Multi-BTS with handover » History » Version 1
Anonymous, 02/19/2016 10:48 PM
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2 | == Configuring OpenBSC for use with more than one BTS == |
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3 | |||
4 | This short how-to guide assumes that you already have a functioning [wiki:osmo-nitb] and two or more BTS available. |
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5 | |||
6 | Note that if you are using BTS based on OsmoBTS/OsmoTRX handover requires: |
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7 | |||
8 | * 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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9 | * 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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10 | |||
11 | === Example network architecture === |
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12 | |||
13 | 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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14 | |||
15 | {{{ |
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16 | #!graphviz |
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17 | digraph G { |
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18 | rankdir = LR; |
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19 | BSC -> BTS0 [ label = "A-bis" dir=both ]; |
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20 | BSC -> BTS1 [ label = "A-bis" dir=both ]; |
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21 | BSC [ shape = square label = "BSC\n172.30.1.10" ]; |
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22 | BTS0 [ shape = square label = "BTS 0\n172.30.1.11" ]; |
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23 | BTS1 [ shape = square label = "BTS 1\n172.30.1.12" ]; |
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24 | } |
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25 | }}} |
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26 | |||
27 | === BTS configuration === |
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28 | |||
29 | There are two OsmoBTS parameters in particular which must be correctly configured: |
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30 | |||
31 | * '''ipa unit-id''' - each BTS must use a unique value |
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32 | * '''oml remote-ip''' - this is the BSC IP address |
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33 | |||
34 | The example configuration that follows is for two BTS both on the GSM900 band. |
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35 | |||
36 | ==== BTS 0 ==== |
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37 | |||
38 | {{{ |
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39 | bts 0 |
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40 | band GSM900 |
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41 | ipa unit-id 1801 0 |
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42 | oml remote-ip 172.30.1.11 |
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43 | rtp jitter-buffer 0 |
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44 | paging lifetime 0 |
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45 | gsmtap-sapi bcch |
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46 | gsmtap-sapi ccch |
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47 | gsmtap-sapi rach |
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48 | gsmtap-sapi agch |
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49 | gsmtap-sapi pch |
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50 | gsmtap-sapi sdcch |
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51 | gsmtap-sapi pacch |
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52 | gsmtap-sapi pdtch |
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53 | gsmtap-sapi sacch |
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54 | fn-advance 20 |
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55 | ms-power-loop -10 |
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56 | timing-advance-loop |
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57 | trx 0 |
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58 | rxgain 12 |
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59 | power 0 |
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60 | trx 1 |
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61 | rxgain 12 |
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62 | power 0 |
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63 | }}} |
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64 | |||
65 | ==== BTS 1 ==== |
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66 | |||
67 | {{{ |
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68 | bts 1 |
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69 | band GSM900 |
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70 | ipa unit-id 1802 0 |
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71 | oml remote-ip 172.30.1.12 |
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72 | rtp jitter-buffer 0 |
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73 | paging lifetime 0 |
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74 | gsmtap-sapi bcch |
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75 | gsmtap-sapi ccch |
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76 | gsmtap-sapi rach |
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77 | gsmtap-sapi agch |
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78 | gsmtap-sapi pch |
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79 | gsmtap-sapi sdcch |
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80 | gsmtap-sapi pacch |
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81 | gsmtap-sapi pdtch |
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82 | gsmtap-sapi sacch |
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83 | fn-advance 20 |
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84 | ms-power-loop -10 |
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85 | timing-advance-loop |
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86 | trx 0 |
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87 | rxgain 12 |
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88 | power 0 |
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89 | trx 1 |
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90 | rxgain 12 |
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91 | power 0 |
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92 | }}} |
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93 | |||
94 | === BSC configuration === |
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95 | |||
96 | There are a number of NITB parameters that you must pay particular attention to: |
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97 | |||
98 | * '''BTS ''n''' |
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99 | * '''band''' - as configured in the BTS |
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100 | * '''base_station_id_code''' - should be unique in location area |
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101 | * '''ip.access unit_id''' - as configured in the BTS |
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102 | * '''trx ''n'' |
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103 | * '''arfcn''' - this must be frequencies that you have a licence for and the channels used must be unique across all TRX and BTS |
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104 | * '''neighbor-list mode automatic''' |
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105 | |||
106 | Of course, there are many other parameters that can be set and which may be important to your installation. For details of all the configuration options please see the [wiki:osmo-nitb_VTY NITB VTY reference]. |
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107 | |||
108 | {{{ |
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109 | ! |
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110 | ! OpenBSC (UNKNOWN) configuration saved from vty |
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111 | !! |
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112 | password foo |
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113 | ! |
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114 | line vty |
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115 | no login |
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116 | ! |
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117 | e1_input |
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118 | e1_line 0 driver ipa |
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119 | e1_line 0 port 0 |
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120 | no e1_line 0 keepalive |
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121 | network |
