DE10196827T5 - Dual mode uplink / downlink position measurement and multi-protocol position measurement - Google Patents

Abstract

A method of locating a first mobile device that communicates using a first communication protocol and a second mobile device that communicates using a second communication protocol that is different from the first communication protocol, the method comprising the steps of:
a) measuring arrival times (TOAs) for signals which correspond to the first communication protocol;
b) measuring arrival times for signals which correspond to the second communication protocol;
c) calculating the position of the first mobile device based on the arrival times measured in step a); and
d) calculating the position of the second mobile device on the basis of the arrival times measured in step b).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the present invention refers to localization services. In particular relates the field of the present invention in locating a mobile device by recording the times of arrival of signals, which is between the mobile device and a plurality of transmitters or recipients, which are arranged at known positions, spread out, and on calculating a position based on the recorded Arrival times.

2. Background

Most recently, the FCC has called the introduction of localization services that radio subscribers to all localize wireless networks accurately. Two previously proposed solutions to implement such localization services are the "uplink" solution and "downlink" solution.

1 shows a conventional uplink solution where the mobile device 10 (also referred to as a "handset" or "remote terminal") that is to be located sends out a signal, such as a random access channel (RACH) burst. The arrival time (TOA); Time of arrival) of the signal is measured at each of a plurality of position measurement units (LMUs) 15-17 determined together with an associated quality indicator σ. This σ is an estimate of the standard deviation of the TOA measurement.

Each of these recorded TOA measurements and σs then becomes a mobile location center (MLC) 19 sent, which is a special processor. The MLC 19 then uses conventional algorithms, which are well known to those skilled in the art, to position the mobile device 10 based on the TOA measurements and σ determinations by the LMUs 15-17 and the known positions of the LMUs.

A suitable conventional one Localization algorithm uses a Taylor search to find the intersection to locate two or more hyperbolas. Details of such Algorithm can be found "Statistical Theory of Passive Location Systems "by D.J. Torrieri, IEEE Transactions on Aerospace and Electronic Systems, Volume AES-20, No. 2, March 1984, which is incorporated here by reference and the existing one Expertise characterizes. This algorithm locates the mobile device by he finds the intersection of two or more hyperbolas that have been determined by three or more stations. Usually becomes this type of localization algorithm on three or more TOA measurements (which are used to measure the distance from the mobile device to the To determine LMU based on the speed c of the signal), the associated σs and the known positions of each LMU.

2 shows a conventional downlink solution in which each of a plurality of base stations (BTSs) 21-23 a signal to the mobile device to be located 20 sends and the mobile device 20 determines the TOA and the σ of each of these signals. These TOA measurements and σs are then sent to the MLC 29 which implements a conventional algorithm for determining the position of the mobile device based on the TOA measurements and the σs similar to the algorithm in the uplink systems. Alternatively, if there is sufficient processing power in the handset 20 is available, the algorithm can be implemented in the handset. If the transmission frames of the DTSs 21-23 are not synchronized, the downlink algorithms are a little more complex than the uplink algorithms because the MLC must get the relative time difference between each BTS broadcast to calculate a position. This relative time information can be obtained using LMUs 25 . 26 can be obtained, which are arranged at known positions to the TOAs of the signals from the BTSs 21-23 to measure in a conventional way.

An advantage of downlink localization systems across from Uplink systems is that additional downlink handsets to one Communication network added can be without additional capacity add to the network. Another advantage of downlink systems is that the required LMU density for downlink systems is lower because downlink LMUs are only required to frame the to synchronize between the BTSs and not to perform TOA measurements of signals arriving from several handsets. Around but to implement downlink localization services need TOA measurements be carried out in the handset. Unfortunately can most handsets that are already in use (in following "conventional Handsets ") not the TOA measurements implement that for a downlink position estimate required are. As a result, you can these conventional handsets cannot be localized by a downlink system. This inability to locate the vast majority Majority of existing handsets is a major disadvantage of downlink systems.

Another disadvantage of conventional localization systems is that each conventional system only works using a single communication protocol and cannot locate handsets, the different com Use communication protocols. For example, a localization system designed to locate TDMA handsets is unable to locate handsets that communicate using GSM or AMPS. Because localization services have to be provided for all types of handsets, the conventional solution for supporting all communication protocols would include a separate localization system for each protocol and a correspondingly complex infrastructure.

