Downlink Discovery Reference Signal Cyclic Shifts for Interference Mitigation
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Solution Overview
Problem
Next-generation wireless networks face challenges in achieving quick channel synchronization when user equipment handovers to small-cells transitioning from sleep mode to active mode, and in mitigating interference among downlink discovery reference signals from neighboring small-cells in dense clusters.
Innovation Solution
The method involves utilizing quasi-co-located antenna ports for discovery reference signals and cell-specific reference signals to facilitate faster channel synchronization, and applying different cyclic shifts to downlink discovery reference signals of neighboring base stations to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small-cells are deployed in dense clusters to increase data capacity, then network throughput capacity is improved, but interference among downlink discovery reference signals from neighboring small-cells increases
Solution Approach 1:
The patent segments the downlink discovery reference signal transmissions by assigning different cyclic shift values to different small-cells in the dense cluster. This segmentation in the cyclic domain allows multiple small-cells to transmit discovery signals simultaneously on the same time-frequency resources without causing harmful interference, thereby enabling dense small-cell deployment to increase network throughput capacity while mitigating signal interference
Solution Approach 2:
The patent changes the cyclic shift parameter of the discovery reference signals for different small-cells. By varying this parameter across neighboring small-cells, the system allows simultaneous transmissions without interference, resolving the contradiction between deploying dense small-cells for higher throughput and avoiding interference among their discovery signals
2Adaptability or versatility
If user equipment handovers to small-cells transitioning from sleep mode to active mode, then network adaptability is improved, but channel synchronization time increases
Solution Approach 1:
The patent applies preliminary action by having the user equipment utilize the quasi-co-located antenna port relationship to derive channel synchronization information from the discovery reference signal before the small-cell fully transitions to active mode. This preliminary synchronization acquisition reduces the time required for complete channel synchronization after handover, enabling faster network adaptability while minimizing synchronization time loss
Data Source
AI summary
User equipments can achieve quick channel synchronization when establishing a connection to base stations transitioning from a sleep mode to an active mode by using discovery resource signal (DRS) processing results and cell reference signal (CRS) processing results to establish channel synchronization with a CRS antenna port. More specifically, the user equipment may be notified that the CRS antenna port and DRS antenna port are quasi-co-located (QCL), and then use DRS processing results in conjunction with CRS processing results to obtain faster channel synchronization with a CRS antenna port. This may be particularly beneficial when the target BS is transitioned from a sleep mode to an active mode in order to accept a handover of the user equipment.