Hierarchical Modulation for ULL Legacy Resource Conflicts
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Solution Overview
Problem
Wireless communication systems face resource conflicts between ultra low latency (ULL) and legacy transmissions, leading to degradation in transmission quality due to overlapping resource allocations, which existing technologies struggle to address effectively.
Innovation Solution
The implementation of a hierarchical modulation scheme and modulation symbol remapping techniques to manage overlapping resource allocations, allowing for simultaneous transmission of ULL and legacy data by using a higher order modulation scheme and adjusting soft symbol log likelihood ratio (LLR) strengths, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resource allocations are overlapped for ULL and legacy devices, then resource utilization efficiency is improved, but transmission quality degrades
Solution Approach 1:
The resource allocation is segmented into different types: overlapping resources (shared by ULL and legacy devices), ULL-only resources, and legacy-only resources. This segmentation allows the system to manage different transmission qualities for different device types while maintaining high resource utilization through overlapping allocations.
Solution Approach 2:
Different transmission qualities are applied locally to different resource types. ULL devices receive high-quality transmissions on both overlapping and ULL-only resources, while legacy devices receive transmissions on overlapping and legacy-only resources. This local quality differentiation maintains transmission quality for each device type while enabling resource overlap.
2Reliability
If hierarchical modulation is used in overlapping regions, then transmission quality for both ULL and legacy devices is maintained, but system complexity increases
Solution Approach 1:
The system dynamically selects modulation schemes based on device type and resource type. ULL devices use higher-order modulation (e.g., 64-QAM) on ULL-only resources and hierarchical modulation on overlapping resources, while legacy devices use conventional modulation (e.g., QPSK, 16-QAM). This dynamic adaptation maintains transmission quality while managing complexity through targeted application.
Solution Approach 2:
Hierarchical modulation acts as an intermediary technique that embeds both ULL and legacy transmissions within a single modulated signal. The modulated signal contains layered information that can be decoded by both ULL devices (which can decode both layers) and legacy devices (which decode only the legacy layer), thereby maintaining compatibility and quality without requiring separate transmission channels.
3Productivity
If ULL devices receive transmissions on overlapping resources, then resource efficiency is improved, but noise and bit error rates increase
Solution Approach 1:
The system changes modulation parameters specifically for ULL devices receiving transmissions on overlapping resources. ULL devices use higher-order modulation schemes (e.g., 64-QAM instead of QPSK) and adjusted coding rates to compensate for the increased noise and interference from legacy transmissions, thereby maintaining acceptable bit error rates while utilizing overlapping resources efficiently.
Data Source
AI summary
Certain aspects of the present disclosure relate to methods and apparatus for mitigating resource conflicts between ultra low latency (ULL) and legacy transmissions. A base station may determine a region of a subframe having overlapping resource allocations for a first device of a first type (e.g., ULL device) and a second device of a second type (e.g., legacy device), wherein the first device of the first type has a capability to perform certain procedures with low latency relative to the second device of the second type that lacks the capability. The base station may modulate data from the region of the subframe for transmission to the first and the second devices, using a hierarchical modulation scheme.