KR100846866B1 - Method for controlling transmission power of a control channel in a radio communication terminal - Google Patents

Abstract

The present invention provides a transmission power of a second uplink control channel that can be received by two or more cell base stations to help demodulate a first uplink control channel for controlling a downlink shared channel provided by a cell in a cellular wireless communication system. It relates to a technique for efficiently controlling. When the provision of the first uplink control channel is terminated, the present invention allows the transmit power of the second uplink control channel to decrease the increased transmit power for the first uplink control channel. Particularly, in the IMT-2000 HSDPA system, the present invention provides a method for increasing the DPCCH transmission power to a predetermined level so that the base station serving the HSDPA can be easily received by the terminal in the soft handover state when the HS-DPCCH transmission starts. 1 course; This is achieved by a second process of reducing the DPCCH transmit power by the increased level at the end of HS-DPCCH transmission.

Description

Control channel transmission power control method of wireless communication terminal {METHOD FOR CONTROLLING TRANSMISSION POWER OF A CONTROL CHANNEL IN A RADIO COMMUNICATION TERMINAL}

1 is a diagram illustrating a case where N terminals are in soft handover state with several base stations.

2 is an explanatory diagram illustrating the intermittent transmission of HS-DPCCH, which is a control channel for HSDPA, while continuously transmitting DPCCH, which is a general control channel;

3 is an explanatory diagram showing a conventional DPCCH transmission power control method when a terminal for transmitting an HS-DPCCH is in a soft handover state;

4 is an explanatory diagram showing a power adjustment method of a DPCCH in a soft handover state according to the present invention;

*** Description of the symbols for the main parts of the drawings ***

11A-11N: Base Station 12: Terminal

The present invention provides a transmission power of a second uplink control channel that can be received by two or more cell base stations to support demodulation of a first uplink control channel for controlling a downlink shared channel provided by a cell in a cellular wireless communication system. The present invention relates to a technology for more efficient control, and more particularly to a technique for controlling uplink DPCCH transmission power of a terminal in soft handover state in an IMT-2000 HSDPA system. The present invention relates to a control channel transmission power control method of a wireless communication terminal to be quickly restored to the required level.

Proper transmission power control of the uplink in a CDMA communication system is essential for increasing system capacity. In particular, a CDMA terminal in a soft handover state receives power control commands by a plurality of base stations, and considers all of these commands, and transmits them to the uplink according to a level that can be received by one of the base stations. Determine the transmit power of. When one terminal in a soft handover state transmits a plurality of channels at the same time, some of the channels are received only by one base station, not a plurality of base stations. In this case, the terminal needs to adjust the power control scheme of the uplink channels for efficient reception at the base station.

In a cellular wireless communication system, a base station of a cell provides a downlink shared channel to a plurality of terminals in a cell. The downlink shared channel is exclusively owned by a specific terminal for a specific time, so that one terminal is dedicated. In order to control such a downlink shared channel, the specific terminal transmits control information to the cell base station through an uplink channel. In order to receive the uplink control channel signal from the base station, a general control channel signal of the terminal should be used.                         

However, the general control channel is not only received by one base station, but can be simultaneously received by several base stations, and thus the transmission power may be sufficient to be received by only one base station among several base stations. If the base station transmitting the downlink shared channel is different from the base station transmitting the downlink shared channel, the base station transmitting the downlink shared channel may not receive a signal of a general control channel that controls the transmission power according to the good base station. It was unreasonable.

Therefore, when transmitting a signal to the control channel for controlling the downlink shared channel, the terminal is to adjust the transmission power of the general control channel up. Hereinafter, the IMT-2000 HADPA system will be described as an example.

The HS-DPCCH of the IMT-2000 HADPA system corresponds to such a channel, and an additional power control scheme for efficient reception of the HS-DPCCH has already been proposed. By using this method, however, the reception performance of the HS-DPCCH can be improved, but the degree of interference of the uplink is increased than when using the conventional power control scheme.

