JP2006287489A - Mobile communications system and method of controlling downlink initial transmission power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten an initial transmission power control section until establishment of downlink wireless synchronization when propagation conditions are good. <P>SOLUTION: A BTS 102 sends the number of times of ramping reported from an MS101 to an RNC103 to obtain the propagation condition and an initial transmission power value which the MS101 uses at the time of synchronization. When the obtained propagation condition is satisfactory, a part or all of the number of times of increase, an increase width and an increase period being parameters for control for gradually increasing the transmission power value of the MS101 to reach the initial transmission power value, are set to be a little smaller so as to raise the transmission starting power value of the MS101. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mobile communication system and a downlink initial transmission power control method.

  FIG. 11 is a block diagram illustrating a configuration example of a conventional mobile communication system. In addition, in FIG. 11, the structure mainly related to downlink initial transmission power control is shown. A mobile communication system 1100 shown in FIG. 11 includes a mobile station (MS) 1101, a radio base station apparatus (BTS) 1102 to which the mobile station (MS) 1101 is wirelessly connected in each cell or sector, and each BTS 1101 is connected by wire. A base station controller (RNC) 1103 that is a higher-level device.

  A mobile station (MS) 1101 includes a radio unit 1112 to which an antenna 1111 is connected, a RACH (random access channel) transmission unit 1113, a BCH (broadcast channel) reception unit 1114, and a reception SIR (desired wave to interference wave ratio). And a calculation unit 1115.

  Radio section 1112 down-converts the downlink radio signal in the gigahertz band received by antenna 1111 to a baseband signal, extracts information (baseband IQ signal) carried on the carrier wave, and provides it to BCH reception section 1114. The BCH receiving unit 1114 despreads and demodulates the BCH, which is a downlink common channel included in the baseband IQ signal received from the radio unit 1112, and provides the received SIR calculating unit 1115 with it.

  Reception SIR calculation section 1115 calculates the SIR value as the BCH reception intensity, and provides it to RACH transmission section 1113. The RACH transmission unit 1113 inserts the reception SIR value received from the reception SIR calculation unit 1115 into the RACH that is an uplink common channel, modulates and spreads the RACH, and provides the radio unit 1112 as a baseband IQ signal. The radio unit 1112 up-converts the carrier wave carrying the baseband IQ signal received from the RACH transmission unit 1113 into a gigahertz-band radio signal, excites the antenna 1111 and transmits it to the uplink.

  Also, the radio base station apparatus (BTS) 1102 includes a radio unit 1122 to which an antenna 1121 is connected, a RACH reception unit 1123, a RACH decoding unit 1124, a BCH transmission unit 1125, and a DPCH (downlink dedicated channel) encoding unit 1126. And a DPCH transmission unit 1127.

  The radio unit 1122 down-converts the gigahertz uplink radio signal received by the antenna 1121 into a baseband signal, extracts information (baseband IQ signal) carried on the carrier wave, and provides the RACH receiver 1123 with the information. The RACH receiving unit 1123 despreads and demodulates the RACH that is an uplink common channel included in the baseband IQ signal received from the radio unit 1122, and provides the RACH decoding unit 1124 with the RACH. The RACH decoding unit 1124 decodes the RACH signal received from the RACH receiving unit 1123 and transmits the decoded signal to the base station controller (RNC) 1103 via the wired transmission path 1104.

  The BCH transmission unit 1125 modulates and spreads the BCH received from the base station controller (RNC) 1103 via the wired transmission path 1104, and provides the radio unit 1122 with the baseband IQ signal. The radio unit 1122 up-converts the carrier wave carrying the baseband IQ signal received from the BCH transmission unit 1125 into a gigahertz band radio signal, excites the antenna 1121, and transmits it to the downlink.

