Channel reuse in cellular mobile communication with interference signal levels of different radio channels measured at regular and shorter refresh intervals

Claim 2

A mobile communication system as claimed in claim 1, characterised in that said measuring means (23) does not further measure the interference signal level when said stored level is lower than a different reference level that is lower than said predetermined reference level.

Claim 3

A base station (13) for use in each cell (11) of a mobile communication system in transmitting a message to a mobile station (15) present in said cell through an allocated channel of a plurality of radio channels, said base station comprising measuring means (23) for measuring an interference signal level of each channel as a measured level, storing means (25) for storing said measured level as a stored level, and selecting means (27) for selecting said allocated channel based on said stored level, characterised in that said measuring means is for measuring the interference signal level of one of said radio channels during a first predetermined interval as said measured level and for further measuring the interference signal level of said one of radio channels during a second predetermined interval when said stored level is lower than a predetermined reference level.

Claim 4

A base station (13) as claimed in claim 3, characterised in that said measuring means (23) does not further measure the interference signal level when said stored level is lower than a different reference level that is lower than said predetermined reference level.

Claim 5

A base station (13) as claimed in claim 4, characterised in that said measuring means (23) comprises: calculating means (S12) for calculating a number ratio of first channels to said plurality of radio channels, each of said first channels having said measured level lower than said predetermined reference level; and adjusting means (S14, S16) for adjusting said predetermined reference level lower and higher when said number ratio is greater and smaller than a predetermined ratio and than a different ratio that is smaller than said predetermined ratio, respectively.

Claim 6

A mobile communication system comprising a base station (13) in each cell (11) for communication with a mobile station (15) in said cell through an allocated channel of a plurality of radio channels, said base station comprising measuring means (23) for measuring an interference signal level of each channel as a measured level, storing means (25) for storing said measured level as a stored level, and selecting means (27) for selecting said allocated channel based on said stored level, characterised in that said measuring means is for measuring said interference signal level at a refresh interval with said refresh interval given a short interval when said stored level is lower than a predetermined reference level.

Claim 7

A base station (13) for use in each cell (11) of a mobile communication system in transmitting a message to a mobile station (15) present in said cell through an allocated channel of a plurality of radio channels, said base station comprising measuring means (23) for measuring an interference signal level of each channel as a measured level, storing means (25) for storing said measured level as a stored level, and channel selecting means (27) for selecting said allocated channel based on said stored level, characterised in that said measuring means is for measuring said interference signal level at a refresh interval with said refresh interval given a short interval when said stored level is lower than a predetermined reference level.

Claim 8

A base station (13) as claimed in claim 7, characterised in that said measuring means (23) comprises: a first measuring unit (23(1)) for measuring said interference signal level at a first refresh interval to produce said measured level; a second measuring unit (23(2)) for measuring said interference signal level at a second refresh interval shorter than said first refresh interval to produce said measured level; and a unit selecting unit (21) for selecting said first and said second measuring units when said stored level is and is not lower than said predetermined reference level, respectively.

Claim 9

A base station (13) as claimed in claim 8, characterised in that said unit selecting unit (21) calculates a channel count of queued channels, each of which is in a queue for measurement by said first measuring unit (23(1)), and selects said second measuring unit (23(2)) regardless of a relation between said stored level and said predetermined reference level when said channel count is greater than a predetermined reference count.

Claim 10

A base station (13) as claimed in claim 8, characterised in that said unit selecting unit (21) selects said second measuring unit (23(2)) when said stored level is higher than said predetermined reference level regardless of a channel count of queued channels each of which is in a queue for measurement by said first measuring unit (23(1)).

Claim 11

A base station (13) as claimed in claim 8, characterised in that said unit selecting unit (21) repeatedly selects said first measuring unit (23(1)) when said stored level is not higher than said predetermined reference level and furthermore when a predetermined reference count is not exceeded by a channel count of quelled channels each of which is in a queue for measurement by said first measuring unit.

Claim 12

A base station (13) as claimed in claim 8, characterised in that said unit selecting unit (21) gives a lower and a higher reference level to said predetermined reference level so as to keep, in a predetermined range, a channel count of queued channels each of which is in a queue for measurement by said first measuring unit (23(1)).

Claim 13

A base station (13) as claimed in claim 7, characterised in that said measuring means (23) gives a lower and a higher reference level to said predetermined reference level when said interference signal level should be measured in said refresh and said short intervals, respectively.