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122 | network country code 1 |
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123 | mobile network code 1 |
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124 | short name Osmocom |
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125 | long name Osmocom |
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126 | auth policy accept-all |
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127 | location updating reject cause 13 |
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128 | encryption a5 0 |
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129 | neci 1 |
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130 | paging any use tch 0 |
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131 | rrlp mode none |
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132 | mm info 1 |
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133 | handover 1 |
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134 | handover window rxlev averaging 10 |
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135 | handover window rxqual averaging 1 |
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136 | handover window rxlev neighbor averaging 10 |
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137 | handover power budget interval 6 |
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138 | handover power budget hysteresis 3 |
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139 | handover maximum distance 9999 |
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140 | timer t3101 10 |
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141 | timer t3103 0 |
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142 | timer t3105 0 |
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143 | timer t3107 0 |
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144 | timer t3109 4 |
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145 | timer t3111 0 |
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146 | timer t3113 60 |
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147 | timer t3115 0 |
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148 | timer t3117 0 |
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149 | timer t3119 0 |
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150 | timer t3122 10 |
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151 | timer t3141 0 |
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152 | dtx-used 0 |
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153 | subscriber-keep-in-ram 0 |
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154 | bts 0 |
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155 | type sysmobts |
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156 | band GSM900 |
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157 | cell_identity 0 |
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158 | location_area_code 1 |
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159 | base_station_id_code 63 |
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160 | ms max power 15 |
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161 | cell reselection hysteresis 4 |
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162 | rxlev access min 0 |
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163 | periodic location update 30 |
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164 | radio-link-timeout 32 |
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165 | channel allocator ascending |
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166 | rach tx integer 9 |
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167 | rach max transmission 7 |
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168 | channel-descrption attach 1 |
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169 | channel-descrption bs-pa-mfrms 5 |
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170 | channel-descrption bs-ag-blks-res 1 |
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171 | ip.access unit_id 1801 0 |
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172 | oml ip.access stream_id 255 line 0 |
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173 | neighbor-list mode automatic |
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174 | gprs mode none |
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175 | no force-combined-si |
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176 | trx 0 |
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177 | rf_locked 0 |
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178 | arfcn 74 |
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179 | nominal power 23 |
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180 | max_power_red 0 |
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181 | rsl e1 tei 0 |
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182 | timeslot 0 |
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183 | phys_chan_config CCCH+SDCCH4 |
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184 | hopping enabled 0 |
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185 | timeslot 1 |
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186 | phys_chan_config SDCCH8 |
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187 | hopping enabled 0 |
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188 | timeslot 2 |
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189 | phys_chan_config TCH/F |
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190 | hopping enabled 0 |
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191 | timeslot 3 |
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192 | phys_chan_config TCH/F |
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193 | hopping enabled 0 |
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194 | timeslot 4 |
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195 | phys_chan_config TCH/F |
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196 | hopping enabled 0 |
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197 | timeslot 5 |
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198 | phys_chan_config TCH/F |
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199 | hopping enabled 0 |
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200 | timeslot 6 |
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201 | phys_chan_config TCH/F |
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202 | hopping enabled 0 |
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203 | timeslot 7 |
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204 | phys_chan_config TCH/F |
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205 | hopping enabled 0 |
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206 | trx 1 |
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207 | rf_locked 0 |
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208 | arfcn 84 |
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209 | nominal power 23 |
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210 | max_power_red 0 |
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211 | rsl e1 tei 0 |
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212 | timeslot 0 |
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213 | phys_chan_config TCH/F |
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214 | hopping enabled 0 |
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215 | timeslot 1 |
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216 | phys_chan_config TCH/F |
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217 | hopping enabled 0 |
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218 | timeslot 2 |
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219 | phys_chan_config TCH/F |
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220 | hopping enabled 0 |
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221 | timeslot 3 |
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222 | phys_chan_config TCH/F |
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223 | hopping enabled 0 |
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224 | timeslot 4 |
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225 | phys_chan_config TCH/F |
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226 | hopping enabled 0 |
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227 | timeslot 5 |
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228 | phys_chan_config TCH/F |
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229 | hopping enabled 0 |
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230 | timeslot 6 |
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231 | phys_chan_config TCH/F |
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232 | hopping enabled 0 |
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233 | timeslot 7 |
