JPH11122167A - Transmission power control method and system therefor in code division and multiplex cellular moving radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the interference of an incoming line by means of the sudden improvement of a transmission loss between a non-connection base station and a mobile station owing to the movement of the mobile station by reducing the transmission power of the mobile station, based on the weighting sum of pilot signal reception levels and suppressing the power increase of transmission power control. SOLUTION: When the reception level of a pilot signal in the non-connection base station B suddenly exceeds that of the connection base station A, a first transmission power control part FST suddenly reduces the output of the mobile station. The weighting sum of the reception level of the pilot signal in the connection base station is set to be Pac and that of the non-connection base station to be Pau. When Pau<Pac, a second transmission power control part SND sets a transmission power control step size to be ΔPL and the control step size to be ΔPS(<ΔPL) when Pau>Pac. During a connection processing with the base station B, ΔPS is set as the control step size, and the rise speed of transmission power becomes slow and excessive transmission power is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio communication system, and more particularly, to a mobile station used in a code division multiplexing cellular mobile radio communication system, and a transmission power control method in the mobile station.

[0002]

2. Description of the Related Art In general, this type of code division multiplexing cellular mobile radio communication system has an advantage that a plurality of base stations can use a common frequency and can effectively use the frequency. Attracting attention. That is,
In a code division multiplexing cellular mobile radio communication system, a plurality of radio base stations are spatially dispersed and arranged, and these base stations simultaneously communicate with the mobile station using the same frequency.

[0003] In this case, each mobile station is always connected to the base station having the minimum propagation loss and performs transmission power control, thereby performing communication with the base station at the required minimum transmission power. As a result, interference with other wireless channels is minimized, and simultaneous communication with more mobile stations is possible.

[0004] Here, each mobile station passing through the service area of a plurality of base stations moves while switching base stations sequentially. The operation of switching the base station in the mobile station as described above is usually called a handoff operation, and a period during which the handoff operation is performed is called a handoff period.

On the other hand, the service areas of the respective base stations are not always completely geometrically separated but usually overlap each other at the boundary.

In the case of a code division multiplexing cellular mobile radio communication system, in the overlapped portion, a plurality of base stations are communicated at the same time, and the necessity of a handoff operation is determined based on the result of the communication. , A soft handoff operation is performed in each mobile station.

As described above, in a code division multiplexing cellular mobile radio communication system, it is required to always minimize the transmission power of each mobile station during communication. This is because if there is at least one mobile station having excessively large transmission power, the same frequency is used, so that large interference occurs in other radio lines.

Therefore, it is necessary for a mobile station used in a code division multiplex cellular mobile radio communication system to control transmission power quickly and accurately.

However, according to the findings of the present inventors, it has been found that in the transmission power control that has been conventionally used, interference occurs inevitably during the soft handoff time.

Here, a transmission power control method conventionally used in mobile stations will be described.

A conventional transmission power control method in a mobile station includes a first transmission power control (so-called open loop type control) in which each base station determines an output by referring to a reception level of a pilot signal emitted from each base station. The second base station includes a second transmission power control (so-called closed loop control) for instructing the mobile station to perform transmission output so that the communication quality or the desired signal reception level of the base station becomes constant.

The first transmission power control is characterized by high-speed control that follows a sudden change in propagation loss because the transmission power can be adjusted immediately from the pilot signal reception level measured by the mobile station. On the other hand, the second transmission power control is characterized by accurate control for following a fluctuation of a desired signal due to fading and guaranteeing a constant quality or a constant reception level of the desired signal.

Hereinafter, a conventional transmission power control method will be described more specifically with reference to FIGS. 8, 9 and 10. FIG. 8 and 9 are block diagrams of portions related to transmission power control in the base station device and the mobile station device, respectively. First, the configuration and processing in the base station will be described with reference to FIG.
1 is received. The received signal from the mobile station is transmitted to the desired signal level measuring device 203 via the RF unit 202.
The received signal level is measured by the desired signal level measuring device 203.

The measured reception level is compared with a desired value of a desired signal level in a comparator 204. If the former exceeds the latter, the transmission power control bit is set to 0, and if not, the transmission power control bit is changed. Let it be 1. Here, when the value of the transmission power control bit is 1, it means an instruction to increase the transmission power of the connected mobile station, and when it is 0, it means an instruction to decrease.

