JP4604611B2 - Base station selection type transmission power control method, base station apparatus and mobile station - Google Patents

Description

  The present invention relates to a transmission power control method and a base station apparatus in a cellular system, and more particularly to a base station selection type transmission power control method and a base station apparatus for updating a main base station state.

  In a cellular system in which a plurality of base stations are arranged on a service area and a mobile station is connected to and communicates with the nearest base station, when the mobile station moves, the connected base station is switched (handover). . In a cellular system or the like to which code division multiple access is applied, a handover control method that can eliminate a line disconnection associated with base station connection switching is applied. This technique, called soft handover, connects to the switching destination base station while maintaining the connection with the switching source base station, and performs simultaneous communication between multiple base stations and the mobile station, thereby preventing instantaneous line interruption. Avoid occurrence. One mobile station transmits and receives the same information to and from a plurality of base stations, so that the effect of site diversity is obtained and a good call is achieved.

  However, when soft handover is applied to the downlink, a plurality of base stations transmit signals to the mobile station at the same time, which causes great interference to neighboring cells. A downlink transmission power control method (scheme A) described in Non-Patent Document 1 is known as a technique for suppressing such interference increase during downlink soft handover. Hereinafter, the outline of the method A will be described with reference to FIGS. In FIGS. 4 to 10, only components necessary for the method A are extracted and described.

  FIG. 4 is a diagram showing a configuration of a mobile station to which method A is applied. The downlink signal received from the antenna ANT is converted into a baseband signal by the down converter A-002 via the coupler A-001. A pilot signal from each base station in soft handover included in the baseband signal is received by a pilot receiver A-003, and its reception strength or reception quality is measured. This measurement result is input to the main base station determination unit A-004, and the base station having the maximum reception strength or the maximum reception quality is selected, and this is set as the main base station. The determination result of the main base station is input to the base station selection signal generator A-005, and a base station selection signal corresponding to the base station number assigned to the main base station is generated. The base station selection signal is input to the control signal generator A-006 and is input to the combiner A-007 together with other control signals such as a transmission power control signal. The uplink information signal generated by the uplink information signal generator A-008 is also input to the combiner A-007. After the control signal and the uplink information signal are combined in the combiner A-007, the output signal is input to the upconverter A-009, and further through the amplifier A-010, the combiner A-001 and the antenna ANT are connected. To the connected base station.

  FIG. 5 shows a frame configuration assumed in the present invention. The frame D-001 includes Fn slots D-002, and a serial number is assigned to each slot in the frame as shown in FIG.

  The transmission of the base station selection signal will be schematically described with reference to FIG. Each base station in soft handover is assigned a base station selection codeword consisting of a plurality of bit strings for identifying each base station. By configuring the base station selection code word with a plurality of bit strings, signal redundancy is provided, and transmission errors caused by noise, fading, and the like are reduced. E-002 shows an example of the base station selection codeword. A dedicated field E-001 for transmitting a part of the base station selection codeword is provided in the uplink slot E-003. Each part of the base station selection codeword consisting of a plurality of bit strings is shown in FIG. And is transmitted via a dedicated field E-001. In this way, the base station selection control cycle E-004 extends over a plurality of slots in order to transmit a base station selection code word composed of a plurality of bit strings. The dedicated field E-001 can accommodate a plurality of bits, and the base station selection control period E-004 can be shortened as the number of bits that can be accommodated is large.

