当前位置：文档之家› Concepts of 3GPP WCDMA

Concepts of 3GPP WCDMA

S l i d e:1

RFCD 202: Introduction to W-CDMA

Th i s p a p e r e x am i n e s t h e c o r e c on c ep t s o f o n e o p e r a t i n g mode o f t h e I M T-2000 wo r l d w i d e s y s t e m:3GPP WCD M A. Th i s s y s t em i s b a s e d o n t h e WCD M A s y s t em d e v e l op ed i n J a p a n a n d Eu r op e. Wh i l e t h i s s t a n d a r d i s a p a r t o f t h e

h a rmon i z e d wo r l d wid e s t a nd a r d,i t w i l l c o n t i n u e t o b e d e v e l op ed b y t h e3GPP s t a nd a r d s b o dy t h a t o r i g i n a l l y d e v e l op ed

i t.T h i s p a p e r c ov e r s t h e s t a nd a r d a s f o u nd i n t h e Re l e a s e99v e r s i on c o mp l e t e d i n De c embe r1999.A n umbe r o f

f e a t u r e s o f t h e 3GPP s y s t e m h ave b e e n om i t t e d i n t h e R e l e a s e99s t a n d a r d i n o r d e r t o mee t t h e t ime s c h e du l e.T h e s e

om i t t e d f e a t u r e s,a s we l l a s n ew s e r v i c e s,w i l l b e a d d e d i n a s e c ond r e l e a s e o f t h e s t a n d a r d t o b e c omp l e t e d a t t h e e n d o f 2000.

The p h y s i c a l a s p e c t s o f t h e a i r i n t e r f a c e a r e e x a mined a s we l l a s e n o ugh o f t h e u p p e r p r o t o c o l l a y e r s r e q u i r e d t o g a i n a g en e r a l u n d e r s t a n d i n g o f t h e s y s t e m’s o p e r a t i n g p r i n c i p l e s.T h i s p a p e r a s s u mes t h a t t h e r e a d e r h a s a b a s i c

und e r s t a n d i n g o f t h e p r i n c i p l e s o f d i r e c t s e q u e n c e,s p r e a d s p e c t r um c ommun i c a t i on s.

No t e s:

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S l i d e:2

Benefits of 3GPP WCDMA

Higher Capacity -about 2X IS-95, 7X GSM

Ability to Send up to 384 kbps High Speed Data while Moving

(Internet, video, multimedia, etc.)

Up to 2 Mbps Throughput for Fixed Applications

5 MHz Bandwidth is more Immune to Fading

No Accurate Base Station Synchronization Needed

Support for Hand-off To and From GSM

The 3GPP s y s t em i s s e e n a s t h e n ex t g e n e r a t i on r e p l a c emen t f o r PDC i n J a p a n a n d f o r GSM i n many p a r t s o f t h e wo r l d. 3GPP W C D M A o f f e r s mu ch g r e a t e r c a p a c i t y f o r v o i c e r e l a t i v e t o e i t h e r PDC o r GSM.I n a dd i t i o n,i t s u ppo r t s p a ck e t

d a t a a t a l l o f t h

e r a t e s r e q u i r e d t o mee t t h e IMT-2000 g o a l s.T h i s wi l l a l l ow many n e x t g e n e r a t i o n a pp l i c a t i o n s t o c ome t o t h e ma rk e t s c u r r e n t l y s e r v e d b y GSM and PDC.One u n i q u e

f e a t u r e o f 3GPP WCD M A i s t h a t i t r e q u i r e s n o s p e c i a l s y n ch r on i z a t i on b e t ween c e l l s. Mo s t o t h e r d i r e c t s p r e a d CDM A s y s t ems r e qu i r e s y n ch r on i z a t i on t o o p e r a t e(u s u a l l y

r e l y i n g o n GSP s a t e l l i t e t imi n g i n f o rma t i on t o s yn ch r o n i z e e a c h c e l l i n t h e s y s t em). 3GPP’s u n s y n ch r o n i z e d n a t u r e make s p l a c i n g b a s e s t a t i o n s i n u n d e r g r o und s u bway s,i n s i d e bu i l d i n g s,a n d i n t u n n e l s mu ch s i mp l e r.To a i d i n t h e

t r a n s i t i on f r o m GSM,t h e3GPP s y s t em p r o v i d e s f o r h ando f f s b e t ween GS M a nd 3GPP. Thu s,d u a l mod e p h on e s w i l l

a l l ow u s e r s t o f r e e l y r o am

b e twee n t h e l a r g e a r e a s

c o v e r e

d by GSM and n ew 3GPP c ov

e r a g e a r e a s.

No t e s:

S l i d e:3

3GPP Frame Structure

Physical Channels Have a Two Layer Structure:

?Radio frame: 10 ms frame consisting of 15 timeslots

?Timeslot: 667 usec slot consisting of a number of Symbols

Symbols are Defined as:

?One Symbol Consists of a Number of Chips .

?The Number of Chips per Coded Symbol is Equal to the Spread Factor of the Physical

Channel

?Chip is a Bit at the Final Spreading Rate of 3.84 Mchips/s

The f r ame s t r u c t u r e f o r 3GPP i s b a s e d o n t h e c on c ep t o f S upe r f r a mes, wh i c h c on s i s t o f72,10 ms r a d i o f r ame s.Each

r a d i o f r ame i s f u r t h e r b r o k e n d o wn i n t o15,667u s e c t ime s l o t s.E a c h t i mes l o t i s c ompo s e d o f a n u mbe r o f s ymbo l s

wh i c h v a r i e s a c c o r d i n g t o t h e t y p e o f s e r v i c e u s e d. A s ymbol c o n s i s t s o f a v a r i a b l e n umb e r o f c h i p s.The n u mbe r o f

c h i p s p e r s ymbo l i s e qu a l t o t h e s p r e a

d i n g f a c t o r f o r t h a t c h a n n

e l.F o r e x amp l e,a l ow r a t e s e r v i c e h a s256c h i p s p e r

s ymbol wh i c h me a n s t h a t t h e s p r e a d i n g f a c t o r i s256t ime s.A ch i p,i n d i r e c t s e q u en c e,s p r e a d s p e c t r u m s y s t em i s

d e f i n e d a s t h e b i t p e r i o d a t t h e f i n a l s p r e a d i n g r a t e.F o r t h e3GPP s y s t em,t h e f i n a l s p r e a d i n g r a t e i s f i x e d t o3,840,000 c h i p s p e r s e c o nd. Thu s a c h i p f o r t h e3GPP s y s t em h a s a p e r i od o f.26042 mic r o s e c onds.