In the code division multiplexing cellular mobile radio communication system, as described above, since a plurality of base stations perform a soft handoff operation for transmission and reception with respect to one mobile station, the transmission power control of the base station performing the soft handoff is performed. Each bit must be received at the mobile station. For this reason, the transmission power control bit is inserted in the transmission power control bit insertion section 207 into a symbol position unique to each base station for each slot of the transmission signal 208. The transmission signal including the transmission power control bits is spread in spreader 210 by a spreading code unique to the base station. Only the transmission power control bits from the connected base station are received at the mobile station.

On the other hand, the pilot signal is spread using the same spreading code in all base stations, and becomes a pilot spread signal 209 in which only the time offset is made different for each base station. The spread transmission signal including the transmission power control bit and the spread pilot signal are added in the adder 211, and are emitted to the mobile station by the duplexer 201 via the modulator 212 and the amplifier 213. The transmission power of the spread pilot signal is usually higher than the transmission signals of the other spread transmission signals, so that the mobile station also receives a spread pilot signal from a base station that is not actually communicating with the mobile station.

In consideration of this, a base station that can receive a spread pilot signal is actually communicating with a mobile station, that is, a connected base station (hereinafter, a connected base station or The first group base station) does not actually communicate, that is, is not connected to a base station (hereinafter, a non-connected base station or a second group base station). And can be divided into

Next, the mobile station apparatus will be described with reference to FIG.
In the mobile station, the transmission spread RF signal 101 is amplified by two variable output amplifiers 102 and 103, and emitted to the base station through the transmission / reception sharing device 104. The variable output amplifiers 102 and 103 are a first transmission power control amplifier and a second transmission power control amplifier, respectively.
The outputs of both variable output amplifiers 102 and 103 are the reception levels P _{I1 to} P _IN of the pilot signals from each base station included in the reception signal received by the mobile station, and the transmission power from the connected base station group. Control bits Bpc1 to BpcM
, And is controlled by the transmission power control unit CTL. Here, M represents the number of connected base stations, and N represents the number of base stations capable of receiving a spread pilot signal.

The mobile station reception signal is transmitted to the transmission / reception sharing device 104,
The signal is converted into a baseband signal via the RF unit 105 and the down converter 106. Transmission power control bit B
pc1 to BpcM convert baseband signals into despreaders ds
0, detected after passing through the received data demodulator dc0 and the transmission power control bit detector bd0.

The pilot signal reception levels P _{I1 to} P _IN are as follows:
After passing the baseband signal through a matched filter mf0 matched to the spreading code of the pilot signal, the signal is measured by a pilot level measuring device ld0 via a path detector pd0.

Here, an example of a processing flow in the transmission power control unit CTL of the mobile station in the conventional transmission power control method will be described with reference to FIG. In step S31, the maximum reception level among the pilot signal reception levels P _{I1 to} P _IN is detected, and the value Pm is set. Next, in step S32, the transmission power Popn for the first transmission power control is determined by the following equation so that the reception level of the desired wave at the base station becomes D1.

Popn = (Pt / Pm) × D1 (1) Here, Pt is the transmission power of the pilot signal emitted by each base station, and is assumed to be the same for all base stations. Pm / Pt represents the propagation loss from the base station to the mobile station.

Next, in step S33, the open-loop transmission power Popn is compared with the maximum transmit power control maximum transmission power Pomax that can be transmitted, and Popn is determined to be Pomax.
Is exceeded, Popn = P in step S34.
omax. Further, in step S35, P
opn and transmittable first transmit power control minimum transmit power P
omin is compared, and if Popn is less than Pomin, in step S36, Popn = Pomin
And

That is, in the first transmission power control, the open-loop transmission power Popn is set to the maximum value Pomax and the minimum value Pom.
Restrict to fall within the range of in.

Next, in step S37, it is determined whether or not all the transmission power control bits Bpc1 to BpcM from the connected base station are "1". If all are 1, in step S39, the transmission power Pcld by the second transmission power control is increased by the second transmission power control step size ΔP _F , otherwise, it is reduced by ΔP _F.

Next, in step S40, the second transmission power Pcld is compared with the transmittable second transmission power control maximum transmission power Pcmax, and Pcld is set to Pcmax.
If Pcld = Pcld = Pcld
Pcmax. Further, in step S42,
Pcld is compared with the transmittable second transmission power control minimum transmission power Pcmin. If Pcld is lower than Pcmin, in step S43, Pcld = Pcmi.
n. That is, the closed loop transmission power Pcld is limited so as to fall within the range between the maximum value Pcmax and the minimum value Pcmin.

