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The Abis interface consists of the protocols spoken between the BSC (Base Station Controller) and BTS (Base Transceiver Station).
It is specified in the following GSM standards:- 3GPP TS 08.51 (TS 48.051) : BSC-BTS Interface General Aspects
- 3GPP TS 08.52 (TS 48.052) : BSC-BTS Interface principles
- 3GPP TS 08.54 (TS 48.054) : BSC-BTS Layer 1: Structure of Physical Circuits
- 3GPP TS 08.56 (TS 48.056) : BSC-BTS Layer 2: Specification
- 3GPP TS 08.58 (TS 48.058) : BSC-BTS Layer 3: Specification
- This contains the specification of the RSL (Radio Signalling Link) on SAPI 0
- 3GPP TS 12.21 (TS 52.021) : Network Management procedures and messages on the A-bis interface
- This basically describes the OML (Organization and Maintenance Layer) on SAPI 62
- 3GPP TS 04.08 (TS 24.008) : Mobile radio interface layer 3 specification
- Description of the on-air (BTS-MS) layer 3, as carried in "DATA INDICATION" and other Abis messageS
RSL (Radio Signalling Link)¶
The RSL contains two types of messages- transparent messages (forwarded by BTS without interpretation or changes). T-bit in message discriminator 1
- non-transparent messages (messages sent between BSC and BTS)
furthermore, the messages are grouped into four main groups (see below).
All messages are transmitted using LAPD I frames, except for MEASUREMENT RESULT (UI). T-bit in message discriminator 0
Radio Link Layer Management¶
All messsages are prefixed by 6-byte header:- 1 byte message discriminator
- 1 byte message type
- 2 byte channel number
- 2 byte link identifier
- EST_IND: Link establishment indication (BTS->BSC)
- EST_REQ: Link establishment request (BSC->BTS)
- EST_CONF: Link establishment Confirmation (BTS->BSC)
- REL_IND: Link release indication (BTS->BSC)
- REL_REQ: Link release request (BSC->BTS)
- REL_CONF: Link release confirmation (BTS->BSC)
- DATA_REQ: Transmission of transparent L3 message in acknowledged mode (BSC->BTS)
- DATA_IND: Reception of transparent L3 message in acknowledged mode (BTS->BSC)
- UNIT_DATA_REQ: Transmission of transparent L3 message in unacknowledged mode (BSC->BTS)
- UNIT_DATA_IND: Reception of transparent L3 message in unacknowledged mode (BTS->BSC)
- ERROR_IND: Link error indication (BTS->BSC)
Dedicated Channel Management¶
All messsages are prefixed by 4-byte header:- 1 byte message discriminator
- 1 byte message type
- 2 byte channel number
- CHAN_ACTIV: Channel activation (BSC->BTS)
- CHAN_ACTIV_ACK: Channel activation acknowledgement (BTS->BSC)
- CHAN_ACTIV_NACK: Channel activation not acknowledged (BTS->BSC)
- MODE_MODIFY: Channel mode modify (BSC->BTS)
- MODE_MODIFY_ACK: Channel mode modify acknowledgement (BTS->BSC)
- MODE_MODIFY_NACK: Channel mode modify not acknowledged (BTS->BSC)
- HANDO_DET: Handover detection (BTS->BSC)
- ENCR_CMD: Start of Encryption (BSC->BTS)
- MEAS_RES: Measurement result (BTS->BSC)
- PREPROC_CONFIGURE: Configure pre-processed measurement report (BSC->BTS)
- PREPROC_MEAS_RES: Preprocessed measurement report (BTS->BSC)
- DEACT_SACCH: Deactivate SACCH (BSC->BTS)
- RF_CHAN_REL: Radio channel release (BSC->BTS)
- RF_CHAN_REL_ACK: Radio channel release ack (BTS->BSC)
- MS_POWER_CONTROL: MS power control (BSC->BTS)
- BS_POWER_CONTROL: Transmission power control (BSC->BTS)
- CONN_FAIL_IND: Connection failure indication (BTS->BSC)
- PHYS_CONTEXT_REQ: Physical context request (BSC->BTS)
- PHYS_CONTEXT_CONF: Physical context confirmation (BTS->BSC)
- SACCH_INFO_MODIFY: SACCH nformation modify (BSC->BTS)
- TALKER_DET: Talker detection (BTS->BSC)
- LISTENER_DET: Listener detection (BTS->BSC)
- REMOTE_CODEC_CONF: Remote codec configuration (BTS->BSC)
- RTD_REP: Round Trip Delay Report (BTS->BSC)
- PRE_HANDO_NOTIF: Pre-handover warning (BSC->BTS)
- CODEC_MOD_REQ: Multirate codec configuration change request (BSC->BTS)
- CODEC_MOD_ACK: Multirate codec configuration change acknowledge (BTS->BSC)
- CODEC_MOD_PERF: Multirate codec change performed (BTS->BSC)
- TFO_REPORT: TFO Report / AMR (BTS->BSC)
- TFO_MODIFICATION_REQ: TFO Modification Request (BSC->BTS)
Common Channel Management¶
All messsages are prefixed by 4-byte header:- 1 byte message discriminator
- 1 byte message type
- 2 byte channel number
- CHAN_RQS: Channel request by MS (BTS->BSC)
- PAG_CMD: Paging command (BSC->BTS)
- DELETE_IND: Delete indication (BTS->BSC)
- CCCH_LOAD_IND: CCCH load indication (BTS->BSC)
- BCCH_INFO: Broadcast information modify (BSC->BTS)
- SMS_BROADCAST_REQ: Short Message Cell Broadcast (BSC->BTS)
- SMS_BROADCAST_CMD: Short Message Cell Broadcast (BSC->BTS)
- IMM_ASS_CMD: Immediate Assign command (BSC->BTS)
- NOTIF_CMD: Notification (BSC->BTS)
TRX Management¶
All messsages are prefixed by 2-byte header:- 1 byte message discriminator
- 1 byte message type
- RF_RES_IND: Radio resource indication (BTS->BSC)
- SACCH_FILL: SACCH filling information modify (BSC->BTS)
- OVERLOAD: Flow control (BTS->BSC)
- ERROR_REPORT: Error reporting (BTS->BSC)
Updated by fixeria over 3 years ago · 6 revisions