Shortened-TTI Channel Allocation for Mixed LTE User Equipment
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Solution Overview
Problem
The LTE or LTE-A system needs to define downlink and uplink physical channels and HARQ transmission schemes for a transmission time interval (TTI) less than 1ms to support both regular and shortened-TTI user equipments (UEs) in the same system.
Innovation Solution
The method involves determining UE type, generating control information based on first type UE, allocating resource blocks, and configuring channels like PDCCH, EPDCCH, PDSCH, PHICH, PUCCH, and PUSCH for shortened-TTI UEs, with HARQ transmission methods adapted for both downlink and uplink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the system supports both regular TTI (1ms) and shortened-TTI (less than 1ms) UEs simultaneously, then the adaptability and versatility of the system is improved, but the device complexity and system configuration complexity increases
Solution Approach 1:
The system segments UEs into different types (first type UE for shortened-TTI, second type UE for regular TTI) and configures separate physical channels and HARQ transmission schemes for each type. This segmentation allows the system to support multiple TTI lengths without requiring complete system redesign, thereby improving adaptability while managing complexity through structured division.
Solution Approach 2:
The system dynamically adapts physical channel configurations and HARQ parameters based on UE type. The base station can flexibly switch between different TTI lengths and corresponding channel structures depending on service requirements, enabling the system to respond to varying latency demands while maintaining operational simplicity through standardized adaptation mechanisms.
2Speed
If the transmission time interval is shortened to support latency-critical services, then the speed and responsiveness of the system is improved, but the reliability of data transmission may deteriorate due to reduced processing time
Solution Approach 1:
The system changes key parameters including TTI length, physical channel structure, and HARQ timing relationships specifically for first type UEs. By optimizing these parameters for shortened-TTI operation, the system achieves lower latency while maintaining adequate processing margins through parameter sets designed specifically for fast transmission scenarios.
Solution Approach 2:
The system performs preliminary configuration of physical channels and HARQ parameters before actual data transmission. The base station pre-configures appropriate TTI lengths, channel structures, and timing relationships for first type UEs, ensuring that all necessary processing is prepared in advance to maintain reliability even with shortened transmission intervals.
3Productivity
If separate physical channels and HARQ schemes are defined for shortened-TTI UEs, then the productivity and efficiency of latency-critical services is improved, but the loss of information and system overhead increases
Solution Approach 1:
The system designs physical channels and HARQ schemes that serve multiple functions: they support both regular TTI and shortened-TTI operations through configurable parameters, and handle both data transmission and control signaling within unified channel structures. This multi-functionality reduces the need for completely separate channel definitions, thereby limiting information overhead while maintaining high service efficiency for latency-critical applications.
Data Source
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AI summary
The present disclosure relates to 5G or pre-5G communication systems supporting higher data rates after 4G communication systems like the LTE system. Specifically, the present invention relates to a wireless communication system and, more particularly, to a method and apparatus for carrying out downlink and uplink control channel transmissions in a system supporting transmission and reception with a transmission time interval of less than 1ms. Specifically, the present invention provides definitions for physical channels needed for transmission and reception with a transmission time interval of less than 1ms, and a method for resource allocation and resource block mapping.