RU2351943C2 - Method and device for optimisation of location detection based on gps in presence of time-variable frequency error - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: suggested method for optimisation of location detection based on GPS in presence of time-variable frequency error, consists in the fact that resulting Doppler shift of GPS and Doppler shift or CDMA code are continuously measured and/or calculated, and then their negative effects are minimised at detection of location by means of GPS Doppler search windows recentering on the basis of GPS Doppler shift value, and also application of GPS Doppler shift value and CDMA code Doppler shift for correct distribution for measurements of pseudodistance in GPS and AFLT measurements of control phase, accordingly, for the total time prior to their application in mechanism for location detection.

EFFECT: improved accuracy of location detection for mobile station or wireless communication device.

10 cl, 3 dwg

Description

The priority of this application is stated based on the filing date of provisional application for US patent No. 60/420583 dated October 22, 2002 and provisional application for US patent No. 60/440960 dated January 16, 2003.

FIELD OF THE INVENTION

The present invention relates generally to communication systems and, more particularly, to systems and methods for determining the location of a wireless communication device in a code division multiple access communication system.

State of the art

Mobile communication systems offer increasingly advanced capabilities for locating a mobile network terminal. Legislative requirements may require the network operator to report the location of the mobile terminal when it sends a call to an emergency service, such as 911 in the United States. In a digital cellular network of a Code Division Multiple Access (CDMA) multiple access system, positioning can be provided using an advanced forward link triangulation (AFLT) technique, whereby the location of a mobile station (MS) is calculated from the time of arrival of the radio signals from the mobile station base stations (BS). An even more advanced method is hybrid positioning, in which the mobile station uses a Global Positioning System (GPS) receiver and its location is calculated from both AFLT and GPS measurements. In another application of this hybrid method, time obtained from a cellular network synchronized with GPS is used to obtain GPS measurements and calculate the location of the mobile station.

GPS receivers are integrated into modern mobile terminals to increase the accuracy of determining the location of the mobile terminal. GPS receivers can be autonomous (autonomous) and perform all the functions of GPS capture and location calculation, or they can be autonomous (with radio support) and operate on the basis of a cellular network to provide GPS capture data and, possibly, perform location calculations. When receiving GPS assistance data from a network, a GPS-capable mobile terminal can receive time and position data from GPS satellites in about 10 seconds or less during a normal telephone call. Many, if not most, GPS CDMA cordless phones are supposed to be radio-supported GPS receivers with the hybrid ability to provide GPS and AFLT location information after requesting a serving base station that processes a call from the cordless phone. The location session may be performed using the MS or in the MS itself, depending on where the location is being calculated. In the case of determination by the MS, the mobile station sends the raw or pre-processed measurement data back to the base station. Then the network node calculates the location. In case of determination in the MS, the location calculation is performed in the mobile station.

The protocols and message formats for locating CDMA using AFLT, GPS and hybrid receivers, applicable both to the determination by the MS and the MS itself, were published in the TIA / EIA IS-801-1 2001 standard entitled "Service Standard positioning for dual-mode spread spectrum systems. "

In another method, measurements for determining location are performed by a network node, rather than a mobile station. An example of such network techniques is the RTD measurement performed by serving base stations. The measurements performed by the mobile station can be combined with network measurements to increase the availability and accuracy of location calculations.

Disclosure of invention

Large GPS Doppler shifts can adversely affect the accuracy of determining the location of a mobile station or wireless communication device, and this, in turn, can affect GPS Doppler estimates and GPS Doppler measurements performed by the wireless communication device. The quality of Doppler GPS measurements is very important for determining the location, since poor-quality measurements can impede the capture of satellites by wireless communication devices in the most sensitive modes with a narrow frequency range, and this reduces the effectiveness of GPS measurements. The large unaccounted for Doppler shift in GPS measurements also negatively affects the accuracy of positioning due to the negative effect on the propagation time of GPS code phase measurements over the total time. This effect is the most serious problem with large search windows. In addition, the poor quality of Doppler measurements also directly affects the speed estimation of a wireless communication device.

Microphone developers can also use PLL systems deliberately executed with static errors in the output frequency. In addition, these static frequency shifts may be different depending on the output frequency of the PLL system. Although such CDMA channel frequency offsets may not affect CDMA performance, they will have the same effect on GPS performance as the GPS Doppler shift described above. In addition, they further reduce the accuracy of positioning due to the negative impact on the spread of AFLT measurements of the code phase at normal times before they are used in the positioning mechanism.

Given these problems, according to a basic aspect of the present invention, there is provided a method for determining the center of a search window for searching for a GPS satellite, comprising continuously measuring and / or calculating a GPS Doppler shift, and then minimizing the negative effects of GPS Doppler shift with respect to positioning by centering and Re-centering Doppler GPS search windows based on GPS Doppler shift.

