Mobile User Equipment Transmit Power Control During CDMA Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems like WCDMA, handover messages often fail to be received correctly due to delays and power control issues, leading to dropped calls, especially in high-speed scenarios where signal strength is weak.
Innovation Solution
The mobile user equipment temporarily overrides power control commands to increase transmit power during handover message transmission, ensuring the message is sent at a higher power level and then returns to normal operation, and optionally increases the target Signal-to-Interference Ratio (SIR) to enhance reception reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power control commands are followed to maintain low transmit power, then energy consumption is reduced and interference is minimized, but handover message transmission reliability deteriorates in weak signal conditions
Solution Approach 1:
The transmit power is dynamically adjusted based on the transmission state. During normal operation, power control commands are followed to maintain low power. During handover message transmission, the power is temporarily increased to ensure reliable delivery. This dynamic switching between power levels resolves the contradiction between energy efficiency and transmission reliability.
Solution Approach 2:
The mobile station determines in advance whether a message requires handover before transmission. Based on this preliminary determination, the transmit power is pre-adjusted to an appropriate level. This preliminary action ensures that the power is already optimized when the handover message is transmitted, preventing transmission failures without wasting energy on unnecessary power increases.
2Reliability
If transmit power is increased during handover message transmission, then message delivery reliability is improved, but energy consumption and interference increase
Solution Approach 1:
The increased transmit power is applied locally and selectively only during handover message transmission, not during all communications. The mobile station identifies when handover messages need to be sent and increases power only for those specific transmissions. This localized application of high power minimizes overall energy consumption while ensuring reliability when needed.
Solution Approach 2:
The transmit power is periodically adjusted based on the transmission of handover messages. Instead of maintaining high power continuously, the system switches to high power only during the periodic moments when handover messages are transmitted, then returns to normal power control. This periodic action reduces energy consumption compared to continuous high power while ensuring message reliability.
3Productivity
If power control is maintained during handover, then normal power management is preserved, but handover message errors increase leading to more retransmissions
Solution Approach 1:
The power control strategy dynamically switches between normal power control and increased power mode based on the message type. For regular messages, normal power control efficiency is maintained. For handover messages, the system transitions to increased power mode to ensure accurate transmission. This dynamic adaptation resolves the contradiction between power control efficiency and message accuracy.
Solution Approach 2:
The transmit power parameter is changed specifically for handover message transmission. The system modifies the power parameter from its normal controlled value to a higher value when handover messages are detected. This parameter change ensures that handover messages are transmitted with sufficient power for accurate reception, reducing errors and retransmissions while maintaining normal power control for other communications.
Data Source
AI summary
A method and device for controlling a mobile user equipment being in radio communication with base stations of a wireless communication system. The transmit power of the user equipment is controlled by the communication system. Immediately before sending an event message by the user equipment, the transmit power is increased by the user equipment, in order to increase the likelihood that the message is properly received by the base station. The message may be a soft handover event message. The transmit power is increased by opening a closed loop power control circuit, which normally controls the transmit power of the user equipment. By opening the closed loop circuit, the user equipment takes over the control of its transmitted power for increase thereof. Following the sending of the message, the user equipment may control the base station to send with increased power by increasing a target signal-to-interference ratio value (SIRref) by means of which the base station power level is controlled. In this way, the likelihood of receiving any acknowledgement messages and event messages from the base station is increased.