CDMA communication with a propagation delay between a base and a mobile station taken into account

• US 5,617,410 A
• Filed: 03/15/1995
• Issued: 04/01/1997
• Est. Priority Date: 03/15/1994
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Matsumoto, Mariko
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): BLUM, RUSSELL
• Application Number:
  US08/404,503
• Time in Patent Office: 748 Days
• Field of Search: 370/18, 370/95.3, 370/100.1, 370/103, 370/104.1, 379/58, 379/59, 379/63, 455/51.1, 455/54.1, 455/33.1, 375/205, 375/200
• US Class Current: 370/342
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04W 56/0075 based on arrival time vs. expected arrival time

Abstract

In a CDMA communication network, each base station (BS) is made to establish synchronism between a downward transmission signal directed to a mobile station (MS) and an upward reception signal received from the mobile station by adjusting in the mobile station a mobile generated SS pattern into an adjusted SS pattern of producing an upward transmission signal for reception at the base station as the upward reception signal. In order to get the adjusted SS pattern, the base station inserts in the downward transmission signal an inserted signal representative of a propagation delay t(D) between the base and the mobile stations and a propagation delay increment t(d) while the mobile station is in a prelminary state of receiving the downward transmission signal as a downward reception signal first from the base station and is in a steady state, respectively. The signals may ba propagated through at least one communication satellite. Preferably, each mobile station comprises a delay circuit (53) for synchronizing the adjusted SS pattern with an adjusted time, which is equal to t(B)-t(D) and to t(B)-t(d) in the preliminary and the steady states, where t(B) represents a base station absolute time at which a base generated SS pattern is generated for downward transmission signals directed to mobile stations covered by the base station.

Claims

1. A code division multiple access communication method comprising the steps of generating at a base station a base generated spectrum spread pattern, modulating a base transmission signal by said base generated spectrum spread pattern into a downward transmission signal for reception at a mobile station as a downward reception signal, synchronizing said base generated spectrum spread pattern with an upward reception signal received from said mobile station to produce a base synchronized spectrum spread pattern, demodulating said upward reception signal by said base spectrum spread pattern into a base reception signal, generating at said mobile station a mobile generated spectrum spread pattern, modulating a mobile transmission signal by using said mobile generated spectrum spread pattern as an adjusted spectrum spread pattern into an upward transmission signal for reception at said base station as said upward reception signal, synchronizing said mobile generated spectrum spread pattern with said downward reception signal to produce a mobile synchronized spectrum spread pattern, and demodulating said downward reception signal by said mobile synchronized spectrum spread pattern into a mobile reception signal, wherein said code division multiple access communication method comprises the steps of:

detecting at said base station a base station delay datum between said base generated and synchronized spectrum spread patterns;

inserting said base station delay datum into said downward transmission signal as an inserted delay datum; and

adjusting at said mobile station said mobile generated spectrum spread pattern into said adjusted spectrum spread pattern in response to said inserted delay datum.

2. The code division multiple access communication method as claimed in claim 1, wherein said inserting step inserts said inserted datum into said downward transmission signal in a time division fashion.

3. The code division multiple access communication method as claimed in claim 2, wherein said adjusting step comprises the steps of:

detecting said inserted delay datum from said mobile reception signal as a detected delay datum;

storing said detected delay datum as a stored delay datum; and

adjusting said mobile generated spectrum spread pattern into said adjusted spectrum spread pattern in response to said stored delay datum.

4. The code division multiple access communication method as claimed in claim 1, said base generated spectrum spread pattern being generated in synchronism with a base station absolute time, wherein:

said base station receives said upward reception signal with a propagation delay increment dependent on an increment in a distance between said base and said mobile stations relative to a transmission timing of said upward transmission signal at said mobile station after said mobile station is put in a steady state of operation;

said detecting step detecting said propagation delay increment as said base station delay datum;

said inserting step inserting said propagation delay increment as said inserted delay datum;

said adjusting step producing said adjusted spectrum spread pattern at an adjusted time which is equal to said base station absolute time minus said propagation delay increment.

5. The code division multiple access communication method as claimed in claim 4, wherein:

said base station receives said upward reception signal with a propagation delay dependent on a distance between said base and said mobile stations relative to a transmission timing of said upward transmission signal at said mobile station while said mobile station is in a preliminary state after first receiving said downward reception signal and before being put in said steady state;

said detecting step detecting said propagation delay as said base station delay datum;

said inserting step inserting said propagation delay as said inserted delay datum;

said adjusting step producing said adjusted spectrum spread pattern at an adjusted time which is equal to said base station absolute time minus said propagation delay.

6. A base station which is for use in a code division multiple access communication network comprising a mobile station and which comprises a spectrum spread pattern generator for generating a base generated spectrum spread pattern, modulator means for modulating a base transmission signal by said base generated spectrum spread pattern into a downward transmission signal for reception at said mobile station as a downward reception signal, synchronizing means for synchronizing said base generated spectrum spread pattern with an upward transmission signal received from said mobile station as an upward reception signal to produce a base synchronized spectrum spread pattern, and demodulator means for demodulating said upward reception signal by said base synchronized spectrum spread pattern into a base receptions signal, wherein said base station further comprises:

detecting means for detecting a base station delay datum between said base generated and synchronized spectrum spread patterns and;

inserting means for inserting said base station delay datum into said downward transmission signal as an inserted delay datum to adjust, at said mobile station, a mobile generated spectrum spread pattern into an adjusted spectrum spread pattern in response to said inserted delay datum.

