Multi-BTS with handover » History » Version 7
Anonymous, 02/19/2016 10:48 PM
| 1 | 1 | [[PageOutline]] |
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| 2 | 3 | == Configuring OpenBSC with muiltiple BTS and in-call handover == |
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| 3 | 1 | ||
| 4 | 3 | === Prerequisites === |
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| 5 | 1 | ||
| 6 | 7 | It is assumed that you already have a functioning BSC/NITB, and two or more BTS available. |
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| 7 | 3 | ||
| 8 | 1 | Note that if you are using BTS based on OsmoBTS/OsmoTRX handover requires: |
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| 9 | |||
| 10 | * osmo-bts package version >= fw-5 (this [http://cgit.osmocom.org/osmo-bts/commit/?h=fairwaves/master&id=a6ad0b44ae45a2fd51b6a55507e8295605431e92 fix] is included) |
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| 11 | * osmo-trx package version >= 0.2.0 (this [http://cgit.osmocom.org/osmo-trx/commit/?h=fairwaves/master&id=19c392df82fe7acd303e4340059c87c432623881 patch] is included) |
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| 12 | |||
| 13 | === Example network architecture === |
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| 14 | |||
| 15 | 7 | In this example we have one system running the BSC/NITB software and two BTS that are built on the [wiki:OsmoBTS] software. |
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| 16 | 1 | ||
| 17 | {{{ |
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| 18 | #!graphviz |
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| 19 | digraph G { |
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| 20 | rankdir = LR; |
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| 21 | BSC -> BTS0 [ label = "A-bis" dir=both ]; |
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| 22 | BSC -> BTS1 [ label = "A-bis" dir=both ]; |
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| 23 | BSC [ shape = square label = "BSC\n172.30.1.10" ]; |
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| 24 | BTS0 [ shape = square label = "BTS 0\n172.30.1.11" ]; |
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| 25 | BTS1 [ shape = square label = "BTS 1\n172.30.1.12" ]; |
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| 26 | } |
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| 27 | }}} |
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| 28 | |||
| 29 | === BTS configuration === |
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| 30 | |||
| 31 | 3 | There are three OsmoBTS parameters in particular which must be correctly configured: |
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| 32 | 1 | ||
| 33 | 3 | * '''band''' - the band in which the BTS will operate |
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| 34 | 1 | * '''ipa unit-id''' - each BTS must use a unique value |
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| 35 | * '''oml remote-ip''' - this is the BSC IP address |
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| 36 | |||
| 37 | The example configuration that follows is for two BTS both on the GSM900 band. |
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| 38 | |||
| 39 | ==== BTS 0 ==== |
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| 40 | |||
| 41 | 3 | Find the aforementioned parameters and ensure that they are correctly set. |
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| 42 | |||
| 43 | 1 | {{{ |
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| 44 | bts 0 |
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| 45 | band GSM900 |
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| 46 | ipa unit-id 1801 0 |
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| 47 | 3 | oml remote-ip 172.30.1.10 |
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| 48 | ... |
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| 49 | }}} |
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| 50 | |||
| 51 | ==== BTS 1 ==== |
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| 52 | |||
| 53 | Ensure that the second BTS has a different '''ipa unit-id''' configured from the first. |
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| 54 | |||
| 55 | {{{ |
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| 56 | bts 1 |
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| 57 | band GSM900 |
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| 58 | ipa unit-id 1802 0 |
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| 59 | oml remote-ip 172.30.1.10 |
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| 60 | ... |
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| 61 | }}} |
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| 62 | |||
| 63 | === BSC configuration === |
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| 64 | |||
| 65 | 7 | There are a number of BSC/NITB parameters that you must pay particular attention to: |
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| 66 | 3 | ||
| 67 | * '''BTS ''n''' |
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| 68 | * '''band''' - as configured in the BTS |
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| 69 | * '''base_station_id_code''' - should be unique in location area |
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| 70 | * '''ip.access unit_id''' - as configured in the BTS |
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| 71 | * '''trx ''n'' |
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| 72 | 5 | * '''arfcn''' - this must be frequencies that you have a licence for and unique across all neighbouring BTS |
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| 73 | 3 | * '''neighbor-list mode automatic''' |
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| 74 | |||
| 75 | 7 | Configure the first BTS within the BSC/NITB, ensuring that you have set the correct '''band''' and '''ip.access unit_id''', and an appropriate '''arfcn''' for each TRX. |
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| 76 | 3 | ||
| 77 | {{{ |
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| 78 | bts 0 |
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| 79 | ... |
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| 80 | band GSM900 |
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| 81 | ... |
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| 82 | base_station_id_code 63 |
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| 83 | ... |
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| 84 | ip.access unit_id 1801 0 |
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| 85 | ... |
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| 86 | neighbor-list mode automatic |
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| 87 | ... |
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| 88 | trx 0 |
