CDMA transmission apparatus

• US 6,661,783 B1
• Filed: 03/09/1999
• Issued: 12/09/2003
• Est. Priority Date: 03/10/1998
• Status: Expired due to Term

• Current Assignee: Nitetek Licensing LLC (IP Edge LLC)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Watanabe, Masatoshi, Hayashi, Masaki, Kato, Osamu
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/264,856
• Time in Patent Office: 1,736 Days
• Field of Search: 370/320, 370/335, 370/342, 370/441, 370/474, 370/208, 370/209
• US Class Current: 370/335
• CPC Class Codes: H04J 13/0048 Walsh
• CPC Class Codes: H04J 13/12 Generation of orthogonal codes
• CPC Class Codes: H04W 52/267 taking into account the information rate

Abstract

During asymmetric communications using only the uplink, frame configuration section 109 transmits a signal made up of only pilot signals and transmission power control bits assembled into frames. The transmission power control method is the same as that for normal communications. In this case, since signals transmitted on the downlink are only pilot signals and transmission power control bits, it is possible to reduce the transmission rate considerably and transmit signals with its transmission power reduced by transmission signal amplitude control section 111. In this case, a long hierarchic orthogonal type spreading code is set as the spreading code used by spreader 110.

Claims

1. A CDMA mobile communication system, wherein a base station apparatus, when performing asymmetric communications, transmits known reference signals and transmission power control bits at a lower transmission rate than a transmission rate when symmetric communications are performed, and

a mobile station receives said transmission power control bits and determines transmission power based on said transmission power control bits;

wherein a code length of a spreading code longer than a code length of spreading codes for symmetric communications is used as the spreading code for the downlink of asymmetric communications and said longer spreading code is orthogonal to spreading codes used for other asymmetric communication lines.

2. The CDMA mobile communication system according to claim 1, wherein a hierarchic orthogonal type spreading code is used as a spreading code for a downlink, and a hierarchic orthogonal type spreading code is a spreading code of a hierarchy which contains spreading codes with a length that is longer than spreading codes used for symmetric communication downlinks, said spreading code being orthogonal to spreading codes used for other asymmetric communication lines.

3. A spreading code selection method, which selects as the spreading code for asymmetric communications, a hierarchic orthogonal type spreading code which is a spreading code of a hierarchy which contains spreading codes of a longer length than spreading codes used for symmetric communication lines and is orthogonal to spreading codes used for other asymmetric communication lines.

4. A CDMA mobile communication method, when performing asymmetric communications, comprising:

a base station apparatus spreading known reference signals and transmission power control bits by spreading codes with a length that is longer than spreading codes used for symmetric communications, and transmitting spreaded known reference signals and a spreaded transmission power control bits at a lower transmission rate than a transmission rate when symmetric communications are performed;

a mobile station apparatus receiving said transmission power control bits; and

said mobile station apparatus determining transmission power based on said transmission power control bits.

5. The CDMA mobile communication method according to claim 4, wherein a hierarchic orthogonal type spreading code is used as a spreading code for a downlink and a spreading code of a hierarchy which contains spreading codes with a length longer than spreading codes used on a symmetric communication downlink is used as the spreading code for an asymmetric communication downlink, said spreading code of a hierarchy of spreading codes with a longer length being orthogonal to spreading codes used for other asymmetric communication lines.

6. A CDMA communication apparatus, comprising:

a frame assembler that assembles frames with known reference signals and transmission power bits during a communication;

a transmission rate controller that sets a lower transmission rate of a transmission signal made up of said known reference signals and said transmission power bits than a transmission rate for a symmetric communication, and

a spreading code determiner that determines a spreading code for spreading the transmission signal made up of said known reference signals and said transmission power bits, the spreading code having a longer code length than a spreading code for a symmetric communication line.

7. The CDMA communication apparatus of claim 6, wherein said spreading code determiner uses a hierarchical orthogonal type spreading code as a spreading code, and determines a spreading code of a hierarchy which contains spreading codes with a length longer than spreading codes used for symmetric communication lines as a spreading code that spreads said transmission signal of said known reference signals and said transmission power bits.

8. The CDMA communication apparatus of claim 6, wherein said spreading code determiner selects a spreading code which is orthogonal to spreading codes used for other asymmetric communication lines.

9. A base station apparatus, comprising:

a CDMA communication apparatus, wherein said CDMA communication apparatus includes;

a frame assembler that assembles frames with known reference signals and transmission power bits during an asymmetric communication;

a transmission rate controller that sets a transmission rate of a transmission signal made up of said known reference signals and said transmission power bits that is lower than a transmission rate for a symmetric communication; and

a spreading code determiner that determines a spreading code for spreading the transmission signal made up of said known reference signals and said transmission power bits, the spreading code having a longer code length than a spreading code for a symmetric communication line.

10. A mobile station apparatus which performs a radio communication with a base station apparatus, comprising:

a CDMA communication apparatus, having;

a frame assembler that assembles frames with known reference signals and transmission power bits during an asymmetric communication;

a transmission rate controller that sets a transmission rate of a transmission signal made up of said known reference signals and said transmission power bits that is lower than a transmission rate for a symmetric communication; and

a spreading code determiner that determines a spreading code for spreading the transmission signal made up of said known reference signals and said transmission power bits, the spreading code having a longer code length than a spreading code for a symmetric communication line.