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Diffstat (limited to 'doc/manuals/chapters/handover.adoc')
-rw-r--r-- | doc/manuals/chapters/handover.adoc | 103 |
1 files changed, 102 insertions, 1 deletions
diff --git a/doc/manuals/chapters/handover.adoc b/doc/manuals/chapters/handover.adoc index 297eafc1f..c75b03c40 100644 --- a/doc/manuals/chapters/handover.adoc +++ b/doc/manuals/chapters/handover.adoc @@ -19,7 +19,8 @@ orchestrating completely separate RAN stacks. OsmoBSC currently supports handover within one BSS and between separate BSS. Whether inter-MSC is supported depends on the MSC implementation (to the BSC, inter-MSC handover looks identical to inter-BSC handover). Inter-RAT handover -is currently not implemented. +is currently not implemented. However, you may still advertise 3G and 4G neighbor cells +in order to facilitate cell/RAT re-selection to those neighbors. At the time of writing, OsmoMSC's inter-BSC handover support is not complete yet, so OsmoBSC can perform handover between separate BSS only in conjunction @@ -575,3 +576,103 @@ OsmoBSC: - Algorithm 1 has no `min rxlev` setting. - Algorithm 1 does not actually use any information besides the Measurement Reports, and hence can trivially treat all neighbor cells identically. + +=== Advertising 3G/4G neighbors + +Despite osmo-bsc not supporting inter-RAT hand-over at this point, it +still makes sense to advertise neighbor cells of other network +technologies like UMTS/UTRAN (3G) and LTE/EUTRAN (4G). This will help +phones with idle-mode re-selection of the best available radio access +technology (RAT). + +For more information on the inter-RAT cell re-selection algorithm and its +parameters, see 3GPP TS 45.008 - particularly Section 6.6.4 describing +measurements on cells of other (non-GSM) RATs. + +Such neighbors are advertised as part of the SI2quater (System +Information Type 2quater). + +==== UMTS/UTRAN/3G neighbors + +In order to advertise a 3G neighbor cell you have to specify the +following properties: + +* the UARFCN (UTRAN Absolute Radio Channel Number) on which the cell + broadcasts +* the Scrambling Code of the cell +* whether or not the cell uses diversity + + +In the following example, we're configuring a 3G neighbor cell on UARFCN +1234 using the scrambling code 511 with no diversity: + +---- +network + bts 0 + si2quater neighbor-list add uarfcn 1234 511 0 +---- + +3G neighbor cells can be removed using the same command, just replacing +`add` with `del`. + +==== LTE/EUTRAN/4G neighbors + +In order to advertise a 4G neighbor cell you have to specify the +following properties: + +* EARFCN (EUTRAN Absolute Radio Channel Number) on which the cell + broadcasts +* Reselection thresholds towards E-UTRAN cells: +[width="30%"] +|==== +| 0 | 0 dB +| 1 | 2 dB +| 2 | 4 dB +| 3 | 6 dB +| ... | ... +| 31 | 62 dB +|===== +* Priority of E-UTRAN frequency: 0 = lowest priority, ..., 7 = highest priority +* QRXLEVMIN parameter: Minimum required RX level in the UTRAN FDD cell + (dBm), see 3GPP TS 25.304. +[width="30%"] +|==== +| 0 | -140 dBm +| 1 | -138 dBm +| 2 | -136 dBm +| ... | ... +| 31 | -78 dBm +|==== +* Measurement bandwidth in MHz, see 3GPP TS 44.018 and 3GPP TS 44.060. + This field specifies the minimum value of the channel bandwidth of all + valid E-UTRAN cells on the specified EARFCN. It is defined by the + parameter Transmission Bandwidth Configuration, N RB (see 3GPP TS + 36.104). The values indicate the number of resource blocks over which + the mobile station could measure if the mobile station does not + support wideband RSRQ measurements (see 3GPP TS 24.008). A mobile + station supporting wideband RSRQ measurements shall measure over the + indicated number of resource blocks. The field is coded according to + the following table: +[width="30%"] +|==== +| 0 | N_RB = 6 +| 1 | N_RB = 15 +| 2 | N_RB = 25 +| 3 | N_RB = 50 +| 4 | N_RB = 75 +| 5 | N_RB = 100 +|==== + +In the following example we're configuring a 4G neighbor on EARFCN 2342 +with a higher reselection threshold of 40dB, a lower reselection +threshold of 20dB, priority 5, QRXLEVMIN of -140 dBm and a measurement +bandwidth of 100 resource blocks: + +---- +network + bts 0 + si2quater neighbor-list add earfcn 2342 thresh-hi 20 thresh-lo 10 prio 5 qrxlv 0 meas 5 +---- + +4G neighbor cells can be removed using the same command, just replacing +`add` with `del`. |