S G s i n t e r f a c e i n O s mo MS C Philipp - PowerPoint PPT Presentation

S G s i n t e r f a c e i n O s mo MS C Philipp Maier <pmaier@sysmocom.de> 28/05/19 (c) 2019 sysmocom GmbH 1

A g e n d a C i r c u i t s w i t c h e d f a l l b a c k ➔ S G s i n t e r f a c e ➔ I m p l e m e n t a t i o n d e t a i l s ➔ 28/05/19 (c) 2019 sysmocom GmbH 2

T h e r e i s n o C S - D o ma i n i n L T E ➔ L T E i s a p u r e p a c k e t s w i t c h e d n e t w o r k . – I P o n l y , N o v o i c e , N o S MS V o i c e a n d S MS i s p r o v i d e d v i a I MS ➔ – S t a n d s f o r “ I P Mu l t i m e d i a S u b s y s t e m ” – V o i c e p r o v i e d e d b y V o L T E ( “ V o i c e o v e r L T E ” ) – S MS p r o v i d e d b y R C S ( “ R i c h C o m m u n i c a t i o n S e r v i c e s ” ) ➔ Wh e n I MS i s n o t a v a i l a b l e , C i r c u i t s w i t c h e d f a l l b a c k ( C S F B ) c a n b e u s e d . 28/05/19 (c) 2019 sysmocom GmbH 3

C S F B i s a a n a l t e r n a t i v e t o I MS ➔ I MS c a n b e c o m p l e m e n t e d w i t h S G s / C S F B – C o n s e r v a t i v e a p p r o a c h , o l d c o r e n e t w o r k c o m p o n e n t s m a y r e m a i n i n t o s e r v i c e S MS d e l i v e r y i s c a r r i e d o u t v i a MS C / V L R ( 2 G / 3 G ) ➔ C a l l s a r e c a r r i e d o u t v i a 2 G / 3 G R A N . ➔ – o n l y p o s s i b l e w h e n t h e r e i s 2 G / 3 G c o v e r a g e a v a i l a b l e 28/05/19 (c) 2019 sysmocom GmbH 4

T h e b a s i c i d e a o f C S F B 28/05/19 (c) 2019 sysmocom GmbH 5

T h e b a s i c i d e a o f C S F B 28/05/19 (c) 2019 sysmocom GmbH 6

T h e b a s i c i d e a o f C S F B P h o n e i s r e g i s t e r e d a t MME / H S S ( 4 G ) a n d MS C / V L R ( 2 G / 3 G ) a t t h e s a m e t i m e ➔ ➔ S MS m e s s a g e s t h a t a r r i v e a t t h e MS C / V L R ( 2 G / 2 G ) a r e f o r w a r e d t o t h e MME ( 4 G ) a n d v i c e v e r s a ➔ MT c a l l s a r e r e p o r t e d b y t h e V L R / MS C ( 2 G / 2 G ) t o t h e MME ( 4 G ) , w h i c h t h e n s e n d s t h e Mo b i l e p h o n e d o w n t o 2 G / 2 G R A N f o r t h e d u r a t i o n o f t h e c a l l . MO c a l l s a r e j u s t d o n e l i k e a r e g u l a r c a l l b y t h e Mo b i l e p h o n e v i a 2 G / 3 G . ➔ Requires special sigalling between LTE and 2G/3G: SGsAP via SGs interface. 28/05/19 (c) 2019 sysmocom GmbH 7

A g e n d a C i r c u i t s w i t c h e d f a l l b a c k ➔ S G s i n t e r f a c e ➔ I m p l e m e n t a t i o n d e t a i l s ➔ 28/05/19 (c) 2019 sysmocom GmbH 8

A d d a b r i d g e b e t w e e n L T E a n d 2 G / 3 G T h e S G s i n t e r f a c e c o n n e c t s MME a n d MS C . ➔ V e r y s i m i l a r t o a t h i r d R A N b e s i d e s A a n d I u C S , b u t w i t h s u b t i l e d i fg e r e n c e s . ➔ 28/05/19 (c) 2019 sysmocom GmbH 9

B a s i c f a c t s a b o u t t h e S G s i n t e r f a c e S p e c i fj e d i n 3 G P P T S 2 9 . 1 1 8 ➔ T r a n s p o r t v i a S C T P / I P , p o r t 2 9 1 1 8 , m s c = s e r v e r ➔ P r o t o c o l i s c a l l e d " S G s A P " ➔ T L V m e s s a g e s ➔ S i g n a l i n g o n l y , w i t h t h e e x c e p t i o n o f S MS ( U n i t d a t a / N A S ) ➔ ➔ R e q u i r e s a n " S G s - A s s o c i a t i o n ” i n t h e V L R ( a n d MME ) p e r s u b s c r i b e r 28/05/19 (c) 2019 sysmocom GmbH 10

