CN103091683B - Assist type is based on the location of satellite-signal - Google Patents

Abstract

Disclose the location of a kind of assist type based on satellite-signal.In order to auxiliary satellite-based location, receive the parameter being used at least one satellite.At random redundant information is removed from these parameters.Then provide the parameter of the redundance with reduction as the auxiliary data for the location based on satellite-signal.On the other hand, this type of parameter with the redundance of reduction can be received as the auxiliary data for the location based on satellite-signal.Then, initial parameter is rebuild by adding removed redundant information to received parameter.Rebuild initial parameter is used in the location of assist type based on satellite-signal.

Description

Assisted satellite signal-based positioning

This application is a divisional application with application number 200680056432.8, application date September 21, 2006, and titled "Auxiliary Positioning Based on Satellite Signals".

technical field

The present invention relates to assisted satellite signal based positioning.

Background technique

Various Global Navigation Satellite Systems (GNSS) support positioning of devices. These systems include, for example, the US Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS), the future European system Galileo, the Space Based Augmentation System (SBAS), the Japanese GPS Augmented Quasi-Zenith Satellite System (QZSS) ), local area augmentation systems (LAAS), and hybrid systems.

GNSS typically includes multiple satellites orbiting the Earth. These satellites are also known as space vehicles (SV, spacevehicle). Each satellite transmits at least one carrier signal, which may be the same for all satellites. Each carrier signal is then modulated by a different pseudorandom noise (PRN) code that spreads the signal in the frequency spectrum. As a result, different channels are obtained for transmission via different satellites. The code includes a number of bits, which are repeated in cycles. The bits of a PRN code are called chips, and the cycle time is called an epoch of the code. The carrier frequency of the signal is further modulated with the navigation information at a bit rate significantly lower than the chip rate of the PRN code.

Navigation information may include satellite identifiers (SVIDs), orbit parameters, time parameters, and other information. The satellite identifier indicates the satellite to which the data in the navigation information is applied. It can be an ordinal number, for example. Orbit parameters may include ephemeris parameters and almanac parameters. The ephemeris parameters describe a shorter segment of the orbit of the corresponding satellite. They may for example include parameters indicating the semi-major axis and eccentricity of the ellipse along which the satellite is currently traveling. Based on the ephemeris parameters, the algorithm can estimate the position of the satellite at any time when the satellite is in the described sector of the orbit. The almanac parameter is also similar, but it is a rough orbit parameter, and the valid time of the almanac parameter is longer than that of the ephemeris parameter. It is to be noted that in the case of almanacs, all satellites transmit almanac parameters for all satellites in the system, including the SVID indicating to which satellite the corresponding almanac parameter belongs. The time parameter defines a clock model that relates satellite time to the GNSS system time and system time to Coordinated Universal Time (UTC). In addition, they include a time-of-ephemeris (TOE) parameter indicating the reference time of the ephemeris, and a time-of-clock model (TOC) parameter indicating the reference time of the clock model.

In the case of GLONASS, the terms "direct information" and "indirect information" are used instead of the terms "ephemera" and "almanac". It should be understood that any references to "ephemera" and "almanac" in this document are used to denote all possible terms that can be used for the same kind of information, including GLONASS "direct information" and "indirect information".

The GNSS receiver whose position is to be determined receives the signals transmitted by the currently available satellites and it acquires and tracks the channels used by the different satellites based on the different PRN codes included. The receiver then determines the time of transmission of the code transmitted by each satellite, typically based on data in the decoded navigation message and based on a count of chips and the time of occurrence of the PRN code. The time of transmission and the measured arrival time of the signal at the receiver allow the determination of the pseudorange between the satellite and the receiver. The term pseudorange refers to the geometric distance between the satellite and the receiver, which is biased by receiver offset from GNSS time and unknown satellites.

In one possible solution, the offset between the satellite and the system clock is assumed to be known, and the problem reduces to solving four unknowns (i.e., the three receiver position coordinates and the receiver and GNSS system The nonlinear system of equations for the offset between clocks). Therefore, at least four measurements are required to solve this system of equations. The result of the process is the receiver position.

In some environments, a GNSS receiver is able to acquire and track enough satellite signals to make a position fix based on the PRN code, but the quality of the signals may not be high enough to decode the navigation message. For example, this may be the case in an indoor environment. Furthermore, decoding navigation messages requires considerable processing power, which may be limited in mobile GNSS receivers.

If a GNSS receiver is included in or attached as an accessory to the cellular terminal, the cellular network can provide the cellular terminal with assistance data comprising parameters extracted from decoded navigation messages via the cellular link. Such supported GNSS-based positioning is known as Assisted-GNSS (AGNSS). The received information enables the GNSS receiver or associated cellular terminal to obtain a position fix in less time and under more challenging signal conditions. Assistance data is typically provided for each satellite visible to the GNSS receiver associated with the cellular terminal. The assistance data may include navigation model parameters, which typically include orbit parameters, TOE and TOC parameters, and SVID parameters.

In addition, external services can provide long-term orbits, which are accurate and much longer than orbit models (ephemera/almanac) in SV broadcasts.

Contents of the invention

To provide assistance data, the parameters in the navigation information may be copied to the assistance message in their original format. The bandwidth required to transmit such assistance messages is considerable, but in some wireless communications, such as cellular communications, bandwidth is a critical factor.

From a first aspect considered, there is provided a method comprising receiving parameters for at least one satellite. The method also includes arbitrarily removing redundant information from the parameters, and providing the parameters with reduced redundancy as assistance data for satellite signal based positioning.

From a first aspect considered there is also provided an apparatus comprising a processing component. The processing component is configured to receive parameters related to at least one satellite. The processing component is further configured to optionally remove redundant information from the parameters. The processing component is further configured to provide the parameters with reduced redundancy as assistance data for satellite signal based positioning.

The processing components of the device provided for the first aspect considered may be implemented in hardware and/or software. It may, for example, be a processor executing software program codes for realizing the required functions. Alternatively, it may be, for example, a circuit designed to realize the required function, for example implemented in a chipset or chip such as an integrated circuit.

