JP2007097055A - Transmitting/receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform open loop transmission power control with an optimal initial transmission power value by correcting a temporarily calculated initial transmission power value of a preamble part. <P>SOLUTION: Random access communication with a base station is started using an initial transmission power value calculated by a transmission power value calculation section 106. If the random access communication is not made successful, retransmission of a preamble part is repeated while gradually increasing the transmission power value. If made successful, a message part is transmitted using the transmission power value at that time. An initial transmission power correction value calculation section 108 calculates a correction value from a differential between the initial transmission power value and a transmission power value at the time of success. When starting random access communication of the next time, the transmission power value calculation section 106 defines a value adding the correction value to initial transmission power value calculated beforehand as an initial transmission power value of this time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmission / reception apparatus that is mounted in a mobile station of a mobile radio communication system and performs open loop transmission power control.

  A CDMA (Code Division Multiple Access) method, which is one of access methods in wireless communication, is an access method in which the same frequency and the same time are shared among users. In the CDMA system, a primary modulated signal is secondarily modulated by a spreading code and transmitted, and the receiving side extracts a target primary modulated wave by obtaining a correlation with a spreading code of a desired channel. In the process of despreading to obtain this correlation, the signal of the other channel becomes noise.

  In the downlink from the base station to the mobile station, the target signal wave and other interference waves are similarly subjected to fluctuations on the propagation path and reach each mobile station. The relationship between the reception level of the signal wave and the interference wave is constant. However, in the uplink from the mobile station to the base station, even if each mobile station transmits a signal wave with the same transmission power, the distance from the mobile station to the base station and the propagation environment are different. A so-called “far / near problem” occurs in which the wave reception level at the base station is different. Therefore, in order to correctly demodulate each signal wave by despreading in the base station, the reception level of each signal wave must be equal, so in the uplink from the mobile station to the base station, the state of each transmission path The transmission power control according to is required.

  Open loop transmission power control is one type of transmission power control, and is applied to a random access channel (RACH), which is a common channel, in the W-CDMA system. The random access channel includes a preamble part for starting random access communication between the mobile station and the base station, and a message part that carries communication data. That is, open-loop transmission power control in the W-CDMA system is performed using the preamble part. The outline will be described below.

  When starting a random access communication with a base station, the mobile station first transmits a preamble part to the base station with an initial transmission power value calculated based on information transmitted from the base station. The initial transmission power value is calculated by subtracting the measured reception level from the transmission power value of the reference channel transmitted by the base station to calculate the level of path loss (propagation loss in the radio section), and the base station does not consider the path loss. It is obtained by a unique calculation formula that adds the specified initial transmission power value and the amount of uplink interference.

  The base station notifies the mobile station of the presence or absence of reception of the preamble part using an AICH (Acquisition Indicator Channel) transmitted to the mobile station at a timing determined in advance with respect to the transmission timing of the preamble part. That is, when the base station can receive the preamble part, it transmits “ACK” indicating completion of reception of the preamble part on the AICH. On the other hand, if the base station has received the preamble part but does not accept the current random access, it transmits “NACK” on the AICH. Further, when the base station cannot receive the preamble part, the base station indicates “NG” by not transmitting any information on the presence / absence of reception of the preamble part on the AICH. Therefore, the case where the mobile station cannot receive “ACK” includes “NACK” and “NG”.

If the mobile station cannot receive “ACK” from the base station, the mobile station retransmits the preamble part with a transmission power value obtained by adding the power offset value ΔP0 designated by the base station to the transmission power value of the transmitted preamble part. . If the number of preamble part transmissions does not reach the maximum number of transmissions specified by the base station, the mobile station adds a power offset value ΔP0 until it can receive an ACK, and continues to retransmit the preamble part. That is, the mobile station performs a ramping operation in which the transmission power of the preamble part is gradually increased until ACK can be received. As a result, if “ACK” can be received from the base station, the random access communication is successful. When the mobile station can receive “ACK” from the base station, the mobile station uses a transmission power value obtained by adding the power offset value ΔPp-m designated by the base station to the transmission power value of the preamble part transmitted at this time. This time, send the message part.
3GPP TS25.331 8.5.7 Open loop power control

  However, in the open-loop transmission power control based on the initial transmission power value calculated by the unique calculation formula as described above, it is possible to determine what transmission power value actually reaches the base station with the calculated initial transmission power. In addition, there are variations in the received signal level measurement accuracy of the mobile station, transmission power variation of the transmitter, deviation from the optimum value due to temporal and environmental changes in the information for calculating transmission power broadcast from the base station, etc. The mobile station is not always able to transmit with the optimal transmission power value, and a case where a wasteful ramping operation is performed before the random access communication succeeds occurs.

