JP2011130058A - Transmission power control method of cellular system, mobile station, and transmission power control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the amount of communication processing and frequency resources for use in a base station. <P>SOLUTION: In a transmission power control method for a cellular system, a base station and a mobile station in a cell controlled by the base station perform wireless communication with each other. The base station transmits a transmission power control command to the mobile station in the cell. The mobile station preserves a history of transmission power control performed in response to the received transmission power control command, in association with the cell. When the mobile station becomes under the control of the base station again after moving out of the cell managed by the base station, transmission power control is performed using the history of transmission power control, which has been preserved when under the control of the base station. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication technology using a cellular system.

  In the field of wireless communication technology using a cellular system, transmission power control may be performed between a mobile station and a base station. For example, long term evolution (LTE) adopted by the standardization organization 3GPP is known as this type of wireless communication technology. LTE is a communication method that can accommodate more users in one base station while improving the throughput between the terminal and the base station as compared with W-CDMA. In realizing this, LTE has advanced functions such as transmission power control (TPC) using a sounding reference signal (SRS) defined in Non-Patent Document 1 and Non-Patent Document 2. Required by base stations. Along with this, base stations are also required to have higher processing capabilities.

  However, the processing capacity of the base station is limited. Therefore, the importance of algorithms that reduce the processing amount while satisfying the specifications is increasing. In particular, a function performed in units of transmission time intervals (TTI) such as TPC has a particularly large processing amount, and therefore it is important to reduce the processing amount.

  The TPC in LTE is performed by a method using SRS defined in Non-Patent Document 1 or Non-Patent Document 2 or a method shown in Patent Documents 1 and 2. In TPC, a base station receives an SRS and a demodulation reference signal (DMRS) transmitted from each terminal based on a set period, and a signal-to-interference ratio (SIR). This is done by calculating

3GPP TS 36.211 (V8.7.0), 'Physical Channels and Modulation', May 2009 3GPP TS 36.213 (V8.7.0), 'Physical layer procedures', May 2009

JP 2008-177965 A JP 2009-4924

  However, in the above-described conventional technology, the processing load on the base station when performing transmission power control between the mobile station and the base station is large. For example, even in LTE, TPC processing is performed for each terminal and in units of subframes, so that when the base station places many terminals under control, the processing load on the base station becomes very large. In addition, it is not preferable to occupy valuable frequency resources for TPC originally, but when the base station has a large number of terminals under control, many frequency resources are occupied by SRS. Become. This is because SRS occupies frequency resources designated for each terminal.

  Based on the above, it is desired to perform transmission power control while suppressing the processing amount of the base station as much as possible.

  The objective of this invention is providing the radio | wireless communication technique which solves the above-mentioned subject.

In order to achieve the above object, a method according to an aspect of the present invention is a transmission power control method for a cellular system that performs radio communication between a base station and a mobile station in a cell managed by the base station,
Transmitting a transmission power control command from the base station to the mobile station in the cell;
In the mobile station, a history of transmission power control performed according to the received transmission power control command is stored in association with the cell;
Determining whether the mobile station has returned to management of the base station again after being removed from management of the base station;
The transmission power control that was saved when the mobile station was under the management of the base station in the past when the mobile station was removed from the management of the base station and then returned to the management of the base station. And a step of performing transmission power control using the above history.

In order to achieve the above object, an apparatus according to one aspect of the present invention provides:
A mobile station that performs radio communication with the base station in a cell managed by the base station,
Means for receiving a transmission power control command from the base station;
Means for storing a history of transmission power control performed in response to the received transmission power control command in association with the cell;
After the mobile station is removed from the management of the base station, when the mobile station returns to the management of the base station again, the transmission power control stored when the mobile station was under the management of the base station in the past. Means for performing transmission power control using history;
It is characterized by having.

In order to achieve the above object, a program according to one aspect of the present invention is provided.
A transmission power control program executed by a mobile station that performs radio communication with the base station in a cell managed by the base station,
In the processor provided in the mobile station,
A function of receiving a transmission power control command from the base station;
A function of storing a history of transmission power control performed according to the received transmission power control command in association with the cell;
A function of determining whether the mobile station has returned to the management of the base station again after being removed from the management of the base station;
The transmission power control that was saved when the mobile station was under the management of the base station in the past when the mobile station was removed from the management of the base station and then returned to the management of the base station. A function to perform transmission power control using the history of
Is executed.