According to another aspect of the present invention, there is provided a method for taking into account the GPS Doppler shift during the propagation of the GPS code phase measurement time to the total time until the code phase measurements are reported to the location unit (PTO) in the pseudo-distance measurement (IPR) message, or before using GPS measurements in the calculation determine the location in the wireless device.

According to another aspect of the present invention, there is provided a method for accounting for the residual Doppler shift of a CDMA code during the distribution of AFLT code phase measurements by the total time until the code phase measurements are reported to the position determination unit (PTO) in the control phase measurement (ICF) message and / or before using AFLT measurements in a proprietary mechanism for determining the location of a wireless device.

Satellite capture in the most sensitive mode with a narrow frequency range is achieved by re-centering the GPS Doppler search window based on GPS Doppler shift values. Improving the accuracy of positioning is achieved by taking into account the corresponding values of the Doppler shift during the propagation of GPS and AFLT time measurements of the code phase for the total time. These improvements provide increased efficiency of pseudo-distance measurements and location accuracy in the proposed tracking and location system of a wireless communication device.

Brief Description of the Drawings

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which like elements are denoted by like reference numerals and in which

figure 1 illustrates the extension of the measurement time of the code phase to one GPS visit,

Fig. 2a illustrates the propagation of GPS code phase measurement time back to a plurality of GPS visits, and

2b illustrates the forward propagation of GPS code phase measurement time to a plurality of GPS visits.

The implementation of the invention

Hereinafter, a new improved method and apparatus for performing position determination in a wireless communication system will be described. An exemplary embodiment will be described in the context of a digital cellular telephone system. Although use in this context is preferred, other embodiments of the invention may be employed in various conditions or configurations.

Typically, a GPS constellation consists of 24 satellites: 21 spacecraft (SC) used for navigation, and 3 spare. Each spacecraft has a clock that is synchronized with GPS time by monitoring ground stations. To determine the position in time, the GPS receiver processes the signals received from several satellites. At least four satellites must be used to solve 4 unknowns, such as X, Y, Z, and time. However, it should be understood that the invention is not limited to the use of any particular type of global satellite system to assist in positioning.

Typically, to implement the present invention with any type of wireless communication system, such as a TDMA cellular telephone network, it is advisable to refer to industry standards for descriptions regarding compatible location services. For example, the following detailed description relates to TIA / EIA IS-801-1 2001, Standard for Location Services for Dual Mode Spread Spectrum Systems, which is particularly suitable for CDMA networks using AFLT and GPS. The TIA / EIA ANSI-136 standard (Positioning of a mobile communication system using a system via satellites) is adapted to TDMA digital PCS systems in the USA. The standards of the third-generation cooperation project 3GPP TS 04.31 and TS 25.331 for Location Services (LCS) (UE positioning using OTDOA) are adapted to the European GSM wireless telecommunication networks.

Two reasons have been identified that are likely to cause shifts in GPS Doppler measurements independent of the CDMA channel. One reason is the temperature-induced drift of the output frequency of the voltage-controlled and temperature-controlled generator (UNUTG) due to the power amplifier (UM) turning off during switching from CDMA to GPS. Another reason is the shifts of the control voltage Vdd (TRK_LO_ADJ) of the UNUTG in steady state, which are most likely caused by changes in the load currents.

Wireless telecommunication networks use frequency control loops in wireless devices or mobile stations to track any carrier frequency shifts. This eliminates the problem of any drift in the frequency of the UNUTH or shifts in the control voltage (TRK_LO_ADJ) of the UNUTG. Although this is true when the wireless devices are in CDMA mode, this is not necessarily true when the wireless device is in GPS mode. When working with radio control, the frequency control loop is disabled during GPS processing, since the wireless device is constantly in capture mode. This means that the UNUTG works out of sync when the receiver tunes out of the CDMA range and while it processes GPS signals. Therefore, the arising drift at the local oscillators or any shifts of the TRK_LO_ADJ Vdd will directly affect the Doppler estimation of GPS. In battery life, the device demodulates the GPS signal, and although it becomes possible to monitor the frequency, it is not guaranteed for all operating conditions. In the absence of frequency tracking, the UNUTG will again work out of sync and the resulting temperature drift and TRK_LO_ADJ shifts will again affect the GPS Doppler estimate.

In order to reduce the temperature-induced systematic drift of the UNUTG, the manufacturers of UNUTG are required to increase the maximum temperature stability of the UNUTG, and the manufacturers of wireless devices must solve structural problems in order to reduce the temperature gradients at the UNUTG. Examples of solving structural problems can be placing the PM as far away as possible from the UNUTG, including insulating means in the housing of the wireless device, and adding insulating material to or around the UNUTG. Nevertheless, the maximum slope of the temperature stability of the UNUTG is becoming more and more, given the industry trend towards a decrease in the size of the UNUTG, therefore, it is required to use digital UNUTG with digital temperature compensation. Another industry trend is the development of wireless devices with smaller form factors, which makes the design solutions mentioned above ineffective for reducing temperature gradients at UNUTG.