  The present invention has been made in view of the above points, and enables transmission / reception capable of correcting the initial transmission power value of the preamble part calculated once and performing open loop transmission power control with a more optimal initial transmission power value. An object is to provide an apparatus.

  In order to solve such a problem, the transmission / reception apparatus according to the present invention is based on the difference between the transmission power value when the random access by the open loop transmission power control performed in the past is successful and the initial transmission power value calculated at that time. And a means for calculating a correction value for the initial transmission power value and a means for calculating an initial transmission power value used in the next open loop transmission power control based on the initial transmission power value and the correction value. .

  According to this configuration, the next open loop transmission power control is performed by adding a correction value obtained from the difference between the transmission power value when random access was successful in the past and the calculated initial transmission power value to the initial transmission power value. Therefore, open loop transmission power control can be performed with a more optimal initial transmission power value, and useless ramping operations can be reduced.

  According to the present invention, since the initial transmission power value of the preamble part calculated once can be corrected, it is possible to provide a transmission / reception apparatus capable of performing open loop transmission power control with a more optimal initial transmission power value. .

  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 transmission / reception apparatus according to an embodiment of the present invention. 1 includes a radio unit (RF unit) 102 that includes an antenna 101 and transmits and receives radio signals, a transmission power calculation information reception unit 103 that receives the reception output of the RF unit 102 in parallel, and a reception level measurement unit. 104 and the AICH receiving unit 105, the transmission power value calculation unit 106 that receives these outputs, and the RF unit 102 that receives the outputs of the AICH reception unit 105 and the transmission power value calculation unit 106, the preamble of the random access channel (RACH). A random access channel transmission unit (RACH transmission unit) 107 that outputs a part and a message part, a transmission power value calculation unit 106, and an initial transmission power correction value calculation unit 108 that exchanges signals are provided.

  FIG. 2 is a block diagram illustrating a configuration example of the initial transmission power correction value calculation unit illustrated in FIG. For example, as shown in FIG. 2, the initial transmission power correction value calculation unit 108 receives the output of the transmission power value calculation unit 106 in parallel, and the initial transmission power calculation value storage unit 201 and the successful transmission power value storage unit when the random access channel succeeds ( RACH success transmission power value storage unit) 202, subtraction unit 203 for obtaining a difference between these output values, gain unit 204 for multiplying the output of subtraction unit 203 by a predetermined gain, and the output of gain unit 204 are averaged An averaging unit 205 and a correction value generation unit 206 that obtains a correction value from the output value of the averaging unit 205 and outputs the correction value to the transmission power value calculation unit 106 are provided.

  Next, the open loop transmission power control operation will be described. A base station (not shown) transmits a broadcast channel, a reference channel, and AICH. The broadcast channel broadcasts information necessary for calculating the initial transmission power value of the random access channel in an open loop to each mobile station. The reference channel is used for reception level measurement at each mobile station. The AICH is used when the base station notifies the mobile station of whether or not the preamble part is received, and is transmitted to each mobile station at a timing determined in advance with respect to the transmission timing of the preamble part.

  That is, when the base station can receive the preamble part, it transmits “ACK” indicating completion of reception of the preamble part on the AICH. On the other hand, if the base station has received the preamble part but does not accept the current random access, it transmits “NACK” on the AICH. When the base station cannot receive the preamble part, the base station indicates “NG” by not transmitting any information on the presence / absence of reception of the preamble part on the AICH. Therefore, the case where the mobile station cannot receive “ACK” includes “NACK” and “NG”.

  The broadcast channel signal captured by the antenna 101 is converted into a baseband signal by the RF unit 102 and then input to the transmission power calculation information receiving unit 103. The transmission power calculation information receiving unit 103, from the received broadcast channel signal, the transmission power value Pbs of the reference channel necessary for obtaining the path loss, the initial transmission power value Pue designated by the base station not considering the path loss, The uplink interference amount Puli, the power offset value ΔP0 at the time of retransmission of the preamble part, and the power offset value ΔPp-m at the time of message part transmission are extracted and output to the transmission power value calculation unit 106.

  In parallel, the reference channel signal captured by the antenna 101 is converted into a baseband signal by the RF unit 102 and then input to the reception level measuring unit 104. The reception level measurement unit 104 measures the received signal level RSCP (Received Signal Code Power) of the reference channel and outputs it to the transmission power value calculation unit 106.

