Đề Cương chuyển giao công nghệ 3G- WCDMA
Transcript of Đề Cương chuyển giao công nghệ 3G- WCDMA
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HC VIN CNG NGH BU CHNH VIN THNGKHOA CNG NGH THNG TIN
BI TP LN
TI: CHUYNGIAO TRONG H THNG 3GWCDMA
Ging vin hng dn: ....................................Mn : Tng Quan Vin Thng
Nhm : 14Sinh vin thc hin : NG TH GIANG
NGUYN T.THANH MAION XUN QUNH
Lp : D10CN2
H NI-2013
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BI TP LN
MN: TNG QUAN VIN THNGGING VIN:LP: D10CN2NHM: 14 BI: CNG CHUYN GIAO TRONG
H THNG 3G WCDMATHNH VIN:
NG TH GIANG
NGUYN TH THANH MAION XUN QUNH
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BI LM:
PHN A: PHN CNG: TI: CHUYN GIAO TRONG H THNG 3G WCDMA
Mc Lc:
1.Tng quan v chuyn giao trong mng di ng
* Gii thiu khi qut v chuyn giao
*Cc kiu chuyn giaotrong h thng 3G WCDMA
*Cc mc ch v cch thc khi to chuyn giao
*Cc th tc c bn trong mt qu trnh chuyn giao
2. Chuyn giao mm (SHO)
2.1 Chuyn giao mm (SHO) v chuyn giao mm hn
2.2 Nguyn l ca chuyn giao mm
2.3 Thut ton chuyn giao mm
2.4 c im ca chuyn giao mm.
3. Kt Lun*****************************************************************
Cc thnh vin c phn cng nhim v nh sau:
+ ng Th Giang: Tng quan v chuyn giao trong mng di ng
+ Nguyn Th Thanh Mai: Chuyn giao mm(2-1 n 2.3)
+on Xun Qunh: Mc 2.4(c im ca chuyn giao mm) v 3-
Kt lun.
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Phn B: cng chi tit
1. Tng quan v chuyn giao trong mng di ng
* Gii thiu khi qut v chuyn giao
Phn tch v d:
Trong mng t bo, mi mt trm pht sng BTS c mt vng ph
gii hn (vi km). Khi bn ngi trn t/ xe bus v in thoi cho ai , th
chc chn bn khng th ni kt vi cng 1 trm BTS c. Khi bn i rakhi vng ph sng ca mt trm BTS A v i vo vng ph ca mt trm
BTS B, lc bn s kt ni vi trm B. D nhin l cuc gi vn din ra
bnh thng.
Nhn xt:Qu trnh chuyn i kt ni t mt trm pht sng nysang mt trm pht sng khc c gi chung l chuyn giao(handover).
Handover l g?
- Chuyn giao l mt phn cn thit cho vic x l sdi ng
ca ngi s dng u cui.
- N m bo tnh lin tc ca cc dch v v tuyn khi ngi
s dng di ng di chuyn t qua ranh gii cc t bo.
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* Cc kiu chuyn giaotrong h thng 3G WCDMA
- Chuyn giao ni h thng: xy ra bn trong mt h thng
WCDMA. C th c cc loi sau
. Chuyn giao ni h thng gia cc thuc cng mt tn ssng mang WCDMA
. Chuyn giao gia cc tn s, gia cc hot ng trn cc
tn s WCDMA khc nhau
- Chuyn giao gia cc h thng: gia cc thuc 2 cng ngh
truy cp v tuyn khc nhau, hay cc ch truy cp v truyn khc
nhau. Trng hp thng xuyn xy ra nht i vi kiu th nht l
chuyn giao gia cc h thng WCDMA v GSM. Tuy nhin cng c
th gia cc h thng WCDMA vi cc h thng CDMA khc (
CDMA 2000 1x)
* Cc mc ch v cch thc khi to chuyn giao :
+ Khi to : t 3 cch khc nhau l my di ng khi xng,
mng khi xngv my di ng h tr.
Hnh1.1 Cc vin cnh ca cc kiu chuyn giao khc nhau+ Mc ch
m bo tnh lin tc ca cc dch v v tuyn khi
ngi s dng di ng di chuyn qua ranh gii ca cc t bo.
Gicho QoS m bo mc yu cu.
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Lm gim nh mc nhiu trong ton b h thng bng
cch gicho my di ng c kt ni vi BS tt nht.
Roaming gia cc mng khc nhau
Cn bng ti. S khi xng cho mt qu trnh chuyn giao c th bt
ngun t cht lng dch v ca lin kt (UL hoc DL), sthay i
ca dch v, sthay i tc , cc l do lu lng hoc s can thit
vn hnh v bo dng.
