SFN Offset Coordination in Dual Connectivity Wireless Systems
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Solution Overview
Problem
There is a need for a procedure to enable the setup, modification, or handover of a User Equipment (UE) bearer in wireless communication systems, where radio resources are provided by a Secondary eNB (SeNB) different from the radio network node hosting the RRC connection and the connection to the core network, specifically in heterogeneous networks with dual connectivity between Master eNB (MeNB) and SeNB.
Innovation Solution
A method involving the UE, MeNB, and SeNB to acquire and provide system information, including the System Frame Number (SFN) offset, through dedicated RRC signalling, allowing the UE to receive SFN from both MeNB and SeNB, and for MeNB and SeNB to coordinate and transmit SFN offsets, enabling accurate timing information without aligning SFNs between different eNBs, thereby reducing the need for radio resource alignment and broadcast of system information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SFN alignment between MeNB and SeNB is required, then timing accuracy is improved, but device complexity and radio resource overhead increase
Solution Approach 1:
The patent introduces an offset value as an intermediary parameter that mediates between the MeNB and SeNB SFN systems. Instead of requiring direct SFN alignment between the two eNBs, the offset value serves as a mediator that allows the UE to correctly interpret timing information from both sources, thereby maintaining timing accuracy without forcing system alignment
Solution Approach 2:
The patent changes the parameter representation by introducing an offset value that describes the temporal relationship between MeNB and SeNB SFNs. This parameter transformation allows the system to work with unsynchronized SFNs by mathematically adjusting the timing interpretation, rather than requiring the SFNs themselves to be synchronized
2Measurement precision
If SFN alignment between MeNB and SeNB is enforced, then timing consistency is improved, but loss of time for synchronization procedures increases
Solution Approach 1:
The offset value is determined and communicated to the UE in advance, before the UE needs to use it for timing calculations. This preliminary action allows the UE to be pre-equipped with the necessary timing relationship information, eliminating the need for real-time synchronization procedures when processing SeNB system information
3Loss of information
If SeNB broadcasts full system information including SFN, then information completeness is improved, but radio resource usage increases
Solution Approach 1:
The patent extracts only the essential timing information (offset value) from the complete system information that would otherwise need to be broadcast by the SeNB. By extracting and communicating only this critical parameter through more efficient means (e.g., backhaul or dedicated signaling), the system maintains information completeness for timing purposes while significantly reducing the radio resources required for SeNB broadcasting
4Measurement precision
If UE acquires SFN from both MeNB and SeNB, then timing accuracy is improved, but device complexity increases
Solution Approach 1:
The offset value acts as an intermediary that simplifies the UE's processing burden. Instead of requiring the UE to independently acquire and reconcile SFN information from both MeNB and SeNB, the offset value provides a direct mathematical relationship that the UE can apply to correctly interpret timing from either source, thereby maintaining timing accuracy while reducing processing complexity
Data Source
AI summary
A UE, a MeNB, a SeNB and respective methods performed thereby are provided. The UE, the MeNB, and the SeNB are operable in a wireless communication system, the wireless communication system being adapted to provide for dual connectivity between the SeNB and a UE, and between the UE and a MeNB. The method is performed for providing system information of the wireless communication system to the UE and for the UE to acquire the system information. The method performed by the UE comprises receiving (110), from the SeNB, a MIB of a cell of the SeNB; and acquiring (120) a System Frame Number, SFN, from the MIB.