Inter-eNB Coordination for LTE Transmission Power Control
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Solution Overview
Problem
In the 'Inter-eNB CA' scenario of the LTE system, radio base stations lack complete comprehension of the transmission power status of mobile stations under their control due to unknown variables like resource blocks, propagation loss, and power control values, making accurate transmission power estimation and control challenging.
Innovation Solution
Each radio base station reduces the transmission power of mobile stations by a predetermined amount and notifies other base stations, allowing for coordinated power control without relying on backhaul communication, thereby avoiding propagation delays and enabling effective power management across multiple cell networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If independent scheduling control and transmission power control are performed at each radio base station in Inter-eNB CA, then each base station can autonomously manage its cell, but complete comprehension of mobile station transmission power status cannot be achieved
Solution Approach 1:
The patent implements feedback mechanisms where mobile stations report power headroom information to serving base stations, and base stations exchange transmission power control information through backhaul connections. This feedback loop enables each base station to gradually comprehend the overall transmission power status of mobile stations across multiple cells, resolving the information loss problem while maintaining autonomous control capabilities.
Solution Approach 2:
The patent divides the transmission power control system into segmented functional modules: mobile station power measurement units, base station power calculation units, and inter-base station communication units. Each segment handles specific aspects of power control independently yet cooperatively, allowing autonomous operation at each base station while collectively achieving complete power status comprehension through standardized information exchange protocols.
2Loss of information
If backhaul communication is used for power control coordination between base stations, then complete power status information can be exchanged, but propagation delays of tens of microseconds occur
Solution Approach 1:
The patent implements preliminary action by having mobile stations continuously measure and report power headroom information to their serving base stations before actual power control decisions are made. Base stations pre-calculate transmission power control values and exchange this information through backhaul connections in advance, reducing the impact of propagation delays during actual power control execution and enabling faster response times.
3Reliability
If transmission power is reduced by predetermined amount without coordinated control, then power ceiling attainment can be prevented, but excessive power reduction and inefficient power utilization occur
Solution Approach 1:
The patent employs feedback mechanisms where mobile stations report power headroom information indicating their proximity to power ceiling limits. Base stations use this feedback to calculate appropriate power control values that prevent power ceiling attainment while avoiding excessive power reduction. The system continuously adjusts transmission power based on real-time feedback, maintaining optimal power utilization efficiency while ensuring reliable power ceiling prevention.
Data Source
AI summary
An object is to appropriately perform transmission power control on a mobile station (UE) when performing “Inter-eNB CA” by using cells under the control of plural radio base stations (eNB). In a mobile communication system according to the present invention, each of plural radio base stations (eNB #1, eNB #2) reduces, upon detecting that the mobile station (UE) is performing transmission at a maximum transmission power (PCMAX,c), by a predetermined amount a transmission power of the mobile station (UE) in a cell (#1/#2A to #2C) under the control thereof and notifies other radio base station (eNB) of the predetermined amount.