Handover method and apparatus for mobile terminal using location information in heterogeneous system network

• US 7,720,487 B2
• Filed: 12/05/2005
• Issued: 05/18/2010
• Est. Priority Date: 12/07/2004
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Won Ik, Lee, Bong Ju, Song, Pyeong Jung, Nam, Sang Woo, Song, Jae Su, Shin, Yeon Seung
• Primary Examiner(s): Eng, George
• Assistant Examiner(s): Miller, Brandon J
• Application Number:
  US11/295,126
• Publication Number:
  US 20060121914A1
• Time in Patent Office: 1,625 Days
• Field of Search: 370/328, 370/331, 370/332, 455/456.1, 455/445, 455/448, 455/456.6, 455/456.5, 455/435.1, 455/437, 455/436, 455/440, 455/435.2, 455/435.3, 455/438, 455/439, 455/442, 455/525, 455/67.11, 455/67.13
• US Class Current: 455/456.1
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/322 by location data
• CPC Class Codes: H04W 48/18 Selecting a network or a communication service

Abstract

A handover method and apparatus for a mobile terminal using location information in a network of heterogeneous systems are provided. The handover method uses service area map information provided by a location service server in a mobile communication network in which at least one or more heterogeneous wireless network systems are connected through a predetermined network and, includes: receiving service area map information transmitted from the location service server; the mobile terminal determining whether or not the location of the mobile terminal is within the service area map; and if it is determined that the mobile terminal is within the service area map, the wireless terminal selecting an accessible wireless network system and then activating a unit for communicating with a base station of the selected wireless network system. According to the method, a battery consumption problem that occurs by activating all modems when a wireless terminal, which is connected to a predetermined mobile communication system in an environment where a plurality of heterogeneous systems are overlapping each other, is searching for candidate systems in order to perform handover to a heterogeneous network, can be solved. Also, a problem where finding a candidate system is time-consuming can be solved.

Claims

1. A method of building a service area map of a location service server by using location information of a wireless terminal in a mobile communication network in which at least two heterogeneous wireless network systems are connected to each other through a predetermined network, the method comprising:

forming a network service area map in relation to each of the wireless network systems;

receiving from the wireless terminal a message providing location information of the wireless terminal, intensity values of signals received from base stations of accessible wireless network systems and an identification of the accessible wireless network systems through a wireless network system selected from among the accessible wireless network systems on the basis of the intensities of signals of the accessible wireless network systems;

selecting a reference point closest to the location of the wireless terminal in relation to each of the wireless network systems, based on the location information of the wireless terminal, and storing the intensity value of the signal in a location corresponding to the selected reference point;

detecting whether or not an already stored signal intensity value exists in relation to the selected reference point;

if the detection result indicates that the already stored signal intensity value does not exist, storing the intensity value of the signal in the message providing the location information; and

if the detection result indicates that the already stored signal intensity value exists, obtaining the average value between the already stored signal intensity value and the signal intensity value in the message providing the location information, and storing the average value.

2. The method of claim 1, wherein in the forming of the network service area map, the map is formed by generating a grid shape on a 2-dimensional plane in which the wireless network systems have predetermined intervals respectively in each direction, and selecting the position of each wireless network system as a reference point.

3. The method of claim 2, wherein the network service area map has an interval between the reference points that varies according to the characteristic of each system forming the mobile communication network.

4. The method of claim 1, further comprising:

transmitting the service area map of the wireless network systems set by storing the signal intensity value, to the wireless terminal.

5. The method of claim 1, wherein the message providing the location information further includes an identifier of an accessible wireless network system.

6. A handover method by a wireless terminal in a mobile communication network in which at least one or more heterogeneous wireless network systems are connected through a predetermined network, the method comprising:

detecting accessible wireless network systems and intensities of signals received from base stations of the accessible wireless network systems;

generating a message providing location information, including location information of a wireless terminal obtained based on information provided by a location recognition system, identifications of the detected wireless network systems and the intensity values of signals from the detected wireless network systems;

transmitting the message providing the location information to a location service server located in a common core network through a wireless network system selected on the basis of the intensities of signals of the detected wireless network systems;

receiving service area map information transmitted from the location service server, wherein the service area map information is set based on the message providing the location information;

selecting a wireless network system to move and then activating a unit for communicating with a base station of the selected wireless network system, if the mobile terminal is within the service area map;

the location server establishing the service area map information;

establishing a grid-shape map in which the interval of reference points varies with respect to each wireless network system;

receiving the message providing the location information from the wireless terminal, including the location information of the wireless terminal, an identifier of an accessible wireless network system, and the intensity of a signal received from a base station; and

selecting a reference point closest to the location of the wireless terminal in relation to each of the wireless network systems, based on the location information of the wireless terminal, and storing the intensity of the signal at a location corresponding to the selected reference point;

detecting whether or not an already stored signal intensity value exists in relation to the reference point;

if the detection result indicates that the already stored signal intensity value does not exist, storing the intensity value of the signal included in the message providing the location information at the location corresponding to the selected reference point; and

if the detection result indicates that the already stored signal intensity value exists, obtaining the average value between the already stored signal intensity value and the signal intensity value in the message providing the location information, and updating with the average value the location corresponding to the selected reference point.

7. The method of claim 6, wherein the determining of whether or not the location of the mobile terminal is within the service area map comprises:

the wireless terminal retrieving the current location information of the wireless terminal; and

determining whether or not the location in the location information of the wireless terminal is in the service area map.

8. The method of claim 6, further comprising:

detecting a reception signal received by activating the communication unit for communication with the base station of the selected wireless network system, and determining whether or not the intensity of the detected reception signal is equal to or greater than a preset magnitude.

9. The method of claim 8, further comprising:

if the result of the determination indicates that the intensity of the reception signal is less than the preset magnitude, the wireless terminal inactivating the communication unit for communication with the base station for a predetermined time.

10. The method of claim 8, wherein the preset magnitude is an acceptable threshold of handover of the wireless terminal.

11. A location service server comprising:

a map storage unit generating and storing a grid-shape map in relation to each of wireless network systems forming a mobile communication network;

a reference point selection unit receiving from a wireless terminal a message providing location information, and intensity values of signals received from a base station of accessible wireless network systems and an identification of the accessible wireless network systems through a wireless network system selected from among the accessible wireless network systems on the basis of the intensities of signals of the accessible wireless network systems, searching the map storage unit, and selecting a reference point close to the location of the location information of the wireless terminal

a signal intensity recording unit recording the signal intensity value at the selected reference point of the base station of each of the wireless network systems,

wherein the signal intensity recording unit searches to detect the map storage unit whether or not an already stored signal intensity value exists in relation to the reference point, and if the detection result indicates that the already stored signal intensity value does not exist in relation to the reference point the signal intensity recording unit stores the intensity value of the signal in the message providing the location information, and if the detection result indicates that the already stored signal intensity value exists, the signal intensity recording unit obtains and stores the average value between the already stored signal intensity value and the signal intensity value in the message providing the location information.

12. The location service server of claim 11, further comprising:

an information processing unit transmitting service area map information stored in the map storage unit to the wireless terminal.

13. The location service server of claim 11, wherein the map storage unit forms the map in a grid-shape with predetermined intervals in each direction on a 2-dimensional plane and selects each position as the reference point.