No t e s:

S l i d e:4

3GPP Timing Options

The 3GPP System has Two Timing Modes:

?Asynchronous Operation -Original Mode

?GPS Synchronized -Added after Harmonization

Asynchronous Mode:

?Eliminates need for GPS Satellite Receivers

?Allows Operation in Tunnels, Buildings, and Subways Where Satellite Reception is Difficult

?Requires Greater Search Time, More Difficult Handoffs

GPS Synchronized Mode:

?Simpler, Faster Searching to Ease Soft Handoffs

?Requires Base Station to Receive GPS Satellite Signals

As men t i o n e d e a r l i e r,t h e3GPP s y s t em o p e r a t e s i n a n u n s y n ch r o n i z e d mod e. However,a f t e r g l o b a l h a rmon i z a t i o n,a n op t i o n a l s e c o nd t im i ng mod e wa s a d d e d:GPS s y n ch r on i z e d o p e r a t i o n.T h e s y n c h r o n i z e d mod e o f o p e r a t i o n w i l l a l l ow 3GPP W C D M A t o b e smoo t h l y i mp l eme n t e d i n t h o s e l o c a t i on s t h a t c u r r e n t l y u s e t h e T IA/E I A-95B CD M A s y s t em (GPS s yn ch r o n i z e d).T h e a c c u r a t e s y n c h r o n i z a t i o n o f t h e GPS l o c k ed mod e a l l ows mob i l e s a nd b a s e s t a t i on s t o s e a r c h ov e r s ho r t, we l l k n o wn t ime i n t e r v a l s wh en a c qu i r i n g s i g n a l s.T h i s l owe r s t h e p r o c e s s i ng r e q u i r emen t s i n t h e mob i l e

s t a t i o n s a n d r e du c e s t h e c o mp l e x i t y o f s o f t h a n do f f s.Howeve r,t o a c h i e v e t h i s s y n ch r o n i z a t i o n,t h e GPS s a t e l l i t e s y s t em (o r s o me o t h e r me t hod) mu s t b e u s e d a s t h e ma s t e r t i ming s ou r c e.Th i s r e qu i r e s t h a t e a c h b a s e s t a t i o n mu s t h a v e a c l e a r l i n e-o f-s i g h t a n t e n n a t o t h e GPS s a t e l l i t e s. Howeve r, wh en op e r a t i ng t h ei n a s y n c h r o nou s mod e,t h e 3GPP s y s t em h a s no s u c h r e q u i r emen t.T h i s do e s ma k e s y s t em a c c e s s mor e d i f f i c u l t a n d i n c r e a s e s s e a r c h t ime.G r e a t e f f o r t h a s b e e n

a pp l i e d t o t h e 3GPP s y s t e m t o r e du c e t h e s e e f f e c t s.The

b e n e f i t so f a s y n ch r o n ou s mod e a r e:i t e l i mina t e s t h e

c o s t o f t h e GPS r e c e i v e r,a n

d i t

e l im i n a t e s t h e r e q u i r emen t t h a t t h e b a s e s t a t i o n b e p h y s i c a l l y l o c a t e d s o t h a t GPS s a t e l l i t e r e c e p t i o n i s p o s s i b l e.T h e a s y n ch r o n ou s mod e a l l ows s i mp l e i n s t a l l a t i o n s i s s u c h l o c a t i o n a s t u n n e l s a n d s u bway s wher e GPS

s a t e l l i t e r e c e p t i o n i s p r o b l e ma t i c.

No t e s:

S l i d e : 5

No t e s :

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Ne twork Lay e r

Da ta L ink Laye r

Phy s i c a l Laye r

Laye r 3R R C

Med ium Acc e s s Con t r o l Laye r 2Laye r 1

M A C

RLC

Rad i o L ink Con t r o l Rad i o Re sou r c e Cont r o l 3GPP Protocol Structure The p r o t o c o l s t r u c t u r e o f t h e 3GPP s y s t e m c l o s e l y f o l l ows t h e i n d u s t r y s t a nd a r d 7 l a y e r mod e l . T h e Ne twor k L ay e r (L ay e r 3) i s r e s p on s i b l e f o r c o nne c t i n g s e r v i c e s f r om t h e Netwo r k t o U s e r Equ i p men t . The Ra d i o Re s o u r c e Con t r o l (RRC ) b l o c k a t l a y e r t h r e e h and l e s t h e c onn e c t i o n , c o n f i g u r a t i o n a n d r e l e a s e o f b e a r e r s e r v i c e s a n d t h e r e q u i r e d c o r r e s pond i n g r a d i o r e s o u r c e s . T h e d a t a L i nk La y e r (Laye r 2) i s c ompo s e d o f t wo mai n f u n c t i o n a l b l o c k s : t h e R a d i o L i nk Con t r o l (RLC ) a nd Me d i um Acce s s C on t r o l (MAC) b l o ck s . The RLC b l o c k i s r e s p on s i b l e f o r : t r a n s f e r o f u s e r d a t a , e r r o r c o r r e c t i o n , f l ow c o n t r o l , p r o t o c o l e r r o r d e t e c t i o n a nd r e c ov e r y , a nd c i ph e r i n g . Th e e r r o r c o r r e c t i on f u n c t i o n o f t h e RLC i n c l u d e s s u c h f u n c t i o n s a s S e l e c t i v e R ep e a t a n d Go -Bac k -N r e t r a n s mi s s i o n f o r l o s t d a t a . T h e C iph e r i n g f u n c t i o n u s e s e n c r y p t i o n t e c hno l o gy t o p r e v e n t unwant e d i n t e r c e p t i on o f t r a n sm i t t e d d a t a . T h e MAC f u n c t i o n a t l a y e r 2 i s r e s p on s i b l e f o r mapp i n g b e twe e n l o g i c a l c h a n n e l s a n d t r a n s po r t c h a nn e l s a s we l l a s p r o v i d i n g t h e mul t i p l e x i ng /d e -mu l t i p l e x i n g f un c t i o n o f v a r i o u s l og i c a l c h ann e l s e f f i c i e n t l y on t o t h e s ame t r a n s p o r t c h a nn e l . T h e P hys i c a l L a y e r (L ay e r 1) map s t h e t r a n s p o r t c h a n n e l s o n t o t h e phy s i c a l c h a n n e l s a n d p e r f o rm s a l l o f t h e RF f u n c t i o n s n e c e s s a r y t o make t h e s y s t em wor k . T h e s e f u n c t i o n s i n c l u d e s s u c h op e r a t i on s a s : f r e q u e n cy a n d t ime s y n ch r on i z a t i on , r a t e ma t c h i n g , s p r e a d i ng a n d modu l a t i o n , powe r c on t r o l , a n d s o f t h a n do f f .

