Shortened TTI Control Channel Resource Mapping
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Solution Overview
Problem
3GPP LTE systems face challenges in reducing packet data latency, which affects responsiveness and throughput, particularly due to the fixed transmission time interval (TTI) length of 1 millisecond, leading to inefficiencies in signaling overhead and processing time.
Innovation Solution
The implementation of a shortened transmission time interval (S-TTI) with 2 or 3 symbols, allowing for flexible resource allocation and reduced control signaling overhead, while maintaining scheduling flexibility through localized and distributed S-PDCCH resource mapping, and optimizing blind decoding attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a fixed transmission time interval (TTI) length of 1 millisecond is used, then system stability is maintained, but packet data latency increases and responsiveness deteriorates
Solution Approach 1:
The patent implements dynamic TTI length adaptation, allowing the system to switch between different TTI durations (e.g., 1ms, 0.5ms, or shorter) based on traffic conditions and service requirements. This enables the system to reduce latency for time-sensitive applications while maintaining stability for conventional traffic, directly resolving the contradiction between fixed TTI stability and latency reduction.
Solution Approach 2:
The invention changes the time parameter of TTI from a fixed value to a variable parameter that can be adjusted according to different service types and channel conditions. By modifying this fundamental parameter, the system achieves both low latency for urgent data and maintained stability for regular operations, eliminating the trade-off between responsiveness and system stability.
2Loss of time
If shortened transmission time interval (S-TTI) is implemented, then packet data latency is reduced, but control signaling overhead increases
Solution Approach 1:
The patent segments control signaling into different types and priorities, allowing selective transmission of essential control information during S-TTI periods. By dividing control signaling into critical and non-critical components, the system reduces overall overhead while maintaining the shortened transmission time benefits for data traffic.
Solution Approach 2:
The invention applies partial action by transmitting only the necessary control signaling during S-TTI periods rather than full control overhead. This selective approach maintains the reduced transmission time advantage while minimizing the increase in control signaling burden on the system.
3Productivity
If flexible resource allocation is implemented, then spectrum efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements local quality by applying different resource allocation strategies to different frequency resources and time slots based on channel conditions and service requirements. This localized approach optimizes spectrum efficiency in specific regions where needed while using simpler allocation methods elsewhere, reducing overall device complexity.
Solution Approach 2:
The invention introduces dynamic resource allocation that adapts to changing channel conditions and traffic patterns. By making resource allocation flexible and condition-dependent rather than static, the system achieves improved spectrum efficiency without requiring overly complex allocation algorithms, as the complexity is activated only when conditions warrant optimization.
Data Source
AI summary
Technology for a user equipment (UE) operable to identify downlink control channel candidates for receiving downlink control channel information is disclosed. The UE can decode a downlink control information (DCI) format received from an eNodeB. The DCI format can indicate a set of resource blocks (RBs) in one or more subframes allocated for reception or transmission of data or control information in a shortened transmission time interval (S-TTI). The UE can identify a subset of resource elements (REs) within the set of RBs in the one or more subframes. The subset of REs can correspond to shortened physical downlink control channel (S-PDCCH) candidates in the S-TTI of one or more subframes. The UE can attempt to decode the S-PDCCH candidates in the S-TTI of the one or more subframes. S-PDCCH candidates that are successfully decoded can cause the UE to identify the downlink control information.