The HS-DPCCH of the uplink channel of the IMT-2000 HSDPA is received only by the base station serving the HSDPA to the terminal even if the terminal is in soft handover state with a plurality of base stations. The terminal in the soft handover state transmits the HS-DPCCH at a transmission power proportional to the transmission power of the DPCCH, which is a channel already transmitted on the uplink, and the base station transmits the pilot through the DPCCH to demodulate the information of the HS-DPCCH. Signal. At this time, the power control of the DPCCH is transmitted to the minimum power that can be received by any of the base stations participating in the soft handover, so that the power of the pilot transmitted through the DPCCH is received only by one base station. It may be insufficient to demodulate the DPCCH. Therefore, in an additional scheme, the UE estimates the transmission power of the DPCCH required for demodulating the HS-DPCCH at the moment of starting the HS-DPCCH transmission, and increases the transmission power of the DPCCH by the estimated amount.

A general transmission power control method of a terminal in soft handover state in an IMT-2000 system will now be described.

In the IMT-2000 system, the UE continuously transmits the general control channel DPCCH along with the general traffic channel on the uplink. In addition, the terminal transmits a pilot for traffic channel demodulation and other necessary control information through the DPCCH.

로 표시하였다.

인 경우를 전력 상승(up) 명령으로,

인 경우를 전력 하강(down) 명령으로 가정한다면 도 1의 예에서 1번 기지국(11A)은 현재의 DPCCH 수신 전력값이 필요 이상으로 높은 값이라고 판단하여 전력 하강 명령을 내렸으나 N-1 번, N 번 기지국(11N-1),(11N)은 현재의 DPCCH 수신 전력값이 너무 작은 값이라고 판단하여 전력 상승 명령을 내렸다. 모든 기지국(11A-11N)으로부터 DPCCH 전력 제어 명령을 수신한 단말기(12)는 단 하나의 기지국에서라도 전력 하강 명령이 수신되었을 경우 적어도 그 기지국에서는 DPCCH의 수신이 가능할 것으로 판단하여 DPCCH 송신 전력을 미리 정해진 전력 조정 상수인 △TPC 만큼 낮추게 되며, 모든 기지국(11A-11N)으로부터 전력 상승 명령을 수신했을 경우에만 DPCCH 송신전력을 △TPC만큼 상승시키게 된다.The terminal in the soft handover state receives a transmit power control command for the DPCCH from all base stations participating in the soft handover. At this time, the received power of the DPCCH received at each base station varies depending on the environment up to each base station, and each base station may send different power control commands according to the received power of the received DPCCH. 1 shows an example in which the terminal (mobile phone) 12 is in a soft handover state with N base stations 11A-11N, and the power control command transmitted from the i-th base station to the terminal 12 is shown in FIG.

Marked as.

Is the power up command,

In the example of FIG. 1, the base station 11A in the example of FIG. 1 determines that the current DPCCH received power value is higher than necessary, and gives the power down command. N base stations 11N-1 and 11N determine that the current DPCCH received power value is too small, and give a power-up command. Upon receiving the DPCCH power control command from all base stations 11A-11N, the terminal 12 determines that the DPCCH transmission power can be received at least by the base station when the power down command is received even at only one base station. The DPCCH transmission power is increased by DELTA TPC only when the power up command is received from all base stations 11A-11N.

를 단말기(12)가 대응하는 슬롯에서 전송할 DPCCH 전송 전력의 증가분이라고 한다면, TPC_comb는,That is, TPC_comb is referred to as a power control value determined by the terminal 12 in consideration of power control commands from all base stations 11A-11N.

If the terminal 12 is an increase of the DPCCH transmit power to be transmitted in the corresponding slot, TPC_comb,

,

, ...,

이 모두 1일 경우 : TPC_comb = 1

,

, ...,

If these are all 1: TPC_comb = 1

,

, ...,

중 한 값이라도 -1일 경우 : TPC_comb = -1과 같이 구하며,

는 다음의 [수학식1]로 표현된다.

,

, ...,

If any value is -1, get TPC_comb = -1

Is expressed by Equation 1 below.

= TPC_comb ×

= TPC_comb ×

In addition, the additional transmission power control method of the terminal in the soft handover state in the IMT-2000 HSDPA system will be described.

