KR100854513B1 - Method and system for automatic setting of initial transmission power through random access channel - Google Patents

Abstract

A method and system for automatically setting initial transmit power over a random access channel are provided.

According to an embodiment of the present invention, a method for automatically setting initial transmission power through a random access channel may include: automatically setting, by a mobile communication network, a predetermined constant value for calculating an initial transmission power of a mobile terminal; Transmitting, by the mobile communication network, the set constant value to the mobile terminal; And calculating, by the mobile terminal, the initial transmission power using the received constant value.

Description

Method and system for automatically setting initial power through Random Access Channel

1 is a diagram illustrating a general initial access procedure in a mobile communication system.

2 is a diagram illustrating ramping of initial transmit power through a general random access channel.

3 is a diagram comparing a normal case and an abnormal case of transmission of a preamble.

4 is a flowchart illustrating a method for automatically setting initial transmit power through a random access channel according to an embodiment of the present invention.

5 is a diagram illustrating a system for automatically setting initial transmit power through a random access channel according to an embodiment of the present invention.

(Description of the main parts of the drawing)

100: mobile terminal 200: mobile communication network

210: base station 220: base station controller

230: core network 240: home location register (HLR)

The present invention relates to the control of the initial transmission power in the mobile communication system, and more particularly, the optimal initial power for each cell to transmit the preamble by using a constant value automatically designated by the mobile communication network for each cell A method and system for automatically setting initial transmit power over a random access channel capable of calculating an initial transmit power value.

Today, there are three major mobile communication systems worldwide. First, the Global System for Mobile Communication (GSM) system centered on Europe, the second generation mobile communication system, and Second, the synchronous CDMA (Code Division Multiple Access) 2000 system centered on Korea and the US, the third generation system, and Third, Europe, the third generation system. The central UMTS (Universal Mobile Telecommunication Services) system is used.

UMTS, the third generation mobile communication system called IMT-2000 in Europe, is leading the standardization in the 3GPP (3 Generation Partnership Project). It is a personal communication service using asynchronous technology based on GSM method. The UMTS mobile communication system has a big difference in that it does not use a Global Position System (GPS) for synchronization compared to other 3G system CDMA 2000 systems, and thus is called an asynchronous mobile communication system.

The asynchronous mobile communication system is a standard developed by combining CDMA technology with European GSM. The UMTS system integrates various systems such as cellular, wireless telephone, wireless LAN and satellite communication, and provides international roaming to make a call anywhere in the world. In addition, it supports multimedia services such as voice and image data at variable rates of up to 2Mbps, and is used in the same requirements and the same frequency band as IMT-2000, such as interworking with various broadband networks.

In such a UMTS system, when a mobile terminal initially accesses a wireless network, the mobile terminal transmits a signal through a random access channel (RACH). Since the random access channel is shared and used by a plurality of mobile terminals, collision may occur. When multiple mobile stations transmit signals on a random access channel at the same time, collisions occur and the base station cannot recover the signals. Therefore, a plurality of preambles are transmitted before sending a message for minimizing the collision of the random access channel. The transmission power of these preambles is changed to increase the initial access success probability of the mobile terminal.

However, since the maximum transmit power of the mobile terminal using the CDMA system is not limited, high power of 23 dBm or more may be used in the edge section of the cell, and the initial transmit power may be set high because the preamble and the message are simultaneously transmitted. However, in the WCDMA system, which can be called a wireless access method in the UMTS system, the initial transmission power is limited to 24 dBm and does not require a high initial transmission power value because only the preamble is transmitted without transmitting a message during the initial access. . As a result, when the initial transmission power setting error occurs in the WCDMA system, excessive maximum transmission power is transmitted in the edge section of the cell, and the overall transmission power of the mobile terminal is increased, causing unnecessary interference to adjacent cells. have.

SUMMARY OF THE INVENTION The present invention has been devised to solve the above problems, and the technical problem to be solved by the present invention is an excessive initial transmission power that is more than necessary by automatically calculating different initial transmission power values for each cell based on a parameter set by a system operator. The present invention provides a method and system for automatically setting initial transmission power through a random access channel, which can minimize interference of other adjacent cells and contribute to improving call traffic.

The object of the present invention is not limited to the above-mentioned object, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, a method for automatically setting initial transmission power through a random access channel according to an embodiment of the present invention may determine whether a mobile communication network automatically sets a predetermined constant value for calculating an initial transmission power of a mobile terminal. Automatically setting the constant value in accordance with a first parameter indicating whether or not; Transmitting, by the mobile communication network, the set constant value to the mobile terminal; And calculating, by the mobile terminal, the initial transmit power using the received constant value, wherein the constant value includes: a primary CPICH DL Tx power of the common pilot channel and a value of the common pilot channel; It is automatically set using the received signal code power value CPICH_RSCP and the uplink interference value (UL Interference).