  Next, the configuration of a base station to which method A is applied will be described using FIG. The uplink signal received from the antenna ANT is input to the down converter B-002 via the coupler B-001. The uplink received signal converted into the baseband signal by down converter B-002 is input to transmission power control signal demodulator B-003 and base station selection signal demodulator B-004, respectively. Transmission power control signal demodulator B-003 demodulates the transmission power control signal included in the uplink reception signal, and the demodulated transmission power signal is input to transmission power control section B-005. The transmission power control unit B-005 updates the internal transmission power value P1 from the demodulated transmission power control signal, and P1 is input to the main base station state update unit B-006. On the other hand, the base station selection signal demodulator B-004 demodulates the base station selection codeword included in the baseband signal, and the demodulated base station selection codeword is input to the main base station state update unit B-006. Is done. Main base station state updating section B-006 updates actual transmission power value P2 based on internal transmission power value P1 and the base station selection signal, and P2 is input to output controller B-008. The output controller B-008 receives the downlink signal generated by the downlink transmission signal generator B-007, and performs output control so that the output of the downlink signal becomes the actual transmission power value P2. The downlink transmission signal whose output is controlled by the output controller B-008 is frequency-converted by the up-converter B-009, and then transmitted to the mobile station via the amplifier B-010, the coupler B-001, and the antenna ANT. .

  The operation of the main base station state update unit B-006 in FIG. 7 will be described in more detail with reference to FIG. Based on the base station selection codeword demodulated by the base station selection signal demodulator B-004, the base station identification number is determined in C-001. In C-002, it is determined whether or not the determination result of the base station identification number is equal to the identification number of the own base station. If equal, the state of the own base station is set to the main base station state in C-003 and actual transmission is performed. The power value P2 is set equal to the internal transmission power value P1. On the other hand, if it is determined in C-002 that the determination result of the base station identification number is not the identification number of the own base station, the state of the own base station is set as a non-main base station in C-004, and the actual transmission power value Set P2 to the minimum transmission power value Pmin. Here, Pmin may be zero.

  As described above, in method A, transmission output is turned on and off at each base station based on the base station selection signal transmitted from the mobile station. Thereby, it is avoided that a plurality of base stations simultaneously emit the same signal to one mobile station, that is, interference given to neighboring cells is suppressed. As a result, a high line capacity can be achieved.

Furukawa, IEICE Technical Report, RCS97-218, February 1998, pp. 40, Chapter 2

  In each base station and each mobile station of the cellular system, measurement of pilot signals and interference signals from neighboring cells is periodically performed for the purpose of use for handover control and call admission control. When the measurement is performed at the base station, a method of performing more accurate measurement by temporarily stopping transmission from the mobile station connected to the base station is used. In addition, in the case of packet transmission or for the purpose of suppressing uplink interference when there is no sound, the transmission of the mobile station may be temporarily stopped during a call.

  FIG. 9 is a diagram illustrating a state of an uplink reception signal when transmission of a part of the uplink transmission signal is stopped. F-003 represents a slot and F-004 represents a dedicated field for transmitting a base station selection codeword. When transmission is stopped during the period of F-001, a base station selection codeword included in the uplink reception signal is lost as in F-002. In this way, when transmission from a mobile station in a call is temporarily stopped, a part or all of the base station selection signal required in method A is lost, and the reliability of base station selection is impaired. It was.

  During soft handover, a plurality of base stations transmit the same signal to one mobile station. At this time, the transmission timing of the signal transmitted by each base station is adjusted and transmitted so that the reception timing received by the mobile station falls within a certain allowable range. Since the propagation distance between each base station and mobile station is different, the transmission timing is different for each base station. On the other hand, uplink signals from mobile stations received by the base stations are received at different reception timings due to differences in propagation distance.

  In scheme A, each base station in the same soft handover set refers to the base station selection information transmitted from the mobile station to determine whether or not its own station can be output. As described above, since the reception timing of the uplink signal received at each base station is different, the reception timing is different for each base station even for the same base station selection information. In addition, since the transmission timing of the downlink signal transmitted by each base station is also different as described above, as a result of the above, the timing at which each base station actually updates the output after judging whether or not the output is possible from reception of the base station selection signal Depending on the situation, there may occur a case in which the update timing of the main base station cannot be synchronized at the reception point of the mobile station.