In addition to the high financial Cost of deploying a separate localization service infrastructure for every Of the various technologies, it can also be costly under the aspect the public Give relationships. Some homeowners try to implement the carrier's plans Install antenna towers nearby of their houses to block. As a result, a carrier may exceed fifty thousand Have to spend dollars for a permit for to get a single antenna location and it may be that it has a have to wait a long time to the required regulatory To get approval. If for each technology separate infrastructures are installed so you come across every new installation keeps repeating these problems.

The inventors recognized a need for that Gain advantages of downlink localization services while Disadvantages of the downlink can be avoided.

The inventors also have recognized a need for handset location services to disposal that use many different communication protocols without using an unbearably expensive infrastructure.

SUMMARY PRESENTATION OF THE INVENTION

Certain aspects of the present Invention relate to combining uplink and downlink technologies into a single localization system to match that of both technologies offered benefits and many of their individual Eliminate disadvantages. Other Aspects of the Present Invention relate to combining localization services for different ones Communication protocols to a single system.

One aspect of the present invention is directed to a method of locating mobile devices, that using a first and a second communication protocol communicate. This method uses TOA measurements for signals, which correspond to the first and the second communication protocol, executed. A position of a first mobile device is determined based on the TOA measurements that for that signals corresponding to the first communication protocol are calculated, and a position of a second mobile device becomes based on the TOA measurements calculated for the second communication protocol appropriate signals executed have been. This aspect can be used with uplink systems or downlink systems be used.

Another aspect of the present The invention is directed to a device for performing multi-protocol arrival time measurements directed in connection with localization services. This facility contains one first recipient and a second receiver. The first recipient records a time of arrival of a first of one first mobile device (for uplink) and / or signal arriving from a first base station (for downlink), and outputs the recorded arrival time. The second recipient draws an arrival time of a second from a second mobile device (for uplink) and / or a second base station (for Downlink) incoming signal and outputs the arrival time. The first and second signals correspond to the first and second, respectively Communication protocol.

Another aspect of the present Invention is based on a system for determining the position of a first and a second mobile device directed using a first and a communicate second communication protocol. The system contains first and second uplink processors, each with an uplink location algorithm to implement. The system contains Moreover at least three measuring units. Each of these measurement units contains a first recipient, which records a TOA of a first signal arriving from a first mobile device and forwards this recorded TOA to the first uplink processor. Each of the measurement units contains Moreover a second recipient, the one TOA of a second signal arriving from a second mobile device records and this recorded TOA to the second uplink processor forwards. On the basis of those forwarded by the measuring units TOAs determine the position of the first and the second uplink processor of the first or second mobile device.

Another aspect of the present invention is directed to a system for determining the position of first and second mobile devices that communicate using first and second communication protocols, respectively. The system includes first and second sets of base stations that communicate with the first and second mobile devices, respectively, and first and second downlink processors, each of which implements a downlink location algorithm. The system also contains at least one measuring unit which contains a first and a second receiver, the respective arrival times (TOAs) of first and second signals, respectively, of the first or two sets of base stations arrive. These receivers forward the recorded arrival times (TOAs) to the first or second downlink processors. The first downlink processor determines the position of the first mobile device using the downlink localization algorithm on the basis of the arrival times (TOAs) forwarded by the at least one measuring unit and the arrival times recorded by the first mobile device. The second downlink processor determines the position of the second mobile device using the downlink localization algorithm on the basis of the arrival times forwarded by the at least one measuring unit and the arrival times recorded by the second mobile device.

BRIEF DESCRIPTION OF THE DRAWINGS

1 Figure 3 is a schematic illustration of a known uplink location system.

2 is a schematic illustration of a known downlink localization system.

3 Figure 3 is a schematic illustration of a dual mode uplink / downlink location system in accordance with the present invention.

4A FIG. 10 is a schematic illustration of a first type of LMU associated with the embodiment of FIG 3 can be used.

4B Figure 11 is a schematic illustration of the first type of LMU that has been modified to support multiple wireless communication protocols.

5A FIG. 10 is a schematic illustration of a second type of LMU used in connection with the embodiment of FIG 3 can be used.

5B Figure 11 is a schematic illustration of the second type of LMU that has been modified to support multiple wireless communication protocols.

6 Figure 11 is a schematic illustration of how data from uplink measurements and downlink measurements can be combined to form a position estimate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

3 illustrates a system in which a mobile device 30 (e.g., a cell phone) can be located using either an uplink or a downlink solution. In 3 the signal flow in the uplink mode is identified with a prefix "U:" and the signal flow in the downlink mode is identified with a prefix "D:". The signals can be communicated between the various system components using any desired communication standard (including, for example, ANSI-136 TDMA, AMPS, GSM, SGM 900, DCS 1800, PDC, PCS 1900, iDEN, etc.).