Preferably, prior to the automatic setting, the first parameter, a second parameter indicating a specific value within a range of a received signal code power value of the mobile terminal, and the mobile communication network set the constant value. Setting a third parameter indicating whether to periodically transmit to the mobile terminal.

In addition, the automatic setting system of the initial transmission power through the random access channel according to an embodiment of the present invention for achieving the above object, indicating whether to automatically set a predetermined constant value for calculating the initial transmission power A mobile communication network for automatically setting the constant value according to a first parameter; And a mobile terminal configured to receive the set constant value from the mobile communication network to calculate the initial transmission power, wherein the constant value includes: a primary CPICH DL Tx power of a common pilot channel and a value of the common pilot channel; It is automatically set using the received signal code power value CPICH_RSCP and the uplink interference value (UL Interference).

Preferably, the constant value may be set for each cell of the mobile communication network.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms, and the present embodiments merely make the disclosure of the present invention complete, and are common in the art to which the present invention pertains. It is provided to fully inform those skilled in the art of the scope of the invention, which is to be defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

The random access channel (RACH) used in the UMTS system is an uplink random access channel, which is a channel for accessing a mobile terminal to UTRAN, which is a mobile communication network. The RACH is mainly used for transmitting a Radio Resource Control (RRC) connection message for accessing the UTRAN when the mobile terminal is paged or attempts to make a call. In addition, the RACH is used to update or update the cell when the mobile terminal is connected to the UTRAN. In case of transmitting UTRAN Registration Area (UPRAN) update message, it is used in case of transmitting very small data in Cell_FACH (Forward Access Channel) state.

The transmission of the preamble through the random access channel and the transmission of the preamble detection information through the Acquisition Indication Channel (AICH), which is a response thereof, will be briefly described with reference to FIGS. 1 and 2.

FIG. 1 is a diagram illustrating a general initial access procedure in a mobile communication system, and FIG. 2 is a diagram illustrating ramping of initial transmit power through a general random access channel.

Referring to FIG. 1, a preamble configured by a specific bit string as a base station in a mobile communication network 200 to access a mobile communication network 200 including a base station and a radio network controller (RNC). Is transmitted through the random access channel (S102). At this time, the mobile terminal 100 determines the initial transmission power for the first preamble transmission according to Equation 1 below.

<Equation 1>

P _{initial _power =} Primary CPICH DL TX Power-CPICH_RSCP + UL_Interference + Constant Value.

In Equation 1, P _{initial _} power means an initial transmit power value for transmitting the RACH preamble, Primary CPICH DL TX Power means a transmit power value of the primary Common Channel (CPICH), CPICH_RSCP of the CPICH Received Signal Code Power (RSCP) value, UL_Interference means UL (UpLink) interference value, Constant Value means a constant value.

Here, Primary CPICH DL TX Power, UL_Interference, which is an uplink interference value, and Contant Value, which is a constant value, are values included in a system information message transmitted from the mobile communication network 200, and CPICH_RSCP is measured by the mobile terminal 100. Is a value. That is, the mobile terminal 100 measures the CPICH_RSCP value and uses the system information message received from the mobile communication network 200 with the strength of the initial transmission power as shown in Equation 1, through the random access channel. The preamble data is transmitted to the base station of the mobile communication network 200. After transmitting the first preamble data 302 shown in FIG. 2, the mobile terminal 100 waits until the preamble detection information 310 is detected through the AICH from the base station of the mobile communication network 200.

Thereafter, if the preamble detection information 310 is not received from the base station for a certain time, the mobile terminal 100 _ramps P more than the initial transmission power immediately before. The second preamble 304 increased by the number is transmitted to the base station of the mobile communication network 200 through the random access channel (S104). If the second preamble 304 also fails to receive the preamble detection information 310 from the base station to the AICH, the mobile terminal 100 increases the transmit power by the power ramping step P _ramping until the mobile station 100 receives the preamble detection information 310. Retransmit the preamble until the number of retransmissions. That is, the third preamble 306 to the n th preamble 308 are retransmitted.

If the preamble data 308 is transmitted up to the maximum number of retransmissions and the base station does not receive the preamble detection information 310 through the AICH, the mobile terminal 100 stops the initial access procedure through the random access channel. However, when the mobile terminal 100 receives and detects the detection information 310 of the preamble from the base station (S106), the initial access process through the random access channel is terminated.