In addition, it is not clear whether any commercially available controller will be able to reduce the shifts of the control voltage Vdd of the UNUTH due to changes in the load currents. Thus, the proposed correction scheme for the GPS Doppler shift independent of the CDMA channel is an effective and realistic means for continuously measuring the GPS Doppler shift independent of the CDMA channel and reduce its negative effects by centering or re-centering the GPS Doppler search windows, respectively, and also taking into account the Doppler shift of GPS during the propagation of GPS measurements to the total time.

It is known that some designers of wireless devices can use PLL systems specially designed with static errors of the output frequency. Although these CDMA channel-dependent shifts may not affect CDMA operation, they will transform into a CDMA channel-dependent Doppler GPS shift with the same effect on GPS characteristics as the CDMA channel-independent Doppler shift described above, and therefore they cannot neglected. In addition, they will further degrade the accuracy of the positioning due to the negative influence on the spread of AFLT code phase measurements on the total time before they are used in the positioning mechanism.

More specifically, in CDMA mode, these frequency errors will be monitored by frequency control loops using the appropriate correction to TRK_LO_ADJ and using time control loops to track the resulting Doppler shift of the CDMA code for CDMA demodulation. However, modern AFLT search does not include time control, which leads to a Doppler error in the CDMA code in AFLT measurements in the presence of such deliberately introduced shifts depending on the frequency of the CDMA. In addition, in GPS mode, the frequency control loops are open and TRK_LO_ADJ is frozen at its CDMA values, and this situation is the opposite of the intentionally introduced CDMA frequency error mentioned above. Therefore, this error also translates into a GPS Doppler shift dependent on the CDMA channel in GPS pseudo-distance measurements. Thus, both GPS measurements of pseudo-distance and AFLT measurements of the control phase will have corresponding manifestations of the Doppler shift dependent on the CDMA channel, which cannot be adjusted in modern wireless device configurations or the Doppler shift correction scheme independent of the CDMA channel.

Therefore, such a specific Doppler shift is called a CDMA channel dependent Doppler shift and can be calculated by software based on the UHF LO PLL frequency and the divisor coefficient for this CDMA channel. In this case, the software-dependent CDMA-dependent Doppler shift can be used together with the CDMA channel-independent Doppler shift, as discussed above, to re-center the Doppler GPS search windows and extend both GPS and AFLT to code phase measurements, as will be described below.

Thus, according to the present invention, the CDMA measurement Doppler shift correction circuit consists in continuously measuring and / or calculating an independent and / or CDMA channel dependent Doppler shift, then GPS Doppler search windows are accordingly re-centered and this shift taken into account during GPS, and in the case of a CDMA channel-dependent Doppler shift also during the spread of the AFLT time, the code phase measurements are taken over the total time. Also, the total GPS Doppler shift is subtracted from the measured GPS Doppler shift before transmitting it in the IS-801.1 IPR message to the PTO for the mode using the MS, or before using the wireless device for determining the location and / or speed in the wireless device for the detection mode in the MS or offline mode .

The measured CDMA channel-independent Doppler shift is stored in the non-volatile (EH) memory of the wireless device as an EH element, called E_DOPLER_SHIFT. The calculated CDMA channel-dependent Doppler shift is normalized by the frequency of the CDMA channel and then stored in the volatile memory of the wireless device as a variable DMSS_DOPLER_SHIFT, which will then be used together with the EN element DENSULER_SHIFT to re-center the windows of the Doppler GPS search for all GPS search modes, as well as the correct propagation and AFLT measurements of the code phase for the total time until they are used in the calculation of the location. This re-centering of the GPS Doppler search windows and spreading the code phase measurements over the total time using the DMSS_DOPLER_Shift takes into account the CDMA channel-dependent part of the GPS Doppler shift, allowing the EL element to retain the GPS-independent part of the CDMA channel Doppler shift.

According to the present invention, the loops of the CDMA channel-independent Doppler shift correction circuit include an open correction loop and a closed correction loop. An open correction loop includes calibrating the GPS Doppler shift of the wireless device and storing it in the non-volatile memory of the wireless device as an element called an EN_DOPLER_SHIFT. A closed correction loop includes the use of a filtered version of SYNCHRO_DRAEF, if available, and if the wireless device is stationary (i.e., according to one embodiment, its speed does not exceed ten kilometers per hour), weighted by uncertainty of location to update the element’s EH. SYNCHRO_DRAFT, location uncertainty and speed information are supplied to the wireless device in response to the UOM and call flows when determined by the MS, or can be similarly calculated in the wireless device itself if determined in the MS or autonomous case. SYNCHRODRAFT is computed based on at least four GPS measurements. Another version of the closed correction loop is a filtered version of the average Doppler shift for all valid reported measurements, which can be weighed by the measured C / N. It can also be used to update the element’s electric power if SYNCHRO_DRAEF is not available, and if more than a certain number of valid satellites are detected, and the wireless device is stationary, for example, its estimated speed does not exceed ten kilometers per hour. According to the invention, the GPS Doppler shift of the pseudo-distance measurements is the difference between the measured Doppler shift and the common Doppler shift estimated for a particular satellite or UOM in the call flows when determined by the MS (transmitted to the wireless device in the Capture Assistance message) or by the wireless device itself in case definition in the PS and in the autonomous case. Then determine the average for all valid measurements. Valid measurements are the best measurements that have passed tests for false alarm, noise, interference, cross-correlation, and some other tests to filter out bad measurements.

