Control method of searching neighboring cells, mobile station, and mobile, communication system

• US 20040071119A1
• Filed: 09/18/2003
• Published: 04/15/2004
• Est. Priority Date: 09/06/1999
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Onoe, Seizo, Yunoki, Kazufumi, Ishikawa, Yoshihiro, Higashi, Akihiro
• Granted Patent: US 7,437,152 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 1/70735 Code identification H04B1/7083 takes precedence
• CPC Class Codes: H04B 1/7083 Cell search, e.g. using a three-step approach
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects
• CPC Class Codes: H04W 36/00835 Determination of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A control method of searching for a neighboring cell of a mobile station communicating with a base-station is provided in a direct sequence CDMA mobile communication system which transmits information by carrying out double modulation using a first spreading code group and a second spreading code. The first spreading code group includes spreading codes that have a same repetition period as an information symbol period and are used in common by the base stations, and the second spreading code has a repetition period longer than the information symbol period. The base stations are assigned different second spreading codes. The control method stores at least one second spreading code and its phase into a first table, which second spreading code corresponds to a perch channel whose second spreading code and phase are known; stores a second spreading code used by a neighboring base station into a second table; searches for a perch channel whose second spreading code and phase are unknown; and searches for a perch channel whose second spreading code and phase are known. The neighboring cell search method can save the power consumption and time required for the mobile station to carry out the cell search with preventing an increase in the total cost of the system.

Claims

1. A cell search control method in a CDMA mobile communication system including a mobile station which decides a base station the mobile station waits for or communicates with by receiving a perch channel transmitted from the base station, and which monitors a paging signal to the mobile station by means of intermittent reception in the idle mode, said cell search control method comprising the step of:

carrying out, in the mobile station, measurement of receiving quality of the perch channel in synchronization with timing of receiving the paging signal sent to the mobile station.

2. The cell search control method as claimed in claim 1, wherein the measurement of the receiving quality of the perch channel is carried out in the mobile station when a time period counted from a latest measurement of the receiving quality of the perch channel exceeds a predetermined value.

3. A CDMA mobile communication system including a mobile station communicating with a plurality of base stations, each of said base stations comprising:

perch channel transmitting means for transmitting a perch channel to the mobile station; and

paging signal transmitting means for transmitting a paging signal to the mobile station, and said mobile station comprising;

base station decision means for deciding a base station said mobile station waits for or communicates with through the perch channel by receiving the perch channel transmitted by said perch channel transmitting means;

paging signal reception decision means for deciding in an idle mode as to whether the paging signal transmitted to said mobile station by said paging signal transmitting means is received or not by intermittent reception; and

receiving quality measurement means for measuring the receiving quality of the perch channel, wherein

said receiving quality measurement means carries out the measurement of the receiving quality of the perch channel in synchronization with timing of receiving the paging signal when said paging signal reception decision means decides that the paging signal is received.

4. The CDMA mobile communication system as claimed in claim 3, wherein said mobile station further comprises counting means for counting a time period from a latest measurement of the receiving quality of the perch channel, and wherein said receiving quality measurement means carries out the measurement of the receiving quality of the perch channel when the time period counted by said counting means exceeds a predetermined value.

5. A mobile station in a CDMA mobile communication system communicating with a plurality of base stations, said mobile station comprising:

base station decision means for deciding a base station said mobile station waits for or communicates with through a perch channel by receiving the perch channel transmitted from the base station;

paging signal reception decision means for deciding in an idle mode as to whether the paging signal transmitted to said mobile station from the base station is received or not by intermittent reception; and

receiving quality measurement means for measuring the receiving quality of the perch channel, wherein

said receiving quality measurement means carries out the measurement of the receiving quality of the perch channel in synchronization with timing of receiving the paging signal when said paging signal reception decision means decides that the paging signal is received.

6. The mobile station as claimed in claim 5, further comprising counting means for counting a time period from a latest measurement of the receiving quality of the perch channel, wherein said receiving quality measurement means carries out the measurement of the receiving quality of the perch channel when the time period counted by said counting means exceeds a predetermined value.