However, when the mobile terminal 100 does not receive the preamble detection information 310 in the previous step, it can be seen that the power for transmitting the preamble in the next step is the power that increased P _ramping back to the transmission power of the previous step. have. That is, the initial transmission power value when the mobile terminal 100 transmits the nth preamble 308 is expressed by Equation 2 below.

<Equation 2>

P _n = P _{initial _power} + (n-1) * P _ramping

Here, n is the number of times the mobile terminal 100 transmits the preamble, and has a value greater than 1 and smaller than the maximum number of retransmissions (maxRetransCount). P _n is a power value when transmitting the n-th preamble 308, P _{initial _power} is the initial transmission power value obtained through <Equation 1>, P _ramping means a power ramping step value. . The P _ramping and the maximum number of retransmissions (maxRetransCount) are received from the mobile communication network 200. The P _ramping values are defined in dB units from a minimum of 1 dB to a maximum of 8 dB in the current recommendation.

Meanwhile, referring back to FIG. 2, the mobile terminal 100 transmits the first preamble 302 using the transmission power 302 having a size of P _{initial _} power value. Thereafter, the mobile terminal 100 continuously transmits up to n times while increasing power by P _ramping to the transmission power 302 until receiving the preamble detection information 310 from the base station to the AICH. When the base station recognizes the n-th preamble 308 and gives the preamble detection information 310 to the mobile terminal 100 through the AICH, the mobile terminal 100 transmits an RACH message 312 to the next slot allocated thereto. It sends the signal and executes the signaling connection setup procedure.

Therefore, when the base station recognizes the n-th preamble 308 transmitted by the mobile terminal 100 and transmits the preamble detection information 310 to the mobile terminal 100 in the AICH, the mobile terminal 100 RACH in the next slot. The message 312 is loaded and transmitted to the mobile communication network 200. Here, since the base station did not recognize the n-th preambles 302, 304, and 306 transmitted by the mobile terminal 100, P _{initial _power} (n-1) + P _ramping * (n-2) additional power consumption will occur, and corresponding battery life will be reduced.

Now, a case in which the transmission of the preamble transmitted by the mobile terminal 100 through the RACH is abnormally described and an embodiment for solving the problem will be described with reference to FIGS. 3 to 5.

First, the transmission point of the maximum transmission power of the mobile terminal 100 will be obtained by using Equation 1 described above. _{Assume that} the maximum value of P _{initial _power} is 24dBm, UL_Interference is -105, Primary CPICH DL TX Power is 33dBm, and Constant Value is -20.

24 = 33-CPICH_RSCP + (-105) + (-20),

CPICH_RSCP = -116 dBm.

That is, the mobile terminal 100 transmits a maximum transmit power of 24 dBm at the point where the CPICH_RSCP value becomes -116 dBm. Therefore, the initial transmission power value of the mobile terminal 100 is not constant according to the values of Primary CPICH DL TX Power and UL_Interference having different values for each cell, and are different for each cell. For example, assuming that the mobile terminal 100 switches to out of coverage at the point where the CPICH_RSCP value is -119 dBm, the operator operates with the ConstantValue at -15, and the UL_Interference of the base station is measured as -102, 24 = 33-CPICH_RSCP + (-102) + (-15), where CPICH_RSCP is -108 dBm. This result is that the mobile terminal 100 transmits the initial transmission power of the mobile terminal 100 to the maximum from -108dBm point, which cannot be referred to as the edge of the cell, and may cause a large interference, thereby causing a decrease in call communication. It can also be.

Referring to FIG. 3, which compares a normal case with an abnormal case of transmission of the preamble, as shown in the normal case 520 on the right side of the cell edge, the transmit power of the preamble is gradually increased to increase the set of calls. Up should be progressed. As shown in the abnormal case (510) on the left side, since the transmission is continuously performed with the maximum transmission power of 24 dBm, the initial transmission power of the mobile station in the cover area of the base station is increased. .

Therefore, the constant value (Constant Value) in Equation (1) is automatically assigned to the mobile terminal 100 through SIB (System Information Block) 5 or 7, the mobile terminal for each cell By setting the proper initial transmit power to transmit the preamble, it is possible to minimize interference to neighboring cells. An embodiment for solving such a problem will be described with reference to FIG. 4.

4 is a flowchart illustrating a method for automatically setting initial transmit power through a random access channel according to an embodiment of the present invention.