Filtering is carried out through an IIR filter of the following form y (n) = (1-b) * y (n-1) + a * x (n), where a is programmable, y (n) is the new value, y (n- 1) is the old value of the EH of the Doppler shift element, and x (n) is the weighted SYNCHRO_DREIF, in this case b = 0, or the average Doppler shift of all reported measurements, as discussed above, in this case b = a. It should be noted that a check is applied to instantly change x (n), namely, if x (n) becomes larger than some predefined value Ho, then the element will be updated with Ho, where the value of Ho is optimized and different for capture and tracking modes .

The proposed method for correcting the Doppler shift of a GPS independent of the CDMA channel has two different modes, namely, a capture mode and a tracking mode. The capture mode is used to speed up the fitting of the GPS Doppler shift element independent of the CDMA channel to the value of a separate wireless device during the initial use of the GPS wireless device. The capture mode uses a shorter capture time constant for the IIR, and Doppler search windows can be re-centered for the most sensitive modes with a narrow frequency search space based on the average measured Doppler shift of the actual satellites detected in smaller modes with a wider frequency search space weighted by the measured C / N, provided that more than X satellites are detected and the wireless device is stationary. Valid satellites include measured peaks that have passed false alarm, noise, interference, cross-correlation, or other tests.

The tracking mode is used in normal operation to track any deviations of the average GPS Doppler shift independent of the CDMA channel, and in this mode a longer tracking time constant for the IIR is applied.

The counter in the EH memory of the wireless device monitors how many times the capture mode is executed. The capture mode switches to the tracking mode after the counter reaches the set value, which in one embodiment is equal to approximately four IIR capture time constants. According to the present invention, the correction scheme for the Doppler shift independent of the CDMA channel is different in the factory verification mode, which is limited only by the open loop mechanism, since in the factory mode switching of update, capture, and tracking element elements is not performed. In addition, the variable volatile memory, which is initialized with the element EH value, can be used for a closed loop situation in which this variable volatile memory will be updated with the IIR state based on the average Doppler shift for all reported real measurements, and then used to re-center the search windows for smaller modes with wider frequency search space. For the most sensitive modes with a narrow frequency search space, the re-centering of the Doppler window can be based on the average measured Doppler shift of the actual satellites that were detected in smaller modes with a wider frequency-search space, similar to re-centering the Doppler search windows used in the capture mode. It should be noted that the time constant of the factory IIR test mode may differ from the normal mode, and X may be set to zero.

In one embodiment, only one initial measurement time is used, even if the measurement can be carried out at different times. This requirement is imposed by the IS-801.1 standard. For each measurement, there is TIME_MEASER provided by the digital signal processor (DSP), which represents the time the measurements were taken. GPS and AFLT code phase measurements should be extended to the total time before reporting them in the pseudo-distance and control phase measurements in IS-801.1 messages, respectively, or before being used in the location mechanism, even if one or more visits are required to complete this search . In this particular embodiment, the selected total time is a C / N-weighted average for all GPS measurement times that are quantized to the closest GPS visit start time.

The propagation errors of GPS and AFLT code phase measurements by the total time TIME_REF directly increase the errors in calculating the location of the wireless device. The Doppler shift used in time propagation is a measured Doppler shift, not predicted, and therefore any errors in the measured Doppler shift will directly affect the accuracy of the location. This result is especially pronounced in scenarios with large windows in which a maximum session time of thirty seconds can lead (for example, if the error of the CDMA channel independent of the Doppler shift of GPS of 10 Hz is not taken into account) to a location error of 57 meters (assuming DOP = 2).

The measured GPS code phase and the measured GPS Doppler shift for a particular satellite at the time TIME_MEZER are represented by GPS chips measure_code_phase and additional_measure in Hz, respectively. To evaluate this code phase at some other point in time, it is necessary to use the Doppler frequency measured by the wireless device, the doppler measured in Hz at the time TIME_MEASER, or the predicted first-order Doppler shift (DOPLER1, measured in Hz per second) provided in the Help to capture from UOM (in the case of determination using the MS) or predicted by the wireless device (in the case of determination in the MS itself and the autonomous case).

To extend the GPS code phase measurement to the total time, TIME_REF, in the absence of a Doppler shift of GPS, the following equation is used:

extension_phase_code (REF_TIME) = measure_phase_code (TIME_MEASURE) +

·Δt·допл_измер(Δt) (Уравнение 1)

Δt extra dimer (Δt) (Equation 1)

where Δt = TIME_REF - TIME_IME (seconds) and

add_measure (x) = add_measure +

- частота чипов GPS=1,023 МГц.while f _L1 is the GPS frequency L1 = 1.57542 GHz and

- GPS chip frequency = 1,023 MHz.