[0027]

As shown in FIG. 7, a mobile station MS01 connected to a base station BS # A moves along a street R1 and suddenly sees a good area A01 from behind a building B01. , The propagation loss to the base station BS # B that has not been connected may be smaller than the propagation loss to the base station BS # A. Since the reception level of the pilot signal of each base station measured by mobile station MS01 is inversely proportional to the magnitude of the propagation loss, mobile station MS01 located in area A01 has the pilot signal reception level of base station BS # B of base station BS # B. Measured larger than that of #A.
In this case, the transmission power is immediately reduced by the first transmission power control in which the transmission power is determined according to the maximum pilot signal reception level. At the same time, connection processing with the base station BS # B having the minimum propagation loss is started.

The transition of the transmission power of the mobile station MS01 at this time will be described with reference to FIG.
Since the pilot signal reception level of the base station BS # B received by the mobile station MS01 suddenly becomes higher than that of the base station BS # A, the mobile station MS01 immediately reduces the transmission power by the first transmission power control. At the same time, base station BS #
A connection process with the base station BS # B is started while maintaining the connection with A. The connection process with the base station BS # B requires time Dh, during which time the transmission power starts to increase again based on a transmission power control command from the base station BS # A maintaining the connection. At time T2, when connection processing with base station BS # B is completed, transmission power control based on a command from base station BS # B is started, so that transmission power decreases in accordance with base station BS # B. Can be Here, the above-mentioned time Dh is called a handoff time.

As described above, despite the fact that the transmission power is reduced in accordance with the base station BS # B having the minimum propagation loss at the time T1, the connection time Dh with the base station BS # B causes the base station BS # B. Communication with excessive transmission power corresponding to A is forced. That is, the time D required for the base station connection process
During the time h, interference occurs to the base station BS # B, which is a problem. In a code division multiplexing cellular mobile radio communication system in which the same frequency is occupied by a plurality of mobile stations simultaneously, a plurality of mobile stations are interfered by an excessive transmission power of only one mobile station.

An object of the present invention is to provide a mobile station transmission power control method for suppressing uplink interference due to a rapid improvement in propagation loss between a non-connected base station and the mobile station due to the movement of the mobile station. It is to be.

Another object of the present invention is to provide a mobile station transmission power control method capable of reducing the transmission power of a mobile station during a handoff operation.

Still another object of the present invention is to provide an effective mobile station transmission power control method applied to a code division multiplexing cellular mobile radio communication system.

It is another object of the present invention to provide a mobile station capable of suppressing interference during a handoff operation.

[0034]

According to the transmission power control method of the present invention, the weighted sum of pilot signal reception levels of non-connected base stations exceeds the pilot signal reception level weighted sum of connected base stations. In this case, it is characterized in that the transmission power of the mobile station is reduced and, at the same time, the power increase of the transmission power control is suppressed.

In the premise of the code division multiplex cellular system, when the reception level of the pilot signal of the non-connected base station approaches that of the connected base station, connection processing with these non-connected base stations is started. . According to the method of the present invention, during the period until the connection process with the unconnected base station is completed, excessive transmission power of the mobile station imposed by the transmission power control with the currently connected base station is suppressed. As a result, interference given to non-connected base stations can be suppressed.

Further, according to the present invention, a handoff period,
A mobile station and a transmission power control method in the mobile station that perform a power suppression step of reducing transmission power of the mobile station and reducing interference between wireless channels are obtained.

[0037]

FIG. 1 shows a mobile station according to the present invention.
The configuration is the same as that of the conventional mobile station shown in FIG. 9, and the transmission power control method in the transmission power control unit CTL is different from that of the conventional mobile station. FIG. 1 shows a control flow diagram illustrating a first embodiment of the present invention,
Dotted frames FST and SND represent portions for performing the first transmission power control and the second transmission power control, respectively.

In step S01, among the pilot signal reception levels P _{I1 to} P _IN , the maximum reception level is Pm,
Let Pac be the weighted sum of the pilot signal reception levels of the connected base stations and Pau be the weighted sum of the pilot signal reception levels of the non-connected base stations. It should be noted that both the connected base station and the non-connected base station may be singular or plural. The weighted sum Pac of the pilot signal reception levels of the connected base stations and the weighted sum Pau of the pilot signal reception levels of the non-connected base stations are obtained by the following equation (1).

