DE102005010888A1 - Mobile unit position determination arrangement, especially for a GPS- equipped unit, e.g. for use in a road toll system, makes use of pseudo-range data to reduce the amount of data that has to be transferred to a back office system - Google Patents

Abstract

Arrangement for determining the position of a mobile unit, has at least a mobile unit with an interface to a back office data processing unit. The back office unit has means for calculating the position of the mobile unit using pseudo-range data. An independent claim is made for a system for determining the position of a mobile unit, whereby the mobile unit is configured to transfer a pseudo-range measurement to the back office, which then calculates the position of the mobile unit based on the pseudo- range data.

Description

The The present invention relates to a method and an arrangement for determining the position of a mobile device.

Starting situation and problem

When Starting situation, many mobile devices are considered, which for the position determination be used. These devices are characterized by the fact that they all receive signals from a GPS receiver certain satellites and are able to receive the current Position based on GPS signals.

Of the The entire algorithm for calculating the position is located here completely in the mobile devices.

• 1. Timestamp
• 2. Latitude (WGS84)
• 3. Longitude (WGS84)
• 4. HDOP (Horizontal Dilution of Precision)
• 5. Valid GPS-Fix
• 6. Course
• 7. Speed
• 8. Anzahl der Satelliten

If the calculated position data must be provided for a third party application, such as for navigation systems or GPS based toll systems, then at least the following data is needed for a single fix to determine the exact position of a moving vehicle:

• 1st Timestamp
• 2. Latitude (WGS84)
• 3. Longitude (WGS84)
• 4. HDOP (Horizontal Dilution of Precision)
• 5. Valid GPS fix
• 6. Course
• 7. Speed
• 8. Number of satellites

Consists the requirement of a possible error-free positioning, then have GPS fixes almost every second to be available. Only then can it be guaranteed that at complex roadways (e.g. Parallel roads, many underpasses and overpasses at motorway junctions) the currently used road is determined. An essential Factor for this is also the inaccuracy of the position determination.

By This requirement is currently generating large amounts of data in a very short time. additionally is determined by the usually every second position calculation a high level of Processor power needed, what a higher Energy consumption leads. This can be especially true of mobile and not with a permanent one Power connection equipped devices to restrictions of the operating time to lead.

• 1. Im mobilen Gerät Wird die benötigte Applikation im mobilen Gerät betrieben, dann werden die Positionen sofort durch die Anwendung übernommen und entsprechend weiterverarbeitet. Das Ergebnis sind schließlich applikationsabhängige Informationen, wodurch die ursprünglichen, auf GPS basierenden Positionsinformationen verloren gehen. Müssen die Daten für eine weitere Verarbeitung in ein Back Office übertragen werden, kann jedoch somit eine starke Datenreduktion erreicht werden – mit dem großen Nachteil, dass die Verifizierung der Applikationsdaten im Nachhinein nicht mehr oder nur bedingt möglich ist.
• 2. Im Back Office Alle auf GPS basierenden Positionsdaten können aber auch direkt in ein Back Office übertragen werden. Diese Art der Datenbehandlung macht in der Regel nur dann Sinn, wenn die Daten nicht sofort vor Ort benötigt werden (vgl. GPS basierte Mautsysteme, Flottenmanagementsysteme, Positionsbestimmung für Sicherheitsdienste), sondern sowieso einer Nachbearbeitung bedürfen. Der große Vorteil dieser Methode liegt darin, dass die GPS (Roh-)Daten zur wiederholten Nachbearbeitung vorhanden sind. Der große Nachteil dieser Methode ist jedoch, dass die oben erwähnten GPS-Informationen ein hohes zu übertragende Datenvolumen aufweisen. Aufgrund der derzeitigen Übertragungsmöglichkeiten, die flächendeckend zur Verfügung stehen, (GSM, GPRS, UMTS, usw.) ist mit hohen Übertragungskosten zu rechnen, die bei einer sehr großen Anzahl an mobilen Geräten in einen unwirtschaftlichen Bereich geraten können. Das hier beschriebene Verfahren richtet sich insbesondere auf diesen Anwendungsfall.

