6 Services provided to upper layers

25.3223GPPRadio Link Control (RLC) protocol specificationRelease 17TS

This clause describes the different services provided by RLC sublayer to upper layers. It also includes the mapping of RLC functions to different RLC services. For a detailed description of the RLC services see [3].

– Transparent data transfer Service:

The following functions are needed to support transparent data transfer:

– Segmentation and reassembly.

– Transfer of user data.

– SDU discard.

– Unacknowledged data transfer Service:

The following functions are needed to support unacknowledged data transfer:

– Segmentation and reassembly.

– Concatenation.

– Padding.

– Transfer of user data.

– Ciphering.

– Sequence number check.

– SDU discard.

– Out of sequence SDU delivery.

– Duplicate avoidance and reordering.

– Provisioning of sequence number.

– Acknowledged data transfer Service:

The following functions are needed to support acknowledged data transfer:

– Segmentation and reassembly.

– Concatenation.

– Padding.

– Transfer of user data.

– Error correction.

– In-sequence delivery of upper layer PDUs.

– Duplicate detection.

– Flow Control.

– Protocol error detection and recovery.

– Ciphering.

– SDU discard.

– Maintenance of QoS as defined by upper layers.

– Notification of unrecoverable errors.

6.1 Mapping of services/functions onto logical channels

The following tables show the applicability of services and functions to the logical channels in UL/DL and UE/UTRAN. A ‘+’ in a column denotes that the service/function is applicable for the logical channel in question whereas a ‘-‘ denotes that the service/function is not applicable.

Table 6.1: RLC modes and functions in UE uplink side

Service

Functions

CCCH

SHCCH

DCCH

DTCH

Transparent

Service

Applicability

+

+

–

+

Segmentation

–

–

–

+

Transfer of user data

+

+

–

+

SDU Discard

–

–

–

+

Unacknowledged

Service

Applicability

–

–

+

+

Segmentation

–

–

+

+

Concatenation

–

–

+

+

Padding

–

–

+

+

Transfer of user data

–

–

+

+

Ciphering

–

–

+

+

SDU Discard

–

–

+

+

Acknowledged

Service

Applicability

–

–

+

+

Segmentation

–

–

+

+

Concatenation

–

–

+

+

Padding

–

–

+

+

Transfer of user data

–

–

+

+

Flow Control

–

–

+

+

Error Correction

–

–

+

+

Protocol error detection & recovery

–

–

+

+

Ciphering

–

–

+

+

SDU Discard

–

–

+

+

Table 6.2: RLC modes and functions in UE downlink side

Service

Functions

BCCH

PCCH

SHCCH

CCCH

DCCH

DTCH

CTCH

MCCH

MTCH

MSCH

Transparent

Service

Applicability

+

+

–

–

+

+

–

–

–

–

Reassembly

–

–

–

–

+

+

–

–

–

–

Transfer of user data

+

+

–

–

+

+

–

–

–

–

Unacknowledged

Service

Applicability

–

–

+

+

+

+

+

+

+

+

Reassembly

–

–

+

+

+

+

+

+

+

+

Deciphering

–

–

–

–

+

+

–

–

–

–

Sequence number check

–

–

+

+

+

+

+

+

+

+

Transfer of user data

–

–

+

+

+

+

+

+

+

+

Duplicate avoidance and reordering

–

–

–

+

–

–

–

–

+

–

Out of sequence SDU delivery

–

–

–

–

–

–

–

+

–

–

Acknowledged

Service

Applicability

–

–

–

–

+

+

–

–

–

–

Reassembly

–

–

–

–

+

+

–

–

–

–

Error correction

–

–

–

–

+

+

–

–

–

–

Flow Control

–

–

–

–

+

+

–

–

–

–

In sequence delivery

–

–

–

–

+

+

–

–

–

–

Duplicate detection

–

–

–

–

+

+

–

–

–

–

Protocol error detection & recovery

–

–

–

–

+

+

–

–

–

–

Deciphering

–

–

–

–

+

+

–

–

–

–

Transfer of user data

–

–

–

–

+

+

–

–

–

–

SDU Discard

–

–

–

–

+

+

–

–

–

–

NOTE: Duplicate avoidance and reordering function is optional in UE.

Table 6.3: RLC modes and functions in UTRAN downlink side

Service

Functions

BCCH

PCCH

CCCH

SHCCH

DCCH

DTCH

CTCH

MCCH

MTCH

MSCH

Transparent

Service

Applicability

+

+

–

–

+

+

–

–

–

–

Segmentation

–

–

–

–

+

+

–

–

–

–

Transfer of user data

+

+

–

–

+

+

–

–

–

–

SDU Discard

–

–

–

–

+

+

–

–

–

–

Unacknowledged

Service

Applicability

–

–

+

+

+

+

+

+

+

+

Segmentation

–

–

+

+

+

+

+

+

+

+

Concatenation

–

–

+

+

+

+

+

+

+

+

Padding

–

–

+

+

+

+

+

+

+

+

Ciphering

–

–

–

–

+

+

–

–

–

–

Transfer of user data

–

–

+

+

+

+

+

+

+

+

SDU Discard

–

–

–

–

+

+

–

+

+

+

Acknowledged

Service

Applicability

–

–

–

–

+

+

–

–

–

–

Segmentation

–

–

–

–

+

+

–

–

–

–

Concatenation

–

–

–

–

+

+

–

–

–

–

Padding

–

–

–

–

+

+

–

–

–

–

Transfer of user data

–

–

–

–

+

+

–

–

–

–

Flow Control

–

–

–

–

+

+

–

–

–

–

Error Correction

–

–

–

–

+

+

–

–

–

–

Protocol error detection & recovery

–

–

–

–

+

+

–

–

–

–

Ciphering

–

–

–

–

+

+

–

–

–

–

SDU Discard

–

–

–

–

+

+

–

–

–

–

Table 6.4: RLC modes and functions in UTRAN uplink side

Service

Functions

CCCH

SHCCH

DCCH

DTCH

Transparent

Service

Applicability

+

+

–

+

Reassembly

–

–

–

+

Transfer of user data

+

+

–

+

Unacknowledged

Service

Applicability

–

–

+

+

Reassembly

–

–

+

+

Deciphering

–

–

+

+

Sequence number check

–

–

+

+

Transfer of user data

–

–

+

+

Acknowledged

Service

Applicability

–

–

+

+

Reassembly

–

–

+

+

Error correction

–

–

+

+

Flow Control

–

–

+

+

In sequence delivery

–

–

+

+

Duplicate detection

–

–

+

+

Protocol error detection & recovery

–

–

+

+

Deciphering

–

–

+

+

Transfer of user data

–

–

+

+

SDU Discard

–

–

+

+