Multi-BTS with handover » History » Version 5
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 | 3 | It is assumed that you already have a functioning [wiki:osmo-nitb OpenBSC NITB] and two or more BTS available. |
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7 | |||
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 | In this example we have one system running the NITB software and two BTS that are built on the [wiki:OsmoBTS] software. |
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16 | |||
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 | There are a number of OpenBSC NITB parameters that you must pay particular attention to: |
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66 | |||
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 | 4 | ipse | Configure the first BTS within OpenBSC NITB, ensuring that you have set the correct '''band''' and '''ip.access unit_id''', and an appropriate '''arfcn''' for each TRX. |
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 | These parameters must be set within the '''network''' section of the OpenBSC NITB configuration: |
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149 | |||
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 | Complete example configs are included for reference and should not be used without modification, unless you happen to have a licence for those particular frequencies. |
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168 | |||
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 | 3 | ==== OpenBSC NITB ==== |
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228 | 1 | ||
229 | {{{ |
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230 | ! |
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231 | ! OpenBSC (UNKNOWN) configuration saved from vty |
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232 | !! |
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233 | password foo |
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234 | ! |
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235 | line vty |
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236 | no login |
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237 | ! |
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238 | e1_input |
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239 | e1_line 0 driver ipa |
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240 | e1_line 0 port 0 |
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241 | no e1_line 0 keepalive |
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242 | network |
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243 | network country code 1 |
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244 | mobile network code 1 |
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245 | short name Osmocom |
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246 | long name Osmocom |
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247 | auth policy accept-all |
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248 | location updating reject cause 13 |
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249 | encryption a5 0 |
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250 | neci 1 |
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251 | paging any use tch 0 |
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252 | rrlp mode none |
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253 | mm info 1 |
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254 | handover 1 |
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255 | handover window rxlev averaging 10 |
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256 | handover window rxqual averaging 1 |
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257 | handover window rxlev neighbor averaging 10 |
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258 | handover power budget interval 6 |
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259 | handover power budget hysteresis 3 |
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260 | handover maximum distance 9999 |
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261 | timer t3101 10 |
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262 | timer t3103 0 |
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263 | timer t3105 0 |
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264 | timer t3107 0 |
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265 | timer t3109 4 |
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266 | timer t3111 0 |
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267 | timer t3113 60 |
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268 | timer t3115 0 |
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269 | timer t3117 0 |
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270 | timer t3119 0 |
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271 | timer t3122 10 |
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272 | timer t3141 0 |
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273 | dtx-used 0 |
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274 | subscriber-keep-in-ram 0 |
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275 | bts 0 |
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276 | type sysmobts |
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277 | band GSM900 |
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278 | cell_identity 0 |
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279 | location_area_code 1 |
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280 | base_station_id_code 63 |
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281 | ms max power 15 |
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282 | cell reselection hysteresis 4 |
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283 | rxlev access min 0 |
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284 | periodic location update 30 |
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285 | radio-link-timeout 32 |
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286 | channel allocator ascending |
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287 | rach tx integer 9 |
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288 | rach max transmission 7 |
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289 | channel-descrption attach 1 |
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290 | channel-descrption bs-pa-mfrms 5 |
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291 | channel-descrption bs-ag-blks-res 1 |
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292 | ip.access unit_id 1801 0 |
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293 | oml ip.access stream_id 255 line 0 |
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294 | neighbor-list mode automatic |
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295 | gprs mode none |
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296 | no force-combined-si |
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297 | trx 0 |
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298 | rf_locked 0 |
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299 | arfcn 74 |
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300 | nominal power 23 |
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301 | max_power_red 0 |
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302 | rsl e1 tei 0 |
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303 | timeslot 0 |
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304 | phys_chan_config CCCH+SDCCH4 |
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305 | hopping enabled 0 |
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306 | timeslot 1 |
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307 | phys_chan_config SDCCH8 |
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308 | hopping enabled 0 |
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309 | timeslot 2 |
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310 | phys_chan_config TCH/F |
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311 | hopping enabled 0 |
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312 | timeslot 3 |
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313 | phys_chan_config TCH/F |
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314 | hopping enabled 0 |
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315 | timeslot 4 |
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316 | phys_chan_config TCH/F |
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317 | hopping enabled 0 |
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318 | timeslot 5 |
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319 | phys_chan_config TCH/F |
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320 | hopping enabled 0 |
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321 | timeslot 6 |
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322 | phys_chan_config TCH/F |
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323 | hopping enabled 0 |