  The DPCH encoding unit 1126 encodes the DPCH received from the base station controller (RNC) 1103 via the wired transmission path 1104 and supplies the encoded DPCH to the DPCH transmission unit 1127. The DPCH transmission unit 1127 modulates and spreads the encoded DPCH received from the DPCH encoding unit 1126, and provides the radio unit 1122 with the baseband IQ signal. The radio unit 1122 up-converts the carrier wave carrying the baseband IQ signal received from the DPCH transmission unit 1127 into a gigahertz band radio signal, excites the antenna 1121, and transmits it to the downlink.

  The base station controller (RNC) 1103 includes an MS reception SIR detection unit 1131, a propagation status determination unit 1132, a DPCH initial transmission power value determination unit 1133, and a call control data transmission unit 1134.

  The MS reception SIR detection unit 1131 extracts the reception SIR value from the information received from the RACH decoding unit 1124 and provides it to the propagation state determination unit 1132. The propagation status determination unit 1132 determines the propagation status from the received SIR value received from the MS reception SIR detection unit 1131, gives the determination result to the DPCH initial transmission power value determination unit 1133, and transmits the determination result to the wireless base station via the wired transmission path 1104. The data is sent to the station apparatus (BTS) 1102. The DPCH initial transmission power value determination unit 1133 determines an initial transmission power value based on the propagation status determined by the propagation status determination unit 1132, and sends the initial transmission power value to the radio base station apparatus (BTS) 1102 via the wired transmission path 1104. On the other hand, the call control data transmission unit 1134 realizes wired transmission of call control data such as call information between the radio base station apparatus (BTS) 1102 and the exchange.

  Next, a conventional downlink initial transmission power control method will be described with reference to FIG. 11 and FIG. FIG. 12 is a diagram for explaining a conventional downlink initial transmission power control procedure. When a connection request is input from the user, the MS 1101 performs a downlink radio link establishment operation by cell search. When the downlink radio link is established, the MS 1101 then executes random access control to the uplink radio link using RACH at the start of communication in order to establish an uplink radio link with the BTS 1102.

  This random access control is executed in the following procedure. [Procedure 1] The RACH is composed of one or more preamble parts and a message part that follows the RACH, but the MS 1101 first transmits the RACH of only the preamble part. [Procedure 2] When the reception of the preamble part can be detected, the BTS 1102 transmits an AICH (synchronization detection display channel) indicating that the preamble part has been detected. [Procedure 3] When the MS 1101 can receive the AICH, the BTS 1102 determines that the spreading code and the reception timing of the message part can be detected, and transmits the RACH including the message part into which the received SIR value is inserted. The above is a case where the propagation situation is good.

  If the propagation condition is bad, the MS 1101 may not be able to receive the AICH in the procedure 3. Further, even if the BTS 1102 cannot receive the preamble part and does not transmit the AICH in the procedure 2, the MS 1101 cannot receive the AICH. [Procedure 4] The MS 1101 repeats retransmitting the RACH of only the preamble part shown in Procedure 1 until the AICH can be received. When the MS 1101 can receive the AICH, it executes [Procedure 3].

  In the RACH retransmission operation of only the preamble part in this procedure 4, until the AICH can be received, the MS 1101 increases the transmission power at the previous transmission power a plurality of times (number of ramping times) by the power ramping step width. Send repeatedly. Note that the power ramping width and the number of ramping are parameters predetermined in the MS 1101.

  The section where the random access control according to the procedure 1 to the procedure 4 described above is performed is an untransmitted section 1201 shown in FIG. When the BTS 1102 receives the RACH including the message part from the MS 1101, the BTS 1102 starts the initial transmission power control.

  That is, the BTS 1102 decodes the received SIR value included in the message part from the MS 1101 and notifies the RNC 1103 of it. The RNC 1103 determines the radio propagation status between the MS 1101 and the BTS 1102 based on the received SIR value from the MS 1101, and determines the downlink initial transmission power value (variation value). The RNC 1103 determines the downlink initial transmission power value from the viewpoint of establishing downlink radio synchronization with as low power as possible if the downlink initial transmission power value is high, which causes interference with other MSs.

