Low Latency Wireless Communication Using Dynamic TTI Patterns
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Solution Overview
Problem
Existing wireless communication systems face challenges in achieving low latency in device-to-device (D2D) communications, particularly due to varying transmission time intervals (TTIs) that can result in higher latency transmissions.
Innovation Solution
The system employs predefined patterns of data and reference signals to support low latency communication, allowing operation with multiple TTIs of varying lengths. A base station initiates communication by sending a downlink control message indicating a transmission pattern, which user equipment (UEs) identify and use to decode sequences of data and reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system uses a single longer TTI duration for all transmissions, then communication reliability is improved, but latency increases
Solution Approach 1:
The system dynamically adjusts TTI duration based on communication requirements. Different TTI lengths (e.g., 1ms, 0.5ms, 0.25ms) are configured for different transmission types, allowing the system to adapt between reliability-oriented longer TTIs and latency-oriented shorter TTIs depending on the specific communication scenario
Solution Approach 2:
The transmission time interval is segmented into multiple duration options. Instead of using a single uniform TTI, the system divides the time resource into different granularities (short, medium, long TTIs) that can be selectively applied to different data transmissions based on their latency and reliability requirements
2Loss of time
If the system uses multiple TTIs of varying lengths, then latency is reduced, but system complexity increases
Solution Approach 1:
The system changes the TTI duration parameter based on communication needs. By configuring different TTI lengths (e.g., 1ms for normal operation, 0.5ms or 0.25ms for low latency requirements), the system can adjust the time parameter to achieve lower latency while maintaining manageable complexity through standardized configuration options
3Loss of time
If short-duration TTIs are used for UE transmissions, then latency is reduced, but compatibility with longer TTI control messages becomes challenging
Solution Approach 1:
The system design allows control messages and data transmissions to operate with different TTI durations simultaneously. The base station uses longer TTIs for control channel transmissions while UEs can use shorter TTIs for data transmissions, creating a universal system that accommodates multiple TTI lengths and ensures compatibility between control plane and user plane operations
Data Source
AI summary
Methods, systems, and devices for wireless communication using various patterns of data and reference signals are described. For example, in a system that supports operation using different duration transmission time intervals (TTIs), a base station may initiate communication with a user equipment (UE) or between two UEs, and UEs may communicate with the base station or with one another using an indicated pattern of data and reference signals. The base station may send a downlink control message indicating a transmission pattern selected from a set of patterns. UEs may identify the pattern based on the indicator and decode a sequence of data and reference signals based on the pattern. In some examples, the sequence may include a set of TTIs, which may have a shorter duration than other TTIs.