Abis Interface » History » Version 5
laforge, 12/09/2017 10:13 AM
1 | 5 | laforge | The Abis interface consists of the protocols spoken between the BSC (Base Station Controller) and BTS (Base Transceiver Station). |
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2 | 1 | laforge | |
3 | It is specified in the following GSM standards: |
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4 | 4 | laforge | * 3GPP TS 08.51 : BSC-BTS Interface General Aspects |
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 | 5 | laforge | * 3GPP TS 12.21 : Network Management procedures and messages on the A-bis interface |
11 | 4 | laforge | ** This basically describes the OML (Organization and Maintenance Layer) on SAPI 62 |
12 | * 3GPP TS 04.08 : Mobile radio interface layer 3 specification |
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13 | ** Description of the on-air (BTS-MS) layer 3, as carried in "DATA INDICATION" and other Abis messageS |
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14 | 1 | laforge | |
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16 | 4 | laforge | h2. RSL (Radio Signalling Link) |
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19 | 1 | laforge | The RSL contains two types of messages |
20 | 4 | laforge | * transparent messages (forwarded by BTS without interpretation or changes). T-bit in message discriminator == 1 |
21 | * non-transparent messages (messages sent between BSC and BTS) |
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22 | 1 | laforge | |
23 | furthermore, the messages are grouped into four main groups (see below). |
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24 | |||
25 | All messages are transmitted using LAPD I frames, except for MEASUREMENT RESULT (UI). T-bit in message discriminator == 0 |
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28 | 4 | laforge | h3. Radio Link Layer Management |
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31 | 1 | laforge | All messsages are prefixed by 6-byte header: |
32 | 4 | laforge | * 1 byte message discriminator |
33 | * 1 byte message type |
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34 | * 2 byte channel number |
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35 | * 2 byte link identifier |
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36 | 1 | laforge | |
37 | The actual message types are: |
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38 | 4 | laforge | * EST_IND: Link establishment indication (BTS->BSC) |
39 | * EST_REQ: Link establishment request (BSC->BTS) |
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40 | * EST_CONF: Link establishment Confirmation (BTS->BSC) |
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41 | * REL_IND: Link release indication (BTS->BSC) |
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42 | * REL_REQ: Link release request (BSC->BTS) |
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43 | * REL_CONF: Link release confirmation (BTS->BSC) |
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44 | * DATA_REQ: Transmission of transparent L3 message in acknowledged mode (BSC->BTS) |
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45 | * DATA_IND: Reception of transparent L3 message in acknowledged mode (BTS->BSC) |
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46 | * UNIT_DATA_REQ: Transmission of transparent L3 message in unacknowledged mode (BSC->BTS) |
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47 | * UNIT_DATA_IND: Reception of transparent L3 message in unacknowledged mode (BTS->BSC) |
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48 | * ERROR_IND: Link error indication (BTS->BSC) |
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49 | 1 | laforge | |
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51 | 4 | laforge | h3. Dedicated Channel Management |
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54 | 1 | laforge | All messsages are prefixed by 4-byte header: |
55 | 4 | laforge | * 1 byte message discriminator |
56 | * 1 byte message type |
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57 | * 2 byte channel number |
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58 | 1 | laforge | |
59 | The actual message types are: |
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60 | 4 | laforge | * CHAN_ACTIV: Channel activation (BSC->BTS) |
61 | * CHAN_ACTIV_ACK: Channel activation acknowledgement (BTS->BSC) |
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62 | * CHAN_ACTIV_NACK: Channel activation not acknowledged (BTS->BSC) |
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63 | * MODE_MODIFY: Channel mode modify (BSC->BTS) |
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64 | * MODE_MODIFY_ACK: Channel mode modify acknowledgement (BTS->BSC) |
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65 | * MODE_MODIFY_NACK: Channel mode modify not acknowledged (BTS->BSC) |
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66 | * HANDO_DET: Handover detection (BTS->BSC) |