It can be noted that if the propagation time Δt is large and if there is also a large error component in the doppler measurement as a result of the Doppler shift of GPS measurements, as discussed above, then these factors are combined, which leads to a large error in the common GPS code phase. It should be noted that the propagation time Δt will be large when the GPS session exceeds the time allocated to one GPS visit, for example, approximately two seconds, so it should be divided into several GPS visits. Between GPS visits and for structural reasons, the wireless device should be back in CDMA mode. The minimum CDMA reverse tuning time, defined to reduce the frequency of call loss and affect the quality of the speech signal, is approximately two seconds. The largest possible propagation time is equal to the maximum allowed GPS session time, i.e. about thirty seconds.

To better explain the principle of the GPS code phase error increasing as a result of the Doppler shift of GPS measurements, it should be noted that the measured GPS Doppler shift will consist of a true GPS Doppler shift, which ideally is very similar to the predicted GPS Doppler shift, and an unwanted GPS Doppler shift. A true GPS Doppler shift will occur both during a GPS visit and when reverse tuned to CDMA, as it reflects the satellite’s movement during GPS and CDMA visits. As a result, the true GPS Doppler shift is used in the propagation equation throughout the Δt period. The GPS Doppler shift may consist of a Doppler shift independent of the CDMA channel and / or dependent on the CDMA channel; The GPS Doppler shift, dependent on the CDMA channel, will also occur during GPS and CDMA visits, as the UNUTG value will be shifted by the amount of the intentionally entered frequency error in the CDMA and GPS modes. On the other hand, a GPS Doppler shift independent of the CDMA channel occurs only during GPS visits, but not reverse CDMA tuning. This is due to the fact that during the reverse tuning on CDMA, a frequency control loop is turned on, which brings any residual Doppler shift independent of the CDMA channel to 0 Hz. As a result, a CDMA channel independent Doppler shift should not be used during the entire Δt propagation period, but only when propagated to GPS visits.

Given the possible presence of the GPS Doppler shift, doppler shift in the measured GPS Doppler shift at the time TIME_MEASURE, we can record:

add_measure = add_true + add_shift = add_true + EN_DOPLER_SHIFT + f _L1 ∗ DMSS_DOPLER_SHIFT,

where EN_DOPLER_SHIFT is the CDMA channel-independent part of the GPS Doppler shift in Hz at the time TIME_MEASER, and DMSS_DOPLER_SHIFT is the CDMA channel-dependent part of the Doppler shift at time TIME_IMER, normalized by the CDMA channel frequency, at which it is calculated and true, and moment TIME_IMER.

Next, we denote M consecutive reverse settings for CDMA between TIME_REF and TIME_MEASER as reverse CDMA settings 1,2, ... M, where reverse CDMA setting 1 is the reverse setting for CDMA, closest in time to TIME_REF, reverse CDMA setting 2 is the next reverse the CDMA setting closest in time to TIME_REF, and so on, and the reverse CDMA setting M is the reverse setting for CDMA closest in time to TIME_MERE. We denote the successive time boundaries of these reverse CDMA settings as t _{1,2, ... 2M} .

It follows from this that if the spread of code phase measurements occurs backward in time, i.e. from TIME_MEASER to some earlier TIME_REF (i.e. TIME_REF <TIME_MEASURE), as shown in FIG. 2a, the marking of M consecutive inverse CDMA settings between TIME_REF and TIME_MEASE coincides with their order in time, i.e. reverse CDMA tuning 1 will be the first, and reverse CDMA tuning M will be the last CDMA tuning in time. In this case, t _{1,2, ..., 2M} represents the start time and end time of these reverse settings on CDMA. If the GPS code phase measurements should propagate forward in time, i.e. from TIME_MEASER to some later time TIME_REF (i.e. TIME_REF> TIME_MEASURE), as shown in FIG. 2b, the marking of M consecutive reverse CDMA settings between TIME_REF and TIME_MEASER will be opposite to their order in time. Namely, reverse CDMA tuning 1 will now be the last, and reverse CDMA tuning M will be the first reverse tuning to CDMA in time, and t _{1,2, ..., 2M} now represents the time of their end and start.

Figures 1 and 2a illustrate the propagation of GPS code phase measurements backward in time to an earlier TIME_REF, as will be described in more detail below. FIG. 2b illustrates forward propagation at a later time TIME_REF and is included to explain the definitions used. For simplicity, the assumption is made in all figures that DOPLER1 is 0.

Using the above definitions, we can write the following:

Δt _CDMA = part of Δt spent on reverse settings on CDMA =

=

Δt _GPS - part of Δt spent on GPS visits = Δt-Δt _CDMA .