  The BTS 1102 calculates a downlink initial transmission start power value using a predetermined increase number (fixed value) and an increase width (fixed value) based on the downlink initial transmission power value (variation value) determined by the RNC 1103, Send to MS1101. After transmitting the downlink initial transmission start power value, the BTS 1102 uses the increase count (fixed value), the increase width (fixed value), and the increase cycle (fixed value) of the MS 1101 until the downlink initial transmission power value is reached. Repeat the control to increase the transmission power.

  The above is the operation in the initial transmission power control section 1202 shown in FIG. If the downlink initial transmission power value determined by the RNC 1103 is transmitted as the downlink initial transmission start power value, it is assumed that radio synchronization can be established in the vicinity of the determined downlink initial transmission power value. Conventionally, as shown in FIG. At the start of transmission, control is performed with a somewhat lower power value, and control for gradually increasing the transmission power is performed.

As shown in FIG. 12, when the propagation environment is bad, both the initial downlink transmission power value and the transmission start power value are set higher in order to make the MS 1101 easier to receive. On the other hand, when the propagation environment is good, both the initial downlink transmission power value and the transmission start power value are set lower. This is because the MS 1101 can receive the signal even if the power is lowered because the propagation state is good. The initial transmission power control section is a fixed period in any case. This is a measure for reflecting the change in the downlink initial transmission power in the downlink transmission start power value.
International Publication No. 98/048528 Pamphlet

  In the conventional downlink initial transmission power control method, even when the propagation condition is good, the initial transmission power control period requires the same control period as when the propagation condition is bad, so that it takes a long time to establish downlink radio synchronization. There's a problem.

  The present invention has been made in view of the above points, and when the propagation condition is good, the mobile communication system and the downlink initial transmission power control capable of shortening the initial transmission power control period until the downlink radio synchronization is established. It aims to provide a method.

  In order to solve such a problem, a mobile communication system according to the present invention is a mobile communication system that performs downlink initial transmission power control in a period until synchronization is established between a mobile station that has performed cell search and a radio base station. The wireless base station wire-transmits information about the propagation environment inserted by the mobile station included in the wirelessly received random access channel to a higher-level control device, and the propagation status and initial transmission power used when the mobile station establishes synchronization. Means for acquiring a value, means for determining each value of the number of increases, an increase width, and an increase period, which are initial transmission power control parameters based on the acquired propagation status, and the initial transmission power value determined as the acquired initial transmission power value The means for determining the transmission start power value of the mobile station based on each value of the transmission power control parameter and the downlink dedicated channel, A means for wirelessly transmitting a transmission start power value, and thereafter, gradually increasing the transmission power value of the mobile station based on each value of the initial transmission power control parameter and controlling to reach the initial transmission power value Take.

  Further, the downlink initial transmission power control method according to the present invention is a mobile communication system that performs downlink initial transmission power control in a period until synchronization can be established between a mobile station that has performed cell search and a radio base station. The radio base station wire-transmits information about the propagation environment inserted by the mobile station included in the wirelessly received random access channel to a higher-level control device, and determines the propagation status and the initial transmission power value used by the mobile station when establishing synchronization. A step of acquiring, a step of determining each value of an increase number, an increase width, and an increase period, which are initial transmission power control parameters based on the acquired propagation state, and the initial transmission power value determined as the acquired initial transmission power value Determining a transmission start power value of the mobile station based on each value of the control parameter, and using the downlink dedicated channel, first, the transmission start power value The value transmitted by radio and then to and a step of controlling so that the gradually increasing the initial transmission power value of the mobile station based on each value of the transmission power control parameter reaches the initial transmission power value.

  According to the present invention, when the propagation condition is good, the initial transmission power control period until the downlink radio synchronization is established can be shortened, so that the time until the downlink radio synchronization is established can be shortened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a mobile communication system according to Embodiment 1 of the present invention. In FIG. 1, components that are the same as or equivalent to the components shown in FIG. 11 (conventional example) are given the same reference numerals. Here, the description will be focused on the portion related to the first embodiment.