The system is based on a set of at least three dual-purpose LMUs 35-37 which the TOA from from the mobile device 30 incoming signals as well as from the base stations 31-33 can measure incoming signals. These LMUs 35-37 are preferably permanently connected to the earth at known reference positions, but can also be temporarily fixed in their position (for example on a truck at a known reference location). It should be noted that although only three BTSs 31-37 and three LMUs 35-37 A greater number of BTSs and LMUs (e.g., seven) can be used to provide improved accuracy, as will be apparent to those skilled in the art.

To the mobile device 30 To locate using the uplink solution, each of the LMUs listens 35-37 after a signal from the mobile device 30 , such as a Random Access Channel (RACH) burst. When the signal from the mobile device 30 arrives, each of the LMUs determines 35-37 the TOA of the incoming signal together with an associated quality indicator (σ). A global positioning satellite (GPS) based time reference can be used at each LMU to synchronize each TOA measurement with a common frame of the reference. Each LMU then forwards its TOA measurement and its σ to an MLC 39 using an appropriate communication link (e.g., a hardwired or wireless communication link). The MLC 39 contains an uplink processor 39A , which is programmed to implement a conventional uplink location algorithm. After receiving the TOA measurements (and the associated σs) from each of the LMUs 35-37 implements the MLC 39 the uplink algorithm to the position of the mobile device 30 based on the received TOA measurements and σs as well as the known positions of the LMUs.

To the mobile device 30 To locate using the downlink solution, the system includes that each of at least three BTSs 31-33 a signal (for example, a broadcast control channel (BCCH) signal; broadcast control channel signal) to the mobile device 30 sends. If the signals from the BTSs 31-33 the mobile device determines 30 the TOA of the incoming signals together with associated quality indicators (σ) for each incoming signal. The mobile device 30 then forwards the TOA information to the MLC 39 further, preferably over the same wireless network that used to with the mobile device 30 to communicate. The MLC 39 contains a downlink processor 39B , which is programmed to implement a conventional downlink localization algorithm. During the uplink processor 39A and the downlink processor 39B as two different blocks are illustrated, they can actually be integrated together by running different algorithms on a single processor.

In the meantime, each of the LMUs is listening 35-37 after from the BTSs 31-33 sent signals. When an LMU receives a signal from a BTS, the LMU determines 35-37 the arrival time of the incoming signal. This type of TOA measurement (in which an LMU measures the arrival time of a signal from a BTS) is referred to here as TOA *. Each LMU then forwards the TOA * information to the MLC 39 using an appropriate communication link (e.g., a hardwired or wireless communication link). This communication link can operate using the same protocol as the handset being located (for example, an AMPS communication link could be used if an AMPS protocol handset is located). The TOA * measurements enable the MLC 39 , any real time differences between the transmission frames of the different BTSs 31-33 to compensate. The MLC 39 then determines the position of the mobile device 30 using the downlink algorithm based on the TOA measurements and the σs from the mobile device 30 received by the LMUs 35-37 received TOA * measurements and the known positions of the LMUs and BTSs.

4A Figure 3 is a schematic illustration of a dual mode uplink / downlink LMU 40A who as one of the LMUs 35-37 in the embodiment of the 3 can be used. The LMU 40A contains an antenna interface 42 which interface to one or more receiving antennas 41 forms. It also contains an uplink receiver 43 , which is designed to receive signals arriving from the mobile devices to be located (such as RACH bursts), and a downlink receiver 44 , which is designed to receive incoming signals from a BTS (such as BCCH signals). A communication link 46 which is an interface between the LMU 40A and a remote MLC (not shown) is also provided. Operation of the LMU is preferred 40A from a control device 45 controlled.

Signals arriving from both the mobile devices and BTSs are from the antennas 41 caught and by the right recipient 43 (for signals from mobile devices) and 44 (for base station signals) received. The uplink receiver 43 and the downlink receiver 44 cooperate with the control facility 45 so that they record the arrival time of the respective incoming signals. The detection of when a signal is sent to the uplink receiver 43 Arrived from a mobile device can be performed using conventional uplink control techniques. Similarly, the detection of when a signal is sent to the downlink receiver 44 arrived from a BTS, using conventional downlink control techniques. Optionally, the control device 45 rely on digital signal processing (DSP) to implement these control functions.