It should be noted that for a GPS session consisting of only one GPS visit, i.e. M = 0,

Δt _CDMA = 0, and

Δt _GPS = Δt = TIME_REP-TIME_MEASURE.

Note that, as it has been determined, all Δt, Δt _GPS and Δt _CDMA can have positive or negative values, depending on whether the measurements propagate forward (i.e. TIME_REF> TIME_MEASURE) or backward (i.e. TIME_REF <TIME_MEASURE) by time.

First, suppose that both the CDMA independent GPS Doppler shift and the CDMA dependent Doppler shift are constant during the entire GPS session when they are present, then the equation for propagating GPS code phase measurements will take the form

Since the PS measures the total GPS Doppler shift at the time TIME_MEAS rather than the doppler truth, all calculations in the PS will be in units of the total measured GPS Doppler shift, doppler. Expressing the above equation in units of the total measured GPS Doppler shift, we obtain:

It should be noted that both equations 1 and 2 work equally well in a situation with one GPS visit, since in this situation the measurement is not propagated in any reverse configuration on CDMA, i.e. Δt _CDMA = 0. However, in the case of multiple visits, equation 1 will give an error in the common code phase, which will be equal to

·ЭН_ДОПЛЕР_СДВИГ (Уравнение 3) Error [GPS chips] = - Δt _CDMA ·

· EN_DOPLER_SHIFT (Equation 3)

To further illustrate this point, FIGS. 1 and 2 show the propagation of the GPS code phase backward in time for a session consisting of one or more GPS visits, respectively. For simplicity, in this example, we assume that DOPLER1 is zero. To allow the maximum propagation time, TIME_REF is selected as the initial one, and TIME_IMER as the final one in the GPS visit for the case with one GPS visit, as shown in FIG. 1, and at the beginning of the first and end of the last GPS visit for the case with multiple visits, respectively, shown in figa.

Figure 1 illustrates that both equations 1 and 2 give the correct answer for phase_code in the case of a single GPS visit session. However, in the case of a plurality of GPS visit sessions, as shown in FIG. 2a, Equation 1 underestimates the distribution of the phase for the error value given in Equation 3. To determine the magnitude of this error, suppose that EN_DOPLER_SHIFT is 10 Hz, and DMSS_DOPLER_Shift is 0 Hz . For 7 reverse CDMA settings during this GPS session, Δt _CDMA = 14 seconds, as shown in FIG. 2a, which results in a code phase propagation error of 0.0909 GPS chips, or equivalent to 26.66 meters, assuming DOP = 1 , or 53.23 meters with the assumption of DOP = 2, if equation 1 is used, and not equation 2 for the propagation of the GPS code phase.

обозначает время, когда происходят переключения частоты CDMA 1,2,…,N. И, наконец, суммарный доплеровский сдвиг GPS и нормированная зависимая от канала CDMA часть доплеровского сдвига GPS между последовательными переключениями частоты CDMA i и (i+1) обозначены как допл_сдвиг_i и ДМСС_ДОПЛЕР_СДВИГ_i, соответственно, так что суммарный доплеровский сдвиг GPS и зависимая от канала CDMA часть доплеровского сдвига между ВРЕМЯ_РЕФ и

обозначены как допл_сдвиг₀ и ДМСС_ДОПЛЕР_СДВИГ₀, между

и

обозначены как допл_сдвиг₁ и ДМСС_ДОПЛЕР_СДВИГ₁ и т.д., и, наконец, между

и ВРЕМЯ_ИЗМЕР обозначены как допл_сдвиг_N и ДМСС_ДОПЛЕР_СДВИГ_N, соответственно.In addition, it should be noted that in equations 2 and 3, as well as in all the figures, the assumption was used that the Doppler shift remains constant throughout the duration of the GPS session, i.e. for multiple GPS visits for a GPS Doppler shift independent of the CDMA channel, and for many GPS visits and CDMA reverse settings for a GPS Doppler shift dependent on the CDMA channel. It should be noted that this may not be true for part of the GPS Doppler shift, dependent on the CDMA channel, since the wireless device may be in a frequency switching state during reverse tuning to CDMA in any session. Therefore, if we assume that there are N CDMA frequency switching during a GPS session, the CDMA channel dependent part of the GPS Doppler shift can change N times. Using the appropriate nomenclature, we can designate N consecutive switching of the CDMA frequency between TIME_REF and TIME_MEASER , if they occur, as switching frequency 1.2, ..., N, where switching 1 CDMA frequency is the switching CDMA frequency closest in time to TIME_REF, switching 2 of the CDMA frequency is the next closest in time to TIME_REF, and so on, and switching N of the CDMA frequency is the closest in time to TIME_MEASER. Wherein

indicates the time when the CDMA frequency switching 1,2, ..., N. And finally, the total GPS Doppler shift and the normalized CDMA channel-dependent portion of the GPS Doppler shift between successive CDMA frequency switching i and (i + 1) are designated as doppler shift _i and DMSS_DOPLER_SHIFT _i , respectively, so that the total GPS Doppler shift and channel dependent CDMA part of the Doppler shift between TIME_REF and

denoted as dop_shift ₀ and DMSS_DOPLER_SHIFT ₀ , between

and

are designated as dop_shift ₁ and DMSS_DOPLER_SHIFT ₁ , etc., and finally between

and TIME_IMER are designated as dop_shift _N and DMSS_DOPLER_SHIFT _N , respectively.

