Contention-Based PUSCH MAC CE Handling for Collision Avoidance
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, there is a challenge in efficiently managing contention-based PUSCH (Physical Uplink Shared Channel) transmissions, where UEs need to identify available resources without pre-scheduling, to reduce latency and signaling overhead, while maintaining system stability and throughput.
Innovation Solution
The method involves using Contention-Based (CB) grants that include a UE identifier, allowing multiple UEs to transmit on the same CB grant, with the eNodeB identifying the UE through buffer status information and UE identifier, and providing dedicated uplink grants to prevent collisions and optimize resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-scheduling is used for PUSCH transmission, then resource allocation is controlled and collisions are avoided, but latency increases and signaling overhead increases
Solution Approach 1:
The system performs preliminary configuration of CB grants with UE identifiers in advance, allowing UEs to directly transmit on pre-configured resources without real-time scheduling requests. This preliminary setup enables collision-free transmission while eliminating the latency associated with dynamic scheduling procedures.
Solution Approach 2:
UEs autonomously select and transmit on CB grant resources based on their own identifiers and buffer status information, without requiring network coordination for each transmission. This self-service mechanism eliminates signaling overhead and reduces latency while maintaining collision avoidance through the UE identifier-based resource selection.
2Reliability
If pre-scheduling is used for PUSCH transmission, then resource allocation is controlled, but signaling overhead increases
Solution Approach 1:
The patent extracts the essential resource allocation control function by embedding UE identifiers directly in the CB grant configuration, separating this critical control information from the regular scheduling signaling. This extraction maintains resource allocation control while eliminating the need for continuous scheduling requests and grants, thereby reducing signaling overhead.
Solution Approach 2:
The system uses UE identifiers as copies or proxies for complex scheduling information. Instead of transmitting detailed scheduling commands for each transmission, the network uses the UE identifier to implicitly determine resource allocation, significantly reducing signaling overhead while maintaining control.
3Productivity
If multiple UEs transmit on the same CB grant, then resource utilization is improved and latency is reduced, but collision probability increases
Solution Approach 1:
The patent applies local quality by making each CB grant resource unique through the inclusion of UE-specific identifiers. This differentiation ensures that even though multiple UEs can transmit on CB grants simultaneously, each UE's transmission is locally distinguished by its identifier, preventing collisions while maintaining high resource utilization.
Solution Approach 2:
The system segments the CB grant resources by UE identifier, creating virtually separate transmission channels for each UE within the same CB grant framework. This segmentation allows multiple UEs to share CB grant resources without collisions, as each UE's transmission is uniquely identified and separated in the resource space.
Data Source
Figure 1~2A
Figure 2B
Figure 3(a)~4
AI summary
The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for d receiving a MAC CE for contention-based PUSCH in a wireless communication system, the method comprising: configuring a CB grant and a CB-RNTI associated with the CB grant; transmitting a first MAC PDU including an identifier of the UE on the CB grant; receiving a CB MAC CE indicated by a PDCCH addressed to the CB-RNTI in response to the MAC PDU transmission; determining that the first MAC PDU transmission is failed if the identifier of the UE isn't included in the MAC CE; and transmitting a second MAC PDU including the identifier of the UE on the CB grant.