Location tracing system for mobile telecommunication terminal and method thereof

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a mobile telecommunication terminal, and more particularly to a system and method for tracing a location of the terminal in a service area.

[0003] 2. Background of the Related Art

[0004] One conventional system for tracing the location of a mobile telecommunication terminal involves mounting a global positioning system (GPS) receiver in the terminal and then determing location by analyzing a signal received from a low-earth-orbit satellite. A second conventional system traces the location of a terminal using a network of a wireless telecommunication system. These methods will now be explained.

[0005]FIG. 1 shows the first conventional system, which traces the location of a mobile telecommunication terminal by analyzing a signal from a low-earth-orbit satellite. This system includes a satellite receiving unit <b>10</b> which receives satellite signals transmitted from a plurality of universal GPS satellites (1˜N). Location information included in the received signals and time deviations of the received signals, are then used to trace the location of the terminal. In this system, the GPS satellites (1˜N) and the satellite receiving unit <b>10</b> require a substantial amount of locking time at first. Also, sending/receiving of the satellite signal is disturbed by adjacent architectures and a receiving sensitivity of the satellite signal is very weak. Accordingly, a location of the mobile telecommunication terminal is inaccurately recognized and much cost is required.

[0006]FIG. 2 shows the second conventional system, which traces the location of the mobile telecommunication terminal using a network of a wireless telecommunication system. This sytem includes a plurality of base stations <b>22</b>-<b>1</b>, <b>22</b>-<b>2</b>, . . . <b>22</b>-<i>n </i>which receive a predetermined signal transmitted from the mobile telecommunication terminal <b>21</b>. A location calculation unit <b>23</b> then calculates a location of the terminal using location information according to the predetermined signal from the plurality of base stations and reception time deviation between the received signals. The calculated result is provided to the mobile telecommunication terminal <b>21</b>.

[0007] The second conventional system described above performs location tracing based on a distance difference between the mobile telecommunication terminal <b>21</b> and the base stations <b>22</b>-<b>1</b>, <b>22</b>-<b>2</b>, . . . <b>22</b>-<i>n. </i>As a result, a base station located far from the terminal has difficulty in receiving a signal necessary to calculate a location, since the base station has a weak receiving sensitivity for the signal transmitted from the terminal. In order to solve this problem, it has been proposed to increase a strength for transmittance force of the corresponding terminal. However, it has been shown that a terminal having an increased transmittance force does not easily recognize the signal transmitted from a base station located far from the terminal. That is, in the second conventional system for tracing a location of the mobile telecommunication terminal using a network of a wireless telecommunication system, even if the GPS receiver does not have to be mounted in the mobile telecommunication terminal, an error range for a location of the terminal is substantial.

SUMMARY OF THE INVENTION

[0008] An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

[0009] An object of the present invention is to provide a system and method for tracing the location of a mobile telecommunication terminal by calculating distances between the terminal and base stations based on delayed time for receiving a predetermined signal transmitted from the terminal to the base stations.

[0010] It is another object of the present invention to provide the base stations with distance calculation algorithm processing units which calculate distances between the base stations and the mobile telecommunication terminal.

[0011] To achieve these and other objects and advantages, the present invention provides a location tracing system for a mobile telecommunication terminal comprising: mobile telecommunication terminals for transmitting predetermined signals including their discrimination information with predetermined intervals; a plurality of base stations for calculating distances from the mobile telecommunication terminals on the basis of reception time for the predetermined signals transmitted from the mobile telecommunication terminals and then transmitting the distance values; and a cell controller for tracing locations of the mobile telecommunication terminals by using the distance values transmitted from the plurality of base stations. Herein, the cell controller sets/stores location information corresponding to the respective distance values in a table in advance and certifies the location information by the table, thereby determining regions which are the most similar to locations of the mobile telecommunication terminals.

[0012] The present invention is also a method for tracing locations of the mobile telecommunication terminals comprising: dividing a region around the base stations, calculating distances between mobile telecommunication terminals located at the divided regions and each base station, and setting/storing the distance values and location information by the distance values in a table of a cell controller in advance; receiving discrimination information transmitted from the mobile telecommunication terminals and calculating distances between the mobile telecommunication terminals and the respective base stations on the basis of delayed time for receiving the discrimination information; transmitting the calculated distance values to the cell controller; and discriminating location information corresponding to the distance values between the mobile telecommunication terminals and the respective base stations transmitted from the respective base stations by the table of the cell controller, thereby tracing locations of the mobile telecommunication terminals.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a diagram showing a construction of a first system for tracing a location of a mobile telecommunication terminal by analyzing a satellite signal according to a conventional low earth orbit satellite;

[0014]FIG. 2 is a diagram showing a construction of a second system for tracing a location of a mobile telecommunication terminal by using a network of a conventional wireless telecommunication system;

[0015]FIG. 3 is a diagram showing a location tracing system for a mobile telecommunication terminal according to one embodiment of the present invention;

