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WO1996026579A1 - Nouveau systeme de positionnement cellulaire (cps) - Google Patents

Nouveau systeme de positionnement cellulaire (cps) Download PDF

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Publication number
WO1996026579A1
WO1996026579A1 PCT/US1996/002369 US9602369W WO9626579A1 WO 1996026579 A1 WO1996026579 A1 WO 1996026579A1 US 9602369 W US9602369 W US 9602369W WO 9626579 A1 WO9626579 A1 WO 9626579A1
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WO
WIPO (PCT)
Prior art keywords
navigation
cellular
signal
beacons
signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1996/002369
Other languages
English (en)
Inventor
Leonard Schuchman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nokia of America Corp
Original Assignee
Stanford Telecommunications Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US08/393,312 external-priority patent/US6111538A/en
Application filed by Stanford Telecommunications Inc filed Critical Stanford Telecommunications Inc
Priority to AU54164/96A priority Critical patent/AU5416496A/en
Publication of WO1996026579A1 publication Critical patent/WO1996026579A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/14—Determining absolute distances from a plurality of spaced points of known location
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/20—Instruments for performing navigational calculations
    • G01C21/206—Instruments for performing navigational calculations specially adapted for indoor navigation
    • 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
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
    • G01S1/68—Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
    • 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
    • G01S19/13—Receivers
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • 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
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • G01S19/45—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
    • G01S19/46—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being of a radio-wave signal type
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/0236—Assistance data, e.g. base station almanac
    • 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
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/14—Determining absolute distances from a plurality of spaced points of known location
    • G01S5/145—Using a supplementary range measurement, e.g. based on pseudo-range measurements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
    • H04L27/103—Chirp modulation

Definitions

  • Wireless communications are rapidly augmenting conventional telephone communications. For many types of wireless calls such as 911 or calls for roadside automotive repair/towing, knowing and conveying the location of the call origin is vital. However, since most users of wireless communications are mobile, their location is typically not known and can encompass a large
  • the present invention discloses about how a set of spread spectrum navigation beacons can be uniquely designed and arranged in a cellular pattern, and how the required navigation receiver signal
  • the cellular array of navigation beacons can be a stand-alone navigation system, or it can be co-located and integrated with an existing or future cellular communications system.
  • the object of the invention is to provide a system of spread spectrum navigation beacons arranged geographically in a cellular pattern that supports position determination at a mobile or portable cellular telephone or other wireless communications terminal.
  • the invention features the following:
  • the system of beacons may be a stand-alone system, or an overlay of a cellular communications system in which the beacons occupy the same spectrum as the communications system. 2) In another embodiment, the use of a set of chirped spread spectrum signals to comprise a cellular array of navigation beacons that is used for position location by mobile or portable terminals. Again, the system of beacons may be a stand-alone system, or an overlay of a cellular communication system in which the beacons occupy the same spectrum as the communications system.
  • a unique phase offset in the code relative to the 1 msec epoch can provide a unique signature for a navigation beacon in a local geographical region.
  • Chirped navigation beacons that use a common frequency, but are distinguished by a different phase offsets of the chirp epoch relative to the 1 msec time epoch, and different sweep rates a common frequency band.
  • a unique phase offset in the chirp relative to the 1 msec epoch can provide a unique signature for a navigation beacon in a local geographical region composed of a number of otherwise identical beacons.
  • the "almanac” is comprised of the data needed to convert a set of pseudorange measurements into a position, and includes a list of the cellular broadcast locations and a characterization of the navigation beacons that are
  • NVRAM for the storage of the bulk of the "almanac" data which is unchanging except insofar as the cellular system and/or its navigation beacons are modified as part of system evolution.
  • DSSS Direct Sequence Spread Spectrum
  • CSS Chirped Spread Spectrum
  • FIG. 1 illustrates a mobile terminal taking pseudo-range
  • FIG. 2 illustrates a hexagonal array of base stations covered by three orthogonal navigation beacons (NB) represented by different shades of gray and seven PN codes (or seven phases of a single PN code) which is represented by the numbers (1,2,3...7) in the array,
  • NB orthogonal navigation beacons
  • PN codes or seven phases of a single PN code
  • FIG. 3 illustrates a cellular positioning system of seven
  • NBs navigation beacons
  • FIG. 4A is a general block diagram of a stand alone base station used in this invention.