As soon as a TOA has been determined for the incoming signal, the control device directs 45 the determined TOAs to a remote mobile location center (MLC) over a communication link 46 further. This communication link 46 can be implemented using any suitable technique, including, for example, wired interfaces (e.g., over standard telephone lines) as well as wireless interfaces (e.g., over the same network used to communicate with the mobile device).

In uplink mode, the TOA measurements performed by the system must be matched against a common reference frame so that the MLC can form an accurate position estimate. A suitable way of providing such a common frame of reference is to use a Global Positioning Satellite (GPS) receiver 47 in every LMU 40A and to relate each TOA measurement reported to the MLC to a received GPS time.

4B Figure 3 is a schematic illustration of another dual mode uplink / downlink LMU 40B who as one of the LMUs 35-37 in the embodiment according to 3 can be used. This LMU 0B enables the exemplary embodiment 3 To locate handsets that communicate using various wireless communication protocols (such as ANSI-136 TDMA, GSM, AMPS, etc.), rather than being limited to a single communication protocol. The LMU 40B is similar to the LMU 40A (in the 4A with the exception that the LMU 40B a plurality of uplink receivers 43A-43C , a plurality of downlink receivers 44A-44C and a plurality of communication links 46A-46C (instead of an uplink receiver, a downlink receiver and a communication link). Each of the uplink receivers is preferably each 43A-43C dedicated to a special wireless communication protocol, and each of the downlink receivers 44A-44C is a specific wireless communication dedicated to protocol. Of course, although three uplink receivers and three downlink receivers are illustrated, a different number of receivers can instead be used to accommodate any number of different wireless communication protocols.

Preferably each is the recipient 43A-43C . 44A-44C implemented on a single circuit board that plugs into a common backplane and under the control of a common controller 45 can be operated. This arrangement allows each LMU to work for as many different wireless communication protocols as is desired by inserting additional receivers. Optionally, a separate communication link can be made for each wireless communication protocol 46A-46C be included. If separate communication links are provided, the same wireless network used to communicate with each handset can be used to forward the TOA measurements for that communication protocol to a remote MLC (e.g., an AMPS communication link for an AMPS handset and a GSM communication link for a GSM handset). A separate MLC can then be used for each protocol to implement the localization algorithms. If a single communication link is used for all different communication protocols, a separate MLC can be used for each protocol or a common MLC can be used for two or more communication protocols.

This arrangement, in which an LMU can perform TOA measurements for different communication protocols, can be extended to uplink only systems and downlink only systems. For only uplink systems, the block representation would 4B be similar, but the downlink receiver 44A-44C would fall away. For only downlink systems, the block representation would 4B be similar, but the uplink receiver 43A-43C would be left out. Suitable modifications to the control device 45 should also be done so that the controller does not expect TOA measurements from a nonexistent source.

5A Figure 3 is a schematic illustration of another dual mode uplink / downlink LMU 50A who as one of the LMUs 35-37 in the embodiment according to 3 can be used. This LMU 50A contains an antenna interface 52 which interface to one or more receiving antennas 51 forms, and a combination uplink / downlink receiver 53 which is designed to receive incoming signals (such as RACH bursts) from the mobile devices to be located and incoming signals (such as BCCH signals) from a BTS. A communication link 56 which is an interface between the LMU 50A to a remote MLC (not shown) and an optional GPS receiver 57 are also provided. Operation of the LMU is preferred 50A from a control device 55 controlled. The operation of the embodiment according to 5A is similar to the operation of the embodiment described above 4A with the exception that instead of separate uplink and downlink receivers ( 43 and 44 , shown in 4A ) a single uplink / downlink receiver 53 is used.

5B Figure 3 is a schematic illustration of another dual mode uplink / downlink LMU 50B who as one of the LMUs 35-37 in the embodiment according to 3 can be used. This LMU 50B allows according to the embodiment 3 To locate handsets that communicate using various wireless communication protocols (such as MDTA, GSM, AMPS, etc.), rather than being limited to a single communication protocol. The operation of this LMU 50B is similar to the way the LMU operates 40B (in the 4B with the exception that an integrated uplink / downlink receiver is used for each communication protocol instead of separate uplink receiver and downlink receiver for each communication protocol.

