JP2013140123A - Route search device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that path length becomes uselessly long when a route is searched by selecting a radio base station as a detouring spot.SOLUTION: A route search device comprises a route search unit, a route correction unit, and a staying time assignment unit. The route search unit searches for one or more routes that reach an end point from a start point via one or more radio base stations within the limited time. The route correction unit corrects a route by selecting one of the retrieved route which has shorter path length and passes a point that has the same communication quality as the base of a radio base station and exists within a radio coverage area of the radio base station. The staying time assignment unit assigns the difference between the limited time and the time required for moving from the start point to the end point along the corrected route, as the staying time at the point having the best communication quality on the corrected route, to the corrected route.

Description

  The present invention relates to a route search device, and more particularly to a route search device that searches for a route with better communication quality than the shortest route.

  When moving between two points, it is generally desirable to move along the shortest path. However, it is generally not the case for users who want to communicate on the move. For example, consider a case where a user having a mobile terminal such as a mobile phone moves from the start point s to the end point g. At this time, if there is no wireless coverage area on the shortest route, communication cannot be performed even during movement. Therefore, it is not surprising that a mobile terminal user wants to use a route that passes through the wireless coverage area even if the travel time and travel distance increase somewhat.

  In such a situation, Non-Patent Document 1 describes a technique for searching for a route that has better communication quality than the shortest route and can move within the time limit. In the technique described in Non-Patent Document 1, a search area (for example, an urban area) is expressed by a weighted directed graph G = (V, E, C, P). Here, V is a vertex (for example, an intersection), E is a side (for example, a road), C is a moving time function (for example, the time required for moving the side), and P is a communication quality function (for example, a communication speed at each vertex). . Then, given the start point, end point, and time limit, among the routes whose travel time is less than or equal to the time limit, the route with the maximum total transfer amount P (T) given by the following equation is branch-limited. Discover by law.

P (T) = t · P (v _i ) + Σj _{= 1} ^k C (e _j ) · P (e _j ) (1)
Here, C (e _j ) · P (e _j ) is a transfer amount obtained while moving side j, and therefore Σ _{j = 1} ^k C (e _j ) · P (e _j ) Indicates the total transfer amount obtained. P (v _i ) is the communication speed at the peak of the communication speed on the route, and t is the remaining time obtained by subtracting the travel time of the route from the time limit. That is, in Non-Patent Document 1, when the moving time of the route is less than the time limit, the difference t is assigned as the stop time at the vertex having the maximum communication speed on the route. The total transfer amount obtained during this stop time is t · P (v _i ).

  On the other hand, there is a technique described in Patent Document 1 as another technique related to the present invention. In the technique described in Patent Document 1, when there is a time margin in the route search from the start point to the end point, an appropriate detour spot (such as a restaurant or a museum) is selected, and the route including the detour spot is given to the user. Present. In addition, the next stop spot narrows down the search target area by searching from the area where the user can stop from the spot where the user exists and reach the end point in the remaining time. Specifically, the total distance that can be moved within the remaining time can be calculated from the remaining time and the average moving speed, and the average movement can be obtained by detouring within the total distance from the point where the user exists and reaching the end point. When the speed is assumed to be constant, the search target area is elliptical.

JP 2003-139553 A

The Institute of Electronics, Information and Communication Engineers, IEICE Technical Report, IEICE Technical Report RCS2009-269 (2010-03), p71-76, Yuichi Shudo et al., “Characteristics of Optimal“ Detour ”Path for Wireless Mobile Users”

  However, since the technique described in Non-Patent Document 1 is an algorithm that performs all-route search, the calculation amount is basically increased, and there is a waste of searching outside an elliptical region that cannot move within the time limit. On the other hand, the technique described in Patent Document 1 is not limited to searching for all routes, but because the search range is narrowed down to an elliptical area that can move within the time limit, route search can be performed with a small amount of calculation and without waste. is there. However, when a route with good communication quality is searched using the technique of Patent Document 1, there is a problem that the route length becomes unnecessarily long. Hereinafter, this problem will be described.