  • FIG. 4B is a block diagram of a direct sequence spread spectrum
  • FIG. 4C is a block diagram of a chirped spread spectrum (CSS) embodiment base station used in this invention.
  • FIG. 4D is a block diagram of a cellular base station to which the navigation beacon signals of Fig. 4A, 4B and 4C has been added,
  • FIG. 5 is a general block diagram of a cellular position system receiver used in this invention.
  • FIG. 6 is a block diagram of a cellular position system processor with PN navigation signals using a time domain approach,
  • FIG. 7 is a block diagram of a cellular position system processor with PN navigation signals using a frequency domain approach
  • FIG. 8 is a block diagram of a cellular position system processor with chirp signals
  • FIG. 9 is a block diagram illustrating the time-gated approach for frequency notching in a chirp receiver.
  • FIG. 1 shows a mobile user MU surrounded by base stations 10-1, 10-2, 10-3...10-N of a cellular positioning/communications system.
  • the mobile unit MU tracks the navigation signals from at least 3 base stations and measures the pseudorange to each of them by processing their navigation beacons. Measurements from three base stations are required for a 2D solution and if a 3D solution is desired, then measurements from 4 base stations are required.
  • This positioning system is referred to as the Cellular Positioning System (CPS).
  • CPS Cellular Positioning System
  • each cellular base station (BS) broadcasts a spread spectrum navigation beacon (NB) whose frequency and timing are synchronized and slaved to GPS.
  • NB spread spectrum navigation beacon
  • the system of beacons may be a stand-alone system (Fig. 4A), or an overlay of a cellular
  • the beacons occupy the same spectrum as the communications system.
  • the power of the spread spectrum signals described below can be set sufficiently low so as not to interfere with the communications channels, yet sufficiently high to support a good signal for a navigation receiver.
  • Two types of spread spectrum navigation signals are disclosed herein:
  • a GPS-like direct sequence spread spectrum (DSSS) signal in which the navigation beacon is a PN coded broadcast (see FIG.
  • One example code has a length of 1023 and a code period of 1 msec so that the chipping rate of the navigation beacon is 1.023 Mcps. The resulting signal is spread over about 2 MHz of spectrum.
  • the navigation beacon signal may have a different code length and chipping rate, and may support little or no data.
  • navigation beacon is a frequency tone that is repeatedly swept over a chosen frequency band (see FIG. 4C).
  • a 10 MHz band with a period of 1 msec or greater are example parameters for a chirped signal.
  • chirp navigation beacon signals may also incorporate different frequencies, sweep size and sweep rate, and may support little or no data.
  • an efficient set of navigation beacons for a cellular positioning system CPS must conform to a channel structure that supports orthogonal or near orthogonal beacons that do not significantly interfere with each other.
  • the degree of orthogonality is important since within a cellular array of navigation beacons, when a user is near a cellular BS, the navigation beacon signal power from that station may be 30 dB or more stronger than the power of navigation beacon signals from far (i.e., adjacent) BSs. With complete orthogonality, the strong navigation beacon will never interfere with a weak
  • a cellular positioning system CPS In a cellular positioning system CPS, the same channels can typically be reused for beacons over a wide geographic region because range attenuation effectively provides separation between distant beacons that are using the same channel.
  • Current and proposed cellular communications systems use frequency division, time division, code division and data/tone markers to create distinct channels.
  • the DSSS navigation beacons in a cellular positioning system CPS similarly can use frequency, time, code and data to distinguish them from each other.
  • each individual DSSS navigation beacon is characterized by the
  • the chirped spread spectrum CSS navigation beacons in a cellular positioning system CPS similarly can use frequency, time, sweep phase, sweep rate, and data to distinguish them from each other
  • the characterization parameters in a system of chirped navigation beacons are described in Table 2 below. There is much
  • this parameter set can be limited to a subset that fills out the defined cells with navigation beacons with suitable signal characteristics that uniquely define them (in a local region) and solve the near-far interference problem.
  • time_slot and frequency satisfy this requirement. While they do not support complete
  • Table 3A illustrates a sample of DSSS
  • navigation beacon signal sets that satisfy the orthogonality requirements to both solve the near-far interference problem and uniquely identify the navigation beacon in its local environment.
  • the values define 21 distinct navigation beacon signals that are suitable for allocation across a hexagonal array of cells.
