Multi-BTS with handover » History » Version 10
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 | 8 | ipse | * '''bts''' - BTS number in a config file, always 0 for a BTS configuration file, 0..n for the NITB configuration file |
34 | 3 | * '''band''' - the band in which the BTS will operate |
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35 | 1 | * '''ipa unit-id''' - each BTS must use a unique value |
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36 | * '''oml remote-ip''' - this is the BSC IP address |
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37 | |||
38 | The example configuration that follows is for two BTS both on the GSM900 band. |
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39 | |||
40 | ==== BTS 0 ==== |
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41 | |||
42 | 3 | Find the aforementioned parameters and ensure that they are correctly set. |
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43 | |||
44 | 1 | {{{ |
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45 | bts 0 |
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46 | band GSM900 |
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47 | ipa unit-id 1801 0 |
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48 | 3 | oml remote-ip 172.30.1.10 |
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49 | ... |
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50 | }}} |
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51 | |||
52 | ==== BTS 1 ==== |
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53 | |||
54 | Ensure that the second BTS has a different '''ipa unit-id''' configured from the first. |
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55 | |||
56 | 1 | {{{ |
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57 | 8 | ipse | bts 0 |
58 | 3 | band GSM900 |
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59 | ipa unit-id 1802 0 |
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60 | oml remote-ip 172.30.1.10 |
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61 | ... |
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62 | }}} |
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63 | |||
64 | === BSC configuration === |
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65 | |||
66 | 7 | There are a number of BSC/NITB parameters that you must pay particular attention to: |
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67 | 3 | ||
68 | * '''BTS ''n''' |
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69 | * '''band''' - as configured in the BTS |
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70 | * '''base_station_id_code''' - should be unique in location area |
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71 | * '''ip.access unit_id''' - as configured in the BTS |
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72 | * '''trx ''n'' |
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73 | 5 | * '''arfcn''' - this must be frequencies that you have a licence for and unique across all neighbouring BTS |
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74 | 3 | * '''neighbor-list mode automatic''' |
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75 | |||
76 | 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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77 | 3 | ||
78 | {{{ |
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79 | bts 0 |
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80 | ... |
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81 | band GSM900 |
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82 | ... |
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83 | base_station_id_code 63 |
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84 | ... |
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85 | ip.access unit_id 1801 0 |
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86 | ... |
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87 | neighbor-list mode automatic |
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88 | ... |
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89 | trx 0 |
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90 | rf_locked 0 |
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91 | arfcn 74 |
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92 | ... |
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93 | trx 1 |
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94 | rf_locked 0 |
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95 | arfcn 84 |
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96 | ... |
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97 | }}} |
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98 | |||
99 | 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: |
100 | 1 | ||
101 | 3 | {{{ |
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102 | 10 | bts 1 |
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103 | 3 | ... |
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104 | band GSM900 |
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105 | ... |
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106 | base_station_id_code 62 |
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107 | ... |
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108 | ip.access unit_id 1802 0 |
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109 | ... |
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110 | neighbor-list mode automatic |
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111 | ... |
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112 | trx 0 |
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113 | rf_locked 0 |
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114 | arfcn 111 |
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115 | ... |
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116 | trx 1 |
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117 | rf_locked 0 |
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118 | 1 | arfcn 122 |
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119 | 3 | ... |
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120 | }}} |
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121 | |||
122 | 4 | ipse | For details of all the configuration options please see the [wiki:osmo-nitb_VTY NITB VTY reference]. |
123 | 3 | ||
124 | ==== Handover ==== |
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125 | |||
126 | The following parameters must also be configured in order to enable handover: |
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127 | |||
128 | * '''handover 1''' |
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129 | * ''Enable in-call handover between multiple BTS.'' |
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130 | |||
131 | * '''handover window rxlev averaging 10''' |
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132 | * ''The receive level of the serving cell should be averaged over 10 SACCH frames.'' |
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133 | |||
134 | * '''handover window rxqual averaging 1''' |
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135 | * ''The receive quality of the serving cell should be averaged over 1 SACCH frame.'' |
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136 | |||
137 | * '''handover window rxlev neighbor averaging 10''' |
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138 | * ''The Rx Level of a neighbour cell should be averaged over 10 SACCH frames.'' |
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139 | |||
140 | * '''handover power budget interval 6''' |
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141 | * ''Consider performing a power budget (Rx level) handover every 6 SACCH frames.'' |