  According to the present invention, it is possible to perform transmission power control while suppressing the processing amount of the base station as much as possible.

It is a figure which shows the outline | summary of the communication system as 1st Embodiment of this invention. It is a figure which shows the outline | summary of the process performed with the communication system as 1st Embodiment of this invention. It is a figure which shows schematic structure of the mobile station contained in the communication system as 1st Embodiment of this invention. It is a figure which shows schematic structure of the base station contained in the communication system as 1st Embodiment of this invention. It is a figure explaining the TPC command used in the communication system as 1st Embodiment of this invention. It is a figure which shows the transmission power control log | history used in the communication system as 1st Embodiment of this invention. It is a figure which shows the hardware constitutions of the mobile station contained in the communication system as 1st Embodiment of this invention, and the flowchart of a process. It is a figure which shows the hardware constitutions of the base station contained in the communication system as 1st Embodiment of this invention, and the flowchart of a process. It is a figure which shows the effect by the communication system as 1st Embodiment of this invention. It is a figure which shows the effect by the communication system as 1st Embodiment of this invention. It is a figure for demonstrating the condition which should correspond with the communication system as 2nd Embodiment of this invention. It is a figure for demonstrating the condition which should correspond with the communication system as 2nd Embodiment of this invention. It is a figure which shows the flowchart of the process performed with the communication system as 2nd Embodiment of this invention. It is a figure for demonstrating the condition which can respond by the process shown to the flowchart of FIG. It is a figure for demonstrating the condition which can respond by the process shown to the flowchart of FIG. It is a figure which shows the flowchart of the process performed with the communication system as 2nd Embodiment of this invention. It is a figure for demonstrating the condition which can respond by the process shown in the flowchart of FIG. It is a figure which shows the flowchart of the process performed with the communication system as 2nd Embodiment of this invention. It is a figure for demonstrating the condition which can respond by the process shown to the flowchart of FIG. It is a figure which shows the effect by the communication system as 2nd Embodiment of this invention. It is a figure which shows the effect by the communication system as 2nd Embodiment of this invention. It is a figure which shows the flowchart of the process performed with the communication system as 3rd Embodiment of this invention. It is a figure which shows the effect by the communication system as 3rd Embodiment of this invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in the following embodiments are merely examples, and are not intended to limit the technical scope of the present invention only to them.

<First Embodiment>
(Outline of system configuration and operation)
FIG. 1 is a diagram showing an outline of a communication system as a first embodiment of the present invention. In particular, the communication system of this embodiment is a cellular system that performs wireless communication between a base station and a mobile station in a cell managed by the base station, and moves according to a transmission power control command transmitted by the base station. It is a cellular system in which a station controls transmission power. In FIG. 1, it is assumed that the mobile station 101 has once moved from the cell 103 managed by the base station 102 to another cell 104, 105 and then returned to the cell 103 managed by the base station 102 again. . In such a case, in the present embodiment, communication between the mobile station 101 and the base station 102 is re-established using the communication control history when the mobile station 101 belonged to the cell 103 in the past. Thereby, traffic between the mobile station 101 and the base station 102 can be reduced, and the processing amount and frequency resources of the base station 102 can be suppressed.

(Communication between base station and mobile station)
Communication between the mobile station 101 and the base station 102 will be described with reference to FIG. In response to an allocation request (scheduling request 201) from the mobile station 101, the base station 102 notifies an uplink transmission grant (USG) 202. Thereby, the base station 102 schedules uplink data transmission between a plurality of mobile stations. At this time, the USG 202 transmitted from the base station 102 to the mobile station 101 includes a transmission power control command (TPC command: Transmission Power Control Commands) as transmission power control information. The mobile station 101 transmits data to the base station 102 using an uplink shared data channel (PUSCH) using radio resources allocated by the USG 202. At this time, the mobile station 101 calculates transmission power corresponding to the wireless environment based on the TPC command in the USG 202, and transmits data using the calculated transmission power.

  The mobile station 101 also transmits channel quality information (CQI: Channel Quality Indicator) for scheduling at the base station 102 and an acknowledgment (ACK / NACK) on the uplink shared control channel. Then, a sounding reference signal (SRS) is transmitted in order to perform reception frequency measurement for uplink frequency domain scheduling and transmission power control.

