Abis Interface » History » Revision 2
Revision 1 (laforge, 02/19/2016 10:47 PM) → Revision 2/6 (laforge, 02/19/2016 10:47 PM)
The Abis protocol is the protocol spoken between the BSC (Base Station Controller) and BTS (Base Transceiver Station). It is specified in the following GSM standards: * 3GPP TS 08.51 : BSC-BTS Interface General Aspects * 3GPP TS 08.52 : BSC-BTS Interface principles * 3GPP TS 08.54 : BSC-BTS Layer 1: Structure of Physical Circuits * 3GPP TS 08.56 : BSC-BTS Layer 2: Specification * 3GPP TS 08.58 : BSC-BTS Layer 3: Specification * This contains the specification of the RSL (Radio Signalling Link) on SAPI 0 * 3GPP TS 21.21 : Network Management procedures and messages on the A-bis interface * This basically describes the OML (Organization and Maintenance Layer) on SAPI 62 == 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 changes) * 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 The actual message types are: * 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 The actual message types are: * 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 The actual message types are: * 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 The actual message types are: * 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)