  As shown in FIG. 1, a mobile communication system 100 according to Embodiment 1 includes a mobile station (MS) 101, a radio base station apparatus (BTS) 102, and a base station control apparatus (RNC) 103. Yes.

  In the mobile station (MS) 101, in the mobile station (MS) 1101 shown in FIG. 11 (conventional example), instead of the BCH reception unit 1114 and the reception SIR calculation unit 1115, an AICH reception unit 111, a random access determination unit 112, A ramping frequency notification unit 113 is provided.

  The AICH receiving unit 111 despreads and demodulates the AICH, which is a downlink common channel included in the baseband IQ signal received from the radio unit 1112, and provides the random access determining unit 112 with it. When the random access determination unit 112 receives the AICH from the AICH reception unit 111, the random access determination unit 112 stops the RACH transmission of only the preamble part in the RACH transmission unit 1113 and starts transmission of the RACH including the message. The ramping frequency notification unit 113 outputs the ramping frequency to be notified to the radio base station apparatus (BTS) 102 to the RACH transmission unit 1113 when the random access determination unit 112 determines AICH reception. The RACH transmission unit 1113 transmits the RACH including the number of times of ramping in the message.

  Further, in the radio base station apparatus (BTS) 102, an AICH transmission section 121 is provided in place of the BCH transmission section 1125 in the radio base station apparatus (BTS) 1102 shown in FIG. A value determining unit 122 is added.

  When the AICH transmission unit 121 receives the preamble from the RACH reception unit 1123, the AICH transmission unit 121 modulates and spreads the AICH that is the uplink common channel, and provides the radio unit 1122 with the baseband IQ signal. Based on the initial transmission power value and the propagation status received from the base station controller (RNC) 103 via the wired transmission line 1104, the transmission start power value determination unit 122 increases the transmission start power value and the initial transmission power control parameter (increase). Frequency, increase width, increase cycle) and determine the determined transmission start power value to the DPCH transmitter 1127.

  Further, in the base station controller (RNC) 103, a ramping frequency receiver 131 is provided in place of the MS reception SIR detector 1131 in the base station controller (RNC) 1103 shown in FIG. 11 (conventional example). Yes. Further, a propagation status determination unit 132 is provided instead of the propagation status determination unit 1132.

  The ramping frequency reception unit 131 extracts the ramping frequency from the information received from the RACH decoding unit 1124 via the wired transmission path 1104 and supplies the ramping frequency reception unit 131 to the propagation status determination unit 132. The propagation status determination unit 132 determines the propagation status from the number of ramping received from the ramping number reception unit 131, gives the determination result to the DPCH initial transmission power value determination unit 1133, and also the radio base station apparatus via the wired transmission path 1104 It is sent to the transmission start power value determination unit 122 of the (BTS) 102.

  Next, the downlink initial transmission power control method according to the first embodiment will be described with reference to FIGS. FIG. 2 is a flowchart for explaining a random access control operation performed by the mobile station shown in FIG. 1 at the start of communication. FIG. 3 is a flowchart for explaining the RACH reception operation of the radio base station apparatus shown in FIG. FIG. 4 is a diagram illustrating an example of an operation in which the base station control device illustrated in FIG. 1 determines an initial transmission power value according to a propagation state based on the RACH received by the radio base station device illustrated in FIG. FIG. 5 is a flowchart for explaining an initial transmission power control operation using a downlink dedicated channel performed by the radio base station apparatus shown in FIG. FIG. 6 is a diagram illustrating an example of an operation in which the radio base station apparatus illustrated in FIG. 1 increases or decreases the transmission start power value according to the propagation state. FIG. 7 is a diagram for explaining a downlink initial transmission power control procedure performed in the mobile communication system shown in FIG. Here, in the description of FIG. 2, FIG. 3, and FIG. 5, the step indicating the procedure is abbreviated as “ST”.