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67 | * ENCR_CMD: Start of Encryption (BSC->BTS) |
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68 | * MEAS_RES: Measurement result (BTS->BSC) |
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69 | * PREPROC_CONFIGURE: Configure pre-processed measurement report (BSC->BTS) |
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70 | * PREPROC_MEAS_RES: Preprocessed measurement report (BTS->BSC) |
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71 | * DEACT_SACCH: Deactivate SACCH (BSC->BTS) |
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72 | * RF_CHAN_REL: Radio channel release (BSC->BTS) |
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73 | * RF_CHAN_REL_ACK: Radio channel release ack (BTS->BSC) |
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74 | * MS_POWER_CONTROL: MS power control (BSC->BTS) |
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75 | * BS_POWER_CONTROL: Transmission power control (BSC->BTS) |
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76 | * CONN_FAIL_IND: Connection failure indication (BTS->BSC) |
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77 | * PHYS_CONTEXT_REQ: Physical context request (BSC->BTS) |
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78 | * PHYS_CONTEXT_CONF: Physical context confirmation (BTS->BSC) |
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79 | * SACCH_INFO_MODIFY: SACCH nformation modify (BSC->BTS) |
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80 | * TALKER_DET: Talker detection (BTS->BSC) |
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81 | * LISTENER_DET: Listener detection (BTS->BSC) |
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82 | * REMOTE_CODEC_CONF: Remote codec configuration (BTS->BSC) |
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83 | * RTD_REP: Round Trip Delay Report (BTS->BSC) |
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84 | * PRE_HANDO_NOTIF: Pre-handover warning (BSC->BTS) |
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85 | * CODEC_MOD_REQ: Multirate codec configuration change request (BSC->BTS) |
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86 | * CODEC_MOD_ACK: Multirate codec configuration change acknowledge (BTS->BSC) |
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87 | * CODEC_MOD_PERF: Multirate codec change performed (BTS->BSC) |
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88 | * TFO_REPORT: TFO Report / AMR (BTS->BSC) |
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89 | * TFO_MODIFICATION_REQ: TFO Modification Request (BSC->BTS) |
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90 | 1 | laforge | |
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92 | 4 | laforge | h3. Common Channel Management |
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95 | 2 | laforge | All messsages are prefixed by 4-byte header: |
96 | 4 | laforge | * 1 byte message discriminator |
97 | * 1 byte message type |
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98 | * 2 byte channel number |
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99 | 1 | laforge | |
100 | The actual message types are: |
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101 | 4 | laforge | * CHAN_RQS: Channel request by MS (BTS->BSC) |
102 | * PAG_CMD: Paging command (BSC->BTS) |
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103 | * DELETE_IND: Delete indication (BTS->BSC) |
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104 | * CCCH_LOAD_IND: CCCH load indication (BTS->BSC) |
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105 | * BCCH_INFO: Broadcast information modify (BSC->BTS) |
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106 | * SMS_BROADCAST_REQ: Short Message Cell Broadcast (BSC->BTS) |
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107 | * SMS_BROADCAST_CMD: Short Message Cell Broadcast (BSC->BTS) |
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108 | * IMM_ASS_CMD: Immediate Assign command (BSC->BTS) |
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109 | * NOTIF_CMD: Notification (BSC->BTS) |
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110 | 1 | laforge | |
111 | 4 | laforge | |
112 | h3. TRX Management |
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114 | 1 | laforge | All messsages are prefixed by 2-byte header: |
115 | 4 | laforge | * 1 byte message discriminator |
116 | * 1 byte message type |
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117 | 1 | laforge | |
118 | The actual message types are: |
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119 | 4 | laforge | * RF_RES_IND: Radio resource indication (BTS->BSC) |
120 | * SACCH_FILL: SACCH filling information modify (BSC->BTS) |
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121 | * OVERLOAD: Flow control (BTS->BSC) |
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122 | * ERROR_REPORT: Error reporting (BTS->BSC) |