  • the hexagonal array is covered by allocating the 3 orthogonal navigation beacon signals over the array (represented by the different shades of gray) and 7 PN codes (or 7 phases of a single PN code) which is represented by the numbers in the cellular array.
  • the 3 different shades can be viewed as either 3 orthogonal time slots or 3 orthogonal frequencies. In this manner a group of 21 cells is formed and is replicated repeatedly to fill any cellular array. Note that in these systems, the separation distance between navigation beacons with the same signal parameters is quite large (roughly 9 cell radii)
  • Table 3B illustrates a sample of CSS navigation beacon signal sets that satisfy the orthogonality requirements for solving the near-far interference problem and for uniquely identifying the beacons in their local environment.
  • A-C 21 distinct navigation beacons are defined, for one system (D),only seven are defined, and for one (E) fourteen are defined.
  • Figure 3 illustrates the allocation of 7 distinct chirp phases (as in System D of Table 2) over a hexagonal array. The seven phases are assigned to seven hexagons of a local cluster, and this pattern is replicated to fill an entire coverage area. In general, it can be shown that in a system of beacons
  • a cellular positioning system CPS can be a stand-alone system, or part of a cellular communications system or a combination of stand-alone stations and cellular sites with a positioning signal.
  • the position is determined at a navigation receiver (NR) by acquiring, tracking and demodulating the navigation beacons.
  • NR navigation receiver
  • all the navigation data required for position determination is broadcast by the navigation beacons.
  • Table 4 An example of the data that would be conveyed by each navigation beacon is illustrated in Table 4. Note that this information conveys the position of the BS as well as the signal parameters of the navigation beacon that is broadcast by that BS .
  • a navigation receiver NR In order to determine position, a navigation receiver NR needs to acquire and measure the pseudorange on at least 3 navigation beacons for a 2D solution (time plus lat/lon), and at least 4 navigation beacons for a 3D solution (time plus lat/lon/alt). In addition, the navigation receiver NR would also have to
  • Step 1 At navigation receiver NR turn-on, the navigation
  • the navigation receiver NR searches the signal parameter space, acquires the first navigation beacon, and measures the pseudorange. The navigation receiver NR then reads the data on the navigation beacon.
  • Step 2 With or without the aid of the data from the first acquired navigation beacon, the navigation receiver NR continues a search for subsequent navigation beacons from other BSs. The navigation receiver NR continues until it makes a pseudorange measurement and acquires the data from at least two additional navigation beacons broadcast from adjacent BSs.
  • Step 3 The navigation receiver NR computes a 2D or 3D position, depending upon the number of navigation beacons acquired and processed.
  • Step 4 The navigation receiver NR continues to acquire and track navigation beacons as the navigation receiver NR may move though the geographic region that is covered by the cellular positioning system CPS, and it periodically recalculates the navigation receiver NR position according to some defined algorithm.
  • the navigation beacons may share the same spectrum as the communications systems (as described in the above-referenced patent application).
  • much or all of the required navigation data may be conveyed by the broadcast control channels of the communications system.
  • each navigation beacon is minimal: at most an 8-16 bit identifier that is unique within the local cellular region.
  • the rest of the navigation data needed is transmitted by the cellular control channels that are broadcast from each cellular BS .
  • the scenario for position determination in this combined communications-navigation system is described below via the operation of a cellular phone and a phone navigation receiver NR.
  • the set of navigation beacon signals illustrated as System A in Table 3A is assumed.
  • Step 1 Comm Initialization via Listening to the Cellular Control Channel: At the start of this scenario, the phone is just turned on. The phone searches for, finds and listens to a cellular communications control channel and initializes itself according to the applicable cellular communications standard or protocol.
  • Step 2 Nav Initialization via Listening to the Cellular Control Channel: In listening to the control channel, the phone also initializes with respect to cellular navigation. When this task is complete, the phone has determined that it is near a specified base station, and has acquired the lat/lon/alt/code_phase/ time_slot for all the base stations in the local environment.
  • This data is conveyed via navigation overhead messages that are broadcast on each control channel; these overhead messages contain a data set as illustrated in Table 4, but also include the data for all of the adjacent cellular BSs as well as an issue number that will change with cell system evolution, and the spectral occupancy of communications channel broadcast by the BS.
  • This information will be stored in non-volatile random access memory (NVRAM) (Fig. 5) so that the data is preserved from call to call.
