Signaling E-PDCCH Presence via Phase-Shifted Reference Signals

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Solution Overview

Problem

In LTE systems, the downlink control channel (PDCCH) does not efficiently utilize advanced multi-antenna techniques, leading to suboptimal resource allocation and interference issues, especially when sharing resources with the physical downlink shared channel (PDSCH), resulting in wasted bandwidth and restricted multiplexing flexibility.

Innovation Solution

Implementing a method to signal the presence of E-PDCCH within PDSCH allocations using phase-shifted reference signals, allowing for flexible time-domain or frequency-domain multiplexing, enabling the UE to determine if a resource block is used for control channel transmission and adjust accordingly, thereby optimizing resource utilization without additional signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If E-PDCCH and PDSCH share the same resource blocks, then resource utilization efficiency is improved, but interference between control channel and data channel increases

Engineering Contradiction:

Improveresource utilization efficiencyVSAvoidinterference between control channel and data channel

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The resource block is segmented into different regions: some resource elements are allocated to E-PDCCH while others are allocated to PDSCH. This segmentation allows both control channel and data channel to coexist in the same resource block without complete overlap, reducing interference while maintaining high resource utilization efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the resource block are assigned different functions: control channel elements in specific resource elements and data elements in other resource elements. This local differentiation of quality and function within the same resource block enables simultaneous transmission of control and data with minimized mutual interference.

Inventive Principle:

Principle #3Local quality

2Reliability

If PDCCH uses traditional frequency selective scheduling, then resource allocation performance is improved, but signaling overhead increases

Engineering Contradiction:

Improveresource allocation performanceVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent merges PDCCH and PDSCH into the same resource block, combining control channel and data channel transmissions. This merging eliminates the need for separate resource allocation signaling for PDCCH, as the resource allocation is implicitly indicated through the PDSCH resource allocation information, thereby reducing signaling overhead while maintaining frequency selective scheduling performance.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If E-PDCCH resources are reserved separately from PDSCH, then control channel reliability is improved, but multiplexing flexibility is reduced

Engineering Contradiction:

Improvecontrol channel reliabilityVSAvoidmultiplexing flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The resource block is designed to serve multiple functions simultaneously: it can transmit both E-PDCCH control information and PDSCH data, and the same resource block can be dynamically allocated to different UEs with different resource allocation patterns. This multi-functionality provides both control channel reliability through dedicated resource elements and multiplexing flexibility through dynamic resource allocation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The resource allocation between E-PDCCH and PDSCH within the resource block is dynamic rather than fixed. The network can flexibly adjust the proportion and distribution of resources allocated to control channel versus data channel based on traffic conditions, UE requirements, and channel state, thereby maintaining both reliability and flexibility.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the multiplexing flexibility of E-PDCCH and PDSCH, reducing waste and ensuring efficient use of radio resources, allowing for full multiplexing without penalizing either channel, thus improving overall network performance.

Implementation Method 1

signal an indication whether a portion of (TDM) or a full (FDM) resource block comprising the allocated downlink shared channel is used for a control channel transmission

Methodology Applied

Scientific EffectPhase shifting: Phase Modulation

Data Source

PatentUS8917679B2Method for signaling the overlap of downlink control and data channels

Publication Date: 2014.12.23 NOKIA TECHNOLOGIES OY

AI summary

A network signals an allocation (PDCCH) for a downlink shared channel (PDSCH); and also signals an indication (reference signal RS) whether a resource block (PRB) comprising the allocated downlink shared channel is used for a control channel transmission (E-PDCCH). Examples include the E-PDCCH being time or frequency multiplexed with the PDSCH; and the indication being a different RS sequence (at least one element being phase shifted) than an original RS sequence used if the PRB were not used for the E-PDCCH. The UE tests for the phase shift by blind decoding. If the phase shift is present the UE a) decodes a portion of the PRB for data if the network is using TDM for its E-PDCCH/PDSCH multiplexing, orb) decodes the full PRB only for the E-PDCCH if the network is using FDM for its E-PDCCH/PDSCH multiplexing.