  When searching for a route with good communication quality using the technique described in Patent Document 1, the wireless base station corresponds to a detour spot. For this reason, when the start point s, the end point g, and the radio base station BS are in a positional relationship as shown in FIG. 9, for example, in the technique described in Patent Document 1, the end point g is passed from the start point s via the radio base station BS. A route L1 leading to is searched.

  In general, in the radio coverage area of the radio base station BS, the closer to the radio base station BS, the stronger the radio strength and the better the communication quality. However, when there is an upper limit on the maximum transfer amount, the transfer amount does not increase beyond that even if the radio base station is approached from a certain distance. That is, the place where the maximum communication quality is obtained is not a point on the Euclidean plane but a plane on the Euclidean plane. Assume that the same communication quality as that immediately below the radio base station BS is obtained in the circle area indicated by the reference symbol RZ in FIG. Further, the points where the detour route L1 crosses the area RZ are p1 and p2, and the route L2 from the start point s to the end point g via p1 and p2 is considered. As is clear from the triangular inequality on the Euclidean plane, the distance from p1 directly to p2 is shorter than p1 from p1 in FIG. 9 via the radio base station BS. Is also shortened. Assuming that the time that can be shortened is Δt, the total obtained when starting from the start point s and stopping at an arbitrary position between p1 and p2 on the path L2 and then moving to the end point g along the path L2. The transfer amount is equal to the total transfer amount obtained when moving along the path L1. That is, the route L2 has a shorter route length while the total transfer amount is the same as that of the route L1. If there are a plurality of routes having the same communication quality, it is considered that there are many users who prefer a shorter route length.

  An object of the present invention is to solve the above-described problem, that is, the problem that a path length becomes uselessly long when a route is searched by selecting a radio base station as a detour spot.

A route search apparatus according to an aspect of the present invention is provided.
A route search unit for searching for one or more routes from the start point via one or more wireless base stations to the end point within the time limit;
A path correction unit that corrects the searched path to a path with a shorter path length that has a communication quality equivalent to that directly under the radio base station and passes through a point existing in the radio coverage area of the radio base station; ,
The difference between the time required to move from the start point to the end point along the corrected route and the time limit is the stay time at the point where the communication quality on the corrected route is maximum. And a staying time granting part to be given to the route.

  Since the present invention has the above-described configuration, it is possible to obtain a route that has a shorter route length than a route searched by selecting a radio base station as a detour spot and does not deteriorate the total communication quality.

It is a block diagram of the route search device concerning a 1st embodiment of the present invention. It is a flowchart which shows operation | movement of the route search apparatus concerning the 1st Embodiment of this invention. It is operation | movement explanatory drawing of the route search part in the route search apparatus concerning the 1st Embodiment of this invention. It is a figure which shows the process of searching the path | route which reaches | attains within a time limit via two radio base stations from a start point to an end point. It is a figure explaining the operation | movement which correct | amends to a path | route with a shorter path | route length by taking the path | route which reaches | attains via one wireless base station from a starting point to an end point as an example. It is a figure explaining another operation | movement which correct | amends to a path | route with shorter path | route length by taking the path | route which reaches | attains via one wireless base station from a starting point to an end point as an example. It is a block diagram of the path | route search apparatus concerning the 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the route search apparatus concerning the 2nd Embodiment of this invention. It is explanatory drawing of the subject which this invention tends to solve.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
[First embodiment]
Referring to FIG. 1, a route search apparatus 10 according to the first embodiment of the present invention includes, as hardware, a communication interface unit (hereinafter referred to as a communication I / F unit) 11, an operation input unit 12, and a screen display unit 13. A storage unit 14 and a processor 15.

  The communication I / F unit 11 includes a dedicated data communication circuit and has a function of performing data communication with various devices connected via a communication line (not shown). The operation input unit 12 includes an operation input device such as a keyboard and a mouse, and has a function of detecting an operator operation and outputting the operation to the processor 15. The screen display unit 13 includes a screen display device such as an LCD or a PDP, and has a function of displaying various information such as operation menus and search results on the screen in accordance with instructions from the processor 15.

