MAC PDU Multiplexing for Wireless RAR Collision Reduction
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Solution Overview
Problem
Wireless networks face collisions due to overlapping transmission areas when user equipment (UE) extends the random access response (RAR) window, leading to inefficiencies and potential data losses.
Innovation Solution
The proposed solution involves multiplexing media access control (MAC) random access responses from different cells into a single MAC protocol data unit (PDU), with indications in the MAC sub-header or backoff indicator sub-header to distinguish between licensed and unlicensed cells, thereby avoiding collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the random access response window is extended to improve coverage and reliability, then more UEs can be served, but collisions increase due to overlapping transmission areas from different cells
Solution Approach 1:
The patent segments the random access response by including cell identification information (such as virtual cell ID or physical cell ID) in the RAR message. This allows the UE to identify which cell transmitted the RAR, enabling segmentation of the transmission area and reducing collisions by allowing UEs to distinguish between RARs from different cells.
Solution Approach 2:
The patent introduces an intermediary element - the cell identification field - that mediates between multiple transmitting cells and the receiving UE. This intermediary information allows the UE to correctly associate RARs with their respective transmitting cells, preventing collision confusion while maintaining extended coverage benefits.
2Productivity
If multiple preambles are received in the same random access channel resource from different cells, then network capacity increases, but collision detection becomes difficult without additional identification information
Solution Approach 1:
The patent applies segmentation by dividing the random access response space into cell-specific segments through the inclusion of cell ID information. This allows the network to handle multiple preambles from different cells in the same RACH resource while enabling the UE to detect and distinguish between responses from different cells, thus maintaining high network capacity while simplifying collision detection.
3Productivity
If random access responses from different cells are multiplexed into a single MAC PDU, then transmission efficiency improves, but the complexity of managing different single frequency networks increases
Solution Approach 1:
The patent segments the MAC PDU structure by including cell identification information in each random access response within the multiplexed PDU. This allows efficient multiplexing of responses from different cells while providing the UE with the information needed to distinguish between different single frequency networks, thereby maintaining transmission efficiency without excessively increasing management complexity.
Solution Approach 2:
The patent creates a universal MAC PDU structure that can carry random access responses from multiple different cells and single frequency networks simultaneously. The included cell identification field provides multi-functionality by enabling the same PDU structure to handle responses from various sources without requiring separate processing paths, thus improving transmission efficiency while keeping complexity manageable.
Data Source
AI summary
Methods, apparatus, and systems for improving data transmission efficiency in a wireless network are described. In one example aspect, a wireless communication method includes receiving a plurality of preambles and a plurality of corresponding media access control random access responses through a plurality of cells, upon a determination that the plurality of preambles is received in the same random access channel resource, multiplexing the plurality of corresponding media access control random access responses into one medium access control protocol data unit, upon a determination that the plurality of corresponding media access control random access responses is in different single frequency networks, adding an indication, to a media access control sub-header, that the one medium access control protocol data unit includes the plurality of media access control random access responses, and transmitting the medium access control protocol data unit including the media access control sub-header with the indication.