Base station, mobile station, and synchronization channel transmission method

A synchronization channel transmission method in a radio communication system including a base station communicating with a mobile station by using OFDM for downlink, comprising:

• a sequence selecting step, performed by the base station, of selecting multiple synchronization signal sequences;
• a synchronization signal generating step, performed by the base station, of generating a secondary synchronization channel based on a part of the selected synchronization signal sequences and another part of the selected synchronization signal sequences;
• and
• a transmitting step, performed by the base station, of transmitting the secondary synchronization channel,
• wherein the mobile station detects cell-specific information based on the secondary synchronization channel.

A base station used in a mobile communication system, comprising:

• a channel generating unit configured to generate synchronization channels to be used in a cell search performed by a user equipment;
• and
• a transmitting unit configured to wirelessly transmit a signal including the synchronization channels, wherein
• the synchronization channels include a primary synchronization channel for detecting a reception timing and a secondary synchronization channel including cell-specific information;
• the secondary synchronization channel is composed of a combination of different short codes selected from multiple combinations of short codes;
• correspondence among the combinations of short codes, cell identification information, and frame synchronization timings is stored in a memory;
• and
• the combinations of short codes are determined such that secondary synchronization channels including a same short code are not transmitted from adjacent cells at two or more of the frame synchronization timings in succession.

A user equipment communicating via a base station in a mobile communication system, comprising:

• a receiving unit configured to receive a signal including synchronization channels;
• a detecting unit configured to detect reception timing information based on a primary synchronization channel included in the synchronization channels;
• and
• an identification unit configured to identify at least cell identification information based on a secondary synchronization channel included in the synchronization channels, wherein
• the secondary synchronization channel is composed of a combination of different short codes selected from multiple combinations of short codes;
• correspondence among the combinations of short codes, the cell identification information, and frame synchronization timings is stored in a memory;
• and
• the combinations of short codes are determined such that secondary synchronization channels including a same short code are not transmitted from adjacent cells at two or more of the frame synchronization timings in succession.

A method used in a mobile communication system, comprising the steps of:

• wirelessly transmitting a signal including synchronization channels from a base station to a user equipment;
• detecting candidates of a frame synchronization timing based on a primary synchronization channel included in the synchronization channels;
• and
• extracting a secondary synchronization channel from the synchronization channels and identifying multiple combinations of short codes, cell identification information, and the frame synchronization timing, wherein
• the secondary synchronization channel is composed of a combination of different short codes selected from the combinations of short codes;
• and
• the combinations of short codes are determined such that secondary synchronization channels including a same short code are not transmitted from adjacent cells at two or more of the frame synchronization timings in succession.