  • NVRAM non-volatile random access memory
  • NVRAM NVRAM locations of a reasonable sized region of cells can be stored. Every time the phone is in an initialization state, the NVRAM is updated so that the NVRAM always stores the most current
  • the parameters of the local navigation beacons will be known (assuming that the received "issue number" in the navigation data matches the "issue number” of the data stored in NVRAM for that cellular base station). If the received unique ID and issue number do not both match a value stored in NVRAM, then the navigation data would need to be collected before the positioning call could proceed. As the phone explores new territory, the list of cell base station locations would expand to fill the NVRAM. For a phone that covers a great deal of territory, new locations would be written over old locations whenever the capacity of the NVRAM is reached. This navigation data that is stored in the NVRAM is referred to as the navigation almanac.
  • Step 3 Search and Acquisition of a Navigation Beacon (NB): This step can be done in parallel with Step 1 and Step 2. Every cellular base station transmits a navigation beacon with a set of signal parameters designated in the communication broadcast control channel.
  • each navigation beacon is uniquely specified by the phone navigation receiver NR.
  • the phone navigation receiver NR has made a pseudorange measurement on the navigation beacon and has reached synchronization with the navigation system, meaning that it now has an absolute reference for both time_slot and code_phase.
  • each navigation beacon is uniquely specified by the phone navigation receiver NR.
  • the phone navigation receiver NR Having achieved synchronization with code_phase and time_slot of a navigation signal in Step 3, the phone navigation receiver NR looks up (in the NVRAM) the code_phase and time_slot of other navigation beacons in the local environment; the phone navigation receiver NR then proceeds to acquire these signals and make pseudorange measurements. Note that since code_phase and time_slot of a navigation signal in Step 3, the phone navigation receiver NR looks up (in the NVRAM) the code_phase and time_slot of other navigation beacons in the local environment; the phone navigation receiver NR then proceeds to acquire these signals and make pseudorange measurements. Note that since code_phase and
  • time_slot uniquely specify the navigation beacon in its local environment, the data on these navigation beacons is not read. Note also that acquisition of navigation beacons in this Step may be aided by using the data on the spectral occupancy of
  • the phone navigation receiver NR can proceed to Step 5.
  • Step 5 Calculation of Position: With a total of 3 or more pseudorange measurements, the navigation receiver NR can generate a 2D solution, solving for navigation receiver NR time and location (lat/lon). With a total of 4 or more psuedorange measurements, the navigation receiver NR can generate a 3D solution, solving for time and location (lat/Ion/alt). Excess measurements can be used to generate added measurement precision and robustness via standard techniques for minimization of measurement variance and elimination of out of bounds
  • Step 5 the phone displays a “position fixing” indicator analogous to the roaming indicator
  • the "position fixing” indicator will tell the user that the phone knows its position at that particular moment in time.
  • Step 6 Recalculation of Position: In the idle state, the phone will continue to listen to the communications control channel. During this time, the phone navigation receiver NR may or may not (e.g., where power is scarce) continue to operate. In general, the phone navigation receiver NR will recalculate its position according to a programmed algorithm. Recalculation could be done continuously, or in response to an expired time or event as described below:
  • Step 3 the phone displays a position fixing indicator that tells the phone user that the phone is ready and prepared to make a "position
  • PE enhanced enhanced
  • Step 1 Initiating the Call: The phone user initiates a PE phone call in the same manner as normal calls (nominally by dialing the number and pressing the Send key). Depending upon the way positioning service is used, the phone user may convey a desire for a PE call via the pressing of some specified key combination. For 911 calls, a PE call would be the default.
  • Step 2 Phone Response: In response to the user call initiation, the phone seizes the access control channel and sends a digital message in accordance with cellular system specifications. This message contains the phone electronic serial number (ESN), the user mobile phone number (MIN), and other such data. In a PE phone call, the digital message would contain an additional cellular control word that conveys the lat/lon of the phone location in accordance with a standard compressed format. For example, to convey the lat/lon of the phone (with a 10 meter quantization) relative to the lat/lon of the base station would require about 24 bits.
  • ESN phone electronic serial number
  • MIN user mobile phone number
  • the digital message would contain an additional cellular control word that conveys the lat/lon of the phone location in accordance with a standard compressed format. For example, to convey the lat/lon of the phone (with a 10 meter quantization) relative to the lat/lon of the base station would require about 24 bits.
  • Step 3 MTSO Response.