Implementing both downlink and uplink algorithms in a single system enables the system to take advantage of the advantages of the downlink while avoiding the downlink's disadvantages. In particular, the dual mode localization uplink / downlink system described herein enables a system operator to add downlink handsets to a communications network without adding additional capacity to the network by locating these handsets using the downlink mode. In addition, the uplink / downlink system described here can be used to localize conventional handsets (legacy handsets) that do not support downlink mode. When a location estimate is required for one of these conventional handsets, the system switches to uplink mode and processes the signals arriving from the handsets to determine the position of the handset. By using the downlink mode as the default localization mode and switching to the uplink mode only for handsets that do not support the downlink mode, the amount of new network capacity that needs to be added can be kept to a minimum. Preferably, new handsets added to the wireless network support downlink mode to take advantage of that from the downlink Advantages.

The most popular conventional localization algorithms work by intersecting two or more hyperbolas find each hyperbola by a pair of TOA measurements is determined. In a single mode system there are at least three TOA measurements required to obtain two pairs of TOA measurements (e.g. can the pairs AB and AC from three measurements A, B and C) are formed. If in a single mode system only one pair of TOA measurements for disposal no position estimate can be made become.

However, if a dual mode system is available, a first hyperbola can be obtained from a pair of TOA measurements made using the uplink mode and a second hyperbola can be obtained from a pair of TOA measurements taken below Using the downlink mode have been performed. The intersection of these two hyperbolas can then be used as an estimate of the position of the mobile device. This is in 6 illustrates the first hyperbola 68 using the uplink mode based on the TOA measurements of the signal from a handset 60 that at each of the LMUs 65 . 66 arrives, was won. A second hyperbole 69 is obtained using the downlink mode based on the TOA measurements of the signals from the BTSs 61 . 62 on the handset 60 arrive, and the TOA * measurements of the signals from the BTSs 51 . 62 working at each of the LMUs 65 . 66 arrive. The intersection of the hyperbolas 68 . 69 is used as a position estimate. Providing a position estimate based on an uplink hyperbole 68 and a downlink hyperbola 69 could make the difference between getting an accurate position estimate and not being able to win if two hyperbolas cannot be obtained using a single connection direction. In addition, even if two hyperbolas from a single connection direction (i.e., uplink or downlink) are available, the additional hyperbolas obtained by relying on both technologies at the same time can be used to increase the accuracy of the resulting position estimate improve.

The provision of a dual mode uplink / downlink localization system in accordance with the embodiments described above can about it the wrangling between the various players in the industry of wireless connections decrease by both localization architectures supported at the same time become. It can about that also making it available more quickly the localization services the public support, by ensuring that investments into the infrastructure for one of the two technologies is not in vain.

By adding multiple communication technologies can be combined in a single box, the number of new ones Antenna places that are required to implement localization services, be minimized. This arrangement should therefore be the resistance the public against the installation of the necessary infrastructure.

While the present invention in the context of the preferred described above embodiments explained has been, it is clear that various changes on these embodiments can be made and that different equivalents can be used instead without departing from the spirit or scope of the invention, as those of ordinary skill in the art becomes clear.

Summary

Certain aspects of the disclosure relate to combining uplink and downlink localization technologies into a single localization service system to gain the advantages of each of the technologies while eliminating many of their individual disadvantages. Mobile devices that support a downlink can then be located using the downlink mode, and mobile devices that do not support a downlink can be located using the uplink mode. A mobile device can even be located based on a combination of uplink measurements and downlink measurements. Other aspects of the disclosure relate to providing a single location service system for locating mobile devices that communicate using a variety of different communication protocols.
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Claims (18)