First, the transmission power value calculation unit 106 applies the transmission power value Pbs, the reception signal level RSCP, the initial transmission power value Pue, and the uplink interference amount Puli among the output values to the following equation (1), and the preamble. The initial transmission power value Ppreini of the part is calculated.
Ppreini = Pbs−RSCP + Puri + Pue (1)

  The calculated initial transmission power value Ppreini of the preamble part is input to the initial transmission power correction value calculation unit 108 and stored in the initial transmission power calculation value storage unit 201.

  In parallel, the calculated initial transmission power value Ppreini of the preamble part is given to the RF unit 102. In addition, transmission power value calculation section 106 notifies random access channel transmission section 107 that the preamble part initial transmission power value Ppreini has been calculated. In response to this, the random access channel transmission unit 107 generates a preamble part and gives it to the RF unit 102. As a result, the preamble part is transmitted from the RF unit 102 using the initial transmission power value Ppreini.

  AICH transmitted from the base station with a predetermined timing relationship with the preamble part transmission timing is input from the RF unit 102 to the AICH receiving unit 105. When the AICH receiving unit 105 can detect “ACK” and “NACK” included in the AICH, the AICH receiving unit 105 gives it to the transmission power value calculating unit 106 and the random access channel transmitting unit 107.

When the AICH receiving unit 105 can detect “ACK” and “NACK”, the transmission power value calculating unit 106 determines the power of transmission of the message part transmission extracted earlier and the initial transmission power value Ppreini of the preamble part calculated earlier. The offset value ΔPp−m is applied to the following equation (2) to calculate the power value Pmes for message part transmission.
Pmes = Ppreini + ΔPp−m (2)

  The calculated message part transmission power value Pmes is input to the initial transmission power correction value calculation unit 108 and stored in the RACH successful transmission power value storage unit 202.

  When the AICH receiving unit 105 can detect “ACK”, the calculated power value Pmes for message part transmission is given to the RF unit 102 in parallel. Also, the transmission power value calculation unit 106 notifies the random access channel transmission unit 107 of the completion of calculation of the power value Pmes for message part transmission. In response to this, the random access channel transmission unit 107 generates a message part and gives it to the RF unit 102. As a result, the message part is transmitted from the RF unit 102 using the power value Pmes. In addition, when the AICH receiving unit 105 can detect “NACK”, if the number of retransmissions does not reach the maximum number of transmissions designated by the base station, transmission of the preamble part with the initial transmission power value Ppreini starts after a predetermined time has elapsed. To do.

On the other hand, when the AICH receiving unit 105 cannot detect “ACK” and “NACK”, the transmission power value calculation unit 106 transmits the initial transmission power value Ppreini of the preamble part calculated earlier and the retransmission of the preamble part extracted first. The power offset value ΔP0 at the time is applied to the following equation (3) to calculate the power value Ppre of the retransmission preamble part.
Ppre = Ppreini + ΔP0 (3)

In the same procedure, the preamble part is retransmitted from the RF unit 102 using the calculated power value Ppre. When the AICH receiving unit 105 can detect “ACK” and “NACK” for the retransmission of the preamble part, the transmission power value calculating unit 106 transmits the power value Ppre calculated for retransmission and the previously extracted message. The power offset value ΔPp-m at the time of part transmission is applied to the following equation (4) to calculate the power value Pmes for message part transmission.
Pmes = Ppre + ΔPp−m (4)

  The calculated message part transmission power value Pmes is input to the initial transmission power correction value calculation unit 108 and stored in the RACH successful transmission power value storage unit 202.

On the other hand, when the AICH receiving unit 105 cannot detect “ACK” and “NACK” for retransmission of the preamble part, the transmission power value calculating unit 106 first calculates the power value Ppre calculated for the first retransmission. The extracted power offset value ΔP0 at the time of retransmission of the preamble part is applied to the following equation (5) to calculate the power value Ppre of the second retransmission preamble part.
Ppre = Ppre + ΔP0 (5)

  In the same procedure, the RF part 102 retransmits the preamble part using the calculated second power value Ppre. When the AICH receiving unit 105 can detect “ACK” and “NACK” for the retransmission of the preamble part, the transmission power value calculating unit 106 applies the second power value Ppre to Equation (4). Then, the power value Pmes for message part transmission is calculated.

  The RACH successful transmission power value storage unit 202 of the initial transmission power correction value calculation unit 108 stores the second retransmission power value Ppre.