  The storage unit 14 includes a storage device such as a hard disk or a memory, and has a function of storing processing information and programs 14P necessary for various processes in the processor 15. The program 14P is a program that realizes various processing units by being read and executed by the processor 15, and an external device (not shown) or a storage medium via a data input / output function such as the communication I / F unit 11 (Not shown) is read in advance and stored in the storage unit 14. Main processing information stored in the storage unit 14 includes start point information 14A, end point information 14B, time limit 14C, movement speed 14D, number of routes 14E, number of via stations 14F, map information 14G, radio coverage information 14H, and search results. There is 14I.

  The starting point information 14A is information for specifying a point that is a starting point, for example, a coordinate value of the starting point. The end point information 14B is information for specifying a destination, for example, a coordinate value of the destination. The time limit 14C is an upper limit value of the time allowed for movement from the departure place to the destination. The moving speed 14D is an average value of the moving speed from the departure place to the destination. The route number 14E is the upper limit number of routes to be searched. The number of via stations 14F is the number of radio base stations that pass through.

  The map information 14G is geographical information of a region where a route is searched. The map information 14G may be expressed by a weighted directed graph G = (V, E, C, P) as described in Non-Patent Document 1. The map information 14G may be a map database used in a car navigation system.

  The wireless coverage information 14H is information on the position of the wireless base station and information on the wireless coverage area. The information regarding the position of the radio base station is, for example, a coordinate value of the radio base station. The information on the radio coverage area includes information on communication quality (for example, maximum transfer amount) directly under the radio base station and geographical information on an area where communication quality equivalent to the information is obtained. The geographical information of the area may be approximated by the radius of a circle centered on the radio base station, or may be coordinate information that defines the area in more detail.

  The search result 14I is information on a route obtained by the route search device 10. The route information includes geographical information of a route from the start point to the end point. Further, when stopping on the route, it has geographical information on the point to stop and information on the stop time.

  The processor 15 has a microprocessor such as an MPU and its peripheral circuits, and reads and executes the program 14P from the storage unit 14 to thereby realize various processing units by cooperating the hardware and the program 14P. have. As main processing units realized by the processor 15, there are an input unit 15A, a route search unit 15B, a route correction unit 15C, a stay time granting unit 15D, and an output unit 15E.

  The input unit 15A receives a search request from the communication I / F unit 11 or the operation input unit 12, and includes start point information 14A, end point information 14B, time limit 14C, movement speed 14D, number of routes 14E included in the search request, and It has a function of storing the number of via stations 14F in the storage unit 14.

  The route search unit 15B reads the start point information 14A, the end point information 14B, the time limit 14C, the moving speed 14D, the number of routes 14E, the number of route stations 14F, the map information 14G, and the radio coverage information 14H from the storage unit 14, and starts the point information 14A. The number of routes that reach within the time limit given by the time limit 14C from the start point given in step S1 through the number of wireless base stations given by the number of via stations 14F to the end point given by the end point information 14B It has a function of searching from the map information 14G with the number given by 14E as the upper limit.

  The route correction unit 15C inputs the route information searched from the route search unit 15B, reads necessary information such as the map information 14G from the storage unit 14, and passes through the route searched by the route search unit 15B. The wireless base station has a function of correcting a route with a shorter route length via a point other than the wireless base station that can obtain the same communication quality as that directly under the wireless base station within the wireless coverage area of the wireless base station.

  The stay time granting unit 15D inputs the corrected route information from the route correcting unit 15C, reads necessary information such as the moving speed 14D and the map information 14G from the storage unit 14, and is corrected by the route correcting unit 15C. It has a function of calculating the difference between the time required for moving from the start point to the end point along the route and the time limit as the remaining time. The stay time granting unit 15D has a function of giving the calculated remaining time to the corrected route as a stay time at a point where the communication quality on the corrected route is maximum. The stay time granting unit 15D has a function of storing, in the storage unit 14, the corrected route that has been given the stay time as a search result 14I.

  The output unit 15E has a function of reading the search result 14I from the storage unit 14 and outputting it to the outside through the communication I / F unit 11 or displaying it on the screen display unit 13.

  Next, the operation of this embodiment will be described.

  First, the input unit 15A inputs a search request from the communication I / F unit 11 or the operation input unit 12, and starts point information 14A, end point information 14B, time limit 14C, movement speed 14D, number of routes 14E included in the search request, Then, the number of relay stations 14F is stored in the storage unit 14 (step S1 in FIG. 2).