[0016]FIG. 4 is a diagram indicating how a distance calculation maybe perfomed between a base station and a mobile telecommunication terminal based on a delayed time of a predetermined signal transmitted from the mobile telecommunication terminal; and

[0017]FIG. 5 is a diagram explaining a location tracing method for a mobile telecommunication terminal according to an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018]FIG. 3 is a diagram showing a system for tracing a location of a mobile telecommunication terminal according to one embodiment of the present invention. This system includes mobile telecommunication terminals <b>31</b>, <b>32</b>, and <b>33</b>, base stations <b>41</b>, <b>42</b>, and <b>43</b>, and a cell controller <b>51</b>. The mobile telecommunication terminals transmit predetermined signals including discrimination information with a predetermined interval. The base stations calculate distance values from the mobile telecommunication terminals based on times for receiving the predetermined signals transmitted from the mobile telecommunication terminals. The base stations then transmit the distance values. The cell controller traces locations of the mobile telecommunication terminals using the distance values transmitted from the plurality of base stations. In this system, the base stations are provided with distance-calculation algorithm processing units <b>41</b>A, <b>42</b>A, and <b>43</b>A which calculate respective distances from the mobile telecommunication terminals <b>31</b>, <b>32</b>, and <b>33</b>.

[0019] Operations of the location tracing system of the present invention will now be explained. First, the respective mobile telecommunication terminals <b>31</b>, <b>32</b>, and <b>33</b> transmit predetermined signals including their discrimination information to the base stations <b>41</b>, <b>42</b>, and <b>43</b> with predetermined intervals.

[0020] Then, for each terminal <b>31</b>, <b>32</b>, and <b>33</b>, the base stations <b>41</b>, <b>42</b>, and <b>43</b> calculate distances from the mobile telecommunication terminal based on delayed times for receiving the predetermined signal from the terminal. At this time, in order to calculate the distances more accurately, a height of an antenna mounted at the base station has to be necessarily considered and the Pythagorean theorem is applied.

[0021] The distance calculation algorithm processing units <b>41</b>A, <b>42</b>A, and <b>43</b>A mounted in the base stations <b>41</b>, <b>42</b>, and <b>43</b> include algorithms for calculating distances from the mobile telecommunication terminals and calculate accurate distance values through the algorithms. At this time, the algorithm maybe realized as a program which sequentially calculates distances between the mobile telecommunication terminals and the base stations according to the Pythagorean theorem. The distance calculation for which the Pythagorean theorem is used will be explained.

[0022]FIG. 4 is a diagram explaining a distance calculation between one of the base stations and a mobile telecommunication terminal based on a delayed time of a predetermined signal transmitted from the mobile telecommunication terminal.

[0023] As shown, the distance L between the base station antenna and the mobile telecommunication terminal is obtained by multiplying the height of the antenna h and reach delay time T of the predetermined signals transmitted from the terminal to the base station. Then, the distance D between the terminal and the base station is obtained by using the Pythagorean theorem, where D={square root}{square root over (L²−h²)}.

[0024] Subsequently, the cell controller <b>51</b> combines distance information according to the distance values transmitted from the plurality of base stations and thereby traces locations of the mobile telecommunication terminals. Herein, the cell controller <b>51</b> sets/stores location information corresponding to each distance information in a table (not shown), and identifies the location information according to the distance information through the table, thereby determining regions which are the most similar to locations the mobile telecommunication terminals.

[0025]FIG. 5 is a diagram illustrating a method for tracing a location of the terminal using a table mounted in the cell controller <b>51</b> in accordance with one embodiment of the present invention. This method includes dividing a region around or near one or more base stations into a plurality of areas, calculating distances between each base station and the mobile telecommunication terminal which maybe located in one of the divided areas and setting/storing the distance values and location information by the distance values in the table of the cell controller in advance. The method further includes receiving discrimination information transmitted from the mobile terminal and calculating distances between the mobile terminal and the respective base stations based on a delayed time for receiving the discrimination information.

[0026] The calculated distance values are then transmitted to the cell controller and location information corresponding to the distance values between the mobile telecommunication terminal and the respective base stations transmitted from the respective base stations and discriminated through the table of the cell controller, thereby tracing locations of the mobile telecommunication terminals. A non-limiting example of this method follows.

[0027] In order to trace locations of a mobile telecommunication terminal using three base stations, a region encompassing, near, or adjacent the three base stations is divided into areas A, B, C, . . . and I. It is noted that the divided region is not limited to areas A˜I, as it ts possible to divide the regions into more or fewer areas. Also, even though three base stations are illustrated in drawings, those skilled in the art can appreciate that a different number of base stations maybe included. For example if there are more than three base stations, locations of the terminals located at expanded regions which extend outside the divided areas or which are located at detail areas except the center portion can be traced.