  In FIG. 2, when the MS 101 completes the cell search (ST201: Yes), the RACH transmission unit 1113 wirelessly transmits the RACH including only the preamble portion (ST202), and the random access determination unit 112 checks whether or not the AICH has been successfully received (ST202). ST203). If the AICH cannot be received (ST203: No), the random access determination unit 112 performs power ramping to increase the RACH transmission power value of only the preamble unit (ST204), and the ramping count notification unit 113 increments the ramping count. (ST205), RACH transmission section 1113 again wirelessly transmits the RACH of only the preamble section (ST202), and random access determination section 112 checks whether AICH has been successfully received (ST203).

  ST202 → ST203: No → ST204 → ST205 → When the AICH can be received as a result of the repetition operation (ST203: Yes), the random access determination unit 112 stops the RACH transmission unit 1113 from transmitting the RACH of only the preamble part. The ramping frequency notification unit 113 obtains the ramping frequency (ST206), and wirelessly transmits the RACH inserted in the message unit (ST207).

  In FIG. 3, the BTS 102 monitors whether or not the RACH is received only by the preamble part (ST301), and when it can receive the RACH only by the preamble part (ST301: Yes), wirelessly transmits the AICH (ST302). Next, when the RACH including the message part is received (ST303), the RACH is decoded and wired to the RNC 103 (ST304).

  In RNC 103, in FIG. 1, the ramping number reception unit 131 extracts the ramping number from the decoded data, the propagation state determination unit 132 determines the quality of the propagation state based on the number of ramping, and the DPCH initial transmission power value determination unit 1133 enters the propagation state. The dependent initial transmission power value is determined (see FIG. 4). The determined propagation status and the determined initial transmission power value are wired to the transmission start power value determination unit 122 of the BTS 102.

  FIG. 4 shows an example of the relationship between the “ramping count”, the “propagation status” to be determined, and the “initial transmission power value” to be determined. For example, as shown in FIG. 4, when the number of ramping times = 1, the propagation state is determined to be quite good, and the initial transmission power value is determined to be a value that is reduced by 6 dB as compared with the case where the propagation state is bad. When the number of ramping times = 2, it is determined that the propagation state is good, and the initial transmission power value is determined to be a value that is 3 dB lower than the case where the propagation state is bad. Further, when the number of ramping times = 3, the propagation state is determined to be normal, and the initial transmission power value is determined to be 1 dB lower than the conventional example. When the number of ramping times is 4 or more, it is determined that the propagation state is bad, and the initial transmission power value is determined to be a value of ± 0 dB.

  In the BTS 102, initial transmission power control is executed according to the procedure shown in FIG. In FIG. 5, the transmission start power value determination unit 122 of the BTS 102 obtains the propagation status (pretty good, good, normal, bad) and the initial transmission power control parameters (increase number, increase width, increase period) from the RNC 103 ( ST501, ST502), the value of the initial transmission power control parameters (increase number of times, increase width, increase period) depending on the propagation situation (pretty good, good, normal, bad) determined by the RNC 103 is determined as shown in FIG. (ST503).

  Then, transmission start power value determination section 122 applies the values of the initial transmission power control parameters (increase count, increase width, increase cycle) determined in ST503 to the initial transmission power value (ST504) acquired from RNC 103. For example, as shown in FIG. 6, a transmission start power value depending on the propagation state (pretty good, good, normal, bad) determined by the RNC 103 is calculated (ST505).

  FIG. 6 shows an example of the relationship between the propagation status (substantially good, good, normal, bad) determined by the RNC 103 and the number of increases (transmission start power) determined by the transmission start power value determination unit 122. In FIG. 6, the increase width is 1 dB. As illustrated in FIG. 6, when the propagation state is “substantially good”, for example, it is determined that the number of increases is decreased by 6 times, and the transmission start power is increased by 6 dB. When the propagation state is “good”, it is determined that the number of increases is decreased by 3 times, and the transmission start power is increased by 3 dB. When the propagation state is “normal”, the number of increases is determined to be decreased once, and the transmission start power is calculated to be increased by 1 dB. When the propagation status is “bad”, the number of increases and the transmission start power are determined to be the same value (± 0 dB) as in the conventional example.