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| 89 | rf_locked 0 |
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| 90 | arfcn 74 |
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| 91 | ... |
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| 92 | trx 1 |
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| 93 | rf_locked 0 |
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| 94 | arfcn 84 |
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| 95 | ... |
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| 96 | }}} |
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| 97 | |||
| 98 | 4 | ipse | Next configure the second BTS, ensuring that a different '''base_station_id_code''' is used this time, once again the correct '''ip.access unit_id''' is set, and an appropriate '''arfcn''' for each TRX: |
| 99 | 3 | ||
| 100 | {{{ |
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| 101 | bts 1 |
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| 102 | ... |
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| 103 | band GSM900 |
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| 104 | ... |
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| 105 | base_station_id_code 62 |
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| 106 | ... |
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| 107 | ip.access unit_id 1802 0 |
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| 108 | ... |
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| 109 | neighbor-list mode automatic |
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| 110 | ... |
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| 111 | trx 0 |
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| 112 | rf_locked 0 |
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| 113 | arfcn 111 |
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| 114 | ... |
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| 115 | trx 1 |
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| 116 | rf_locked 0 |
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| 117 | 1 | arfcn 122 |
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| 118 | 3 | ... |
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| 119 | }}} |
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| 120 | |||
| 121 | 4 | ipse | For details of all the configuration options please see the [wiki:osmo-nitb_VTY NITB VTY reference]. |
| 122 | 3 | ||
| 123 | ==== Handover ==== |
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| 124 | |||
| 125 | The following parameters must also be configured in order to enable handover: |
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| 126 | |||
| 127 | * '''handover 1''' |
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| 128 | * ''Enable in-call handover between multiple BTS.'' |
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| 129 | |||
| 130 | * '''handover window rxlev averaging 10''' |
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| 131 | * ''The receive level of the serving cell should be averaged over 10 SACCH frames.'' |
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| 132 | |||
| 133 | * '''handover window rxqual averaging 1''' |
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| 134 | * ''The receive quality of the serving cell should be averaged over 1 SACCH frame.'' |
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| 135 | |||
| 136 | * '''handover window rxlev neighbor averaging 10''' |
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| 137 | * ''The Rx Level of a neighbour cell should be averaged over 10 SACCH frames.'' |
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| 138 | |||
| 139 | * '''handover power budget interval 6''' |
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| 140 | * ''Consider performing a power budget (Rx level) handover every 6 SACCH frames.'' |
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| 141 | |||
| 142 | * '''handover power budget hysteresis 3''' |
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| 143 | * ''Set hysteresis (prevents continuous handover back and forth) to 3.'' |
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| 144 | |||
| 145 | * '''handover maximum distance 9999''' |
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| 146 | * ''When the distance from the BTS is greater than 9999 attempt a distance handover.'' |
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| 147 | |||
| 148 | 7 | These parameters must be set within the '''network''' section of the BSC/NITB configuration: |
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| 149 | 3 | ||
| 150 | {{{ |
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| 151 | network |
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| 152 | network country code 1 |
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| 153 | ... |
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| 154 | handover 1 |
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| 155 | handover window rxlev averaging 10 |
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| 156 | handover window rxqual averaging 1 |
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| 157 | handover window rxlev neighbor averaging 10 |
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| 158 | handover power budget interval 6 |
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| 159 | handover power budget hysteresis 3 |
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| 160 | handover maximum distance 9999 |
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| 161 | }}} |
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| 162 | |||
| 163 | Values can be tuned to modify the behaviour of handover. |
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| 164 | |||
| 165 | === Complete configurations === |
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| 166 | |||
| 167 | 7 | Complete example configs are included here for reference only and should not be used without modification, unless you happen to have a licence for those particular frequencies. |
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| 168 | 3 | ||
| 169 | ==== BTS 0 ==== |
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| 170 | |||
| 171 | {{{ |
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| 172 | bts 0 |
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| 173 | band GSM900 |
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| 174 | ipa unit-id 1801 0 |
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| 175 | oml remote-ip 172.30.1.10 |
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| 176 | 1 | rtp jitter-buffer 0 |
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| 177 | paging lifetime 0 |
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| 178 | gsmtap-sapi bcch |
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| 179 | gsmtap-sapi ccch |