(Schematic configuration of mobile station)
FIG. 3 shows the internal configuration of the mobile station 101 according to this embodiment. The mobile station 101 includes a TPC command receiving unit 301 that receives a TPC command from the base station 102, a transmission power calculating unit 302 that calculates transmission power from the received TPC command, and data transmission that transmits data with the calculated transmission power. Part 303.

  The TPC command has a value such as (0, 1, 2, 3), for example, and is converted into a power ratio α such as (−1 dB, 0 dB, 1 dB, 3 dB) using a conversion table 501 as shown in FIG. . The transmission power for data transmission is determined using these power ratios α and the immediately preceding transmission power (if there is no initial value of the transmission power). However, the numerical values given here are merely examples, and do not limit the present invention.

  The mobile station 101 includes a TPC history storage unit 304 that stores a TPC history, and a TPC history transmission unit 305 that transmits the TPC history read from the TPC history storage unit 304 to the base station 102.

  An example of the internal configuration of the TPC history storage unit 304 is shown in FIG. The TPC history storage unit 304 stores a transmission power control history corresponding to the transmission power control command as a TPC history. For example, initial transmission power and n times of TPC commands received in the past are stored in association with information (cell-specific ID) that identifies the base station that transmitted the TPC command. The TPC history storage unit 304 stores the initial transmission power and the TPC command together with the cell-specific identifier as a TPC history for a certain period T, and then discards it. For this reason, referring to FIG. 6, a cell including the mobile station 101 is a cell that establishes a link for the first time, or after a certain period of time has elapsed since the cell established a link in the past and released the link. Or not. However, the TPC history saved by the TPC history saving unit 304 is not limited to the TPC command format, and may be another value. Further, n and T can be changed by parameters. In this embodiment, the initial transmission power is fixed for each cell, and TPC control is started from the same initial transmission power value every time the control returns to the same cell.

  Further, the transmission power calculation unit 302 calculates transmission power based on the TPC history read from the TPC history storage unit 304. Alternatively, when the calculated transmission power value itself is stored in the TPC history storage unit 304, the transmission power may be transmitted to the data transmission unit 303 without using the transmission power calculation unit 302.

(Schematic configuration of base station)
The internal configuration of the base station 102 according to this embodiment is shown in FIG. The TPC history receiving unit 401 receives the TPC history transmitted from the mobile station 101 and notifies the scheduler 402 of the TPC history. The scheduler 402 performs the scheduling by treating the TPC history notified from the TPC history receiving unit 401 as a history actually transmitted to the mobile station 101.

  In this way, since TPC is performed by referring to the TPC history performed by the mobile station 101 in the past, SRS transmission / reception, SIR calculation processing, and the like can be omitted, and the processing amount of the base station and the frequency resources to be used are minimized Can be suppressed. Further, TPC equivalent to TPC using SRS can be performed.

(TPC control in mobile station 101)
TPC control in the mobile station 101 will be described with reference to FIG. The mobile station 101 includes a memory 1502, a communication unit 1503, and a processor 1501 that controls them as a hardware configuration. Then, the processor 1501 performs processing as shown in the flowchart.

  Specifically, first, whether the cell including the mobile station 101 is a cell that establishes a link for the first time, or whether the cell is a cell after a certain period of time has elapsed since the link was established and the link was released in the past. Is determined (S701). This can be easily determined by referring to the TPC history as shown in FIG. If it is determined that the cell is a first link establishment cell or a link establishment cell after a certain period of time has elapsed since the link was released, the mobile station 101 uses SRS or the like with the base station 102 as shown in FIG. TPC is performed (S703). At this time, the mobile station 101 stores the TPC execution history in the TPC history storage unit 304 as cell-specific information (S704).

  On the other hand, when it is determined that the cell has been released from the link within a certain period in the past (departed from management), the mobile station 101 reads the TPC history from the TPC history storage unit 304 when the relink is established (S705). ). Then, the TPC history transmission unit 305 of the mobile station 101 transmits the TPC history to the base station 102 (S706). Further, the transmission power calculation unit 302 determines the transmission power according to the TPC history read from the TPC history storage unit 304 (S707). At this time, first, the transmission power is obtained by multiplying the initial value of the transmission power read from the table 601 in FIG. 6 by the power ratio α obtained by referring to the conversion table 501 in FIG. 5 from the TPC history similarly read from the table 601. Is calculated. Thereafter, the transmission power is changed by multiplying the previous transmission power by the power ratio α obtained from the TPC history.

