Spectrum spread communication system

• US 6,765,895 B1
• Filed: 09/14/2000
• Issued: 07/20/2004
• Est. Priority Date: 03/15/1996
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Watanabe, Masatoshi
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/661,357
• Time in Patent Office: 1,405 Days
• Field of Search: 370/315, 370/320, 370/324, 370/328, 370/329, 370/331, 370/335, 370/342-345, 370/350, 370/503, 370/506-512, 370/514-516, 370/441, 370/318, 375/140-141, 375/145-147, 375/149, 455/422, 455/426, 455/450-452, 455/500, 455/501, 455/507, 455/509-514, 455/517, 455/524, 455/525
• US Class Current: 370/335
• 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: H04L 7/043 Pseudo-noise [PN] codes variable during transmission synchronisation of spread spectrum receivers H04B1/69
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal

Abstract

In base station side equipment, a control channel for transmitting control information and a communication channel for transmitting information to each mobile station are spread with different synchronizing codes before being superposed by operating a switch to switch the output of an adder over to the output of a synchronizing code generator. Further, a synchronizing code is periodically inserted in a signal by one symbol length and the signal is transmitted over the superposed channel. In a plurality of base station side equipment, moreover, the synchronizing code and its transmission period are equal and the transmission timing is asynchronous and independent. A synchronizing correlator in mobile station side equipment obtains the correlation value of the whole chip phase in a synchronizing code transmission period using the synchronizing code and decides a base station which is transmitting the synchronizing code at the greatest correlating peak position to the closest one and further extracts symbol timing from the peak position.

Claims

1. A spectrum spread communication system comprising:

a plurality of base stations including communication means utilized for a direct spread CDMA method as a multiple access method; and

a plurality of mobile stations including communication means utilized for the direct spread CDMA method as the multiple access method,

wherein said each base station includes transmission means for transmitting a spectrum-spread synchronizing code periodically during a term of synchronizing code transmission section and for transmitting spectrum-spread user information and spectrum-spread control information during a predetermined interval between said terms of synchronizing code transmission section, and

wherein said each mobile station includes means for acquiring symbol synchronization of said base stations by detecting correlation of said synchronizing code.

2. The spectrum spread communication according to claim 1,

wherein kind of synchronizing codes is common among all said base stations and a common transmission period is utilized in all the base stations,

wherein said each base station transmits the synchronizing code at different timing from each others, and

wherein said each mobile station detects the correlation of said synchronizing code over the whole phase of the synchronizing code transmission period to determine a closest base station which transmits the synchronizing code whose correlation value is the highest.

3. The spectrum spread communication system according to claim 1,

wherein sequence of synchronizing codes is common among all said base stations and a common transmission period is utilized in all the base stations,

wherein synchronizing code transmission timings are prevented from being overlapped at least at adjoining base stations, and

wherein said each mobile station detects the correlation of said synchronizing code over the whole phase of the synchronizing code transmission period to determine a closest base station which transmits the synchronizing code whose correlation value is the highest.

4. The spectrum spread communication system according to claim 1,

wherein said spectrum-spread control information is spread by a combination of short code and a long code,

wherein symbol length of said short code is equal to a synchronizing code length and symbol length of said long code is longer than that of said short code,

wherein a long code period is equal to a synchronizing code transmission period,

wherein said synchronizing code is transmitted at a leading end of said long code period, and

wherein each mobile station acquires long code synchronization by using the synchronizing code transmission period and a timing obtained by detecting the correlation of the synchronizing code.

5. The spread spectrum system according to claim 1,

wherein said transmission means transmits said synchronizing code and spectrum-spread control information serially and alternatively in a channel, and

wherein said transmission means transmits said synchronizing code and spectrum-spread user information corresponding to each user serially and alternately in each channel corresponding to each user.