Discovery Signal Resource Element Allocation for Low Power Node Identification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In heterogeneous cellular networks, existing technologies face challenges such as high power consumption in cell detection, interference between low power nodes, limited cell ID availability, slow cell identification, and unnecessary uplink power control, particularly in dense deployments and when low power nodes are not actively serving users.
Innovation Solution
The introduction of a discovery signal transmitted on unused Resource Elements (REs) using a modulation scheme that allows low power nodes to uniquely identify themselves, even when sharing the same cell ID or frequency with macro nodes, and to function as a beacon for efficient inter-frequency measurements, reducing interference and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low power nodes transmit discovery signals using existing technologies, then cell detection can be performed, but power consumption increases and interference occurs between nodes
Solution Approach 1:
The discovery signal is segmented into multiple orthogonal sequences, where each sequence corresponds to a specific low power node. This segmentation allows multiple nodes to transmit simultaneously without interference, reducing the need for high power transmission while maintaining reliable cell detection capability.
Solution Approach 2:
Discovery signals are transmitted periodically at specific intervals rather than continuously. This periodic transmission reduces overall power consumption while ensuring that user equipment can detect cells at regular intervals, maintaining reliable cell detection without continuous high power usage.
2Area of stationary object
If multiple low power nodes are deployed in dense networks, then coverage area increases, but interference between nodes worsens
Solution Approach 1:
The patent introduces a new dimensional space for node identification by assigning unique orthogonal sequences from a larger codebook to each low power node. This additional dimension (code domain) allows multiple nodes to operate simultaneously in the same geographic area without interference, enabling dense network deployment while maintaining signal quality.
Solution Approach 2:
The system changes the parameter of orthogonality by using orthogonal sequences with different correlation properties. This parameter change ensures that signals from different low power nodes remain distinguishable even when transmitted simultaneously, reducing interference and enabling dense network deployment.
3Reliability
If traditional cell identification methods are used, then cell detection can be performed, but identification speed is slow
Solution Approach 1:
Orthogonal sequences are pre-assigned to each low power node and embedded in the discovery signal structure. User equipment can perform rapid correlation-based identification by matching received signals against known orthogonal sequences, enabling fast cell identification without sacrificing accuracy. This preliminary structuring of identification information allows for quick recognition.
4Productivity
If low power nodes transmit on same frequency as macro nodes, then resource utilization improves, but uplink power control becomes unnecessary and increases power consumption
Solution Approach 1:
The patent extracts the cell identification function from the uplink communication process by embedding orthogonal sequences directly in the downlink discovery signals. This separation eliminates the need for uplink power control procedures for cell identification purposes, reducing power consumption while maintaining efficient resource utilization through shared frequency spectrum.
Data Source
AI summary
In a heterogeneous network deployment that includes a macro base station and one or more low power nodes, a discovery signal is transmitted to facilitate the identification of low power nodes. The discovery signal is transmitted on a selected subset of resource elements, previously unused, to maintain backward compatibility with legacy user equipment. The transmission sequence and/or the locations of resource elements used for transmitting the discovery signal can identify the low power node to a user equipment.