add slides for upcoming Korean public domain + FOSS conference

1 files changed, 92 insertions, 0 deletions

diff --git a/2019/osmodevcon2019-osmocom_and_lte/osmodevcon2019-osmocom_and_lte.adoc b/2019/osmodevcon2019-osmocom_and_lte/osmodevcon2019-osmocom_and_lte.adoc
new file mode 100644
index 0000000..bd71b2f
--- /dev/null
+++ b/2019/osmodevcon2019-osmocom_and_lte/osmodevcon2019-osmocom_and_lte.adoc
@@ -0,0 +1,92 @@
+Osmocom and LTE
+===============
+:author:	Harald Welte <laforge@gnumonks.org>
+:copyright:	2019 by Harald Welte (License: CC-BY-SA)
+:backend:	slidy
+:max-width:	45em
+
+
+== Osmocom and LTE
+
+* most of Osmocom CNI is written by paid developers these days
+* developments mostly determined by customer requirements
+* sysmocom isn't facing any significnat LTE requirements for years
+* Result: No _native_ LTE support in any Osmocom components
+* However: we do have small LTE related bits
+** SI2quater for broadcasting eUTRAN neighbors over GSM
+** SGs interface for 2G/3G side of CSFB and for SMS-over-SGs
+
+== Irrespective of Osmocom...
+
+What do we need to run a combined 2G/4G network?
+
+1. shared subscriber database (HLR + HSS)
+2. advertisement of respective neighbor cells
+3. shared PS tunnel endpoint (GGSN + P-GW)
+
+optionally:
+
+* SGs interface in MME and MSC for CSGB + SMS-over-SGs
+* Inter-RAT PS handover
+* SRVCC (Single Radio Voice Call Continuity)
+
+
+== Shared Subscriber Database
+
+* Required mainly for Authentication
+* poor man's hack: Simply install same IMSI/Key material in both HLR and HSS
+** will result in auth re-sync on every authentication due to non-synchronized SEQ/SQN of UMTS AKA
+* proper solution:
+** Single HLR with both GSUP and DIAMETER, or
+** DIAMETER-to-GSUP translator (to make LTE use OsmoHLR), or
+** GSUP-to-DIAMETER translator (to make OsmoMSC/SGSN use HSS)
+
+== Advertisement of neighbor cells
+
+* GSM must advertise eUTRAN neighbors
+** we have SI2quater support in osmo-bts
+** TEMS phones show proper/valid decode
+* LTE must advertise GSM neighbors
+** no "OML" for S1-AP
+** configuration mechanism is vendor-proprietary
+
+== Shared PS tunnel endpoint
+
+* if the MS/eUE moves from GPRS to LTE, it wants to keep PDP/PDN contexts
+* solution: implementing P-GW and GGSN functionality in one element
+** ergw might be able to do that (untested, complex)
+** OsmoGGSN doesn't speak GTPv2C (required for P-GW)
+** nextepc P-GW doesn't speak GTPv1C (required for GGSN)
+
+Solution:
+
+* play with ergw, or
+* adopt nextepc GTPv2C code generator to use msgb/libosmo* and add GTPv2C to OsmoGGSN
+
+== SGs interface
+
+* Osmocom already implements full SGs interface
+* Interaction with MME on LTE side needs only interop testing
+
+
+== Inter-RAT PS handover
+
+* inter-RAT HO offers seamless migration between GERAN + eUTRAN
+* uses S3 interface between MME and SGSN (GTPv2C based)
+* uses S4 interface between S-GW and SGSN (GTPv2C based)
+* tbh, I don't know the details here.
+* any help appreciated
+* https://www.tech-invite.com/3m23/toc/tinv-3gpp-23-401_zh.html
+* probably a long way for Osmocom to support it, given that we don't really do any inter-SGSN HO even inside a single RAT.
+
+== Conclusions
+
+The logical steps to improve our LTE interworking are:
+
+1. split HLR/HSS and split GGSN/P-GW (today)
+2. GSUP-to-DIAMETER translator for shared HLR/HSS
+3. shared GGSN/P-GW for 
+
+== EOF
+
+End of File