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234 | phys_chan_config TCH/F |
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235 | hopping enabled 0 |
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236 | bts 1 |
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237 | type sysmobts |
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238 | band GSM900 |
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239 | cell_identity 0 |
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240 | location_area_code 1 |
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241 | base_station_id_code 62 |
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242 | ms max power 15 |
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243 | cell reselection hysteresis 4 |
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244 | rxlev access min 0 |
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245 | periodic location update 30 |
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246 | radio-link-timeout 32 |
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247 | channel allocator ascending |
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248 | rach tx integer 9 |
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249 | rach max transmission 7 |
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250 | channel-descrption attach 1 |
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251 | channel-descrption bs-pa-mfrms 5 |
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252 | channel-descrption bs-ag-blks-res 1 |
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253 | ip.access unit_id 1802 0 |
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254 | oml ip.access stream_id 255 line 0 |
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255 | neighbor-list mode automatic |
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256 | gprs mode none |
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257 | no force-combined-si |
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258 | trx 0 |
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259 | rf_locked 0 |
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260 | arfcn 111 |
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261 | nominal power 23 |
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262 | max_power_red 0 |
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263 | rsl e1 tei 0 |
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264 | timeslot 0 |
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265 | phys_chan_config CCCH+SDCCH4 |
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266 | hopping enabled 0 |
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267 | timeslot 1 |
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268 | phys_chan_config SDCCH8 |
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269 | hopping enabled 0 |
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270 | timeslot 2 |
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271 | phys_chan_config TCH/F |
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272 | hopping enabled 0 |
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273 | timeslot 3 |
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274 | phys_chan_config TCH/F |
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275 | hopping enabled 0 |
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276 | timeslot 4 |
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277 | phys_chan_config TCH/F |
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278 | hopping enabled 0 |
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279 | timeslot 5 |
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280 | phys_chan_config TCH/F |
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281 | hopping enabled 0 |
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282 | timeslot 6 |
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283 | phys_chan_config TCH/F |
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284 | hopping enabled 0 |
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285 | timeslot 7 |
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286 | phys_chan_config TCH/F |
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287 | hopping enabled 0 |
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288 | trx 1 |
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289 | rf_locked 0 |
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290 | arfcn 122 |
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291 | nominal power 23 |
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292 | max_power_red 0 |
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293 | rsl e1 tei 0 |
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294 | timeslot 0 |
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295 | phys_chan_config TCH/F |
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296 | hopping enabled 0 |
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297 | timeslot 1 |
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298 | phys_chan_config TCH/F |
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299 | hopping enabled 0 |
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300 | timeslot 2 |
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301 | phys_chan_config TCH/F |
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302 | hopping enabled 0 |
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303 | timeslot 3 |
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304 | phys_chan_config TCH/F |
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305 | hopping enabled 0 |
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306 | timeslot 4 |
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307 | phys_chan_config TCH/F |
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308 | hopping enabled 0 |
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309 | timeslot 5 |
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310 | phys_chan_config TCH/F |
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311 | hopping enabled 0 |
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312 | timeslot 6 |
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313 | phys_chan_config TCH/F |
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314 | hopping enabled 0 |
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315 | timeslot 7 |
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316 | phys_chan_config TCH/F |
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317 | hopping enabled 0 |
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318 | }}} |
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319 | |||
320 | ==== Handover ==== |
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321 | |||
322 | In the above NITB configuration you will see that handover has been enabled and associated parameters configured. These are: |
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323 | |||
324 | * '''handover 1''' |
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325 | * ''Enable in-call handover between multiple BTS.'' |
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326 | |||
327 | * '''handover window rxlev averaging 10''' |
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328 | * ''The receive level of the serving cell should be averaged over 10 SACCH frames.'' |
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329 | |||
330 | * '''handover window rxqual averaging 1''' |
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331 | * ''The receive quality of the serving cell should be averaged over how 1 SACCH frames.'' |
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332 | |||
333 | * '''handover window rxlev neighbor averaging 10''' |
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334 | * ''The Rx Level of a neighbour cell should be averaged over 10 SACCH frames.'' |
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335 | |||
336 | * '''handover power budget interval 6''' |
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337 | * ''Consider performing a power budget (Rx level) handover every 6 SACCH frames.'' |
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338 | |||
339 | * '''handover power budget hysteresis 3''' |
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340 | * ''Set hysteresis (prevents continuous handover back and forth) to 3.'' |
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341 | |||
342 | * '''handover maximum distance 9999''' |
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343 | * ''When the distance from the BTS is greater than 9999 attempt a distance handover.'' |
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344 | |||
345 | These values can be tuned to modify the behaviour of handover. |