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142 | |||
143 | * '''handover power budget hysteresis 3''' |
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144 | * ''Set hysteresis (prevents continuous handover back and forth) to 3.'' |
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145 | |||
146 | * '''handover maximum distance 9999''' |
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147 | * ''When the distance from the BTS is greater than 9999 attempt a distance handover.'' |
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148 | |||
149 | 7 | These parameters must be set within the '''network''' section of the BSC/NITB configuration: |
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150 | 3 | ||
151 | {{{ |
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152 | network |
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153 | network country code 1 |
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154 | ... |
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155 | handover 1 |
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156 | handover window rxlev averaging 10 |
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157 | handover window rxqual averaging 1 |
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158 | handover window rxlev neighbor averaging 10 |
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159 | handover power budget interval 6 |
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160 | handover power budget hysteresis 3 |
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161 | handover maximum distance 9999 |
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162 | }}} |
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163 | |||
164 | Values can be tuned to modify the behaviour of handover. |
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165 | |||
166 | 9 | ipse | === Testing handover === |
167 | |||
168 | To test handover you have two options: |
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169 | |||
170 | 1. Physically move a phone to trigger handover decision. |
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171 | 2. Use "subscriber ID handover BTS_NR" command in the NITB VTY to force handover. |
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172 | 3 | === Complete configurations === |
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173 | |||
174 | 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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175 | 3 | ||
176 | ==== BTS 0 ==== |
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177 | |||
178 | {{{ |
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179 | bts 0 |
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180 | band GSM900 |
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181 | ipa unit-id 1801 0 |
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182 | oml remote-ip 172.30.1.10 |
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183 | 1 | rtp jitter-buffer 0 |
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184 | paging lifetime 0 |
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185 | gsmtap-sapi bcch |
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186 | gsmtap-sapi ccch |
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187 | gsmtap-sapi rach |
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188 | gsmtap-sapi agch |
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189 | gsmtap-sapi pch |
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190 | gsmtap-sapi sdcch |
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191 | gsmtap-sapi pacch |
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192 | gsmtap-sapi pdtch |
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193 | gsmtap-sapi sacch |
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194 | fn-advance 20 |
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195 | ms-power-loop -10 |
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196 | timing-advance-loop |
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197 | trx 0 |
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198 | rxgain 12 |
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199 | power 0 |
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200 | trx 1 |
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201 | rxgain 12 |
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202 | power 0 |
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203 | }}} |
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204 | |||
205 | ==== BTS 1 ==== |
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206 | |||
207 | {{{ |
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208 | 8 | ipse | bts 0 |
209 | 1 | band GSM900 |
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210 | ipa unit-id 1802 0 |
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211 | 3 | oml remote-ip 172.30.1.10 |
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212 | 1 | rtp jitter-buffer 0 |
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213 | paging lifetime 0 |
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214 | gsmtap-sapi bcch |
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215 | gsmtap-sapi ccch |
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216 | gsmtap-sapi rach |
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217 | gsmtap-sapi agch |
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218 | gsmtap-sapi pch |
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219 | gsmtap-sapi sdcch |
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220 | gsmtap-sapi pacch |
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221 | gsmtap-sapi pdtch |
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222 | gsmtap-sapi sacch |
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223 | fn-advance 20 |
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224 | ms-power-loop -10 |
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225 | timing-advance-loop |
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226 | trx 0 |
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227 | rxgain 12 |
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228 | power 0 |
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229 | trx 1 |
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230 | rxgain 12 |
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231 | power 0 |
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232 | }}} |
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233 | |||
234 | ==== OpenBSC NITB ==== |
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235 | 7 | ||
236 | 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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237 | 1 | ||
238 | {{{ |
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239 | ! |
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240 | ! OpenBSC (UNKNOWN) configuration saved from vty |
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241 | !! |
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242 | password foo |
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243 | ! |
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244 | line vty |
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245 | no login |
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246 | ! |
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247 | e1_input |
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248 | e1_line 0 driver ipa |
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249 | e1_line 0 port 0 |
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250 | no e1_line 0 keepalive |
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251 | network |
