Interference Measurement Resource Allocation for New Carrier Type

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Solution Overview

Problem

In LTE/LTE-A systems, the existing interference measurement methods face challenges in accurately measuring intra-cell interference in Distributed Antenna Systems (DAS) due to the lack of unique scrambling codes among antenna groups within the same cell, leading to inaccurate Signal-to-Interference Ratio (SIR) and performance degradation.

Innovation Solution

The proposed solution involves an interference measurement resource (IMR) allocation method and apparatus that determines whether a terminal supports New Carrier Type (NCT) subframes, allocates IMR at Resource Elements (REs) not used by other signals, and transmits these resources to the terminal for interference measurement, allowing for accurate measurement of both inter-cell and intra-cell interference by using subframes with or without Cell-specific Reference Signals (CRS).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing interference measurement methods are used in DAS, then the system can operate with distributed antennas, but the measurement precision of intra-cell interference deteriorates due to lack of unique scrambling codes

Engineering Contradiction:

Improveinterference measurement accuracyVSAvoidscrambling code allocation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the interference measurement process by introducing separate IMR resources for different antenna groups within the same cell. Each antenna group is assigned a unique scrambling code for its IMR, allowing the terminal to measure interference from each antenna group separately. This segmentation enables accurate intra-cell interference measurement while maintaining system operability in DAS configurations.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If control channels and reference signals are allocated in NCT subframes, then the system can provide coverage and control functionality, but the quantity of available resources for data transmission decreases

Engineering Contradiction:

Improveavailable radio resourcesVSAvoidcontrol signal coverage

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent extracts control channels and common reference signals from NCT subframes, leaving only essential synchronization signals and physical broadcast channel. This extraction minimizes control overhead and maximizes the quantity of radio resources available for data transmission while maintaining basic control functionality through the remaining essential signals.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes CRS subframes serve multiple functions: they provide both control signal transmission and interference measurement capabilities. By configuring IMR in CRS subframes, the same resource elements that carry control information also enable interference measurement, thereby maintaining control reliability while efficiently utilizing available resources.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If IMR is allocated in subframes with CRS, then the terminal can measure interference using available reference signals, but the measurement precision deteriorates due to signal overlap and interference from CRS

Engineering Contradiction:

Improveinterference measurement accuracyVSAvoidinterference from CRS

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by muting (zeroing out) the CRS transmission in specific resource elements where IMR is allocated. This preliminary suppression of CRS in IMR regions prevents CRS from interfering with interference measurement, allowing the terminal to accurately measure interference from other cells and antenna groups without contamination from serving cell CRS.

Inventive Principle:

Principle #10Preliminary action

4Loss of information

If NCT subframes are introduced to reduce overhead, then the loss of information from control channels decreases, but the difficulty of detecting and measuring interference increases due to reduced reference signal availability

Engineering Contradiction:

Improvecontrol channel overheadVSAvoidinterference detection difficulty

Core Design Contradiction:

Loss of informationVSDifficulty of detecting and measuring

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9520974B2Interference measurement method and apparatus for new carrier type

Publication Date: 2016.12.13 SAMSUNG ELECTRONICS CO LTD

AI summary

An Interference Measurement Resource (IMR) allocation method and apparatus for allocating resources for efficient interference measurement in a downlink in a system supporting a New Carrier Type (NCT) is provided. The interference measurement configuration method of a base station transmitting subframes including, or not including, Cell-specific Reference Signals (CRS) in a wireless communication system includes determining whether a terminal supports a New Carrier Type (NCT) subframe, allocating, when the terminal supports the NCT subframe, Interference Measurement Resources (IMR) to the terminal at Resource Elements (REs) where other signals are not mapped in the subframe, transmitting information on the allocated IMR to the terminal, and transmitting the subframe including the allocated IMR to the terminal.