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

SLIDE 1

S G s i n t e r f a c e i n O s mo MS C

Philipp Maier <pmaier@sysmocom.de>

SLIDE 2

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

n

d e t a i l s

SLIDE 3

T h e r e i s n

C

S

D
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

r

k .

–

I P

n

l y , N

v
i

c e , N

S

MS

➔

V

i

c e a n d S MS i s p r

v

i d e d v i a I MS

–

S t a n d s f

r

“ I P Mu l t i m e d i a S u b s y s t e m ”

–

V

i

c e p r

v

i e d e d b y V

L

T E ( “ V

i

c e

v

e r L T E ” )

–

S MS p r

v

i d e d b y R C S ( “ R i c h C

m

m u n i c a t i

n

S e r v i c e s ” )

➔

Wh e n I MS i s n

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 .

SLIDE 4

C S F B i s a a n a l t e r n a t i v e t

I

MS

➔

I MS c a n b e c

m

p l e m e n t e d w i t h S G s / C S F B

–

C

n

s e r v a t i v e a p p r

a

c h ,

l

d c

r

e n e t w

r

k c

m

p

n

e n t s m a y r e m a i n i n t

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

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

u

t v i a 2 G / 3 G R A N .

–

n

l y p

s

s i b l e w h e n t h e r e i s 2 G / 3 G c

v

e r a g e a v a i l a b l e

SLIDE 5

T h e b a s i c i d e a

f

C S F B

SLIDE 6

T h e b a s i c i d e a

f

C S F B

SLIDE 7

T h e b a s i c i d e a

f

C S F B

➔

P h

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

r

w a r e d t

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

r

t e d b y t h e V L R / MS C ( 2 G / 2 G ) t

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

n

e d

w

n t

2

G / 2 G R A N f

r

t h e d u r a t i

n
f

t h e c a l l .

➔

MO c a l l s a r e j u s t d

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

n

e v i a 2 G / 3 G . Requires special sigalling between LTE and 2G/3G: SGsAP via SGs interface.

SLIDE 8

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

n

d e t a i l s

SLIDE 9

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

n

n e c t s MME a n d MS C .

➔

V e r y s i m i l a r t

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 .

SLIDE 10

B a s i c f a c t s a b

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

r

t v i a S C T P / I P , p

r

t 2 9 1 1 8 , m s c = s e r v e r

➔

P r

t
c
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

n

l y , w i t h t h e e x c e p t i

n
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

c

i a t i

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

SLIDE 11

MME a n d V L R mu s t c

r

d i n a t e

➔

S u b s c r i b e r C

r

d i n a t i

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

m

a n a g e a n S G s

a

s s

c

i a t i

n

.

➔

T h e S G s

a

s s

c

i a t i

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

n

t

t

h e MME

–

L

c

a t i

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

m

i r r

r

t h e s t a t e .

See also: 3GPP TS 29.118, Chapter 4.2.2 States at the VLR

SLIDE 12

MME a n d V L R mu s t c

r

d i n a t e

➔

A n S G s l

c

a t i

n

u p d a t e b r i n g s t h e F S M i n t

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

r

C S F B a n d S MS b y t h e MS C )

➔

A 2 G l

c

a t i

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

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

n

s a s a n

r

m a l 2 G s u b s c r i b e r )

➔

A n y k i n d

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

c

i a t i

n

. ( D e t a c h f r

m

E P S i s p

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

n

a s a n

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

SLIDE 13

MME a n d V L R mu s t c

r

d i n a t e

➔

T h e F S M i s r e s e t t

N

U L L

n

a n y u n e x p e c t e d s i t u a t i

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

f
s

m

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 (

p

t i

n

a l f e a t u r e , n

t

i m p l e m e n t e d i n

s

m

m

s c )