  FIG. 10 is used to explain in more detail the situation in which the reception timing of the mobile station is not synchronized with the update timing of the main base station. G-001 represents a slot, and the number shown in each slot represents the serial number of the slot. G-002 and G-003 respectively indicate downlink transmission signals transmitted from the base station group undergoing soft handover. G-002 represents a downlink transmission signal transmitted from the base station 1, and G-003 represents a downlink transmission signal transmitted from the base station 2. The transmission signals are received as G-004 and G-005 at the mobile station. Both downlink transmission signals G-002 and G-003 are transmitted with their transmission timings adjusted so that the reception timings at the mobile stations are aligned. As a result, as in G-004 and G-005, the reception timing of the downlink reception signal from each base station received by the mobile station is uniform. The transmission timing of the downlink transmission signals G-002 and G-003 varies depending on the length of the propagation delay G-012. The uplink transmission signal G-006 transmitted from the mobile station is transmitted after being delayed by the transmission / reception timing offset G-013 from the reception timing of the downlink reception signals G-004 and G-005. The uplink transmission signal G-006 is received at different reception timings such as G-007 and G-008 by the respective base stations, due to the propagation delay G-014. A part of the base station selection codeword is transmitted on the dedicated fields G-020 and G-021 to the slots of the uplink reception signals G-007 and G-008. Assuming that transmission of one base station selection codeword is completed at G-020, G-021, that is, the serial number 14 of the slot, each base station receives this, and from the received base station selection codeword, The main base station state described using 8 is updated. At this time, the update timing is updated in the G-016 slot in the base station 1 and in the G-017 slot in the base station 2. The serial numbers of the slots in which the main base station state is updated are G-016 and G-017, 2 and 1, respectively. As a result, the update timing of the main base station state observed by the mobile station is G- Deviation occurs like 018 and G-019.

  As described above, when a shift occurs in the update timing of the main base station at the reception point of the mobile station, the base station selection period is constant, so that a downlink reception signal is lost, or the update timing is updated in the mobile station. There is a problem that an additional circuit is required to keep track of the above.

  A first object of the present invention is to provide a main base station state updating method for guaranteeing a stable operation even when a base station selection signal is lost.

  A second object of the present invention is to provide a main base station state update method that can synchronize with the update timing of the main base station at the reception point of the mobile station.

According to the present invention, the mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and sets the base station selection signal in soft handover state. Is a transmission power control method in a wireless communication system that controls transmission power of a downlink signal according to a received base station selection signal in each base station, and at the time of replacement of a main base station The base station determines the update timing of the main base station state in the base station so that the main base station change of the downlink signal received at the mobile station is performed in synchronization between the main base stations before and after the change. Set as slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is the number of slots included in one frame) determined based on the slot number j that received the selection signal. If the base station selection signal does not indicate its own base station and the missing amount of the base station selection signal is equal to or less than the threshold at the update timing of the main base station status, Power control is performed, and in other cases, power control is performed as a main base station.

According to the present invention, a mobile station selects one or a plurality of main base stations from a plurality of base stations that are in a soft handover state with the mobile station, and generates a base station selection signal. A base station device that receives the base station selection signal transmitted to the group and controls transmission power of the downlink signal according to the received base station selection signal, and at the time of replacement of the main base station, The base station receives the base station selection signal and the update timing of the main base station status in the base station so that the main base station change of the received downlink signal is performed in synchronization between the main base stations before and after the change. Set as slot number (j + Tos) mod Fn (Tos is the number of standby slots, Fn is the number of slots included in one frame) determined based on the slot number j If the base station selection signal does not indicate its own base station at the timing, and the missing amount of the base station selection signal is less than or equal to the threshold value, power control is performed as a non-primary base station. Is characterized in that power control is performed as a main base station.

