Digital mobile communications system and method for providing intensity/coverage reference maps using base stations and mobile stations

• US 5,423,067 A
• Filed: 09/04/1992
• Issued: 06/06/1995
• Est. Priority Date: 09/09/1991
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Manabe, Shinichi
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Pham, Chi H.
• Application Number:
  US07/940,994
• Time in Patent Office: 1,005 Days
• Field of Search: 455/33.1, 455/33.2, 455/33.4, 455/56.1, 455/51.1, 455/67.1, 455/67.7, 342/450, 342/457, 342/463, 342/464
• US Class Current: 455/524
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• 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 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A digital mobile communications system which maintains synchronization among sending data of base stations, measures the time delay of radio waves from mobile stations under control at the control base station and instructs the value of time delay to each mobile station to adjust the timing of sending data of mobile stations to establish synchronization of communications between the base station and the mobile stations, wherein the system comprises means for measuring at mobile stations relative time delays of radio waves from at least one base station other than the control base station with respect to the radio waves from the control base station and periodically reporting the relative time delays to the control base station, and means for calculating at the base station the distances between the mobile station and the base stations and further determining the current geographic positions of the mobile station.

Claims

1. A method of controlling a digital mobile communications system which maintains synchronization among data of base stations being sent, measures the time delay of radio waves transmitted from mobile stations under control at the control base station, instructs the value of said time delay to each of said mobile stations to adjust the timing of data of said mobile stations being sent to establish synchronization of communications between said base station and said mobile stations, measures at said mobile station relative time delays of radio waves transmitted from at least one base station other than said control base station with respect to the radio waves transmitted from said control base station, periodically reports the information on said relative time delays to said control base station from said mobile station, periodically calculates at said control base station the distances between said mobile station and each of said base stations based on said information on said time delay and relative time delays, and periodically determines at said control base station the current geographic position of said mobile station based on said calculated distances between said mobile station and each of at least three of said base stations by referring to geographic positional data of said base stations, said method comprising the steps of:

periodically measuring at said mobile station the electric field intensity of the radio waves transmitted from each of said base stations including said control base station during the same period as measuring said relative time delays,

reporting from said mobile station to said control base station information on said field intensity together with information on said relative time delays, and

depicting at an operation and maintenance center an electric field intensity distribution map for radio waves by plotting said electric field intensity of the same radio waves reported through said base stations from a plurality of said mobile stations at said current geographic positions of said mobile stations.

2. The method of controlling a digital mobile communications system according to claim 1, further comprising the step of depicting at said operation and maintenance center a map showing the coverage area of each of said base stations by plotting said current geographic positions of said mobile stations under control by assigning different designations to each base station for plotting.

3. A digital mobile communications system which maintains synchronization among data of base stations being sent, measures the time delay of radio waves transmitted from mobile stations under control at the control base station, instructs the value of said time delay to each of said mobile stations to adjust the timing of data of said mobile stations being sent to establish synchronization of communications between said base station and said mobile stations, measures at said mobile station relative time delays of radio waves transmitted from at least one base station other than said control base station with respect to the radio waves transmitted from said control base station, periodically reports information on said relative time delays to said control base station from said mobile station, periodically calculates at said control base station the distances between said mobile station and each of said base stations based on said information on said time delay and relative time delays, and periodically determines at said control base station the current geographic position of said mobile station based on said calculated distances between said mobile station and each of at least three of said base stations by referring to the geographic position data of said base stations, said system comprising:

means for periodically measuring at said mobile station the electric field intensity of radio waves transmitted from each of said base stations including said control base station during the same period as measuring said relative time delays,

means for reporting from said mobile station to said control base station information on said electric field intensity together with information on said relative time delays, and

means for depicting at an operation and maintenance center an electric field intensity distribution map for radio waves by plotting said electric field intensity of said radio waves reported through said base stations from a plurality of said mobile stations.

4. The digital mobile communications system according to claim 3, further comprising means for depicting a map showing the cover area of each of said base stations by plotting said current geographic positions of said mobile stations under control by assigning different designations to each base station for plotting.

5. A method for providing an electric field intensity distribution map for a digital mobile communications system comprising base stations having fixed geographical coordinate positions, said base stations including a control base station and a plurality of auxiliary base stations, said system further comprising a plurality of mobile stations under the control of said control base station, said method comprising the steps of:

(a) maintaining synchronization among data sent from said base stations;

(b) periodically measuring at said control base station time delays of radio waves transmitted from said mobile stations;

(c) periodically instructing said time delays to said mobile stations to adjust data sent from said mobile stations to establish synchronization of communications between said control base station and said mobile stations;

(d) periodically measuring at said mobile stations relative time delays of radio waves transmitted from said auxiliary base stations with respect to radio waves transmitted from said control base station;

(e) periodically measuring at said mobile stations an electric field intensity of the radio waves transmitted from said base stations;

(f) periodically reporting from said mobile stations said relative time delays and said electric field intensity measurements to said control base station;

(g) periodically calculating at said control base station the distance between said mobile stations and each of said base stations based on said time delay of said mobile stations and said relative time delays measured at said mobile stations;

(h) periodically determining at said control base station current geographical coordinate positions of said mobile stations based on said calculated distances between said mobile stations and each of at least three of said base stations by referring to said geographical coordinate positions of said base stations; and

(i) generating said electric field intensity distribution map for each of said base stations using said measurements of electric field intensity reported from said mobile stations and geographical coordinate positions of said mobile stations.