S l i d e:6

3GPP Network Support

Designed to Work with Two Networks:

?MAP Network:

?GSM Network

?ANSI-41 Network:

?U.S. Standard

Required to Produce a 3G “World Phone”

One o f t h e o u t c ome s o f t h e h a rmon i z a t i o n e f f o r t s w a s t h e i n c o r p o r a t i o n o f t wo d i f f e r e n t n e two r k o p t i o n s.T h e s e two

n e two r k o p t i o n s a r e t h e MAP n e two r k u s e d i n many GS M s y s t ems,a n d t h e ANS I-41Ne twor k c ommon l y u s e d i n No r t h A me r i c a.T h e d u a l n e two r k o p t i o n wa s a dop t e d t o a l l ow t h e f u t u r emanu f a c t u r e o f “wor l d p h o n e s”.T h e Re l e a s e99

v e r s i o n o f t h e s t a n d a r d o n l y s u ppo r t s t h e MAP n e twor k o p t i on.A f u t u r e r e l e a s e wi l l d e f i n e t h e ANSI-41o p t i o n t h a t w i l l a l l ow f u t u r e3GPP p hon e s t o r o am f r om Eu r op e o r t h e Fa r E a s t t o t h e Amer i c a s.Giv en t h e p r e s s u r e t o r o l l o u t t h e

i n d i v i d u a l s y s t em s a r o u nd t h e wo r l d,t h e du a l n e two r k 3GPP phon e may n o t b e p r o d u c e d f o r q u i t e s o me t ime.

No t e s:

S l i d e:7

Transport vs. Physical Channels

3GPP Supports the Concept of Multiple

Services Sharing a Physical Connection

The Concept of “Transport”Channels is used

to Support these Services

Adds an Extra Layer Where Transport

Channel are Multiplexed together Prior to

Transmission on a Physical Channel

The 3GPP s y s t em i n t r o d u c e s t h e c o n c e p t o f“t r a n s p o r t”c h a nn e l s t o s u ppo r t s h a r i n g p h y s i c a l r e s o u r c e s b e t ween mu l t i p l e s e r v i c e s.E a c h s e r v i c e,s u c h a s d a t a,f a x,vo i c e,o r s i g n a l i n g a r e r o u t e d i n t o d i f f e r e n t t r a n s po r t c h ann e l s b y t h e u ppe r

s i g n a l i ng l a y e r s.T h e s e s e r v i c e s may h a v e d i f f e r e n t d a t a r a t e s a n d e r r o r c on t r o l me ch a n i sms.The s e t r a n s p o r t c h a nn e l s a r e t h e n mu l t i p l e x e d a s r e q u i r e d p r i o r t o t r a n smi s s i o n v i a o n e o r mo r e p h y s i c a l c h ann e l s.H i g h d a t a r a t e s e r v i c e s o r a

c omb i n a t i o n o f l owe r r a t e s t r a n s po r t c h a nn e l s may b e mu l t i p l e x e

d i n t o s

e v e r a l p hy s i c a l c h a nne l s.T h i s

f l e x i b i l i t y a l l ow s nume r ou s t r a n s po r t c h ann e l s(s e r v i c e s)o f v a r y i n

g d a t a r a t e s t o b e e f f i c i e n t l y a l l o c a t e d t o p hy s i c a l c

h a nn e l s.B y

mu l t i p l e x i n g t h e s e t r a n s po r t c h a n n e l s e f f i c i e n t l y,s y s t em c a p a c i t y i s o p t im i z e d.F o r e x a mp l e,i f t h e a gg r e g a t e d a t a r a t e o f t h r e e t r a n s po r t c h a nn e l s e x c e e d s t h e ma x imum o f a s i n g l e phy s i c a l c h a n n e l,t h e n t h e d a t a c a n b e r o u t e d t o two l o we r r a t e p h y s i c a l c h ann e l s t h a t c l o s e l y ma t c h t h e t o t a l r e q u i r e d d a t a r a t e.

No t e s:

S l i d e:8

Downlink Physical Channels

CPICH(Common Pilot Channel).

P-CCPCH(Primary Common Control Physical Channel).

S-CCPCH(Secondary Common Control Physical Chan).

SCH(Synchronization Channel).

DPCH(Dedicated Physical Channel).

PDSCH(Physical Downlink Shared Channel).

AICH(Acquisition Indication Channel).

PICH(Page Indication Channel).