The terminal using the HSDPA service in the IMT-2000 system continuously transmits the DPCCH, which is a general control channel, as shown in FIG. 2 on the uplink, and intermittently transmits the HS-DPCCH, which is a control channel for the HSDPA. At this time, the base station serving the HSDPA to the terminal uses the pilot signal transmitted through the DPCCH for demodulation of the HS-DPCCH. The transmit power of the HS-DPCCH is determined to be a value proportional to the transmit power of the DPCCH. That is, the transmission power of the HS-DPCCH is changed according to the transmission power of the DPCCH.

Since the DPCCH is received by all base stations participating in the soft handover when the terminal is in the soft handover state, transmission power control is performed according to the latter transmission power control method. However, since the HS-DPCCH is received only by the base station serving the HSDPA to the terminal, when the transmission power of the HS-DPCCH is set in proportion to the transmission power of the DPCCH, the HS-DPCCH received power at the base station serving the HSDPA is required. May be shorter. In addition, the received power of the DPCCH pilot signal at the base station serving the HSDPA may also be insufficient for demodulating the HS-DPCCH. In order to solve this problem, in the case of a UE having a soft handover state and receiving an HSDPA service, an additional method of modifying the transmission power control method of the DPCCH has been proposed only in a section in which the HS-DPCCH is transmitted.

는 HSDPA 서비스를 제공하는 기지국으로부터 수신한 전력 제어 명령, TPC_comb(i)는 모든 기지국으로부터 수신한 전력 제어 명령으로부터 상기 후자의 전송 전력 제어 방법과 같이 구한 전력 제어 명령을 나타낸다. 단말기는 HS-DPCCH를 전송하기 전 K_used 슬롯 동안의 값 TPC_comb(1), TPC_comb(2), ..., TPC_comb(K_used-1), TPC_comb(K_used) 와

,

, ...,

,

를 저장해 놓은 뒤에 이 값들을 이용해서 HS-DPCCH가 전송되는 슬롯에서의 DPCCH 전송에 필요한 추가 전력을 위한 값 d를 추정한다. 상기 d의 추정 방법은 시스템 구현에 따라 다를 수 있다. 이 때에 HS-DPCCH가 전송되는 슬롯에서의 DPCCH 전송 전력의 증가는 다음의 [수학식2]로 표현된다.3 illustrates a method of controlling DPCCH transmission power when a terminal transmitting an HS-DPCCH is in a soft handover state. For the slot before the i slot for transmitting the HS-DPCCH,

Denotes a power control command received from a base station providing an HSDPA service, and TPC_comb (i) indicates a power control command obtained in the same way as the latter transmission power control method from the power control commands received from all base stations. The terminal transmits values TPC_comb (1), TPC_comb (2), ..., TPC_comb (K_used-1), and TPC_comb (K_used) during the K_used slot before transmitting the HS-DPCCH.

,

, ...,

,

After storing, use these values to estimate the value d for the additional power required for DPCCH transmission in the slot where the HS-DPCCH is transmitted. The method of estimating d may vary depending on the system implementation. At this time, the increase of the DPCCH transmission power in the slot in which the HS-DPCCH is transmitted is represented by the following [Equation 2].

는 HS-DPCCH가 전송되는 슬롯에 대한 HSDPA를 서비스하는 기지국으로부터의 전력 제어 명령을 의미한다.here,

Denotes a power control command from the base station servicing the HSDPA for the slot in which the HS-DPCCH is transmitted.

로 나타낼 수 있으며,

슬롯 이내에 이미 HS-DPCCH가 전송됐을 경우에는 K_used 값은 마지막으로 HS-DPCCH를 전송한 슬롯과 현재 HS-DPCCH를 전송할 슬롯 사이의 개수로 조정된다. HS-DPCCH를 전송하지 않은 슬롯에서의 DPCCH의 전력 제어는 상기 전자의 전송 전력 제어 방법을 따른다.The K_used value is a predetermined constant

Can be represented by

If the HS-DPCCH has already been transmitted within the slot, the K_used value is adjusted to the number between the last slot for transmitting the HS-DPCCH and the slot for transmitting the current HS-DPCCH. Power control of the DPCCH in the slot not transmitting the HS-DPCCH follows the electronic transmission power control method.