Claim 14

A base station (13) as claimed in claim 7, characterised in that said channel selecting means (27) suspends operation of said measuring means (23) when said each channel is said allocated channel.

Claim 15

A mobile communication system comprising a central base station (29) and a plurality of microcell base stations (15) placed in respective microcells (11) and connected to said central base station through transmission paths (35), one microcell base station in each microcell being for communication with a mobile station (15) in said each microcell through an allocated channel of a plurality of radio channels, characterised in that said central base station comprises: regular measuring means (41) for measuring an interference signal level of each radio channel as a measured level at a regular refresh interval; storing means (47) for storing said measured level as a stored level; control means (45) for calculating, in connection with each microcell base station, a channel count of free channels for each of which said stored level is lower than a predetermined reference level; and additional measuring means (43) for measuring the interference signal level of each radio channel additionally as said measured level at a short refresh interval shorter than said regular refresh interval in connection with each less-count base station of said microcell base stations, the channel count of said less-count base station being less than a predetermined reference count; said control means selecting said allocated channel based on the stored level which includes the stored level stored in response to the measured level measured additionally by said additional measuring means.

Claim 16

A central base station (29) for use in a mobile communication system comprising a plurality of microcell base stations (13) placed in respective microcells (11) and connected to said central base station through transmission paths (35), one microcell base station in each microcell being for communication with a mobile station (15) in said each microcell through an allocated channel of a plurality of radio channels, characterised in that said central base station comprises: regular measuring means (41) for measuring an interference signal level of each radio channel as a measured level at a regular refresh interval; storing means (47) for storing said measured level as a stored level; control means (45) for calculating, in connection with said microcell base station, a channel count of free channels for each of which said stored level is lower than a predetermined reference level; and additional measuring means (43) for measuring the interference signal level of said radio channel additionally as said measured level at a short refresh interval shorter than said regular refresh interval in connection with each less-count base station of said microcell base stations, the channel count of said less-count base station being less than a predetermined reference count; said control means selecting said allocated channel based on the stored level which includes the stored level stored in response to the measured level measured additionally by said additional measuring means.

Claim 17

A mobile communication system comprising a central base station (29) and a plurality of microcell base stations (13) placed in respective microcells (11) and connected to said central base station through transmission paths (35), one microcell base station in each microcell being for communication with a mobile station (15) in said each microcell through an allocated channel of a plurality of radio channels, characterised in that said central base station comprises: regular measuring means (41) for measuring an interference signal level of each radio channel as a measured level at a regular refresh interval; storing means (47) for storing said measured level as a stored level; control means (45, 49) for calculating, in connection with each microcell base station, a channel count of free channels, for each of which said stored level is lower than a predetermined reference level, a traffic value of said radio channels, and a traffic ratio of said channel count to said traffic value; and additional measuring means (43) for measuring the interference signal level of each radio channel additionally as said measured level at a short refresh interval shorter than said regular refresh interval in connection with each less-ratio base station of said microcell base stations, the traffic ratio of said less-ratio base station being less than a predetermined reference ratio; said control means selecting said allocated channel based on the stored level which includes the stored level stored in response to the measured level measured additionally by said additional measuring means.

Claim 18

A central base station (29) for use in a mobile communication system comprising a plurality of microcell base stations (13) placed in respective microcells (11) and connected to said central base station through transmission paths (35), one microcell base station in each microcell being for communication with a mobile station (15) in said each microcell through an allocated channel of a plurality of radio channels, characterised in that said central base station comprises: regular measuring means (41) for measuring an interference signal level of each radio channel as a measured level at a regular refresh interval; storing means (47) for storing said measured level as a stored level; control means (45, 49) for calculating, in connection with each microcell base station, a channel count of free channels, for each of which said stored level is lower than a predetermined reference level, a traffic value of said radio channels, and a traffic ratio of said channel count to said traffic value; and additional measuring means (43) for measuring the interference signal level of each radio channel additionally as said measured level at a short refresh interval shorter than said regular refresh interval in connection with each less-ratio base station of said microcell base stations, the traffic ratio of said less-ratio base station being less than a predetermined reference ratio; said control means selecting said allocated channel based on the stored level which includes the stored level stored in response to the measured level measured additionally by said additional measuring means.

Claim 19

A central base station (29) as claimed in claim 18, characterised in that said control means (45, 49) comprises: a traffic monitor (49) for monitoring said transmission paths (67) to detect said traffic value; and a control unit (47) for calculating said channel count and said traffic ratio and for selecting said allocated channel.