Code-division multiple-access receiver with sequential interference-canceling architecture
First Claim
1. A method of receiving a code-division multiple-access signal combining symbol values spread by a plurality of spreading codes, comprising the steps of:
- (a) converting said code-division multiple-access signal to a baseband signal;
(b) recognizing a boundary of a symbol in said baseband signal;
(c) generating a spreading code by which said symbol was spread, and a corresponding despreading code;
(d) generating a symbol value input of said symbol, by using said baseband signal and said despreading code;
(e) estimating an interference signal, by using said spreading code to spread the symbol value input;
(f) modifying said baseband signal by subtracting said interference signal; and
(g) repeating said steps (b) through (f) at least once for each symbol value combined in said code-division multiple-access signal.
2 Assignments
0 Petitions
Accused Products
Abstract
A code-division multiple-access receiver carries out the following steps whenever it recognizes a symbol boundary in the received baseband signal. First, using the despreading code of the relevant station, it estimates the value of the symbol. Next, using the spreading code of the station, it estimates an interference signal, and modifies the baseband signal by subtracting the interference signal. These steps can be iterated for each symbol. The iterations can be organized into stages, with estimated symbol values from one stage passed to the next stage for use in estimating new symbol values in that next stage. At the end, the remaining baseband signal can be used to adjust the final estimated symbol values.
161 Citations
60 Claims
-
1. A method of receiving a code-division multiple-access signal combining symbol values spread by a plurality of spreading codes, comprising the steps of:
-
(a) converting said code-division multiple-access signal to a baseband signal; (b) recognizing a boundary of a symbol in said baseband signal; (c) generating a spreading code by which said symbol was spread, and a corresponding despreading code; (d) generating a symbol value input of said symbol, by using said baseband signal and said despreading code; (e) estimating an interference signal, by using said spreading code to spread the symbol value input; (f) modifying said baseband signal by subtracting said interference signal; and (g) repeating said steps (b) through (f) at least once for each symbol value combined in said code-division multiple-access signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 42, 43)
-
-
19. A code-division multiple-access receiver for receiving a code-division multiple-access signal combining signals of a plurality of stations, each station having a different spreading code and a corresponding despreading code, comprising:
-
a front-end circuit for converting said code-division multiple-access signal to a baseband signal; a controller coupled to said front-end circuit, for recognizing symbol boundaries in said baseband signal; and a baseband processor coupled to said front-end circuit, for receiving said baseband signal, storing successive one-symbol portions of said baseband signal, despreading said one-symbol portions of said baseband signal to generate estimated symbol values, respreading said estimated symbol values to generate estimated interference signals, and modifying said baseband signal by subtracting said estimated interference signals, these processes of despreading, respreading, and modifying being carried out in a cyclic order responsive to symbol boundaries recognized by said controller. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 44, 45, 46, 47, 48, 50)
-
-
49. A code-division multiple-access receiver for receiving a code-division multiple-access signal combining signals of a plurality of stations, each station having a different spreading code and a corresponding despreading code, comprising:
-
a front-end circuit for converting said code-division multiple-access signal to a baseband signal; a shift register coupled to said front-end circuit, for receiving, storing, and shifting said baseband signal; a controller coupled to said front-end circuit, for recognizing symbol boundaries in said baseband signal; a symbol memory for storing estimated symbol values; and a baseband processor coupled to said shift register and said symbol memory, for reading from said shift register a part of said baseband signal corresponding to one symbol, generating a spreading code by which said symbol was spread, generating a corresponding despreading code, using said part of said baseband signal and said despreading code to generate an estimated symbol value storing said estimated symbol value in said symbol memory, using said spreading code to generate an estimated interference signal, and modifying said part of said baseband signal in said shift register by subtracting said estimated interference signal. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
-
Specification