Cell Reselection Priority Broadcasting for Load Balanced Networks
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Solution Overview
Problem
In LTE radio access networks, maintaining balanced traffic load between multiple carrier frequencies is challenging due to random UE distribution and differences in coverage and capacity, leading to inefficient use of network resources and recurring handovers to correct load imbalances.
Innovation Solution
A method and radio network node configuration that prioritizes cell reselection to intra-frequency options by broadcasting higher cell reselection priorities for the current carrier frequency over others, ensuring UEs primarily perform intra-frequency cell reselection, thereby preserving the balanced distribution achieved in connected mode and reducing the need for inter-frequency handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inter-frequency cell reselection is allowed with equal priorities, then UE can access multiple carrier frequencies, but load balancing between frequencies becomes difficult to maintain
Solution Approach 1:
The patent applies local quality by assigning different cell reselection priorities to different carrier frequencies based on local load conditions. Each cell broadcasts its own load state, and UEs use this local information to make reselection decisions, thereby maintaining load balancing while allowing access to multiple frequencies.
Solution Approach 2:
The patent implements feedback mechanisms where cells transmit their load state information to UEs through system information blocks. This feedback loop enables UEs to adapt their cell reselection behavior based on real-time network conditions, maintaining load balance dynamically.
2Ease of operation
If UE performs autonomous cell reselection based on signal strength, then UE mobility is efficient, but recurring handovers are needed to correct load imbalances
Solution Approach 1:
The patent changes the parameter used for cell reselection from purely signal strength-based to a composite metric that includes both signal strength and cell load state. This parameter change enables UEs to make more informed reselection decisions that balance mobility efficiency with network resource utilization.
Solution Approach 2:
The patent applies preliminary action by having cells broadcast their load state information in advance through system information blocks. This allows UEs to prepare for load-balanced reselection decisions before actual handovers occur, reducing the need for corrective handovers.
3Reliability
If inter-frequency handovers are used to balance load, then traffic distribution improves, but signaling load increases
Solution Approach 1:
The patent applies self-service by enabling UEs to autonomously make cell reselection decisions based on broadcasted load information. This eliminates the need for continuous network-controlled handovers, reducing signaling load while maintaining effective load balancing.
Solution Approach 2:
The patent uses partial action by having cells broadcast only essential load state information rather than complete network state. This provides sufficient information for UEs to make informed reselection decisions without overwhelming the signaling channel with excessive data.
Data Source
AI summary
The present invention relates to a method in a RN node of a communications system operating on multiple carrier frequencies. The RN node hosts a first cell operating on a first carrier frequency and a second cell overlapping with the first cell and operating on a second carrier frequency. The method comprises broadcasting (501) information comprising a cell reselection priority for each of the first and the second carrier frequency in the first cell, where the priority of the first carrier frequency is the highest. The method also comprises broadcasting (502) information comprising a cell reselection priority for each of the first and the second carrier frequency in the second cell, where the cell reselection priority of the second carrier frequency is the highest. Thereby a UE will primarily perform intra-frequency cell reselection.