According to the present invention, a base station selection signal is generated by selecting one or a plurality of main base stations from a plurality of base stations in a soft handover state with the own mobile station, and the base station selection signal is transmitted to a base in a soft handover state. A mobile station that transmits to a station group and controls transmission power of a downlink signal according to a base station selection signal received at each base station, and at the time of replacement of the main base station at the base station, the mobile station The base station receives the base station selection signal at the update timing of the main base station status at the base station so that the main base station change of the downlink signal received at the base station is synchronized with each other before and after the change. The slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is the number of slots included in one frame) is set as the slot number (j + Tos) determined based on the determined slot number j. If the base station selection signal does not indicate its own base station and the missing amount of the base station selection signal is equal to or less than a threshold value, the power control is performed as a non-main base station. In other cases, power control is performed as a main base station, and a downlink signal is received at a set update timing.

According to the present invention, a mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and performs a soft handover of the base station selection signal. A wireless communication system for transmitting to a base station group in a state and controlling transmission power of a downlink signal according to a received base station selection signal in each base station, wherein the base station transmits a base station transmitted from a mobile station When the selection signal is received and the main base station is changed, the main base station change of the downlink signal received at the mobile station is performed in synchronization with each other between the main base stations before and after the change. The update timing of the main base station state is determined based on the slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is 1 frame) determined based on the slot number j at which the base station received the base station selection signal. The base station selection signal does not indicate its own base station and the missing amount of the base station selection signal is less than the threshold at the time of update of the main base station status. In some cases, power control is performed as a non-main base station, and in other cases, power control is performed as a main base station.
Further, according to the present invention, the mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and is in soft handover state A transmission power control method in a base station apparatus that receives a base station selection signal transmitted to a group of base stations and controls transmission power of a downlink signal according to the received base station selection signal, wherein In this case, the update timing of the main base station state in the base station is changed so that the main base station change of the downlink signal received in the mobile station is performed in synchronization between the main base stations before and after the change. Slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is the number of slots included in one frame) determined based on the slot number j from which the base station selection signal is received If the base station selection signal does not indicate its own base station and the missing amount of the base station selection signal is equal to or less than the threshold at the update timing of the main base station status, the non-main base Power control is performed as a station, and power control is performed as a main base station in other cases.
Further, according to the present invention, the mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and is in soft handover state A program for causing a computer to execute a transmission power control method in a base station apparatus that receives the base station selection signal transmitted to the base station group and controls transmission power of a downlink signal according to the received base station selection signal The recording medium is a recording medium, in which when the main base station is changed, the main base station change of the downlink signal received at the mobile station is performed in synchronization with each other between the main base stations before and after the change. The update timing of the main base station state in the station is determined based on the slot number (j + Tos) mod Fn (Tos) determined based on the slot number j from which the base station received the base station selection signal. Is the number of standby slots, Fn is the number of slots included in one frame), and the base station selection signal does not indicate its own base station at the update timing of the main base station state, and the base station is selected When the amount of signal loss is equal to or less than a threshold value, power control is performed as a non-main base station, and in other cases, power control is performed as a main base station.

  According to the embodiment shown in FIG. 1, when the base station selection codeword received by the base station is lost more than a certain amount due to the temporary stop of the uplink transmission signal, the base station selection signal actually transmitted Regardless of whether the base station is always in the main base station state, it is possible to reduce misjudgment to a non-main base station due to reception error of the base station selection signal and maintain stable downlink reception quality. Become.

  According to the embodiment shown in FIG. 2, the update of the main base station state is performed synchronously in the downlink signal received by the mobile station, so that the loss of the downlink received signal due to the synchronization shift is avoided. Further, an additional circuit for monitoring the update timing at any time in the mobile station becomes unnecessary.

  FIG. 1 is a configuration diagram showing an embodiment of the present invention, and particularly shows a configuration for avoiding a problem due to lack of a base station selection signal. This block diagram corresponds to the main base station state update unit shown in FIG. In the base station, the missing amount of the base station selection signal is checked, and when the missing amount exceeds a threshold value, the transmission power is not stopped or suppressed. Hereinafter, a more specific configuration will be described.