The device provided for the first aspect considered may eg comprise the same processing components, but it may also comprise additional components. The device may also be, for example, a module provided for integration into a stand-alone device or an accessory device.

For the first considered aspect, there is also provided an electronic device comprising the device provided for the first considered aspect. Additionally, it may include a wireless communication component and/or a satellite signal receiver configured to transmit information via a wireless link. The electronic device may eg be a network element of a wireless communication network, such as a base station of a cellular communication network, a local measurement unit connected to such a network element or a server connected to such a wireless communication network.

Considering a first aspect, there is also provided a computer program product, wherein computer program code is stored on a computer readable medium. When executed by a processor, said computer program code will implement the method provided for the first considered aspect. The computer program product may eg be a separate storage device or a component to be integrated into a larger device.

It shall be understood that the present invention also covers such computer program code independently of the computer program product and computer readable medium.

From a second aspect considered, there is provided a method comprising receiving parameters as assistance data for satellite signal based positioning, wherein the received parameters are based on original parameters of at least one satellite, from which original parameters Redundant information is arbitrarily removed. The method also includes reconstructing the original parameters by adding the removed redundant information to the received parameters. The method also includes using the reconstructed raw parameters in assisted satellite signal-based positioning.

From a second aspect of consideration there is also provided an apparatus comprising a processing component. The processing component is configured to receive parameters as assistance data for satellite signal based positioning, wherein the received parameters are based on original parameters of at least one satellite from which redundant information has been arbitrarily removed. The processing component is further configured to reconstruct the original parameters by adding the removed redundant information to the received parameters. The processing component is also configured to use the reconstructed raw parameters in assisted satellite signal-based positioning.

Likewise, the processing components of the device provided for the second considered aspect may be implemented in hardware and/or software. It may, for example, be a processor executing software program codes for realizing the required functions. Alternatively, it may be, for example, a circuit designed to realize the required function, for example implemented in a chipset or chip such as an integrated circuit.

Furthermore, the device provided for the second considered aspect may also eg comprise the same processing components, but it may also comprise additional components. The device may also eg be a module provided for integration into a stand-alone device or an accessory device.

For the second considered aspect, there is also provided an electronic device comprising the device provided for the second considered aspect. Additionally, it may include a wireless communication component and/or a satellite signal receiver configured to receive information via a wireless link. Said electronic device may eg be a terminal of a wireless communication system, such as a cellular terminal or an accessory of such a terminal.

From a second aspect of consideration there is also provided a computer program product, wherein computer program code is stored on a computer readable medium. When executed by a processor, said computer program code will implement the method provided for the second considered aspect. The computer program product may eg be a separate storage device or a component to be integrated into a larger device.

It shall be understood that the present invention also covers such computer program code independently of the computer program product and computer readable medium.

Finally, there is provided a system comprising the apparatus provided for the first considered aspect and the apparatus provided for the second considered aspect.

On the other hand, the invention is based on the consideration that especially (though not exclusively) the raw format of the parameters transmitted in the satellite signal necessarily has some redundancy, which is required by the type of transmission path. In satellite broadcasting, there may be periodic outages etc. and it is not always possible to collect all the data bits at the satellite receiver. Redundancy may be due, for example, to a large amount of overhead data provided for error correction or the like. On the other hand, the link used to provide the assistance data can be more reliable and bit error-proof, so that the above-mentioned overhead is not needed. Furthermore, corresponding parameters for different satellites transmitted in parallel may be very similar to each other. If the parameters of several satellites are provided as assistance data to a single device in this way, a set of corresponding parameters also includes redundancy. Therefore, it is proposed to remove redundancy from the parameters in their original format. It will be appreciated that redundancy will be arbitrarily removed from the parameters; some parameters in the assistance data may thus remain unchanged.

Thus, the invention results in a reduced bit consumption for assistance data for assisted satellite-based positioning. For example, in cellular transmissions, the bandwidth savings achieved are valuable. The bit count required for a particular parameter can be reduced without losing precision or compatibility with the original format (which is used by the corresponding satellite system).

The raw parameters may be extracted from one or more satellite signals. As in the case of almanacs, a single satellite can also transmit the parameters of several satellites, as mentioned above. Alternatively or additionally, parameters may be received from other sources such as servers providing long-term orbits. In this case, the parameters can be provided eg using Internet Protocol (IP) based methods (user plane) or in the control plane.

There are different options for removing redundancy from a parameter, depending on the kind of parameter in question. Said reduction can be achieved by considering the parameters themselves, but especially by considering a set of corresponding parameters in combination.

In one embodiment, arbitrarily removing redundant information from said parameters comprises determining a common part and corresponding individual parts of a plurality of parameters. Then, the common part is provided as auxiliary data only once for the plurality of parameters.

If said parameters comprise parameters of satellites belonging to two or more different satellite systems, even a common part of the parameters of satellites belonging to different satellite systems can be determined. In addition, a corresponding common part of the parameters of the satellites belonging to a single satellite system can then be determined.

At a device receiving such assistance data, it may be possible by adding one or more common parts received in said assistance data for a plurality of original parameters to the corresponding Individual parts to reconstruct the original parameters.

This method is suitable for different kinds of parameters. For example, it can be used for multiple eccentricity parameters and/or multiple semi-major axis parameters and/or multiple time parameters indicating respective points in time. These parameters may originate from ephemeris parameters, almanac parameters or even some external source such as a commercial long-term orbit service. In assistance data, orbital parameters are typically sent for each satellite visible to the aid. Therefore, any reduction in the bit count of the navigation model will directly contribute to the bandwidth requirement.

The invention is also suitable for harmonizing representations across the systems considered, if a common part is available for parameters or sets of parameters of different satellite systems.

If the parameters include, for example, corresponding eccentricity parameters of a plurality of satellites, arbitrarily removing redundant information from the parameters may comprise separating the plurality of eccentricity parameters into a common most significant bit (MSB, mostsignificantbit) part and The corresponding individual least significant bit (LSB, leastsignificantbit) part. The common MSB part may be provided as auxiliary data only once for the plurality of eccentricity parameters. In contrast, individual LSB portions may be transmitted separately for each eccentricity parameter.

