What is radio link failure in LTE?
RLF is defined as Physical layer break. → Below reasons for RLF from UE side: The measured RSRP is too low (under a certain limit) It failed to decode PDCCH due to power signal quality (e.g, low RSRP, RSRQ) It failed to decode PDSCH due to power signal quality (e.g, low RSRP, RSRQ).
What is radio link failure in 5G?
Radio Link Failure (RLF) is a challenging problem in 5G networks as it may decrease communication reliability and increases latency. This is against the objectives of 5G, particularly for the ultra-Reliable Low Latency Communications (uRLLC) traffic class.
What causes radio link failure?
Following are the possible causes of radio link failure in wireless system. Failure at lower layers of stack i.e. at RF or physical layer due to higher frequency offset or time offset, poor carrier to interference conditions on the channels exchanged between UE and NB (i.e. base station).
What is SCG failure?
SCG Integrity Failure: When reconfiguration message received over SRB3 and its integrity check failed then UE trigger SCG failure with failure type set as srb3-IntegrityFailure. If same condition occur for the reconfiguration message received over SRB1 then UE trigger the re-establishment here.
How handover happens in LTE?
Abstract: Handover in LTE occurs when a device moves from the cell coverage serving it towards another; a process where the user established session must not be interrupted due to this cell change.
What is forward handover in LTE?
Handover related information is. exchanged between the UE and target eNB via the new radio path after. the UE context is fetched by the target eNB from the source eNB (thus, the usage of the term ‘forward’). Forward handover is successful even if.
What is MCG and SCG in LTE?
Abstract— Dual Connectivity in LTE network can significantly improve per-user throughput and mobility robustness by allowing users to be connected simultaneously to master cell group (MCG) and secondary cell group (SCG) via MeNB (master eNB) and SeNB (secondary eNB), respectively.
What happens when handover fails?
If the handover is rejected or canceled by the target radio or source radio respectively, all acquired resources will be released and cleared of the handover process both in radio and in core networks.
What is dual connectivity in LTE?
Dual Connectivity (DC) is an LTE Rel-12 feature that enables aggregation of two radio links with non-ideal backhaul without low-latency requirements. To allow this, the links are aggregated at the PDCP level, combining PDCP PDUs. This is different compared to CA (Carrier Aggregation) that combines MAC-layer blocks.
What are the common causes of radio link failure?
• Failure at lower layers of stack i.e. at RF or physical layer due to higher frequency offset or time offset, poor carrier to interference conditions on the channels exchanged between UE and NB (i.e. base station). Poor C/I occurs mainly due to power related issues. • Radio link failure during handover procedure or cell re-selection procedure.
What is radio link failure (RLF) in 5G NSA?
For the purpose of Radio Link Failure (RLF), the UE physical layer monitors the downlink radio link quality of the primary cell for indicating out-of-syn c / in-sync status indications to the higher layers. In 5G NSA EN-DC mode, RLF is declared separately for the MCG (E-UTRA LTE Cell) and for the SCG cells (NR).
How to recover radio link when UL data arrives from higher layer?
The most typical procedure is to go through RRC Connection Restablishement procedure. < Attemp to recover Radio Link while Out of SYNC (Radio Link Failure) – RRC Connection ReEstablishment > < When UL Data arrives from higher layer while Out of SYNC (Radio Link Failure) >
What is radio link monitoring (RLM)?
Radio Link Monitoring (RLM) is one of the important procedures in LTE. It is used to keep track of the radio link condition so that appropriate steps can be taken if Radio Link Failure (RLF) is declared. The figure below (taken from T-doc R2-133859) captures the RLM process: