CDMA type mobile communication system capable of realizing soft handoff between cells having different cell diameters

• US 6,119,018 A
• Filed: 06/06/1997
• Issued: 09/12/2000
• Est. Priority Date: 06/07/1996
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kondo, Seiji
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Armstrong, Darnell R.
• Application Number:
  US08/870,619
• Time in Patent Office: 1,194 Days
• Field of Search: 455/522, 455/422, 455/432, 455/436, 455/442, 455/574, 455/38.3, 455/439, 455/343, 370/332, 370/320, 370/342, 370/335
• US Class Current: 455/522
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Each radio base station (12-1, 12-2) receives an upward communication channel signal from a mobile station (13-2), calculates a transmission power control signal on the basis of the upward communication channel signal, and transmits the transmission power control signal. A host station (11A) receives the transmission power control signals from the radio base stations as received transmission power control signals, selects, as a selected transmission power control signal, one of the received transmission power control signals that makes upward transmission power for the mobile station the lowest power level, and transmits the selected transmission power control signal to a particular one of the radio base stations that communicates with the mobile station. The particular radio base station receives the selected transmission power control signal and transmits the selected transmission power control signal. The mobile station receives the selected transmission power control signal and controls the upward transmission power on the basis of the selected transmission power control signal.

Claims

1. In a mobile communication system comprising a plurality of radio base stations covering respective service areas, at least one mobile station moving in the service areas to carry out radio communication between the mobile station and the radio base stations, and a host station connected to said radio base stations,

each of said radio base stations comprising:

a receiver for receiving an upward communication channel signal from said mobile station;

a processor for calculating, on the basis of the upward communication channel signal, a transmission power control signal for controlling transmission power for said mobile station; and

a transmitter for transmitting the transmission power control signal to said host station,

said host station comprising;

a receiver for receiving the transmission power control signals from said radio base stations as received transmission power control signals;

a selection device for selecting, as a selected transmission power control signal, one of the received transmission power control signals that provides the lowest transmission power for said mobile station of any of the received transmission power control signals; and

a transmitter for transmitting the selected transmission power control signal to a particular one of the radio base stations that communicates with said mobile station,

each of said radio base stations further comprising;

a receiver for receiving the selected transmission power control signal from said host station; and

a transmitter for transmitting the selected transmission power control signal to said mobile station,

said mobile station comprising;

a receiver for receiving the selected transmission power control signal from the radio base station communicating with said mobile station; and

a controller for controlling the transmission power on the basis of the selected transmission power control signal.

2. In a mobile communication system comprising a plurality of radio base stations covering respective service areas and at least one mobile station moving in the service areas to carry out radio communication between the mobile station and the radio base stations, and a host station connected to said radio base stations,

each of said radio base stations comprising:

a receiver for receiving an upward communication channel signal from said mobile station;

a processor for calculating, on the basis of the upward communication channel signal, a transmission power control signal for controlling transmission power for said mobile station;

a transmitter for transmitting the transmission power control signal to said host station;

a receiver in said host station for receiving the transmission power control signals from said radio base stations as received transmission power control signals;

a selector in said host station for selecting, as a selected transmission power control signal, one of the received transmission power control signals that provides the lowest transmission power for said mobile station of any of the received transmission power control signals; and

a transmitter in said host station for transmitting the selected transmission power control signal to said mobile station via a base station corresponding to the selected transmission power control signal,

wherein the radio base stations are connected via a private line, and transmission and reception of said power control signal occurs via said private line,

said mobile station comprising;

a receiver for receiving the selected transmission power control signal from the radio base station communicating therewith; and

a controller for controlling the transmission power therefor on the basis of the selected transmission power control signal.

3. A method of controlling transmission power for a mobile station for use in a mobile communication system comprising a plurality of radio base stations covering respective service areas and a host station connected to said radio base stations, said mobile station moving in the service areas to carry out radio communication between the mobile station and the radio base stations, said method comprising the steps of:

receiving, in a number of said radio base stations, an upward communication channel signal from said mobile station;

calculating, in said number of radio base stations, a transmission power control signal for controlling the transmission power of said mobile station on the basis of the upward communication channel signal;

transmitting the transmission power control signal from said number of radio base stations to said host station,

receiving, in said host station, the transmission power control signals from said number of radio base stations as received transmission power control signals;

selecting, in said host station, as a selected transmission power control signal, one of the received transmission power control signals that provides the lowest transmission power for said mobile station among the received power control signals;

transmitting, from said host station, the selected transmission power control signal to a particular one of said radio base stations that communicates with the mobile station;

receiving, in the particular one of said radio base stations, the selected transmission power control signal from said host station;

transmitting, from the particular one of said radio base stations, the selected transmission power control signal to said mobile station,

receiving, in said mobile station, the selected transmission power control signal from the particular one of said radio base stations; and

controlling, in said mobile station, the transmission power on the basis of the selected transmission power control signal.

4. A method of controlling transmission power for a mobile station for use in a mobile communication system comprising a plurality of radio base stations covering respective service areas and connected by a private line, said mobile station moving in the service areas to carry out radio communication between said mobile station and said radio base stations, said method comprising the steps of:

receiving, in a number of said radio base stations, an upward communication channel signal from said mobile station;

calculating, in said number of radio base stations, a transmission power control signal for controlling the transmission power for said mobile station on the basis of the upward communication channel signal;

transmitting the transmission power control signal from said number of radio base stations to said host station;

receiving, in said host station, the transmission power control signals from said number of radio base stations as received transmission power control signals;

selecting, in said host station, as a selected transmission power control signal, one of the received transmission power control signals that provides the lowest transmission power for said mobile station among the received power control signals;

transmitting the selected transmission power control signal from said host station via said radio base stations to said mobile station,

receiving, in said mobile station, the selected transmission power control signal from the radio base station communicating therewith; and

controlling, in said mobile station, the transmission power on the basis of the selected transmission power control signal.

5. A host station for use in a mobile communication system including a plurality of radio base stations, each of said radio base stations including, a receiver for receiving an upward communication channel signal from said mobile station;

a processor for calculating, on the basis of the upward communication channel signal, a transmission power control signal for controlling transmission power for said mobile station;

a transmitter for transmitting the transmission power control signal to said host station;

a receiver for receiving a selected transmission power control signal from said host station; and

a transmitter for transmitting the selected transmission power control signal to said mobile station, said host station comprising;

a receiver for receiving the transmission power control signals from said radio base stations as received transmission power control signals;

a selector for selecting, as the selected transmission power control signal, one of the received transmission power control signals that provides the lowest transmission power for said mobile station among the received power control signals; and

a transmitter for transmitting the selected transmission power control signal to a particular one of the radio base stations that communicates with said mobile station.

6. A radio base station carrying out radio communication with a mobile station in a mobile communication system comprising a host station, said radio base station being one of a plurality of radio base stations in said mobile communication system, said radio base station comprising:

a receiver for receiving an upward communication channel signal from said mobile station;

a processor for calculating, on the basis of the upward communication channel signal, a transmission power control signal for controlling transmission power for said mobile station;

a transmitter for transmitting the transmission power control signal to said host station;

a receiver in said host station for receiving the transmission power control signals from said radio base stations as received transmission power control signals;

a selector in said host station for selecting, as a selected transmission power control signal, one of the received transmission power control signals that provides the lowest transmission power for said mobile station among the received power control signals; and

a transmitter for transmitting the selected transmission power control signal to said mobile station via a base station corresponding to the selected transmission power control signal,

wherein the radio base stations are connected via a private line, and transmission and reception of said power control signal occurs via said private line.