Directivity control antenna apparatus for shaping the radiation pattern of antenna of base station in mobile communication system in accordance with estimated directions or positions of mobile stations with which communication is in progress

• US 6,188,913 B1
• Filed: 08/26/1997
• Issued: 02/13/2001
• Est. Priority Date: 08/28/1996
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Fukagawa, Takashi, Hasegawa, Makoto, Matsuoka, Akihiko, Adachi, Naoki
• Primary Examiner(s): Bost, Dwayne D.
• Assistant Examiner(s): Craver, Charles R
• Application Number:
  US08/917,596
• Time in Patent Office: 1,267 Days
• Field of Search: 455/562, 455/561, 455/507, 455/524, 455/525, 455/65, 455/67, 455/3, 455/447, 455/456, 455/448, 455/277.1, 342/359, 342/173, 342/174, 342/372, 342/373, 342/374, 342/375, 343/890, 343/891, 343/892
• US Class Current: 455/562.1
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/30 varying the relative phase between the radiating elements of an array H01Q3/2605, H01Q3/2658, H01Q3/2682, H01Q3/44 take precedence
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

In a mobile communication system, each base station is provided with an array antenna, a section for estimating the respective directions of one or more mobile stations with which the base station is in communication, based on estimated incoming directions of radio waves received from these mobile stations, and sections for operating on respective signals of the antenna elements constituting the array antenna such as to shape the radiation pattern of the antenna to form peaks of directivity which are oriented in the estimated directions of these mobile stations, and can include a capability for shaping these peaks in accordance with estimated positions of these mobile stations, thereby minimizing interference between transmissions from that base station and communication being executed between other adjacent stations of the system, and minimizing the number of different transmission frequencies required in the overall system.

Claims

1. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station,

wherein said incoming direction estimation means estimates said incoming direction of radio waves from said mobile station by utilizing a method that is based upon phase relationships and values of amplitude of said intermediate frequency signals or baseband signals respectively corresponding to individual ones of said antenna elements, and

wherein said antenna directivity control means comprises means responsive to said control signals from said peak generating means for controlling the phase and amplitude of respective received signals of said antenna elements and transmission signals of said antenna elements, which are at said intermediate frequency or said baseband frequency.

2. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station;

further comprising means for controlling said antenna directivity control means to establish a substantially uniform directivity of said antenna, wherein said incoming direction estimation means derives said estimated direction only while said condition of uniform directivity is established, and wherein said antenna directivity control means comprises means responsive to said control signals from said peak generating means for directly controlling the phase and amplitude of respective transmission signals and received signals of said antenna elements, which are at said transmission frequency.

3. In a mobile communication system having a base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising

a first array antenna having an array of antenna elements, for receiving radio waves from one or more mobile stations which are located within a predetermined service area of the base station,

a second array antenna having an array of antenna elements, for transmitting and receiving radio waves for communication with a selected one of said mobile stations,

frequency conversion means for converting respective received signals from said antenna elements of said first and second array antennas to corresponding intermediate frequency signals or corresponding baseband frequency signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals at a transmission frequency, respectively corresponding to said antenna elements of said second array antenna, and supplying said transmission signals to the corresponding antenna elements of said second array antenna during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals derived by said frequency converter means from said received signals of the antenna elements of said first array antenna to thereby estimate respective incoming directions of radio waves from said mobile stations which are within the service area, for generating direction data indicative of said estimated directions, and for utilizing said direction data to estimate a total number of said mobile stations which are within said service area,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements of the second array antenna during said receiving mode and of said transmission signals respectively corresponding to said antenna elements of the second array antenna during said transmission mode such as to determine a directivity of said second array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmission mode and said receiving mode, to control said antenna directivity control means such as to form a peak of directivity of the second array antenna, oriented in an estimated direction of said selected mobile station.

4. A directivity control antenna apparatus according to claim 3, further comprising

means for judging whether said number of mobile stations obtained as said estimate from said incoming direction estimation means is equal to or greater than the number of elements of said first array antenna,

means functioning, when said estimated number of mobile stations is judged to be equal to or greater than said number of elements of the first array antenna, for executing control whereby respective received signals obtained from all said elements of the first array antenna and all said elements of the second array antenna are used in combination by the incoming direction estimation means for estimating the incoming direction of radio waves from mobile stations, and are used to derive a corrected estimated number of said mobile stations which are within the service area of said base station.

