CODE DIVISION MULTIPLE ACCESS MOBILE COMMUNICATION SYSTEM

• US 20100278148A1
• Filed: 07/14/2010
• Published: 11/04/2010
• Est. Priority Date: 05/13/1998
• Status: Active Grant

• Current Assignee: FIPA Frohwitter Intellectual Property AG
• Original Assignee: FIPA Frohwitter Intellectual Property AG
• Inventors: Doi, Nobukazu, Yano, Takashi, Suzuki, May
• Granted Patent: US 8,335,245 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/708 Parallel implementation
• 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: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

In a mobile communication system using a code division multiple access (CDMA) method, spreading code detection and frame/slot timing synchronization (cell search) is conducted by using a long code masked symbol. The spreading factor of the long code masked symbol is set to a value lower than spreading factors of other ordinary symbols. As a result, it becomes possible to reduce the circuit scale and power dissipation of the mobile terminal and raise the speed of cell search.

Claims

1. A mobile terminal for use in a code division multiple access, CDMA, mobile communication system, the mobile terminal comprising:

an antenna which receives a received signal; and

a cell search circuit which receives, as an input signal, a baseband perch channel signal included in the received signal, the perch channel signal including a control signal spread by a long code and a first short code in a data symbol section of one slot section on the perch channel, a repetition of a second search code being provided in a long code masked symbol section of said one slot section, and a first search code, also being provided in said long code masked symbol section,

wherein the cell search circuit includes a timing synchronization part, a second search code detection part and a long code detection part,

the timing synchronization part including a first search code generator arranged to generate the first search code in response to a timing signal and a correlator for maximizing a correlation value between said received signal and the generated first search code,

the second search code detection part including a code generator arranged to generate successive candidate second search codes and a processor for determining which of the candidate second search codes corresponds to the second search code of the base station by analyzing correlation values of the candidate second search code and the received signal within the long code masked symbol section, and

the long code detection part including a code generator arranged to generate candidate long codes and a code generator arranged to generate the first short code and a processor for determining which of the candidate long codes corresponds to the long code by analyzing correlation values of the candidate long code multiplied by the first short code and the received signal within the data symbol section, and

wherein said first and second search codes have a spreading factor shorter than the long code and the first short code.

2. The mobile terminal according to claim 1, wherein the terminal is arranged to detect the long code by dispreading using all long codes belonging to a group associated with the detected second search code.

3. A mobile terminal used in a code division multiple access mobile communication system, in which a base station transmits a control signal via perch channels formed such that a long period code assigned to said base station and a first short period code are mapped in a first section of one slot of said perch channel and a predetermined short period code is mapped in a second section of said one slot, said mobile terminal comprising:

an RF unit for converting a received signal of a carrier frequency received from an antenna to a baseband signal; and

a correlator connected to said RF unit and arranged to receive said baseband signal, the correlator including a code generator for generating said predetermined short period code and arranged to calculate a correlation value for said baseband signal by using said predetermined short period code to establish slot timing synchronization,

wherein a symbol length of said predetermined short period code has a smaller value than a symbol length of said first short period, and

wherein in said second section are mapped a second short period code, and a third short period code being one of a plurality of short period codes each corresponding to classification of the long period code spreading said first section.

6. A mobile terminal according to claim 3, wherein said second short period code is a short period code common to base stations included in the mobile communication system, and said third short period code is one of a plurality of short period spreading codes each corresponding to classification of said long period code.

4. A mobile terminal used in a code division multiple access mobile communication system in which a base station transmits a control signal via perch channels formed such that a long period code assigned to said base station and a first short period code is mapped in a first section of one slot of said perch channel and a predetermined short period code is mapped in a second section of said one slot, said mobile terminal comprising:

an RF unit for converting a received signal of a carrier frequency received from an antenna to a baseband signal; and

a correlator for receiving input of said baseband signal and calculating a correlation value of said baseband signal using a generated predetermined short period code, wherein the predetermined short period code has a length smaller than a length of said long period code of said control signal.

5. A mobile terminal used in a code division multiple access mobile communication system in which a base station transmits a control signal via perch channels formed such that a long period code assigned to said base station and a first short period code is mapped in a first section of one slot of said perch channel and a second short period code and a third short period code are mapped in a second section of said one slot, comprising:

an RF unit for converting a received signal of a carrier frequency received from an antenna to a baseband signal; and

a correlator including a code generator arranged to generate said second short period code in response to a timing signal for calculating a correlation value for said baseband signal, wherein said received signal includes a control signal, said long period code being assigned to said base station and said first short period code being assigned to each channel of said base station, and said second short period code having a spreading factor smaller than said first short period code and said third short period code having a spreading factor not greater than said first short period code, and wherein said correlator filter calculates the correlation value for said control signal by use of said second short period code.

7. A mobile terminal used in a code division multiple access mobile communication system, comprising:

a RF unit for converting a received signal of a carrier frequency received from an antenna to a received signal of a baseband; and

a correlator including a code generator arranged to generate a predetermined short period code in response to a control signal, the correlator for calculating a correlation value for said received signal using said predetermined short period code,

wherein said received signals includes a control signal, a first section of one slot of said control signal having mapped in it a long period code assigned to said base station and a short period code assigned to each channel of said base station, a second section of said one slot having mapped in it said predetermined short period spreading code, and a period of said predetermined short period code is smaller than a period of said short period code mapped in said first section.