Abis Interface » History » Version 2
laforge, 02/19/2016 10:47 PM
| 1 | 1 | laforge | The Abis protocol is the protocol spoken between the BSC (Base Station Controller) and BTS (Base Transceiver Station). |
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| 2 | |||
| 3 | It is specified in the following GSM standards: |
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| 4 | * 3GPP TS 08.51 : BSC-BTS Interface General Aspects |
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| 5 | * 3GPP TS 08.52 : BSC-BTS Interface principles |
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| 6 | * 3GPP TS 08.54 : BSC-BTS Layer 1: Structure of Physical Circuits |
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| 7 | * 3GPP TS 08.56 : BSC-BTS Layer 2: Specification |
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| 8 | * 3GPP TS 08.58 : BSC-BTS Layer 3: Specification |
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| 9 | * This contains the specification of the RSL (Radio Signalling Link) on SAPI 0 |
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| 10 | * 3GPP TS 21.21 : Network Management procedures and messages on the A-bis interface |
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| 11 | * This basically describes the OML (Organization and Maintenance Layer) on SAPI 62 |
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| 12 | |||
| 13 | |||
| 14 | == RSL (Radio Signalling Link) == |
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| 15 | |||
| 16 | The RSL contains two types of messages |
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| 17 | 2 | laforge | * transparent messages (forwarded by BTS without interpretation or changes). T-bit in message discriminator == 1 |
| 18 | 1 | laforge | * non-transparent messages (messages sent between BSC and BTS) |
| 19 | |||
| 20 | furthermore, the messages are grouped into four main groups (see below). |
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| 21 | 2 | laforge | |
| 22 | All messages are transmitted using LAPD I frames, except for MEASUREMENT RESULT (UI). T-bit in message discriminator == 0 |
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| 23 | 1 | laforge | |
| 24 | === Radio Link Layer Management === |
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| 25 | 2 | laforge | |
| 26 | All messsages are prefixed by 6-byte header: |
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| 27 | * 1 byte message discriminator |
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| 28 | * 1 byte message type |
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| 29 | * 2 byte channel number |
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| 30 | * 2 byte link identifier |
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| 31 | |||
| 32 | The actual message types are: |
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| 33 | 1 | laforge | * EST_IND: Link establishment indication (BTS->BSC) |
| 34 | * EST_REQ: Link establishment request (BSC->BTS) |
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| 35 | * EST_CONF: Link establishment Confirmation (BTS->BSC) |
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| 36 | * REL_IND: Link release indication (BTS->BSC) |
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| 37 | * REL_REQ: Link release request (BSC->BTS) |
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| 38 | * REL_CONF: Link release confirmation (BTS->BSC) |
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| 39 | * DATA_REQ: Transmission of transparent L3 message in acknowledged mode (BSC->BTS) |
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| 40 | * DATA_IND: Reception of transparent L3 message in acknowledged mode (BTS->BSC) |
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| 41 | * UNIT_DATA_REQ: Transmission of transparent L3 message in unacknowledged mode (BSC->BTS) |
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| 42 | * UNIT_DATA_IND: Reception of transparent L3 message in unacknowledged mode (BTS->BSC) |
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| 43 | * ERROR_IND: Link error indication (BTS->BSC) |
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| 44 | |||
| 45 | === Dedicated Channel Management === |
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| 46 | 2 | laforge | |
| 47 | All messsages are prefixed by 4-byte header: |
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| 48 | * 1 byte message discriminator |
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| 49 | * 1 byte message type |
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| 50 | * 2 byte channel number |
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| 51 | |||
| 52 | The actual message types are: |
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| 53 | 1 | laforge | * CHAN_ACTIV: Channel activation (BSC->BTS) |
| 54 | * CHAN_ACTIV_ACK: Channel activation acknowledgement (BTS->BSC) |
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| 55 | * CHAN_ACTIV_NACK: Channel activation not acknowledged (BTS->BSC) |
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| 56 | * MODE_MODIFY: Channel mode modify (BSC->BTS) |
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| 57 | * MODE_MODIFY_ACK: Channel mode modify acknowledgement (BTS->BSC) |