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| 180 | gsmtap-sapi rach |
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| 181 | gsmtap-sapi agch |
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| 182 | gsmtap-sapi pch |
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| 183 | gsmtap-sapi sdcch |
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| 184 | gsmtap-sapi pacch |
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| 185 | gsmtap-sapi pdtch |
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| 186 | gsmtap-sapi sacch |
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| 187 | fn-advance 20 |
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| 188 | ms-power-loop -10 |
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| 189 | timing-advance-loop |
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| 190 | trx 0 |
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| 191 | rxgain 12 |
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| 192 | power 0 |
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| 193 | trx 1 |
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| 194 | rxgain 12 |
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| 195 | power 0 |
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| 196 | }}} |
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| 197 | |||
| 198 | ==== BTS 1 ==== |
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| 199 | |||
| 200 | {{{ |
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| 201 | bts 1 |
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| 202 | band GSM900 |
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| 203 | ipa unit-id 1802 0 |
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| 204 | 3 | oml remote-ip 172.30.1.10 |
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| 205 | 1 | rtp jitter-buffer 0 |
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| 206 | paging lifetime 0 |
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| 207 | gsmtap-sapi bcch |
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| 208 | gsmtap-sapi ccch |
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| 209 | gsmtap-sapi rach |
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| 210 | gsmtap-sapi agch |
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| 211 | gsmtap-sapi pch |
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| 212 | gsmtap-sapi sdcch |
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| 213 | gsmtap-sapi pacch |
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| 214 | gsmtap-sapi pdtch |
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| 215 | gsmtap-sapi sacch |
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| 216 | fn-advance 20 |
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| 217 | ms-power-loop -10 |
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| 218 | timing-advance-loop |
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| 219 | trx 0 |
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| 220 | rxgain 12 |
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| 221 | power 0 |
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| 222 | trx 1 |
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| 223 | rxgain 12 |
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| 224 | power 0 |
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| 225 | }}} |
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| 226 | |||
| 227 | ==== OpenBSC NITB ==== |
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| 228 | 7 | ||
| 229 | Note that whilst this configuration is for NITB operation, the updates describe above could equally be applied to OpenBSC configured in BSC-only mode and with an external MSC etc. |
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| 230 | 1 | ||
| 231 | {{{ |
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| 232 | ! |
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| 233 | ! OpenBSC (UNKNOWN) configuration saved from vty |
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| 234 | !! |
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| 235 | password foo |
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| 236 | ! |
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| 237 | line vty |
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| 238 | no login |
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| 239 | ! |
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| 240 | e1_input |
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| 241 | e1_line 0 driver ipa |
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| 242 | e1_line 0 port 0 |
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| 243 | no e1_line 0 keepalive |
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| 244 | network |
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| 245 | network country code 1 |
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| 246 | mobile network code 1 |
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| 247 | short name Osmocom |
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| 248 | long name Osmocom |
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| 249 | auth policy accept-all |
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| 250 | location updating reject cause 13 |
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| 251 | encryption a5 0 |
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| 252 | neci 1 |
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| 253 | paging any use tch 0 |
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| 254 | rrlp mode none |
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| 255 | mm info 1 |
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| 256 | handover 1 |
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| 257 | handover window rxlev averaging 10 |
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| 258 | handover window rxqual averaging 1 |
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| 259 | handover window rxlev neighbor averaging 10 |
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| 260 | handover power budget interval 6 |
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| 261 | handover power budget hysteresis 3 |
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| 262 | handover maximum distance 9999 |
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| 263 | timer t3101 10 |
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| 264 | timer t3103 0 |
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| 265 | timer t3105 0 |
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| 266 | timer t3107 0 |
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| 267 | timer t3109 4 |
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| 268 | timer t3111 0 |
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| 269 | timer t3113 60 |