[0039]

(Equation 1)

Here, k _i is a weighting factor for base station #i, and P _li is a pilot signal reception level from base station #i. The k _i, when setting all of the coefficients to 1, there is a case of setting the k _i = Pli. Furthermore, c
m is the number of the base station with the largest Pli among the base stations with fc (i) = 1, and um is the number of the base station with the largest Pli among the base stations with fc (i) = 0. K _cm = 1, k _um = 1, k _i = 0 (where i is cm
And um. ) May be set.

In step S02, the transmission power Popn for the first transmission power control is determined by the above equation (1) so that the reception level of the desired wave at the base station becomes D1. In step S03, the first transmission power Popn is compared with the first transmittable maximum transmission power Pomax, and if Popn exceeds Pomax, Popn = Pomax is set in step S04. Further, in step S05, Popn is compared with the first transmit power control minimum transmit power Pomin that can be transmitted.
If opn is less than Pomin, step S06
Is set to Popn = Pomin.

Next, in step S07, the following equation (2)
It is determined whether or not the condition is satisfied.
The transmission power control step size and [Delta] P _L at 8,
The transmission power control step size and [Delta] P _S in step S09 satisfies. Here, ΔP _S is set smaller than ΔP _L.

Pau> Pac (2) The case where equation (2) is satisfied, that is, the weighted sum of the pilot signal reception levels of the non-connected base stations is equal to the pilot signal reception level of the connected base station. This is the case where the weighted sum is exceeded.

Next, in step S10, it is determined whether or not the transmission power control bits Bpc1 to BpcM from the connected base station are all "1". If everything is 1,
In step S12, the second transmission power control transmission power Pcld is increased by the second transmission power control transmission power control amount ΔP.
Reduce ld by ΔP. At this time, as P, Pau>
If Pac, ΔP _S is used, and if Pau <Pac, ΔP _L is used.

Next, in step S13, the second transmission power control transmission power Pcld is compared with the transmittable maximum second transmission power control transmission power. If Pcld exceeds Pcmax, in step S14, Pcld = Pcld
cmax. Further, in step S15, P
cld and transmittable second transmit power control minimum transmit power P
When Pcld is smaller than Pcmin, in step S16, Pcld = Pcmin
And

FIG. 6 shows a time transition of the transmission power of the mobile station when the embodiment of the present invention is applied to the situation shown in FIG. That is, at time T1, the pilot signal reception level of base station BS # B becomes base station BS # B.
If the output power of the mobile station MS01 suddenly exceeds that of #A, the output of the mobile station MS01 is rapidly reduced by the first transmission power control. at the same time,
The connection process with the base station BS # B is started, and thereafter, after a connection process time, that is, a handoff time Dh, a time T2
Starts communication with the base station BS # B.

As shown in FIG. 6, in the case of the present invention, during the connection processing time Dh, the control step size ΔP is set to ΔP
_S is set, but since ΔP _S is set small, the rate of increase of the transmission power becomes slow. As a result, excessive transmission power is suppressed, and the minimum propagation loss base station BS # during connection processing is set. The interference with B can be kept small.

In other words, according to the present invention, it can be seen that by reducing the transmission power of the mobile station during the handoff period Dh, interference with other radio channels is reduced. That is, since the handoff period Dh is performed within a predetermined time, the transmission power may be reduced during this period.

In the second transmission power control section SND of FIG. 1, the transmission power control step size is set small regardless of the increase or decrease of the transmission power. However, from the viewpoint of suppressing excessive transmission power, the control is performed only when the power is increased. The step size can be set small.

FIG. 2 shows the second transmission power control unit S in that case.
It is a control flow which shows 2nd Embodiment of ND. That is, in step S50, it is determined whether or not Expression (2) is satisfied. If not, the transmission power control step size ΔP + is set to the control step size ΔP _L in step S51, and if so, the transmission power control step size ΔP + is set in step S52. Control step size ΔP _{S +}
And Here, ΔP _{S +} is set smaller than ΔP shown in FIG. If the control step size ΔP _{S + is set} to 0 dB, an increase in the transmission power of the mobile station can be prohibited during that time.

