Handover with fast moving mobile station detection between a microcell and a macrocell

• US 5,907,808 A
• Filed: 10/15/1996
• Issued: 05/25/1999
• Est. Priority Date: 04/15/1994
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Halonen, Timo, Vaara, Tomi
• Primary Examiner(s): LE, THANH C
• Application Number:
  US08/727,574
• Time in Patent Office: 952 Days
• Field of Search: 455/422, 455/432, 455/435, 455/436, 455/440, 455/441, 455/443, 455/444, 455/445, 455/455, 455/456, 455/457, 455/458, 455/FOR 100, 455/FOR 101, 455/FOR 103 , 455/FOR 104, 455/FOR 105, 370/329, 370/330, 370/331, 370/332, 370/333, 370/341
• US Class Current: 455/441
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data

Abstract

In a hierarchical micro/macro-cell network, a mobile station will be handed over from a microcell to a macrocell if a number of microcells recognize the mobile station as fast, so that the fast moving mobile stations do not cause a considerable number of handovers between microcells, which make the call control difficult. However, in order to avoid unnecessary switches up to macrocells, a mobile station and the call are handed over to a macrocell only when the mobile station is recognized as fast in a sufficient number of microcells.

Claims

1. A method for implementing handover between a microcell and a macrocell in a cellular mobile system comprising mobile stations, a microcell network used primarily by those of the mobile stations which have a relatively lower transmitting power and speed, and a macrocell network which geographically at least partly overlays the microcell network, the macrocell network being primarily used by those of the mobile stations which have a relatively higher transmitting power and speed, comprising the steps of:

assigning a time limit to at least some of the microcells,

measuring the time between the entry of a mobile station to a microcell and its exit from the microcell,

determining the direction of entry and exit of the mobile station,

recognizing the mobile station as fast in the microcell, if the time measured is shorter than said time limit and the direction of entry is different than the direction of exit, and

handing over a mobile station using a microcell network to a macrocell network, if a sufficient number of microcells recognize the mobile station as fast.

2. The method as claimed in claim 1, further comprising:

assigning at least two groups of neighboring cells to all microcells which have the assigned time limit, each of said groups of neighboring cells including at least one neighboring cell, and

recognizing the mobile station as fast in the microcell, if the time measured is shorter than said time limit, and, if the mobile station has entered the microcell from one group of neighboring cells and exited from the microcell to a second group of neighboring cells.

3. The method as claimed in claim 2, further comprising:

measuring the time between the entry of a mobile station to and its exit from a cell in N consecutive microcells, and handing over of a mobile station using a microcell network to use a macrocell network, if the mobile station is recognized as being fast in P microcells, in which N and P are possible integers, and N≧

P.

4. The method as claimed in claim 1 further comprising:

measuring the time between the entry of a mobile station to and its exit form a cell in N consecutive microcells, and

handing over of a mobile station using a microcell network to use a macrocell network, if the mobile station is recognized as being fast in P microcells, in which N and P are positive integers, and N≧

P.

5. A cellular mobile system comprising:

a plurality of mobile stations some of which have a relatively lower transmitting power and speed, and others of which have a relatively higher transmitting power and speed,

a microcell network primarily used by those of said mobile stations which have a relatively lower transmitting power and speed, said macrocell network comprising a plurality of microcells,

a macrocell network geographically at least partly overlaying said microcell network, and being primarily used by those of said mobile stations which have a relatively higher transmitting power and speed,

at least some of said microcells being assigned at least two groups of neighboring cells each group having at least one neighboring cell,

at least some of said microcells being assigned a predetermined threshold value for the time a respective mobile station is registered to the respective microcell,

said system being arranged such that a respective mobile station primarily using said microcell network can be handed over to said macrocell network, if the respective mobile station moves from one group of neighboring cells relative to one said microcell and, further, to a second group of neighboring cells with such high speed that the time of registration in a microcell is, in a predetermined share of said microcells through which the mobile station moves, shorter than the said predetermined threshold value in each respective microcell.

6. The mobile system according to claim 5, wherein:

each respective said mobile station is arranged to be handed over to said macrocell network, if the time of registration of the respective mobile station in P cells of N consecutive microcells is shorter than said predetermined threshold value, N and P being positive integers, and N≧

P.