Mobile communication system, channel synchronization establishing method, and mobile station

• US 20030152178A1
• Filed: 02/14/2003
• Published: 08/14/2003
• Est. Priority Date: 02/14/2002
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Tanno, Motohiro, Sawahashi, Mamoru, Atarashi, Hiroyuki
• Granted Patent: US 7,315,566 B2
• Time in Patent Office: Days
• US Class Current: 375/354
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols

Abstract

A mobile communication system 1 according to the present invention comprises base station 30 and mobile station 10. The base station 30 sends a pilot symbol sequence known to the mobile station 10, to the mobile station 10, using a plurality of carriers for downward channels, and performs communication with the mobile station 10 while multiplying the channels by frequencywise same scrambling codes every symbol period. The mobile station 10 is provided with a peak detector 17 for calculating cross correlation allowing for a phase difference of the scrambling codes, between frequencywise pilot symbol sequences received from the base station 30, thereby detecting a radio frame boundary.

Claims

1. A mobile communication system which comprises a base station and a mobile station and in which the base station transmits a pilot symbol sequence known to the mobile station, to the mobile station, using a plurality of carriers for downward channels, and performs communication with the mobile station while multiplying the channels by frequencywise same scrambling codes every symbol period,

wherein the mobile station comprises boundary detecting means for calculating cross correlation allowing for a phase difference of the scrambling codes, between frequencywise pilot symbol sequences received from the base station, thereby detecting a radio frame boundary.

2. The mobile communication system according to claim 1, wherein the base station comprises:

control information transmitting means for sending a plurality of pilot symbol sequences in one radio frame and for transmitting control information to the mobile station, using the phase difference of a plurality of scrambling codes by which the plurality of pilot symbol sequences are multiplied.

3. The mobile communication system according to claim 2, wherein said control information is a scrambling code group used by the base station.

4. The mobile communication system according to claim 1, wherein said phase difference, on a frequency interval basis, is a value falling within a scope of a coherent bandwidth.

5. The mobile communication system according to claim 2, wherein said control information transmitting means transmits the control information, using plural types of pilot symbol sequences.

6. The mobile communication system according to claim 5, wherein said pilot symbol sequences are pseudo-random sequences.

7. The mobile communication system according to claim 5, wherein said control information is a scrambling code group used by the base station.

8. The mobile communication system according to claim 1, wherein the boundary detecting means of the mobile station calculates the cross correlation between frequencywise pilot symbol sequences received from the base station and detects the radio frame boundary, using values resulting from normalization of cross correlation values by reception powers of the pilot symbol sequences.

9. The mobile communication system according to claim 1, wherein said boundary detecting means calculates the cross correlation between a pilot symbol sequence separated by FFT processing and a pilot symbol sequence resulting from multiplication by scrambling codes with a delay of a phase difference of one symbol period with respect to the pilot symbol sequence separated by FFT processing, thereby detecting the radio frame boundary.

10. The mobile communication system according to claim 3, wherein said boundary detecting means calculates the cross correlation between a pilot symbol sequence separated by FFT processing and pilot symbol sequences resulting from multiplication by scrambling codes with delays of phase differences of a predetermined symbol period with respect to the pilot symbol sequence separated by FFT processing, thereby detecting the radio frame boundary, and

wherein said control information transmitting means transmits scrambling code groups corresponding to said phase differences.

11. A channel synchronization establishing method in a mobile communication system which comprises a base station and a mobile station and in which the base station transmits a pilot symbol sequence known to the mobile station, to the mobile station, using a plurality of carriers for downward channels, and performs communication with the mobile station while multiplying the channels by frequencywise same scrambling codes every symbol period, said channel synchronization establishing method comprising:

a boundary detecting step wherein the mobile station calculates cross correlation allowing for a phase difference of the scrambling codes, between frequencywise pilot symbol sequences received from the base station, thereby detecting a radio frame boundary.

12. The channel synchronization establishing method according to claim 11, further comprising a control information transmitting step wherein the base station sends a plurality of pilot symbol sequences in one radio frame and transmits control information to the mobile station, using the phase difference of a plurality of scrambling codes by which the plurality of pilot symbol sequences are multiplied.

13. The channel synchronization establishing method according to claim 12, wherein said control information is a scrambling code group used by the base station.

14. The channel synchronization establishing method according to claim 11, wherein said phase difference, on a frequency interval basis, is a value falling within a scope of a coherent bandwidth.

15. The channel synchronization establishing method according to claim 12, wherein said control information transmitting step is to transmit the control information, using plural types of pilot symbol sequences.

16. The channel synchronization establishing method according to claim 15, wherein said pilot symbol sequences are pseudo-random sequences.

17. The channel synchronization establishing method according to claim 15, wherein said control information is a scrambling code group used by the base station.

18. The channel synchronization establishing method according to claim 11, wherein in said boundary detecting step the mobile station calculates the cross correlation between frequencywise pilot symbol sequences received from the base station and detects the radio frame boundary, using values resulting from normalization of cross correlation values by reception powers of the pilot symbol sequences.

19. The channel synchronization establishing method according to claim 11, wherein in said boundary detecting step the mobile station calculates the cross correlation between a pilot symbol sequence separated by FFT processing and a pilot symbol sequence resulting from multiplication by scrambling codes with a delay of a phase difference of one symbol period with respect to the pilot symbol sequence separated by FFT processing, thereby detecting the radio frame boundary.

20. The channel synchronization establishing method according to claim 13, wherein in said boundary detecting step the mobile station calculates the cross correlation between a pilot symbol sequence separated by FFT processing and pilot symbol sequences resulting from multiplication by scrambling codes with delays of phase differences of a predetermined symbol period with respect to the pilot symbol sequence separated by FFT processing, thereby detecting the radio frame boundary, and

wherein in said control information transmitting step the base station transmits scrambling code groups corresponding to said phase differences.

21. A mobile station which receives a pilot symbol sequence known to the mobile station, from a base station, using a plurality of carriers for downward channels from the base station to the mobile station, and which performs communication with the base station, using the channels multiplied by frequencywise same scrambling codes every symbol period, said mobile station comprises:

boundary detecting means for calculating cross correlation allowing for a phase difference of the scrambling codes, between frequencywise pilot symbol sequences received from the base station, thereby detecting a radio frame boundary.

22. The mobile station according to claim 21, wherein said boundary detecting means calculates the cross correlation between frequencywise pilot symbol sequences received from the base station and detects the radio frame boundary, using values resulting from normalization of cross correlation values by reception powers of the pilot symbol sequences.

23. The mobile station according to claim 21, wherein said boundary detecting means calculates the cross correlation between a pilot symbol sequence separated by FFT processing and a pilot symbol sequence resulting from multiplication by scrambling codes with a delay of a phase difference of one symbol period with respect to the pilot symbol sequence separated by FFT processing, thereby detecting the radio frame boundary.