Next, in step S53, it is determined whether or not all the transmission power control bits Bpc1 to BpcM from the connected base station are 1. If everything is 1,
In step S55, the closed-loop transmission power Pcld is increased by the closed-loop transmission power control amount ΔP +, otherwise, in step S54, Pcld is decreased by ΔP.

In FIGS. 1 and 2, the control step size is variable in order to suppress the increase or decrease in the transmission power control. However, the average transmission power may be suppressed by fixing the control step size and setting the output of the mobile station to the minimum output for a certain period at regular time intervals.
FIG. 3 is a control flow showing the third embodiment below the second transmission power control unit SND in that case.

That is, in step S60, the transmission power control bits Bpc1 to Bpc from the connected base station are
It is determined whether or not M is all ones. If all are 1, in step S62, the transmission power Pcld 'for the second transmission power control is increased by ΔP, and otherwise, Pcld' is reduced by ΔP in step S61.

Next, in step S63, equation (2)
It is determined whether or not the condition is satisfied. If not, the process proceeds to step S6.
In 6, the closed-loop transmission power Pcld is set to Pcld '.

If equation (2) is satisfied, step S64
In step S65, it is determined whether or not the following equation (3) holds. If so, in step S65, Popn, Pcld
Are Pomin and Pcmin, respectively, and if not, in step S66, the closed-loop transmission power P
cld is P ′.

{(T / Tm) −int (t / Tm)} × Tm <k × Tm (3) where t is an absolute time in units of a transmission power control cycle,
Tm is a second transmission power reduction period defined by a time in units of a transmission power control period, and k (= 0 to 1) represents a second transmission power reduction period given as a ratio to Tm.

Next, in step S67, the second transmission power control transmission power Pcld 'is compared with the transmittable second transmission power control maximum transmission power Pcmax', and Pcld '
Is greater than Pcmax in step S68.
cld '= Pcmax. Further, step S69
, Pcld ′ is compared with the transmittable second transmission power control minimum transmission power Pcmin, and Pcld ′ is Pcmd.
If it is less than in, Pcl is determined in step S70.
Let d '= Pcmin.

Also, the transmission step size of the second transmission power control is fixed, and the transmission power of the mobile station is reduced by a predetermined amount at regular time intervals, whereby interference to the minimum propagation loss base station can be suppressed. FIG. 4 is a control flow showing a fourth embodiment of the second transmission power control unit SND in that case. That is, in step S71, the transmission power control bits Bpc1 to Bp
It is determined whether or not cM is all ones. If all are 1, the second transmission power control transmission power Pcld is increased by ΔP in step S73, and otherwise, Pcld is decreased by ΔP in step S72.

Next, in step S74, equation (2)
It is determined whether or not the condition is satisfied.
Proceed to 3. If equation (2) is satisfied, step S
At 75, it is determined whether or not the following equation (4) holds. If so, Pcld is set to ΔD at step S76.
And the process proceeds to step S13.

Int (t / T _M ) = 0 (4) where ΔD is the amount of transmission power attenuation, and T _M is the second transmission power control transmission power reduction period defined by time in units of the transmission power control period. Represents If Expression (4) does not hold in Step S75, the process proceeds to Step S13.

In FIG. 1, the transmission power of the first transmission power control is determined by the maximum pilot signal reception level, but the transmission power of the first transmission power control is determined by the weighted sum of all pilot signal reception levels. By determining
It is possible to keep the interference to these base stations low when the propagation loss to a plurality of base stations is larger than the path loss to the minimum propagation loss base station during connection but becomes relatively small. FIG. 5 shows a first transmission power control unit FST in that case.
5 is a control flow showing a second embodiment of the present invention.

That is, in step S80, the maximum reception level Pm of the pilot signal reception powers P _I1 -P _IN , the weighted sum Pac of the pilot signal reception levels of the connected base stations, and the pilot signal reception level of the non-connected base stations Weighted sum Pau, total pilot signal received power P _I1
Calculated weighted sum P _S of to P _IN determination, in step S81, the following equation the transmit power Popn for the first transmission power control so that the reception level of the desired wave in the base station becomes D1 (5) I do.

[0063] _{Popn = (Pt / P S)} × D1 (5) Thereafter, the process proceeds to step S03, the control flow of FIG. 1 described above is executed.