First, the system operator may include a first parameter indicating whether to automatically set a Constant Value of Equation 1, and a second value indicating a specific value within a range of an RSCP value of the mobile terminal 100. A second parameter and a third parameter indicating whether to periodically transmit the constant value set in the mobile communication network 200 to the mobile terminal 100 are set (S202). The first parameter and the third parameter may have a binary value of On or Off, and the second parameter may have a specific value within a range of -100 dBm to -150 dBm. Of course, the setting of such a parameter is just one example for automatic setting of a constant value according to an embodiment of the present invention, the operator may set a different parameter and the system allows the range of the second parameter. Can be set differently in the range.

In the mobile communication network 200, the constant value of Equation 1 is adaptively set according to the environment of each cell by using the parameters set by the operator (S204). The process of automatically setting these constant values will be described.

First, assuming that the second parameter value is -119dBm, the Primary CPICH DL Tx Power is 35dBm, and the UL_Interference is -104 when the first parameter has an On value, the base station controller is as follows. The equation will automatically calculate the constant value.

ConstantValue = 24-Primary CPICH DL Tx Power + CPICH_RSCP-UL Interference.

Here, the Primary CPICH DL Tx Power means a transmission power value of a common pilot channel (CPICH), the CPICH_RSCP is an RSCP value of the common pilot channel means a value specified by the second parameter, the UL Interference is Means uplink (UL) interference value. Substituting a numerical value into the above equation results in ConstantValue = 24-35 + (-119)-(-104), and a constant value of -26 is automatically obtained.

Now, the mobile communication network 200 transmits the constant value calculated by the above-described process to the mobile terminal 100 (S206). When the third parameter has a value of On, the base station controller of the mobile communication network 200 periodically transmits the automatically obtained constant value to the mobile terminal 100 through system information block (SIB) # 5. Will be sent. However, when the third parameter has an Off value, the mobile communication network 200 transmits the constant value to the mobile terminal 100 through the system information block (SIB) 5 only when the call is set up. Done.

The mobile terminal 100 receiving the constant value automatically set for each cell from the mobile communication network 200 calculates initial transmission power for transmitting the preamble using the constant value for each cell (S208). The process of calculating the initial transmit power is calculated using Equation 1 defined in the 3GPP standard. That _{is, P initial _power = Primary CPICH DL} Tx Power - using the formula of CPICH_RSCP + UL Interference + ConstantValue calculates the P _{initial _power.}

5 is a diagram illustrating a system for automatically setting initial transmit power through a random access channel. Referring to FIG. 5, the automatic configuration system includes a mobile terminal 100 and a mobile communication network 200, and the mobile communication network 200 includes a base station 210, a base station controller 220, and a core network 230. ) And home location register 240. Since a call setup process or a signal exchange process in a general mobile communication system is known to those skilled in the art, only a function for automatic setting of initial transmission power according to an embodiment of the present invention will be briefly described herein.

The base station controller 220 of the mobile communication network 200 automatically sets a constant value for calculating initial transmission power using the first parameter, the second parameter, and the third parameter set by the operator. When the third parameter has a value of ON, the base station controller 220 of the mobile communication network 200 periodically sends the constant value to the mobile terminal 100 through a system information block (SIB) No. 5. send. When the third parameter has an off value, the base station controller 220 sends the constant value to the mobile terminal 100 through the system information block (SIB) 5 only when the mobile terminal 100 sets up a call. send.

The mobile terminal 100 receives the set constant value from the base station controller 220 of the mobile communication network 200 and calculates initial transmission power. In this case, the mobile terminal 100 calculates an initial transmit power using Equation 1 defined in the 3GPP standard.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the embodiment of the present invention as described above one or more of the following effects exist.

By automatically calculating different initial transmit power values for each cell based on the parameters set by the system operator, it is possible to minimize interference of other adjacent cells due to excessive initial transmit power more than necessary and contribute to improving call traffic rate.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Claims (16)

