Vertical handover method for overlay communication system

• US 8,023,948 B2
• Filed: 09/27/2007
• Issued: 09/20/2011
• Est. Priority Date: 10/10/2006
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Han, Jung Hoon
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US11/862,714
• Publication Number:
  US 20080085712A1
• Time in Patent Office: 1,454 Days
• Field of Search: 455/41.2, 455/41.3, 455436-444, 455450-453, 455/552.1, 455/553.1, 370/328, 370331-334, 370/338
• US Class Current: 455/440
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells

Abstract

A vertical handover method in a heterogeneous overlay network communication system is provided. A vertical handover method for an overlay communication system including a plurality of base stations each serving at least one communication network technology to a mobile terminal includes determining whether a mobile terminal is located in a measurement region with reference to a vertical handover map in relation to a serving base station; detecting reachable base stations by activating all network interfaces when the mobile terminal locates in a measurement region; selecting one of the reachable base stations as a handover target base station; determining if the mobile terminal is located in a handover region with reference to the vertical handover map; and performing a handover if the mobile terminal is located in a handover region.

Claims

1. A vertical handover method for an overlay communication system including a plurality of base stations each providing at least one communication network technology to a mobile terminal, comprising:

determining if a mobile terminal is located in a measurement region with reference to a vertical handover map in relation to a serving base station;

detecting reachable base stations by activating all network interfaces when the mobile terminal is located in a measurement region;

selecting one of the reachable base stations as a handover target base station;

determining if the mobile terminal is located in a handover region with reference to the vertical handover map; and

performing a handover if the mobile terminal is located in a handover region,

wherein the vertical handover map is a map configured by a graph in which an X axis denotes a Distance (D) between the serving base station and the mobile terminal, and a Y axis denotes a traffic Load (L) of the serving base station,

wherein the measurement region is a region determined by the vertical handover map,

wherein the handover region is a region determined by the vertical handover map, and

wherein detecting reachable base stations comprises determining if there is a base station satisfying {└

D_n<

D<sub>n—

MT</sub>┘ and

└

L_n<

L<sub>n—

MT</sub>┘

}, where D_n is a distance between the mobile terminal and n_th base station, L_n is a traffic load of n_th base station, D<sub>n—

MT</sub> is a reachable threshold distance, and L<sub>n—

MT</sub> is a reachable threshold traffic load of the n_th base station.

2. The vertical handover method of claim 1, wherein determining if a mobile terminal is located in a measurement region comprises:

determining if {[D≧

D_advMT] or [L≧

L_advMT]} is satisfied, where D is a distance between the serving base station and the mobile terminal, L is a traffic load of the serving base station, D_advMT is a handover determination distance of the vertical handover map, and L_advMT is a handover determination traffic load of the vertical handover map.

3. The vertical handover method of claim 2, wherein D is calculated by

4. The vertical handover method of claim 2, wherein L is calculated by

5. The vertical handover method of claim 1, wherein detecting reachable base station further comprises registering the reachable base station to a handover candidate base station list.

6. The vertical handover method of claim 1, wherein the handover target base station is selected by min{(D_l+L_l), . . . , (D_m+L_m)}, where D_m is a distance between the mobile terminal and m_th candidate base station, and Lm is a traffic load of m_th candidate base station.