и допл_сдвиг₀ являются первыми, а переключение частоты CDMA N,

и допл_сдвиг_N - последними во времени. Альтернативно, при распространении их вперед во времени, маркировка N последовательных переключений частоты CDMA между ВРЕМЯ_РЕФ и ВРЕМЯ_ИЗМЕР, их время и соответствующие доплеровские сдвиги GPS будут обратными их порядку во времени.This marking chosen for use may not coincide with the actual sequence in time. When GPS and AFLT code phase measurements are propagated back in time, the marking of N consecutive CDMA frequency switching and the time of their occurrence, as well as the marking of the corresponding GPS Doppler shifts, coincide with their order in time, while CDMA frequency switching 1,

and dop_shift ₀ are the first, and CDMA N frequency switching,

and dop_shift _N - last in time. Alternatively, as they propagate forward in time, the marking of N consecutive switching of the CDMA frequency between TIME_REF and TIME_MEASER, their time and the corresponding GPS Doppler shifts will be inverse to their order in time.

Using the above definitions, we can write the following:

where ENDOPLER_SHIFT is the CDMA channel-independent part of the GPS Doppler shift in Hz, assumed constant in all GPS visits during the entire GPS session, and DMSS_SHIFT_Is _i is the CDMA channel-dependent part of the GPS Doppler shift between the i-th and (i + 1) -th switching the CDMA frequency, normalized to the CDMA frequency at which it is calculated. Using the above definition, equation 1a takes the form:

Так как ПС измеряет суммарный доплеровский сдвиг GPS в момент ВРЕМЯ_ИЗМЕР, а не допл_измер, все вычисления в ПС будут в единицах суммарного измеренного доплеровского сдвига GPS, допл_измер. Выразив приведенное выше уравнение 3а в единицах измеренного доплеровского сдвига GPS, получим уравнение 2 в присутствии переключений частоты CDMA во время сеанса GPS в следующей форме:

Since the PS measures the total GPS Doppler shift at the time TIME_MEAS rather than the dop_measure, all calculations in the PS will be in units of the total measured GPS Doppler shift, dop_measure. Expressing the above equation 3a in units of measured GPS Doppler shift, we obtain equation 2 in the presence of CDMA frequency switching during a GPS session in the following form:

Таким образом, в предложенном способе коррекции доплеровского сдвига GPS будет использоваться уравнение 4 для распространения измерений кодовой фазы GPS на общее время до их передачи в сообщении IS-801.1 ИПР в УОМ или до их использования в собственном механизме определения местоположения устройства.

Thus, in the proposed method for correcting the Doppler shift of GPS, Equation 4 will be used to extend the GPS code phase measurements to the total time until they are transmitted in the IP-message IS-801.1 IPR in the UOM or before they are used in the device’s own location mechanism.

And finally, in the event that the designers of the wireless device decide to use PLL systems that deliberately have static errors in the output frequency, AFLT measurements will also experience a Doppler code shift dependent on the CDMA channel. In order to guarantee the correct distribution of all AFLT measurements to the total time before they are reported to the PTO through the IP-message IS-801.1 or before their use in the location mechanism of the wireless device, this Doppler shift of the CDMA code must be taken into account accordingly according to the following equation:

distribution_phase_code_AFLT (TIME_REF) = measure_phase_code_AFLT (TIME_MAS_AFLT) +

- время, при котором возникли эти переключения частоты CDMA 1,2,…,N, как было определено выше.where AFLT is the measured code phase for a particular control signal at the time TIME_MEASURE_AFLT is given in CDMA chips measured_code_phase_AFLT, and the code phase AFLT, distributed over the total time TIME_REF, is given in CDMA chips the frequency distribution_code_AFLT, TIME TIME and the number of times between the number of times and the number of times between the time and the number of time are set to the right.

- the time at which these switching frequency CDMA 1,2, ..., N, as defined above.

The method described above can be implemented, for example, by controlling a wireless device so that it executes a sequence of computer-readable instructions. These commands can reside in various types of signal-carrying environments. In this regard, one aspect of the present invention relates to an industrial product comprising a signal carrying medium materially implementing a program of computer-readable instructions executed by a digital signal processor to perform a method for determining the location of a transceiver used in a synchronous communication network using wireless communication lines.

