Grant-Free HARQ Pilot Mapping for mMTC Latency
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Solution Overview
Problem
Current communication protocols, such as the hand-shake protocol, introduce significant transmission latency and require numerous signaling signals, which are costly for mMTC devices with limited power and computing capabilities, especially in scenarios with sporadic and low-speed data transmissions.
Innovation Solution
The implementation of a Grant-Free transmission protocol using two disjoint lists of pilots for initial and retransmission modes, with specific mappings to distinguish different retransmission modes like HARQ with incremental redundancy and repetition, allowing devices to transmit data without authorization and reducing the need for extensive signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hand-shake protocol is used for data transmission, then transmission reliability is improved, but transmission latency increases and signaling overhead increases
Solution Approach 1:
The system pre-configures multiple pilot lists and mapping relationships between them before actual data transmission occurs. This preliminary setup enables the base station to quickly identify whether received data is an initial transmission or retransmission without going through a lengthy hand-shake protocol, thus reducing transmission latency while maintaining reliability
Solution Approach 2:
The pilot resources are segmented into multiple distinct lists (first pilot list for initial transmissions, second pilot list for retransmissions). This segmentation allows the base station to efficiently categorize and process different types of transmissions using different pilot lists, reducing the need for extensive signaling while maintaining accurate transmission identification
2Reliability
If a hand-shake protocol is used for data transmission, then transmission reliability is improved, but signaling overhead increases
Solution Approach 1:
The invention extracts and removes the hand-shake protocol from the transmission process by using pre-configured pilot lists and mappings. The base station can directly identify transmission types through pilot comparison without requiring the multiple signaling exchanges of a hand-shake protocol, thereby significantly reducing signaling overhead while maintaining transmission reliability
Solution Approach 2:
The system enables self-service transmission identification where the pilot sequences themselves carry the information needed to distinguish initial transmissions from retransmissions. The base station autonomously identifies transmission types by comparing received pilots against stored lists and mappings, eliminating the need for explicit signaling about transmission status
3Loss of time
If Grant-Free transmission protocol is used, then transmission latency is reduced and signaling overhead is reduced, but ability to distinguish retransmissions becomes more difficult
Solution Approach 1:
Different pilot lists are assigned different qualities or characteristics - the first pilot list is dedicated to initial transmissions while the second pilot list is dedicated to retransmissions. This local differentiation in pilot assignment provides clear local quality markers that enable easy distinction between transmission types without adding system-level complexity
Solution Approach 2:
The system uses different pilot sequences (analogous to different colors) to mark different transmission types. Initial transmissions use pilots from the first list while retransmissions use pilots from the second list. This 'color coding' of pilots provides an intuitive and simple mechanism for the base station to distinguish transmission types without complex analysis
Data Source
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AI summary
The present invention pertains to a method of telecommunication between a base station (eNB) and users (UE1, UE2) comprising: - identification of two disjoint lists of pilots, namely a first for initial uplink transmissions (1 st Tx) and a second for uplink retransmissions (ReTx), - definition of a first mapping between the pilots of the two lists.