  Next, the mobile station 101 transmits an uplink shared channel (UL-SCH) (S708), and determines whether HARQ ACK responses to the UL-SCH are continuously returned (S709). If the HARQ ACK response comes back continuously, the reference of the TPC history is stopped, and the data transmission is continued with the transmission power fixed (S710). In other words, the transmission power control history that has been stored is used to transmit data while changing the transmission power, so that when normal data communication is established, the transmission power is fixed and data transmission is performed. Do.

  On the other hand, when the HARQ NACK response to the UL-SCH continues n times and all the TPC histories for n times included in the TPC history are read, the process proceeds to step S703 to switch to normal TPC. Then, the TPC history is stored in the TPC history storage unit 304 (S704).

(TPC control in the base station 102)
The TPC control in the base station 102 will be described with reference to FIG. As a hardware configuration, the base station 102 includes a memory 1602, a communication unit 1603, and a processor 1601 that controls them. Then, the processor 1601 performs processing as shown in the flowchart.

  First, the TPC history receiving unit 401 of the base station 102 receives the TPC history transmitted from the mobile station 101 (S801). Then, the received TPC history is notified to the scheduler 402 (S802). Next, the scheduler 402 regards the received TPC history as a TPC command notified to the mobile station 101 and registers it.

(Effect of this embodiment)
According to the above embodiment, the transmission power of the mobile station 101 is the same as that of the mobile station 101 using the power control history when the mobile station 101 belonged to the cell 103 in the past, as shown in FIGS. Re-establish communication with the base station 102. Thereby, traffic between the mobile station 101 and the base station 102 can be reduced, and the processing amount and frequency resources of the base station 102 can be suppressed. By using the TPC history in this way, transmission power control can be performed particularly effectively and efficiently when the target value of the previous time and this time are close, that is, when the mobile terminal is in the same location and the wireless environment hardly changes. Can be done.

Second Embodiment
Next, a second embodiment of the present invention will be described. In the first embodiment, the same initial transmission power value is used every time for the same cell (FIGS. 9 and 10), whereas in this embodiment, the initial transmission power value is changed according to the situation. . Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the case of the first embodiment, if the target transmission power value (= target transmission power value) is included in the range of the control power value that has transitioned during the previous TPC, the processing is performed by using the TPC history. The transmission power can be obtained while reducing the amount. However, when the target transmission power value is larger than the maximum transmission power at the previous TPC, the power becomes insufficient. On the other hand, if the initial power value has already exceeded the target transmission power value, the transmission power becomes excessive.

  Also, when returning to the original cell at the same location and environment, the target transmission power value is likely to be the same every time. Therefore, a method of setting the previous target transmission power value (final transmission power value of the TPC history) as the initial transmission power value can be proposed, and this has the effect that unnecessary transmission power control can be omitted. However, in FIG. 11, for example, although the initial power value is lower than the target transmission power value, the previous TPC history is in the direction of decreasing the power, so that the transmission power value is further decreased. On the other hand, in FIG. 12, since the initial power value has already exceeded the target transmission power value, ACKs are returned continuously, but since excessive transmission power is used, it cannot be said to be an appropriate TPC. .

  Therefore, the relationship between the previous initial power value, the previous target transmission power value, and the current target transmission power value corresponds to all patterns including FIG. 11 and FIG. Through the processing shown in FIG. Specifically, the processes in steps S705 to S711 in FIG. 7 are replaced with the flowcharts shown in FIGS. Here, either the last transmission power value of the previous transmission power control remaining in the transmission power control history or the initial transmission power value of the previous transmission power control is selectively used as the initial transmission power value. .

  First, in step S1301 in FIG. 13, the previous target transmission power value is set as the initial transmission power value. Next, in step S1303, it is determined whether or not ACK is continuously returned at that time. If ACKs are returned continuously, it means that the current target transmission power value is smaller than the previous target transmission power value, so control to lower the transmission power value must be performed.