[0028] The respective base stations calculate coordinate values (D1_A, D2_A, D3_A), (D1_B, D2_B, D3_B), (D1_C, D2_C, D3_C) . . . (D1_I, D2_I, D3_I) corresponding to distances between the terminals located at center portions of the divided areas A, B, C, . . . and I and the base stations. Then, the base stations transmit the values to the cell controller which connects the respective base stations. The cell controller previously sets/stores location information corresponding to the coordinate values in the basis table, and discriminates location information corresponding to the coordinate values in the table, to thereby tracing locations of the terminals.

[0029] For example in case that one mobile telecommunication terminal <b>31</b> is located at a center portion of the A region, location tracing may be performed as follows.

[0030] First, the coordinate values corresponding to distances between the base stations <b>41</b>, <b>42</b>, and <b>43</b> and the mobile telecommunication terminal <b>31</b> are calculated at the base stations <b>41</b>, <b>42</b>, and <b>43</b> and transmitted to the cell controller <b>51</b>. Then, the cell controller <b>51</b> discriminates location information previously set and stored in the table mounted therein corresponding to the coordinate values D1, D2, and D3, thereby identifying that terminal <b>31</b> is located at the A region.

[0031] In the case where terminals are located at portions except the center portions in the divided areas, the predetermined region is again divided into detail areas and corresponding coordinate values and location information corresponding to the coordinate values are previously set and stored in the table. Coordinate values corresponding to distances between terminals located at the portions except the center portions in the divided predetermined region and the base stations are calculated in the respective base stations <b>41</b>, <b>42</b>, and <b>43</b>. Subsequently, the cell controller <b>51</b> compares the coordinate values with those stored in the table, determines coordinate values of the basis table corresponding to the coordinate values, and selects location information corresponding to the coordinate values, thereby tracing a location of the mobile telecommunication terminal <b>31</b>.

[0032] The location tracing method for the mobile telecommunication terminal <b>31</b> is suitable for a sophisticated location tracing of the mobile telecommunication terminal, since the divided region is re-divided into detail areas and thereby many coordinate values and location information corresponding to the coordinate values are previously set and stored in the basis table.

[0033] As another example of the location tracing method involves the case where the mobile telecommunication terminal <b>31</b> is located at another portion except a center portion in one or more of the divided areas. Here, the respective divided areas regions are re-divided into several regions not into detail areas, and corresponding coordinate values and location information corresponding to the coordinate values are previously set and stored in the basis table. Then, coordinate values corresponding to distances between the terminal located at another portion except the center portion in the predetermined area and the base stations are calculated in the base stations <b>41</b>, <b>42</b>, and <b>43</b>. Then, the cell controller <b>51</b> compares the coordinate values with those stored in the table, discriminates coordinate values of the basis table which are the most similar to the coordinate values, and selects location information corresponding to the coordinate values, thereby tracing a location of the mobile telecommunication terminal <b>31</b>.

[0034] The case where one mobile telecommunication terminal <b>31</b> is located at another portions except a center portion in the A area will now be explained.

[0035] First, coordinate values corresponding to distances between the base stations <b>41</b>, <b>42</b>, and <b>43</b> and the mobile telecommunication terminal <b>31</b> are calculated at the base stations <b>41</b>, <b>42</b>, and <b>43</b> and transmitted to the cell controller <b>51</b>. The cell controller <b>51</b> compares the coordinate values with those previously calculated and stored in the table in accordance with that the A region is re-divided into several regions, discriminates coordinate values of the basis table which are the most similar to the coordinate values, and selects location information corresponding to the coordinate values, thereby identifying that the mobile telecommunication terminal <b>31</b> is located at the predetermined region of the A region.

[0036] Accordingly, the cell controller <b>51</b> determines and traces locations of the terminals wherever another mobile telecommunication terminals <b>3</b>, . . . <b>39</b> except the terminal <b>31</b> are located among said regions B, C, D . . . , and I.

[0037] Subsequently, the cell controller <b>51</b> transmits region information of the traced mobile telecommunication terminal to the respective mobile telecommunication terminals <b>32</b>, <b>33</b> . . . , and <b>39</b>. Therefore, the respective terminals <b>32</b>, <b>33</b>, . . . and <b>39</b> identify their locations by receiving the region information.

[0038] As aforementioned, in the location tracing system according to the present invention, distances between the terminals and the base stations are calculated by using reach delay time of predetermined signals transmitted from the terminals to the base stations and then the table of the cell controller which previously sets and stores location information corresponding to the calculated distances is identified, thereby tracing locations of the mobile telecommunication terminals. Accordingly, since the location tracing system according to the present invention does not need the GPS receiver which had to be necessarily mounted in the conventional terminal at the time of using the GPS, a system realization is facilitated. Also, since the related resource can be used as it is, a cost is reduced.

[0039] Besides, when compared with the conventional location tracing system for tracing a location of the terminal by using a network of a wireless communication system, the location tracing system according to the present invention has a greatly reduced error range.

[0040] The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.