Method and system for controlling downlink transmission power

Abstract

The invention discloses a method for controlling a downlink transmission power, a minimum receiving code power level Qrxpwrmin and a signal-inference ratio target value SIRtarget are set in an user equipment UE and a minor minimum downlink transmission power Minimum DL Power is set in the base station, if the SIR measuring value SIRmeas measured by the UE is larger than the SIRtarget and the code power level Qrxpwr received by the UE is larger than the Qrxprmin, so that the base station is indicated to reduce the downlink transmission power, the base station can judge the present transmission Current DL Power and the Minimum DL Power based on the indication and correspondingly reduces or maintains downlink based on the judging results, because the set Minimum DL Power value is smaller, thereby saving the system power resource; if the SIRmeas measured by the UE is smaller than the SIRtarget or the Qrxpwr received by the UE is smaller than the Qrxpwrmin, the base station is indicated to improve the downlink transmission power, thus when the UE is positioned on a district edge, the Qrxpwr received by the UE can be ensured, the Dropped Call Rate can be reduced when the UE is positioned in a declined or a depth declined area. The invention also discloses a system for controlling downlink transmission power.

Description

technical field [0001] The present invention relates to power control technology, in particular to a method and system for controlling downlink transmission power. Background technique [0002] In a Time Division Synchronous Code Division Multiple Access / Wideband Code Division Multiple Access (TD-SCDMA / WCDMA, TimeDivision-Synchronous Code Division Multiple Access / Wideband Code Division Multiple Access) system, a single channel of a single user equipment (UE, User Equipment) is In other words, the downlink power transmitted by the base station (Node B) to it is controlled within the range between the preset minimum downlink transmission power (Minimum_DL_Power) and the maximum downlink transmission power (Maximum_DL_Power) dB. [0003] Wherein, the values ​​of Minimum_DL_Power and Maximum_DL_Power can be set by high layers. [0004] When the Node B enters the closed-loop power control (Closed-Loop Power Control) mode, the UE generates a transmit power control (TPC, Transmiss...

AI Technical Summary

Problems solved by technology

But in practice, the minimum downlink transmit power of Node B is set based on the cell edge UE. When Node B adjusts the downlink transmit power to Minimum_DL_Power, the downlink transmit power cannot be reduced any more, resulting in a waste of system power resources.

[0021] However, if the Minimum_DL_Power value set in Node B is too small, when the UE is at the edge of the cell, its channel quality may still be in a good state. For example, when the received signal is weak but the noise is small, the measured SIRmeas It can still be no less than SIRtarget. According to the aforementioned method, it indicates that the channel quality is good, and Node B can maintain a lower downlink transmission power. However, if the UE enters a fading or deep fading area for a period of time, due to the received The signal is weak, and the path loss in the fading area is large, which may cause the UE to fail to receive the signal and lose contact with Node B, resulting in call drop

[0022] Therefore, in the prior art, when the UE enters the closed-loop power control, the UE estimates the current channel quality by measuring the SIR and controls the downlink transmission power of the Node B. In the fading or deep fading area at the edge of the cell, it may cause call drop; and if the Minimum_DL_Power set by Node B is too large, it will lead to waste of system power resources

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