Dynamic PDCCH Candidate Allocation for NR-LTE Spectrum Sharing
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Solution Overview
Problem
The challenge in New Radio (NR) technology is efficiently sharing spectrum with Long Term Evolution (LTE) without reducing the capacity for downlink control signaling and data transmission, particularly due to the increased blind decoding effort and reliability issues in secondary cell scheduling.
Innovation Solution
A wireless transmit receive unit (WTRU) is configured to dynamically determine and allocate physical downlink control channel (PDCCH) candidates for both primary and secondary cells based on subcarrier spacing, with a per-cell ratio, to optimize search space monitoring occasions and prioritize channel resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spectrum is shared with LTE by semi-statically reserving physical resources for LTE control region, then LTE control signaling is supported, but NR PCell capacity for downlink control signaling and data transmission is reduced
Solution Approach 1:
The patent implements dynamic PDCCH candidate allocation where the WTRU determines the maximum number of PDCCH candidates based on a per-cell ratio that can be adjusted according to network conditions. This dynamic approach allows the system to adaptively allocate resources between NR and LTE, avoiding the fixed resource reservation that limits NR capacity while still ensuring LTE control signaling support.
Solution Approach 2:
The patent changes the parameter of PDCCH candidate allocation from a static configuration to a dynamic one based on subcarrier spacing and per-cell ratio. By adjusting these parameters according to actual network conditions, the system can optimize the balance between LTE control signaling requirements and NR data transmission capacity, resolving the contradiction between spectrum sharing adaptability and NR productivity.
2Adaptability or versatility
If control channels are supported on SCell for scheduling data on PCell, then scheduling flexibility is improved, but downlink control information reliability deteriorates due to increased blind decoding effort
Solution Approach 1:
The patent applies partial action by allocating PDCCH candidates to SCell based on a per-cell ratio that is less than the total available candidates. This partial allocation provides sufficient scheduling flexibility for SCell while limiting the blind decoding effort to acceptable levels, thereby maintaining downlink control information reliability. The WTRU determines the maximum number of candidates to allocate to each cell's search space monitoring occasion, ensuring neither cell overwhelms the decoder.
Solution Approach 2:
The patent implements dynamic adjustment of PDCCH candidate allocation between PCell and SCell based on subcarrier spacing and per-cell ratio parameters. This dynamic allocation allows the system to optimize scheduling flexibility while controlling blind decoding complexity, resolving the contradiction between adaptability and reliability in multi-cell scheduling scenarios.
3Adaptability or versatility
If PDCCH candidates are allocated to both PCell and SCell search space monitoring occasions, then scheduling capability is enhanced, but device complexity increases due to overlapping monitoring occasions
Solution Approach 1:
The patent implements dynamic PDCCH candidate allocation where the WTRU determines the maximum number of candidates to allocate to each cell's search space monitoring occasion based on a per-cell ratio. This dynamic approach allows the device to handle multiple monitoring occasions efficiently by adaptively adjusting the number of candidates monitored in each cell, reducing overall monitoring complexity while maintaining enhanced scheduling capability across both PCell and SCell.
Data Source
AI summary
A wireless transmit receive unit (WTRU) may be configured to monitor physical downlink control channel (PDCCH) candidates of a primary cell (PCell) and a secondary cell (SCell). The WTRU may be configured to determine a time duration for PDCCH candidate budgets for a set of symbols based on a subcarrier spacing associated with the PCell and a subcarrier spacing associated with the SCell. The WTRU may be configured to determine a maximum number of PDCCH candidates to allocate to a search space monitoring occasion of the PCell and the SCell. The maximum number of PDCCH candidates may be based on a per-cell ratio. The WTRU may be configured to allocate PDCCH candidates for the search space monitoring occasion of the PCell and the search space monitoring occasion of the SCell based on the determined maximum number of PDCCH candidates. The WTRU may be configured to decode an allocated PDCCH candidate.