Short TTI Control Region Multiplexing for Latency Reduction
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Solution Overview
Problem
Current wireless communication systems face challenges in reducing latency, particularly in 3G/4G networks, due to inefficient use of radio resources and inability to support varying data packet sizes and latency requirements, leading to wasted resources and unsatisfactory performance in addressing different user equipment (UE) needs.
Innovation Solution
The implementation of short Transmission Time Intervals (TTIs) configured within normal TTI regions, allowing for dynamic resource sharing between downlink control and data, and enabling support for multiple TTI lengths to address diverse latency requirements, along with the use of ultra-low latency alert signals for overriding soft bits and efficient multiplexing of control and data resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the whole control region is reserved for downlink control signaling, then control signaling can be transmitted reliably, but radio resources are wasted and cannot be used for downlink data
Solution Approach 1:
The patent merges the control region and data region by allowing downlink data to be transmitted in resources originally reserved for control signaling. The control channel and data channel share the same time-frequency resources through multiplexing techniques, eliminating the need for separate reserved control regions while maintaining both control signaling reliability and data transmission efficiency.
Solution Approach 2:
The patent makes the control region multi-functional by enabling it to serve both control signaling transmission and downlink data transmission. The same radio resources can dynamically accommodate either control or data traffic based on instantaneous network conditions, increasing resource utilization flexibility and reducing waste.
2Device complexity
If only one TTI length is supported at any given time, then system complexity is reduced, but the network cannot address different latency requirements of different UEs satisfactorily
Solution Approach 1:
The patent introduces dynamic TTI length adjustment capabilities, allowing the system to flexibly change TTI durations based on traffic conditions and UE requirements. The network can dynamically select between short TTIs for low-latency services and normal TTIs for regular traffic, providing adaptability without requiring completely separate system configurations for each TTI type.
Solution Approach 2:
The patent changes the TTI length parameter dynamically to match different service requirements. By adjusting the TTI duration parameter based on latency needs, the system can optimize performance for both low-latency and normal-latency applications using a unified framework, avoiding the complexity of multiple fixed TTI systems.
3Loss of time
If short TTIs are used to reduce latency, then end-to-end latency is reduced and user experience is improved, but resource allocation becomes more complex and control overhead increases
Solution Approach 1:
The patent segments the resource allocation process into manageable units by introducing standardized short TTI structures with predefined formats for control channels and data channels. This segmentation allows the complex resource allocation problem to be broken down into smaller, more manageable sub-problems that can be solved using systematic approaches, reducing overall allocation complexity despite the shorter time scales involved.
Data Source
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AI summary
Methods and apparatus are provided for control overhead reduction. The UE configures one or more short transmission time interval regions over a normal TTI region shared by the UE and one or more other, each UE includes a self-contained control information sPDCCH occupying a control information region. The UE detects a cover signal, which indicates one or more resource elements in the sPDCCH control-information region that can be used for data transmission. The UE obtains data transmission from the REs in the SPDCCH control information region based on the detected cover signal. In one embodiment, the cover signal is a dedicated signal. In another embodiment, the cover signal is a common signal. In yet another embodiment, the cover signal is encoded in a downlink control information (DCI) intended for the UE. In one embodiment, the cover signal indicates one or more CCE REs to be excluded for data transmission.