  In step S1305, the previous target transmission power value is compared with the previous initial transmission power value. When the previous target transmission power value is smaller than the previous initial transmission power value, the previous transmission power control generally performs control to lower the transmission power value. In this case, the process proceeds to step S1315, and the current transmission power value is fixed to the previous target transmission power value. That is, as shown in FIG. 14, in the previous transmission power control, as a result of lowering the transmission power value, the target transmission power value has been reached, and normal communication is performed when the target transmission power value is used this time. Can be done. Therefore, in this case, it is considered that the current target transmission power value is the same as or slightly lower than the previous target transmission power value. Therefore, in that case, the previous target transmission power value is directly used as the current target transmission power value.

  On the other hand, if it is determined in step S1305 that the previous target transmission power value is larger than the previous initial transmission power value, the previous transmission power control generally performs control to increase the transmission power value as shown in FIG. It has been done. In addition, since ACK is continuously returned when the previous target transmission power value is set as the initial transmission power value, the current target transmission power value is smaller than the previous target transmission power value.

  In this case, since the transmission power value may be too large, the process proceeds to step S1307, and the previous TPC history is used in the reverse order of the time series to decrease the transmission power value. For example, if the stored TPC history is (-1, 0, 1, 3), it is used as (-3, -1, 0, 1). Then, the TPC history is finished (S1309) or lowered until the ACK is not returned continuously (S1311). Fix (S1313). Even if the transmission power is reduced to the initial transmission power, if the ACK is returned continuously, the target transmission power value is even smaller. Therefore, the TPC history cannot be used, and the process proceeds to step S1317 to perform normal TPC again. At that time, the TPC history is saved (S1319).

  Generally, since the history when the transmission power becomes stable often remains at the end of the TPC history, it is considered that a TPC command having a small absolute value such as 0 dB or 1, −1 dB remains. Therefore, when the TPC history is used in reverse order, the power fluctuation becomes small immediately after the start of TPC. When the previous target value and the current target value are relatively close to each other, the error is corrected and an effective TPC can be expected.

  Next, a case where ACK is not consecutive in step S1303 will be described. In this case, since the previous target transmission power value is smaller than the current target transmission power value, it means that normal communication could not be performed when the previous target transmission power value was set as the initial transmission power value. The processing in this case is shown in the flowchart of FIG.

  First, in FIG. 16, in step S1601, the previous target transmission power value and the previous initial power value are compared. When the previous target transmission power value is larger than the previous initial transmission power value, there is a possibility that the previous initial transmission power value ≦ the previous target transmission power value ≦ the current target transmission power value as shown in FIG. In this case, the transmission power is controlled using the TPC history after setting the previous target transmission power value as the current initial transmission power value (S1603). If a transmission power value with continuous ACK is found by the end of the TPC history (S1607), the process proceeds to step S1609, and the found transmission power value is fixedly used as the current target transmission power value. On the other hand, if a transmission power value with continuous ACK is not found even when the transmission power is changed using the TPC history, the process proceeds to step S1611 and normal TPC is performed again. At that time, the TPC history is saved (S1319).

  If the previous target transmission power value is equal to or smaller than the previous initial transmission power value in step S1601, there is a possibility that the previous initial transmission power value> the current target transmission power value> the previous target transmission power value as shown in FIG. In this case, processing according to the flowchart of FIG. 18 is performed. That is, first in step S1801, the previous initial transmission power value is set as the current initial transmission power value. Here, it is determined whether or not ACK is returned continuously (S1803), and if ACK is returned continuously, the transmission power value may be too large. Lower the power value. Then, the TPC history is finished (S1807) or lowered until the ACK is not returned continuously (S1809). If the ACK does not return continuously until the TPC history is finished, the ACK is returned to the minimum transmission power value. Fix (S1811). Even if it is lowered until the TPC history is completed, if ACK is returned continuously, the target transmission power value is even smaller. Therefore, the TPC history cannot be handled, and the process proceeds to step S1813 to perform normal TPC again. At that time, the TPC history is saved (S1815).