  • the MTSO has the location of the phone prior to call setup, and can therefore use this information in call processing.
  • the MTSO could use location knowledge to find the appropriate emergency service center for the phone location, and then route the call and the location data to that emergency service center.
  • the MTSO would also send the location of the calling phone to the call destination. This can be accomplished in-band via modem (in accordance with a established standard) or out-of-band via SS7.
  • Step 4 Call servicing: Call servicing of a "one-shot'
  • the MTSO assigns an
  • the phone then switches to that channel while the MTSO proceeds to patch the call through to the dialed number.
  • Step 5 Call Servicing for "Continuous" Position Fixing:
  • the phone navigation receiver NR must continue to receive and monitor a control channel, since the ability to position fix depends upon the navigation overhead data that is broadcast on the control channels.
  • the phone must continue to monitor control channels and switch to a stronger one as required in order to maintain a current file of the navigation data.
  • the phone navigation receiver NR continues to calculate its position.
  • Each position update may then be periodically sent to the MTSO via a specially-defined message on the voice control channel.
  • the message can be sent in-band via a simultaneous "data-in-voice" modem.
  • the continuous monitoring of a control channel after switching to a voice channel is a departure from normal cellular telephony operations but it is not inconsistent with such operations, and may even provide telephony benefits. For example, if the cellular telephone continues to monitor a control channel, the MTSO has a means to offer such services as "call waiting" by alerting a phone via the control channel that a call is being placed to their busy number.
  • FIG. 5 A overview of receiver processing, within the user's unit, is show in Figure 5. Note that the user's unit may be a cellular car phone, portable phone, or other receiving device that may, for example, operate in a general PCS environment. As seen in
  • the composite incoming RF signal is received by a single antenna (AN) and is amplified and conditioned by a single RF front end (RFE) (e.g., Low Noise Amplifier).
  • RFE RF front end
  • the composite incoming signal typically spans tens of MHz (e.g., > 20 MHz for cellular).
  • a common antenna AN and RF front end RFE is applicable for both communications and navigation is a unique and novel feature of this invention.
  • the signal output of the RF front end RFE is downconverted via mixer MX, and a single fixed
  • the IF signal is filtered by Bandpass Filter BPF, whose bandwidth is approximately 2 Mhz, to
  • the Cellular Positioning System CPS Processor which is amenable to a miniaturized/low-power implementation, executes all the required signal processing functions on the chirped or PN spread-spectrum signals of interest, to enable highly accurate navigation.
  • the outputs of the CPSP block are the relative PN code or chirp timing epochs of each of the cellular base station BS spread-spectrum signals being tracked; as discussed earlier, up to seven such signals may be tracked for a typical hexagonal cellular configuration. Also, as discussed in earlier sections a minimum of three "high quality" signals must be tracked to enable a highly accurate 2D navigation solution. As such, considerable diversity and robustness is built into this
  • the timing and other data output from the CPSP is fed into the Navigation Processor block NP, which converts the relative timing information from CPSP into actual user position (e.g., latitude/longitude).
  • CPSP block While several embodiments of the CPSP block may exist, two unique embodiments for DSSS navigation beacons are illustrated in
  • the heart of the CPSP in Figure 6 is the serial combination of the two Charge Coupled Device (CCD) blocks shown.
  • CCD Charge Coupled Device
  • the processing shown here is a unique application and extension of the IF sampled CCD demodulation described in the above-referenced patent and another patent application that is currently pending. The key features of this processing are as follows:
  • the IF is sampled at a carefully selected rate, so that successive samples effectively represent in-phase and quadrature baseband components.
  • This sampling rate is (4/k) ⁇ the IF, where k is an odd integer.
  • baseband components are generated here without the need for mixer components.
  • these operations are performed at high speed and low power consumption without A/D conversion, since the CCD is an analog device.
  • a single A/D converter is
  • the first CCD is implemented as a programmable transversal filter, CTF, whose tap weights may be programmed with multi-bit (e.g., 8) quantization, to enable shaped filtering.
  • CTF programmable transversal filter
  • the specific CTF of interest "notches" out the high-power, narrowband communication signals that may degrade spread-spectrum signal demodulation.
  • the CCD following the transversal filter is used to acquire and track the desired spread-spectrum signal this CCD is discussed further below.
  • the CTF is always bypassed for QCDMA, since notching is never needed when operating in the QCDMA spread-spectrum environment.
