Inter-gNB Carrier Aggregation Congestion Control
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Solution Overview
Problem
Current carrier aggregation techniques in wireless networks face challenges with non-collocated nodes, large inter-node delays, numerology differences, and mesh relationships, leading to inefficiencies and reduced quality of service, especially when performing CA between high-bandwidth/high-frequency and low-bandwidth/low-frequency carriers.
Innovation Solution
The solution decouples PCELL and SCELL scheduling decisions using semi-static HARQ codebooks or separating HARQ feedback opportunities into virtual PUCCH groups, and employs a congestion control algorithm to manage multiple flows from multiple partners, allowing for flexible and efficient resource allocation across gNBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carrier aggregation is performed between high-bandwidth/high-frequency and low-bandwidth/low-frequency carriers hosted in different gNBs, then network capacity and bandwidth are improved, but inter-node delay and scheduling coordination complexity increase
Solution Approach 1:
The patent segments the carrier aggregation system into independent scheduling domains. Each gNB autonomously schedules its own carriers without requiring centralized coordination, dividing the scheduling function into distributed segments that operate independently. This eliminates the need for complex inter-node scheduling coordination while maintaining carrier aggregation functionality across multiple gNBs.
Solution Approach 2:
The patent introduces a new dimension of operation by allowing different numerologies (subcarrier spacings, slot durations) to coexist across carriers from different gNBs. Instead of requiring uniform scheduling parameters across all carriers, the system accepts and manages dimensional diversity in numerology, enabling flexible carrier aggregation between high-frequency and low-frequency carriers with different timing characteristics.
2Device complexity
If centralized scheduler controls scheduling decisions across all serving cells, then coordination is simplified, but inter-node communication overhead and delay increase
Solution Approach 1:
The patent extracts the scheduling function from the centralized controller and relocates it to the individual gNBs. Each gNB independently performs scheduling decisions for its own carriers, removing the need for continuous inter-node communication for scheduling coordination. This extraction eliminates the communication overhead and delay associated with centralized scheduling while maintaining coordination through standard backhaul interfaces.
3Productivity
If MAC flow packet size is scaled based on carrier bandwidth, then spectrum usage efficiency is improved, but complexity of managing multiple flows from multiple partners increases
Solution Approach 1:
The patent implements self-service mechanisms where each gNB autonomously manages its own MAC flows and makes independent scheduling decisions. The congestion control algorithm operates in a distributed manner, with each node adapting its own flow rates based on local conditions and feedback. This eliminates the need for a central entity to manage all flows, reducing flow management complexity while maintaining spectrum efficiency through bandwidth-proportional packet sizing.
Solution Approach 2:
The patent employs feedback-based congestion control where each gNB monitors its own queue states and adjusts MAC flow rates accordingly. The congestion control algorithm uses local feedback information about buffer occupancy and channel conditions to dynamically scale packet sizes and flow rates, enabling efficient spectrum usage without requiring complex centralized flow management.
Data Source
AI summary
A method, network node, computer program, and computer program product are provided. A number of media access control, MAC, flows from the first network node that each forms a source end-point to a destination end-point is defined, wherein the first network node includes the source end-point and each destination end point node includes a second network node having one or more destination carriers. A MAC flow packet size is defined that is scaled based on carrier bandwidth where each MAC flow packet has an approximately equivalent spectrum usage and an equivalent quality of service, QoS, on a destination carrier on the second network node. A MAC flow packet is transmitted to the second network node, wherein the MAC flow packet node includes a bundle of one or more MAC sub-protocol data units, sub-PDUs.