  Next, the route searching unit 15B gives the time limit 14C from the start point given by the start point information 14A to the end point given by the end point information 14B via the number of wireless base stations given by the number of via stations 14F. The route reaching within the time limit is searched from the map information 14G with the number given by the route number 14E as the upper limit (step S2).

  Next, the route correction unit 15C passes the searched route through a point other than the wireless base station that can obtain communication quality equivalent to that directly under the wireless base station in the wireless coverage area of the wireless base station that passes through the route. The route is corrected to a short route (step S3).

  Next, the stay time granting unit 15D determines the difference between the time required to move from the start point to the end point along the corrected route and the time limit, and stays at the point where the communication quality on the corrected route is the maximum. The time is given to the corrected route and stored in the storage unit 14 as the search result 14I (step S4).

  Finally, the output unit 15E reads the search result 14I from the storage unit 14 and outputs it to the outside through the communication I / F unit 11 or displays it on the screen display unit 13 (step S5).

  Next, the detailed operation of the route search unit 15B will be described with reference to FIG. FIG. 3 is an explanatory diagram of the route search operation of the route search unit 15B.

(Number of via stations 14F = 1)
When the number of via stations 14F is 1, the route search unit 15B sets the ellipse D1 of FIG. 3 on the map as a search space, and sets the number of routes 14E as the upper limit from the area within the ellipse D1. Select a station. Here, the ellipse D1 is an ellipse having the start point s and the end point g as the focal point, and the sum of the distances from the points on the circumference to the start point s and the end point g is equal to the total distance that can move during the time limit 14C. The total distance can be obtained by multiplying the moving speed 14D by the time limit 14C.

  When the number of wireless base stations BS1 to BSn1 exceeding the number of paths 14E exists in the ellipse D1, the route search unit 15B preferentially selects a wireless base station having a shorter sum of distances from the start point s and the end point g. . Alternatively, the route search unit 15B may select a radio base station according to other criteria, such as preferentially selecting a radio base station with better communication quality.

  The path search unit 15B searches the map for the shortest path from the start point s to the radio base station and the shortest path from the radio base station to the end point g for each selected radio base station. Generate a route that connects routes together.

(Number of via stations 14F ≧ 2)
When the number of via stations 14F is 2 or more, the route search unit 15B first sets the ellipse D1 in FIG. 3 on the map, and considers the radio base stations that pass through the second and subsequent regions from the area within the ellipse D1, A candidate for a wireless base station to be first routed is selected. Specifically, the radio base station and the end point g that pass through first are focused, and the sum of the distance from the point on the circumference to the radio base station and the end point g that passes first is within the remaining time given by the following equation: A radio base station is selected as a candidate only if there are more radio base stations than the number of remaining via stations in the elliptical area equal to the total distance that can be moved. .
Remaining time = restricted time−movement time of the shortest path from the start point s to the radio base station (2)

  FIG. 4 shows a process of searching for a route that reaches within the time limit from the start point s to the end point g via two radio base stations. In FIG. 4, when the radio base station BS1 is selected as the first transit station, the radio base station BS1 and the end point g are the focal points, and the sum of the distances from the points on the circumference to the radio base station BS1 and the end point g is the above ( 2) If an ellipse equal to the total distance that can be moved within the remaining time given by equation (2) is D21, in addition to the radio base station BS1, one or more radio base stations BS2 that are the number of remaining via stations are included in the area of this ellipse D21. Since it exists, the radio base station BS1 becomes a selection candidate. On the other hand, when the radio base station BS3 is selected as the first transit station, the sum of the distances from the points on the circumference to the radio base station BS3 and the end point g is expressed by the above equation (2). If the ellipse that is equal to the total distance that can be moved within the remaining time given by D23 is D23, there is no one or more radio base stations that are the number of remaining via stations other than the radio base station BS3 in the area of this ellipse D23. The radio base station BS3 is excluded from the selection candidates.

