Self-Contained Sub-Band Search Space Design for PDCCH
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Solution Overview
Problem
In LTE networks, user equipment (UE) may not be able to access the entire downlink bandwidth due to hardware constraints and power consumption limitations, limiting its ability to monitor the Physical Downlink Control Channel (PDCCH) across the entire bandwidth.
Innovation Solution
The downlink bandwidth is divided into self-contained sub-bands, with each UE configured to monitor one or more sub-bands for its control channel, allowing CCEs to be mapped to resource element groups within the same sub-band, enabling flexible search space designs that adapt to different UE capabilities and limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE monitors PDCCH across entire downlink bandwidth, then control information coverage is complete, but hardware constraints and power consumption limitations are exceeded
Solution Approach 1:
The downlink bandwidth is divided into multiple sub-bands, and the search space for PDCCH is segmented accordingly. Each UE is configured to monitor only specific sub-bands rather than the entire bandwidth, reducing power consumption while maintaining reliable control information delivery to each UE within its assigned sub-bands.
2Adaptability or versatility
If UE monitors PDCCH across entire downlink bandwidth, then control information is fully accessible, but hardware constraints prevent full bandwidth access
Solution Approach 1:
Different sub-bands are allocated to different UEs based on their specific capabilities and requirements. Each UE receives control information in its designated sub-band with appropriate quality and configuration, rather than requiring all UEs to access the entire bandwidth. This allows the system to adapt to varying hardware constraints of different UEs.
3Area of stationary object
If search space spans entire bandwidth, then control channel coverage is maximized, but UE cannot efficiently access control channels without full bandwidth support
Solution Approach 1:
The search space is segmented into multiple sub-bands corresponding to different portions of the downlink bandwidth. Each UE is configured to search only within its assigned sub-band(s), which maintains adequate search space coverage for that UE while dramatically improving access efficiency by eliminating the need to scan the entire bandwidth.
Data Source
AI summary
Aspects of the present disclosure provide various flexible search space designs that can handle UEs with various capabilities and limitations. In some aspects of the disclosure, the downlink bandwidth may be divided into several self-contained sub-bands. Each sub-band may include one or more OFDM subcarriers or tones, and each UE may be configured to monitor one or more of the sub-bands for its downlink control channel. The sub-band is self-contained in such a way that each sub-band includes CCEs that are mapped to resource elements contained in the same sub-band. In some aspects of the disclosure, different sub-bands can be configured with the different transmission modes and pilot densities. The transmission mode, pilot density, and layer-ID may be determined as a function of each UE's search space.