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252 | network country code 1 |
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253 | mobile network code 1 |
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254 | short name Osmocom |
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255 | long name Osmocom |
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256 | auth policy accept-all |
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257 | location updating reject cause 13 |
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258 | encryption a5 0 |
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259 | neci 1 |
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260 | paging any use tch 0 |
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261 | rrlp mode none |
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262 | mm info 1 |
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263 | handover 1 |
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264 | handover window rxlev averaging 10 |
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265 | handover window rxqual averaging 1 |
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266 | handover window rxlev neighbor averaging 10 |
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267 | handover power budget interval 6 |
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268 | handover power budget hysteresis 3 |
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269 | handover maximum distance 9999 |
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270 | timer t3101 10 |
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271 | timer t3103 0 |
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272 | timer t3105 0 |
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273 | timer t3107 0 |
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274 | timer t3109 4 |
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275 | timer t3111 0 |
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276 | timer t3113 60 |
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277 | timer t3115 0 |
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278 | timer t3117 0 |
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279 | timer t3119 0 |
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280 | timer t3122 10 |
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281 | timer t3141 0 |
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282 | dtx-used 0 |
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283 | subscriber-keep-in-ram 0 |
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284 | bts 0 |
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285 | type sysmobts |
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286 | band GSM900 |
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287 | cell_identity 0 |
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288 | location_area_code 1 |
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289 | base_station_id_code 63 |
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290 | ms max power 15 |
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291 | cell reselection hysteresis 4 |
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292 | rxlev access min 0 |
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293 | periodic location update 30 |
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294 | radio-link-timeout 32 |
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295 | channel allocator ascending |
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296 | rach tx integer 9 |
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297 | rach max transmission 7 |
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298 | channel-descrption attach 1 |
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299 | channel-descrption bs-pa-mfrms 5 |
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300 | channel-descrption bs-ag-blks-res 1 |
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301 | ip.access unit_id 1801 0 |
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302 | oml ip.access stream_id 255 line 0 |
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303 | neighbor-list mode automatic |
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304 | gprs mode none |
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305 | no force-combined-si |
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306 | trx 0 |
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307 | rf_locked 0 |
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308 | arfcn 74 |
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309 | nominal power 23 |
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310 | max_power_red 0 |
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311 | rsl e1 tei 0 |
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312 | timeslot 0 |
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313 | phys_chan_config CCCH+SDCCH4 |
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314 | hopping enabled 0 |
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315 | timeslot 1 |
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316 | phys_chan_config SDCCH8 |
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317 | hopping enabled 0 |
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318 | timeslot 2 |
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319 | phys_chan_config TCH/F |
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320 | hopping enabled 0 |
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321 | timeslot 3 |
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322 | phys_chan_config TCH/F |
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323 | hopping enabled 0 |
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324 | timeslot 4 |
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325 | phys_chan_config TCH/F |
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326 | hopping enabled 0 |
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327 | timeslot 5 |
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328 | phys_chan_config TCH/F |
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329 | hopping enabled 0 |
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330 | timeslot 6 |
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331 | phys_chan_config TCH/F |
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332 | hopping enabled 0 |
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333 | timeslot 7 |
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334 | phys_chan_config TCH/F |
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335 | hopping enabled 0 |
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336 | trx 1 |
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337 | rf_locked 0 |
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338 | arfcn 84 |
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339 | nominal power 23 |
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340 | max_power_red 0 |
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341 | rsl e1 tei 0 |
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342 | timeslot 0 |
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343 | phys_chan_config TCH/F |
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344 | hopping enabled 0 |
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345 | timeslot 1 |
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346 | phys_chan_config TCH/F |
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347 | hopping enabled 0 |
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348 | timeslot 2 |
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349 | phys_chan_config TCH/F |