  In the base station selection codeword output from the base station selection signal demodulator B-004, it is determined in H-001 whether the signal loss amount exceeds the threshold value. Here, the signal loss amount is given by the number of bits, the ratio of the number of missing bits to the total number of bits included in the base station selection codeword, and the like. In addition, the threshold value may vary depending on the length of the base station codeword. When the signal loss amount exceeds a threshold value, it is determined that the reliability of the demodulated base station selection codeword is poor, so in H-005, it is always always regardless of whether it is originally the main base station or not. The main base station state is set, and transmission power is not suppressed. When the main base station is set in H-005, the actual transmission power value P2 is set to the internal transmission power value P1. On the other hand, if the signal loss amount is equal to or less than the threshold in H-001, the base station identification number is determined from the base station selection codeword in H-003, and further, the base station identification is performed in H-002. It is determined whether or not the number matches the identification number of the own base station. If the base station identification number matches the identification number of the own base station, the state of the own base station is changed to the main base station state in H-005. On the other hand, if the base station identification number does not match the identification number of the own base station, the state of the own base station is set to a non-main base station state in H-004, and the actual transmission power value P2 is set to the minimum transmission power value Pmin. Set. Here, the minimum transmission power value Pmin can be zero. When determining the non-primary base station, the reception quality of the base station selection codeword is observed, and if the reception quality is less than the desired value, the reliability of the base station selection codeword is still considered to be low. In some cases, the state of the base station is determined as the main base station.

  According to the embodiment of the main base station state update unit shown in FIG. 1, when the amount of missing base station selection signals received by the base station exceeds a threshold, that is, the demodulated base station selection codeword When it seems that the reliability is poor, whether it is the main base station or not, the state of the own base station is always set as the main base station state so that transmission power is not suppressed.

  FIG. 2, like FIG. 1, is a block diagram showing an embodiment of the present invention, and particularly shows a configuration for avoiding problems caused by a shift in the update timing of the main base station state. As in FIG. 1, this configuration diagram also corresponds to the main base station state update unit shown in FIG. In all base stations, the output state is updated from downlink slots having the same serial number. Hereinafter, the operation will be described more specifically.

  In I-001, the base station identification number is determined from the base station selection codeword output from the base station selection signal demodulator B-004. In I-002, after setting the slot number in which the final part of the base station selection codeword is transmitted as j, the process waits until the current slot number satisfies the following expression (1).

  Formula (1) (j + Tos) mod Fn Here, Tos represents the state update waiting time, and Fn represents the number of slots included in one frame. X mod Y is an operator that gives the remainder when X is divided by Y. After waiting in I-003, it is determined in I-004 whether or not the base station identification number matches the identification number of the own base station. In the base station state, the actual transmission power value P2 is set to the internal transmission power value P1. If they do not match, in I-006, the state of the base station is set to the non-main base station state, and the actual transmission power value P2 is set to the minimum transmission power value Pmin. Here, Pmin can be zero. In I-006, when setting the state of the own base station as a non-main base station, refer to the reception quality of the base station selection codeword, and set it only when good reception quality is obtained. It can happen. If good reception quality is not achieved, it is considered that the reliability of the base station codeword is poor. In this case, the main base station state is always set whether or not it is the main base station.