5. A directivity control antenna apparatus according to claim 4, further comprising

means for judging whether said corrected estimated number of mobile stations within the service area is equal to or greater than the total number of elements of said first array antenna and said second array antenna,

means functioning, when said number of mobile stations obtained as said estimate is judged to be equal to or greater than said total number of elements, for controlling said peak generating means to generate said control signals during said receiving mode of the base station such that said antenna directivity control means controls the phase and amplitude of said respective received signals of said antenna elements to produce a single peak of said radiation pattern, and to sweep said peak through an entire range of directivity variation of said first array antenna, and

means, functioning during said peak sweeping to successively detect reception of transmitted radio waves from respective mobile stations which are within said service area, to thereby obtain respective detected directions of said mobile stations with respect to said base station;

wherein said base station successively executes communication with each of said mobile stations for which respective directions are thereby detected, during successive intervals in which said peak has been swept to said respective directions.

6. In a mobile communication system having a base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising

a linear array antenna, having elements thereof spaced along an array axis,

at least one offset antenna element, having directivity in a direction which is offset from said array axis of said array antenna by a fixed angle,

incoming direction estimation means for receiving respective received signals of said offset antenna element and of a set of elements of the array antenna as received signals of a first antenna element set and receiving respective received signals of remaining elements of the array antenna as received signals of a second antenna element set, during a receiving mode of operation of said base station, for combining the received signals of the elements of the first antenna set and combining the received signals of respective elements of the second antenna set to thereby obtain two combined received signals, for obtaining the magnitude of the difference between these combined received signals, for estimating the direction at which a mobile station is located, based on that difference between the magnitudes, and generating direction data indicative of said direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements of the array antenna during said receiving mode and of transmission signals respectively corresponding to said antenna elements during a transmission mode of operation of said base station, such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmission mode and said receiving mode, to control said antenna directivity control means such as to form a peak of directivity of said array antenna, oriented in said estimated direction.

7. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station,

wherein said mobile communication system includes a plurality of base stations and wherein said base stations are connected by communication lines for interchange of data, wherein each of said base stations has a fixed number of communication channels available thereto for communication with mobile stations, wherein each of said base stations further comprises means for deriving respective identification information for mobile stations which are within said service area of the base station, wherein said incoming direction estimation means utilizes said estimated incoming directions of radio waves from mobile stations to estimate a total number of said mobile stations which are currently located within said service area of said base station, wherein said incoming direction estimation means of each base station is further capable of deriving estimated direction data for mobile stations which are located within service areas which are outside said service area of said base station, and wherein each of said base stations further comprises

mobile station position estimating means for receiving said direction data from said incoming direction estimation means, and for utilizing said direction data to estimate respective positions of mobile stations and generate position data indicative of said positions, and

antenna directivity pattern selection means for receiving said estimated number of mobile stations from said incoming direction estimation means and said position data from said mobile station position estimating means, and for operating on said number of mobile stations and position data by

based on said estimated number of mobile stations and allocated number of communication channels, determining a number of communication channels which are currently available to said base station or a number of mobile stations for which no communication channels are available,

when it is found that that one or more communication channels are available, receive data from one or more other base stations specifying respective identification information for selected mobile stations which are located within service areas of said other base stations, obtain from said mobile station position estimating means respective position data for said selected mobile stations in addition to position data for the mobile stations which are located within the service area, and generate and supply to said antenna directivity control means control signals for controlling said antenna directivity control means to produce peaks of antenna directivity as required for communication by said base station with said mobile stations which are within the service area and with said selected mobile stations which are located within said service areas of the other base stations, and

when it is found from said judgement operation that there is an insufficient number of communication channels available, sending to other base stations identification information for selected mobile stations which are within the service area of said base station.

8. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station,

wherein each of said mobile stations further comprises control signal transmitting means, for executing radio transmission using randomly selected frequency channels in randomly determined fixed duration time slots which are selected from a fixed sequence of time slots, said frequency channels being selected from a number N of frequency channels where N is a fixed integer, wherein said incoming direction estimation means of said base station performs said direction estimation based on respective received signals from said antenna elements after conversion to an intermediate frequency by said frequency converter means, and

wherein said base station further comprises

a set of variable-frequency bandpass filters for respectively transferring said intermediate frequency signals of said antenna elements to said incoming direction estimation means, and

means for successively changing a passband of each of said variable-frequency filters in successive ones of N fixed-duration sub-intervals of each of said time slots, to enable said each variable-frequency filter to sequentially pass intermediate frequency values which corresponding to successive ones of said frequency channels, in successive ones of said sub-intervals, in each of said time slots.

9. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station,

wherein said incoming direction estimation means estimates said incoming direction of radio waves from said mobile station by utilizing a method that is based upon phase relationships and values of amplitude of said intermediate frequency signals or baseband signals respectively corresponding to individual ones of said antenna elements.

10. A directivity control antenna apparatus according to claim 9, further comprising means for detecting that a signal is being received from a mobile station which is within said service area, and wherein said incoming direction estimation means further comprises

means for deriving an estimated number of mobile stations which are currently located within said service area,

means for judging whether said estimated number of mobile stations within the service area is equal to or greater than the total number of elements of said array antenna, and

means functioning, when said number of mobile stations obtained as said estimate is judged to be equal to or greater than said total number of elements, for controlling said peak generating means to generate said control signals during said receiving mode of the base station such that said antenna directivity control means controls the phase and amplitude of said respective received signals of said antenna elements to produce a single peak of said directivity and to sweep said peak through an entire range of directivity variation of said array antenna;

whereby respective directions of mobile stations within said service area are obtained by said incoming direction estimation means as corresponding directions at which said detection of received signals occur, and wherein said base station successively executes communication with each of said mobile stations for which respective directions are thereby detected, during successive intervals in which said peak has been swept to said respective directions.

11. A directivity control antenna apparatus according to claim 9, wherein said mobile communication system comprises a plurality of base stations having respective service areas and mutually connected by communication lines for interchange of data, and wherein each said base station further comprises:

mobile station position estimation means for receiving from said incoming direction estimation means of said base station said direction for a mobile station and for receiving, from respective incoming direction estimation means of at least two other base stations, direction data for said mobile station with respect to said other base stations, for processing said data to obtain an estimated position of said mobile station and generating position data indicative of said estimated position, and supplying said position data to said peak generating means;

and wherein said peak generating means is responsive to said position data for generating control signals supplied to said antenna directivity control means for controlling said antenna directivity control means such as to determine both the orientation of a peak of said directivity and the shape of said peak, in accordance with said estimated position.

12. A directivity control antenna apparatus according to claim 9, wherein said mobile communication system comprises a plurality of base stations having respective mutually adjacent service areas and mutually connected for exchanging data expressing estimated directions of mobile stations, wherein each said array antenna of a base station is a linear array antenna having elements thereof spaced along an array axis, wherein each said base station further comprises:

mobile station position estimation means for receiving, from said incoming direction estimation means of said base station, first direction data indicative of the estimated incoming direction of radio waves received from a mobile station, for processing said direction data in conjunction with known data expressing a height of said array antenna above ground level to obtain first ground line data expressing a first range of possible positions of said mobile station, and for receiving, from respective incoming direction estimation means of at least two other base stations, second and third direction data indicative of respective incoming directions of radio waves from said mobile station with respect to said other base stations, for processing said second and third direction data to obtain second and third ground line data respectively indicative of a second and third ranges of possible positions of said mobile station, for deriving from said first, second and third ground line data an estimated position of said mobile station and generating position data indicative of said estimated position, and supplying said position data to said peak generating means;

and wherein said peak generating means is responsive to said position data for generating control signals supplied to said antenna directivity control means for controlling said antenna directivity control means such as to determine both the orientation of a peak of the directivity and the shape of said peak, in accordance with said estimated position.

13. A directivity control antenna apparatus according to claim 12, wherein each said linear array antenna is configured to provide azimuth directivity within a range of 180°

, and wherein each said range of possible positions of said mobile station is derived as an estimated line of intersection between said ground and one half of a conic surface having said array axis as a central axis thereof, said conic surface having an apex angle which is twice the value of an angle formed between said direction of incoming radio waves from said mobile station and said array axis.

