Minimum Frequency Separation for NR-U Dual Connectivity
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Solution Overview
Problem
In-device coexistence (IDC) problems arise when user equipment (UE) communicates using multiple unlicensed bands concurrently, leading to self-interference due to the close proximity of frequency bands and uncertainty in channel access, particularly in New Radio Unlicensed (NR-U) technology.
Innovation Solution
A master node communicates minimum frequency separation information to a secondary node to select channels that satisfy the required frequency separation, ensuring concurrent communications between the master and secondary nodes with the UE do not cause IDC issues, using methods such as slot and symbol timing synchronization and channel selection based on UE capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple unlicensed spectrum bands are used concurrently for carrier aggregation or dual connectivity, then spectral efficiency and data throughput are improved, but self-interference and in-device coexistence problems occur due to close frequency proximity
Solution Approach 1:
The patent changes the frequency parameter by selecting a second unlicensed band that maintains a minimum frequency separation from the first unlicensed band. This frequency parameter adjustment prevents self-interference while still enabling concurrent communication, thus resolving the contradiction between improving data throughput and avoiding self-interference.
Solution Approach 2:
The patent applies local quality by considering device-specific capabilities and requirements for minimum frequency separation. Different user equipment may have different susceptibility to self-interference, so the system tailors the frequency separation requirement to each device's local characteristics, allowing optimal use of multiple bands while preventing harmful interference.
2Adaptability or versatility
If unlicensed bands with close frequency proximity (e.g., 5 GHz and 6 GHz) are aggregated, then spectrum utilization is improved, but in-device coexistence problems arise due to insufficient frequency separation
Solution Approach 1:
The patent adjusts the frequency selection parameter by imposing a minimum frequency separation constraint when selecting the second unlicensed band. This parameter change ensures that bands with close proximity (like 5 GHz and 6 GHz) are not simultaneously used if they would cause self-interference, thereby maintaining communication reliability while still achieving good spectrum utilization through alternative band combinations.
Solution Approach 2:
The system incorporates feedback mechanisms where the network receives information about device capabilities and minimum frequency separation requirements, then uses this feedback to make informed decisions about which unlicensed bands to aggregate or use for dual connectivity, ensuring reliable communication while maximizing spectrum utilization.
Data Source
AI summary
A master node (MN) communicating with a UE using resource of a first band of unlicensed spectrum sends an addition request to a selected secondary node, to request resources for supporting the UE in a second band of unlicensed spectrum. The addition request includes minimum frequency separation information and optionally a baseline reference frequency. The minimum frequency separation information communicated in the addition request, indicates a minimum amount of frequency separation to be maintained between the communication resources in the first band of unlicensed spectrum used for communications with the UE and communication resource in the second band of unlicensed spectrum to be used for communications with the UE. The secondary node selects a channel within the second band of unlicensed spectrum to use for communications with the UE, which will satisfy the minimum frequency separation requirement communicated in the addition request and avoid IDC problems for the UE.