Method for acquiring a cell site station in asynchronous CDMA cellular communication systems

• US 6,289,007 B1
• Filed: 08/20/1998
• Issued: 09/11/2001
• Est. Priority Date: 02/05/1998
• Status: Expired due to Term

• Current Assignee: Korea Telecom (KT Corporation)
• Original Assignee: Korea Telecom (KT Corporation)
• Inventors: You, Heung Ryel, Kim, Dong In, Lee, Yu Ro, Kim, Yeon Soo
• Primary Examiner(s): NGO, RICKY QUOC
• Application Number:
  US09/136,423
• Time in Patent Office: 1,118 Days
• Field of Search: 370/328, 370/329, 370/331, 370/335, 370/342, 370/441, 370/514, 370/515, 455/436, 455/437, 455/438, 455/446, 455/449
• US Class Current: 370/331
• CPC Class Codes: H04B 1/70735 Code identification H04B1/7083 takes precedence
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04W 48/12 using downlink control channel

Abstract

A group code and a cell code are multiplexed and then used as a pilot code for discriminating a base station in asynchronous cellular CDMA (Code Division Multiple Access) communication systems. Using the multiplexed code, interferences are reduced in case of using two pilot codes. A method for acquiring a cell site station in asynchronous CDMA (Code Division Multiple Access) communication systems including a base station controller, a plurality of mobile stations and base stations, and discriminating the base stations by using different sequences, the method including the steps of: a) assigning a group code of the cell as a pilot code of an inphase channel of the base stations; b) assigning a cell code of the cell as a pilot code of a quadrature channel of the base stations; and c) multiplexing the pilot codes of inphase channel and the quadrature channel, and generating an inphase/quadrature pilot code.

Claims

1. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system comprising a base station controller, a plurality of mobile stations and base stations, and discriminating the base stations by using different sequences, the method comprising:

a) assigning a group code of the cell as a pilot code of an inphase channel of the base station;

b) assigning a cell code of the cell as a pilot code of a quadrature channel of the base station; and

c) multiplexing the pilot codes of the inphase channel and the quadrature channel, and generating an inphase/quadrature pilot code.

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

d) synchronizing, at the mobile station, with the group code of the base station by searching the inphase channel of the inphase/quadrature pilot code;

e) synchronizing, at the mobile station, with the cell code of the base station by searching the quadrature channel of the inphase/quadrature pilot code; and

f) synchronizing, at the mobile station, with a frame by searching code offsets of the frame.

3. A method as claimed in claim 2, wherein said step c) comprises:

performing correlation of a plurality of the inphase pilot codes in parallel; and

performing correlation of a plurality of the quadrature pilot codes after delaying the inphase/quadrature pilot codes by a number of chips correlated at the same time.

4. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system comprising a base station controller, a plurality of mobile stations and base stations, and discriminating the base stations by using different sequences, the method comprising:

a) assigning a group code of the cell as a pilot code of a quadrature channel of the base station;

b) assigning a cell code of the cell as a pilot code of an inphase channel of the base station; and

c) multiplexing the pilot codes of the inphase channel and the quadrature channel, and generating an inphase/quadrature pilot code.

5. A method as claimed in claim 4, further comprising:

d) synchronizing, at the mobile station, with the group code of the base station by searching the quadrature channel of the inphase/quadrature pilot code

e) synchronizing, at the mobile station, with the cell code of the base station by searching the inphase channel of the inphase/quadrature pilot code; and

f) synchronizing, at the mobile station, with a frame by searching code offsets of the frame.

6. A method as claimed in claim 5, wherein said step c) comprises:

performing correlation of a plurality of the quadrature pilot codes in parallel; and

performing correlation of a plurality of the inphase pilot codes after delaying the inphase/quadrature pilot codes by a number of chips correlated at the same time.

7. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system with a hierarchical cell structure, wherein the system includes a base station controller, a plurality of mobile stations and base stations, wherein the hierarchical cell structure comprises a plurality of macro cells and micro cells, wherein each base station uses a different sequence, the method comprising:

a) assigning a group code of each macro cell as a pilot code of an inphase channel of the base station in the macro cell, wherein the mobile station discriminates a group of the base station in the macro cell using the group code;

b) assigning a cell code of each macro cell as a pilot code of a quadrature channel of the base station in said macro cell;

c) assigning a group code of each micro cell as a pilot code of an inphase channel of the base station in the micro cell, wherein the group code of the micro cell is the same as the cell code of the macro cell; and

d) assigning a cell code of each said micro cell as a pilot code of a quadrature channel of the micro cell, wherein the cell code of the micro cell is generated in accordance with the group code of the macro cell.

8. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system with a hierarchical cell structure, wherein the system includes a base station controller, a plurality of mobile stations and base stations, wherein the hierarchical cell structure comprises a plurality of macro cells and micro cells, wherein each base station uses a different sequence, the method comprising:

a) assigning a group code of each macro cell as a pilot code of a quadrature channel of the base station in the macro cell, wherein the mobile station discriminates a group of the base station in the macro cell using the group code;

b) assigning a cell code of each macro cell as a pilot code of an inphase channel of the base station in said macro cell;

c) assigning a group code of each micro cell as a pilot code of a quadrature channel of the base station in the micro cell, wherein the group code of the micro cell is the same as the cell code of the macro cell; and

d) assigning a cell code of each micro cell as a pilot code of an inphase channel of the macro cell, wherein the cell code of the micro cell is generated in accordance with the group code of the macro cell.

9. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system with a hierarchical cell structure during a handoff which transfers communications between the mobile station and an old base station in a macro cell to communications between a mobile station and a new base station in a micro cell, wherein each base station uses a different sequence, the method comprising:

a) searching for synchronization of a group code which is a pilot code of an inphase channel in the micro cell;

b) searching for a cell code which is a pilot code of a quadrature channel in the micro cell; and

c) searching for frame synchronization.

10. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system with a hierarchical cell structure during a handoff which transfers communications between a mobile station and an old base station in a macro cell to communications between the mobile station and a new base station in a micro cell, wherein each base station uses a different sequence, the method comprising:

a) searching for synchronization of a group code which is a pilot code of a quadrature channel in the micro cell;

b) searching for a cell code which is a pilot code of an inphase channel in the micro cell; and

c) searching for frame synchronization.

11. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system with a hierarchical cell structure during a handoff which transfers communications between the mobile station and an old base station in a micro cell to communications between a mobile station and a new base station in a macro cell, wherein each base station uses a different sequence, the method comprising:

a) searching for synchronization of a group code which is a pilot code of an inphase channel in the macro cell;

b) searching for a cell code which is a pilot code of a quadrature channel in the macro cell; and

c) searching for frame synchronization.

12. A method for acquiring a cell site station in an asynchronous CDMA (Code Division Multiple Access) communication system with a hierarchical cell structure during a handoff which transfers communications between the mobile station and an old base station in a micro cell to communications between a mobile station and a new base station in a macro cell, wherein each base station uses a different sequence, the method comprising:

a) searching for synchronization of a group code which is a pilot code of a quadrature channel in the macro cell;

b) searching for a cell code which is a pilot code of an inphase channel in the macro cell; and

c) searching for frame synchronization.