If the parameters include respective semi-major axis parameters of a plurality of satellites, arbitrarily removing redundant information from the parameters may comprise separating the plurality of semi-major axis parameters into a common MSB part and respective individual LSB parts. Then, the common MSB part may be provided as auxiliary data only once for the plurality of semi-major axis parameters. In contrast, individual LSB portions may be transmitted separately for each semi-major axis parameter.

As noted above, the embodiments provided for reducing redundancy in eccentricity and semimajor axis parameters can be used for ephemeris, almanac, and any other source that provides similar parameters.

If the parameters include a plurality of time parameters indicating respective points in time, arbitrarily removing redundant information from the parameters may comprise determining a common part and an individual part for the plurality of time parameters, the common part being indicative of a block of time A fixed time in , the individual part defines the deviation of the time point indicated by the corresponding time parameter from the fixed time. Then, said common part may be provided as auxiliary data only once for said plurality of time parameters. In contrast, individual parts may be transmitted separately for each time parameter.

Such temporal parameters for which a common portion is defined may include TOE parameters for multiple satellites or TOC parameters for multiple satellites. Where separate TOE and TOC parameters are available for satellites, both TOE and TOC parameters may also define similar points in time. Thus, the method can also be used for TOE parameters and TOC parameters of corresponding individual satellites. Most efficiently, a common part is determined for all TOE parameters and all TOC parameters of all considered satellites of one satellite system, or even for all TOE parameters and all TOC parameters of all considered satellites of several satellite systems.

If the parameters include corresponding satellite identification parameters for a plurality of satellites, the satellite identification parameters may be a bit representation of an ordinal number. In this case, redundant information may be arbitrarily removed from the parameter by converting the plurality of bit representations of the ordinal into a single bit mask representation of the ordinal. The efficiency of this method increases with the number of satellites considered. In fact, there may be a prior decision-making step which ensures that the method is only used if a predetermined number of satellites considered is exceeded, to avoid a possible data increase in the case of few satellites considered.

At a device receiving such assistance data, the original satellite identification parameters may be reconstructed by converting a single bit mask representation of an ordinal number into a multi-bit representation of an ordinal number corresponding to the original satellite identification parameter.

In some satellite systems, the satellite identification parameters include offsets. That is, more bits are used to represent the satellite identity than are required to distinguish all possible satellites.

In this case, arbitrarily removing redundant information from said parameters may comprise reducing the bit count of said parameters by removing a predetermined offset in the corresponding satellite identification parameter. This method can be used as an alternative to, or in addition to, the conversion to bitmask described above.

At the device receiving such assistance data, the original parameters may be reconstructed by converting the received satellite identification parameters with fewer bits into original satellite identification parameters with more bits by adding a predetermined offset. If a bitmask is also used in addition, the bitmask is first converted into bit representations, and then the offset is added to these bit representations in order to retrieve the original parameters.

Likewise, the provided embodiments for reducing redundancy in satellite identification parameters can be used for ephemeris, almanac, and any other source that provides similar parameters.

The almanac parameters include parameters defining the segments of the orbit as well as the reference time.

If the parameters include almanac parameters for a plurality of satellites, the almanac parameters may include almanac reference time information for each of the satellites. Also in this case, redundant information can be arbitrarily removed from said parameters by defining a common part comprising at least a part of said reference time information. The common part may then be provided as assistance data only once for the plurality of satellites. Depending on the satellite system considered, the common part may eg comprise a week count, some other coarse indication of time, or a full reference time indication. Any reference time indication may be used in its original format or in a modified format more suitable for separation.

If said parameters comprise almanac parameters of a plurality of satellites belonging to at least two satellite systems, redundant information can be arbitrarily removed from said parameters, for example by determining a common part for said almanac parameters, wherein said common part is denoted by Week counts for multiple satellites belonging to different satellite systems. Furthermore, a common part may be provided for the time-of-week of a plurality of satellites belonging to the same satellite system, and an individual part for the almanac of each of said plurality of satellites belonging to this satellite system data. This first option can be selected for one or more of the satellite systems under consideration. Alternatively or additionally, a common part may be provided for day counts of a plurality of satellites belonging to the same satellite system, and an individual part may be provided for the time of day of each of said plurality of satellites belonging to the same satellite system (timeofday) and almanac data. Alternatively or additionally, individual portions may be provided for day count, time of day and almanac data for each of a plurality of satellites belonging to the same satellite system. The latter option can also be selected for one or more of the satellite systems under consideration. Each common part is then provided as auxiliary data only once for the almanac parameter.

Said assistance data may be transmitted to a cellular terminal associated with the satellite signal receiver, for example via a cellular link. Alternatively, any type of data link may be used to transfer the assistance data to any device requiring the assistance data.

The present invention can be used with any kind of current and future AGNSS including but not limited to assisted GPSL5, Galileo, GLONASS, QZSS, LAAS, SBAS or combinations thereof. Possible SBAS include, for example, the Wide Area Augmentation System (WAAS) or the European Geostationary Navigation Overlay Service (EGNOS).

It should be understood that all of the exemplary embodiments provided can also be used in any suitable combination.

Other objects and characteristics of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are intended for illustrative purposes only and not as a limitation of the invention, the scope of which should be referred to the appended claims. It should also be understood that the drawings are not drawn to scale and that they are intended only to conceptually illustrate the structures and processes described herein.

Description of drawings

1 is a schematic diagram of a first system according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating exemplary redundancy reduction of orbital parameters in the system of FIG. 1;

FIG. 3 is a flowchart illustrating exemplary redundancy reduction of time parameters in the system of FIG. 1;

FIG. 4 is a flowchart illustrating exemplary redundancy reduction of SVID parameters in the system of FIG. 1;

Figure 5 is an arrangement of tables illustrating exemplary redundancy reduction of almanac parameters in the system of Figure 1;

FIG. 6 is a flowchart illustrating exemplary redundancy restoration of navigation model parameters in the system of FIG. 1; and

Figure 7 is a schematic diagram of a second system according to one embodiment of the present invention.

detailed description

Figure 1 provides an exemplary system according to the present invention that allows the transmission of assistance data for AGNSS based positioning via a cellular link using reduced bandwidth.

