MTC Device Narrowband SPS HARQ Timing
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Solution Overview
Problem
Current LTE systems are costly for Machine Type Communication (MTC) due to their high bandwidth requirements, and existing solutions do not efficiently support Semi-Persistent Scheduling (SPS) and Hybrid Automatic Repeat Request (HARQ) procedures over reduced bandwidth.
Innovation Solution
A method for MTC devices to repeatedly transmit and receive channels based on SPS and perform HARQ processes using an asynchronous method, where the number of repetitions is indicated by the base station through Downlink Control Information (DCI), allowing for efficient operation even without continuous radio resource assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTE system bandwidth is used for MTC, then communication reliability is improved, but communication cost increases
Solution Approach 1:
The patent segments the system bandwidth into multiple narrowbands, allowing MTC devices to operate in reduced bandwidth (e.g., 1.08 MHz) while the overall system maintains full bandwidth capability. This segmentation enables cost-effective MTC devices to achieve reliable communication without requiring access to the entire LTE system bandwidth.
2Productivity
If Semi-Persistent Scheduling is applied to MTC over reduced bandwidth, then communication efficiency is improved, but procedure complexity increases
Solution Approach 1:
The patent applies Semi-Persistent Scheduling where resources are allocated in advance for repeated transmissions. The base station configures SPS parameters including number of repetitions, resource blocks, and timing ahead of time, allowing MTC devices to perform repeated channel transmissions without continuous scheduling decisions, thereby simplifying real-time processing while maintaining efficiency.
Solution Approach 2:
The patent introduces dynamic HARQ-ACK timing indication through DCI format 6-0A/6-0B, allowing the base station to flexibly adjust the timing of HARQ acknowledgments based on channel conditions and traffic requirements. This dynamic adjustment optimizes communication efficiency while managing procedure complexity through adaptive rather than rigid scheduling.
3Reliability
If repeated channel transmission is performed, then communication reliability is improved, but transmission time increases
Solution Approach 1:
The patent implements periodic repeated transmissions of physical channels (PUSCH, PDSCH, PUCCH) over multiple subframes with configured periodicity. By transmitting the same channel repeatedly at regular intervals, the MTC device ensures reliable delivery while the base station can stop repetitions early upon successful reception, optimizing the balance between reliability and transmission time.
Solution Approach 2:
The patent employs HARQ (Hybrid Automatic Repeat Request) feedback mechanisms where the base station sends ACK/NACK signals to confirm successful reception or request retransmission. This feedback-driven approach allows the system to achieve high reliability through targeted retransmissions rather than blind repeated transmissions, reducing overall transmission time while maintaining reliability.
Data Source
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AI summary
One disclosure of the present specification provides a method for a machine type communication (MTC) device to perform communication using a narrow band. The method may comprise the steps of: monitoring a downlink control channel indicating the release of semi-persistent scheduling in the process of repeatedly transmitting uplink data channels on the basis of the semi-persistent scheduling; and if the downlink control channel indicating the release of the semi-persistent scheduling is detected, determining a timing of stopping the repeated transmission of the uplink data channels, and stopping the repeated transmission of the uplink data channels according to the determined timing.