  • the AMPS or TDMA CC provides the CPSP with the frequencies of the communication channels employed by the BS in the user's cell. Once this data is received by the CPSP, it programs the taps of the CTF to "notch" out these "strong” narrowband signals, thereby virtually eliminating the "near-far” problem. This notching remains in place as navigation processing is in progress.
  • the CTF tap weights are appropriately adjusted based on data provided by the new CC designated to the user's new cell BS.
  • the CTF is followed by another CCD, CCF, that is sampled at the same rate as the CTF.
  • CCD, CCF has fixed tap weights matched to the PN code of interest, and provides the extremely rapid PN code acquisition that is essential for applications such as 911.
  • the uniqueness of this implementation is noted. Specifically, for the Table 3A System A of interest, a single CCD PN matched filter correlator is all that is needed to process all CPS spread spectrum signals across the entire cellular system. This is because the same PN code is transmitted by all cell BSs, with discrimination among sites being executed via the combination of the time diversity and code phase diversity described in Sections 3 and 4.
  • the CCD, CCF output is A/D converted, to enable efficient post-processing as shown.
  • the A/D operation is advantageous here since the CCD output SNR is much higher than at the input.
  • CCD technology has advanced to the point where an ultra-low power A/D may be directly incorporated onto the CCD chip itself, wherein the A/D is implemented using "charge-domain" processing techniques.
  • the A/D output is averaged and algorithmically processed to determine the PN code correlation peaks ⁇ hence, their relative timings ⁇ thereby yielding the desired timing data for transfer to the Navigation Processor.
  • the algorithmic processing of the Digital Processor, DP further provides AFC frequency control corrections, as necessary, to compensate for offsets in the user's local oscillator. These frequency corrections are executed by suitable adjustment of the CCD IF sampling rate ⁇ another unique feature of this
  • the procedure at service turn-on is virtually identical to the time domain approach, in that the CC of the user's BS is first processed to identify the spectral locations of the "strong" communication channels associated with the user's BS.
  • each block of 4 ⁇ 1023 samples encompasses the full PN code cycle.
  • the collected samples are then used to generate the associated FFT (zero padding may also be used, as necessary or desired for additional resolution).
  • the result of the multiplication is processed by an inverse FFT (IFFT) to yield the time-domain correlation function.
  • IFFT inverse FFT
  • the IFFT may further be processed to yield frequency correction information, to correct for local oscillator offset, and the result fed back to the Complex Multiply block shown, CM.
  • the CSS beacons are assumed to have a period of 5 msec during which they sweep over 10 MHz of frequency.
  • the key features of the signal processing are as follows:
  • the signals enter at RF and are mixed with the output of a synthesizer SYN.
  • the synthesizer SYN produces a frequency staircase at 10 KHz steps (each lasting 5 ⁇ sec). Thus, in 5 msec (1000 stairs), the synthesizer moves over 10 MHz of frequency.
  • the nominal intermediate frequency (IF) resulting from the mixing process is 70 MHz.
  • IF intermediate frequency
  • the navigation receiver conducts a search to first acquire a strong navigation signal. The process by which this is done is a "largest of" detection algorithm based upon a search over all phases of chirp. This process of acquisition and tracking of the first signal is described in items 2 and 3 below. The acquisition and tracking of subsequent navigation beacons is described in item 4 below.
  • the output of the mixing process due to a received chirped navigation beacon is a series of short chirps each with a duration of 5 ⁇ sec. If the synthesizer is roughly in phase with the navigation signal, the chirps will be within 10 KHz of the 70 MHz IF. If the synthesizer is out of phase with the incoming chirped signal, the chirps after the mixing process can be up to ⁇ MHz offset from the 70 MHz IF.
  • the CCD sampling rate is 20 MHz and the CCD has fixed binary tap weights so that alternate output samples of the CCD are a moving sum of the in-phase (I) and quadrature (Q) components of the input signal.
  • the moving sum over 5 ⁇ sec is essentially a low-pass filter with a first null out at 200 KHz.
  • the output of the CCD is then sampled by the A/D stage of the receiver at 5 ⁇ sec intervals (after each frequency stair).
  • the sampling rate of the A/D for I/Q pairs is 200 KHz, and further processing by the navigation receiver is all digital.
  • the signal is further
  • the filter bandwidth of the receiver has been collapsed down to 10 KHz to the first null.