However, in the conventional transmission power control method, even when signal transmission to the control channel for controlling the downlink shared channel is terminated, the adjusted transmission power is left. Therefore, the transmission power of the general control channel is unnecessarily high for a predetermined time. There was a problem with the transmission.

That is, the transmission power of the DPCCH in the slot for transmitting the HS-DPCCH is increased as necessary, and when the transmission of the DPCCH transmission power returns to the normal transmission power control method in the soft handover state after the transmission of the HS-DPCCH is completed. If the HS-DPCCH is not transmitted again, several slots may be consumed to return to an appropriate level. Therefore, the DPCCH is transmitted with more power than necessary during this slot period, thereby increasing the degree of interference in the system.

Accordingly, an object of the present invention is another uplink control channel that can be received by two or more cell base stations that are adjusted up to help demodulate an uplink control channel for controlling a downlink shared channel provided by one cell in a cellular wireless communication system. The present invention provides a control channel transmission power control method of a wireless communication terminal for quickly recovering a transmission power of a wireless communication terminal.

The control channel transmission power control method of a wireless communication terminal according to the present invention includes a method of controlling a second uplink control channel when a signal is transmitted to a first uplink control channel for controlling a downlink shared channel provided by a cell in a cellular wireless communication system. And a second process of reducing transmission power of a second uplink control channel when signal transmission to the first uplink control channel is terminated. Decreases the transmission power increased for the first uplink control channel.

Another embodiment of a control channel transmission power control method of a wireless communication terminal according to the present invention, in the base station that serves HSDPA at the time when the terminal in the soft handover state starts the HS-DPCCH transmission in the IMT-2000 HSDPA system A first step of increasing the DPCCH transmission power to a predetermined level to facilitate HS-DPCCH reception; A second process of reducing the DPCCH transmission power by the increased level at the end of the HS-DPCCH transmission is described in detail with reference to FIG. 4 to which the transmission power control method of the present invention is attached.

The DPCCH power control method of the present invention uses a conventional transmission power control method in which the terminal in soft handover state properly adjusts the DPCCH transmission power in the HS-DPCCH transmission interval in the IMT-2000 HSDPA system, but the HS-DPCCH transmission At the end of this time, the DPCCH transmit power is adjusted back to the transmit power required for DPCCH transmission in a normal soft handover state so that the DPCCH transmit power is quickly restored to the required level.

만큼 증가시킨다.4 illustrates a method for adjusting power of the DPCCH in the soft handover state proposed by the present invention. In this method, the terminal in the soft handover state transmits the power of the DPCCH in the slot in which the HS-DPCCH is transmitted, as in the conventional method.

Increase by.

만큼 증가시킨다.However, in the present invention, unlike the conventional method, after the terminal finishes the HS-DPCCH transmission, the transmission power of the DPCCH in the first slot is expressed by Equation 3 below.

Increase by.

Here, d is a value for estimating the amount of DPCCH transmission power increase required in the HS-DPCCH transmission slot in the conventional method, TPC_comb (HS_end) represents the TPC_comb value in the slot after the HS-DPCCH transmission as shown in FIG. . Therefore, according to the method proposed by the present invention, the DPCCH transmission power increased by step d at the start of HS-DPCCH transmission is decreased by d at the end of HS-DPCCH transmission. In Equation 3, y is a value for compensating for a power control error that may occur by abruptly reducing the DPCCH transmission power after the HS-DPCCH transmission. This y value can be set in various ways depending on the system implementation.

In b) and c), TPC_comb (HS_start) indicates a TPC_comb value in a slot where HS-DPCCH transmission starts as shown in FIG. 4.

As described above, after adjusting the DPCCH transmit power value in the first slot after HS-DPCCH transmission, the DPCCH transmit power control follows the power control method in a general soft handover state.