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324 | timeslot 7 |
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325 | phys_chan_config TCH/F |
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326 | hopping enabled 0 |
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327 | trx 1 |
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328 | rf_locked 0 |
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329 | arfcn 84 |
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330 | nominal power 23 |
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331 | max_power_red 0 |
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332 | rsl e1 tei 0 |
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333 | timeslot 0 |
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334 | phys_chan_config TCH/F |
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335 | hopping enabled 0 |
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336 | timeslot 1 |
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337 | phys_chan_config TCH/F |
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338 | hopping enabled 0 |
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339 | timeslot 2 |
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340 | phys_chan_config TCH/F |
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341 | hopping enabled 0 |
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342 | timeslot 3 |
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343 | phys_chan_config TCH/F |
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344 | hopping enabled 0 |
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345 | timeslot 4 |
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346 | phys_chan_config TCH/F |
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347 | hopping enabled 0 |
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348 | timeslot 5 |
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349 | phys_chan_config TCH/F |
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350 | hopping enabled 0 |
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351 | timeslot 6 |
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352 | phys_chan_config TCH/F |
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353 | hopping enabled 0 |
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354 | timeslot 7 |
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355 | phys_chan_config TCH/F |
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356 | hopping enabled 0 |
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357 | bts 1 |
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358 | type sysmobts |
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359 | band GSM900 |
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360 | cell_identity 0 |
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361 | location_area_code 1 |
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362 | base_station_id_code 62 |
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363 | ms max power 15 |
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364 | cell reselection hysteresis 4 |
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365 | rxlev access min 0 |
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366 | periodic location update 30 |
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367 | radio-link-timeout 32 |
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368 | channel allocator ascending |
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369 | rach tx integer 9 |
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370 | rach max transmission 7 |
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371 | channel-descrption attach 1 |
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372 | channel-descrption bs-pa-mfrms 5 |
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373 | channel-descrption bs-ag-blks-res 1 |
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374 | ip.access unit_id 1802 0 |
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375 | oml ip.access stream_id 255 line 0 |
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376 | neighbor-list mode automatic |
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377 | gprs mode none |
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378 | no force-combined-si |
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379 | trx 0 |
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380 | rf_locked 0 |
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381 | arfcn 111 |
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382 | nominal power 23 |
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383 | max_power_red 0 |
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384 | rsl e1 tei 0 |
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385 | timeslot 0 |
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386 | phys_chan_config CCCH+SDCCH4 |
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387 | hopping enabled 0 |
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388 | timeslot 1 |
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389 | phys_chan_config SDCCH8 |
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390 | hopping enabled 0 |
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391 | timeslot 2 |
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392 | phys_chan_config TCH/F |
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393 | hopping enabled 0 |
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394 | timeslot 3 |
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395 | phys_chan_config TCH/F |
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396 | hopping enabled 0 |
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397 | timeslot 4 |
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398 | phys_chan_config TCH/F |
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399 | hopping enabled 0 |
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400 | timeslot 5 |
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401 | phys_chan_config TCH/F |
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402 | hopping enabled 0 |
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403 | timeslot 6 |
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404 | phys_chan_config TCH/F |
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405 | hopping enabled 0 |
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406 | timeslot 7 |
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407 | phys_chan_config TCH/F |
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408 | hopping enabled 0 |
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409 | trx 1 |
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410 | rf_locked 0 |
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411 | arfcn 122 |
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412 | nominal power 23 |
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413 | max_power_red 0 |
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414 | rsl e1 tei 0 |
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415 | timeslot 0 |
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416 | phys_chan_config TCH/F |
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417 | hopping enabled 0 |
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418 | timeslot 1 |
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419 | phys_chan_config TCH/F |
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420 | hopping enabled 0 |
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421 | timeslot 2 |
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422 | phys_chan_config TCH/F |
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423 | hopping enabled 0 |
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424 | timeslot 3 |
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425 | 2 | phys_chan_config TCH/F |
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426 | 1 | hopping enabled 0 |
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427 | timeslot 4 |
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428 | phys_chan_config TCH/F |
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429 | hopping enabled 0 |
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430 | timeslot 5 |
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431 | phys_chan_config TCH/F |
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432 | hopping enabled 0 |
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433 | timeslot 6 |
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434 | phys_chan_config TCH/F |
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435 | hopping enabled 0 |
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436 | timeslot 7 |
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437 | phys_chan_config TCH/F |
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438 | hopping enabled 0 |
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439 | }}} |