The system comprises a cellular terminal 110 , a base station 130 of a cellular communication network and a local measurement unit (LMU) 140 .

Cellular terminal 110 may be a cellular telephone or any other type of cellular terminal, such as a laptop computer. It comprises a processor 114 , a cellular communication component 112 linked to this processor 114 , a GNSS receiver 113 and a memory 115 .

The processor 114 is configured to execute computer program codes. Memory 115 stores computer program code, which can be retrieved by processor 114 for execution. The stored computer program code includes positioning assistance software (SW) 116 .

The base station 130 includes a processor 134 and a cellular communication component 132 linked to this processor 134 , a memory 135 and an interface (I/F) component 131 .

The processor 134 is configured to execute computer program codes. Memory 135 stores computer program code, which can be retrieved by processor 134 for execution. The stored computer program code includes positioning assistance software (SW) 136 .

The LMU 140 includes an interface component 141 and a GNSS receiver 143 linked to this interface component 141 .

LMU 140 may be linked to base station 130 via a connection established between interface components 131 and 141 . It has to be noted that any kind of matching interface components 131, 141 enabling a wired or wireless link may be used.

The cellular communication component 112 of the cellular terminal 110 and the cellular communication component 132 of the base station 130 are capable of communicating with each other using a cellular link.

Both GNSS receivers 113, 143 are configured to receive, acquire and track signals transmitted by satellites S1, S2 belonging to one or more GNSSs. At least GNSS receiver 143 is also configured to decode navigation messages included in such signals.

Assisted GNSS based positioning in the system of FIG. 1 will now be described with reference to FIGS. 2 to 5 .

Fig. 2 is a flowchart illustrating reduction of redundant information in orbital parameters.

The GNSS receiver 143 receives, acquires, tracks and decodes the signals transmitted by the k satellites S1 , S2 belonging to the respective GNSS (step 200 ). Supported GNSS signals include (by way of example) GPSL5, Galileo, GLONASS, SBAS and QZSS signals. The GNSS receiver 143 provides the obtained navigation messages of the k signals to the base station 130 via the interface components 141 , 131 .

Processor 134 executes positioning assistance software 136 . It extracts various navigation model parameters from the k navigation messages, including orbit parameters, time parameters and satellite identification (SVID) parameters (step 201). It must be noted that processor 134 may also receive additional GNSS-related parameters from some server (not shown), including orbital parameters for long-term orbits, in a manner similar to the processing of parameters extracted from satellite signals described below. the same way.

For example, the orbit for GalileoSV is specified in ESA document ESA-EUING-TN/10206: "Specification of Galileo and Giove Space Segment Properties Relevant for Satellite Laser Ranging" (July 2006).

The orbit is specified to have a semi-major axis of 29,601,000 meters and an eccentricity of 0.002. It is known from GPS that the semi-major axes of satellite orbits are very stable and do not vary much between satellites. More specifically, GPS satellite orbits vary by ±65 km around the nominal semi-major axis, which is expected to be the same as for Galileo.

The original Galileo format defines the eccentricity and semi-major axis parameters as follows:

A 32-bit parameter is used to describe the eccentricity for each satellite. The scale factor used is ^2-33 . The range is [0,0.49999].

Also, the square root of the semi-major axis of the orbit of each satellite is expressed by a parameter of 32 bits (unsigned) for each satellite. The scale factor used is ^2-19 m ¹ / ₂ . Since the semi-major axis is 29,601,000 meters, the resolution is on the order of 0.02 meters.

Since the eccentricity actually varies between 0 and 0.002, there is no need to cover the range [0,0.49999] for each satellite. In the example provided, each eccentricity parameter is thus divided into an MSB portion common to each satellite and an LSB portion specific to each satellite (step 210).

The MSB part consists of 7 bits and the scale factor is 2 ⁻⁸ . The range is then [0,0.49609375]. Each LSB portion consists of 25 bits and the scale factor is ^2-33 . The range is then [0,0.0039]. Combining such MSB parts with a corresponding one of the LSB parts will yield the original range and resolution. In fact, if you assume the eccentricity is in the range [0,0.002], you don't need the MSBs at all, since they always contain only 0. However, it may be desirable to preserve the MSBs since they occur in the native format, and therefore they may have some use in the future.

The processor 134 thus provides as assistance data a single MSB part (7 bits) common to all eccentricity parameters of the k satellites considered, and an individual LSB part (25 bits) for each eccentricity parameter (step 211 ).

According to the GPSL5 specification, for example, the semi-major axis also varies by about 65 kilometers around the nominal value of 29,601,000 meters. Therefore, the square root of the semimajor axis is in the range [5434.7,5446.7]. Since the variation of the semi-major axis is only ±65000 meters, it is not necessary to provide the full range of each satellite. It is further assumed that the Galileo orbit behaves similarly to the GPS orbit.

In the example provided, each semi-major axis parameter is thus also divided into an MSB part common to each satellite and an LSB part specific to each satellite (step 220).

When assuming that the semi-major axis varies by about △a=65 km around the nominal value a ₀ =29,601,000 meters, the bit representation of the upper and lower limits of the range is given by:

Thus, for any possible value in the covered range, there are 6 common MSBs and MSB=101010 ₂ =42 ₁₀ *2 ⁷ =5376 ₁₀ .

Thus, the MSB portion is chosen to include 6 bits and a scale factor of ²⁷ meters. The range is [0,8064.00000]m ¹ / ₂ . The LSB part is chosen to consist of 26 bits with a scale factor of ^2-19 meters. The range is [0,127.99999]m ¹ / ₂ .

The processor 134 thus provides as auxiliary data a single MSB part (6 bits) common to all semi-major axis parameters of the k satellites considered, and an individual LSB part (26 bits) for each semi-major axis parameter (step 221 ).

Thus, the overall savings in bit counts for orbital parameters obtained using the above method is (k*32+k*32) bits - (7+k*25+6+k*26) bits = (k-1)*13 bits .

