Frequency Hopping Design for Grant-Free URLLC Transmission
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Solution Overview
Problem
In mobile communications, especially for New Radio (NR) ultra-reliable and low latency communications (URLLC), uplink grant-free transmissions face challenges with collisions due to limited resources, necessitating effective frequency hopping designs to exploit frequency diversity and reduce latency and increase reliability.
Innovation Solution
The proposed solution involves configuring user equipment (UE) with specific frequency hopping patterns, including random, orthogonal/quasi-orthogonal, and common basic patterns, which incorporate UE-specific information to randomize collisions and optimize resource allocation, allowing for efficient uplink grant-free transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple UEs share the same grant-free resources, then resource utilization efficiency is improved, but collision probability increases
Solution Approach 1:
The patent segments the frequency resources by dividing the available bandwidth into multiple sub-bands. UEs are assigned to different sub-bands for frequency hopping, which segments the collision-prone resource pool into smaller, less conflicting segments. This allows more UEs to share resources simultaneously while reducing collision probability through spatial-frequency separation.
Solution Approach 2:
The patent introduces frequency dimension diversity by implementing frequency hopping across multiple sub-bands. Instead of relying solely on time-domain multiplexing, the system adds a frequency dimension where UEs can hop between different sub-bands, effectively transforming a one-dimensional resource conflict into a multi-dimensional resource allocation problem that reduces collisions.
2Reliability
If frequency hopping is implemented to reduce collisions, then transmission reliability is improved, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring frequency hopping patterns and sub-band assignments for UEs before transmission occurs. The network node pre-determines which sub-bands are available and configures UE-specific hopping patterns, so that when transmissions occur, the frequency hopping execution is straightforward and does not require complex real-time decision-making, thus reducing system complexity while maintaining reliability benefits.
Solution Approach 2:
The patent changes the frequency parameter dynamically through frequency hopping, where UEs transmit on different frequency sub-bands across different time instances. This parameter change exploits frequency diversity to improve reliability by avoiding persistent collisions on the same frequency, while the hopping pattern is designed to be manageable in terms of complexity through preconfiguration.
3Speed
If grant-free transmission is used to reduce latency, then transmission speed is improved, but collision impact increases
Solution Approach 1:
The patent implements periodic frequency hopping where UEs systematically hop between sub-bands at predetermined intervals. This periodic action in the frequency domain complements the latency-reducing grant-free transmission by ensuring that even if collisions occur initially, subsequent periodic hops will likely place transmitting UEs on different frequencies, thereby reducing collision impact while maintaining the low-latency benefit of grant-free access.
Data Source
AI summary
Various solutions for frequency hopping design for grant-free transmission with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a frequency hopping pattern from a network node. The apparatus may determine a frequency hopping location according to the frequency hopping pattern. The apparatus may perform an uplink grant-free transmission according to the frequency hopping position. The frequency hopping pattern may comprise user equipment specific information.