Partial Subframe Scheduling in Unlicensed Band Wireless Systems
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Solution Overview
Problem
Wireless access systems supporting unlicensed bands face challenges in configuring and scheduling partial subframes, leading to inefficiencies in resource allocation and potential waste of radio resources, particularly in License Assisted Access (LAA) systems, where cross-carrier scheduling and legacy resource allocation schemes are not effectively adaptable.
Innovation Solution
The implementation of methods for configuring and scheduling partial subframes (pSFs) in unlicensed bands, including cross-carrier scheduling, self-carrier scheduling, and hybrid scheduling, along with the use of Enhanced Resource Element Groups (EREGs) and Demodulation Reference Signals (DM-RS) patterns, to manage radio resources efficiently and prevent resource waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If partial subframes are configured in unlicensed bands, then resource allocation efficiency is improved, but device complexity increases due to multiple scheduling methods (cross-carrier, self-carrier, hybrid)
Solution Approach 1:
The subframe is segmented into partial subframes with different durations (e.g., 0.5ms, 1ms) to match the actual data transmission needs in unlicensed bands. This segmentation allows flexible resource allocation while maintaining manageable complexity through standardized segment sizes.
Solution Approach 2:
The system dynamically selects between cross-carrier scheduling, self-carrier scheduling, and hybrid scheduling methods based on real-time channel conditions and traffic requirements. This dynamic adaptation optimizes resource allocation efficiency without requiring complex static configurations.
2Adaptability or versatility
If cross-carrier scheduling is applied, then resource allocation flexibility is improved, but scheduling scheme restrictions are imposed on the UE
Solution Approach 1:
The base station acts as an intermediary that handles the complex scheduling decisions and configurations. The UE simply receives scheduling information and executes the data transmission, while the base station manages the cross-carrier, self-carrier, and hybrid scheduling modes based on system conditions.
Solution Approach 2:
The system changes scheduling parameters (such as scheduling mode, subframe duration, and resource allocation) based on channel conditions and traffic patterns. This allows flexible resource allocation while keeping the UE operation simple by automatically adapting parameters rather than requiring manual configuration.
3Measurement precision
If self-carrier scheduling with EPDCCH is used, then scheduling precision is improved, but decoding complexity increases due to EREG indexing requirements
Solution Approach 1:
The EPDCCH is divided into Enhanced Resource Element Groups (EREGs) with standardized indexing patterns. This segmentation provides precise scheduling control while simplifying decoding by using regular, predictable EREG structures rather than complex arbitrary mappings.
Solution Approach 2:
The system adjusts EPDCCH configuration parameters (such as EREG aggregation levels and indexing patterns) based on channel conditions and scheduling requirements. This enables precise scheduling while managing decoding complexity through adaptive parameter selection rather than fixed complex configurations.
4Productivity
If partial subframes with empty symbols are transmitted, then data transmission efficiency is improved, but channel estimation stability deteriorates
Solution Approach 1:
The base station performs preliminary channel estimation using reference signals transmitted before the partial subframe data transmission. This preliminary action establishes stable channel characteristics, allowing efficient data transmission in the subsequent partial subframe without compromising channel estimation stability.
Solution Approach 2:
Reference signals act as intermediaries that enable accurate channel estimation even when data transmission efficiency is optimized through partial subframes. These reference signals provide the necessary channel information for stable estimation while allowing the data transmission to proceed efficiently in the reduced-time partial subframes.
Data Source
AI summary
A method for a user equipment (UE) in a wireless communication system includes monitoring a physical channel carrying downlink control information (DCI); and receiving, based on the DCI, downlink data in an unlicensed band cell (Ucell). Further, the downlink data is received in a 1st subframe of a downlink transmission burst, based on being configured to monitor the physical channel on the Ucell, the downlink data is received starting in one of a partial subframe or a normal subframe in the 1st subframe, and the partial subframe is smaller than the normal subframe.