  The operation of the main base station state update unit shown in FIG. 2 will be described in detail with reference to FIG. FIG. 3 is a diagram schematically showing the update timing of the main base station state in the base station, and is a diagram corresponding to FIG. 10 described in the related art. J-001 represents a slot, and the number shown in each slot represents the serial number of the slot. J-002 and J-003 indicate downlink transmission signals transmitted from the base stations in the soft handover, respectively. J-002 represents a downlink transmission signal transmitted from the base station 1, and J-003 represents a downlink transmission signal transmitted from the base station 2. Each of the transmission signals is received as J-004 and J-005 at the mobile station. Both downlink transmission signals J-002 and J-003 are transmitted with their transmission timings adjusted so that the reception timings at the mobile stations are aligned. As a result, as in J-004 and J-005, the reception timing of the downlink reception signal from each base station received by the mobile station is uniform. The transmission timings of the downlink transmission signals J-002 and J-003 vary depending on the length of the propagation delay J-012. The uplink transmission signal J-006 transmitted from the mobile station is transmitted after being delayed by the transmission / reception timing offset J-013 from the reception timing of the downlink reception signals J-004 and J-005. The uplink transmission signal J-006 is received at different reception timings such as J-007 and J-008 at the respective base stations by the propagation delay J-014. A part of the base station selection codeword is transmitted on the dedicated fields J-020 and J-021 to the slots of the uplink reception signals J-007 and J-008. Now, assuming that transmission of one base station selection codeword is completed at J-020, J-021, that is, the serial number 14 of the slot, each base station receives this, and from the received base station selection codeword, The main base station state described using 2 is updated. When the state update waiting time Tos is set to 3, the slot serial number j of the last part of the base station selection codeword is 14 and the number of slots Fn included in the frame is 15 as shown in FIG. The state update timing given by is the slot with slot serial number 2. Therefore, the update of the main base station state is updated in the slot of J-016 in the base station 1 and in the slot of J-017 in the base station 2. As a result, the update timing of the main base station state observed by the mobile station is synchronized as in J-018 and J-019, and no deviation occurs.

  In order to achieve high-speed state switching, it is preferable that the state update waiting time Tos is short. Since the transmission path delay, the processing delay of the base station apparatus, and the like can change, Tos can be varied during a call. In addition, Tos may be varied depending on the value of the reception slot serial number j of the last part of the base station selection codeword. By changing Tos by j, it is possible to control the main base station state update timing in the mobile station to a desired timing.

  The configuration shown in FIG. 1 may be combined with the configuration of the main base station state update unit shown in FIG. 2 and operated simultaneously. In this configuration, in the comparison between the receiving base station identification number in I-004 and the identification number of the own base station, a condition that the missing amount of the codeword is equal to or less than the threshold is added, and the receiving base station identification number is The process proceeds to I-005 only when the ID number matches the ID number and the missing amount of the code word is less than or equal to the threshold value. Further, as described above, a condition that the reception quality of the codeword satisfies the desired quality may be added.

The figure which shows the structure for avoiding the problem regarding the update of the main base station state of this invention, especially the loss of a base station selection codeword The figure which shows the structure for avoiding the problem regarding the synchronization shift of the main base station state update of this invention, especially the main base station state update The figure which shows the mode of the main base station state update of this invention The figure which shows embodiment of the mobile station to which the base station selection system was applied Diagram showing frame configuration Diagram showing transmission of base station selection signal The figure which shows embodiment of the base station to which the base station selection system was applied The figure which shows the conventional base station selection state update method The figure which shows the mode of an upstream received signal when an upstream transmission signal is stopped The figure which shows the state of the conventional main base station state update

Explanation of symbols

ANT: Antenna
Fn: Number of slots included in one frame
P1: Internal transmission power value
P2: Actual transmission power value
Pmin: Minimum transmission power value j: Slot number in which the last part of the base station selection codeword is transmitted
Tos: Main base station status update wait time (number of slots)

Claims (6)