14. A directivity control antenna apparatus according to claim 9, wherein said array antenna is a linear array antenna having elements thereof spaced along an array axis, further comprising

electric field strength measurement means for measuring a value of electric field strength of radio waves received from a mobile station, and

position estimation means for converting said combined signal strength value to a value of estimated line-of-sight distance of said mobile station from said array antenna, for operating on said estimated distance value in conjunction with a known value of height of said array antenna above ground to obtain ground line data expressing a range of possible positions of said mobile station, for operating on said ground line data in conjunction with said estimated direction data for said mobile station supplied from said incoming direction estimation means, to obtain position data expressing an estimated position of said mobile station with respect to said array antenna, and supplying said position data to said peak generating means;

wherein said peak generating means is responsive to said position data for generating control signals supplied to said antenna directivity control means for controlling said antenna directivity control means such as to determine both the orientation of a peak of said directivity and shape of said peak, in accordance with said estimated position.

15. A directivity control antenna apparatus according to claim 14, wherein each said linear array antenna is configured to provide azimuth directivity within a range of 180°

, and wherein each said range of possible positions of said mobile station is derived as an estimated line of intersection between said ground and one half of a conic surface, said conic surface having a central axis along said array axis and having an apex angle which is twice the value of angle formed between said direction of incoming radio waves from said mobile station and said array axis.

16. A directivity control antenna apparatus according to claim 9 wherein each said mobile station comprises

displacement vector generating means for deriving a displacement vector expressing a difference between a position of said mobile station at a first time point(t₁) and a position of said mobile station at a second time point (t₂) subsequent to said first time point, and

means for transmitting data expressing said displacement vector to said base station by radio;

and

wherein said wherein said array antenna of said base station is a linear array antenna having elements thereof spaced along an array axis, said base station further comprising mobile station position estimating means operating at said first time point (t₁) to operate on said estimated direction data for said mobile station, supplied from said incoming direction estimation means distance detection means, in conjunction with a known value of height of said array antenna above ground level, to derive first ground line data expressing a first range of possible positions of said mobile station, and operating at said second time point (t₂) to operate on said estimated direction data for said mobile station and said height value to derive second ground line data expressing a second range of possible positions of said mobile station, for operating on said displacement vector value in conjunction with said first ground line data and second ground line data to estimate the position of said mobile station at said second time point (t₁), for generating position data indicative of said estimated position and supplying said position data to said peak generating means;

wherein said peak generating means is responsive to said position data for generating control signals supplied to said antenna directivity control means for controlling said antenna directivity control means such as to determine both the orientation of a peak of said directivity and the shape of said peak, in accordance with said estimated position.

17. A directivity control antenna apparatus according to claim 16, wherein said linear array antenna is configured to provide azimuth directivity within a range of 180°

, and wherein each said range of possible positions of said mobile station is derived as an estimated line of intersection between said ground and one half of a conic surface, said conic surface having a central axis along said array axis and an apex angle which is twice the value of an angle formed between said direction of incoming radio waves from said mobile station and said array axis.

18. A directivity control antenna apparatus according to claim 9, wherein said wherein said array antenna of said base station is a linear array antenna having elements thereof spaced along an array axis, further comprising

antenna rotation means for rotating said array antenna with said array axis rotating within a horizontal plane, and

position estimation means for receiving said direction information, and for operating on at least first direction data from said incoming direction estimation means expressing a first estimated direction, derived when said array axis is at a first angular position, and second direction data expressing a second estimated direction, derived when said array axis has rotated to a second angular position, to estimate the position of said mobile station and generate position data indicative of said estimated position;

wherein said peak generating means is responsive to said position data for generating control signals supplied to said antenna directivity control means for controlling said antenna directivity control means such as to determine both the orientation of a peak of said directivity and the shape of said peak, in accordance with said estimated position.

