Communication apparatus for code division multiple accessing mobile communications system

• US 6,377,613 B1
• Filed: 10/22/1999
• Issued: 04/23/2002
• Est. Priority Date: 10/23/1998
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kawabe, Manabu, Doi, Nobukazu, Hanaoka, Seishi
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Ha, Dac V.
• Application Number:
  US09/422,186
• Time in Patent Office: 914 Days
• Field of Search: 375/140, 375/141, 375/142, 375/143, 375/144, 375/150, 375/152, 375/267, 375/340, 375/347, 375/343, 370/335, 370/342, 370/441, 370/479, 370/532, 370/537, 370/540
• US Class Current: 375/142
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04B 2201/7071 with dynamic control of receiver resources

Abstract

To simplify the structure of the demodulator and reduce the hardware scale in a code division multiple accessing communication apparatus. A plurality of base band received signals are multiplexed in a time division manner, so that one matched filter executes path searching or a time division multiplexing processing is executed for demodulation in a despreader. Or path searching and demodulation for a plurality of codes are executed with time division multiplexing of outputs from a plurality of code generators.

Claims

1. A communication apparatus used for a code divisionmultiple accessing mobile communication system, comprising:

a radio frequency demodulator for demodulating a plurality of carrier frequency band signals received at a plurality of receiving antennas to a plurality of base band spread spectrum signals;

a multiplexer for multiplexing a plurality of said base band spread spectrum signals in a time division manner;

a matched filter for calculating a correlation between each of a plurality of said base band spread spectrum signals multiplexed in a time division manner and a spread code, thereby outputting a correlation value therebetween;

a peak detector for detecting the predetermined number of peak values selected from peak values of said correlation values in descending order of received power factor; and

a despreader for despreading a plurality of said base band spread spectrum signals using a spreading code whose phase is adjusted to a timing detected in said peak detector.

2. A communication apparatus according to claim 1;

wherein

said multiplexer divides one chip period into n periods (n=number of time division multiplexed periods) and outputs a base band spread spectrum signal received at each of said receiving antennas in each of said divided periods respectively.

3. A communication apparatus according to claim 1;

wherein

said matched filter is provided with a first shift register for shifting said base band spreading code and a second shift register for shifting said base band spread spectrum signal multiplexed in a time division manner; and

said second shift register shifts said base band spread spectrum signal multiplexed in a time division manner according to the number of n registers (n=number of time division multiplexed ones) while said first shift register shifts said spreading code by one register.

4. A communication apparatus according to claim 1;

wherein

a plurality of said receiving antennas include a receiving antenna composing a plurality of sectors.

5. A communication apparatus used for a code division multiple accessing mobile communication system, comprising:

a radio frequency demodulator for demodulating a plurality of carrier frequency band signals received at a plurality of receiving antennas to a plurality of base band spread spectrum signals;

a multiplexer for multiplexing a plurality of said base band spread spectrum signals in a time division manner;

a matched filter for calculating a correlation between each of a plurality of said time-division-multiplexed base band spread spectrum signals and each of a plurality of spreading codes, thereby outputting a correlation value therebetween;

a peak detector for detecting the predetermined number of peak values selected from a plurality of said correlation values for each of a plurality of said spreading codes in descending order of received power factor; and

a despreader for despreading each of a plurality of said base band spread spectrum signals using a spreading code whose phase is adjusted to a timing detected in said peak detector.

6. A communication apparatus according to claim 5;

wherein

said matched filter is provided with a plurality of first shift registers for shifting each of a plurality of said spreading codes, a selector for outputting each of a plurality of said spreading codes stored in a plurality of said first shift registers selectively, and a second shift register for shifting said baseband spread spectrum signal; and

said second shift register shifts each of said time-division-multiplexed base band spread spectrum signals according to the number of n registers (n=number of time division multiplexed ones) while said first shift register shifts each of said spreading codes by one register, and said selector outputs each of said spreading codes stored in a plurality of said first shift registers selectively while said second shift register shifts each of said time-division-multiplexed base band spread spectrum signals by one register.

7. A communication apparatus used for a code division multiple accessing mobile communication system, comprising:

a despreader for despreading a received signal at a plurality of specified timings; and

a rake combiner for rake-combining said signals received from said despreader and despread at a plurality of said timings; and

said despreader comprises;

a plurality of code generators for generating a plurality of spreading codes at a plurality of said timings respectively;

a multiplexer for multiplexing each of spreading codes generated from a plurality of said code generators in a time division manner;

a register for storing a correlation value between a received signal and said time division multiplexed spreading code for each spreading code;

a multiplier for multiplying said received signal by said time-division-multiplexed spreading code; and

an adder for adding a result of multiplication output from said multiplier to a correlation value stored in said register for storing a correlation value with said multiplied spreading code.