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| 270 | timer t3115 0 |
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| 271 | timer t3117 0 |
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| 272 | timer t3119 0 |
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| 273 | timer t3122 10 |
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| 274 | timer t3141 0 |
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| 275 | dtx-used 0 |
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| 276 | subscriber-keep-in-ram 0 |
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| 277 | bts 0 |
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| 278 | type sysmobts |
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| 279 | band GSM900 |
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| 280 | cell_identity 0 |
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| 281 | location_area_code 1 |
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| 282 | base_station_id_code 63 |
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| 283 | ms max power 15 |
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| 284 | cell reselection hysteresis 4 |
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| 285 | rxlev access min 0 |
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| 286 | periodic location update 30 |
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| 287 | radio-link-timeout 32 |
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| 288 | channel allocator ascending |
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| 289 | rach tx integer 9 |
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| 290 | rach max transmission 7 |
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| 291 | channel-descrption attach 1 |
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| 292 | channel-descrption bs-pa-mfrms 5 |
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| 293 | channel-descrption bs-ag-blks-res 1 |
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| 294 | ip.access unit_id 1801 0 |
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| 295 | oml ip.access stream_id 255 line 0 |
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| 296 | neighbor-list mode automatic |
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| 297 | gprs mode none |
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| 298 | no force-combined-si |
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| 299 | trx 0 |
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| 300 | rf_locked 0 |
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| 301 | arfcn 74 |
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| 302 | nominal power 23 |
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| 303 | max_power_red 0 |
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| 304 | rsl e1 tei 0 |
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| 305 | timeslot 0 |
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| 306 | phys_chan_config CCCH+SDCCH4 |
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| 307 | hopping enabled 0 |
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| 308 | timeslot 1 |
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| 309 | phys_chan_config SDCCH8 |
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| 310 | hopping enabled 0 |
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| 311 | timeslot 2 |
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| 312 | phys_chan_config TCH/F |
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| 313 | hopping enabled 0 |
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| 314 | timeslot 3 |
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| 315 | phys_chan_config TCH/F |
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| 316 | hopping enabled 0 |
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| 317 | timeslot 4 |
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| 318 | phys_chan_config TCH/F |
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| 319 | hopping enabled 0 |
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| 320 | timeslot 5 |
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| 321 | phys_chan_config TCH/F |
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| 322 | hopping enabled 0 |
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| 323 | timeslot 6 |
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| 324 | phys_chan_config TCH/F |
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| 325 | hopping enabled 0 |
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| 326 | timeslot 7 |
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| 327 | phys_chan_config TCH/F |
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| 328 | hopping enabled 0 |
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| 329 | trx 1 |
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| 330 | rf_locked 0 |
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| 331 | arfcn 84 |
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| 332 | nominal power 23 |
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| 333 | max_power_red 0 |
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| 334 | rsl e1 tei 0 |
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| 335 | timeslot 0 |
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| 336 | phys_chan_config TCH/F |
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| 337 | hopping enabled 0 |
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| 338 | timeslot 1 |
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| 339 | phys_chan_config TCH/F |
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| 340 | hopping enabled 0 |
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| 341 | timeslot 2 |
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| 342 | phys_chan_config TCH/F |
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| 343 | hopping enabled 0 |
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| 344 | timeslot 3 |
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| 345 | phys_chan_config TCH/F |
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| 346 | hopping enabled 0 |
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| 347 | timeslot 4 |
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| 348 | phys_chan_config TCH/F |
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| 349 | hopping enabled 0 |
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| 350 | timeslot 5 |
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| 351 | phys_chan_config TCH/F |
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| 352 | hopping enabled 0 |
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| 353 | timeslot 6 |
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| 354 | phys_chan_config TCH/F |
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| 355 | hopping enabled 0 |