Orbital parameters for signals originating from GNSS satellites other than Galileo satellites can be processed in a corresponding manner. It will be appreciated that, depending on the system, parameters other than eccentricity and semi-major axis may also be reduced to consume fewer bits.

Fig. 3 is a flowchart illustrating the reduction of redundant information in temporal parameters extracted from k decoded navigation messages.

For each system, the time parameters include Time of Ephemeris (TOE) and Time of Clock Model (TOC) parameters.

Currently, GNSS assigns bits to these parameters as summarized in the table below:

system Bits in TOE/TOC# Scale of TOE/TOC GPS L5 11/11 300 seconds/300 seconds Galileo 14/14 60 seconds/60 seconds QZSS 11/11 300 seconds/300 seconds GLONASS 7+2 30 minutes/45 minutes/60 minutes SBAS 13 16 seconds

For GPSL5 signals, timekeeping is based on time of week (TOW). Eleven bits using a scale factor of 300 seconds are provided for each of the TOE parameter and the TOC parameter.

For the Galileo signal, the timing is also based on weekly time intervals. In this case, 14 bits using a scale factor of 60 seconds are provided for each of the TOE parameter and the TOC parameter.

According to the L1C draft IS-GPS-800 (April 2006), the QZSS signal will be similar to the GPS signal L1C, while L1C and L5 will also be similar in terms of the navigation model with respect to the orbit model and the SV clock model. Therefore, L1C, L5, and QZSS can all be described ultimately by the same mode in the multimodal navigation model.

If these original formats were simply copied into ancillary messages for transmission, bits would be wasted due to the redundant data included.

For example, a single Galileo satellite might provide a TOE value of 400,000 seconds and a TOC value of 401,800 seconds. In raw format, 28 bits are required to represent this data. However, an alternative is to express the TOE and TOC values as "400,000+000,000" and "400,000+001,800", respectively. Thus, the TOE and TOC values have a common part of "400,000" and incremental parts of "000,000" and "001,800", respectively. This consideration can be used to save bits when choosing the common and delta parts appropriately. The delta portion of the expression is used to represent the deviation of the parameter value from the determined common value.

The same considerations apply similarly to Galileo and QZSS.

Therefore, when time parameters from k satellite signals are received, it is first determined whether they are parameters from GPS, QZSS or Galileo signals (step 230).

If yes, the common part is determined (step 231). Build the Commons section by breaking the week into 6-hour chunks. The choice of block length is limited by the applicable time of the model. The block length must be equal to or longer than the longest applicable time. In raw format, the maximum time is 4 hours. However, since long-term orbits must be taken into account, the block length is set to 6 hours. But it has to be pointed out that the choice of length is very arbitrary as long as it is longer than any suitable interval of the original GNSS format, so the choice of 6 hour blocks is just an example. Also, as the block length increases, the resulting reduction in bit count decreases because the number of bits required in the delta portion increases.

In the current example, the public part is described by using 5 bits of a scale factor of 6 hours, which results in a range of 0-186 hours. This allows representing entire weeks in 6-hour blocks. This common part is common to all TOE and TOC values in all k satellite signals.

The choice of individual increments for each satellite and each TOE and TOC value depends on the satellite system under consideration (step 232).

In case the satellite system under consideration is GPS or QZSS, for each of the k considered satellite signals, the individual incremental part of each TOC value is represented by 7 bits, and for the k considered Each of the satellite signals, the individual incremental portion of each TOE value is represented by another 7 bits (step 233).

The single common part and the k individual delta parts are then included in the auxiliary message. The total number of bits in the common part and the k individual incremental parts is thus (5+2*k*7) bits compared to the original (2*k*11) bits.

In the case where the satellite system considered is Galileo, for each of the k satellite signals considered, the individual incremental part of each TOC value is represented by 9 bits, and for the k satellite signals considered For each signal in , the individual incremental portion of each TOE value is represented by another 9 bits (step 234).

The single common part and the k individual delta parts are then included in the auxiliary message. The total number of bits in the common part and the k individual incremental parts is thus (5+2*k*9) bits compared to the original (2*k*14) bits.

In all three cases, the common part is the same for all TOC and TOE parameters of all SVs, while the delta part is temporal parameter and SV-specific. Therefore, minimizing the bit count in the delta portion will also minimize the overall bit usage.

In contrast, when time parameters from k satellite signals are received and they are determined to be parameters from GLONASS or SBAS signals (step 230), no common part is used for TOE and TOC values or for different satellites.

The reason is that in these cases the counting starts with diurnal variations, as opposed to other systems where timekeeping is based on weekly times. Since SBAS and GLONASS count their time on a daily basis, indicating the MSB of the 6-hour block for Galileo, GPS, QZSS, etc. is useless overhead from the perspective of SBAS and GLONASS. Therefore, the above MSB is not used for SBAS and GLONASS. Instead, use LSB only for SBAS and GLONASS.

In the original GLONASS format, TOE and TOC are represented by blocks starting from day. The number of blocks is represented by the value in the 7-bit field _tb . The extra value in the 2-bit field P1 indicates the length of the block, which can be 30, 45 or 60 cents. Place the TOE/TOC in the middle of the block. The parameters are used for both TOE and TOC, so only 7+2 bits are needed.

In the original SBAS format, the same 13-bit value is used for TOE and TOC in WAAS with a scale factor of ²⁴ seconds. Counting also starts with GPS diurnal variation.

Therefore, the number of LSBs in this case is case-by-case. That is, for SBAS they include 13 bits, but for GLONASS they only include 9 bits. Therefore, the number of LSBs will be a function of the GNSSID.

The bit count properties and scale factors of the SBAS are maintained in the provided embodiments. The reference time of the GLONASS parameter is also conveyed in the assistance message as it is broadcast by the SV, ie using 7+2 bits.

Furthermore, the individual parts of the TOE and TOC parameters for each satellite are divided into LSB and MSB parts. These LSB and MSB parts can be considered as sub-parts of LSB for Galileo, GPS, QZSS, etc.

For both GLONASS and SBAS systems, the 9 LSBs of each parameter are provided as the corresponding LSB portion of the assistance message (step 236).

In the case of GLONASS (step 237 ), only these 9 (7 bits for block count and 2 bits for flag P1 ) LSB bits are used in the auxiliary message.

