DMRS Pattern Design for sTTI Wireless Systems
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Solution Overview
Problem
In wireless communication systems, the existing designs for short transmission time intervals (TTIs) face challenges in avoiding collisions between demodulation reference signals (DMRS) and legacy cell-specific reference signals (CRS) and channel state information reference signals (CSI-RS), which hinders efficient data transmission and increases latency.
Innovation Solution
A new pattern for the downlink demodulation reference signal is defined to prevent collisions with legacy CRS and CSI-RS, allowing for the demodulation of short physical downlink control channels (sPDCCH) and short physical downlink shared channels (sPDSCH) in a short TTI structure, ensuring reliable data transmission without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new DMRS pattern is defined for sTTI, then signal collision with legacy CRS and CSI-RS is avoided, but system complexity increases due to multiple reference signal patterns
Solution Approach 1:
The reference signal pattern is segmented by time domain position, with different patterns applied to different OFDM symbol positions within the sTTI. This allows the system to avoid collisions with legacy CRS and CSI-RS by assigning specific patterns to specific time resources, thereby maintaining reliability while managing complexity through structured organization.
Solution Approach 2:
Different DMRS patterns are applied locally to different time-frequency resources within the sTTI structure. The pattern selection is localized to specific OFDM symbols and resource blocks, allowing optimal performance in each local region while avoiding collisions with legacy signals in their respective regions.
2Loss of time
If short TTI structure is implemented, then latency is reduced, but signal collision with legacy reference signals increases
Solution Approach 1:
The solution moves the problem from a one-dimensional time resource conflict to a two-dimensional time-frequency resource allocation by introducing specific frequency domain patterns for DMRS. This allows sTTI to achieve low latency while avoiding collisions by utilizing the additional frequency dimension for pattern differentiation.
Solution Approach 2:
The DMRS pattern is predetermined and pre-configured for specific sTTI structures before transmission occurs. This preliminary definition of patterns ensures that collision avoidance is built into the system architecture from the start, eliminating the need for dynamic collision detection and resolution during transmission.
Data Source
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AI summary
In a method for supporting a short transmission time interval (sTTI) in a wireless communication system according to one embodiment of the present invention, the method is performed by a terminal, and comprises the steps of: receiving a reference signal for decoding a downlink channel; and decoding the downlink channel by using the reference signal for decoding the downlink channel, wherein the reference signal for decoding the downlink channel may be transmitted by using a pattern to which a frequency separation is applied, in the case of collision with a cell-specific reference signal.