Wireless Data Transmission Using Sub-TTIs for Sub-Millisecond Latency
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Solution Overview
Problem
Existing wireless communication systems face challenges in reducing end-to-end latency beyond 1 ms due to the fixed 1 ms transmission time interval (TTI) in LTE standards, which limits the processing and decoding of data, especially in ultra-low delay services requiring constant bit rates.
Innovation Solution
Implementing a modified subframe format with reduced TTIs of 1 OFDM symbol length and a constant payload data throughput, along with early processing of symbols, and using carrier aggregation to achieve backward compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a fixed 1 ms transmission time interval (TTI) is used in LTE standards, then system stability and backward compatibility are maintained, but end-to-end latency cannot be reduced below 1 ms
Solution Approach 1:
The patent segments the fixed 1 ms TTI into multiple smaller processing units called sub-TTIs or mini-slots, each containing a subset of OFDM symbols. This allows the system to process and transmit data in smaller time granularities (e.g., 0.5 ms, 0.25 ms, or even shorter), thereby reducing end-to-end latency while maintaining compatibility with the overall 1 ms frame structure through carrier aggregation.
2Loss of time
If the TTI is reduced to enable faster processing, then end-to-end latency decreases, but constant bit rate maintenance becomes more difficult
Solution Approach 1:
The patent introduces dynamic resource allocation where the number of OFDM symbols allocated to data transmission versus control information can be flexibly adjusted within each sub-TTI. This dynamic structure allows the system to adapt the payload size and transmission resources to maintain constant bit rate requirements while using shorter processing intervals, resolving the contradiction between reduced latency and rate stability.
3Loss of time
If early processing of symbols is implemented, then latency is reduced, but system complexity increases due to modified subframe formats
Solution Approach 1:
The patent divides the traditional subframe into multiple smaller units (sub-TTIs or mini-slots) that can be independently processed. This segmentation enables early processing of received symbols without requiring the complete 1 ms subframe to be received and processed, thereby reducing latency. The modified subframe format uses standardized OFDM symbol structures that maintain reasonable implementation complexity.
4Productivity
If modified subframe formats with reduced TTIs are used, then throughput and processing speed increase, but backward compatibility with existing LTE standards is lost
Solution Approach 1:
The patent designs the modified subframe format to be multi-functional: it can operate in reduced TTI mode for high-throughput applications while maintaining the ability to aggregate multiple component carriers. The structure is designed to be compatible with existing LTE physical layer procedures and signal formats, allowing gradual deployment and coexistence with legacy systems through carrier aggregation, thus preserving backward compatibility while enabling enhanced productivity.
Data Source
AI summary
A receiver is configured is configured to receive a data signal, the data signal having at least one data signal block, the data signal block having a predefined duration in the time domain, a number of symbols in the time domain and a bandwidth in the frequency domain, wherein the data signal block is received over a plurality of transmission intervals, wherein a length of one transmission interval is shorter than the duration of the data signal block so that a subset of the symbols of the data signal block is received over one transmission interval, and wherein the receiver includes a signal processing device configured to process the symbols of the data signal block which have been received over one transmission interval.