14 RLC suspension, stop and re-establishment procedures

3GPP44.160General Packet Radio Service (GPRS)Mobile Station (MS) - Base Station System (BSS) interfaceRadio Link Control / Medium Access Control (RLC/MAC) protocol Iu modeRelease 16TS

14.1 General

This sub-clause describes the following RLC procedures: suspend/resume, stop/continue and re-establishment. These procedures are requested by RRC (see 3GPP TS 44.118), and are applicable in NT-RLC only. Suspend/resume is used when e.g. ciphering parameters are changed. Stop/continue and re-establishment are used during e.g. RB reconfiguration.

14.2 Local suspend/resume function (NT-RLC)

The upper layers may suspend/resume a RLC entity. Suspension of a RLC entity is ordered through the CRLC‑SUSPEND-Req primitive (see sub-clause 4.3.3). Resumption is ordered through the CRLC-RESUME-Req primitive (see sub-clause 4.3.3).

When a RLC entity operating in unacknowledged mode is suspended by upper layers with the parameter N, the RLC entity shall:

– acknowledge the suspend request through the CRLC-SUSPEND-Conf primitive containing the current value of the send-state variable V(S);

– not send any RLC data block with a "Block Sequence Number" BSN(V(S)+N) modulo SNS;

– send Packet Uplink/Downlink Dummy control blocks on allocated radio resources if there is no other RLC/MAC control message to be sent.

When a RLC entity operating in acknowledged mode is suspended by upper layers with the parameter N, the RLC entity shall:

– acknowledge the suspend request through the CRLC-SUSPEND-Conf primitive containing the current value of the send-state variable V(S);

– not send any RLC data block with "Block Sequence Number" BSN  (V(S) + N) modulo SNS;

– proceed with retransmission procedures for RLC data blocks with BSN < (V(S) + N) modulo SNS as defined in sub-clauses 10.4.5 and 11.4.2;

– send Packet Uplink/Downlink Dummy control blocks on allocated radio resources if there is no other RLC/MAC control message or RLC data block to be sent.

When a RLC entity operating in unacknowledged mode is resumed by upper layers, the RLC entity shall:

– resume data transfer procedure.

When a RLC entity operating in acknowledged mode is resumed by upper layers, the RLC entity shall:

– resume data transfer procedure.

14.3 Stop/continue function (NT-RLC)

The RLC stop/continue procedure is applicable on DBPSCHs only.

The upper layer may stop/continue a RLC entity. Stop of a RLC entity is ordered through the CRLC-CONFIG-Req primitive (see sub-clause 4.3.3). Continuation of a RLC entity is ordered through the CRLC-CONFIG-Req primitive (see sub-clause 4.3.3).

When a uplink RLC entity is stopped, the mobile station shall pause the timers T3180 and T3182 if running. When a downlink RLC entity is stopped, the mobile station shall pause timer T3190 if running.

When an uplink RLC entity is continued, the mobile station shall continue the timers T3180 and T3182 if paused. When a downlink RLC entity is continued, the mobile station shall start timer T3190 if paused.

When a RLC entity is stopped by upper layers, the RLC entity shall:

– not submit any RLC data blocks to lower layer or accept any RLC data blocks;

– not submit any RLC/MAC control message to lower layer or accept any RLC/MAC control message;

– save all state variables.

When a RLC entity is continued by upper layers, the RLC entity shall:

– if the RLC entity is stopped:

– continue the data transmission and reception from the stored state variables.

– otherwise, if the RLC is not stopped:

– take no action.

14.4 RLC re-establishment function (NT-RLC)

The RLC re-establishment function is applicable in NT-RLC only, on DBPSCHs only.

The upper layers may re-establish a RLC entity. Re-establishment of a RLC entity is ordered through the RLC-CONFIG-Req primitive (see sub-clause 4.3.3).

When a RLC entity is re-established by upper layers, the RLC entity shall:

– reset the state variables to their initial value;

– set the configurable parameters (e.g. EGPRS RLC window size) to their configured value;

– set the hyper frame number (HFN) in UL and DL to the value configured by upper layers;

– if the RLC entity is operating in unacknowledged mode:

– if it is a receiving RLC entity:

– discard all RLC data blocks (PDUs).

– if it is a transmitting RLC entity:

– discard the RLC SDUs for which one or more segments have been submitted to the MAC layer.

– otherwise if the RLC entity is operating in acknowledged mode:

– discard all RLC data blocks (PDUs) and RLC/MAC control messages for this RLC entity.

Annex A (informative):
Change History

Change history
Date	Meeting	TDoc	CR	Rev	Cat	Subject/Comment	New version
2016-01		–	–	–	–	Rel-13 version created based on v12.0.0	13.0.0
2017-03	RP-75	–	–	–	–	Rel-14 version created based on v13.0.0	14.0.0
2018-06	RP-80	–	–	–	–	Rel-15 version created based on v14.0.0	15.0.0
2020-07	RP-88e	–	–	–	–	Upgrade to Rel-16 version without technical change	16.0.0