The3GPP d own l i n k i s c o mpo s e d o f a number o f p h y s i c a l c h ann e l s.T h e C ommon P i l o t Cha nn e l(CP ICH)i s u s e d a s a t im i n g a nd f r e qu en cy r e f e r e n c e b y mob i l e s t a t i o n s.T h e P r ima r y Com mon Con t r o l P h y s i c a l Cha nn e l(P-CCPCH)c a r r i e s a t r a n s po r t c h a nn e l c a l l e d t h e B r o a d c a s t Channe l(BCH). The BCH c a r r i e s t h e s y s t em ov e r h e a d i n f o rma t i o n. Th e

Se cond a r y Common Con t r o l P h y s i c a l Channe l(S-CCPCH)c a n c a r r y t h e F o rwa r d Acc e s s Ch ann e l o r t h e Pag i n g Channe l(FACH o r PCH, bo t h o f wh i c h a r e t r a n s po r t c h ann e l s).T o a i d mob i l e s y n ch r o n i z a t i o n t o t h e n e two r k,e a c h

b a s e s t a t i o n a l s o t r a n sm i t s t h e S y n

c Ch a nn e l(S CH).The ma i n b u i l

d i n g b l o c k o f t h

e d o wn l i n k i s t h e Ded i c a t e d P h y s i c a l Channe l(DPCH)t h a t c a r r i e s t h e Ded i c a t e d Cha nn e l(DCH, wh i c h i sa t r a n s po r t c h ann e l).T h e DPCH i s c o mpo s e d o

f two s u b-c h a n n e l s:t h e Dedi c a t e d Phy s i c a l Da t a C h anne l(DPDCH) a nd t h e Ded i c a t e d Phy s i c a l Cont r o l Cha nn e l (DPCCH).Oth e r down l i nk c h a nn e l s i n c l u d e t h e P h y s i c a l Down l i n k S h a r e d Ch ann e l(PDSCH)wh i c h c a n c a r r y

i n f o rma t i o n t o mu l t i p l e mob i l e s a t t h e s a me t ime.T h e Acqu i s i t i o n I nd i c a t i on Ch a nn e l(AICH) i s u s e d t o i n d i c a t e t o a mob i l e t h a t t h e b a s e s t a t i o n h a s a c qu i r e d t h e mob i l e’s a t t empt t o c o n t a c t t h e n e t wo rk.The P a g e I n d i c a t i o n Channe l

(P ICH)i n f o r ms mob i l e s wh en p a g e s d i r e c t e d t o t h a t mob i l e w i l l b e s e n t i n a n f u t u r e P a g i n g Ch ann e l s l o t.

No t e s:

S l i d e:9

Pilot Structure

3GPP Uses Two Types of Pilot Channels:

?Code Based Pilot (CPICH -Common Pilot Channel)

?Used To Broadcast Timing Information to All Mobile Stations Operating in a Cell or Sector

?Embedded Pilot Signals:

?Some Downlink Channels also Included Embedded Pilot Information

?Pilot Data is Time Multiplexed into the Channel

?Used by Mobiles to Send Timing Information to Base Stations

Af t e r h a rmon i z a t i o n,t h e3GPP W C D M A s y s t em h a s a d o p t e d t wo t y p e s o f p i l o t c h a nn e l s t r u c t u r e s:t h e c od e b a s e d p i l o t c h ann e l a n d t h e emb edd ed p i l o t c h ann e l.I n t h e d own l i n k,t h e3GPP s y s t e m u s e s a s i n g l e c ommon p i l o t c h a nn e l

(CP ICH)t h a t i s a s s i gn ed a un i q u e s p r e a d i n g c o d e.T h i s a l l ows a l l mob i l e s i n t h a t c e l l t o d e cod e t h e p i l o t c h a nn e l a nd

u s e i t a s a t imi n g r e f e r e n c e.T h e3GPP s y s t em a l s o u s e s a n e mbedde d p i l o t i n s o me o f t h e d o wn l i n k p h y s i c a l c h a n n e l s. The p i l o t c o n s i s t s o f a k n o wn p a t t e r n o f d a t a b i t s t h a t i s mu l t i p l e x e d i n t o t h e c h a nn e l’s d a t a s t r e am.Th i s k nown p a t t e r n c a n t h e n b e d e c od ed by t h e r e c e i v e r a n d u s e d a s a n a d d i t i o n a l t im i n g r e f e r e n c e s i gn a l.Depend i n g u pon t h e s t r u c t u r e o f a g i v e n p hy s i c a l c h a nn e l,t h e n u mbe r o f p i l o t c h ann e l d a t a b i t s p e r f r ame c h a n g e s.T h e CP I CH a l l ows mob i l e s t a t i o n s t o u s e c o h e r e n t d e t e c t i on t o i n c r e a s e d emodu l a t i on p e r f o rmanc e.

No t e s:

S l i d e:10

Downlink CPICH

Common Pilot Channels (CPICH):

?Primary CPICH:

?Modulated with 1+j pattern

?Always Uses the 256 bit OVSF Spreading Code 0

?Always Uses the Cell’s Primary Scrambling Code

?One Per Cell and is Broadcast Over the Entire Cell

?Secondary CPICH:

?Same as the Primary CPICH Except -

?Assigned Arbitrary 256 bit OVSF Spreading Code

?Can use the Primary or a Secondary Scrambling Code

?There can be Any Number of Them

The d o wn l i n k u s e s a C ommon P i l o t Cha nn e l(CP ICH)t o s e nd t i ming i n f o rmat i o n t o mob i l e s t a t i o n s. Mob i l e s t a t i o n s

u s e t h e p i l o t d a t a t o ma i n t a i n s y n c h r o n i z a t i o n wi t h t h e b a s e s t a t i o n a n d a s a c o h e r e n t r e f e r e n c e t o p e r f o rm s y n ch r onou s d emodu l a t i o n.T h e3GPP W C D M A s y s t em h a s s e v e r a l t y p e s o f Common P i l o t Channe l s.E v e r y c e l l h a s o n e a n d on l y on e P r i ma ry CP ICH. Th i s c h a n n e l i s u nmodul a t e d(1+j p a t t e r n o n t h e I a nd Q c h ann e l s)a n d i s s p r e a d w i t h a256b i t

O VSF c od e t h a t i s f i x e d:a l l c e l l s u s e t h e s ame256b i t c o d e-wh i c h i s c o d e n umb e r0(mor e o n OVSF c od e s i n a

minu t e).T h e P r ima r y CP I CH i s a lway s s c r amb l e d b y t h e b a s e s t a t i o n’s p r ima r y s c r a mb l i n g c o d e.