For all applications that evaluate the obtained position data, there are two possible execution locations:

• 1. In the mobile device If the required application is operated in the mobile device, the positions are immediately adopted by the application and further processed accordingly. Eventually, the result is application-dependent information, which destroys the original GPS-based position information. However, if the data has to be transferred to a back office for further processing, then a considerable reduction in data can be achieved - with the great disadvantage that the verification of the application data is subsequently no longer possible or only possible to a limited extent.
• 2. In the back office All GPS-based position data can also be transferred directly to a back office. This type of data treatment usually makes sense only if the data is not needed immediately on site (see GPS based toll collection systems, fleet management systems, positioning for security services), but anyway requires further processing. The big advantage of this method is that the GPS (raw) data is available for repeated post-processing. The big disadvantage of this method, however, is that the GPS information mentioned above has a high data volume to be transmitted. Due to the current transmission possibilities that are available nationwide (GSM, GPRS, UMTS, etc.) high transmission costs can be expected, which can be uneconomical for a very large number of mobile devices. The method described here is directed in particular to this application.

Around the position determination in the back office even with a very large number from mobile devices with low transfer volume and costs but much higher To be able to control the accuracy of the position determination the method and the arrangement according to the present invention developed.

The present invention can be described as follows:
Arrangement for determining the position of a mobile device, comprising at least one mobile device that interfaces with a back office, with a back office that interfaces with the at least one mobile device, and with means for calculating the position of the mobile device based on Pseudo range data, which is provided in the back office.

Method for determining the position of a mobile device, characterized by the following steps:
a mobile device transmits pseudo range data to a back office;
In the back office, the location of the mobile device is calculated based on the "pseudo range" data.

characteristics and details associated with the method of the invention are described, also in connection with the inventive arrangement apply, and vice versa.

The present invention can also be summarized as follows:
An essential requirement is a mobile device with a GPS receiver, processor unit, memory and a communication unit (GSM, GPRS, UMTS). The new method is characterized in that the calculation of the data listed above is not performed in the mobile device. Instead, only the data from a so-called pseudo-range measurement are collected and transferred to a back office. The actual location calculation then takes place completely in the back office. The evaluation of the position locally in the mobile device may or may not be done and serves as input to the logic for controlling the data acquisition and transmission in the mobile device.

The "pseudo range" data

For the calculation The exact position data in the back office are the following on a "pseudo-range" measurement raw data collected per fix from the GPS receiver.

From speaks of a "pseudo-range" measurement one, if one has the signal transit times compared to a receiver clock measures that is not synchronized with the transmitter clocks.

The "pseudo ranges", ie the apparent ones Distances result from the product of "pseudo" time and propagation speed the signal. From the actual Distances differ only by a distance, which depends on the time difference exhibited by the transmitter and receiver clocks.

For the position determination Therefore, instead of the absolute time difference, the "pseudo" time difference is used.

The Use of the "pseudo-range" measurement is therefore characterized in that their use in a higher achievable resolution of the measuring system results.

• 1. Zeitstempel1 (GPS Woche z.B.: 1024) [1024-4096]
• 2. Zeitstempel2 (GPS Zeit in der Woche z.B. 5.7947649743e+005 ms) [0-604800000]
• 3. SAT id1 (PRN z.B. 31) [1-32]
• 4. SAT pseudorange1 (z.B. 3.9839250480e+007) [0 – 10^9]
• 5. SAT Quality1 (z.B. 35) [0-60]
• 6. SAT id12 (PRN .z.B 5) [1-32]
• 7. SAT pseudorange12 (z.B. 4.0913762016e+007) [0 – 10^9]
• 8. SAT Quality2 (z.B. 51) [0-60]

Therefore, if the following data is collected from a "pseudo-range" measurement for a fix, then a very accurate location determination can be made at any later time, whereby the amount of data collected will be substantially less than the collection of values due to the smaller value ranges per parameter GPS coordinates:

• 1st timestamp1 (GPS week eg: 1024) [1024-4096]
• 2. Timestamp2 (GPS time in the week eg 5.7947649743e + 005 ms) [0-604800000]
• 3. SAT id1 (PRN eg 31) [1-32]
• 4. SAT pseudorange1 (eg 3.9839250480e + 007) [0 - 10 ^ 9]
• 5. SAT Quality1 (eg 35) [0-60]
• 6. SAT id12 (PRN .zB 5) [1-32]
• 7. SAT pseudorange12 (eg 4.0913762016e + 007) [0 - 10 ^ 9]
• 8. SAT Quality2 (eg 51) [0-60]

At It should be noted that a GPS receiver has a maximum of 12 satellites can "see" at a time, causing the Data structure can also be reduced to 12 satellites.

