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Diffstat (limited to 'doc/sequence_charts/inter_msc_ho.msc')
| -rw-r--r-- | doc/sequence_charts/inter_msc_ho.msc | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/doc/sequence_charts/inter_msc_ho.msc b/doc/sequence_charts/inter_msc_ho.msc new file mode 100644 index 000000000..f7572d1b5 --- /dev/null +++ b/doc/sequence_charts/inter_msc_ho.msc @@ -0,0 +1,82 @@ +msc { + hscale=2; + bsca [label="BSC-A"], ai[label="MSC-I (at MSC-A)"], a[label="MSC-A"], bt[label="MSC-T (at MSC-B)"], bi[label="MSC-I (at MSC-B)"], bscb[label="BSC-B"], + ct[label="MSC-T (at MSC-C)"], bscc[label="BSC-C"]; + + ai note bt [label="'MSC-A,I,T' are explained in 3GPP TS 49.008 '4.3 Roles of MSC-A, MSC-I and MSC-T'"]; + ai note ai [label="I = Internal; the MSC that does BSSMAP to the BSC (may change to a remote MSC-B after HO)"]; + a note a [label="A = first; the MSC that has MM control (never changes)"]; + bt note bi [label="B = second; the MSC that acts as BSS relay for MSC-A"]; + bt note bt [label="T = transitory; the MSC that a handover is going towards (may be MSC-A for inter-BSC HO, may be a remote MSC-B)"]; + + bsca => ai [label="BSSMAP Handover Required"]; + ai -> a [label="BSSMAP Handover Required"]; + + a rbox a [label="MSC-A routes all MSC-T messages to remote MSC-B."]; + + a => bt [label="MAP Prepare Handover"]; + a note bt [label="in Osmocom, MAP messages are actually sent as GSUP, to the HLR"]; + + bt rbox bt [label="MSC-B routes all MSC-A type messages back to MSC-A."]; + bt rbox bt [label="MSC-B generates a Handover MSISDN"]; + + bt => bscb [label="BSSMAP Handover Request"]; + bt <= bscb [label="BSSMAP Handover Request ACK"]; + a <= bt [label="MAP Prepare Handover Response"]; + + a => bt [label="establish SIP call to Handover MSISDN via external MNCC"]; + + ai <- a [label="BSSMAP Handover Command"]; + bsca <= ai [label="BSSMAP Handover Command"]; + + --- [label="MS sends RACH to new cell"]; + + bt <= bscb [label="BSSMAP Handover Detected"]; + a <= bt [label="MAP Access Signaling Request"]; + + bt <= bscb [label="BSSMAP Handover Complete"]; + a <= bt [label="MAP Send End Signal"]; + bt rbox bt [label="MSC-B drops the generated Handover MSISDN"]; + + a abox a [label="MSC-A accepts the new MSC-B and BSC"]; + ai note bt [label="previous MSC-I (A) gets dropped, MSC-T (B) becomes the new MSC-I"]; + ai rbox a [label="MSC-A performs all MSC-I tasks via MAP at remote MSC-B's MSC-I."]; + bt abox bi [label="MSC-I"]; + ai abox ai [label="discard"]; + bsca <= ai [label="BSSMAP Clear Command"]; + + ...; + ...; + + --- [label="Another inter-MSC handover"]; + a note bi [label="MSC-A remains in charge"]; + + bscb => bi [label="BSSMAP Handover Required"]; + bi => a [label="BSSMAP Handover Required"]; + + a rbox a [label="MSC-A routes all MSC-T messages to remote MSC-C."]; + + a => ct [label="MAP Prepare Handover"]; + ct rbox ct [label="MSC-C routes all MSC-A type messages back to MSC-A."]; + ct => bscc [label="BSSMAP Handover Request"]; + ct <= bscc [label="BSSMAP Handover Request ACK"]; + a <= ct [label="MAP Prepare Handover Response"]; + a => bi [label="MAP Prepare Handover Response"]; + bscb <= bi [label="BSSMAP Handover Command"]; + + --- [label="MS sends RACH to new cell"]; + + ct <= bscc [label="BSSMAP Handover Detected"]; + a <= ct [label="MAP Access Signaling Request"]; + + ct <= bscc [label="BSSMAP Handover Complete"]; + a <= ct [label="MAP Send End Signal"]; + + a abox a [label="MSC-A accepts the new MSC-C and BSC"]; + bi note ct [label="previous MSC-I (B) gets dropped, MSC-T (B) becomes the new MSC-I"]; + ai rbox a [label="MSC-A performs all MSC-I tasks via MAP at remote MSC-C's MSC-I."]; + ct abox ct [label="MSC-I"]; + bi abox bi [label="discard"]; + bscb <= bi [label="BSSMAP Clear Command"]; + +} |