MAC-CE Decoding Configuration for Wireless Communication Latency
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Solution Overview
Problem
The complexity of decoding medium access control (MAC) control elements (CEs) in wireless communications systems leads to inefficiencies and poor coordination between devices, particularly due to the need for sequential decoding of code block groups (CBGs) and multiple hybrid automatic repeat request (HARQ) retransmissions, which increases decoding complexity and latency.
Innovation Solution
A streamlined decoding configuration is established where a fixed set of CBGs contains all MAC-CEs, allowing for early identification and decoding of MAC-CEs, reducing the need for sequential decoding and enabling early application of MAC-CE instructions, thereby improving communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential decoding of code block groups (CBGs) is performed to ensure reliable reception of MAC-CEs, then reliability of MAC-CE decoding is improved, but decoding complexity and latency increase
Solution Approach 1:
The MAC PDU is segmented into multiple code block groups (CBGs), where the first CBG is dedicated to carrying MAC-CEs and subsequent CBGs carry MAC SDUs. This segmentation allows the receiver to decode and process MAC-CEs from the first CBG independently, without waiting for sequential decoding of all CBGs, thereby reducing decoding complexity and latency while maintaining reliability.
2Reliability
If multiple HARQ retransmissions are performed to ensure successful delivery of MAC-CEs, then reliability of control signaling is improved, but transmission latency increases
Solution Approach 1:
MAC-CEs are placed in the first CBG which is transmitted preliminarily in the initial HARQ transmission. The receiver can decode and act on MAC-CEs from this first CBG without waiting for potential retransmissions of subsequent CBGs containing MAC SDUs. This preliminary placement of critical control elements reduces the need for multiple HARQ retransmissions and associated latency.
3Device complexity
If all MAC-CEs are placed in a single CBG to simplify structure, then device complexity is reduced, but reliability decreases due to vulnerability to single-point failure
Solution Approach 1:
The patent merges the first CBG (carrying MAC-CEs) with subsequent CBGs (carrying MAC SDUs) into a single MAC PDU transmission. This combining approach maintains structural simplicity while ensuring that MAC-CEs in the first CBG can be decoded independently, providing reliability without requiring separate transmission structures.
Data Source
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Figure 3A~3B
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) and a base station may communicate medium access control (MAC) protocol data units (PDUs). The UE and base station may use a set of decoding conditions, or a decoding configuration, to identify a set of code block groups (CBGs) within a packet that include MAC-control elements (CEs). For example, the decoding configuration may indicate a fixed set of CBGs which contain the MAC-CEs within a MAC PDU. In another example, the configuration may specify a limit on the number and/or size of the MAC-CEs within each MAC PDU packet. In any case, the decoding configuration may provide rules known by both transmitting and receiving devices for identifying and decoding CBGs that include MAC-CEs such that MAC-CE information may be applied by the receiving wireless device.