MAC CE Handling for Contention-Based PUSCH Latency
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, there is a need for efficient methods to manage contention-based PUSCH (Physical Uplink Shared Channel) transmissions to reduce latency and signaling overhead, as existing technologies face challenges in ensuring reliable data transmission and resource allocation without interfering with contention-free uplink transmissions.
Innovation Solution
The method involves User Equipment (UE) transmitting MAC PDUs with UE identifiers and CB grant occupancy information using configured CB grants, with eNBs informing successful UEs through Contention-based MAC CEs (Control Elements) addressed by CB-RNTIs, allowing UEs to continue data transmission on successful CB grants and trigger scheduling requests on failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If UEs transmit data using contention-based PUSCH without prior scheduling requests, then latency is reduced and throughput is improved, but signaling overhead and resource allocation complexity increase
Solution Approach 1:
The eNB pre-configures multiple CB grants with different parameters (MCS, resource blocks, power control) to UEs before contention-based transmission occurs. This preliminary configuration enables UEs to immediately transmit data without waiting for scheduling requests or grants, reducing latency while the eNB maintains control over resource allocation parameters
Solution Approach 2:
Multiple CB grants with different transmission parameters (MCS indices, resource block allocations, power control adjustments) are configured to handle varying channel conditions and traffic requirements. The eNB can select appropriate grants based on current system state, balancing latency reduction with resource allocation efficiency
2Productivity
If multiple UEs share the same CB grant resources, then resource efficiency is improved, but collision probability and transmission reliability worsen
Solution Approach 1:
CB grant resources are segmented into multiple distinct grants with different parameters (MCS, resource blocks, time/frequency slots). This segmentation allows multiple UEs to share overall CB grant resources while having dedicated parameter sets, reducing collision probability and improving transmission reliability through diversity
Solution Approach 2:
The eNB dynamically adjusts CB grant parameters and can reconfigure grants based on observed collision patterns, channel conditions, and traffic load. This dynamic adaptation optimizes the balance between resource efficiency and transmission reliability in real-time
3Adaptability or versatility
If CB grant parameters are frequently adjusted to optimize performance, then adaptability is improved, but signaling overhead increases
Solution Approach 1:
Multiple CB grants with various parameter configurations are pre-configured to UEs during initial setup or RRC connection establishment. This preliminary configuration provides a library of adaptable parameters without requiring frequent signaling updates, as UEs can select appropriate pre-configured grants based on their needs
Solution Approach 2:
Pre-configured CB grant parameter sets serve as templates that can be reused across multiple transmission opportunities. Instead of frequently signaling new parameters, the system copies and reuses validated parameter configurations, reducing signaling overhead while maintaining adaptability
Data Source
AI summary
The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for 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 MAC PDU including an identifier of the UE and CB grant occupancy information using the CB grant; receiving a CB MAC CE including the CB grant occupancy information indicated by a PDCCH addressed to the CB-RNTI in response to the MAC PDU transmission; and transmitting next uplink data using the CB grant during time duration indicated by the CB grant occupancy information if the identifier of the UE is included in the CB MAC CE.