Base Station PDCCH Control Element Allocation for LTE Capacity
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Solution Overview
Problem
The Long Term Evolution (LTE) Physical Downlink Control Channel (PDCCH) resources are limited, especially in scenarios with many users, leading to bottlenecks in cell capacity, particularly in Voice over Internet Protocol (VoIP) scenarios, due to search space limitations and varying link quality requirements.
Innovation Solution
A method and arrangement in a base station that allocates control elements to user equipment based on priority values, sorting devices by link quality and reallocating resources to maximize efficient use, postponing high-resource users until better conditions and reallocating unused resources to prioritize devices with good channel quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH resources are allocated to user equipments with poor link quality, then robustness and reliability are improved, but the number of control elements required increases significantly
Solution Approach 1:
The patent changes the parameter of control element allocation by introducing a priority-based sorting mechanism. Instead of allocating control elements purely based on link quality requirements, the system sorts user equipments according to priority values and allocates control elements in that order. This allows the system to maintain reliability for high-priority users while limiting the number of control elements consumed by low-priority users with poor link quality.
2Productivity
If more control elements are allocated to accommodate users with poor link quality, then cell capacity in terms of supported users increases, but the total number of available PDCCH resources is exceeded
Solution Approach 1:
The patent introduces dynamic control element allocation based on priority values. The allocation is not static but adapts to the priority of each user equipment. By sorting users dynamically according to their priority values and allocating control elements in that order, the system can support more users (increased cell capacity) without exceeding the total available PDCCH resources, as lower-priority users receive fewer or no control elements when resources are limited.
3Loss of energy
If semi-persistent scheduling is used for VoIP, then PDCCH signaling overhead is reduced during talk-spurts, but PDCCH resources are still consumed for allocation, release, and re-transmission signaling
Solution Approach 1:
The patent applies preliminary action by establishing priority values for user equipments before scheduling decisions are made. This pre-establishment of priority allows the system to efficiently manage semi-persistent scheduling allocations, knowing in advance which users should be prioritized when PDCCH resources are available for allocation, release, or re-transmission signaling. This reduces the need for excessive PDCCH resources by ensuring that critical signaling for high-priority users is handled first.
Data Source
AI summary
Method and arrangement in base station for allocating control elements in a message comprising a predetermined number of control elements, to user equipments to be scheduled. Each user equipment is associated with a priority value, is adapted to communicate with the base station over a radio link and requires a certain number of control elements, depending on the link quality of the radio link. The method comprising sorting user equipments in a scheduling priority list and associating control elements with user equipments by selecting user equipments from the scheduling priority list and summing up the total amount of required control elements by adding the required number of control elements of each user equipment respectively, until the predetermined number of control elements in the message is reached, if two or more user equipments have been associated with the same control elements, the control elements are re-associated between the user equipments.