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| 356 | timeslot 7 |
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| 357 | phys_chan_config TCH/F |
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| 358 | hopping enabled 0 |
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| 359 | bts 1 |
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| 360 | type sysmobts |
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| 361 | band GSM900 |
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| 362 | cell_identity 0 |
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| 363 | location_area_code 1 |
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| 364 | base_station_id_code 62 |
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| 365 | ms max power 15 |
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| 366 | cell reselection hysteresis 4 |
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| 367 | rxlev access min 0 |
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| 368 | periodic location update 30 |
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| 369 | radio-link-timeout 32 |
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| 370 | channel allocator ascending |
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| 371 | rach tx integer 9 |
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| 372 | rach max transmission 7 |
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| 373 | channel-descrption attach 1 |
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| 374 | channel-descrption bs-pa-mfrms 5 |
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| 375 | channel-descrption bs-ag-blks-res 1 |
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| 376 | ip.access unit_id 1802 0 |
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| 377 | oml ip.access stream_id 255 line 0 |
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| 378 | neighbor-list mode automatic |
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| 379 | gprs mode none |
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| 380 | no force-combined-si |
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| 381 | trx 0 |
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| 382 | rf_locked 0 |
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| 383 | arfcn 111 |
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| 384 | nominal power 23 |
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| 385 | max_power_red 0 |
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| 386 | rsl e1 tei 0 |
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| 387 | timeslot 0 |
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| 388 | phys_chan_config CCCH+SDCCH4 |
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| 389 | hopping enabled 0 |
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| 390 | timeslot 1 |
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| 391 | phys_chan_config SDCCH8 |
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| 392 | hopping enabled 0 |
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| 393 | timeslot 2 |
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| 394 | phys_chan_config TCH/F |
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| 395 | hopping enabled 0 |
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| 396 | timeslot 3 |
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| 397 | phys_chan_config TCH/F |
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| 398 | hopping enabled 0 |
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| 399 | timeslot 4 |
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| 400 | phys_chan_config TCH/F |
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| 401 | hopping enabled 0 |
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| 402 | timeslot 5 |
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| 403 | phys_chan_config TCH/F |
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| 404 | hopping enabled 0 |
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| 405 | timeslot 6 |
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| 406 | phys_chan_config TCH/F |
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| 407 | hopping enabled 0 |
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| 408 | timeslot 7 |
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| 409 | phys_chan_config TCH/F |
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| 410 | hopping enabled 0 |
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| 411 | trx 1 |
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| 412 | rf_locked 0 |
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| 413 | arfcn 122 |
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| 414 | nominal power 23 |
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| 415 | max_power_red 0 |
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| 416 | rsl e1 tei 0 |
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| 417 | timeslot 0 |
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| 418 | phys_chan_config TCH/F |
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| 419 | hopping enabled 0 |
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| 420 | timeslot 1 |
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| 421 | phys_chan_config TCH/F |
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| 422 | hopping enabled 0 |
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| 423 | timeslot 2 |
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| 424 | phys_chan_config TCH/F |
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| 425 | hopping enabled 0 |
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| 426 | timeslot 3 |
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| 427 | 2 | phys_chan_config TCH/F |
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| 428 | 1 | hopping enabled 0 |
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| 429 | timeslot 4 |
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| 430 | phys_chan_config TCH/F |
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| 431 | hopping enabled 0 |
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| 432 | timeslot 5 |
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| 433 | phys_chan_config TCH/F |
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| 434 | hopping enabled 0 |
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| 435 | timeslot 6 |
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| 436 | phys_chan_config TCH/F |
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| 437 | hopping enabled 0 |
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| 438 | timeslot 7 |
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| 439 | phys_chan_config TCH/F |
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| 440 | hopping enabled 0 |
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| 441 | }}} |
