Short TTI in Special Subframes for TDD Latency Reduction
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Solution Overview
Problem
Current Time Division Duplex (TDD) systems face long packet data latency due to frame alignment and Hybrid Automated Repeat Request (HARQ) round trip time limitations, which hinder data transmission efficiency and throughput in 4G and 5G wireless communication systems.
Innovation Solution
Introducing short transmission time intervals (TTIs) within special subframes of TDD systems, allowing for flexible allocation of uplink and downlink signals during guard periods or other parts of the special subframes, thereby reducing latency and improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional TDD frame structure is used, then system compatibility and legacy support are maintained, but packet data latency and HARQ round trip time are long
Solution Approach 1:
The patent segments the special subframe into multiple short TTIs (e.g., first short TTI and second short TTI), each capable of independent data transmission. This segmentation allows data to be transmitted in smaller time units, reducing the overall packet data latency while maintaining compatibility with the existing TDD frame structure through the use of special subframes.
Solution Approach 2:
The patent introduces dynamic flexibility by allowing multiple short TTIs within a special subframe, enabling the system to adapt transmission timing dynamically. This dynamic structure allows for shorter HARQ round trip times while preserving the overall TDD frame structure, resolving the contradiction between latency reduction and structure complexity.
2Productivity
If short TTIs are introduced in special subframes, then latency and HARQ round trip time are reduced, but resource allocation complexity increases
Solution Approach 1:
By dividing the special subframe into multiple short TTIs with distinct resource allocations, the patent enables more granular resource management. Each short TTI can be independently configured for uplink or downlink transmission, improving data transmission efficiency while the segmentation itself provides a structured approach to managing resource allocation complexity.
Solution Approach 2:
The patent applies short TTIs partially within the special subframe rather than transforming the entire frame structure. This partial application allows for improved transmission efficiency in specific time intervals while leaving other parts of the frame structure unchanged, thereby limiting the increase in resource allocation complexity.
3Adaptability or versatility
If multiple uplink and downlink switches are enabled, then system adaptability and throughput are improved, but frame structure complexity increases
Solution Approach 1:
The patent enables multiple dynamic switches between uplink and downlink within the special subframe by introducing multiple short TTIs that can be independently configured. This dynamic approach allows the system to adapt to varying traffic conditions and improve versatility, while the structured organization of short TTIs provides a manageable framework that limits the increase in frame structure complexity.
Data Source
AI summary
A wireless device, network node and method for communication between wireless devices and network nodes are provided. According to one aspect, a wireless device configured to communicate with a network node in a wireless communication system is provided. The wireless device includes processing circuitry configured to form at least one of an uplink, UL, signal and a downlink, DL, signal during at least one short transmission time interval, sTTI, in a special sub-frame of a radio frame to create an sTTI-containing special subframe. The wireless device further includes a transceiver configured to communicate with the network node by one of sending the uplink signal and receiving the downlink signal during the at least one sTTI.