6. A method for providing a coverage area map for a digital mobile communications system comprising base stations having fixed geographical coordinate positions, said base stations including a control base station and a plurality of auxiliary base stations, said system further comprising a plurality of mobile stations under the control of said control base station, said method comprising the steps of:

(a) maintaining synchronization among data sent from said base stations;

(b) periodically measuring at said control base station time delays of radio waves transmitted from said mobile stations;

(c) periodically instructing said time delays to said mobile stations to adjust data sent from said mobile stations to establish synchronization of communications between said control base station and said mobile stations;

(d) periodically measuring at said mobile stations relative time delays of radio waves transmitted from said auxiliary base stations with respect to radio waves transmitted from said control base station;

(e) periodically reporting from said mobile stations said relative time delays to said control base station;

(f) periodically calculating at said control base station the distance between said mobile stations and each of said base stations based on said time delay of said mobile stations and said relative time delays measured at said mobile stations;

(g) periodically determining at said control base station current geographical coordinate positions of said mobile stations based on said calculated distances between said mobile stations and each of at least three of said base stations by referring to said geographical coordinate positions of said base stations;

(h) repeating steps (b) through (g) for a different control base station and a plurality of mobile stations under the control of said different control base station; and

(i) depicting said coverage area map by assigning different symbols to each of said control base stations and by plotting said symbols at geographical coordinate positions of said mobile stations under the control of said control base station corresponding to said symbol.

7. A digital mobile communications system for providing an electric field intensity distribution map comprising:

(a) base stations having fixed geographical coordinate positions, said base stations including a control base station and a plurality of auxiliary base stations;

(b) a plurality of mobile stations under the control of said control base station;

(c) means for maintaining synchronization among data sent from said base stations;

(d) means for periodically measuring at said control base station time delays of radio waves transmitted from said mobile stations;

(e) means for periodically instructing said time delays to said mobile stations to adjust data sent from said mobile stations to establish synchronization of communications between said control base station and said mobile stations;

(f) means for periodically measuring at said mobile stations relative time delays of radio waves transmitted from said auxiliary base stations with respect to radio waves transmitted from said control base station;

(g) means for periodically measuring at said mobile stations an electric field intensity of the radio waves transmitted from said base stations;

(h) means for periodically reporting from said mobile stations said relative time delays and said electric field intensity measurements to said control base station;

(i) means for periodically calculating at said control base station the distance between said mobile stations and each of said base stations based on said time delay of said mobile stations and said relative time delays measured at said mobile stations;

(j) means for periodically determining at said control base station current geographical coordinate positions of said mobile stations based on said calculated distances between said mobile stations and each of at least three of said base stations by referring to said geographical coordinate positions of said base stations; and

(k) means for generating said electric field intensity distribution map for each of said base stations using said measurements of electric field intensity reported from said mobile stations and geographical coordinate positions of said mobile stations.

8. A digital mobile communications system for providing a coverage area map comprising:

(a) base stations having fixed geographical coordinate positions;

(b) means for maintaining synchronization among data sent from said base stations;

(c) a first control base station and a plurality of first auxiliary base stations included in said base stations;

(d) a plurality of mobile stations under the control of said first control base station;

(e) means for periodically measuring at said first control base station time delays of radio waves transmitted from said mobile stations;

(f) means for periodically instructing said time delays to said mobile stations to adjust data sent from said mobile stations to establish synchronization of communications between said first control base station and said mobile stations;

(g) means for periodically measuring at said mobile stations relative time delays of radio waves transmitted from said first auxiliary base stations with respect to radio waves transmitted from said first control base station;

(h) means for periodically reporting from said mobile stations said relative time delays to said first control base station;

(i) means for periodically calculating at said first control base station the distance between said mobile stations and each of said base stations based on said time delay of said mobile stations and said relative time delays measured at said mobile stations;

(j) means for periodically determining at said first control base station current geographical coordinate positions of said mobile stations based on said calculated distances between said mobile stations and each of at least three of said base stations by referring to said geographical coordinate positions of said base stations;

(k) a second control base station and a plurality of second auxiliary base stations included in said base stations;

(l) a plurality of mobile stations under the control of said second control base station;

(m) means for periodically measuring at said second control base station time delays of radio waves transmitted from said mobile stations;

(n) means for periodically instructing said time delays to said mobile stations to adjust data sent from said mobile stations to establish synchronization of communications between said second control base station and said mobile stations;

(o) means for periodically measuring at said mobile stations relative time delays of radio waves transmitted from said second auxiliary base stations with respect to radio waves transmitted from said second control base station;

(p) means for periodically reporting from said mobile stations said relative time delays to said second control base station;

(q) means for periodically calculating at said second control base station the distance between said mobile stations and each of said base stations based on said time delay of said mobile stations and said relative time delays measured at said mobile stations;

(r) means for periodically determining at said second control base station current geographical coordinate positions of said mobile stations based on said calculated distances between said mobile stations and each of at least three of said base stations by referring to said geographical coordinate positions of said base stations; and

(s) means for depicting said coverage area map by assigning different symbols to each of said control base stations and by plotting said symbols at geographical coordinate positions of said mobile stations under the control of said control base station corresponding to said symbol.