There usually no online transmission If the data in the BackOffice is necessary, the data can be stored in a memory of the mobile device be cached. Depending on the application and memory size then the collected data at specific times and / or defined Transmit thresholds to the back office.

To successful transmission the data, can these in the mobile device deleted again become.

optimizations

The mentioned above Data structure can be further optimized in several stages:

A) Utilization of the max. Range of values and distribution of the data per fix to individual byte structures:

Example:

B) Generation of a dynamic Data structure per fix

In the majority of cases, signals from 12 satellites are not always received. Due to this fact, the data structure can be designed in such a way that only the data of the "visible" satellites are stored at all times, by inserting an additional field indicating the number of following satellite structures:

C) compression of the data through established algorithms

The accumulated data volume may be before transfer to the back office further reduced by the use of established compression algorithms become.

D) reduction redundant information

redundant Information or information with high memory requirements in the collected data can also be further reduced. This can be done by the same information only once in a parent level to generating telegram structure (see GPS week / timestamp1) and secondly, that numbers with large value ranges (see TOW / Zeitstempel2) and relatively small deviations to subsequent values as well only once in a parent Just be written. Pro record can then only a delta information with a small value range (1-2 bytes) to the reference value listed become.

E) Reduction of fixed distances

Thereby, that by the "pseudo-range" measurement in hindsight very accurate location determinations can be performed the number of fixes to be stored is greatly reduced (e.g. to a 10 second interval or dynamically depending on the direction of travel change). Using mathematical approximation methods (eg spline approximation) with enough huge Number of "pseudo-range" measuring points, can subsequently a replica of the completed Distance to be calculated.

transmission

• – ID des mobilen Gerätes
• – Telegramm-Typ zur eindeutigen Erkennung der folgenden Nutzdaten
• – Telegram-Version zur eindeutigen Erkennung der verwendeten Datenstrukturen

Each time the collected data has to be transferred to the back office, the data must be packed into a defined frame structure. In order to ensure a clear assignment to the mobile device in the back office, certain additional information about the hader is needed. These include, among others

• - ID of the mobile device
• - Telegram type for unambiguous identification of the following user data
• - Telegram version for unambiguous recognition of the data structures used

Depending on used transmission protocol can even more information needed which are, however, primary depend on the particular application.

reference station

Around the calculation of the position data on a very high accuracy guarantee to be able to several reference data needed. You can do this on the one hand, other mobile devices which also provide data for approximately the same time period, or there will be some reference stations over the area considered Installed.

The Functions of these reference stations are identical to those of the mobile devices: it will be about "pseudo-range" measurements data collected and sent to the back office. The only difference is that the data is transmitted permanently be in order for a mobile device always to have a suitable reference. This usually is because of economical reasons be more useful, the data about to transfer a leased line to the back office instead of an air interface to use.

Calculation of the position in the back office

The Data from the mobile devices and from the reference stations, the formation of simple and / or double differences on the positions of the mobile devices to the respective one Time t closed. This procedure makes it possible to do a lot higher Accuracy (up to one order of magnitude: i.e. from an average of 10 meters to 1 meter) of positions the mobile devices to calculate.

Of the Advantage of this evaluation is that by the essential higher Accuracy in the back-office finishing with essential small amounts of data (i.e., fewer locations) from the mobile devices. This can be both transmission costs as well as power consumption of the devices achieve proportional improvement in accuracy.

system Design

The structure of an advantageous system is in the 1 shown.

As already mentioned, Collect mobile devices Measured values for the position determination through the use of "pseudo-ranges", reference stations and making single and / or double differences.

optional can additionally one or more reference stations are operated.

in the Back Office, the data is then collected and the calculation the GPS positioning is triggered.

The obtained position data can then via services be further "refined" by the Data for certain uses are used.

Claims (2)

Arrangement for determining the position of a mobile device, with at least one mobile device, which has an interface to a back office, with a Back Office, which is an interface to the at least one mobile Device, and means for calculating the position of the mobile device based on "pseudo range "data, where These funds are provided in the back office. Method for determining the position of a mobile device, characterized by the following steps: from a mobile device Data of a "pseudo range "measurement transfer a back office; in the Back Office becomes the position based on the "pseudo range" data of the mobile device calculated.