A method for automatically setting initial transmit power for transmitting a preamble through a random access channel, Automatically setting the constant value according to a first parameter indicating whether the mobile communication network automatically sets a predetermined constant value for calculating an initial transmission power of the mobile terminal; Transmitting, by the mobile communication network, the set constant value to the mobile terminal; And Calculating, by the mobile terminal, the initial transmission power using the received constant value; The constant value is automatically set by using a primary CPICH DL Tx Power, a common pilot channel received signal code power value CPICH_RSCP, and an uplink interference value UL Interference. , A method of automatically setting initial transmit power through a random access channel. The method of claim 1, Before the step of automatically setting, A third parameter indicating whether the first parameter is a second parameter indicating a specific value within a range of a received signal code power value of the mobile terminal and whether the mobile communication network periodically transmits the set constant value to the mobile terminal; Setting a parameter further comprising: setting an initial transmit power over a random access channel. The method of claim 2, The first parameter and the third parameter has a value of on or off, the second parameter has a specific value in the range of -100dBm to -150dBm, the method of automatically setting the initial transmit power over a random access channel. The method of claim 3, wherein The constant value is automatically set by the following equation when the first parameter has a value of on, ConstantValue = 24-Primary CPICH DL Tx Power + CPICH_RSCP-UL Interference Here, the Primary CPICH DL Tx Power refers to a transmission power value of a common pilot channel (CPICH), and the CPICH_RSCP refers to a value designated by the second parameter as a received signal code power (RSCP) value of the common pilot channel. And wherein the UL Interference means an uplink (UL) interference value, and the Constant Value means the constant value. The method of claim 3, wherein The transmitting step, If the third parameter has a value of ON, periodically transmitting, by the mobile communication network, the constant value to the mobile terminal through system information block (SIB) No. 5; How to set the transmission power automatically. The method of claim 3, wherein The transmitting step, If the third parameter has a value of off, transmitting the constant value to the mobile terminal through system information block (SIB) 5 only when the mobile network establishes a call. How to automatically set the initial transmit power through. The method of claim 1, The calculating of the initial transmission power, Computing using the following equation, P _{initial _power =} Primary CPICH DL Tx Power-CPICH_RSCP + UL Interference + ConstantValue Here, P _{initial _power} means an initial transmission power value for transmitting a preamble, the Primary CPICH DL Tx Power means a transmission power value of a common pilot channel (CPICH), the CPICH_RSCP is the reception of the common pilot channel A signal code power (RSCP) value, the UL Interference means an uplink (UL) interference value, and the Constant Value refers to the received constant value, automatic setting of the initial transmit power through a random access channel Way. The method of claim 1, And the constant value is set for each cell of the mobile communication network. A system for automatically setting initial transmit power for transmitting a preamble through a random access channel, A mobile communication network for automatically setting the constant value according to a first parameter indicating whether to automatically set a predetermined constant value for calculating the initial transmission power; And A mobile terminal for receiving the set constant value from the mobile communication network to calculate the initial transmission power; The constant value is automatically set by using a primary CPICH DL Tx Power, a common pilot channel received signal code power value CPICH_RSCP, and an uplink interference value UL Interference. , Automatic setting system of initial transmit power through random access channel. The method of claim 9, The mobile communication network, A first parameter, a second parameter indicating a specific value within a range of a received signal code power value of the mobile terminal, and a third indicating whether the mobile communication network periodically transmits the set constant value to the mobile terminal A system for automatically setting initial transmit power over a random access channel for setting parameters. The method of claim 10, Wherein the first parameter and the third parameter have a value of on or off, and the second parameter has a specific value in the range of -100 dBm to -150 dBm. The method of claim 11, The mobile communication network, When the first parameter has a value of ON, the constant value is automatically set by the following equation, ConstantValue = 24-Primary CPICH DL Tx Power + CPICH_RSCP-UL Interference Here, the Primary CPICH DL Tx Power refers to a transmission power value of a common pilot channel (CPICH), and the CPICH_RSCP refers to a value designated by the second parameter as a received signal code power (RSCP) value of the common pilot channel. Wherein the UL Interference means an uplink (UL) interference value, and the Constant Value means the constant value. The method of claim 11, The mobile communication network, And if the third parameter has a value of ON, periodically transmitting the constant value to the mobile terminal through system information block (SIB) # 5. The method of claim 11, The mobile communication network, If the third parameter has a value of off, automatically setting initial transmit power over a random access channel, transmitting the constant value to the mobile terminal via system information block (SIB) 5 only when a call is set up; system. The method of claim 9, The mobile terminal, The initial transmit power is calculated using the following equation, P _{initial _power =} Primary CPICH DL Tx Power-CPICH_RSCP + UL Interference + ConstantValue Here, P _{initial _} power means an initial transmission power value for transmitting a preamble, the Primary CPICH DL Tx Power means a transmission power value of a common pilot channel (CPICH), the CPICH_RSCP is the reception of the common pilot channel A signal code power (RSCP) value, the UL Interference means an uplink (UL) interference value, and the Constant Value refers to the received constant value, automatic setting of the initial transmit power through a random access channel system. The method of claim 9, And the constant value is set for each cell of the mobile communication network.

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