Base Station sTTI Timing Configuration for Asymmetric DL UL Latency
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Solution Overview
Problem
In traditional LTE/LTE Advanced systems, the shortening of Transmission Time Interval (TTI) lengths for downlink (DL) and uplink (UL) signals results in differing sTTI lengths, necessitating the redefinition of data assignment, transmission, reception, and feedback timings.
Innovation Solution
A base station and terminal configuration that includes separate short transmission time intervals (sTTIs) for DL and UL, with the reception section receiving uplink signals in the second sTTI positioned after a predetermined interval from the transmission timing of the downlink signal, based on the length of the first sTTI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the TTI length is shortened to reduce latency, then the latency for CQI reporting is reduced and the frequency of CQI reporting is increased, but the TTI lengths for downlink and uplink become different, requiring redefinition of data assignment, transmission, reception, and feedback timings
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the TTI length independently for downlink and uplink directions. The base station can configure different sTTI lengths (e.g., 2, 3, or 4 OFDM symbols) for DL and UL based on channel conditions and service requirements, resolving the contradiction by allowing latency reduction while managing timing complexity through flexible parameter configuration
Solution Approach 2:
The patent implements dynamics by enabling the TTI length to be dynamically changed between downlink and uplink directions. The system can switch between different sTTI configurations (e.g., DL sTTI of 2 symbols and UL sTTI of 4 symbols) based on real-time requirements, allowing the system to adapt to varying latency needs while maintaining proper timing relationships through dynamic reconfiguration
2Productivity
If separate sTTI lengths are used for downlink and uplink, then communication efficiency is enhanced and latency is reduced, but the timings of data assignment, transmission, reception, and feedback must be redefined
Solution Approach 1:
The patent applies segmentation by dividing the timing configuration into separate downlink and uplink components. Each direction can have its own sTTI length and timing relationships defined independently, allowing the system to optimize communication efficiency for each direction while managing complexity through modular timing definitions
Solution Approach 2:
The patent implements local quality by allowing different TTI parameters to be applied to different directions (downlink vs. uplink). The system can configure DL sTTI with one length and UL sTTI with another length, enabling localized optimization of communication efficiency for each direction while maintaining overall system coherence
Data Source
AI summary
A base station is disclosed, which is capable of appropriately configuring the timings of data assignment, data transmission and reception, and feedback for a case where the DL and UL sTTI lengths are different from each other. In this base station (100), a transmission section (106) transmits a downlink signal using a first short transmission time interval (sTTI) shortened in length than a TTI and used for downlink; and a reception section (107) receives an uplink signal using a second sTTI shortened in length than the TTI and used for uplink. When the first sTTI is shorter in length than the second sTTI, the reception section (107) receives the uplink signal in the second sTTI positioned after a predetermined interval from the transmission timing of the downlink signal, the predetermined interval being configured based on the length of the first sTTI.