In the above-described embodiment, a case has been described in which the weighted sum of the reception levels of the pilot signals of the connected or unconnected base stations is calculated. It is needless to say that the case where the reception levels of the pilot signals are compared, that is, the case where equal weights are applied to all the reception levels is included. In addition, the present invention naturally includes a case where only one base station is connected and one base station is not connected, and a single reception level from both base stations is compared with each other. Further, the reception level is represented by electric field strength, propagation loss and the like. Although only the reception level of the pilot signal has been described, other factors may be used as long as the handoff period can be specified.

[0065]

According to the present invention, when the weighted sum of the pilot signal reception levels at the non-connected base station exceeds the weighted sum of the pilot signal reception levels at the connected base station, the transmission power control is performed. By suppressing the power increase, it is possible to suppress excessive transmission power emitted by the mobile station during a period until the connection processing with the unconnected base station is completed, and as a result, to suppress interference given to the unconnected base station. Can be.

[Brief description of the drawings]

FIG. 1 is a transmission power control flow chart showing a first embodiment of the present invention.

FIG. 2 is a control flow chart showing a second embodiment of a second transmission power control unit in the present invention.

FIG. 3 is a control flow chart showing a third embodiment of the second transmission power control section in the present invention.

FIG. 4 is a control flowchart showing a fourth embodiment of the second transmission power control unit in the present invention.

FIG. 5 is a control flowchart showing a second embodiment of the first transmission power control unit in the present invention.

FIG. 6 is a diagram illustrating a time transition of mobile station transmission power according to the transmission power control method of the present invention.

FIG. 7 is a diagram illustrating an example of a case where a mobile station suddenly improves visibility with a non-connected base station.

FIG. 8 is a block diagram of a part related to transmission power control in a base station.

FIG. 9 is a block diagram of a portion related to transmission power control in a mobile station.

FIG. 10 is a control flowchart showing an example of a conventional transmission power control method.

FIG. 11 is a diagram showing a temporal transition of mobile station transmission power according to a conventional transmission power control method.

[Explanation of symbols]

101 Transmission spread RF signal generation unit 102, 103 Variable output amplifier 104, 201 Transmission / reception shared device 105, 202 RF unit 106 Down converter ds0 Despreader dc0 Receive data demodulator bd0 Transmission power control bit detector mf0 Matching filter pd0 Path detector ld0 Pilot level measurement unit CTL Transmission power control unit 203 Desired signal level measurement unit 204 Comparator 205, 206 Transmission power control bit 207 Transmission power control bit insertion unit 208 Transmission signal 209 Pilot spread signal 210 Spreader 211 Adder 212 Modulator 213 Amplification devices P _{I1 to} P _IN Pilot signal reception level N Number of base stations that can receive pilot signals Popn First transmission power control transmission power Pt Pilot signal transmission power Pm Maximum pilot signal reception level D1 Desired signal level Pomax First transmission power control maximum transmission power Pomin First transmission power control minimum transmission power ΔP, ΔP _S , ΔP _L , ΔP _F , ΔP ₊ , ΔP _{S +} , ΔD
Transmission power increase / decrease amount Bpc1 to BpcM Received transmission power control bits M Number of connected base stations Pcld, Pcld 'Second transmission power control transmission power Pcmax Second transmission power control maximum transmission power Pcmin Second transmission power control minimum transmission power T1 Base Time at which station becomes line-of-sight position T2 Time at which connection processing with base station is completed Dh Time required for connection processing with base station B01-B05 Building R1, R2 Street A01 Area of line-of-sight BS # A, BS # B Base station MS01 Mobile station SND Second transmission power control unit FST First transmission power control unit t Absolute time Tm in units of transmission power control period, T _M Given by ratio to transmission power reduction period k Tm of second transmission power control Transmission power reduction cycle of second transmission power control int () Function representing truncation integer conversion Pac Connected base station Sum of pilot signal reception level weights Pau Sum of reception level weights of pilot signals from unconnected base stations P _S Sum of reception level weights of pilot signals from all base stations k _i Weight factor for base station #i

Claims (12)

