
• said secondary signals for remediation of the location signals are contained in a frequency band lower than GNSS frequencies whereby free path loss is reduced and indoor coverage significantly improved.
• said secondary signals for remediation of the location signals contained in a lower frequency band contain 433 MHz ISM.
• said repeaters are configured to downconvert a GNSS signal to a lower signal such as an ISM band signal at 433 MHz.
• said receiver is configured to upconvert said lower frequency signal to the original GNSS frequency.
• said receiver is further configured such that a clock bias-based pseudorange triangulation is executed to determine location thereof.
• a method for indoor positioning comprises the step of GNSS signals reception, wherein GNSS signals broadcast by satellites are collected by directional active antennas;
• said method comprises the step of downconversion, wherein original GNSS signals are downconverted to a lower- frequency ISM band.
• said method comprises the step of indoor propagation, wherein downconverted ISM band signals are propagated indoors via ISM antennas with lower free space path loss and better penetration
• said method comprises the step of ISM signal reception, wherein ISM signals propagated by repeaters indoor are collected by a receiver;
• said method comprises the step of upconversion, wherein once downconverted ISM signals acquired on receiver end are upconverted to original GNSS band; and,
• said lower-frequency selected for remediation of the GNSS signals in said method is 433 MHz ISM whereby better coverage and greater power transmission.

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• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Position Fixing By Use Of Radio Waves (AREA)

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• 2020
  • 2020-03-13 WO PCT/TR2020/050202 patent/WO2021183067A1/en active Application Filing
  • 2020-03-13 EP EP20727742.7A patent/EP4118459A1/de active Pending

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