import message sequence charts (ladder diagrams) for RUA/RANAP/NAS
diff --git a/doc/hnb_ps_pdp_act.msc b/doc/hnb_ps_pdp_act.msc
new file mode 100644
index 0000000..2f2f3cf
--- /dev/null
+++ b/doc/hnb_ps_pdp_act.msc
@@ -0,0 +1,25 @@
+msc {
+ hscale="3", wordwraparcs="1";
+ ue,hnb,hnbgw,sgsn,ggsn;
+
+ ue box hnb [ label = "Radio Channel Establishment, possibly already done by IMSI ATTACH / RAU" ];
+ ue => hnb [ label = "RRC (SM PDP CTX ACT REQ)" ];
+ hnb => hnbgw [ label = "RUA DT (RANAP DirectTransfer (SM PDP CTX ACT REQ))" ];
+ hnbgw => sgsn [ label = "SCCP DT1 (RANAP DirectTransfer (SM PDP CTX ACT REQ))" ];
+
+ sgsn => ggsn [ label = "GTP-C PDP CTX ACT REQ" ];
+ ggsn >> sgsn [ label = "GTP-C PDP CTX ACT ACK (IP+TEI of GGSN)" ];
+
+ sgsn => hnbgw [ label = "SCCP DT1 (RANAP Activate RAB Req (IP+TEI of GGSN)" ];
+ hnbgw => hnb [ label = "RUA DT (RANAP Activate RAB Req (IP+TEI of GGSN)" ];
+ hnb box ue [ label = "RAB Establishment" ];
+ hnb >> hnbgw [ label = "RUA DT (RANAP Activate RAB Resp (IP + TEI of HNB)" ];
+ hnbgw >> sgsn [ label = "SCCP DT1 (RANAP Activate RAB Resp (IP + TEI of HNB)" ];
+
+ sgsn => ggsn [ label = "GTP-C PDP CTX MOD REQ (IP + TEI of HNB)" ];
+ ggsn >> sgsn [ label = "GTP-C PDP CTX MOD RESP" ];
+
+ sgsn >> hnbgw [ label = "SCCP DT1 (RANAP DirectTransfer (SM PDP CTX ACT ACK))" ];
+ hnbgw >> hnb [ label = "RUA DT (RANAP DirectTransfer (SM PDP CTX ACT ACK))" ];
+ hnb >> ue [ label = "RRC (SM PDP CTX ACT ACK))" ];
+}