Mobile communication switching across cell boundaries

Patent 5432842 Issued on July 11, 1995. Estimated Expiration Date:

July 11, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3764915

Mobile radio network
Patent #: 4667202
Issued on: 05/19/1987
Inventor: Kammerlander , et al.

Antenna beam boundary detector for preliminary handoff determination
Patent #: 4881082
Issued on: 11/14/1989
Inventor: Graziano

Mobile communication position registering method and system therefor
Patent #: 5095531
Issued on: 03/10/1992
Inventor: Ito

Method of predicting cell-to-cell hand-offs for a satellite cellular communications system
Patent #: 5161248
Issued on: 11/03/1992
Inventor: Bertiger, et al.

Hand-off algorithm for elongated radiotelephone cells
Patent #: 5170485
Issued on: 12/08/1992
Inventor: Levine, et al.

Cellular telephone system that uses position of a mobile unit to make call management decisions
Patent #: 5235633
Issued on: 08/10/1993
Inventor: Dennison, et al.

Method of controlling handoff in cellular mobile radio communications system Patent #: 5239667
Issued on: 08/24/1993
Inventor: Kanai

Inventors

Assignee

Hitachi, Ltd.

Application

No. 852810 filed on 03/17/1992

US Classes:

455/440, Based upon unit location455/441, Based upon unit velocity455/442, Soft handoff455/574Power conservation

Examiners

Primary: Kuntz, Curtis
Assistant: Bost, Dwayne D.

Attorney, Agent or Firm

Fay, Sharpe, Beall, Fagan, Minnich & McKee

Foreign Patent References

0245639 JP. 03/13/1987
0073925 JP 03/13/1989

International Class

H04Q 007/38

Foreign Application Priority Data

1991-03-19 JP

Abstract

With respect to a mobile communication system, intelligence learns a cell boundary where the field strength of adjacent base stations becomes equal, by measuring field strength of communications, and from this data determined and stored over a period of time, the intelligence calculates the position and velocity vector of each mobile unit, from which a priority for hand-off can be determined. Hysteresis of the hand-off is determined with respect to hand-off boundaries located a fixed distance from the measured cell boundary, with hand-off preferably being soft hand-off within the narrow hand-off boundaries. Priority is particularly determined using fuzzy logic and calculation of the time estimated for the mobile unit to reach the cell boundary. Battery consumption of the mobile units is improved by prolonging the interval of checking the position of mobile units, when the mobile units are moving slowly or not moving at all. The determination of the cell boundary is updated continuously, to compensate for environment changes affecting field strength.

Other References

IEEE Communications magazine, "The Cellular Environment of Lightweight Handheld Portables", 1989, pp. 20-29
Fluhr et al, The Bell System Technical Journal, "Control Architecture", vol. 58, No. 1, Jan. 1979, pp. 43-69
Chadha et al, The Bell System Technical Journal, "Mobile Telephone Switching Office", vol. 58, No. 1, Jan. 1979, pp. 71-9