  • the maximum allowable time for coherent accumulation is controlled by the drift in the local oscillator (that is driving the synthesizer) relative to the incoming received navigation signal. If the local oscillator (LO) is accurate to +1 part in a million, the relative frequency drift for a 900 MHz navigation signal will be about ⁇ 900 Hz. Over 0.1 msec, a 900 Hz offset will result in about a 30° drift in the phase of the I and Q samples. For drifts larger than this, cancellation among the accumulated samples will occur.
  • This value is then dumped and stored in memory. This value stores the detection statistic for a search of an incoming chirp signal with a bandwidth that is roughly within 5 KHz of the chirp that is generated by the synthesizer.
  • the control of the synthesizer is turned over to a tracking loop.
  • the CCD output is a series of I/Q pairs at a 200 KHz rate.
  • the DSP then implements an accumulator over a time interval of from 1 msec to 10 msec which corresponds to a tracking bandwidth of 1000 Hz and 100 Hz, respectively.
  • the tracking accurate ( ⁇ x) is dependent upon the resolution of the frequency tracking bandwidth and is governed by the following formula:
  • a 100 Hz resolution corresponds to a 15 meter accuracy for the pseudorange tracking measurement.
  • multipath delays of up 1 ⁇ sec (300 meters) can be expected; thus, at times this will create a broadening of the frequency on the order of 1000 Hz.
  • the parallel receiving channel in Figure 8 begins operation.
  • the acquisition and tracking for subsequent navigation signals is similar to that of the first navigation signal, but there are some significant differences. Firstly, with the acquisition of a first navigation signal,the search space for the chirp phase is reduced by about a factor of 10 so that subsequent acquisitions are accomplished in about 1 second. In addition, there is a reasonable chance that the subsequent navigation signals will be interfered with by strong narrowband communications signals from a nearby cell site. In this case, this interference must be mitigated by a time-gated switch that eliminates this
  • the synthesizer passes through the occupied narrowband communications channels.
  • the communications channels can be attenuated by 40 dB or more, and allow the reception of much weaker navigation signals from more distant cell site.
  • a sliding window of FIR filter is
  • narrowband interferer from wideband filter WF are correlated in correlator COR with signals from chirp generator CG (with
  • a set of direct sequence spread spectrum signals (with properties described by time slot of operation, specific PN code, PN code phase, and carrier frequency) to comprise a cellular array of navigation beacons that is used for position location by mobile or portable terminals.
  • the system of beacons may be a stand-alone system, or an overlay of a cellular communications system in which the beacons occupy the same spectrum as the communications system.
  • a set of chirped spread spectrum signals to comprise a cellular array of navigation beacons that is used for position location by mobile or portable terminals.
  • the system of beacons may be a stand-alone system, or an overlay of a cellular communication system in which the beacons occupy the same
  • navigation beacons that use a common frequency and a common PN code, but are distinguished by a different phase offset of the PN code epoch relative to the 1 msec time epoch.
  • a unique phase offset in the code relative to the 1 msec time epoch can provide a unique signature for a navigation beacon in a local geographical region.
  • a unique phase offset in the chirp relative to the 1 msec time epoch can provide a unique signature for a navigation beacon in a local geographical region composed of a number of otherwise identical beacons.
  • the "almanac” is comprised of the data needed to convert a set of pseudorange measurements into a position, and includes a list of the cellular broadcast locations and a
  • NVRAM non-reliable and low-latency memory
  • NVRAM non-reliable and low-latency memory
  • DSSS or chirped spread spectrum CSS navigation beacons that are uniquely characterized in a local region by their assigned signal characteristics so that data modulation of the beacons is not required for beacon identification.