8. A communication apparatus according to claim 7;

wherein

a plurality of said spreading codes are spreading codes assigned to a plurality of terminals.

9. A communication apparatus according to claim 7;

wherein

a plurality of said spreading codes are spreading codes assigned to a plurality of different base stations or different sectors.

10. A communication apparatus used for a code division multiple accessing mobile communication system, comprising:

a despreader for despreading a received signal at a plurality of specified timings; and

a rake combiner for rake-combining said received signal received from said despreader and despread at a plurality of said timings; and

said despreader comprises;

a code generator;

a plurality of status registers for storing code data put into said code generator;

a multiplexer for multiplexing each of spreading codes generated from said code generator when code data stored in said status register is set in said code generator at one of said specified timings;

a register for storing a correlation value between said received signal and said time-division-multiplexed spreading code for each of said spreading codes;

a multiplier for multiplying said received signal by said time-division-multiplexed spreading code; and

an adder for adding a result of multiplication output from said multiplier to a correlation value stored in said register for storing a correlation value with said multiplied spreading code.

11. A communication apparatus used for a code division multiple accessing mobile communication system for transmitting and receiving a signal modulated by a quadrature phase shift keying (QPSK) method, comprising:

a radio frequency demodulator for demodulating a plurality of received carrier frequency band signals to In-phase signals (I signals) and quadrature-phase signals (Q signals) which are base band spread spectrum signals;

a multiplexer for multiplexing both of said I and Q signals in a time division manner;

a matched filter for calculating a correlation between I and Q signals multiplexed in a time division manner, and an I code for spreading said I signal and a Q code for spreading said Q signal, thereby outputting the result of each of said correlations;

a peak detector for detecting the predetermined number of peak values selected from among a plurality of said correlation peak values sequentially in descending order of received power factor respectively; and

a despreader for despreading each base band spread spectrum signal using a spreading code whose phase is adjusted to a timing detected in said peak detector.

12. A communication apparatus according to claim 11;

wherein

said received power is found as follows;

((I signal×

I code)+(Q signal×

Q code))²+((I signal×

Q code)−

(Q signal×

I code))².

13. A communication apparatus according to claim 11;

wherein

said matched filter is provided with a first register for shifting said I code, a second shift register for shifting said Q code, a selector for selecting between said I code and said Q code, and a second shift register for shifting both I and Q signals multiplexed in a time division manner;

said third register shifts both of said time-division-multiplexed I and Q signals by two registers while said first shift register shifts said I code and said second shift register shifts said Q code by one register respectively, and said selector selects said I code or said Q signal while said third register shifts both of said I and Q signals which are multiplexed in a time division manner by one register respectively.

14. A communication apparatus according to claim 11;

wherein

said despreader comprises;

an I code generator for generating an I code and a Q code generator for generating a Q code at said timing respectively;

a multiplexer for multiplexing both I and Q codes generated from said I code generator and from said Q code generator in a time division manner;

a first register for storing a correlation value between said I signal and said I code, a second register for storing a correlation value between said Q signal and said Q code, a third register for storing a correlation value between said I signal and said Q code, and a fourth register for storing a correlation value between said Q signal and said I code,

a multiplier for multiplying each of said time-division-multiplexed I and Q signals by each of said time-division-multiplexed I and Q codes; and

an adder for adding a result of multiplication output from said multiplier to a correlation value stored in a register corresponding to said result of multiplication.

15. A communication apparatus according to claim 11;

wherein

said despreader comprises;

a code generator;

a first status register for storing I code data and a second status register for storing Q code data, which are put into said code generator respectively;

a multiplexer for setting said I code data or said Q code data selectively in said code generator at said specified timing sequentially;

a first register for storing a correlation value between said I signal and said I code, a second register for storing a correlation value between said Q signal and said Q code, a third register for storing a correlation value between said I signal and said Q code, and a fourth register for storing a correlation value between said Q signal and said I code;

a multiplier for multiplying each of said time-division-multiplexed I and Q signals by each of said time-division-multiplexed I and Q codes; and

an adder for adding a result of multiplication output from said multiplier to a correlation value stored in a register corresponding to said result of multiplication.