Dual Random Access Channel Configuration for Low-Power Wireless Devices
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Solution Overview
Problem
In wireless communication systems, especially those supporting ultra-low delay machine-type communication (MTC), devices with low power requirements face challenges in achieving synchronization quickly enough to transmit critical messages like alarms without excessive latency, as continuous synchronization with the network node is power-intensive and delays ultra-low delay criteria.
Innovation Solution
Configuring two types of random access channels: a first channel with standard synchronization accuracy for normal use and a second channel with lower synchronization accuracy for low-power devices, allowing them to transmit critical messages with reduced latency without continuous synchronization, using a separate or shared frequency resource and code-spreading techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If continuous synchronization is implemented to achieve low-latency random access, then transmission delay is reduced, but power consumption increases
Solution Approach 1:
The random access channel is segmented into multiple types (first RACH for high synchronization accuracy, second RACH for low synchronization accuracy). Devices can select appropriate RACH types based on their synchronization state and power constraints, avoiding continuous synchronization while enabling low-latency access when needed.
Solution Approach 2:
The system dynamically adapts the synchronization requirements based on the RACH type selected. For second RACH (low-sync), the synchronization threshold is relaxed, allowing devices to transmit without continuous synchronization. This dynamic adjustment of synchronization strictness resolves the contradiction between low latency and low power consumption.
2Reliability
If standard synchronization accuracy is required for random access channel transmission, then transmission reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
Different synchronization accuracy requirements are applied locally to different RACH types. The first RACH maintains standard high synchronization accuracy for reliable communication, while the second RACH uses relaxed low synchronization accuracy for low-power devices. This localized quality adjustment allows reliable transmission where needed without universally increasing device complexity.
Solution Approach 2:
The synchronization accuracy parameter is changed based on the RACH type. For second RACH, the synchronization threshold parameter is relaxed, allowing devices with simpler, lower-power oscillators to transmit random access messages without requiring high-precision synchronization circuits, thus reducing device complexity while maintaining acceptable reliability.
3Use of energy by moving object
If low synchronization accuracy is allowed for random access channel, then power consumption is reduced, but transmission reliability deteriorates
Solution Approach 1:
The system segments RACH resources into multiple types with different reliability characteristics. Second RACH is designed specifically for low-power applications where relaxed synchronization is acceptable, while first RACH maintains high reliability for critical communications. This segmentation allows power consumption to be reduced for non-critical devices without compromising the reliability of time-sensitive communications.
Solution Approach 2:
The second RACH enables a form of 'disposable' low-power access where devices can transmit occasional low-priority messages (like non-critical sensor data) without maintaining continuous high-precision synchronization. This accepts lower reliability for infrequent, non-critical transmissions while preserving battery life, effectively trading reliability for energy efficiency in appropriate scenarios.
Data Source
AI summary
A method of a network node of a wireless communication system is disclosed. The method comprises configuring a first random access channel for transmission of random access messages from wireless communication devices having a first synchronization accuracy vis-à-vis the network node and a second random access channel for transmission of random access messages from wireless communication devices having a second synchronization accuracy vis-à-vis the network node, wherein the second synchronization accuracy is lower than the first synchronization accuracy. The method also comprises transmitting configuration information of at least the second random access channel configurations to one of the wireless communication devices. Corresponding method for a wireless communication device is also disclosed along with a computer program product, a network node, a wireless communication device and arrangements there for.