  • spectrum CSS navigation receiver to filter out the interference caused by the occupied narrow band communications channels of a cellular communications system.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Automation & Control Theory (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Système de positionnement permettant de localiser un corps mobile, conprenant plusieurs stations (Figs. 4A, 4B) d'émissions terrestres à étalement du spectre, ces stations étant agencées géographiquement selon une configuration cellulaire (Figs. 2, 3). Chaque station d'émissions comprend un modulateur (22, 25) fournissant une structure de signal de canal qui est sensiblement octhogonale par rapport aux stations adjacentes de la configuration cellulaire, chaque signal de canal comprenant des données de balise de navigation ayant une identification de balise unique, une latitude et une longitude de la station, des caractéristiques de phase et de tranche de temps et des paramètres sélectionnés des stations adjacentes. Dans un mode de réalisation, chaque modulateur (25) fournit un signal à fréquences modulées et à étalement du spectre où la balise de navigation est une tonalité de fréquences qui est balayée de manière répétée sur une bande de fréquences sélectionnées pour chaque station. Dans un autre mode de réalisation, chaque modulateur (22) fournit un signal à étalement du spectre à séquence directe semblable au système de positionnement global dans lequel la balise de navigation est un signal d'émission à codage PN. Un récepteur (Fig. 5) sur le corps mobile reçoit les signaux à étalement du spectre provenant d'au moins trois stations d'émissions à étalement du spectre et détermine son emplacement. Une quatrième station d'émissions à étalement du spectre fournit l'altitude. Des signaux satellites CPS peuvent être utilisés pour contrôler la synchronisation.
PCT/US1996/002369 1995-02-23 1996-02-23 Nouveau systeme de positionnement cellulaire (cps) Ceased WO1996026579A1 (fr)

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AU54164/96A AU5416496A (en) 1995-02-23 1996-02-23 Novel cellular positioning system (cps)

Applications Claiming Priority (2)

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US08/393,312 1995-02-23
US08/393,312 US6111538A (en) 1994-12-23 1995-02-23 Cellular positioning system (CPS)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2326550A (en) * 1997-06-10 1998-12-23 Texas Instruments Ltd Guidance system
WO1999026370A3 (fr) * 1997-11-14 1999-07-22 Univ Edinburgh Terminal de communications et son procede de fonctionnement
GB2491890A (en) * 2011-06-17 2012-12-19 Cambridge Silicon Radio A receiver for chirp modulation signals applies coherent and non-coherent integrations with adaptable integration parameters
CN106160784A (zh) * 2015-03-03 2016-11-23 商升特公司 蜂窝频带中的通信设备和方法
US10841892B2 (en) 2003-06-27 2020-11-17 Qualcomm Incorporated Local area network assisted positioning

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5379320A (en) * 1993-03-11 1995-01-03 Southern California Edison Company Hitless ultra small aperture terminal satellite communication network
US5420592A (en) * 1993-04-05 1995-05-30 Radix Technologies, Inc. Separated GPS sensor and processing system for remote GPS sensing and centralized ground station processing for remote mobile position and velocity determinations

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5379320A (en) * 1993-03-11 1995-01-03 Southern California Edison Company Hitless ultra small aperture terminal satellite communication network
US5420592A (en) * 1993-04-05 1995-05-30 Radix Technologies, Inc. Separated GPS sensor and processing system for remote GPS sensing and centralized ground station processing for remote mobile position and velocity determinations

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2326550A (en) * 1997-06-10 1998-12-23 Texas Instruments Ltd Guidance system
GB2326550B (en) * 1997-06-10 2002-01-23 Texas Instruments Ltd A navigational system
WO1999026370A3 (fr) * 1997-11-14 1999-07-22 Univ Edinburgh Terminal de communications et son procede de fonctionnement
US6898176B1 (en) 1997-11-14 2005-05-24 The University Court Of The University Of Edinburgh Communications terminal and operating method
US10849092B2 (en) 2003-06-27 2020-11-24 Qualcomm Incorporated Local area network assisted positioning
US10841892B2 (en) 2003-06-27 2020-11-17 Qualcomm Incorporated Local area network assisted positioning
GB2491890B (en) * 2011-06-17 2017-12-27 Qualcomm Technologies Int Ltd Chirp communications
US8817843B2 (en) 2011-06-17 2014-08-26 Cambridge Silicon Radio Limited Chirp communications
GB2491890A (en) * 2011-06-17 2012-12-19 Cambridge Silicon Radio A receiver for chirp modulation signals applies coherent and non-coherent integrations with adaptable integration parameters
EP3208946A1 (fr) * 2015-03-03 2017-08-23 Semtech Corporation Procédé et dispositif de communication dans la bande cellulaire
US9800288B2 (en) 2015-03-03 2017-10-24 Semtech Corporation Communication device and method in the cellular band
CN106160784A (zh) * 2015-03-03 2016-11-23 商升特公司 蜂窝频带中的通信设备和方法
US10148313B2 (en) 2015-03-03 2018-12-04 Semtech Corporation Communication device and method in the cellular band

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