In the case of SBAS (step 237), the remaining 4 bits of the 13 bits from the original SBAS format are provided as the corresponding MSB portion of the ancillary data (step 238).

It should be noted that the interpretation of the LSB section will vary depending on whether the system is SBAS or GLONASS.

The table below summarizes the bit savings of the different GNSS described with reference to Figure 3:

In the presented multi-mode navigation model, GPSL5 and QZSS are represented by the same mode because the navigation models may be identical in orbit and time in GPSL5 and QZSS.

In the multimodal navigation model provided, GLONASS and SBAS are represented by the same schema, since the orbital models in both are based on the Satellite position, velocity, and acceleration, then perturb the position based on the rate-of-change information.

FIG. 4 is a flowchart illustrating the reduction of redundant information in SVID parameters extracted from k decoded navigation messages.

The bit counts required to identify satellites in different GNSS are indicated in the table below:

In the case of GPSL5 signals, satellites are identified in raw format by a 5-bit SV index (which allows 32 different satellites to be identified). This will consume k*5 bits, where k is the number of satellites identified.

If assistance data is to be provided for more than 6 satellites (k > 6), k can be provided more bit efficiently by using a 32-bit bitmask where each bit indicates whether a particular satellite signal has been tracked SV index.

If the satellite system under consideration is GPS (step 240), the k*5 bit representation is converted into a 32-bit bitmask (step 241).

For example, if there are k=8 SV{1581018192230}, the PRN number will require 8*5=40 bits of bandwidth. In contrast, when the SV is represented by the bitmask [10001001010000000110010000000100], the same information is provided by using a bandwidth reduced by 8 bits.

In case the satellite system under consideration is Galileo (step 240), the same method applies. But in the case of Galileo, satellites are identified in raw format by a 6-bit SV index (which allows 64 different satellites to be identified). Thus, the 6-bit representation of the GalileoSVID for the k satellite signals is converted into a 64-bit bitmask (step 242). Bit savings can be achieved if assistance data is provided for more than 10 Galileo satellite signals (k > 10).

Again, at least for the almanac, it is stated in the Galileo SIS-ICD draft 0 "GalileoOpenServiceSignalInSpaceInterfaceControlDocument" dated 23 May 2006 provided by the Galileo Joint Executive that only 36 satellites send the almanac. Therefore, for the almanac, a 36-bit bitmask can be expected to be sufficient. This means that bits are already saved if assistance data is provided for more than 6 satellites (k>6).

In the original GLONASS format, 5 bits are used for the slot index identifying one of the 32 orbital slots, and an additional 5 bits are used for the frequency index identifying one of the 32 frequencies. If the satellite system under consideration is GLONASS (step 240), the k*5-bit representation of the time slot is converted into a 32-bit bitmask representation (step 243), as in the case of GPSL5. The k frequency indices are included in the assistance message without modification.

In the case of SBAS, 8 bits are used to represent the SVID in the original form, but only the values 120-138 are used for WAAS and EGNOS within the coverage range of 0-255. If the satellite system under consideration is SBAS (step 240), an 18-bit bitmask can be used to represent k*8 bits (step 244) when using an offset of 120, since the space to be described is only as large as 18 SVs long. Bit savings can be achieved if assistance data is provided for more than 2 satellites (k>2).

In the case of QZSS, it is also likely that only subspaces of available PRN numbers will be used. In this case, if the satellite system under consideration is QZSS (step 240), bit savings can be achieved similarly as in the case of SBAS.

Figure 5 is an arrangement of tables showing reduction of redundant information in almanac parameters extracted from decoded navigation messages.

Assume (by way of example) that the decoded navigation messages are from Galileo and GLONASS satellites.

The almanac parameters include a plurality of parameters, including a reference time with respect to the almanac. In the case of Galileo, the reference time includes the Galileo week and week time as specified in the above-mentioned GalileoSIS-ICD draft. In the case of GLONASS, the base time is described by two parameters, the count of days since January 1 of the previous leap year and the time of day (Toa), as described in GLONASSICD (Version 5.0, Moscow, 2002, Coordinated Scientific Information Center of the Ministry of Defense of Russia).

To achieve redundancy reduction, for GLONASS the day count since January 1 of the previous leap year is first replaced by the week count corresponding to the Galileo week count and the day count since the start of the week. The time of day (Toa) is maintained as described in GLONASSICD.

For Galileo almanac data and GLONASS almanac data, an 8-bit "week" count can now be used together. Do not use any scaling for week representations. This is shown in the first table of FIG. 5 .

In addition, Galileo is provided with its own public part, which includes 2-bit data issues (IODa, IssueodData) without scaling and 8-bit time of week (Toa) with 2 ¹² second scaling. IODa is a sequential number describing the version of the dataset. This is shown in the second table of FIG. 5 .

The actual almanac data are provided separately in the individual sections for each considered Galileo satellite. This is shown in the third table of FIG. 5 . The parameters involved are not specified. They are described in the aforementioned GalileoSIS-ICD draft. It is to be understood, however, that reduction schemes for the ephemeris parameters corresponding to those provided with reference to Figures 2-4 can likewise be used for the almanac parameters for any further reduction of redundancy.

For GLONASS, no own public section is provided or an empty public section. This is shown in the fourth table of FIG. 5 .

For each considered GLONASS satellite, the day count (day) and time of day (Toa) are provided separately in the individual section together with the actual almanac data. This is shown in the fifth table of FIG. 5 . Other included parameters were not specified. They are described in the GLONASSICD mentioned above. Again, it will be appreciated that reduction schemes for the ephemeris parameters corresponding to those provided with reference to Figures 2-4 may likewise be used for the almanac parameters.

For the sake of completeness, it's important to note that usually Toa refers to the term "annual calendar time". For Galileo, it was originally "week time" (plus week count), because Galileo timing is based on counting weeks and counting time in blocks of a week. For GLONASS, on the other hand, "Toa" is originally a count of days since the beginning of the most recent leap year and then counts the time within that day. So the interpretation of "almanac time" changes depending on GNSS.

