DMRS-Based PDCCH Transmission for LTE Control Channel Capacity
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Solution Overview
Problem
Existing LTE systems face challenges in efficiently increasing control channel capacity and coverage, particularly in scenarios with low-power remote radio heads that lack their own cell ID, and do not support multi-user MIMO transmission for PDCCH, leading to limited control channel capacity and coverage issues.
Innovation Solution
The introduction of DMRS-based PDCCH (D-PDCCH) transmission in LTE Rel. 11, allowing for multi-user MIMO, rank greater than 1 transmission, and flexible configuration of antenna ports and scrambling codes, along with dynamic signaling of transmission parameters to enhance control channel capacity and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRS-based transmit diversity is used for PDCCH transmission, then coverage and robustness are improved, but control channel capacity is limited and multi-user MIMO cannot be supported
Solution Approach 1:
The patent changes the transmission parameters from CRS-based to DMRS-based transmission, enabling rank > 1 transmission and multi-user MIMO while maintaining reliable control signal reception through improved channel estimation and precoding capabilities
Solution Approach 2:
The patent introduces a new dimension to PDCCH transmission by implementing DMRS-based transmission with support for multiple antenna ports and rank > 1, transforming the single-dimension CRS-based transmission into a multi-dimensional transmission scheme that supports both coverage enhancement and capacity increase
2Adaptability or versatility
If legacy PDCCH transmission is used, then backward compatibility is maintained, but control channel capacity and coverage are insufficient for low-power remote radio heads
Solution Approach 1:
The patent creates a universal PDCCH transmission framework that can operate in both CRS-based and DMRS-based modes, allowing the system to maintain backward compatibility with legacy devices while simultaneously supporting enhanced coverage and capacity for low-power remote radio heads through DMRS-based transmission
3Productivity
If DMRS-based PDCCH transmission is introduced, then control channel capacity and multi-user MIMO are enabled, but system complexity increases
Solution Approach 1:
The patent implements dynamic configuration of DMRS-based PDCCH transmission parameters including antenna ports, scrambling codes, and resource allocation, allowing the system to adapt transmission complexity to network conditions and device capabilities, thereby enabling high capacity when needed while managing system complexity through flexible, condition-based activation
Data Source
AI summary
A wireless transmission system included at least one user equipment and a base station. The base station is operable to form a downlink control information block, modulate the downlink control information, precode the modulated downlink control information, and transmit the precoded, modulated downlink control information on at least one demodulation reference signal antenna port to the at least one user equipment. The precoded, modulated downlink control information is mapped to a set of N1 physical resource block pairs in a subframe from an orthogonal frequency division multiplexing symbol T1 to and orthogonal frequency division multiplexing symbol T2.