Cellar system, mobile portable apparatus, base station apparatus, optimum path detecting method, and apparatus thereof

• US 6,590,888 B1
• Filed: 03/02/1999
• Issued: 07/08/2003
• Est. Priority Date: 03/04/1998
• Status: Expired due to Term

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Ohshima, Manabu
• Primary Examiner(s): Yao, Kwang Bin
• Assistant Examiner(s): Hoang, Thai D
• Application Number:
  US09/260,049
• Time in Patent Office: 1,589 Days
• Field of Search: 370/342, 370/335, 370/441, 375/142, 375/144, 375/147-148, 375/150
• US Class Current: 370/342
• CPC Class Codes: H04B 1/7073 Synchronisation aspects
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• 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 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas

Abstract

A cellar system using code divisional multiple access (CDMA) system is disclosed, that comprises a plurality of finger circuits, and a search engine portion having a reception level measuring portion for detecting reception levels from reception signals and comparing the reception levels with a predetermined threshold value, a plurality of inversely spreading portions for multiplying the reception signals by spread codes, an inner memory for storing correlation signals received from the plurality of inversely spreading portions, and a reception path timing generating portion for detecting reception paths from output signals of the inner memory and, generating a path timing, wherein the search engine portion determines whether or not to output a correlation signal of the inner memory to the reception path timing generating portion.

Claims

1. A cellular system using code divisional multiple access (CDMA) system, comprising:

a plurality of finger circuits; and

a search engine portion comprising;

a plurality of inversely spreading portions for multiplying reception signals by spread codes,

an inner memory for storing correlation signals received from said plurality of inversely spreading portions,

a reception level measuring portion for detecting reception levels from the reception signals, comparing the reception levels with a predetermined threshold value and outputting a compared result to said inner memory, and

a reception path timing generating portion for detecting reception paths from output signals of said inner memory and generating a path timing,

wherein said search engine portion determines whether or not to output a correlation signal of said inner memory to said reception path timing generating portion according to the compared result of said reception level measuring portion.

2. The cellar system as set forth in claim 1,

wherein the reception levels of the reception signals are measured for each frame of the reception signals, and

wherein when the reception levels of the reception signals in the current frame are lower than the predetermined threshold value, a correlation signal in the preceding frame is output from said inner memory.

3. The cellar system as set forth in claim 1,

wherein said plurality of finger circuits inversely spread the reception signals corresponding to the reception paths detected by said search engine portion and synchronously adds correlation output signals of said plurality of finger circuits.

4. The cellar system as set forth in claim 2,

wherein said plurality of finger circuits inversely spread the reception signals corresponding to the reception paths detected by said search engine portion and synchronously adds correlation output signals of said plurality of finger circuits.

5. A mobile portable apparatus using code divisional multiple access (CDMA) system, comprising:

a demodulating portion for demodulating reception signals to baseband signals; and

a search engine portion for selecting reception paths corresponding to multi-paths, said search engine portion comprising;

a plurality of inversely spreading portions for multiplying reception signals by spread codes,

an inner memory for storing correlation signals received from said plurality of inversely spreading portions,

a reception level measuring portion for detecting reception levels from the reception signals, comparing the reception levels with a predetermined threshold value and outputting a compared result to said inner memory, and

a reception path timing generating portion for detecting reception paths from output signals of said inner memory and generating a path timing,

wherein said search engine portion determines whether or not to output a correlation signal of said inner memory to said reception path timing generating portion according to the compared result of said reception level measuring portion.

6. The mobile portable apparatus as set forth in claim 5,

wherein the reception levels of the reception signals are measured for each frame,

wherein when the reception levels of the reception signals in the current frame are lower than the predetermined threshold value, a correlation signal in the preceding frame is output from said inner memory, and

wherein said reception path timing generating portion selects a reception path from the preceding frame.

7. The mobile portable apparatus as set forth in claim 5, further comprising:

a plurality of finger circuits inversely spread the reception signals corresponding to the reception paths detected by said search engine portion and synchronously adds correlation output signals of said plurality of finger circuits.

8. The mobile portable apparatus as set forth in claim 6, further comprising:

a plurality of finger circuits inversely spread the reception signals corresponding to the reception paths detected by said search engine portion and synchronously adds correlation output signals of said plurality of finger circuits.

9. A base station apparatus of a cellular system using code divisional multiple access (CDMA) system, comprising:

an antenna for transmitting and receiving a signal to/from a mobile portable apparatus;

a radio portion for transmitting and receiving a signal to/from said antenna; and

a baseband portion for transmitting and receiving a signal to/from said radio portion,

wherein said baseband portion comprises;

a spreading portion for spreading a transmission digital signal,

a RAKE receiving portion for receiving signals corresponding to multi-paths, and

a search engine portion for detecting reception paths, wherein said search engine portion comprises;

a plurality of inversely spreading portions for multiplying reception signals by spread codes,

an inner memory for storing correlation signals received from said plurality of inversely spreading portions,

a reception level measuring portion for detecting reception levels from the reception signals, comparing the reception levels with a predetermined threshold value and outputting a compared result to said inner memory, and

a reception path timing generating portion for detecting reception paths from output signals of said inner memory and generating a path timing,

wherein said search engine portion determines whether or not to output a correlation signal of said inner memory to said reception path timing generating portion according to the compared result of said reception level measuring portion.

10. The base station apparatus as set forth in claim 9,

wherein the reception levels of the reception signals are measured for each frame,

wherein when the reception levels of the reception signals in the current frame are lower than the predetermined threshold value, a correlation signal in the preceding frame is output from said inner memory, and

wherein said reception path timing generating portion selects a reception path from the preceding frame.

11. The base station apparatus as set forth in claim 9, further comprising:

a plurality of finger circuits inversely spread the reception signals corresponding to the reception paths detected by said search engine portion and synchronously adds correlation output signals of said plurality of finger circuits.

12. An optimum path detecting method used for code divisional multiple access (CDMA) system for demodulating reception signals to baseband signals and causing a search engine portion to select reception paths corresponding to multi-paths from the baseband signals, comprising:

detecting reception levels of the baseband signals;

comparing the reception levels with a predetermined threshold value and outputting the compared results to an inner memory;

multiplying the baseband signals by a spread code so as to inversely spread the reception signals;

storing correlation signals corresponding to the inversely spread results to the inner memory;

detecting a reception path from an output signal of the inner memory;

generating a path timing corresponding to the reception path; and

selectively outputting the correlation signal from the inner memory corresponding to the compared results.

13. The optimum path detecting method as set forth in claim 12,

wherein the reception levels of the reception signals are measured for each frame, and

wherein when the reception levels of the reception signals in the current frame are lower than the predetermined threshold value, a correlation signal in the preceding frame is output from the inner memory and a reception path is elected from the preceding frame.

14. The optimum path detecting method as set forth in cm 12, further comprising the steps of:

inversely spreading the reception signals corresponding to the reception paths detected by the search engine portion; and

synchronously adding the correlation output signals.