[Claims] 1. A plurality of base stations each of which broadcasts a unique pilot signal, and a plurality of mobile stations which perform communication while sequentially controlling transmission power based on a control command from a connected base station among the base stations. In the transmission power control method for a code division multiplexed cellular mobile radio communication system, each of the mobile stations periodically detects a pilot signal level from the plurality of base stations, and simultaneously connects to the plurality of base stations. In the case where the weighted sum of pilot signal reception levels from the unconnected base station exceeds the weighted sum of pilot signal reception levels from the connected base station, Lower the station transmit power,
And a transmission power control method operable to suppress an increase in transmission power of the mobile station. 2. A mobile station comprising: a plurality of base stations each broadcasting a unique pilot signal; and a plurality of mobile stations communicating with the base station, wherein the mobile station controls transmission power based on a reception level of the pilot signal. Code division multiplexing cellular mobile radio, comprising: first transmission power control means for increasing / decreasing, and second transmission power control means for increasing / decreasing the transmission power by a control step size based on a control command from a connected base station. A transmission power control method for a communication system, comprising: receiving the pilot signals of the plurality of base stations; determining transmission power in inverse proportion to a maximum reception level among the pilot signal reception levels; Is the weighted sum of the pilot signal reception levels of all the connected base stations. And whether the determining whether more than the result of the determination, when said pilot signal reception level weighted sum of the non-connection base station exceeds a pilot signal reception level weighted sum of the connection in the base station,
Setting the control step size small;
When the sum of the pilot signal reception level weights of the non-connected base stations does not exceed the sum of the pilot signal reception level weights of the connected base stations, the control step size is set to be large. Transmission power control method. 3. If the result of the determination is that the pilot signal reception level weighted sum of the non-connected base station exceeds the pilot signal reception level weighted sum of the connected base station, When the control step size used at the time of increase is set small, the pilot signal reception level weighted sum of the non-connected base station does not exceed the pilot signal reception level weighted sum of the connected base station, and at the time of power reduction, the control is performed. 3. The transmission power control method according to claim 2, wherein the step size is set large. 4. When the weighted sum of pilot signal reception levels of the non-connected base station exceeds the weighted sum of pilot signal reception levels of the connected base station as a result of the determination, The transmission power of the mobile station during the minimum output, the pilot signal reception level weighted sum of the non-connected base station does not exceed the pilot signal reception level weighted sum of the connected base station, and other than the fixed period 3. The transmission power control method according to claim 2, wherein the control by the first and second transmission power control means is performed. 5. When the sum of pilot signal reception level weights of the non-connected base station exceeds the pilot signal reception level weighted sum of the connected base station as a result of the determination, the transmission power of the mobile station is reduced. If the sum of the pilot signal reception level weights of the non-connected base stations does not exceed the sum of the pilot signal reception level weights of the non-connected base stations, 3. The transmission power control method according to claim 2, wherein the control by the first and second transmission power control means is performed. 6. The transmission power control method according to claim 2, wherein the transmission power in said first transmission power control means is determined in inverse proportion to a weighted sum of reception levels of all said pilot signals. 7. A plurality of base stations each of which broadcasts a unique pilot signal, and a plurality of mobile stations which perform communication while sequentially controlling transmission power based on a control command from a connected base station among the base stations. In the code division multiplexing cellular mobile radio communication system, each of the mobile stations periodically detects a pilot signal level from the plurality of base stations and determines whether or not the mobile station is simultaneously connected to the plurality of base stations. In the case where the weighted sum of pilot signal reception levels from the unconnected base station exceeds the weighted sum of pilot signal reception levels from the connected base station, the mobile station transmission power is reduced. ,
And a control unit operable to suppress an increase in transmission power of the mobile station. 8. A mobile station transmission power control method in a wireless communication system, comprising a plurality of base stations and mobile stations, and performing a handoff operation during a handoff period, wherein the mobile station switches the base stations.
A mobile station transmission power control method, comprising: a power suppression step of reducing transmission power of the mobile station during the handoff period to reduce interference between wireless channels. 9. The power control method according to claim 8, wherein the power control step includes: receiving a plurality of pilot signals from the base station; and determining a power control amount by referring to each reception level of the pilot signal. A mobile station transmission power control method comprising: 10. The power control step according to claim 9, wherein the power suppressing step is a step of dividing the base station into a first group of base stations connected to the mobile station and a second group of base stations not connected to the mobile station. Comparing a first received pilot signal level associated with a first group of base stations with a second received pilot signal level associated with a second group of base stations;
Detecting that the level of the received pilot signal exceeds the first received pilot signal level, and determining the power suppression amount. 11. The mobile station transmission power control method according to claim 10, wherein the radio channel is defined by a common frequency. 12. A mobile station used in a wireless communication system having a plurality of base stations, wherein the handoff period is
Means for reducing transmission power and mitigating interference between wireless channels.