(Effect of this embodiment)
As a result of the above processing, as shown in FIG. 20 and FIG. 21, whatever the relationship between the previous initial transmission power value and the target transmission power value is, what is the current target transmission power value? However, the TPC history can be used efficiently. In addition, the code | symbol which starts from S in FIG. 20, FIG. 21 respond | corresponds to the step described in the flowchart of FIG. 13, FIG. 16, FIG. 18 which determines each target transmission power value. That is, as shown in FIG. 20, when the current target transmission power value is smaller than the previous initial transmission power value, the target transmission power value can be determined in step S1317. If the current target transmission power value is larger than the previous initial transmission power value and smaller than the previous target transmission power value, the target transmission power value can be determined in step S1307. The current target transmission power value is larger than the previous target transmission power value, but if the difference is less than or equal to the difference between the previous initial transmission power value and the previous target transmission power value, the current target transmission power value is determined in step S1603. it can. If the current target transmission power value is greater than the previous target transmission power value and the difference is greater than or equal to the difference between the previous initial transmission power value and the previous target transmission power value, the target transmission power value can be determined in step S1611.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. In the second embodiment, the initial transmission power value is changed according to the situation, but in the third embodiment, the previous target transmission power value is always the initial transmission power value. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the process of FIG. 22 is performed instead of the process of FIG. First, in step S2201, the previous target value is uniformly set as the initial transmission power value. Next, in S2202, the previous target value is compared with the previous initial transmission power value. If the previous target value is larger than the previous initial transmission power value, the process proceeds to step S2225. If ACK is returned continuously, the process proceeds to step S1307 in FIG. 13 and the processes of S1307 to S1313, S1317, and S1319 are performed. . If ACK is not returned continuously in S2225, the process proceeds to S1603 in FIG.

  On the other hand, as shown in FIG. 23, when the previous target transmission power value is less than or equal to the previous initial transmission power value, the process proceeds from step S2202 to S2203. In this case, in step S2203, it is determined whether or not ACK is returned continuously. If ACK is returned continuously, the current target transmission power value is lower than the previous target transmission power value. use. If there is no continuous ACK reply until the TPC history is completed (S2207), the process proceeds to step S2211, and is fixed to the minimum transmission power value at which ACK is returned continuously.

  Next, if it is determined in step S2201 that ACKs are not returned continuously, the process proceeds to step S2217, and the TPC history is used in reverse order. That is, in this case, since the current target transmission power value is larger than the previous target transmission power value, control for increasing the transmission power value is performed. Thereafter, if there is a continuous ACK reply until the TPC history ends (S2219), the process proceeds from step S2221 to S2223, and is fixed to the transmission power value. On the other hand, if all TPC histories are used before the target transmission power value is found in steps S2207 and S2219, the process proceeds to step S2213, and TPC is performed as usual using SRS or the like. At this time, the TPC history is newly saved (S2215).

In summary, in this embodiment, processing is performed as follows.
・ When deviating from the previous power transition range → Use the TPC history as it is ・ When transitioning within the previous power transition range → Use the TPC history in reverse order The direction of transition and the usage of the TPC history are consistent, and the expected transmission power can be reached.

(Effect of this embodiment)
As a result of the above processing, as shown in FIG. 23, when the previous initial transmission power value is higher than the previous target transmission power value and the current target transmission power value is smaller than the previous target transmission power value. The TPC history can be used more efficiently. That is, when the current target transmission power value is larger than the previous initial transmission power value, the target transmission power value can be determined in step S2213. When the current target transmission power value is smaller than the previous initial transmission power value and larger than the previous target transmission power value, the target transmission power value can be determined in step S2223. Although the current target transmission power value is smaller than the previous target transmission power value, if the difference is less than or equal to the difference between the previous initial transmission power value and the previous target transmission power value, the target transmission power value can be determined in step S2211. . If the current target transmission power value is smaller than the previous target transmission power value and the difference is greater than or equal to the difference between the previous initial transmission power value and the previous target transmission power value, the target transmission power value can be determined in step S2213.

<Other embodiments>
As mentioned above, although embodiment of this invention was explained in full detail, the same operation | movement is possible also in a femtocell besides the said embodiment. Since the femtocell has a smaller cell radius than the above macrocell and microcell, there is little change in radio characteristics depending on the location. Therefore, it is considered that there is little change in TPC performed each time a link is established, and it is considered that a method using a TPC history can function more effectively than a macro cell.

  In the above embodiment, the case where the mobile station 101 moves to another cell and returns to the cell 103 has been described. However, the present invention is not limited to this, and once the mobile station is powered off. This is also applicable when the power is turned on again.