19. A directivity control antenna apparatus according to claim 18, wherein said linear array antenna is configured to provide azimuth directivity within a range of 180°

, and wherein said position estimating means

operates on said first direction data in conjunction with a known value of height of said array antenna above ground level to derive a first range of possible positions of said mobile station as a first estimated line of intersection between said ground and one half of a conic surface, said conic surface having a central axis along said array axis and an apex angle which is twice the value of an angle formed between said direction of incoming radio waves from said mobile station and said array axis,

operates on said second direction data in conjunction with said height value to derive a second range of possible positions of said mobile station as a second estimated line of intersection between said conic surface and ground, and

obtains a point of intersection between said first and second estimated lines of intersection, as said position of said mobile station.

20. A directivity control antenna apparatus according to claim 9, further comprising

propagation delay time estimation means for estimating the propagation delay time of radio waves received from a mobile station,

electric field strength measurement means for measuring the respective strengths of electric fields of radio waves received as direct waves and radio waves received as reflected waves, from said mobile station, and

propagation path equalization means for receiving said incoming direction data from said incoming direction estimation means and an estimated value of propagation delay time from said propagation delay time estimation means, and functioning, when results of estimation of radio wave incoming direction by said incoming direction estimation means indicate that said mobile station is the only mobile station within said service area of said base station, to compensate a signal received from said mobile station for the effects of multi-path propagation signals, based on said estimated radio wave propagation delay time and a ratio of said electric field strengths of said direct waves and reflected waves.

21. A directivity control antenna apparatus according to claim 20, wherein said propagation path equalization means comprises a plurality of delay elements connected in cascade for applying successive increments of delay to said received signal, and means for combining respective output signals of said delay elements in proportions which are determined in accordance with said estimated radio wave propagation delay time and said ratio of electric field strengths of direct waves and reflected waves.

22. A directivity control antenna apparatus according to claim 9, further comprising

null point generating means functioning, when respective incoming radio wave directions have been estimated for N mobile stations by the incoming direction estimation means, to establish null points of the directivity of said array antenna, respectively oriented in the directions of(N−

1) of the mobile stations, where N is an integer which is greater than one.

23. A directivity control antenna apparatus according to claim 9, wherein said incoming direction estimation means estimates said incoming direction of radio waves from said mobile station by periodically operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode for a duration of a time interval in which at least a predetermined minimum number of data bits are successively conveyed by said intermediate frequency signals or baseband signals, to estimate said incoming direction of radio waves from said mobile station.

24. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station,

wherein, in said transmission mode of operation, said antenna directivity control means controls the phase and amplitude of said transmission signals corresponding to and respectively provided to said respective antenna elements by applying to each individual transmission signal input to said frequency conversion means for output to a respective one of said antenna elements a respective phase relationship and amplitude control value.

25. In a mobile communication system having at least one base station and a plurality of mobile stations, a directivity control antenna apparatus for said base station, comprising:

an array antenna having an array of antenna elements, for transmitting and receiving radio waves to and from a mobile station which is located within a predetermined service area of the base station,

frequency conversion means for converting respective received signals from said antenna elements to corresponding intermediate frequency signals or baseband signals during a receiving mode of operation of said base station, and for converting a transmission signal at the intermediate frequency or baseband frequency to transmission signals respectively corresponding to said antenna elements, at a transmission frequency, and supplying said transmission signals to said antenna elements during a transmission mode of operation of said base station,

incoming direction estimation means for operating on said intermediate frequency signals or baseband signals from said frequency converter means during said receiving mode to estimate an incoming direction of radio waves from said mobile station, to thereby derive an estimated direction of said mobile station with respect to said base station, and for generating direction data indicative of said estimated direction,

antenna directivity control means for controlling the phase and amplitude of said received signals corresponding to said antenna elements during said receiving mode and of said transmission signals respectively corresponding to said antenna elements during said transmission mode such as to determine a directivity of said array antenna, and

peak generating means responsive to said direction data for generating control signals during said transmitting mode and said receiving mode to control said antenna directivity control means such as to form a peak of said directivity, oriented in said estimated direction of said mobile station,

wherein in said receiving mode of operation, each of said respective antenna elements provides only a single received signal to said frequency conversion circuit, said frequency conversion circuit converting said received signals from each of said respective antenna elements into a plurality of intermediate frequency signals or baseband signals each respectively corresponding to only one of said received signals.