EP0897225A2
Expired / Lapsed
EP
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Mobile station and method for transmission power control and interference reduction in mobile communication systems
Assignee: NEC Corp
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Filing: 1998-05-29
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Granted: —
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Expires: 2018-05-29
Abstract
Abstract In a method of controlling transmission power in a mobile station which switches a plurality of base stations from one to another with a hand-off time interposed on switching, an increase of the transmission power is suppressed with reference to reception levels of pilot signals sent from the plurality of the base stations which are divided into a first group of base stations under connection and a second group of base stations under non-connection. Specifically, the transmission power is slowly or gradually increased or kept constant when the reception level of the pilot signal sent from the second group base station exceeds that of the pilot signal sent from the first group base station.
Inventors
- 👤 Shousei Yoshida
- 👤 Akihisa Ushirokawa
- 👤 Hiroshi Furukawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 14:59
CPC Classifications
H; H04; H04W; H04W52/00; H04W52/04; H04W52/30; H04W52/36; H04W52/367; H04W52/362; H04W52/38; H04W52/40
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
220 words
A method of controlling transmission power in a mobile
station which is used in a CDMA cellular mobile radio communication
system, said CDMA cellular mobile radio communication system
comprising a plurality of base stations each of which transmits a pilot
signal pre-assigned to each base station and a control signal for power
control of the mobile station, said mobile station successively controlling
transmission power in response to the control signal sent from each of the
base stations during communication with the base stations, comprising the
steps of: periodically detecting, in the mobile station, a level of each pilot
signal sent from the plurality of the base stations; checking out whether or not the mobile station is being connected
to the plurality of the base stations; discriminating between a first group of the base stations under
connection and a second group of the base stations under non-connection; comparing a first reception level of the pilot signals concerned
with the first group of the base stations with a second reception level of
the pilot signals concerned with the second group of the base stations to
determine whether or not the first reception level is higher than the second
reception level; and suppressing an increase of the transmission power in the mobile
station when the second reception level exceeds the first reception level.
Claim 2
Independent Claim
200 words
A method of controlling transmission power in a CDMA
cellular mobile radio communication system which comprises a plurality
of base stations each of which transmits a pilot signal pre-assigned to each
base station and a plurality of mobile stations communicable with the base
stations, each of the mobile stations comprising first transmission power
control means for adjusting the transmission power on the basis of a
reception level concerned with the pilot signals and second transmission
power control means for controlling the transmission power by a control
step size on the basis of a control instruction sent from the base stations
under connection, comprising the steps of: receiving the pilot signals from the plurality of the base stations; determining the transmission power in inverse proportion to a
maximum one of reception levels of the pilot signals; judging whether or not a first reception level of the pilot signals
concerned with the base stations under connection exceeds a second
reception level of the pilot signals concerned with the base stations under
non-connection to produce a result of judgement; and changing the control step size from one to another when the second
reception level exceeds or does not exceed the first reception level.
Claim 3
Dependent Claim
48 words
A method as claimed in claim 2, wherein the changing step
comprises the steps of: decreasing the control step size when the second reception level
exceeds the first reception level; and increasing the control step size when the second reception level
does not exceed the first reception level.
Claim 4
Dependent Claim
74 words
A method as claimed in claim 2 or 3, wherein the changing step
comprises the steps of: rendering the control step size into a small step size for an increase
of the transmission power when the second reception level exceeds the
first reception level; and rendering the control step size into a large step size for a decrease
of the transmission power when the second reception level does not
exceed the first reception level.
Claim 5
Independent Claim
239 words
A method of controlling transmission power in a CDMA
cellular mobile radio communication system which comprises a plurality
of base stations each of which transmits a pilot signal pre-assigned to each
base station and a plurality of mobile stations communicable with the base
stations, each of the mobile stations comprising first transmission power
control means for adjusting the transmission power on the basis of a
reception level concerned with the pilot signals and second transmission
power control means for controlling the transmission power by a control
step size on the basis of a control instruction sent from the base stations
under connection, comprising the steps of: receiving the pilot signals from the plurality of the base stations; determining the transmission power in inverse proportion to a
maximum one of reception levels of the pilot signals; judging whether or not a first reception level of the pilot signals
concerned with the base stations under connection exceeds a second
reception level of the pilot signals concerned with the base stations under
non-connection to produce a result of judgement; minimizing the transmission power at every time interval for a
predetermined time period when the second reception level exceeds the
first reception level; and executing a control operation by the use of the first and the second
transmission power control means either during a time period except the
predetermined period or when the second reception level does not exceed
the first reception level.
