Dynamic Control Channel Sizing for Spectral Efficiency
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Solution Overview
Problem
Existing communication systems face challenges in optimizing the spectral efficiency of control channel transmission in the downlink, leading to inefficient use of resources and unreliable scheduling due to unpredictable interference and varying channel conditions.
Innovation Solution
The solution involves using explicit or implicit channel quality indicator (CQI) feedback from user equipment to determine the appropriate modulation and coding scheme (MCS) for control channel transmission, with a predetermined field (Cat0) indicating the size of the control channel in each MCS region, allowing for dynamic adjustment based on SINR conditions and minimizing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed control channel size is used for all users, then implementation is simple, but spectral efficiency deteriorates due to inability to adapt to varying channel conditions
Solution Approach 1:
The patent implements dynamic control channel sizing by allowing the control channel size to vary based on channel conditions, user equipment capabilities, and traffic requirements. The system dynamically selects from multiple control channel formats (different resource block allocations, modulation schemes, and coding rates) to optimize spectral efficiency while maintaining implementation feasibility through predefined format tables.
2Reliability
If control channel resources are increased to ensure reliability, then transmission reliability improves, but resource utilization deteriorates due to excessive overhead
Solution Approach 1:
The patent changes multiple parameters of the control channel simultaneously including resource block allocation, modulation order, and coding rate to adapt to channel conditions. By adjusting these parameters dynamically, the system achieves reliable transmission only when necessary while minimizing overhead in good channel conditions, thus resolving the contradiction between reliability and resource overhead.
3Productivity
If adaptive control channel sizing is implemented to optimize spectral efficiency, then resource utilization improves, but system complexity increases due to additional signaling and processing
Solution Approach 1:
The patent performs preliminary actions by pre-defining multiple control channel formats with different resource allocations, modulation schemes, and coding rates in standardized tables. The base station and user equipment both have these format definitions stored, eliminating the need for complex real-time calculations and reducing signaling overhead, thus achieving adaptive sizing without excessive system complexity.
4Reliability
If control channel transmission uses high robustness settings for all users, then coverage reliability improves, but spectral efficiency deteriorates due to conservative modulation and coding
Solution Approach 1:
The patent applies local quality by allowing different control channel formats with different robustness levels to be used for different users or different time-frequency resources based on their specific channel conditions. Users in poor channel conditions receive high-robustness formats, while users in good conditions receive high-spectral-efficiency formats, thus resolving the contradiction between coverage reliability and spectral efficiency.
Data Source
AI summary
Embodiments of the invention provide methods for optimizing the spectral efficiency of control channel transmissions carrying scheduling assignments from a serving Node B to user equipments. This is accomplished by adjusting the control channel size between successive transmission time intervals according to the number of user equipments having scheduling assignments and possibly according to the modulation and coding scheme used for the transmission of each scheduling assignments.