A Se c ond a r y CP ICH i s s i mi l a r t o a P r i ma ry CP ICH ex c e p t t h a t t h e y a r e f r e e t o b e a s s i g n e d a ny 256 b i t OO VSF

s p r e a d i ng c o d e a n d c a n u s e e i t h e r t h e p r i ma ry o r a n y o f t h e s e c ond a r y s c r a mb l i n g c o d e s f o r t h e a s s o c i a t e d b a s e s t a t i o n. The r e c a n b e a ny n u mbe r o f S e c o nd a r y CP ICHs. The p r ima r y u s e o f t h e Se cond a r y CP ICH wi l l b e i n t h e f u t u r e when

b e am f o rmed a n t e n n a s a r e i mp l eme n t e d.The s e b e am f o rmed a n t e n n a s w i l l t r a n smi t b a s e s t a t i o n s i g n a l s t o i n d i v i d u a l mob i l e s t a t i o n s t o r e du

c e ov e r a l l i n t e r f e r e n c e l e v e l s wh i l e ma i n t a i n i n g a q u a l i t y l i n k.Beam f o rme

d r

e c e p t i o n a n t e nn a s wi l l a l l ow b a s e s t a t i o n s t o t r a c k t h e l o c a t i on a mob i l e t o ma i n t a i n s i gn a l q u a l i t y.I n t h e s e c a s e s,a s e c ond a r y CP ICH

c h ann e l i s n e e

d ed s o t h a t t h

e mob i l e s t a t i on c a n d e cod e t h e b e am

f o r med s i gn a l t h a t i s d i r e c t e d t o i t.

No t e s:

S l i d e:11

Downlink P-CCPCH

The P-CCPCH(Primary Common Control Physical Channel)

Transmits the BCH (Broadcast Channel) Transport Channel.

Sends Cell Information.

Rate Is Fixed to 27 kbps.

Broadcast over the Entire Cell.

The P-CCPCH Does Not Contain Pilot, Power Control, or Rate

Information.

Every Cell Uses OVSF Code 1 (256 bit).

The P-CCPCH phy s i c a l c h a nn e l c a r r i e s t h e BCH t r a n s p o r t c h ann e l.T h e BCH t r a n sm i t s c e l l s p e c i f i c i n f o r ma t i o n t h a t mob i l e s n e e d t o c ommun i c a t e w i t h t h e n e two r k.T h e BCH i s a lway s f i x e d t o a d a t a r a t e o f27k s p s. T h e P-CCPCH i s

t r a n smi t t e d t o t h e e n t i r e c e l l o r s e c t o r. T h e P-CCPCH i s a lway s s p r e a d w i t h t h e s ame256b i t O VSF c od e -wh i c h i s

c o

d e1.

No t e s:

S l i d e:12

P-CCPCH Frame Structure

Each Frame is 10 milliseconds in Duration.

Each Frame is Divided into 15 Timeslots:

?Data Rate is Fixed to 27,000 bps

?18 Data symbols are Sent in each Timeslot

?The P-CCPCH Does Not Transmit in the first 66.7 usec

P-CCPCH

The P r ima r y Com m on Con t r o l P hy s i c a l C h anne l u s e s a f i x e d,10ms f r a me s t r u c t u r e.T h e f r amed d a t a r a t e f o r t h e P-CCPCH i s f i x ed t o27,000 b i t s p e r s e c o n d.E a c h f r ame o f t h e P-CCPCH i s f u r t h e r b r o k e n i n t o15t ime s l o t s o f667u s e c. Each t i mes l o t i s d i v i d ed i n t o two s e c t i o n s:a n o f f p e r i o d wh e r e n o d a t a i s t r a n sm i t t e d,a n d a d a t a po r t i o n t h a t c a r r i e s t h e BCH i n f o rmat i o n.T h e P-CCPCH do e s n o t s e n d a n y d a t a i n t h e f i r s t66.7u s e c o f e a c h t i mes l o t.T h i s i s d o n e t o r e d u c e

t h e e f f e c t s o f t h e S y n c c h a nn e l wh i c h d i r e c t l y i n t e r f e r e s w i t h t h e o t h e r c h a nn e l s i n t h e down l i nk (mor e o n t h i s i n a minu t e).T h e d a t a p o r t i o n o f e a c h t imes l o t c a r r i e s18d a t a b i t s o f t h e BCH t r a n s p o r t c h ann e l.T h i s p r o v i d e s a f i x e d r a t e o f27,000b i t s p e r s e c ond f o r t h e BCH.