See also: 3GPP TS 29.118, Chapter 4.2.2 States at the VLR

SLIDE 14

P r

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

r

n

n
E

P S s e r v i c e s p r

c

e d u r e

➔

L

c

a t i

n

u p d a t e f

r

n

n
E

P S s e r v i c e s p r

c

e d u r e

➔

N

n
E

P S a l e r t p r

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

m

E P S s e r v i c e s

➔

E x p l i c i t I MS I d e t a c h f r

m

n

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

m

n

n
E

P S s e r v i c e s

➔

V L R f a i l u r e p r

c

e d u r e

➔

MME f a i l u r e p r

c

e d u r e

➔

H S S f a i l u r e

➔

MM i n f

r

m a t i

n

p r

c

e d u r e

➔

P r

c

e d u r e f

r

t u n n e l l i n g

f

N A S m e s s a g e s

➔

S e r v i c e r e q u e s t p r

c

e d u r e

➔

S e r v i c e a b

r

t p r

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

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

n

p r

c

e d u r e

➔

P r

c

e d u r e f

r

MO C S F B i n d i c a t i

n

➔

L

c

a t i

n

u d a t e

➔

MO / MT S MS

➔

MT / MO C S F B c a l l

➔

I MS I d e t a c h

➔

R e s e t ( V L R f a i l u r e / r e s t a r t )

SLIDE 15

S G s b a s e d L

c

a t i

n

U p d a t e

SLIDE 16

S G s b a s e d L

c

a t i

n

U p d a t e

SLIDE 17

S G s b a s e d L

c

a t i

n

U p d a t e

SLIDE 18

S G s b a s e d L

c

a t i

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.

SLIDE 19

MO S MS v i a S G s

SLIDE 20

MT S MS v i a S G s

SLIDE 21

S G s b a s e d MT C a l l

The Sgs-associaction remains In state SGs-ASSOCIATED througout the whole voice call. RAT change is taking place.

SLIDE 22

S G s b a s e d MO C a l l

No MME/VLR communication, technically works like a regular MO call on the 2G side.

SLIDE 23

D e t a c h – Y

u

c a n g

y
u

r

w

n w a y . . .

Detach EPS Detach IMSI Detach GONE SGs-NULL Subscriber continues to live on as a normal 2G/3G subscriber Subscriber is purged from the VLR (Detached)

SLIDE 24

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

n

d e t a i l s

SLIDE 25

A t w

t

e r r i t

r

y i mp l e me n t a t i

n

➔

T r a n s m i t / R e c e i v e

f

i n c

m

i n g S G s m e s s a g e s , h a n d l i n g

f

n e t w

r

k s

c

k e t a n d s t a t e .

➔

Me s s a g e p a r s i n g / g e n e r a t i

n

, c h e c k i n g

f

m e s s a g e c

n

t e n t s .

➔

E x e c u t i

n
f

p r

c

e d u r e s / a c t i

n

s ( e . g . l

c

a t i

n

u p d a t e , p a g i n g , S MS . . . )

➔

C

m

m u n i c a t i

n

w i t h V L R , c r e a t e / d e t a c h s u b s c r i b e r s , r e q u e s t s u b s c r i b e r c

n

t e x t s e t c . MSC VLR

➔

S G s a s s

c

i a t i

n

h a n d l i n g , d e c i s i

n

m a k i n g b a s e d

n

S G s s t a t e .

➔

C

m

m u n i c a t i

n

w i t h H L R , e x e c u t i

n
f

L U p r

c

e d u r e

➔

S u b s c r i b e r m a n a g e m e n t ( r e f c

u

n t i n g , S G s s t a t e , L U s t a t e e t c . )

➔

C

m

m u n i c a t i

n

w i t h MS C , s

t

h a t t h e MS C p a r t c a n t a k e a p p r

p

i a t e a c t i

n

s

SLIDE 26

I mp l e me n t a t i

n

i n

s

mo

ms

c

➔

i s

l

a t e V L R r e l a t e d p a r t s f r

m

MS C r e l a t e d p a r t s . ( c u r r e n t p r i n c i p l e )

➔

“ Wo r k ” i s d

n

e

n

t h e MS C s i d e , s u b s c r i b e r h a n d l i n g . i s d

n

e

n

t h e V L R s i d e .

➔

D

n
t

m e s s w i t h t h e F S M d i r e c t l y , u s e a n A P I t

p

e r f

r

m a c t i

n

s .

➔

A c t i

n

s m a y l e a d t

s

t a t e c h a n g e s

f

t h e S G s a s s

c

i a t i

n

.

SLIDE 27

S G s i n t e r f a c e i n O s mo MS C

Philipp Maier <pmaier@sysmocom.de>