PDCCH Transmission via Multi-Layer DMRS Mapping
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Solution Overview
Problem
The existing Physical Downlink Control Channel (PDCCH) mechanism in LTE systems faces challenges with capacity demand, interference suppression, coverage extension, and transmission efficiency due to limitations in the number of antenna ports and resource allocation, especially in multi-user and heterogeneous network scenarios.
Innovation Solution
The method involves processing downlink control information to generate codewords, scrambling and modulating them, and mapping onto multiple DMRS antenna ports for transmission, allowing for multi-layer data mapping and efficient resource utilization, thereby supporting up to 8 antennas and improving edge coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PDCCH is multiplexed with PDSCH through Time Division Multiplexing (TDM), then control information can be transmitted in the first 1-4 OFDM symbols, but the capacity of PDCCH becomes insufficient when multiple users need to be scheduled concurrently
Solution Approach 1:
The patent transitions from single-layer CRS-based transmission to multi-layer DMRS-based transmission, adding the dimension of spatial layers. By mapping downlink control information to multiple DMRS antenna ports (up to 8 ports), the system increases PDCCH capacity without requiring additional time-frequency resources, enabling concurrent scheduling of multiple users in MU-MIMO scenarios
2Reliability
If only 1-4 CRS ports are configured to control overhead, then resource efficiency is improved, but transmission performance of PDCCH becomes insufficient for edge coverage
Solution Approach 1:
The patent introduces DMRS as an intermediary for PDCCH transmission. Instead of directly using CRS ports for control information transmission, the system uses DMRS antenna ports which are specifically designed for demodulation reference. This intermediary approach allows the system to maintain low CRS port configuration (1-4 ports) while achieving reliable edge coverage through multi-layer DMRS-based transmission with up to 8 antenna ports
Solution Approach 2:
The patent changes the fundamental parameter of reference signal type from CRS to DMRS for PDCCH transmission. By switching from cell-specific reference signals to user-specific demodulation reference signals, the system can provide dedicated reference signals for each scheduled user, improving edge coverage through beamforming and multi-layer transmission without increasing the number of CRS ports
3Object-affected harmful factors
If PDCCH and PDSCH are multiplexed through TDM, then resource allocation is simplified, but inter-cell PDCCH interference cannot be effectively suppressed
Solution Approach 1:
The patent adds spatial dimension to resource allocation by utilizing multiple DMRS antenna ports for PDCCH transmission. This spatial multiplexing allows different cells to transmit PDCCH on different spatial layers, enabling interference coordination and suppression in heterogeneous networks without requiring complex time-frequency resource allocation changes
4Productivity
If cross-carrier scheduling is performed by scheduling multiple Component Carriers over a PDCCH of one CC, then control resource utilization is improved, but control resources become further insufficient
Solution Approach 1:
The patent introduces the spatial dimension through multi-layer DMRS transmission, allowing a single PDCCH to carry multiple DCI formats for cross-carrier scheduling. By mapping control information to multiple antenna ports, the system increases the information carrying capacity of each PDCCH resource, enabling efficient scheduling of multiple component carriers without proportionally increasing control resource consumption
Data Source
AI summary
Disclosed in the invention are a method and a device for transmitting downlink control information (DCI). The method comprises: processing the downlink control information to generate downlink control information code words; scrambling and modulating the downlink control information code words in turn to generate a modulation symbol sequence; mapping the modulation symbol sequence to v data layers, wherein v is an integer which is more than or equal to 1; mapping modulation symbols on the v data layers to a demodulation reference signal (DMRS) antenna port; and mapping the modulation symbols on the DMRS antenna port to a physical antenna and sending to user equipment (UE). According to the method and the device of the invention, multi-layer data transmission can be supported, the transmission mode is more flexible, and transmission efficiency is higher.