  On the other hand, when the AICH receiving unit 105 cannot detect “ACK” and “NACK” for the second retransmission, the transmission power value calculating unit 106 updates the retransmission power value Ppre using Equation (5). . If the number of retransmissions of the preamble part does not reach the maximum number of transmissions designated by the base station, transmission power value calculation section 106 updates retransmission power value Ppre according to equation (5) until “ACK” and “NACK” can be received. repeat.

  The contents of the above open loop transmission power control are collectively shown in FIG. 3, for example. FIG. 3 is a conceptual diagram illustrating open loop transmission power control. In FIG. 3, the preamble parts 301b and 301c are transmitted while gradually increasing the transmission power value of the first transmission preamble part 301a by the offset value ΔP0, and “ACK” can be received by the third transmission of the preamble part 301c, thereby enabling random access. It is shown that the message part 302 is transmitted after the offset value ΔPp-m is added since it succeeded.

  Thus, when the random access is successful, the initial transmission power correction value is calculated by the initial transmission power correction value calculation unit 108 as follows. In FIG. 2, in the initial transmission power correction value calculation unit 108, first, the subtraction unit 203 stores the initial transmission power calculation value stored in the initial transmission power calculation value storage unit 201 and the RACH successful transmission power value storage unit 202. A difference from the transmission power value at the time of successful random access is taken.

  Next, the gain 204 is multiplied so that the difference can be weighted, and the averaging unit 205 averages the difference. The averaging unit 205 uses an averaging method that can adjust past weights by the IIR filter or an averaging method such as a moving average. The average value in the averaging unit 205 may be cleared for a certain period after the power is turned on, or may be cleared every time open loop transmission power control is performed on the random access channel.

  The correction value generation unit 206 determines a correction value Pcomp for the initial transmission power from the averaged result, and feeds it back to the transmission power value calculation unit 106. The correction value generation unit 206 may have a function of limiting the maximum correction value or a function of suppressing a sudden change in the transmission power value by gradually approaching the correction amount to the calculated correction value. it can.

The transmission power value calculation unit 106 calculates the initial transmission power value Ppreini of the preamble part when the next and subsequent random accesses are performed by the following equation (6) in which the correction value Pcomp is added to the right side of the equation (1).
Ppreini = Pbs−RSCP + Puri + Pue + Pcomp (6)

  Thus, according to the transmission / reception apparatus according to the present embodiment, the correction value is obtained from the difference between the transmission power value of the preamble part when the random access was successful in the past and the initial transmission power value calculated at that time, Since the value obtained by adding the correction value to the initial transmission power calculation value of the preamble part is used as the initial transmission power calculation value used in the next open loop transmission power control, the initial transmission power calculation value can be made closer to the optimum value. it can.

  Therefore, it is possible to reduce the number of unnecessary retransmissions of the preamble part in the random access procedure, and it is possible to reduce the reception level measurement error of open loop transmission power control and the transmission power value variation of the transmitter. Can be increased.

  The transmitting / receiving apparatus according to the present invention is mounted on a mobile station in a W-CDMA mobile communication system, and is suitable for performing open loop transmission power control with reduced generation of useless ramping operations.

The block diagram which shows the structure of the transmitter / receiver which concerns on one embodiment of this invention FIG. 1 is a block diagram showing an example of the configuration of an initial transmission power correction value calculation unit shown in FIG. Conceptual diagram explaining open-loop transmission power control

Explanation of symbols

100 transceiver 101 antenna 102 wireless unit (RF unit)
DESCRIPTION OF SYMBOLS 103 Transmission power calculation information receiving part 104 Reception level measurement part 105 AICH receiving part 106 Transmission power value calculation part 107 Random access channel transmission part (RACH transmission part)
108 Initial Transmission Power Correction Value Calculation Unit 201 Initial Transmission Power Calculation Value Storage Unit 202 Random Access Channel Successful Transmission Power Value Storage Unit (RACH Successful Transmission Power Value Storage Unit)
203 Subtraction unit 204 Gain unit 205 Average unit 206 Correction value generation unit 301a, 301b, 301c Preamble part 302 Message part

Claims (3)

  Means for calculating a correction value of the initial transmission power value from a difference between a transmission power value when the random access by the open loop transmission power control performed in the past is successful and the initial transmission power value calculated at that time; and A transmission / reception apparatus comprising: means for calculating an initial transmission power value used in a next open loop transmission power control based on an initial transmission power value and the correction value.   A mobile station apparatus comprising the transmission / reception apparatus according to claim 1.   A mobile communication system according to claim 2, wherein the mobile station apparatus according to claim 2 is arranged under each base station apparatus.

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