It is to be understood that the same distribution can be used for the common and individual parts if only Galileo signals or only GLONASS signals are considered.

It is to be understood that alternatively the common part may be determined separately for each satellite system.

Furthermore, a similar division of the public and individual parts of the almanac parameters can be achieved for other GNSSs.

Furthermore, the provided division into common and individual parts should be understood as an exemplary embodiment only. For example, in an alternative embodiment, the "day" parameter in GLONASS could be a common part of the GLONASS satellites.

All parameters leading to the operation of Figures 2-5 thus have reduced redundancy. Together with other data extracted from the k navigation messages, they are inserted into the assistance message, which is transmitted by the base station 130 to the cellular terminal 110 via the cellular link. In the cellular terminal 110 the received assistance message is provided to a processor 114 .

Processor 114 executes positioning aid software 116 . It receives measurements from the GNSS receiver 113 about multiple acquired and tracked satellite signals, but possibly no decoded navigation data. The associated navigation data needed to locate the cellular terminal 110 is obtained from the assistance data, for example to speed up positioning or to enable positioning in those cases where it is not possible to decode navigation messages in acquired and tracked satellite signals.

Figure 6 is a flow diagram illustrating reconstruction of original navigation orbit parameters from parameters in received assistance messages.

Processor 114 extracts the low-redundancy eccentricity parameter from the assistance message and combines, for each of the k satellite signals, a common 5-bit MSB part with a corresponding individual 25-bit LSB part (step 601 ). The resulting value is exactly the same as the original k*32-bit eccentricity parameter.

The processor 114 also extracts the low-redundancy semi-major axis parameters from the assistance message and combines the common 6-bit MSB part with the corresponding individual 26-bit LSB part for each of the k satellite signals (step 602). The resulting value is exactly the same as the original k*32-bit semi-major axis parameter.

The processor 114 also extracts a time parameter from the auxiliary message, which may or may not have reduced redundancy compared to the original time parameter. Depending on the satellite system considered, the processor 114 combines the extracted common part with each of the 2*k extracted individual parts, or the extracted MSB (if any) with the extracted LSB combination (step 603). The combination includes the inversion of any change in scaling factor already performed in the base station 130 . The resulting values are exactly the same as the original k TOE/TOC parameters.

Processor 114 also extracts low redundancy SVID parameters from the auxiliary message. Depending on the satellite system considered, it converts the obtained bitmask representation into a k-bit representation. In the case where the offsets have been removed from the k original bit representations before conversion into the bitmask representation, a predetermined offset is now added again to each of the k bit representations in order to obtain the original bit counts (step 604). The result is exactly the same as the original k SVID parameters.

Processor 114 also extracts low-redundancy almanac parameters from the auxiliary message. It combines the common part with each of the individual parts (step 605). For example, if an almanac parameter is provided for Galileo and GLONASS, combine the common part indicating the week count for both with the common part indicating the week time for Galileo. This combined common part is then further combined with each individual almanac part of the corresponding Galileo satellite. In addition, the common parts of Galileo and GLONASS indicating week counts are converted into day counts and combined with the day count and time of day information in each individual almanac part of the corresponding GLONASS satellite. The resulting parameters are thus identical to the original set of almanac parameters.

The retrieved original orbit, time and SVID parameters are then used together with any other assistance data extracted from the assistance message in the conventional position calculation (step 606).

In general, it will be apparent that by removing redundancy from the parameters extracted from the navigation messages, the bandwidth required to communicate the assistance data from the base station 130 to the cellular terminal 110 can be significantly reduced. Nevertheless, the original parameters can be retrieved at the cellular terminal 110 without loss of accuracy or compatibility with the original format.

Fig. 7 provides another exemplary system according to the present invention for transmitting assistance data for AGNSS based positioning over a wireless link using reduced bandwidth.

The system includes a mobile device 720, a GNSS accessory device 710, a location server 730 of a wireless communication network, and a fixed station 740 of the wireless communication network.

Mobile device 720 includes a wireless communication component 722 . The wireless communication component 722 may be, for example, a cellular engine or a terminal, or a WLAN engine or a terminal, and the like.

The GNSS accessory device 710 includes a chip 715 and a GNSS receiver 713 linked to this chip 715 . Chip 715 may, for example, be an integrated circuit (IC) including circuitry configured to facilitate positioning. In addition to the actual assisted positioning component 719 (which may be implemented in a conventional manner), the circuit also includes an orbit parameter reconstruction component 716, a time parameter reconstruction component 717, and an SVID parameter reconstruction component 718.

Mobile device 720 and GNSS accessory device 710 include mating interfaces (not shown) that enable data exchange between the two devices via a wireless or wired link.

The fixed station 740 includes a wireless communication component 742 that allows a wireless link to be established to the wireless communication component 722 of the mobile device 720 . The wireless link may be a cellular link or a non-cellular link, such as a wireless local area network (LAN) connection.

The positioning server 730 includes a chip 735 and a GNSS receiver 733 linked to this chip 735 . Chip 735 may, for example, be an integrated circuit (IC) that includes circuitry configured to assemble assistance messages for assisted positioning. In addition to the actual assistance message assembly component 739 , the circuit also includes an orbit parameter redundancy reduction component 736 , a time parameter redundancy reduction component 737 , and an SVID parameter redundancy reduction component 738 .

The fixed station 740 and the positioning server 730 include matching interfaces (not shown) that enable direct or indirect data exchange between the two devices via wireless or wired links.

Both GNSS receivers 713, 733 are configured to receive, acquire and track signals transmitted by satellites S1, S2 belonging to one or more GNSS, including, for example, GPSL5, Galileo, GLONASS, SBAS and QZSS signals. At least GNSS receiver 733 is also configured to decode navigation messages included in such signals.

Assisted positioning operations in the system of FIG. 7 may be implemented in a manner corresponding to that described for the system of FIG. 1 with reference to FIGS. 2-6 . In this case, chip 735 is responsible for the functions of processor 134 and chip 715 is responsible for the functions of processor 114 .

