LTE Base Station PDCCH Resource Scheduling for CCE Overlap Prevention
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Solution Overview
Problem
In LTE systems, base stations face challenges in preventing overlap of control channel elements (CCEs) among multiple PDCCHs transmitted in the same subframe, which can lead to insufficient resources for downlink and uplink scheduling requests, especially when CCEs of the common search space overlap with those of the UE-specific search space.
Innovation Solution
A PDCCH resource-based scheduling method that determines the aggregation level of the common search space based on channel quality, selects messages for allocation by prioritizing fewer candidates, and allocates PDCCH resources efficiently to prevent overlap, ensuring sufficient resources for both downlink and uplink scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple PDCCHs are transmitted in the same subframe, then the scheduling capability is improved, but CCE overlap occurs between common search space and UE-specific search space
Solution Approach 1:
The patent applies preliminary action by determining the aggregation level of the common search space before allocating PDCCH resources. The base station calculates the required CCE resources for common search space messages based on the determined aggregation level, and then uses this information to guide subsequent PDCCH resource allocation for UE-specific search spaces, preventing CCE overlap in advance
Solution Approach 2:
The patent introduces an intermediary mechanism by using the determined aggregation level and calculated CCE requirements as a mediator between common search space allocation and UE-specific search space allocation. This intermediary information enables the base station to coordinate resource allocation across different search spaces, preventing conflicts while maintaining scheduling flexibility
2Adaptability or versatility
If PDCCH resources are allocated for multiple messages, then the coverage is improved, but the number of available CCEs is reduced
Solution Approach 1:
The patent applies parameter changes by dynamically determining the aggregation level of the common search space based on current system conditions and message requirements. By adjusting this key parameter, the base station can optimize the balance between providing coverage for multiple messages and conserving available CCE resources for other allocations
3Reliability
If aggregation level of common search space is increased, then the reliability of control channel is improved, but the number of PDCCH candidates is reduced
Solution Approach 1:
The patent applies preliminary action by determining the aggregation level before finalizing PDCCH resource allocation. This preliminary determination allows the system to establish a reliable control channel foundation while still having the opportunity to optimize the number of PDCCH candidates in subsequent allocation steps based on remaining resource availability
Data Source
AI summary
Provided are a physical downlink control channel (PDCCH)-based scheduling method and apparatus suitable for use by a base station in a long-term evolution (LTE) system. The scheduling method includes: determining an aggregation level of a common search space of a PDCCH by considering channel quality of a plurality of user equipments (UEs); identifying the number of PDCCH candidates and the number of messages, which require allocation of the common search space, based on the determined aggregation level and selecting messages by a smaller number of the number of messages and the number of PDCCH candidates; and allocating PDCCH resources and physical downlink shared channel (PDSCH) resources for the selected messages. In a situation where the PDCCH resources are shared by downlink scheduling information and uplink scheduling information of different UEs, the PDCCH resource-based scheduling method can be used by the base station to efficiently utilize the PDCCH resources.