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| 58 | * MODE_MODIFY_NACK: Channel mode modify not acknowledged (BTS->BSC) |
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| 59 | * HANDO_DET: Handover detection (BTS->BSC) |
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| 60 | * ENCR_CMD: Start of Encryption (BSC->BTS) |
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| 61 | * MEAS_RES: Measurement result (BTS->BSC) |
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| 62 | * PREPROC_CONFIGURE: Configure pre-processed measurement report (BSC->BTS) |
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| 63 | * PREPROC_MEAS_RES: Preprocessed measurement report (BTS->BSC) |
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| 64 | * DEACT_SACCH: Deactivate SACCH (BSC->BTS) |
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| 65 | * RF_CHAN_REL: Radio channel release (BSC->BTS) |
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| 66 | * RF_CHAN_REL_ACK: Radio channel release ack (BTS->BSC) |
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| 67 | * MS_POWER_CONTROL: MS power control (BSC->BTS) |
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| 68 | * BS_POWER_CONTROL: Transmission power control (BSC->BTS) |
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| 69 | * CONN_FAIL_IND: Connection failure indication (BTS->BSC) |
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| 70 | * PHYS_CONTEXT_REQ: Physical context request (BSC->BTS) |
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| 71 | * PHYS_CONTEXT_CONF: Physical context confirmation (BTS->BSC) |
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| 72 | * SACCH_INFO_MODIFY: SACCH nformation modify (BSC->BTS) |
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| 73 | * TALKER_DET: Talker detection (BTS->BSC) |
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| 74 | * LISTENER_DET: Listener detection (BTS->BSC) |
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| 75 | * REMOTE_CODEC_CONF: Remote codec configuration (BTS->BSC) |
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| 76 | * RTD_REP: Round Trip Delay Report (BTS->BSC) |
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| 77 | * PRE_HANDO_NOTIF: Pre-handover warning (BSC->BTS) |
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| 78 | * CODEC_MOD_REQ: Multirate codec configuration change request (BSC->BTS) |
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| 79 | * CODEC_MOD_ACK: Multirate codec configuration change acknowledge (BTS->BSC) |
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| 80 | * CODEC_MOD_PERF: Multirate codec change performed (BTS->BSC) |
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| 81 | * TFO_REPORT: TFO Report / AMR (BTS->BSC) |
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| 82 | * TFO_MODIFICATION_REQ: TFO Modification Request (BSC->BTS) |
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| 83 | |||
| 84 | === Common Channel Management === |
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| 85 | 2 | laforge | |
| 86 | All messsages are prefixed by 4-byte header: |
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| 87 | * 1 byte message discriminator |
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| 88 | * 1 byte message type |
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| 89 | * 2 byte channel number |
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| 90 | |||
| 91 | The actual message types are: |
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| 92 | 1 | laforge | * CHAN_RQS: Channel request by MS (BTS->BSC) |
| 93 | * PAG_CMD: Paging command (BSC->BTS) |
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| 94 | * DELETE_IND: Delete indication (BTS->BSC) |
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| 95 | * CCCH_LOAD_IND: CCCH load indication (BTS->BSC) |
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| 96 | * BCCH_INFO: Broadcast information modify (BSC->BTS) |
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| 97 | * SMS_BROADCAST_REQ: Short Message Cell Broadcast (BSC->BTS) |
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| 98 | * SMS_BROADCAST_CMD: Short Message Cell Broadcast (BSC->BTS) |
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| 99 | * IMM_ASS_CMD: Immediate Assign command (BSC->BTS) |
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| 100 | * NOTIF_CMD: Notification (BSC->BTS) |
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| 101 | |||
| 102 | === TRX Management === |
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| 103 | 2 | laforge | All messsages are prefixed by 2-byte header: |
| 104 | * 1 byte message discriminator |
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| 105 | * 1 byte message type |
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| 106 | |||
| 107 | The actual message types are: |
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| 108 | 1 | laforge | * RF_RES_IND: Radio resource indication (BTS->BSC) |
| 109 | * SACCH_FILL: SACCH filling information modify (BSC->BTS) |
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| 110 | * OVERLOAD: Flow control (BTS->BSC) |
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| 111 | * ERROR_REPORT: Error reporting (BTS->BSC) |
