Balanced eCCE Mapping in LTE Control Channel Transmission
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Solution Overview
Problem
In LTE systems, the imbalanced size of enhanced control channel elements (eCCEs) due to varying valid resource elements after overhead deductions leads to performance imbalance and increased implementation complexity for schedulers during ePDCCH transmission.
Innovation Solution
A method for controlling channel transmission that involves determining physical resource block pairs, grouping resource elements, calculating valid resource elements, and mapping eCCEs onto these elements to ensure balanced sizes and performance, using techniques such as grouping into eREG groups and cyclic shifts to achieve balanced eCCE sizes and simplify scheduler implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If eCCEs are mapped onto eREGs using fixed continuous mapping, then mapping simplicity is improved, but eCCE size balance deteriorates
Solution Approach 1:
The patent changes the mapping parameter from fixed continuous indexing to selective indexing based on valid RE counts. Instead of mapping eCCE#n to eREGs [nM, nM+1, ..., nM+M-1], the system calculates valid RE counts for each eREG and selects eREGs that provide balanced eCCE sizes, thus resolving the contradiction between mapping simplicity and size balance.
Solution Approach 2:
The patent performs preliminary calculation of valid RE counts for all eREGs before mapping eCCEs. By pre-calculating which eREGs have how many valid REs (after扣除 overheads like CRS, PDCCH, etc.), the system can then select eREGs that ensure balanced eCCE sizes, avoiding the need for complex real-time adjustments during mapping.
2Adaptability or versatility
If eREGs with varying valid REs are used, then resource utilization flexibility is improved, but demodulation performance balance deteriorates
Solution Approach 1:
The patent changes the selection criterion for eREGs from fixed indexing to valid RE count-based indexing. By selecting eREGs with appropriate valid RE counts, the system ensures that each eCCE receives a balanced number of valid REs for demodulation, thus maintaining performance balance while still allowing flexible resource utilization through the ability to skip eREGs with insufficient valid REs.
3Manufacturing precision
If valid RE calculation for each eREG is performed, then eCCE size balance is improved, but scheduler complexity increases
Solution Approach 1:
The patent performs the complex calculation of valid RE counts for all eREGs in advance, before the actual eCCE mapping process. This preliminary action separates the complex calculation phase from the simple selection phase, allowing the scheduler to use pre-computed valid RE count information to make simple selection decisions, thus reducing real-time scheduling complexity while maintaining eCCE size balance.
Data Source
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AI summary
Embodiments of the present invention relate to the communications field and provide a control channel transmission method and apparatus, which can ensure a balance between actual sizes of eCCEs mapped from control channels, further ensure a performance balance when demodulating each eCCE, and reduce implementation complexity of a scheduler. The method includes: grouping REs excluding a DMRS in each physical resource block pair of L determined physical resource block pairs used to transmit a control channel into N eREGs, and calculating the number of valid REs excluding other overheads in each eREG of the N eREGs; and then mapping each of the eCCEs onto M eREGs according to the number of valid REs included in each eREG of the N eREGs of each physical resource block pair, and sending the eCCE by using the resource elements included in the eREG.