No t e s:

S l i d e:13

P-CCPCH Channel Coding

The c h a nn e l c od i n g o f t h e P-CCPCH b e g i n s wi t h a b l o ck o f d a t a f r om t h e BCH t r a n s p o r t c h a n n e l.T h i s b l o c k o f d a t a

c a r r i e s t h e a c t u a l mes s a g e po r t i o n o f t h e BCH (s y s t em i n f o r ma t i o n).S e v e r a l o t h e r

d a t a b l o c k s a r

e a d d ed t o t h e BCH

d a t a.F i r s t,t h

e S y s t e m F r a me Numbe r(SFN)i s c a r r i e d b y12b i t s o

f d a t a.T h e SFN i s u s e d b y t h e mob i l e t o a l i

g n d a t a r e c e i v e d f r o m v a r i ou s c e l l s d u r i ng s o f t

h a n dof f.A t we l v e b

i t CRC i s a l s o a d d e d t o a l l ow t h e mob i l e t o v e r i f y t h e

r e c e i v e d d a t a.E i g h t t a i l b i t s a r e a l s o a d d e d t o r e s e t t h e i n i t i a l s t a t e o f t h e c onvo l u t i o n a l e n c ode r t o a l l z e r o e s s o a s t o b e r e a d y f o r t h e n ex t f r ame o f d a t a.At t h i s p o i n t,t h e c o mb i n e d d a t a i s p a s s e d t h r o ugh a on e-h a l f r a t e c onvo l u t i o n a l

e n cod e r t h a t d oub l e s t h e d a t a r a t e t o25.6kbp s.Ra t e ma t c h i n g i s p e r

f o rmed t o b r i n

g t

h e f

i n a l r a t e u p t o27k bp s.

No t e s:

S l i d e:14

Downlink Sync Channel

The Primary SCH is:

?An unmodulated, 256 bit Gold Code

?The Code is Sent at the Beginning of each Timeslot

?All Base Station use the Same, 256 bit Gold Code

The Secondary SCH is:

? A Sequence of 15, unmodulated, 256 bit Gold Codes

?The Pattern is Sent using the first 256 bits of each Timeslot (15 )

?The Pattern of Codes (64 total) correspond to the Scrambling Code (Long Code) Group

being used by the Base Station

Both Channels are Orthogonal to Each Other, but are NOT

Orthogonal to the Other Channels.

The Syn ch r o n i z a t i o n c h a nne l i s c o mpo s e d o f two i n d i v i d u a l c h ann e l s:t h e P r ima r y SCH a n d S e c ond a r y SCH. Th e

pu r p o s e o f t h e s e two c h a n n e l s i s t o:p r o v i d e a ni n d e n t i f y i n g s i g n a l f o r e a c h b a s e s t a t i o n,a n d a s a t i ming r e f e r e n c e f o r

e a c h b a s e s t a t i o n.T h e P r i ma ry S yn c t r a n sm i t s a n u n modu l a t e d,256b i t Go l d Code p a t t e r n a t t h e3.84 Mc p s r a t e.T h e 256 b i t s a r e s e n t o n c e i n t h e

f i r s t10% o f e a c h t ime s l o t(256b i t s a t3.84Mcps= 66.7u s e c,e a c h t i mes l o t i s667u s e c). Th i s Go l d c o d e i s t h e s ame f o r e v e r y b a s e s t a t i o n. Mobi l e s s e a r c h f o r t h i s p a t t e r n when l ook i n

g f o r s u i t a b l e b a s e

s t a t i o n s t o u s e.

The S e c ond a r y Syn c c h a nne l p r o v i d e s a“h i n t”t o t h e mob i l e o f wh i c h s c r a mb l e c od e t h e b a s e s t a t i o n i s u s i n g.I n s t e a d

o f u s i n g a s i n g l e256b i t c od e,t h e S e c o nd a r y Sync u s e s a s p e c i f i c s e q u e n c e o f15,256 b i t c od e s i n e a c h f r ame.The r e

a r e64p a t t e r n s o f c o d e s f o r t h e S e c ond a r y Syn c c h a nne l.T h e p a t t e r n u s e d by t h e Se cond a r y S yn c c h a nn e l i nd i c a t e s t h e s c r ambl e c o d e g r o up t h a t t h e

b a s e s t a t i o n i s u s i n g.I n e a

c h s c r amb l e c o

e g r o u p,t h e r e a r e8p o s s i b l e s c r amb l e c o d e s. Once t h e mob i l e r e a d s t h e S e c ond a r y S yn c c h a nn e l a nd d e t e rm i n e s t h e p a t t e r n i t i s u s i ng,t h e mob i l e t h e n s e a r c h e s

f o r t h e p r i ma ry s c r amb l e c o d e f r om t h e i n d i c a t e d

g r o u p.I t i s impo r t a n t t o r e a l i z e t

h a t t h e P r ima r y a nd S e c ond a r y Syn c

c h ann e l s a r e o r t h o gon a l t o e a c h o t h e r,b u t a r e n o t o r t h ogon a l t ot h e o t h e r c h ann e l s i n t h e c e l l.

No t e s:

S l i d e:15

Sync Frame Structure

3ULPDU\6\QF 6HQGV VDPH&RGH LQ HDFK6ORW

6HFRQGDU\6\QF 6HQGV D3DWWHUQ RI&RGHV LQ HDFK)UDPH

Fo r e a c h10ms f r a me,b o t h t h e P r ima r y a n d Se cond a r y S yn c c h a nn e l s on l y t r a n sm i t i n t h e f i r s t10% o f e a c h o f t h e15

t ime s l o t s.T h e c o d e s s e n t by t h e s e two c h ann e l s a r e t a k en f r o m a s e t o f256b i t l o n g c o d e s.T h e P r ima r y Syn c c h a nne l s e n d s t h e s ame 256 b i t c o d e i n e a c h t ime s l o t.Eve r y b a s e s t a t i o n u s e s t h e s ame256b i t c o d e f o r t h e P r ima r y Syn c Channe l.

