Radio Network Controller TTI Switching Control
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Solution Overview
Problem
Current wireless communication systems face challenges in managing transmission time interval (TTI) switching, particularly in third-generation networks, where the Radio Network Controller (RNC) lacks control over the number of users on 2 ms and 10 ms TTIs, leading to inefficient resource management and reduced coverage for shorter TTIs.
Innovation Solution
Implementing a method where the Radio Base Station (NodeB) autonomously decides TTI switches and communicates with the RNC to request and manage TTI changes, ensuring proper configuration and resource allocation for both 2 ms and 10 ms TTIs, allowing the RNC to maintain control over user distribution on each TTI type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the RNC autonomously controls TTI switching decisions, then resource management and user distribution control are improved, but TTI switch response time and reconfiguration speed deteriorate
Solution Approach 1:
The patent segments the TTI switching control function by introducing an intermediate entity (the base station or eNodeB) that autonomously makes TTI switching decisions for individual users at the radio interface level, while the RNC retains overall resource management authority. This segmentation allows fast local decisions without requiring full RNC intervention for each switch, thus reducing response time while maintaining centralized resource control.
Solution Approach 2:
The base station acts as an intermediary between the RNC and the wireless communication device regarding TTI switching. The base station receives resource allocation instructions from the RNC and autonomously executes TTI switching decisions based on local channel conditions and user requirements, mediating between centralized resource management and distributed fast switching needs.
2Loss of time
If the TTI is shortened to reduce latency, then end-user experience for mobile broadband services is improved, but coverage area and robustness in poor channel conditions deteriorate
Solution Approach 1:
The patent implements dynamic TTI length adjustment where the TTI duration is not fixed but can be changed based on channel conditions, user location, and service requirements. Users in good channel conditions or near the cell center can use short TTIs (e.g., 2 ms) for low latency, while users approaching cell boundaries or in poor conditions automatically switch to longer TTIs (e.g., 10 ms) for better robustness, creating a dynamic adaptation to varying conditions.
Solution Approach 2:
Different TTI lengths are applied locally to different users or different spatial regions within the cell based on their specific channel conditions. Instead of using a uniform TTI for the entire cell, the system allows short TTIs in favorable local conditions and long TTIs in unfavorable local conditions, optimizing performance for each local situation.
3Productivity
If the RNC maintains full control over TTI switching, then centralized resource allocation is improved, but system complexity and control signaling overhead increase
Solution Approach 1:
The patent extracts the specific TTI switching decision function from the RNC and relocates it to the base station. The RNC retains control over overall resource allocation and user admission, but the detailed TTI switching decisions are taken out and made locally at the base station, reducing the control burden and complexity at the RNC while maintaining centralized resource management principles.
Data Source
AI summary
A radio network controller, RNC, keeps control of how many users to configure on a first transmission time interval, TTI, and how many to configure on a second TTI. For example, a method, performed by the RNC, for configuring at least one radio bearer between a radio base station, RBS, and wireless communication devices. The method comprises receiving, from the RBS, a request to perform a TTI switch according to a TTI switch trigger received by the RBS. The received request is analyzed and a grant to perform the requested TTI switch is sent to the RBS.