  Returning to FIG. 5, the transmission start power value calculated by the transmission start power value determination unit 122 as described above is put on the DPCH which is the downlink dedicated channel by the DPCH transmission unit 1127 and wirelessly transmitted to the MS 101. Transmission power control is started (ST506).

  In the downlink initial transmission power control, the transmission power of the MS 101 is repeatedly increased until the transmission power value of the MS 101 reaches the initial transmission power value using the determined number of increases, increase width, and increase period ( ST507 → ST508: No → ST507). When the transmission power value of MS 101 reaches the initial transmission power value (ST508: Yes), the process proceeds to the process of establishing wireless synchronization. The downlink initial transmission power control in this embodiment is as shown in FIG.

  As shown in FIG. 7, when the propagation environment is good, the initial transmission power value is lowered by the value (a) as in the conventional example (FIG. 12), but the transmission start power value is the same as in the conventional example (FIG. 12). ) And the initial transmission power control section 702 is shorter by the section (c) than the conventional example (FIG. 12).

  As described above, according to the first embodiment, not only the initial transmission power value is increased / decreased depending on the propagation state, but also the power increase method by the initial transmission power control is changed, so that it can be determined that the propagation state is good. In some cases, the initial transmission power control period can be shortened. As a result, it is possible to shorten the time until establishment of downlink radio synchronization, and a smooth mobile communication service can be realized.

(Embodiment 2)
FIG. 8 is a block diagram showing the configuration of the mobile communication system according to Embodiment 2 of the present invention. In FIG. 8, components that are the same as or equivalent to the components shown in FIG. 11 (conventional example) and FIG. 1 (Embodiment 1) are assigned the same reference numerals. Here, the description will be focused on the portion related to the second embodiment.

  As shown in FIG. 8, mobile communication system 800 according to Embodiment 2 includes mobile station (MS) 801, radio base station apparatus (BTS) 802, and base station controller (RNC) 803. Yes.

  The mobile station (MS) 801 has the same configuration as the mobile station (MS) 1101 shown in FIG. 11 (conventional example). In the radio base station apparatus (BTS) 802, the transmission start power value determining unit 122 shown in FIG. 1 is added to the radio base station apparatus (BTS) 1102 shown in FIG. 11 (conventional example). In the base station controller (RNC) 803, in the base station controller (RNC) 1103 shown in FIG. 11 (conventional example), a propagation state determination unit 831 is provided instead of the propagation state determination unit 1132, and a reference SIR holding unit 832 has been added.

  The reference SIR holding unit 832 holds an SIR value that serves as a reference for the propagation status determination unit 831 to compare the received SIR value from the MS reception SIR detection unit 1131 and determine the propagation status.

  Next, the downlink initial transmission power control method according to the second embodiment will be described with reference to FIGS. FIG. 9 is a diagram for explaining an example of an operation in which the base station control device shown in FIG. 8 determines an initial transmission power value corresponding to the propagation state based on the RACH received by the radio base station device shown in FIG. . FIG. 10 is a diagram illustrating an example of an operation in which the radio base station apparatus illustrated in FIG. 8 increases or decreases the transmission start power value according to the propagation state.

  When the MS 801 can receive the AICH from the BTS 802, the MS 801 wirelessly transmits the RACH on which the measured reception SIR value of the BCH is placed. The BTS 802 decodes the wirelessly received RACH information and wire-transmits it to the RNC 803.