MME a n d V L R mu s t c o - o r d i n a t e S u b s c r i b e r C o o r d i n a t i o n b e t w e e n ➔ MME a n d V L R i s n e e d e d . A t h r e e - s t a t e F S M i s u s e d t o m a n a g e a n S G s - a s s o c i a t i o n . T h e S G s - a s s o c i a t i o n m a i n t a i n s t h e ➔ s u b s c r i b e r s t a t e i n r e l a t i o n t o t h e MME – L o c a t i o n u p d a t e – S u b s c r i b e r a v a i l a b i l i t y ( C S F B , S MS v i a S G s ) ➔ A s i m i l a r F S M e x i s t s i n s i d e t h e MME t o m i r r o r t h e s t a t e . See also: 3GPP TS 29.118, Chapter 4.2.2 States at the VLR 28/05/19 (c) 2019 sysmocom GmbH 11

MME a n d V L R mu s t c o - o r d i n a t e A n S G s l o c a t i o n u p d a t e b r i n g s t h e ➔ F S M i n t o t h e S G s - A S S O C I A T E D s t a t e . ( S u b s c r i b e r i s a v a i l a b l e f o r C S F B a n d S MS b y t h e MS C ) A 2 G l o c a t i o n u p d a t e ( A - I n t e r f a c e ) ➔ s e n d s t h e F S M i n t o t h e S G s - N U L L s t a t e . ( S u b s c r i b e r f u n c t i o n s a s a n o r m a l 2 G s u b s c r i b e r ) ➔ A n y k i n d o f d e t a c h i n v a l i d a t e s t h e S G s a s s o c i a t i o n . ( D e t a c h f r o m E P S i s p o s s i b l e , s u b s c r i b e r t h e n l i v e s o n a s a n o r m a l 2 G s u b s c r i b e r ) See also: 3GPP TS 29.118, Chapter 4.2.2 States at the VLR 28/05/19 (c) 2019 sysmocom GmbH 12

MME a n d V L R mu s t c o - o r d i n a t e ➔ T h e F S M i s r e s e t t o N U L L o n a n y u n e x p e c t e d s i t u a t i o n : – V L R f a i l u r e / r e s e t ( e . g . r e s t a r t o f o s m o - h l r ) – MME f a i l u r e / r e s e t – P a g i n g f a i l u r e – A l e r t f a i l u r e ( o p t i o n a l f e a t u r e , n o t i m p l e m e n t e d i n o s m o - m s c ) See also: 3GPP TS 29.118, Chapter 4.2.2 States at the VLR 28/05/19 (c) 2019 sysmocom GmbH 13

P r o c e d u r e s a t t h e S G s i n t e r f a c e P a g i n g f o r n o n - E P S s e r v i c e s p r o c e d u r e ➔ L o c a t i o n u p d a t e f o r n o n - E P S s e r v i c e s p r o c e d u r e ➔ N o n - E P S a l e r t p r o c e d u r e ➔ ➔ E x p l i c i t I MS I d e t a c h f r o m E P S s e r v i c e s ➔ L o c a t i o n u d a t e E x p l i c i t I MS I d e t a c h f r o m n o n - E P S s e r v i c e s ➔ I m p l i c i t I MS I d e t a c h f r o m n o n - E P S s e r v i c e s ➔ ➔ MO / MT S MS ➔ V L R f a i l u r e p r o c e d u r e MME f a i l u r e p r o c e d u r e ➔ MT / MO C S F B c a l l ➔ H S S f a i l u r e ➔ I MS I d e t a c h ➔ ➔ MM i n f o r m a t i o n p r o c e d u r e P r o c e d u r e f o r t u n n e l l i n g o f N A S m e s s a g e s ➔ R e s e t ( V L R f a i l u r e / r e s t a r t ) ➔ S e r v i c e r e q u e s t p r o c e d u r e ➔ ➔ S e r v i c e a b o r t p r o c e d u r e ➔ I m p l i c i t I MS I d e t a c h f r o m E P S s e r v i c e s U E f a l l b a c k s u p e r v i s i o n p r o c e d u r e ➔ P r o c e d u r e f o r MO C S F B i n d i c a t i o n ➔ 28/05/19 (c) 2019 sysmocom GmbH 14

S G s b a s e d L o c a t i o n U p d a t e 28/05/19 (c) 2019 sysmocom GmbH 15

S G s b a s e d L o c a t i o n U p d a t e 28/05/19 (c) 2019 sysmocom GmbH 16

S G s b a s e d L o c a t i o n U p d a t e 28/05/19 (c) 2019 sysmocom GmbH 17

S G s b a s e d L o c a t i o n U p d a t e Now the SGs-associaction is In state SGs-ASSOCIATED and the network is ready to perform CSFB calls / SMS. 28/05/19 (c) 2019 sysmocom GmbH 18