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350 | hopping enabled 0 |
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351 | timeslot 3 |
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352 | phys_chan_config TCH/F |
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353 | hopping enabled 0 |
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354 | timeslot 4 |
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355 | phys_chan_config TCH/F |
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356 | hopping enabled 0 |
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357 | timeslot 5 |
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358 | phys_chan_config TCH/F |
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359 | hopping enabled 0 |
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360 | timeslot 6 |
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361 | phys_chan_config TCH/F |
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362 | hopping enabled 0 |
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363 | timeslot 7 |
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364 | phys_chan_config TCH/F |
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365 | hopping enabled 0 |
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366 | bts 1 |
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367 | type sysmobts |
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368 | band GSM900 |
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369 | cell_identity 0 |
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370 | location_area_code 1 |
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371 | base_station_id_code 62 |
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372 | ms max power 15 |
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373 | cell reselection hysteresis 4 |
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374 | rxlev access min 0 |
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375 | periodic location update 30 |
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376 | radio-link-timeout 32 |
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377 | channel allocator ascending |
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378 | rach tx integer 9 |
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379 | rach max transmission 7 |
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380 | channel-descrption attach 1 |
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381 | channel-descrption bs-pa-mfrms 5 |
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382 | channel-descrption bs-ag-blks-res 1 |
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383 | ip.access unit_id 1802 0 |
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384 | oml ip.access stream_id 255 line 0 |
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385 | neighbor-list mode automatic |
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386 | gprs mode none |
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387 | no force-combined-si |
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388 | trx 0 |
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389 | rf_locked 0 |
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390 | arfcn 111 |
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391 | nominal power 23 |
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392 | max_power_red 0 |
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393 | rsl e1 tei 0 |
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394 | timeslot 0 |
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395 | phys_chan_config CCCH+SDCCH4 |
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396 | hopping enabled 0 |
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397 | timeslot 1 |
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398 | phys_chan_config SDCCH8 |
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399 | hopping enabled 0 |
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400 | timeslot 2 |
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401 | phys_chan_config TCH/F |
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402 | hopping enabled 0 |
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403 | timeslot 3 |
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404 | phys_chan_config TCH/F |
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405 | hopping enabled 0 |
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406 | timeslot 4 |
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407 | phys_chan_config TCH/F |
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408 | hopping enabled 0 |
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409 | timeslot 5 |
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410 | phys_chan_config TCH/F |
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411 | hopping enabled 0 |
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412 | timeslot 6 |
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413 | phys_chan_config TCH/F |
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414 | hopping enabled 0 |
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415 | timeslot 7 |
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416 | phys_chan_config TCH/F |
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417 | hopping enabled 0 |
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418 | trx 1 |
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419 | rf_locked 0 |
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420 | arfcn 122 |
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421 | nominal power 23 |
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422 | max_power_red 0 |
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423 | rsl e1 tei 0 |
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424 | timeslot 0 |
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425 | phys_chan_config TCH/F |
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426 | hopping enabled 0 |
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427 | timeslot 1 |
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428 | phys_chan_config TCH/F |
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429 | hopping enabled 0 |
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430 | timeslot 2 |
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431 | phys_chan_config TCH/F |
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432 | hopping enabled 0 |
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433 | timeslot 3 |
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434 | 2 | phys_chan_config TCH/F |
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435 | 1 | hopping enabled 0 |
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436 | timeslot 4 |
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437 | phys_chan_config TCH/F |
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438 | hopping enabled 0 |
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439 | timeslot 5 |
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440 | phys_chan_config TCH/F |
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441 | hopping enabled 0 |
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442 | timeslot 6 |
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443 | phys_chan_config TCH/F |
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444 | hopping enabled 0 |
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445 | timeslot 7 |
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446 | phys_chan_config TCH/F |
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447 | hopping enabled 0 |
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448 | }}} |