C-RAN Transmit Power Control Using Pre-IRC SINR

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Solution Overview

Problem

Conventional transmit power control in centralized radio access networks (C-RAN) does not account for gains from interference rejection combining (IRC) and introduces errors in signal-to-noise-plus-interference (SINR) estimation, leading to inefficient power usage and increased interference.

Innovation Solution

The system employs pre-IRC SINR for transmit power control, modifying decisions based on the count of consecutive uplink transmissions meeting specific criteria to account for IRC gains and correct for SINR estimation inaccuracies, ensuring UEs transmit at the optimal power level for maximum throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional transmit power control is used in C-RAN, then the system operates with standard power control mechanisms, but it does not account for IRC gains leading to inefficient power usage and increased interference

Engineering Contradiction:

Improvepower usage efficiencyVSAvoidinterference

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the controller receives IRC gain information from the radio points and uses this feedback to adjust transmit power control commands. The controller modifies TPC commands based on measured IRC gains, creating a closed-loop system that adapts power control to actual interference rejection performance, thereby improving power efficiency and reducing unnecessary interference.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameter used for power control by incorporating IRC gain measurements into the TPC decision process. Instead of using only conventional SINR metrics, the system adjusts power control parameters based on actual IRC performance, allowing dynamic adaptation of transmit power to match the effective interference rejection capability of the system.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional SINR estimation is used for TPC, then the estimation process is simple, but errors and inaccuracies are introduced especially when UEs transmit in the presence of interference

Engineering Contradiction:

ImproveSINR estimation accuracyVSAvoidestimation process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing IRC processing and SINR estimation in a specific sequence where interference rejection is established before accurate SINR measurement. The system first processes signals through IRC to reject interference, then estimates SINR based on the already-cleaned signal, ensuring accurate measurements without requiring complex simultaneous processing of interference and signal components.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If UEs transmit at higher power to ensure throughput, then full throughput can be maintained, but unnecessary power consumption and battery drain increase

Engineering Contradiction:

ImprovethroughputVSAvoidbattery drain

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent implements dynamic transmit power control where the TPC commands are continuously adjusted based on real-time IRC gain measurements. This dynamic approach allows the system to optimize the balance between throughput and power consumption by adapting power levels to current channel conditions and interference rejection effectiveness, preventing both excessive power usage and throughput degradation.

Inventive Principle:

Principle #15Dynamics

4Reliability

If IRC is performed at the C-RAN, then interference rejection gains are achieved, but conventional TPC does not account for these gains

Engineering Contradiction:

Improveinterference rejectionVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the control system multi-functional by having the controller perform both IRC gain measurement and TPC command generation in an integrated manner. The same controller that manages IRC operations also uses the measured gains to optimize power control, eliminating the need for separate specialized systems and reducing overall control complexity while maintaining interference rejection reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11019574B2Transmit power control in a C-RAN

Publication Date: 2021.05.25 OUTDOOR WIRELESS NETWORKS LLC

AI summary

A communication system is provided. The communication system includes at least one radio point, each configured to exchange radio frequency (RF) signals with a user equipment (UE) at a site. The communication system also includes a controller communicatively coupled to the at least one radio point. The controller is configured to determine a transmit power control (TPC) command for the UE based on a signal to interference plus noise (SINK) for the UE. The controller is also configured to determine a count (N) of consecutive uplink transmissions, from the UE, meeting at least one criteria. The controller is also configured to determine a modified TPC command for the UE based on the count (N) and the TPC command.