A mobile station and a base station, wherein the mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover with the mobile station to generate a base station selection signal, and selects the base station signal was transmitted to the base stations in the soft handover state, the a transmission power control method in a radio communication system for controlling transmission power of the downlink signal in response to the base station selection signal received at each base station,
When the main base station is changed, the main base station in the base station is configured such that the main base station change of the downlink signal received in the mobile station is performed in synchronization between the main base stations before and after the change. The state update timing is determined based on the slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is a slot included in one frame), which is determined based on the slot number j at which the base station has received the base station selection signal. is set as the number),
At the update timing of the main base station state,
When the base station selection signal does not indicate its own base station and the amount of missing base station selection signal is equal to or less than a threshold value, power control is performed as a non-main base station,
Transmission power control method Carriage you and performs power control as the main base station in other cases. The mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and is transmitted to the base station group in soft handover state receiving the base station selection signal, a base station apparatus for controlling transmission power of the downlink signal in response to the base station selection signal received,
When the main base station is changed, the main base station in the base station is configured such that the main base station change of the downlink signal received in the mobile station is performed in synchronization between the main base stations before and after the change. The state update timing is determined based on the slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is a slot included in one frame), which is determined based on the slot number j at which the base station has received the base station selection signal. is set as the number),
At the update timing of the main base station state,
When the base station selection signal does not indicate its own base station and the amount of missing base station selection signal is equal to or less than a threshold value, power control is performed as a non-main base station,
The base station apparatus you and performs power control as the primary base station otherwise. A base station selection signal is generated by selecting one or a plurality of main base stations from a plurality of base stations in soft handover state with the own mobile station, and the base station selection signal is transmitted to a group of base stations in soft handover state the a mobile station for controlling a transmission power of the downlink signal in response to the base station selection signal received by each base station at the base station, upon replacement of the main base station, the mobile station The base station selects the base station for the update timing of the main base station state in the base station so that the main base station change of the downlink signal received at the base station is synchronized between the main base stations before and after the change. Set as slot number (j + Tos) mod Fn (Tos is the number of standby slots, Fn is the number of slots included in one frame) determined based on the slot number j that received the signal ,
At the update timing of the main base station state, in the base station, when the base station selection signal does not indicate its own base station, and the missing amount of the base station selection signal is equal to or less than a threshold value A mobile station characterized in that it performs power control as a non-main base station, otherwise performs power control as a main base station, and receives the downlink signal at a set update timing. A mobile station and a base station, wherein the mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover with the mobile station to generate a base station selection signal, and selects the base station A radio communication system that transmits a signal to a base station group in a soft handover state, and controls transmission power of a downlink signal according to the received base station selection signal in each base station,
The base station receives the base station selection signal transmitted from the mobile station,
When the main base station is changed, the main base station in the base station is configured such that the main base station change of the downlink signal received in the mobile station is performed in synchronization between the main base stations before and after the change. The state update timing is determined based on the slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is a slot included in one frame), which is determined based on the slot number j at which the base station has received the base station selection signal. Number)
At the update timing of the main base station state,
If the base station selection signal does not indicate its own base station and the amount of missing base station selection signal is less than or equal to a threshold value, power control is performed as a non-main base station,
In other cases, a radio communication system that performs power control as a main base station. The mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and is transmitted to the base station group in soft handover state A transmission power control method in a base station apparatus that receives a base station selection signal and controls transmission power of a downlink signal according to the received base station selection signal,
When the main base station is changed, the main base station in the base station is configured such that the main base station change of the downlink signal received in the mobile station is performed in synchronization between the main base stations before and after the change. The state update timing is determined based on the slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is a slot included in one frame), which is determined based on the slot number j at which the base station has received the base station selection signal. Number)
At the update timing of the main base station state,
If the base station selection signal does not indicate its own base station and the amount of missing base station selection signal is less than or equal to a threshold value, power control is performed as a non-main base station,
In other cases, the transmission power control method is characterized in that power control is performed as a main base station. The mobile station selects one or a plurality of main base stations from a plurality of base stations in soft handover state with the mobile station, generates a base station selection signal, and is transmitted to the base station group in soft handover state A recording medium recording a program for causing a computer to execute a transmission power control method in a base station apparatus that receives a base station selection signal and controls transmission power of a downlink signal according to the received base station selection signal. ,
When the main base station is changed, the main base station in the base station is configured such that the main base station change of the downlink signal received in the mobile station is performed in synchronization between the main base stations before and after the change. The state update timing is determined based on the slot number (j + Tos) mod Fn (Tos is the number of standby slots and Fn is a slot included in one frame), which is determined based on the slot number j at which the base station has received the base station selection signal. Number)
At the update timing of the main base station state,
If the base station selection signal does not indicate its own base station and the amount of missing base station selection signal is less than or equal to a threshold value, power control is performed as a non-main base station,
In other cases, a recording medium recording a program having a process of performing power control as a main base station.

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