RRC Sequences to wake up from FACH/PCH Following is generic sequence by which they can wake up from PCH to FACH or switch from FACH to DCH. This procedure can be triggered by Network or UE as shown below.

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. This protocol is specified by 3GPP in TS 25.331 [2] for UMTS, in TS 36.331 [3] for LTE and in TS 38.331 [4] for 5G New Radio. RRC messages are transported via the PDCP-Protocol.

The major role of RRC is to control(configure) all the Radio Resources (PHY, MAC, RLC, PDCP) to make it possible to communicate between UE and the base station (e.g, gNB, eNB, NB, BTS etc). In this page, I will give you the brief introduction to RRC in NR. In fact, RRC is a huge topic because it eventually get involved in whole protocol stack.

This page covers WCDMA UE RRC layer and explain RRC state diagram. It covers WCDMA RRC states idle and connected mode as per UMTS standard.There are cell_DCH, cell_FACH, cell_PCH and URA_PCH states when UE is in connected mode.

In LTE, the RRC_CONNECTED state has the benefits of CELL_FACH and to some extent CELL_PCH incorporated in it. Since in the downlink the scarce resource is the resource blocks, the downlink logical channels are always mapped onto shared transport channels (exhibiting the CELL_FACH properties).

CELL_FACH state is characterised by: No dedicated physical channel is allocated to the UE. The UE continuously monitors a FACH in the downlink. The UE is assigned a default common or shared transport channel in the uplink (e.g. RACH) that it can use anytime according to the access procedure for that transport channel.

We review RRC state transitions and study them in practice using our nov-el 3G Transition Triggering Tool (3G3T), focusing on the net-work configuration parameters that prompt these transitions.

— The UE continuously monitors a FACH in the downlink. — The UE is known on cell level according to the cell where the UE made a cell update. — Perform measurements and transmit measurement reports according to the measurement control information.

Jul 24, 2013 · FACH and RACH are shared channels with very low capacity. All the UEs in the CELL_FACH state have only these channels available (till Rel 6, In later releases 3GPP has also added HS-DSCH and EDCH in CELL-FACH state).

After establishing an RRC connection, the UE shifts from the idle mode to the connected mode: CELL_FACH or CELL_DCH state. The connected mode of UE is also called the RRC state of UE. It reflects the level of the UE connection and the transport channel that can be used by the UE.