The route search unit 15B selects a wireless base station that is first routed from the selection candidates obtained as described above. When there are a plurality of selection candidates, the route search unit 15B preferentially selects a radio base station having a higher throughput density of the ellipse (D21 or the like). Here, the throughput density of the ellipse is given by the following equation.
Throughput density = (Σ _{i = 1} ⁿ transfer rate i × radio coverage area area i) / elliptical area (3)
Here, i indicates the i-th radio coverage area included in the ellipse.

  For example, in the case of the ellipse D21 in FIG. 4, a value obtained by multiplying the transfer rate of the radio coverage area RZ1 by the area of the radio coverage area RZ1 included in the ellipse D21 and the transfer rate of the radio coverage area RZ2 included in the ellipse D21. A value obtained by dividing the sum of the value multiplied by the area of RZ2 and the area of the ellipse D21 is the throughput density of the ellipse D21.

  Next, the route search unit 15B selects the second radio base station that passes after the first transit station selected as described above from the area within the ellipse D1. Here, a method of selecting the second radio base station will be described assuming that the radio base station BS1 is selected as the first transit station.

  The route search unit 15B focuses on the ellipse D21, that is, the radio base station BS1 and the end point g, and the sum of the distances from the points on the circumference to the radio base station BS1 and the end point g is given by the above equation (2). An ellipse that is equal to the total distance that can be moved in time is set on the map, and the second wireless base station that passes through the area within the ellipse D21 is selected.

  When the second radio base station is the last transit station, that is, when the number of transit stations 14F is 2, the route search unit 15B sums the distances from the area within the ellipse D21 from the radio base station BS1 and the end point g. Are preferentially selected so as not to exceed the number of paths 14E. Alternatively, the route search unit 15B may select a radio base station according to other criteria, such as preferentially selecting a radio base station with better communication quality. By such an operation, for example, if the path number 14E is 2, two radio base stations BS11 and BS12 are selected from the ellipse D21 in FIG. If the number of radio base stations existing in the ellipse D21 is less than the path number 14E, all the radio base stations existing in the ellipse D21 are selected. Then, for each radio base station selected as the second route, the route search unit 15B connects the shortest route from the start point s to the radio base station BS1 and the second radio base station from the radio base station BS1. And the shortest route from the second wireless base station to the end point g is searched on the map, and a route in which these shortest routes are connected is generated.

  When the second route station is not the last route station, that is, when the number of route stations 14F is 3 or more, the route search unit 15B uses the same method as the method for selecting the first wireless base station, Select a base station. Thereafter, the selection is made in the same manner up to the radio base station immediately preceding the radio base station through which it finally passes. Then, when the last wireless base station to be routed is selected, the last number of wireless base stations to be routed by the number not exceeding the number of paths 14E is obtained in the same manner as in the case of selecting the last routed station. select. For example, if the number of via stations 14F is 3 and the number of paths 14E is 2, two radio base stations BS111 and BS112 are selected from the ellipse D31 in FIG. If the number of radio base stations existing in the ellipse D31 is less than the path number 14E, all radio base stations existing in the ellipse D31 are selected. Then, for each radio base station selected as the last route to be routed, the route search unit 15B obtains the shortest route from the start point s to the radio base station BS1 and the second radio base station from the radio base station BS1. The shortest distance,..., The shortest route from the last wireless base station to the end point g are searched on the map, and a route in which these shortest routes are connected in order of generation is generated.

  The above method is an example, and the route reaching the end point from the start point through the number of wireless base stations given by the number of via stations 14F to the end point is limited to the number given by the number of routes 14E. The searching method is not limited to the above-described method. For example, when the number of via stations 14F is 2 or more and the number of radio base stations to be routed last is less than the number 14E of routes, the process returns to the selection of a via station on the side close to the start point s and a new via station The route satisfying the number of routes 14E may be searched by selecting and selecting a relay station thereunder. For example, when the number of via stations 14F is 2, if the number of paths is insufficient only by using the radio base station BS1 of FIG. 3 as the first via station, the radio base station BS2 having the next highest priority from the ellipse D1 Newly selected as a via station, focusing on the radio base station BS2 and the end point g, and the sum of the distances from the points on the circumference to the radio base station BS2 and the end point g within the remaining time given by the above equation (2) An ellipse that is equal to the total distance that can be moved to is set on the map, and the second wireless base station that passes through the area within this ellipse may be selected.

  Next, the operation of the route correction unit 15C will be described in detail.

  The route correction unit 15C first obtains a point where the route obtained by the route search unit 15B intersects the outer periphery of the wireless coverage area of the wireless base station. When the wireless coverage area is circular and does not include the start point and the end point, there are two points where the routes intersect per one wireless coverage area. Next, the route correction unit 15C searches for the shortest route between two intersections that intersect the route for each wireless coverage area for which two intersections are obtained. Next, the route correction unit 15C replaces the route between the intersections passing through the wireless base station among the routes obtained by the route search unit 15B for each wireless coverage area with the shortest route between the intersections. The path generated in this way is set as a corrected path.

  FIG. 5 shows how the path L11 that reaches from the start point s to the end point g via one radio base station BS1 is corrected. A route L11 connecting the shortest route from the start point s to the radio base station BS1 and the shortest route from the radio base station BS1 to the end point g is a route searched by the route search unit 15B. The route correction unit 15C calculates points p11 and p12 where the route L11 intersects with the radio coverage area RZ1 of the radio base station BS1. Next, the route correction unit 15C searches for the shortest route from the point p11 to the point p12. Finally, the route correction unit 15C replaces the route L12 in which the route portion from the point p11 to the point p12 via the wireless base station BS1 in the original route L11 is replaced with the shortest route from the point p11 to the point p12. And calculated as a correction route. In the example of FIG. 5, the path L11 passes only through the radio base station BS1, but when the route L11 passes through another radio base station, the radio base station BS1 is also connected to the radio coverage area of the other radio base station. Perform the same correction work as the wireless coverage area.

  The correction method by the route correction unit 15C is not limited to the method described above, and other methods may be used. For example, the route correction unit 15C determines the route searched by the route search unit 15B from the start point s via the midpoint of the shortest route between the place that enters the wireless coverage area and the place that leaves the wireless coverage area. You may make it replace with the shortest path | route which reaches the end point g. FIG. 6 shows how the correction route is obtained by this method. The midpoint of the shortest route between the intersection point p11 and the intersection point p12 is calculated, the shortest route from the start point s to the midpoint, and the midpoint to the end point g. The shortest route up to is obtained, and the route connecting them is defined as a corrected route L21.

  When the wireless coverage area is circular and includes one of the start point and the end point, there is only one intersection where the route intersects the outer periphery of the wireless coverage area. In such a case, the route correction unit 15C may obtain the shortest route between the one intersection and the start point or the end point as the correction route. Further, when the wireless coverage area includes both the start point and the end point, there is no intersection where the route intersects the outer periphery of the wireless coverage area. In such a case, the route correction unit 15C may obtain the shortest route from the start point to the end point as the correction route.

  Next, the detailed operation of the stay time granting unit 15D will be described.

  First, the stay time granting unit 15D calculates the time required to move from the start point s to the end point g along the correction route calculated by the route correction unit 15C. The movement time can be obtained by dividing the path length of the correction path by the movement speed. Next, the stay time granting unit 15D calculates the remaining time by subtracting the travel time from the time limit. Next, the staying time giving unit 15D finds a point having the maximum communication quality on the corrected route, and gives the calculated remaining time as the staying time (stopping time) at the found point. For example, in the case of FIG. 5, since the communication qualities are all equal in the radio coverage area RZ1, any point on the route from the point p11 to the point p12 can be set as the staying point. The stay time granting unit 15D stores the contents of the stay point information and the stay time given to the corrected route in the storage unit 14 as the search result 14I.

  As described above, according to the present embodiment, after searching for a route passing through the wireless base station, communication quality equivalent to that directly under the wireless base station can be obtained within the wireless coverage area of the wireless base station passing through the route. The route is corrected to a route with a shorter route length, and the difference between the travel time and the time limit of the corrected route is given as the stay time at the point where the communication quality on the corrected route is the maximum. As a result, it is possible to obtain a route that has a shorter route length than the route that passes through the radio base station and that does not deteriorate the total communication quality.