  Further, the present invention may be applied to a system composed of a plurality of devices, or may be applied to a single device. Furthermore, the present invention can also be applied to a case where a transmission power control program that realizes the functions of the embodiments is directly or remotely supplied to a system or apparatus and executed. As the transmission power control program, there are those represented by the flowcharts of FIGS. 7 and 8, those represented by the flowcharts of FIGS. 13, 16, and 18, and those represented by the flowchart of FIG. Therefore, in order to realize the functions of the present invention on a computer, a program installed in the computer, a medium storing the program, and a WWW server that downloads the program are also included in the scope of the present invention.

In addition, based on the description in the above embodiment, the base station described in Appendix 1 below can also be included in the category of the present invention.
(Appendix 1)
A base station that performs radio communication with a mobile station in a cell, a means for transmitting a transmission power control command to the mobile station, and a history of transmission power control in the mobile station, the mobile station And means for scheduling the transmission power control command as having been transmitted to the mobile station in accordance with the transmission power control history received from the mobile station. Base station.

Claims (10)

A transmission power control method for a cellular system for performing wireless communication between a base station and a mobile station in a cell managed by the base station,
Transmitting a transmission power control command from the base station to the mobile station in the cell;
In the mobile station, a history of transmission power control performed according to the received transmission power control command is stored in association with the cell;
Determining whether the mobile station has returned to management of the base station again after being removed from management of the base station;
The transmission power control that was saved when the mobile station was under the management of the base station in the past when the mobile station was removed from the management of the base station and then returned to the management of the base station. Step of performing transmission power control using the history of
A transmission power control method for a cellular system. When the mobile station is removed from the management of the base station and then returns to the management of the base station, it is determined whether or not the mobile station is out of the management of the base station within a certain period in the past. And further comprising steps
The transmission power control is performed using the history of the transmission power control that has been stored when the timing that is out of management of the base station is within the predetermined period. A transmission power control method for a cellular system.   The transmission power control that was saved when the mobile station was under the management of the base station in the past when the mobile station was removed from the management of the base station and then returned to the management of the base station. The transmission power control method for a cellular system according to claim 1, further comprising a step of transmitting the history of the transmission to the base station.   After the mobile station is removed from the management of the base station, when the mobile station returns to the management of the base station again, the base station does not wait for reception of a transmission power control command from the base station in the past. The transmission power control of the cellular system according to claim 1, 2 or 3, further comprising: a step of transmitting the transmission power control history stored when being under the management of the base station to the base station. Method. The mobile station stores a history of transmission power control corresponding to the transmission power control command for n times,
If normal data communication cannot be established even if transmission power control is performed using the history of transmission power control for n times stored when the base station was under management in the past, The transmission power control method for a cellular system according to any one of claims 1 to 4, wherein transmission power control is performed using a transmission power control command newly transmitted from a base station.   The mobile station selectively selects one of the last transmission power value of the previous transmission power control and the initial transmission power value of the previous transmission power control, which is left in the history of the transmission power control, as the initial transmission power. The transmission power control method for a cellular system according to any one of claims 1 to 5, wherein the transmission power control method is used as a value.   The mobile station performs transmission power control using the history of transmission power control while always using the final transmission power value of the previous transmission power control, which is left in the history of transmission power control, as the initial transmission power value. The transmission power control method for a cellular system according to any one of claims 1 to 6.   The transmission power control method for a cellular system according to any one of claims 1 to 7, wherein the transmission power control is performed using the history of the transmission power control in reverse order of time series. A mobile station that performs radio communication with the base station in a cell managed by the base station,
Means for receiving a transmission power control command from the base station;
Means for storing a history of transmission power control performed in response to the received transmission power control command in association with the cell;
After the mobile station is removed from the management of the base station, when the mobile station returns to the management of the base station again, the transmission power control stored when the mobile station was under the management of the base station in the past. Means for performing transmission power control using history;
A mobile station characterized by comprising: A transmission power control program executed by a mobile station that performs radio communication with the base station in a cell managed by the base station,
In the processor provided in the mobile station,
A function of receiving a transmission power control command from the base station;
A function of storing a history of transmission power control performed according to the received transmission power control command in association with the cell;
A function of determining whether the mobile station has returned to the management of the base station again after being removed from the management of the base station;
The transmission power control that was saved when the mobile station was under the management of the base station in the past when the mobile station was removed from the management of the base station and then returned to the management of the base station. A function to perform transmission power control using the history of
The transmission power control program characterized by performing this.

Images