The S e c ond a r y Syn c c h a nne l s e n d s a p a t t e r n o f256 b i t l o n g c od e si n e a c h f r ame t a k en f r om a s e t o f64c o d e p a t t e r n s. The r e a r e16un i q u e c o d e s u s e d t o f o rm t h e s e64c o d e p a t t e r n s.T h i s p a t t e r n i s r e p e a t e d i n e a c h f r ame.I n t h i s e x amp l e, t h e S e c ond a r y Syn c c h a nne l i s s e nd i n g t h e S c r amb l e Group1p a t t e r n.T h i s me ans t h a t t h e b a s e s t a t i o n s e n d s t h e

f o l l ow i ng256 b i t c o d e s i n t h e15t ime s l o t s o f e a c h f r a me:c o d e 1,1,2,8,9,10,15,8,10,16,2,7,15,7,16.On c e t h e mob i l e r e a d s t h i s p a t t e r n,i t knows wh i c h s c r ambl e c o d e

g r o up c on t a i n s t

h e s c r ambl e c o d e b e

i n g u s e d b y t h e c e l l.T h e mob i l e mu s t t h en s e a r c h t h r o u gh t h e8s c r amb l e c o d e s i n t h i s g r o up t o f i n d wh i c h s c r ambl e c o d e(c a l l e d t h e p r ima r y

s c r ambl e c o d e)t h e c e l l i s u s i n g.T h e mob i l e c a nno t c ommun i c a t ewi t h t h e b a s e s t a t i o n u n t i l i t h a s i d e n t i f i e d t h e e x a c t p r ima r y s c r a mb l e c od e b e i n g u s e d.

No t e s:

S l i d e : 16

No t e s :

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

S e condary

SCH

Pr imary

SCH Q

Primary & Secondary Sync

The o v e r a l l b l o ck d i a g r am o f t h e Sync c h ann e l s h ows t h a t t h e P r ima r y a n d S e c o nd a r y Sync c h ann e l s a r e s ummed a t I a nd Q a nd t h e n t r a n sm i t t e d (s e n t d i r e c t l y t o t h e I /Q modu l a t o r ) wi t h o u t a ny f u r t h e r c o d i n g . T h e g a t i ng n a t u r e o f t h e s e c h ann e l s i s d e p i c t e d a s a n o u t p u t s wi t c h t h a t o n l y c o nne c t s t h e s e s i g n a l s t o t h e I /Q modu l a t o r d u r i n g t h e f i r s t 256 c h i p s o f e a c h t imes l o t . As s h own h e r e , t h e r e a r e 16, 256 b i t g o l d c od e s t h a t a r e u s e d f o r t h e Se cond a r y S yn c Cha nn e l . Remembe r t h a t t h e r e a r e 64 p o s s i b l e p a t t e r n s o f t h e s e c o d e s t h a ta r e s e n t o n t h e S e c o nd a r y Sync c h ann e l . I n e a c h f r a me , t h e r e a r e o n l y 15 t ime s l o t s , s o i n a ny o n e f r ame , o n l y 15 c o d e s a r e s e n t . T h e s e 15 c od e s a r e s e l e c t e d f r om t h e 16 a v a i l a b l e f o r e a c h p a t t e r n .

S l i d e:17

Downlink S-CCPCH

The S-CCPCH (Secondary Common Control Physical Channel) Sends

the FACH(Forward Access Channel) and the PCH(Paging Channel)

Transport Channels.

?The FACH is Pages Mobiles when Their Location is Known.

?The PCH is Pages Mobiles when Their Location is Not Known.

?The FACH and PCH Can be Combined on one SCCPCH or Sent on Separate SCCPCH Channels.

The S-CCPCH Has No Power Control Data, but Optionally Carries Rate

Information.

The Rate is Fixed in a Cell but Can Be Different between Cells

Depending on Cell Loading.

The S e c ond a r y Common Con t r o l Phy s i c a l Ch a nn e l(S-CCPCH)t r a n sm i t s o n e o f t wo t r a n s po r t c h ann e l s:t h e Fo rwa r d Acce s s C h anne l(FACH)a nd t h e Pag i n g C h anne l(PCH). The FACH i s u s e d t o p a g e mob i l e s when t h e i r l o c a t i o n i s known.T h e P CH i s u s e d t o p a g e mob i l e s when t h e i r l o c a t i o n i n t h e s y s t e m i s n o t k n o wn.I f bo t h t r a n s po r t c h a n n e l s a r e u s e d i n a c e l l,t h e y c a n b e c o mb i n e d i n t o on e S-CCPCH ch ann e l o r b e s e n t o n i n d e p end e n t S-CCPCH c h ann e l s.L i k e

t h e P-CCPCH,t h e S-CCPCH h a s n o a s s o c i a t e d p owe r c o n t r o l d a t a. Howe v e r,t h e S-CCPCH c a n o p t i o n a l l y c a r r y r a t e

i n f o rma t i o n(TFCI).I n a l l c a s e s,t h e f r a med b i t r a t e o f a n S-CCPCH i s f i x ed i n a c e l l,bu t c a n v a r y b e twe e n d i f f e r e n t

c e l l s t o a c c ommoda t e

d i f f

e r i n g l e v e l s o

f l o a d i n g(n umb e r o f p a

g e s t

h a t n e e d t o b e s e n t

i n a c e l l). On e op t i o n f o r t h e FACH i s t h e u s e o f h i g h l y d i r e c t i on a l t r a n sm i t a n t e n n a s t o t r a n sm i t t h e F ACH i n a n a r r ow l o b e.T h e s e b e am f o r med

a n t e n n a s t r a c k t h e l o c a t i o n o f t h e r e c e i v i n g mo

b i l e s t a t i o https://www.doczj.com/doc/ef10492624.html, i n g s t e e r e d,n a r r o w b e a m an t e nn a s r e du

c e s t h e o v e r a l l

l e v e l o f i n t e r f e r e n c e.R e du c e d i n t e r f e r e n c e t r a n s l a t e s d i r e c t l y i n t o a n i n c r e a s e i n t h e c e l l’s c a p a c i t y.

No t e s:

S l i d e:18

S-CCPCH Frame Structure

Each Frame is 10 milliseconds in Duration.