[Second Embodiment]
Referring to FIG. 7, the route search apparatus 20 according to the second embodiment of the present invention is the same as the first embodiment of the present invention shown in FIG. 1 in that the processor 15 further includes an optimum route selection unit 15F. This is different from the route search apparatus 10. The optimum route selection unit 15F is realized by the program 14P as in the route search unit 15B.

  The optimum route selection unit 15F reads the search result 14I stored in the storage unit 14 by the stay time granting unit 15D, that is, the information of the corrected route to which the stay time is given, and the total communication quality amount for each route after the correction. And the corrected route with the maximum total communication quality amount is stored in the search result 14I as the optimum route. The total communication quality amount of the corrected route is given by the following equation.

Total communication quality = Transfer rate at the point where communication quality is the maximum x Stay time + Total transfer amount obtained while moving (4)

  Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

  First, the input unit 15A inputs a search request from the communication I / F unit 11 or the operation input unit 12, and starts point information 14A, end point information 14B, time limit 14C, movement speed 14D, number of routes 14E included in the search request, And the number 14F of via stations is stored in the storage unit 14 (step S11 in FIG. 8). Since it is important to evaluate a large number of routes in order to search for a more optimal route, it is desirable that the number of routes 14E is designated as infinity or no upper limit. Further, the number of via stations 14F is the number of all possible via stations, that is, 1, 2,..., M (m is a preset maximum via station) so that all routes having different numbers of via stations can be evaluated. It is desirable to specify a number.

  Next, the route searching unit 15B gives the time limit 14C from the start point given by the start point information 14A to the end point given by the end point information 14B via the number of wireless base stations given by the number of via stations 14F. The route reaching within the time limit is searched from the map information 14G with the number given by the route number 14E as the upper limit (step S12). When 1, 2,..., M are specified as the number of via stations 14F, the route search unit 15B performs the operation of the number of route stations = 1, the operation of the number of route stations = 2 described in the first embodiment, ..., the number of path stations = m is operated.

  Next, the route correction unit 15C passes the searched route through a point other than the wireless base station that can obtain communication quality equivalent to that directly under the wireless base station in the wireless coverage area of the wireless base station that passes through the route. The route is corrected to a short route (step S13).

  Next, the stay time granting unit 15D determines the difference between the time required to move from the start point to the end point along the corrected route and the time limit, and stays at the point where the communication quality on the corrected route is the maximum. The time is given to the corrected route and stored in the storage unit 14 as the search result 14I (step S14).

  Next, the optimal route selection unit 15F calculates the total communication quality amount for each corrected route given the stay time, and stores the corrected route with the maximum total communication quality amount as the optimal route in the search result 14I. (Step S15).

  Finally, the output unit 15E reads the information on the optimum route in the search result 14I from the storage unit 14 and outputs the information to the outside through the communication I / F unit 11 or displays it on the screen display unit 13 (step S16).

  As described above, according to the present embodiment, after searching for a route passing through the wireless base station, communication quality equivalent to that directly under the wireless base station can be obtained within the wireless coverage area of the wireless base station passing through the route. The route is corrected to a route with a shorter route length, and the difference between the travel time and the time limit of the corrected route is given as the stay time at the point where the communication quality on the corrected route is the maximum. As a result, it is possible to obtain a route that has a shorter route length than the route that passes through the radio base station and that does not deteriorate the total communication quality.

  Further, according to the present embodiment, a corrected route having the maximum total communication quality amount can be selected as the optimum route from the obtained routes.

  Although the present invention has been described with reference to some embodiments, the present invention is not limited to the above embodiments, and various other additions and modifications can be made.

  For example, although the transfer amount is used as communication quality, a transmission error rate, QOS (Quality Of Service), transmission delay time, total communication time, and the like may be used as communication quality.

  The moving speed 14D, the number of routes 14E, and the number of transit stations 14F are assumed to be given by the user through a search request, but may be specified by the user separately from the search request or may be parameters fixed to the system. There may be.

  In addition, the information of the radio coverage area includes not only the geographical information of the area where the communication quality equivalent to that directly under the radio base station can be obtained, but also the geographical information of the area where the communication quality is inferior to that. Good. In addition, it is not always necessary to pass through an area where communication quality equivalent to that directly under the radio base station can be obtained in all the radio base stations that pass through, and the communication quality is lower because it is necessary to shorten the path length due to the time limit. There may be a radio base station passing through the area.

