DMRS-Based PDCCH Enhancements for Multi-User MIMO
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Solution Overview
Problem
Existing LTE systems face challenges in maximizing control channel capacity and coverage, particularly in scenarios involving coordinated multi-point transmission where low-power remote radio heads lack cell IDs, and there is a need for improved PDCCH transmission methods to support multi-user and multiple input, multiple output operations.
Innovation Solution
The introduction of DMRS-based PDCCH (D-PDCCH) transmission in LTE Rel. 11, allowing for multi-user MIMO and supporting rank greater than 1 transmission, with semi-static or dynamic configuration of antenna ports and scrambling codes, and flexible control region design 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 spatial and frequency diversity are exploited to maximize robustness and reliable reception, but the control channel capacity and coverage are limited in coordinated multi-point scenarios
Solution Approach 1:
The patent changes the fundamental transmission parameters from CRS-based to DMRS-based transmission, enabling support for multiple antenna ports (up to 8) and multiple ranks (up to 4), thereby increasing control channel capacity while maintaining reliability through diverse transmission schemes
Solution Approach 2:
The patent introduces dynamic configuration of antenna ports and scrambling codes, allowing the system to adapt control channel transmission to varying channel conditions and traffic requirements, thereby enhancing both capacity and reliability in different operational scenarios
2Reliability
If legacy PDCCH transmission with CRS-based diversity is used, then robustness is maximized through transmit diversity and cross-interleaving, but multi-user MIMO and rank greater than 1 operations cannot be supported
Solution Approach 1:
The patent introduces DMRS-based transmission with support for multiple antenna ports and ranks, fundamentally changing the transmission parameters to enable multi-user MIMO operations while maintaining robustness through diverse transmission schemes and configurable diversity methods
Solution Approach 2:
The patent segments the control channel transmission into multiple independent DMRS-based streams that can be independently configured for different users and ranks, enabling multi-user MIMO operations while each stream maintains its own robustness through individual transmission diversity
3Reliability
If R-PDCCH with semi-static resource configuration is used for relay backhaul, then dedicated resources are reserved for eNB-to-RN link, but control channel flexibility and adaptability to dynamic conditions are reduced
Solution Approach 1:
The patent introduces dynamic configuration of antenna ports, scrambling codes, and transmission parameters for R-PDCCH, allowing the semi-statically reserved resources to be dynamically optimized for varying channel conditions and traffic requirements, thereby enhancing both reliability and flexibility
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.