Dormant Small Cell Discovery via Periodic Signal Transmission
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Solution Overview
Problem
In heterogeneous wireless networks, dormant small cells do not transmit downlink broadcast or control channels, making it difficult for IDLE mode UEs to access them, which hinders efficient small cell on/off transitions and interferes with neighboring cells.
Innovation Solution
A method where dormant small cells transmit discovery signals, such as PSS, SSS, and CRS, using a periodic transmission pattern with active and non-active portions, allowing UEs to configure a duty cycle for signal measurement, enabling them to detect and access dormant small cells efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If dormant small cells do not transmit downlink broadcast or control channels, then interference with neighboring cells is reduced and energy consumption is lowered, but user equipment cannot discover or access these dormant cells
Solution Approach 1:
The patent extracts only the essential discovery signals (PSS, SSS, CRS) from the full set of downlink channels, allowing dormant cells to transmit minimal signals for UE discovery while avoiding transmission of broadcast and control channels that would cause interference and consume energy
Solution Approach 2:
The patent implements periodic transmission of discovery signals at configured intervals, allowing dormant cells to periodically announce their presence to UEs without continuous transmission, thereby reducing interference while maintaining discoverability
2Difficulty of detecting and measuring
If dormant small cells transmit discovery signals continuously, then user equipment can easily discover them, but energy consumption increases and interference with neighboring cells worsens
Solution Approach 1:
The patent implements periodic transmission of discovery signals at configured intervals, allowing dormant cells to periodically announce their presence to UEs without continuous transmission, thereby reducing interference while maintaining discoverability
Solution Approach 2:
The patent changes the transmission parameters of discovery signals by configuring duty cycles and periodicities, allowing the system to optimize between discovery performance and energy consumption based on network conditions
3Productivity
If small cells switch between active and dormant states, then network capacity and energy efficiency are improved, but the transition process becomes more complex and requires coordination
Solution Approach 1:
The patent performs preliminary configuration of discovery signal parameters and duty cycles before small cell state transitions, allowing UEs to be pre-informed of transmission patterns, which simplifies the actual transition process and reduces coordination complexity
Solution Approach 2:
The patent uses discovery signals as an intermediary mechanism that facilitates state transitions by providing a standardized interface for UEs to detect and respond to dormant cell states, simplifying the overall transition coordination
Data Source
AI summary
A method of facilitating dormant small cell discovery in a wireless communications network including at least a small cell and a second cell includes changing, at the small cell, an operating state of the small cell from an active state to a dormant state, the dormant state being a state in which the small cell transmits discovery signals and does not transmit DL broadcast or DL control channels, the discovery signals being signals through which user equipments (UE)s discover the dormant small cell; sending, from the dormant small cell, a notification, the notification identifying, for at least the second cell, a duty cycle with which the first small cell will periodically transmit the discovery signals; and transmitting, from the dormant small, the discovery signals using a periodic transmission pattern that includes active portions and non-active portions defined by the duty cycle.