Implicit eCCE to DMRS Port Mapping for Wireless Control Channels
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Solution Overview
Problem
The legacy control channel capacity in 3GPP LTE systems bottlenecks as more users are scheduled in the same subframe, limiting performance enhancement due to insufficient PDCCH capacity, especially with frequent MU-MIMO transmissions.
Innovation Solution
An implicit mapping system between Enhanced Control Channel (eCCEs) and reference signal ports is introduced, allowing UE to derive the correct DMRS port for ePDCCH demodulation without explicit signaling, using predefined port assignments based on eCCE indices and aggregation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple eCCHs are multiplexed in one resource block with different reference signals on different antenna ports, then control channel capacity is enhanced, but the complexity of determining the mapping between eCCEs and reference signal ports increases
Solution Approach 1:
The patent applies self-service by enabling the UE to autonomously determine the DMRS port for ePDCCH demodulation through predefined mapping rules based on eCCE indices and aggregation levels, without requiring explicit signaling from the eNodeB. The UE uses the formula: DMRS port = 7 + (eCCE index mod 4), which allows self-determination of the reference signal port based on the allocated resources.
Solution Approach 2:
The patent utilizes parameter changes by establishing a systematic relationship between eCCE indices and DMRS port numbers through modular arithmetic. The mapping rule changes the parameter space from explicit port signaling to implicit port derivation based on eCCE position, transforming the determination process from complex signaling parsing to straightforward parameter calculation.
2Measurement precision
If explicit signaling is used to indicate DMRS port for ePDCCH, then mapping accuracy is improved, but signaling overhead and processing complexity increase
Solution Approach 1:
The UE determines the DMRS port autonomously using the predefined mapping rule (DMRS port = 7 + (eCCE index mod 4)), eliminating the need for explicit port indication signaling. This self-determination mechanism maintains accurate port identification while removing the overhead and processing complexity associated with explicit signaling.
Solution Approach 2:
The patent extracts the port indication information from explicit signaling and embeds it implicitly within the eCCE allocation structure itself. The eCCE index contains sufficient information to derive the DMRS port through the mapping rule, effectively removing the need for separate port signaling elements.
3Loss of time
If legacy control channel is used in first few OFDM symbols, then transmission time is reduced, but control channel capacity becomes insufficient for multiple users
Solution Approach 1:
The patent transitions from time-domain control channel transmission (first few OFDM symbols) to frequency-domain control channel transmission (resource blocks in data region). This dimensional change allows the control channel to utilize frequency resources instead of time resources, thereby increasing capacity while maintaining the ability to serve multiple users simultaneously.
Solution Approach 2:
The patent segments the control channel into multiple eCCHs that can be multiplexed within resource blocks, allowing different users to be served simultaneously in the same time period. Each eCCH can be independently allocated to different users, enabling parallel service delivery and increasing overall system capacity.
Data Source
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Figure 3(a)~3(c)
AI summary
A method and an apparatus are provided for transmitting and receiving control information in wireless communication system. An eNB generates control information, and transmits the control information using at least one enhanced Control Channel Element (eCCE) and at least one antenna port. The at least one antenna port is determined according to at least one of a starting index of the at least one eCCE and an aggregation level of the at least one eCCE.