  Further, the route search device may be mounted on a mobile terminal such as a mobile phone, or may be mounted on a server device that receives and processes a search request from the mobile terminal via a network. At that time, the route search unit 15B, the route correction unit 15C, the stay time granting unit 15D, and the like do not necessarily need to physically exist on the same computer, and may be distributed in a plurality of computers.

DESCRIPTION OF SYMBOLS 10 ... Path | route search apparatus 11 ... Communication I / F part 12 ... Operation input part 13 ... Screen display part 14 ... Memory | storage part 15 ... Processor

Claims (9)

A route search unit for searching for one or more routes from the start point via one or more wireless base stations to the end point within the time limit;
A path correcting unit that corrects the searched path to a path with a shorter path length that has a communication quality equivalent to that directly under the radio base station and passes through a point existing in the radio coverage area of the radio base station; ,
The difference between the time required to move from the start point to the end point along the corrected route and the time limit is defined as the stay time at the point where the communication quality on the corrected route is maximum. A route search device having a stay time granting unit for giving to the route. The route correction unit replaces a route portion passing through the wireless coverage area in the searched route with a shortest route between a portion entering the wireless coverage area and a portion leaving the wireless coverage area. The route search device according to claim 1. The route correction unit reaches the end point from the start point through the midpoint of the shortest route between the place entering the radio coverage area and the place leaving the radio coverage area. The route search device according to claim 1, wherein the route search device is replaced with a shortest route. The route search unit starts from the start point or the radio base station that passes immediately before, has the start point and the end point as a focus, and the sum of the distance from a point on the circumference to the start point and the end point is calculated from the start point. A first ellipse that is equal to the total distance that can be moved within the remaining time allowed to move to the end point is set on the search plane, and the radio base station that passes next is selected from the area within the first ellipse The route search device according to any one of claims 1 to 3. The route search unit is the radio base station existing in the first ellipse when the radio base station selected from the area in the first ellipse is other than the radio base station through which the route last passes. The sum of the distances from a point on the circumference to the radio base station and the end point is within the remaining time allowed for movement from the radio base station to the end point. In the second elliptical area equal to the total distance that can be moved, the radio base station in which more than the number of radio base stations that pass through after the radio base station is excluded is selected as the selection candidate. The route search device according to claim 4, wherein the radio base station to be routed next is selected from among the routes. The route search unit, when there are a plurality of selection candidates, the communication quality amount calculated for each radio coverage area of the radio base station existing in the second ellipse, which occupies the area of the second ellipse, The route search device according to claim 5, wherein the route selection apparatus preferentially selects the selection candidate having a larger ratio of a value obtained by accumulating a multiplication value with a radio coverage area included in the second ellipse. 7. The optimal route selection unit according to any one of claims 1 to 6, further comprising an optimal route selection unit that calculates a total communication quality amount for each of the modified routes to which the stay time is given and selects a route having the maximum total communication quality amount as an optimal route. The route search device according to claim 1. A route search method executed by a route search device having a route search unit, a route correction unit, and a stay time grant unit,
The route search unit searches for one or more routes that reach the end point from the start point via one or more radio base stations to the end point,
The route correction unit converts the searched route to a route with a shorter route length that has a communication quality equivalent to that directly under the wireless base station and passes through a point existing in the wireless coverage area of the wireless base station. correct,
The difference between the time required for the stay time granting unit to move from the start point to the end point along the corrected route and the time limit at the point where the communication quality on the corrected route is the maximum. A route search method for assigning to the corrected route as the staying time. Computer
A route search unit for searching for one or more routes from the start point via one or more wireless base stations to the end point within the time limit;
A path correcting unit that corrects the searched path to a path with a shorter path length that has a communication quality equivalent to that directly under the radio base station and passes through a point existing in the radio coverage area of the radio base station; ,
The difference between the time required to move from the start point to the end point along the corrected route and the time limit is defined as the stay time at the point where the communication quality on the corrected route is maximum. A program for functioning as a staying time granting part to be given to the route.

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