This signal carrier medium may be, for example, RAM (not shown) contained in a communication network. Alternatively, instructions may be included in other carrier signals of the medium, such as a floppy disk for magnetic data storage or other digital medium, directly or indirectly accessible to a wireless device or system. Regardless of whether they are contained in a communications network or elsewhere, commands can be stored on various computer-readable storage media, such as direct-access storage devices, magnetic tape, electronic read-only memory, optical storage, or any suitable medium, carrier signals. In one illustrative embodiment of the invention, machine-readable instructions may comprise strings of a compiled C or C ++ programming language or another suitable language commonly used by programmers.

A method and apparatus for performing location determination in a wireless communication system have been described. The foregoing description of the preferred embodiments will enable any person skilled in the art to make or use the present invention. Various modifications of these options will be apparent to those skilled in the art, and the general principles of the invention can be applied to other options without resorting to creative efforts. Thus, the present invention is not limited to the described options, but has a scope consistent with the described principles and new essential features.

Claims (10)

1. A method for propagating measurements of a control phase of a forward link triangulation method (AFLT) for a total time to determine the location of a wireless device, comprising: determining a Doppler shift of a code division multiple access (CDMA) code dependent on a CDMA channel, and accounting for the Doppler shift CDMA code during the distribution of the time AFLT measurements of the control phase to the total time until the AFLT reports the measurements of the control phase to the location unit (PTO) or before using AFLT measurements the control phase in the positioning mechanism in the wireless device. 2. The method according to claim 1, in which the distribution of AFLT measurements of the control phase is determined by continuously calculating the Doppler shift of the CDMA code. 3. A method for optimizing the location of a wireless communication device based on the Global Positioning System (GPS) in the presence of a time-varying frequency error, comprising: determining a GPS Doppler shift value, including determining a CDMA Doppler shift value, centering the GPS Doppler search window to based on the magnitude of the Doppler shift of GPS, the correction of the magnitude of the Doppler shift of GPS during the propagation time of GPS measurements of the code phase to the total time ktsiyu largest CDMA code doppler shift during propagation time AFLT code phase measurements to common time. 4. The method according to claim 3, in which the GPS Doppler shift value is subtracted from the measured GPS Doppler value until the measured GPS Doppler value is reported to the location unit (PTO) or before the measured GPS Doppler value is used in the location and / or speed mechanism in wireless device. 5. A method for optimizing the location of a GPS-based wireless communication device in the presence of a time-varying frequency error, comprising: determining a GPS Doppler shift value, centering a GPS Doppler search window based on a GPS Doppler shift value, correcting a GPS Doppler shift value during time propagation GPS measurements of the code phase for the total time, saving the value of the Doppler shift independent of the CDMA channel in the memory of the cellular device, saving the calculated values the order of the Doppler shift of the GPS dependent on the CDMA channel and the Doppler shift of the CDMA code, wherein the stored value of the Doppler shift of the CDMA code dependent on the CDMA channel is used to spread the AFLT measurements of the code phase over the total time, and the use of a GPS Doppler value independent of the CDMA channel, and the GPS Doppler shift value dependent on the CDMA channel for re-centering the GPS Doppler shift window for all search modes. 6. The method of claim 5, wherein the GPS Doppler shift independent of the CDMA channel and the GPS Doppler shift dependent on the CDMA channel are used to propagate GPS code phase measurements to the total time. 7. A wireless communication device for optimizing the location of a GPS-based wireless communication device in the presence of a time-varying frequency error, comprising: a receiver for receiving signals from a base station, the signals including an indication of GPS satellite synchronization, a GPS receiver and a control processor, connected to the receiver and the GPS receiver and configured to use the received GPS satellite time to determine the center of the Doppler GPS search window to search for this satellite, and The center of the GPS Doppler search window is determined by determining the total GPS Doppler shift value and centering the GPS Doppler search window based on the total GPS Doppler shift value, while the CDMA code Doppler shift value dependent on the CDMA channel is calculated and taken into account when spreading the AFLT time of code phase measurements for the total time until the AFLT code phase measurements are reported to the positioning unit (PTO) or AFLT code phase measurements are used in the location determination mechanism without a wired device. 8. The material storage medium when determining the location of a wireless communication device, containing executable data that can induce a programmable device to perform the steps of: determining the center of the Doppler GPS search window to search for a satellite of the global positioning system (GPS), including: determining the magnitude of the GPS Doppler shift including determining the magnitude of the Doppler shift of the CDMA code; and centering the GPS Doppler search window based on the GPS Doppler shift value; and accounting for the Doppler shift of the GPS and the Doppler shift of the CDMA code when propagating GPS measurements of pseudo-distance and AFLT measurements of the control phase, respectively, for the total time. 9. The material storage medium of claim 8, wherein the GPS Doppler search window is determined by continuously measuring and / or calculating the GPS Doppler shift value. 10. The material storage medium according to claim 8, which also takes into account the continuously measured and / or calculated Doppler shift of the GPS and the continuously calculated Doppler shift of the CDMA code when propagating GPS measurements of pseudo-distance and AFLT measurements of the control phase, respectively, for the total time.

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