CIP Algorithm for Cellular Network Load Balancing
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Solution Overview
Problem
Existing Network Load Balancing (NLB) algorithms in 1x Evolved-Data Optimized (1x-EV-DO) networks degrade over-the-air connectivity Key Performance Indicators (KPIs) by forcing Access Terminals (ATs) to less optimal sectors, strain call processing entities with periodic Route Update reports, and may adversely affect Signal-to-Noise Ratio (SNR) and Quality of Service (QoS) without adequate metrics.
Innovation Solution
The Connection Integrity Preservation (CIP) algorithm runs on top of the NLB algorithm to minimize connectivity degradations by ensuring safe offload decisions, optimizing Route Update messaging, and preventing repetitive offloads, while considering previous failure histories and sector availability to maintain connection integrity and SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the NLB algorithm forces ATs to less loaded sectors, then traffic load is balanced and network capacity is improved, but connection loss statistics and KPIs are degraded
Solution Approach 1:
The system performs preliminary evaluation of target sector suitability before forcing AT offload. The RNC assesses whether target sectors can adequately support the AT based on current load conditions and signal quality, and only then unlocks the DRCLock bit to permit sector switching. This prevents premature offloads that would cause connection losses.
Solution Approach 2:
The system continuously monitors connection KPIs and AT performance metrics to dynamically adjust offload decisions. When connection loss rates increase or signal quality degrades, the RNC modifies its offload behavior by being more selective about which ATs are offloaded and to which sectors, ensuring reliability is maintained while still achieving load balancing.
2Measurement precision
If periodic Route Update reports are solicited from ATs, then the NLB algorithm can gauge current RF signal quality, but call processing strain on the RNC increases
Solution Approach 1:
The RNC sends Route Update Request messages to ATs at periodic intervals to obtain current RF signal quality measurements. This periodic sampling provides the NLB algorithm with up-to-date information about forward link pilot strengths without requiring continuous reporting, thereby balancing measurement accuracy with call processing efficiency.
Solution Approach 2:
The system solicits Route Update reports only from a subset of ATs or at reduced frequency when load balancing conditions are not critical, rather than from all ATs continuously. This partial action approach provides sufficient signal quality information for effective NLB decisions while minimizing the call processing burden on the RNC.
3Productivity
If the NLB algorithm makes frequent offload decisions, then traffic load is dynamically balanced, but connection integrity and SNR are degraded
Solution Approach 1:
Before executing an offload decision, the RNC performs preliminary checks to ensure the target sector is suitable and the offload will not harm connection integrity. The system evaluates signal quality thresholds and sector capacity beforehand, and only proceeds with offload when conditions are favorable, preventing frequent unnecessary sector switches that would degrade SNR and connection stability.
Solution Approach 2:
The system implements protective measures in advance to prevent harmful offload decisions. By establishing minimum signal quality thresholds and evaluating target sector readiness before offload, the RNC prevents actions that would otherwise degrade connection integrity and SNR, thereby allowing more aggressive load balancing without compromising reliability.
Data Source
AI summary
A method and apparatus for controlling a Network Load Balancing (NLB) algorithm that balances a traffic load between multiple downlink (DL) sectors in a cellular telecommunication network. A Connection Integrity Preservation (CIP) algorithm, which runs on top of the NLB algorithm in the Radio Network Controller/Base Station Controller (RNC/BSC), minimizes the risk of degrading network performance due to NLB offload decisions. The CIP algorithm may override an NLB offload decision, for example, if there have been too many offload failures, there are no target DL sectors available to acquire an offloaded Access Terminal (AT), or the offloaded AT is not acquired within a threshold time period. The CIP algorithm ensures required metrics are collected, and minimizes the impact on RNC/BSC processing due to Routing Update messages needed to make offload decisions. The invention enables the NLB algorithm to realize its potential without negative side-effects.