  In RNC 803, MS reception SIR detection section 1131 detects the reception SIR value from the decoded data. The propagation state determination unit 831 determines the propagation state by comparing the reception SIR value from the MS reception SIR detection unit 1131 with the reference SIR value held by the reference SIR holding unit 832. The DPCH initial transmission power value determination unit 1133 determines an initial transmission power value according to the propagation status determined by the propagation status determination unit 831 and performs wired transmission to the transmission start power value determination unit 122 of the BTS 802.

  FIG. 9 shows a relationship example between the “BCH reception SIR value”, the “propagation state” to be determined, and the “initial transmission power value” to be determined. For example, as shown in FIG. 9, when the received SIR value is 2 dB or more higher than the reference SIR value, the propagation state is determined to be “pretty good”, and the initial transmission power value is reduced by 6 dB compared to the case where the propagation state is bad. The value is determined. When the received SIR value is 1 dB or more higher than the reference SIR value, the propagation state is determined as “good”, and the initial transmission power value is determined to be a value that is 3 dB lower than that in the case where the propagation state is bad. When the received SIR value is less than 1 dB with respect to the reference SIR value, the propagation state is determined to be “normal”, and the initial transmission power value is determined to be a value that is reduced by 1 dB as compared with the case where the propagation state is bad. When the received SIR value is less than 0.5 dB with respect to the reference SIR value, the propagation state is determined as “bad”, and the initial transmission power value is determined to be ± 0 dB.

  When the transmission start power value determination unit 122 of the BTS 802 acquires the propagation status (pretty good, good, normal, bad) and the initial transmission power value from the RNC 803, the initial value depending on the propagation status (pretty good, good, normal, bad) The values of the transmission power control parameters (increase frequency, increase width, increase cycle) are determined as shown in FIG. 10, for example.

  FIG. 10 shows an example of the relationship between the propagation status (substantially good, good, normal, and bad) determined by the RNC 803 and the number of increases (transmission start power) determined by the transmission start power value determining unit 122. In FIG. 10, the increase width is 1 dB. As illustrated in FIG. 10, when the propagation state is “substantially good”, for example, it is determined that the number of increases is decreased by 6 times, and the transmission start power is increased by 6 dB. When the propagation state is “good”, it is determined that the number of increases is decreased by 3 times, and the transmission start power is increased by 3 dB. When the propagation state is “normal”, the number of increases is determined to be decreased once, and the transmission start power is calculated to be increased by 1 dB. When the propagation status is “bad”, the number of increases and the transmission start power are determined to be the same value (± 0 dB) as in the conventional example.

  The transmission start power value calculated by the transmission start power value determining unit 122 as described above is put on the DPCH which is the downlink dedicated channel by the DPCH transmission unit 1127 and wirelessly transmitted to the MS 801, and downlink initial transmission power control is started. The

  As described above, according to the second embodiment, as in the first embodiment, not only the initial transmission power value is increased / decreased depending on the propagation situation, but also the power increase method by the initial transmission power control is changed. When it can be determined that the propagation state is good, the initial transmission power control section can be shortened. As a result, it is possible to shorten the time until establishment of downlink radio synchronization, and a smooth mobile communication service can be realized.

  In the first embodiment, the propagation state is determined by using the number of ramping times and in the second embodiment using the comparison result between the received SIR value and the reference SIR. The reception intensity SIR of the RACH may be measured, the propagation state may be determined using the reception SIR value, and reflected in the downlink initial transmission power control.

  The present invention is useful for shortening the initial transmission power control interval when the propagation state is good.