Claim 6
Independent Claim
244 words
A method of controlling transmission power in a CDMA cellular
mobile radio communication system which comprises a plurality of base
stations each of which transmits a pilot signal pre-assigned to each base
station and a plurality of mobile stations communicable with the base
stations, each of the mobile stations comprising first transmission power
control means for adjusting the transmission power on the basis of a
reception level concerned with the pilot signals and second transmission
power control means for controlling the transmission power by a control
step size on the basis of a control instruction sent from the base stations
under connection, comprising the steps of: receiving the pilot signals from the plurality of the base stations; determining the transmission power in inverse proportion to a
maximum one of reception levels of the pilot signals; judging whether or not a first reception level of the pilot signals
concerned with the base stations under connection exceeds a second
reception level of the pilot signals concerned with the base stations under
non-connection to produce a result of judgement; decreasing the transmission power in the mobile station by a
predetermined amount at every preselected time interval when the second
reception level of the pilot signals exceeds the first reception level; and executing a control operation by the use of the first and the second
transmission power control means either during the preselected time
interval or when the second reception level does not exceed the first
reception level.
Claim 7
Independent Claim
40 words
A method as claimed in any one of claims 2 to 6, wherein the transmission
power in the first transmission power control means is determined in
inverse proportion to a reception level concerned with a whole of the pilot
signals.
Claim 8
Independent Claim
117 words
A method of controlling transmission power in a mobile
station in a CDMA cellular mobile radio communication system,
comprising the steps of: detecting each pilot signal level from a plurality of base stations; checking out whether or not the base stations are under connection
to discriminate between a first group of the base stations under connection
and a second group of the base stations under non-connection; and reducing the transmission power in the mobile station to suppress
an increase of the transmission power in the mobile station when a first
reception level concerned with the first group of the base stations does not
exceed a second reception level concerned with the second group of the
base stations.
Claim 9
Independent Claim
24 words
A method as claimed in any one of claims 1 to 8, wherein the detecting step
is periodically carried out in the mobile station.
Claim 10
Independent Claim
72 words
A method of controlling transmission power in a mobile
station in a radio communication system which comprise a plurality of
base stations, the mobile station being continuously communicable
through radio channels with the base stations by executing a hand-off
operation during a hand-off time, comprising the steps of: determining the hand-off time; and lowering the transmission power in the mobile station during the
hand-off time to mitigate interference among the radio channels.
Claim 11
Dependent Claim
53 words
A method as claimed in claim 10, wherein the hand-off time
detecting step comprises the steps of: receiving a plurality of constant power signals each of which is sent
from each base station at a predetermined power level; and determining the hand-off time with reference to each reception level
of the pilot signals.
Claim 12
Dependent Claim
25 words
A method as claimed in claim 11, wherein each of said
constant power signals is specified by a pilot signal sent from each base
station.
Claim 13
Dependent Claim
90 words
A method as claimed in claim 11 or 12, wherein the determining
step comprises the steps of: classifying the base stations into a first group base station under
connection and a second group base station under non-connection; comparing a first reception level concerned with the first group base
station with a second reception level concerned with the second group
base station to judge whether or not the second reception level exceeds the
first reception level; and deciding the hand-off time when the second reception level exceeds
the first reception level.
Claim 14
Dependent Claim
21 words
A method as claimed in claim 10, 11, 12 or 13, wherein the radio
channels are defined by a common frequency.
Claim 15
Independent Claim
34 words
A method as claimed in any one of claims 1-14, wherein each of the first
and the second reception levels is determined by a weighted sum of the
reception levels of the pilot signals.
Claim 16
Dependent Claim
67 words
A mobile station for use in a communication system which
comprise a plurality of base stations, the mobile station being continuously
communicable through radio channels with the base stations by executing
a hand-off operation during a hand-off time, comprising: means for determining the hand-off time; and means for lowering the transmission power in the mobile station
during the hand-off time to mitigate interference among the radio
channels.
References Cited (Backward Citations)
No citation records indexed.
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