Meanwhile, the DPCCH power control method of the present invention considering the transmission interval of the HS-DPCCH will be described below.

When applying the power control method of the present invention to the DPCCH power control, if another HS-DPCCH is transmitted within the K_used slot after one HS-DPCCH is transmitted, the second HS-DPCCH slot is transmitted The distance between two HS-DPCCH transmission slots may be insufficient for estimating additional power required for DPCCH transmission at. In view of this, Equation 3 may be modified and applied to one of two Equations as follows.

First, if the next HS-DPCCH transmission begins after the K_used slot:

Otherwise:

second,

Here, K_intv means a slot interval to the next HS-DPCCH transmission slot, and becomes 0 when the HS-DPCCH is transmitted to the next slot. In addition, f (K_intv) is an arbitrary function that takes K_intv as an argument, and Max {a, b} means the maximum of two values, a and b.

As described in detail above, the present invention provides a second uplink control that can be received by two or more cell base stations to help demodulate a first uplink control channel for controlling a downlink shared channel provided by a cell in a cellular wireless communication system. There is an effect that can be controlled more efficiently the transmission power of the channel.

In particular, in the IMT-2000 HSDPA system, the terminal in the soft handover state adjusts the DPCCH transmission power appropriately in the HS-DPCCH transmission interval, and when the HS-DPCCH transmission ends, the normal soft handover is performed again. By adjusting the transmission power required for DPCCH transmission in the state so that the DPCCH transmission power can be quickly restored to the required level, the uplink DPCCH transmission power of the terminal can be adjusted more efficiently, thereby reducing the degree of uplink interference in the system. It works.

Claims (13)

Adjusting a transmission power of a second uplink control channel when a signal is transmitted to a first uplink control channel for controlling a downlink shared channel provided by a cell in a cellular wireless communication system; When the signal transmission to the first uplink control channel is terminated, reducing the transmit power of the second uplink control channel by the uplinked transmit power again; Wherein the up and down is the control channel transmission power control method of a wireless communication terminal, characterized in that for a time unit consisting of one or more time slots. delete The control channel transmission power control method of claim 1, wherein a power control command for the second uplink control channel is received from two or more base stations. The method of claim 1, wherein the first uplink control channel is an HS-DPCCH of an HSDPA system and the second uplink control channel is a DPCCH. delete 5. The method of claim 4, wherein when the uplinked transmission power level is d + TPC_SC (HS_start), the DPCCH transmission power level is changed at the end of the HS-DPCCH transmission.

Control channel transmission power control method of a wireless communication terminal, characterized in that for reducing. Here, d is an additional power value required for transmitting the DPCCH in the slot in which the HS-DPCCH is transmitted, and the TPC_SC (HS_start) is from a cell serving the HSDPA for the slot in which the HS-DPCCH transmission is started. TPC_comb (HS_end) is a received power control command, and is a power control command obtained using power control commands received from base stations in soft handover for the slot after the HS-DPCCH transmission is completed, and y is any error compensation. It means a value. 7. The control channel transmission power control method of claim 6, wherein the y value is zero. 7. The method of claim 6, wherein the y value is one. 7. The method of claim 6, wherein the y value is TPC_comb (HS_start). The TPC_comb (HS_start) is a power control command obtained by using power control commands received from base stations in soft handover for the slot where the HS-DPCCH transmission is started. 7. The method of claim 6, wherein the y value is TPC_comb [HS_start] +1. The TPC_comb (HS_start) is a power control command obtained by using power control commands received from base stations in soft handover for the slot where the HS-DPCCH transmission is started. The control channel of claim 6, wherein the condition for reducing the transmission power level of the DPCCH is when the next HS-DPCCH transmission is made after a specific number of slots after the current HS-DPCCH transmission is completed. Transmission power control method. The control channel transmission power control method of claim 6, wherein Max {0, d-f (K_intv)} is applied instead of d. Here, K_intv means the number of slots between the end of the current HS-DPCCH transmission start time and the next HS-DPCCH transmission start time, f (K_intv) is an arbitrary function taking K_intv as a factor, Max {a, b } Is the maximum of two values. delete

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