7. The base station as claimed in claim 6, wherein said inserting means inserts said base station delay datum into said downward transmission signal in a time division fashion.

8. The base station as claimed in claim 7, said demodulator means comprising a receiver unit for receiving said upward reception signal as an upward base station signal, a spectrum spread demodulator for demodulating said upward base station signal by said base synchronized spectrum spread pattern into a base spectrum spread signal, a demodulator unit for demodulating said base spectrum spread signal into a base demodulated signal, a switch supplied with said base demodulated signal, and detector means for detecting whether or not said base demodulated signal is directed to said base station, said detector means producing a switch control signal for making said switch produce said base demodulated signal as said base reception signal when said base demodulated signal is directed to said base station, wherein said detecting means comprises:

an encoder for encoding a supplied datum into an encoded signal; and

a central processing unit supplying said encoder with said base station delay datum as said supplied datum to deliver said encoded signal to said switch, said switch control signal making said switch insert said encoded signal into said downward transmission signal as said inserted datum.

9. The base station as claimed in claim 6, said spectrum spread pattern generator generating said base generated spectrum spread pattern in synchronism with a base station absolute time, wherein:

said base station receives said upward reception signal with a propagation delay increment dependent on an increment in a distance between said base and said mobile stations relative to a transmission timing of said upward transmission signal at said mobile station after said mobile station is put in a steady state of operation;

said detecting means detecting said propagation delay increment as said base station delay datum.

10. The base station as claimed in claim 9, wherein

said base station receives said upward reception signal with a propagation delay dependent on said distance relative to said transmission timing while said mobile station is put in a preliminary state after first receiving said downward transmission signal and before being put in said steady state;

said detecting means detecting said propagation delay as said base station delay datum.

11. A mobile station for use in a code division multiple access communication network comprising a base station comprising, in turn, a base station spectrum spread pattern generator for generating a base generated spectrum spread pattern, base station modulator means for modulating a base transmission signal by said base generated spectrum spread pattern into a downward transmission signal for reception at said mobile station as a downward reception signal, base station synchronizing means for synchronizing said base generated spectrum spread pattern with an upward reception signal received from said mobile station to produce a base synchronized spectrum spread pattern, and base station demodulator means for demodulating said upward reception signal by said base synchronized spectrum spread pattern into a base reception signal, and further comprising detecting means for detecting a base station delay datum between said base generated and synchronized spectrum spread patterns and inserting means for inserting said base station delay datum into said downward transmission signal as an inserted delay datum, and which comprises a mobile station spectrum spread pattern generator for generating a mobile generated spectrum spread pattern, mobile station modulator means for modulating a mobile transmission signal by said mobile generated spectrum spread pattern as an adjusted spectrum spread pattern into an upward transmission signal for reception at said base station as said upward reception signal, mobile station synchronizing means for synchronizing said mobile generated spectrum spread pattern with said downward reception signal to produce a mobile synchronized spectrum spread pattern, and mobile station demodulator means for demodulating said downward reception signal by said mobile synchronized spectrum spread pattern into a mobile reception signal, wherein said mobile station comprises adjusting means for adjusting said mobile generated spectrum spread pattern into said adjusted spectrum spread pattern in response to said inserted delay datum.

12. The mobile station as claimed in claim 11, wherein said inserted delay datum is inserted in said downward reception signal in a time division fashion.

13. The mobile station as claimed in claim 12, said mobile station comprising a demodulator unit for demodulating said downward reception signal by said mobile synchronized spectrum spread pattern into a mobile demodulated signal and mobile station detector means for judging whether or not said mobile demodulated signal is directed to said mobile station as said mobile reception signal, wherein said mobile station comprises:

a delay detector for detecting said inserted delay datum as a detected delay datum in said mobile reception signal; and

a delay circuit responsive to said detected delay datum for adjusting said mobile generated spectrum spread pattern into said adjusted spectrum spread pattern.

14. The mobile station as claimed in claim 11, said base station spectrum spread pattern generator generating said base generated spectrum spread pattern in synchronism with a base station absolute time, wherein:

said base station receives said upward reception signal with a propagation delay increment dependent on an increment in a distance between said base and said mobile stations relative to a transmission timing of said upward transmission signal at said mobile station after said mobile station is put in a steady state of operation;

said base station delay datum being equal to said propagation delay increment;

said adjusting means producing said adjusted spectrum spread pattern at an adjusted time which is equal to said base station absolute time minus said propagation delay increment.

15. The mobile station as claimed in claim 14, wherein:

said base station receives said upward reception signal with a propagation delay dependent on said distance relative to said transmission timing while said mobile station is put in a preliminary state after first receiving said downward reception signal, and before being put in said steady state;

said base station delay datum being equal to said propagation delay;

said adjusting means producing said adjusted spectrum spread pattern at an adjusted time which is equal to said base station absolute time minus said propagation delay.