Block diagram showing the configuration of the mobile communication system according to the first embodiment of the present invention. The flowchart explaining the random access control operation which the mobile station shown in FIG. The flowchart explaining the RACH receiving operation of the radio base station apparatus shown in FIG. The figure explaining an example of the operation | movement which the base station control apparatus shown in FIG. 1 determines the initial transmission power value according to a propagation condition based on RACH which the wireless base station apparatus shown in FIG. 1 received The flowchart explaining the initial transmission power control operation using the downlink dedicated channel performed by the radio base station apparatus shown in FIG. The figure explaining an example of the operation | movement which the radio base station apparatus shown in FIG. 1 increases / decreases transmission start power value according to a propagation condition The figure explaining the downlink initial transmission power control procedure implemented in the mobile communication system shown in FIG. Block diagram showing the configuration of a mobile communication system according to Embodiment 2 of the present invention. The figure explaining an example of the operation | movement which the base station control apparatus shown in FIG. 8 determines the initial transmission power value according to a propagation condition based on RACH which the wireless base station apparatus shown in FIG. 8 received. The figure explaining an example of the operation | movement which the radio base station apparatus shown in FIG. 8 increases / decreases transmission start power value according to a propagation condition Block diagram showing a configuration example of a conventional mobile communication system The figure explaining the downlink initial transmission power control procedure implemented in the conventional mobile communication system shown in FIG.

Explanation of symbols

100, 800 Mobile communication system 101, 801 Mobile station (MS)
102, 802 Wireless base station equipment (BTS)
103, 803 Base station controller (RNC)
111 AICH reception unit 112 Random access determination unit 113 Ramping count notification unit 121 AICH transmission unit 122 Transmission start power value determination unit 131 Ramping count reception unit 132, 831 Propagation status determination unit 832 Reference SIR holding unit 1111, 1121 Antenna 1112, 1122 Radio Unit 1113 RACH transmission unit 1123 RACH reception unit 1124 RACH decoding unit 1125 BCH transmission unit 1126 DPCH encoding unit 1127 DPCH transmission unit 1131 MS reception SIR detection unit 1133 DPCH initial transmission power value determination unit 1134 call control data transmission unit

Claims (5)

  In a mobile communication system that performs downlink initial transmission power control in a period until synchronization can be established between a mobile station that has performed cell search and a radio base station, the radio base station is included in a radio-received random access channel Means for wired transmission of information related to the propagation environment inserted by the mobile station to a higher-level control device to acquire a propagation status and an initial transmission power value used when the mobile station establishes synchronization, and initial transmission based on the acquired propagation status Start of transmission of the mobile station based on means for determining each value of increase number, increase width and increase period as power control parameters, and the obtained initial transmission power value and each value of the determined initial transmission power control parameter First, the transmission start power value is wirelessly transmitted using means for determining a power value and a downlink dedicated channel, and then the initial transmission power control Mobile communication system, characterized by comprising means for controlling so as to gradually increase the transmission power value of the mobile station based on each value of the parameter reaches the initial transmission power value.   The radio base station sets a part or all of the increase count, the increase range, and the increase period so that the transmission start power value becomes higher as the acquired propagation state is better. The mobile communication system according to claim 1.   The information on the propagation environment notified by the mobile station is a number of times of ramping obtained by counting the number of times of power ramping performed until the synchronization detection display channel transmitted by the radio base station can be received. The mobile communication system according to claim 1 or 2.   The mobile communication system according to claim 1 or 2, wherein the information on the propagation environment notified by the mobile station is a reception intensity measured on a predetermined downlink common channel.   In a mobile communication system that performs downlink initial transmission power control in a period until synchronization can be established between a mobile station that has performed cell search and a radio base station, the radio base station is included in a radio-received random access channel Information regarding propagation environment inserted by the mobile station is wired to an upper control device to acquire a propagation status and an initial transmission power value used when the mobile station establishes synchronization, and initial transmission based on the acquired propagation status The mobile station starts transmission based on the step of determining each value of the number of increases, the increase width, and the increase cycle, which are power control parameters, and the acquired initial transmission power value and each value of the determined initial transmission power control parameter A step of determining a power value, and using the downlink dedicated channel, first, the transmission start power value is wirelessly transmitted, and then the initial transmission power control Downlink initial transmission power control method characterized by gradually increasing the transmission power value of the mobile station based on the values of parameters comprises the the steps of controlling so as to reach the initial transmission power value.

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