LTE Reference Signal Allocation for Latency Reduction

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Solution Overview

Problem

Current wireless communication systems, such as LTE and LTE-Advanced, face latency issues due to processing delays in transceivers, particularly because reference signals are embedded in minimum scheduling units, limiting data transmission efficiency and increasing latency.

Innovation Solution

The solution involves separate resource allocation for dedicated reference signals, allowing for channel state measurements and coherent detection prior to user data reception, eliminating the need for reference signals in user data transmission units, thereby reducing latency and optimizing data channel resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reference signals are embedded in minimum scheduling units for data transmission, then channel state information can be obtained, but latency increases due to processing delays and resource utilization efficiency decreases

Engineering Contradiction:
Improvechannel state information accuracyVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the scheduling unit into two independent parts: a reference signal portion and a data transmission portion. The reference signal is transmitted in one minimum scheduling unit, while data transmission occurs in subsequent units. This segmentation allows channel estimation to be performed separately without delaying data transmission, thereby reducing latency while maintaining channel state information accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by transmitting the reference signal before the data transmission. The base station receives the reference signal, performs channel estimation, and prepares for data transmission in advance. This preliminary reference signal transmission enables the base station to be ready for immediate data processing without waiting for reference signals embedded in data units, thus reducing processing latency.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If reference signals are included in every minimum scheduling unit, then channel estimation is continuous, but overhead increases and data transmission efficiency decreases

Engineering Contradiction:
Improvechannel estimation continuityVSAvoiddata transmission efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the transmission resources by dedicating separate minimum scheduling units for reference signals versus data transmission. Not every minimum scheduling unit contains both reference signals and data; instead, reference signals are transmitted in dedicated units followed by data transmission units. This segmentation eliminates redundant reference signals in data units, reducing overhead while maintaining continuous channel estimation capability through periodic reference signal transmissions.

Inventive Principle:
Principle #1Segmentation

3Reliability

If reference signals are transmitted periodically, then channel state information is updated, but processing time for symbol-level operations is delayed

Engineering Contradiction:
Improvechannel state information updateVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent applies preliminary action by having the base station receive and process the reference signal before the data transmission begins. The base station performs channel estimation and prepares symbol-level processing operations in advance based on the reference signal. This allows that when data transmission starts, the processing operations are already ready, significantly reducing the processing time duration compared to waiting for reference signals embedded in data units.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2721888B1Apparatus and method for allocating the reference symbols in order to reduce the latency of the LTE system
Publication Date: 2018.12.05 NOKIA SOLUTIONS & NETWORKS OY
  • EP2721888B1 patent drawingFigure 1~2
  • EP2721888B1 patent drawingFigure 3~4
  • EP2721888B1 patent drawingFigure 5A

AI summary

Apparatus and method for communication are provided. In the proposed solution resources for transmission of user data and dedicated reference signals for demodulating a signal are allocated separately. The minimum scheduling units in frequency and time in the resources reserved for user data transmission do not comprise any reference signals.