The base station 130 or the network element 730 may be an exemplary electronic device according to the first aspect considered. The processor 134 or the chip 735 may be exemplary devices according to the first aspect considered. The cellular terminal 110 or the GNSS accessory 710 may be exemplary electronic devices according to the second aspect considered. The processor 114 or the chip 715 may be exemplary devices according to the second aspect considered.

The functions shown by the processor 134 executing the software 136 or the functions shown by the chip 735 can also be regarded as means for receiving parameters that have been extracted from at least one satellite signal, for removing redundancy arbitrarily from said parameters information, and means for providing parameters with reduced redundancy as assistance data for satellite signal-based positioning.

The functions shown by the processor 114 executing the software 116 or the functions shown by the chip 715 can also be regarded as means for receiving parameters as assistance data for satellite signal-based positioning (wherein the received parameters are based on signals obtained from at least one satellite signal extracted original parameters from which redundant information has been arbitrarily removed), means for reconstructing said original parameters by adding the removed redundant information to the received parameters, and for A device for using reconstructed raw parameters in assisted satellite signal-based positioning.

Furthermore, means-plus-function clauses of claim are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.

While the essential novel features of this invention have been shown, described and pointed out as applied to the preferred embodiments of the invention, it will be appreciated that those skilled in the art can modify the described apparatus and methods without departing from the spirit of the invention various omissions, substitutions and changes in form and detail. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve substantially the same results are within the scope of the invention. In addition, it should be recognized that the structures and/or elements and/or method steps shown and/or described together with any disclosed form or embodiment of the present invention can be incorporated into any other disclosed, described or suggested form or example. Just to give an example, it will be apparent that the indicated bit counts for the MSB and LSB portions as well as the indicated scale factors may be altered in any suitable manner. Furthermore, the provided embodiments can be adapted for use with any other GNSS, including future GNSS, as desired. Accordingly, it is intended that the invention be limited only by the scope of the appended claims.

Claims (15)

1. An auxiliary positioning method based on satellite signals, comprising: collecting a set of parameters for a plurality of satellites belonging to at least two different satellite systems; Included in the set of parameters is a common part for at least one parameter, wherein the common part is for each of the satellites belonging to at least one satellite system of the at least two different satellite systems valid, and wherein said common part includes a week count; In the set of parameters, for each of said satellites of said at least two different satellite systems, a respective individual part of at least one parameter is contained, wherein said individual part is only relevant to a corresponding one of said satellites one is valid, and wherein said individual portion includes at least one of: almanac data about said corresponding satellite and indirect information about said corresponding satellite; and The collected parameter set is provided for transmission in a message to the device as assistance data for assisted global navigation satellite system based positioning. 2. The method of claim 1, further comprising including in the set of parameters a satellite index for each satellite of the plurality of satellites. 3. The method according to claim 1 or 2, further comprising: including in said set of parameters a common part for at least one parameter, wherein said common part is for one of said satellites belonging to at least two different satellite systems Valid for every satellite. 4. A method according to claim 1 or 2, wherein said common part valid for each of said satellites belonging to at least one of said at least one satellite systems additionally comprises the following at least one of: week time; data release; and day count. 5. A device for assisted satellite signal-based positioning comprising a processing component, The processing component is configured to collect a set of parameters for a plurality of satellites belonging to at least two different satellite systems; The processing component is configured to include in the set of parameters a common part for at least one parameter, wherein the common part is for one of the satellites belonging to at least one satellite system of the at least two different satellite systems is valid per satellite, and wherein said common portion includes a week count; The processing component is configured to include in the set of parameters, for each of the satellites of the at least two different satellite systems, a respective individual part for at least one parameter, wherein the individual part is only for A respective one of said satellites is active, and wherein said individual portion comprises at least one of: almanac data regarding said respective satellite and indirect information concerning said respective satellite; and The processing component is configured to provide the collected parameter set for transmission to the device as assistance data for assisted satellite signal based positioning. 6. The apparatus of claim 5, wherein the processing component is configured to include in the set of parameters a satellite index for each satellite of the plurality of satellites. 7. The device according to one of claims 5 to 6, wherein said processing component is configured to include in said set of parameters a common part for at least one parameter, wherein said common part is useful for at least two Each of said satellites of a different satellite system is active. 8. Apparatus according to one of claims 5 to 6, wherein said week count is valid for each of said satellites belonging to at least two different satellite systems. 9. The device according to one of claims 5 to 6, wherein said processing component is configured to include in said set of parameters a common part for at least one parameter, wherein said common part is only relevant to said Each of said satellites of a corresponding one of at least one satellite system is active. 10. The apparatus according to claim 5 or 6, wherein said processing component is configured to: for each of said satellites belonging to at least one of said at least one satellite system The public part additionally includes at least one of the following: week time; data release; and day count. 11. Apparatus according to claim 5 or 6, wherein said processing component is configured to, at an individual portion valid only for a respective one of said satellites of at least two different satellite systems, comprise at least one of the following: day count; and day time. 12. The device of claim 11, wherein the processing component is configured to provide the assistance data for transmission via a wireless link to a wireless terminal associated with a satellite signal receiver. 13. The apparatus according to claim 5 or 6, further comprising at least one of the following: a wireless communication component configured to communicate information via a wireless link; and Satellite signal receiver. 14. The device according to claim 5 or 6, wherein the device is a base station of a cellular communication network or a positioning server. 15. An assisted positioning system based on satellite signals, comprising: equipment with processing components, The processing component is configured to collect a set of parameters for a plurality of satellites belonging to at least two different satellite systems; The processing component is configured to include in the set of parameters a common part for at least one parameter, wherein the common part is for one of the satellites belonging to at least one satellite system of the at least two different satellite systems is valid per satellite, and wherein said common portion includes a week count; The processing component is configured to include in the set of parameters, for each of the satellites of the at least two different satellite systems, a respective individual part for at least one parameter, wherein the individual part is only for A respective one of said satellites is active, and wherein said individual portion comprises at least one of: almanac data regarding said respective satellite and indirect information concerning said respective satellite; and The processing component is configured to provide the collected set of parameters for transmission to the device as assistance data for assisted satellite signal based positioning; and A device configured to use the collected set of parameters in satellite-based positioning calculations.