Each Frame is Divided into 15 Timeslots:

?Pilot Data is Optional

?TFCI information (Transport Format Combination Indicator) is Optional

S-CCPCH

The S-CCPCH f r ame s t r u c t u r e i s a l s o b a s e d u p on 10ms f r a mes. Un l i k e t h e P-CCPCH,t h e S-CCPCH t r a n sm i t s d a t a

c on t i n uou s l y i n a l l po r t i o n s o f e a c h t ime s l o t.Op t i o n a l l y,T FC I i n f o rma t i o n c a n b e s e n t a t t h e b e g i nn i n g o f e a c h

t ime s l o t. Whe n TFCI i s p r e s e n t,t h e r a t e o f t h e S-CCPCH i s v a r i a b l e.Wi t h o r w i t h o u t t h e TFCI,t h e d a t a r a t e o f t h e mes s a g e p o r t i o n o f t h e S-CCPCH go e s f r om 15 kbp s u p t o1,844k b p s I n t h i s e x a mp l e,t h e S-CCPCH i s r u n n i n g a t 30,000 b i t s p e r s e c o n d(me s s a g e p o r t i o n a t15k bp s) wi t h2b i t s a l l o c a t e d i n e a c h t i mes l o t f o r t h e o p t i o n a l TFCI

i n f o rma t i o n a nd8b i t s i n e a c h t ime s l o t f o r t h e p i l o t i n f o rma t i o n.T h e p i l o t d a t a i s a l s o o p t i o n a l on t h e S-CCPCH.

No t e s:

S l i d e:19

TFCI Function

Transport Format Combination Indicator is an Optional Field that

Describes the Services in Use.

The TFCI Message is Ten Bits in Length.

Message Is Reed-Muller Coded (32,10) and Punctured Down to 30,10.

Is Sent as Two Bits per Slot -Equals 30 Bits per Frame.

Allows the Receiver to Perform Explicit Rate Detection.

If Not Used, the Receiver Must Perform Blind Rate Detection.

The o p t i o n a l T r an s p o r t F o r ma t Comb i n a t i o n I nd i c a t o r(TFCI)i s u s e d t o c o nv e y t h e n umbe r o f b i t s i n e a c h s e r v i c e f o r e a c h f r ame.T h e TFCI wo r d h a s t e n i n f o rma t i o n b i t s(p e r f r a me).T h i s mea n s t h a t t h e r e a r e a max imum o f2=1024

po s s i b l e c omb i n a t i o n s o f s e r v i c e a nd b i t r a t e s.The p u r p o s e o f t h e TFCI i s t o h e l p t h e r e c e i v e r d e t e r mine t h e a c t i v e

s e r v i c e s a n d n umbe r o f b i t s i n e a c h s e r v i c e. When TFCI i s n o t u s e d,t h e r e c e i v e r mu s t“b l i n d d e t e c t”t h e n umb e r o f

s e r v i c e s a n d t h e b i t r a t e f o r e a c h.To e n s u r e t h a t t h e T FC I i n f o rma t i o n i s r e l i a b l y t r a n s mi t t e d,a d d i t i on a l e r r o r c o r r e c t i o n i s a p p l i e d t o t h e TFCI d a t a p r i o r t o t r a n sm i s s i on. The t e n b i t s o f t h e TFCI wo r d a r e e n cod ed w i t h Reed-Mul l e r s e c o n d

o r d e r c od i n g t h a t i n c r e a s e s t h e l e n g t h o f t h e TFCI wo r d t o32b i t s.S i n c e e a c h t ime s l o t s e nd s t wo TFCI b i t s,t h e c od ed TFCI i n f o rmat i o n mu s t b e pun c t u r e d d o wn t o30,10 c od i n g.T hu s two b i t s a r e s e n t i n e a c h o f t h e15t imes l o t s t o

t r a n smi t t h e e n t i r e30b i t s i n e a c h f r ame.

No t e s:

S l i d e:20

Paging Indicator Channel (PICH)

Designed to Increase Battery Life for “Sleep Mode”.

Each Phone is Assigned:

?A Paging Slot to Check for Paging Messages on the S-CCPCH (Paging Channel)

?An Associated Paging Indicator Position on the PICH

The PICH is Aligned to Transmit Ahead of the Associated Paging

Slot on the S-CCPCH

Mobile Decodes the PICH Channel:

?Active Indicator Tells Mobile that a Page is Coming

?No Indicator Tells Mobile to Return to Sleep Mode without Reading the Paging Channel Slot

To p r o v i d e t h e l o n g e s t p o s s i b l e b a t t e r y l i f e,3GPP u s e s a s l o t t e d p a g i n g s c h eme t h a t a l l ows p h on e s t o e n t e r a l ow powe r “s l e e p”mode.T h e mob i l e s o n l y“wak e s-u p”f r om t h e s l e e p mod e a t d i s c r e t e t i mes (t i mes l o t s)t o c h e ck f o r a p a g e.T h e wake u p t imes a r e n e go t i a t e d d u r i ng r e g i s t r a t i o n f o r e a c h mob i l e.To f a c i l i t a t e t h i s s l e e p o p e r a t i o n,t h e P a g i n g I n d i c a t o r Channe l(P ICH)i s u s e d t o i n f o rm e a c h mob i l e i f t h e r e wi l l b e a p a g e f o r i t i n i t s n e x t a s s i gn ed p a g i n g s l o t. T h e P ICH i s a l i g n e d s o t h a t t h e i nd i c a t o r s a r e t r a n s mi t t e d b e f o r e t h e a s s o c i a t e d p a g i n g s l o t on t h e S-CCPCH.

W hen a mob i l e s c o mes o u t o f s l e e p mod e,i t mus t f i r s t d e c od e t h e p a g i ng i n d i c a t o r(P I)o n t h e P I CH t h a t i s a s s o c i a t e d wi t h i t s p a g i n g s l o t t o d e t e r mine i f a p a g e i s c o n t a i n e d i n t h e u p com i ng p a g e me s s a g e.I f t h e P I i s e q u a l t o1,t h en t h e phon e mus t s t a y awak e a n d d e cod e t h e P a g i n g c h ann e l.I f t h e P I i s e qu a l t o0,t h e n t h e mob i l e may r e t u r n t o s l e e p mod e un t i l i t s n e x t a s s i g n e d p a g i n g s l o t.

No t e s: