LTE TDD eIMTA Power Control Interference Management
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Solution Overview
Problem
Current LTE TDD systems face challenges in managing interference between uplink and downlink subframes, leading to inefficient power control and performance degradation due to eNB-to-eNB and UE-to-UE interference, particularly in UL-DL coexistence scenarios.
Innovation Solution
The method involves determining the interference type between a serving cell and a neighboring cell's TDD configuration subframes and adjusting transmit power accordingly, using open loop and closed loop power control techniques to set optimal UL and DL transmit powers for UE and eNB, respectively, by categorizing subframes into anchor and non-anchor types and applying specific power control parameters based on coexistence conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If full power DL transmission is used in TDD subframes, then downlink coverage and capacity are improved, but uplink performance deteriorates due to eNB-to-eNB and UE-to-UE interference
Solution Approach 1:
The patent applies different power control strategies to different subframe types (anchor vs. non-anchor) and different interference scenarios (UL-UL coexistence vs. UL-DL coexistence). Specifically, in UL-DL coexistence subframes where the serving cell is in UL and neighboring cell is in DL, the eNB adjusts DL transmit power to minimize interference to uplink, while in UL-UL coexistence subframes, full power transmission can be used. This localized differentiation resolves the contradiction by applying power control only where interference occurs.
Solution Approach 2:
The patent implements dynamic power adjustment based on real-time interference conditions. The eNB determines the interference type for each subframe and dynamically sets DL transmit power accordingly - using full power when interference is not an issue and reduced power when UL-DL coexistence creates interference. This dynamic adaptation allows the system to maintain high DL power when possible while protecting UL performance when needed.
2Reliability
If power control parameters are adjusted to reduce interference, then uplink performance is improved, but downlink power efficiency deteriorates
Solution Approach 1:
The patent segments subframes into anchor subframes and non-anchor subframes, and further segments them by interference type (UL-UL coexistence vs. UL-DL coexistence). This segmentation allows the system to apply power control adjustments only in specific subframes where interference occurs, rather than uniformly across all subframes. Consequently, DL power efficiency is maintained in subframes where full power can be used, while UL reliability is protected in subframes requiring power adjustment.
Solution Approach 2:
The patent changes power control parameters (PO_NOMINAL_PUSCH, PO_UE_PUSCH, alpha) based on interference type and subframe category. By adjusting these parameters dynamically - using conservative values in UL-DL coexistence subframes and standard values in other subframes - the system achieves UL performance improvement only where necessary, minimizing overall power loss while maintaining energy efficiency in non-interfering subframes.
3Reliability
If separate power control loops are implemented for anchor and non-anchor subframes, then interference management is improved, but system complexity increases
Solution Approach 1:
The patent uses a unified power control framework that handles both anchor and non-anchor subframes through common mechanisms. The eNB determines interference type and applies appropriate power control parameters from standardized sets, rather than implementing completely separate control loops. This universal approach simplifies the system while still providing differentiated power control for different subframe types and interference scenarios.
Solution Approach 2:
Instead of creating complex separate control loops, the patent manages interference by changing power control parameters (PO values, alpha values) based on subframe type and interference condition. This parameter-based approach achieves effective interference management through a relatively simple mechanism - selecting from predefined parameter sets based on the determined interference type, thereby avoiding the need for complex separate control architectures.
Data Source
AI summary
A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus determines an interference type between a time division duplex (TDD) configuration subframe of a serving cell and a corresponding TDD configuration subframe of a neighboring cell, and sets a transmit power for an apparatus in the serving cell based on the interference type. The apparatus in the serving cell may be a user equipment (UE), in which case the apparatus applies a set of uplink (UL) open loop power control parameters for the UE. The apparatus in the serving cell may be a base station (eNB), in which case a DL transmit power is set for the eNB. Depending on the interference type, the DL transmit power may be a fixed, full power DL transmission or an adjusted DL transmission.