PDCCH Transmission Symbol Allocation in LTE TDD
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Solution Overview
Problem
The existing methods for transmitting physical downlink control channel signals in LTE systems lead to inefficient utilization of system resources and reduced transmission performance, particularly when the number of available resource blocks is limited, resulting in decreased cell coverage and system performance.
Innovation Solution
A method that fixes the number of symbols for transmitting physical downlink control channel signals to 2 in subframes 1 and 6, or in MBSFN subframes, when the available resource blocks are less than or equal to 10, and dynamically adjusts the number of symbols based on available bandwidth and switch-point periods, without using a physical control format indicator channel, allowing for blind detection and increased resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PCFICH is used to indicate the number of symbols for PDCCH transmission, then the transmission flexibility is improved, but the system resource utilization efficiency deteriorates due to resource wastage
Solution Approach 1:
The patent extracts and removes the PCFICH channel from the system, eliminating the need for separate control format indication signaling. The base station directly determines the PDCCH symbol count based on pre-configured rules regarding resource blocks and subframe types, thereby removing the redundant PCFICH resources while maintaining transmission flexibility through rule-based adaptation.
2Productivity
If the number of PDCCH symbols is dynamically adjusted based on resource blocks, then the resource utilization is improved, but the cell coverage deteriorates due to reduced PDCCH resources in subframes 1 and 6
Solution Approach 1:
The patent applies different symbol count rules to different subframe types. Specifically, subframes 1 and 6 (which have special TDD characteristics) are assigned a minimum of 2 PDCCH symbols to ensure adequate coverage, while other subframes can use 1 symbol when resource blocks are sufficient. This localized differentiation maintains coverage reliability in critical subframes while optimizing overall resource utilization.
3Productivity
If 1 or 2 symbols are used for PDCCH in subframes 1 and 6, then the resource utilization is improved, but the transmission performance deteriorates affecting system performance
Solution Approach 1:
The patent changes the key parameter of PDCCH symbol count from a dynamically signaled value to a rule-determined value. By establishing that subframes 1 and 6 must use at least 2 symbols while other subframes can use 1 symbol under certain conditions, the system achieves both improved resource utilization and maintained transmission performance through optimized parameter selection based on subframe characteristics.
Data Source
Figure 1
AI summary
The present invention provides a method for transmitting a PDCCH (physical downlink control channel) signal, when the number of available resource blocks of the downlink bandwidth in a radio frame is less than or equal to k, 2 symbols are fixedly used to transmit the physical downlink control channel, wherein k is a natural number. The present invention further provides another method for transmitting a PDCCH signal. In a TDD Long Term Evolution system, when the number of available resource blocks of the downlink bandwidth in a radio frame is less than or equal to k and the uplink/downlink switching period is 10ms, the transmitting end selects 2, 3 or 4 symbols to transmit the PDCCH signal in subframe 6. With the transmission method of the PDCCH signal provided in the present invention, the utilization efficiency of the system resources and the transmission performance of PDCCH can be improved.