Signal format in multi-carrier cdma transmission system

• US 20020136176A1
• Filed: 09/05/2001
• Published: 09/26/2002
• Est. Priority Date: 01/05/2000
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Sawahashi, Mamoru, Abeta, Sadayuki, Atarashi, Hiroyuki
• Granted Patent: US 7,286,508 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal

Abstract

A multi-carrier CDMA transmission system signal format that reproduces data symbols, aligns the reproduced data symbols along a frequency axis, multiplies the reproduced data symbols by a spreading code, and conducts multiplex transmission of data using a plurality of sub-carriers of different frequencies, in which a common pilot symbol inserted in a transmission signal for estimating a variation in channel and estimating a channel common to each of a plurality of users, and a user-specific individual pilot symbol transmitted along a channel different from the above-described channel.

Claims

1. In a multi-carrier CDMA transmission system that reproduces data symbols, aligns the reproduced data symbols along a frequency axis, multiplies the reproduced data symbols by a spreading code and performs multiplex transmission of data using a plurality of sub-carriers of different frequencies, a signal format of a transmission signal used when inserting a pilot symbol for estimating a variation of channel and performing synchronous detection,

the pilot symbol including:

a common pilot symbol for the purpose of estimating a channel common to each user; and

a user-specific pilot symbol that performs communication in a channel different from the above described channel.

2. The multi-carrier CDMA transmission system signal format as claimed in claim 1, wherein all or some of the plurality of sub-carriers used in signal transmission are used as sub-carriers when spreading the pilot symbol along a frequency axis.

3. The multi-carrier CDMA transmission system signal format as claimed in claim 1 or claim 2, wherein the pilot symbols are orthogonal on the spread frequency axis, and further, pilot symbol sequences are orthogonal on a time axis.

4. The multi-carrier CDMA transmission system signal format as claimed in claim 1, wherein:

the signal format allots some of the plurality of sub-carriers used in the signal transmission to the pilot symbols discretely along the frequency axis and inserts a symbol sequence that multiplexes the common pilot symbol and the individual pilot symbol using a spreading signal in a direction of the time axis into the sub-carriers allotted to the pilot symbols.

5. The multi-carrier CDMA transmission system signal format as claimed in claim 4, wherein the spreading code for the common pilot symbol and the spreading code for the specific pilot symbol are orthogonal.