What are the reasons for RLF in LTE?

When UE Report RLF?

• 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 LTE RLF?

Abstract: In LTE and NR, the user equipment initiates a recovery procedure when a radio link failure (RLF) is declared. A shorter RLF timer T312 is introduced to speed up the recovery from an RLF and lower the outage time during a handover.

What is the conditions of re establishment?

The UE initiates the RRC CONNECTION RE-ESTABLISHMENT procedure when one of the following conditions is met: Upon detecting radio link failure; or. Upon handover failure; or. Upon mobility from E-UTRA failure; or.

What is RLF in 5G?

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-sync / 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).

What is N310 in LTE?

When the UE detects a few consecutive “out-of-sync” indications, known as N310, it initiates a network-configured RLF timer T310. By default, the number of N310, 200 ms interval, out-of-sync pulses is 1. Otherwise, T311 starts when the UE tries to re-establish the RRC connection with the strongest eNB signal.

What is MCG and SCG in 5g?

MCG ( Master Cell Group ) Bearer. SCG ( Secondary Cell Group ) Bearer.

What is the reason of handover failure in LTE?

Figure 1 – LTE Backward Handover Procedure RLF handover is UE-based mobility and provides a recovery mechanism when the backward handover signaling with the source cell partially fails due to poor radio conditions.

What is RRC connection in LTE?

The Radio Resource Control (RRC) protocol is used in UMTS, LTE and 5G on the Air interface. It is a layer 3 (Network Layer) protocol used between UE and Base Station. The operation of the RRC is guided by a state machine which defines certain specific states that a UE may be present in.

What is S1 mode in LTE?

The S1 interface connects the eNB to the EPC. It can be split into control-plane (S1-MME) and user-plane (S1-U). The S1-MME is a signaling interface which supports a set of functions and procedures between the eNB and the MME. The role of S1-U is to transport user data packets between the eNB and the S-GW.

What is S1 handover in LTE?

An S1 handover is a fallback for scenarios where X2 interface is not available. The MME and the SGW are involved during the handover procedure. An interesting part of LTE S1 handovers is the indirect tunnel that is established to carry the downlink data during the handover process.

What is timer in LTE?

Function at Start/Stop/Expiry. T300. >>Starts at the RRC connection REQ transmit. >>Stops at the Receipt of RRC connection setup or reject message OR at the cell reselection time OR upon abortion of connection establishment by Higher layers (L2/L3).