A method of locating a first mobile device communicating using a first communication protocol and a second mobile device communicating using a second communication protocol different from the first communication protocol, the method comprising the steps of: a) measuring Arrival times (TOAs) for signals that correspond to the first communication protocol; b) measuring arrival times for signals which correspond to the second communication protocol; c) calculating the position of the first mobile device based on the arrival times measured in step a); and d) calculating the position of the second mobile device based on that measured in step b) Arrival times. The method of claim 1, wherein the first communication protocol a Time Division Multiple Access (TDMA) and the second communication protocol a global system for is mobile communication (GSM). The method of claim 1, wherein the first Communication protocol corresponding signals include signals from a first mobile device resulting and at least three measuring units arrive, and those corresponding to the second communication protocol Signals include signals originating from a second mobile device and arrive at the at least three measuring units. The method of claim 1, wherein the first Communication protocol corresponding signals include signals which result from a first set of at least three base stations and in the at least one measuring unit arrive, and those corresponding to the second communication protocol Signals include signals that consist of a second set of at least come from three base stations and in the at least one measuring unit arrive. A facility for performing multi-protocol arrival time measurements in conjunction with localization services, the facility having: a first recipient, one of the arrival times of a first mobile device and / or records a first base station arriving first signal and outputs the recorded arrival time of the first signal, the first signal corresponding to a first communication protocol, and a second recipient, one of the arrival times of a second mobile device and / or records a second base station arriving second signal and outputs the recorded arrival time of the second signal, wherein the second signal corresponds to a second communication protocol. The device of claim 5, wherein the first receiver the arrival time of the first signal arriving from the first mobile device records and the second recipient the arrival time of the second signal arriving from the second mobile device records. The device of claim 5, wherein the first receiver the arrival time of the first arriving from the first base station Signals records and the second receiver the arrival time of the of the second base station arriving second signal. The device of claim 5, wherein the first Communication protocol a "Time Multiple Access Division (TDMA) and the second communication protocol is a global system for mobile Communication (GSM) is. The device of claim 5, wherein the first receiver and the second receiver are integrated. The device of claim 5, wherein the first receiver and the second receiver are separated. A system for determining the position of a first mobile device, that communicates using a first communication protocol, and a second mobile device, that communicates using a second communication protocol, the system comprising: a first uplink processor that implements an uplink location algorithm; one second uplink processor that uses an uplink location algorithm implemented; at least three measuring units, each of the measuring units (a) a first recipient, which is an arrival time of an arrival time from a first mobile device records the first signal and the recorded arrival time of the forwards the first signal to the first uplink processor, wherein the first signal corresponds to the first communication protocol, and (b) a second receiver, which is an arrival time of an arrival time from a second mobile device second signal and the recorded arrival time forwards the second signal to the second uplink processor, the second signal corresponding to the second communication protocol, contains in which the first uplink processor under the position of the first mobile device Use the uplink location algorithm based on the forwarded to the first uplink processor by the measuring units Arrival times are determined and the second uplink processor determines the position of the second mobile device based on using the uplink location algorithm those forwarded to the second uplink processor by the measuring units Arrival times determined. The system of claim 11, wherein the measuring units the recorded arrival times of the first signal to the first Uplink processor via a Forward communication link that the first communication protocol used, and the measuring units the recorded arrival times of the second signal to the second Uplink processor via forward a communication link that uses the second communication protocol used. The system of claim 11, wherein the first communication protocol is "Time Division Multiple Access" (TDMA) and the second communication protocol is a global system for mobile communication (GSM). The system of claim 11, wherein the first uplink processor and the second uplink processors are the same processor. A system for determining the position of a first mobile device, that communicates using a first communication protocol, and a second mobile device, that communicates using a second communication protocol, the system comprising: a first sentence of at least three base stations with the first mobile device under Communicate using the first communication protocol; one first downlink processor using a downlink localization algorithm implemented; a second set of at least three base stations, the one with the second mobile device communicate using the second communication protocol; one second downlink processor that uses a downlink localization algorithm implemented; and at least one measuring unit with (a) a first receiver, the Arrival times of those arriving from the first set of base stations first signals recorded and the recorded arrival times forwards the first signals to the first downlink processor, the first signals corresponding to the first communication protocol, and (b) a second receiver, the arrival times of second ones arriving from the second set of base stations Signals and the recorded arrival times of the forwards second signals to the second downlink processor, the second signals corresponding to the second communication protocol, in which the first downlink processor below the position of the first mobile device Using the downlink localization algorithm on the basis to the first downlink processor by the at least one measuring unit forwarded arrival times and the arrival times recorded by the first mobile device and the second downlink processor determines the position of the second mobile device using the downlink localization algorithm on the Basis of the at least to the second downlink processor a measuring unit forwarded arrival times and those of the second mobile Device recorded Arrival times determined. The system of claim 15, wherein the at least a measuring unit the recorded arrival times of the first signal to the first downlink processor via a Forwarding communication link that the first communication protocol used, and the at least one measuring unit the recorded Arrival times of the second signal to the second downlink processor via a Forwarding communication link that the second communication protocol used. The system of claim 15, wherein the first communication protocol is "Time Division Multiple Access "(TDMA) and the second communication protocol is a global system for mobile Communication (GSM) is. The system of claim 15, wherein the first downlink processor and the second downlink processor is the same processor.