*Cc th tcc bn trong mt qu trnh chuyn giaoChuyn giao ngang (horizontal HO) trong mng t bo c th phn
ra thnh 3 bc chnh nh sau:
+ HO measurement (o c/theo di cht lng ng
truyn radio)
+ HO decision (ra quyt nh chuyn giao).+ HO Execution (tin hnh chuyn giao)
C th tng bc nh sau:
Bc 1: Trong sut qu trnh lin lc, thit b cm tay (gi
nm na l UE (user equipment)) s lun o nng lng thu
c tBTS ang ni kt v ca c cc BTS xung quanh
n. UE thng xuyn gi bo co v tnh hnh o c ny
v trm pht sng (Node B trong UMTS/BTS trong GSM) v
thit b qun l radio (RNC trong UMTS/BSC trong GSM).
Bc 2: Nu cht lng ng truyn t trm pht hin ti
kt ni n UE b gim mnh di mt mc no , thmng s quyt nh tin hnh HO. Mng s chn ra mt ci
BTS ln cn m cho cht lng ng truyn tt nht
UE ni kt vo.
Bc 3 UE thit lp ni kt vi trm mi v ti nguyn dnh
ring cho UE trm c s c gii phng. Ty theo
soft/hard HO m cc qu trnh ny sc thc hin mt
cch khc nhau.
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2 Chuyn giaomm (SHO)
2.1 Chuyn giao mm (SHO) v chuyn giao mm hn.
+
C
h
u
y
n
g
i
a
o
m
m
+ Ch c trong cng ngh CDMA.
+ So vi chuyn giao cng thng thng, chuyn
giao mm c mt s u im.
+ Tuy nhin, n cng c mt s cc hn ch v s
phc tp v vic tiu th ti nguyn tng ln.
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So snh gia chuyn giao cng v chuyn giao mmChuyn giao mm(SHO)v chuyngiao mm hn.
Chuyn giao cng truynthng(HHO)
- Mt quyt nh c iu kin c
thc hin quyt nh c
chuyn giao hay l khng. Tu
thuc vo nhng thay i ca
cng tn hiu knh hoa tiu
t 2 hoc nhiu trm gc tham
gia vo qu trnh, mt quyt nh
tt nht cui cng s c thc
hin truyn thng vi mt v
ch mt trm gc m thi. V iu
ny thng xy ra sau khi
chc chn rng tn hiu n t
trm gc c chn mnh hntn hiu n t cc trm gc
khc.
- xy ra trong mt tn s sng
mang v trong cng mt h
thng, ko di trong mt chu
k thi gian
- UE lun duy tr t nht mt ngv tuyn ni n UTRAN
- Mt quyt nh xc
nh c thc hin
chuyn giao hay
khng chuyn giao v
trm di ng ch
truyn thng vi mt
trm gc ti thi gian
.
- xy ra ti mt im thi gian
- Tt ccc ng truyn v
tuyn c ca mt UE c
gii phng trc khi thit lp
cc ng truyn v tuyn
mi.
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2.2 Nguyn l ca chuyn giaomm
- Trong sut qu trnh chuyn giao mm, mt my di ng ng
thi giao tip vi c 2 hoc nhiu cell ( i vi c 2 loi chuyn giao
mm) thuc v cc trm gc khc nhauca cng mt b iu khin
mng v tuyn (intra-RNC) hoc cc b iu khin mng v tuyn
khc nhau (inter-RNC).
- Trn ng xung (DL), my di ng nhn cc tn hiu
kt hp vi t s ln nht. - Trn ng ln (UL), knh m di ng
c tch sng bi c 2 BS (i vi c 2 kiu SHO), v c nh
tuyn n b iu khin v tuyn cho s kt hp la chn.
- Hai vng iu khin cng sut tch cc u tham gia vochuyn giao mm: mi vng cho mt BS.
- Trong trng hp chuyn giao mm hn, mt my di ng
c iu khin bi t nht 2 sector trong cng mt BS, RNC
khng quan tm v ch c mt vng iu khin cng sut hot
ng.
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- Chuyn giao mm v chuyn giao mm hn ch c th xy
ra trong mttn s sng mang, do chng l cc qu trnh chuyn
giao trong cng tn s.
2.3 Thut ton chuyn giao mm
- Thut ton c mt tm nh hng ln n hiu sut ca qutrnh chuyn giao mm.
Hnh 2. Thut ton chuyn giao mm ca IS-95A
Trong hnh:
The Active set (Tp tch cc): l danh sch cc
Cell m hin ang kt ni vi trm di ng.
The Candidate set (Tp ng c): l danh sch
cc Cell m hin khng c s dng trong kt ni
chuyn giao mm, nhng cc gi tr Ec/I0 knh pilot ca
chng l mnh c b sung vo tp tch cc.
The neighbouring set ( Tp ln cn): l danh sch
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cc Cell m tram di ng o lng lin tc, nhng
cc gi tr Ec/I0 knh pilot ca chng khng
mnh b sung vo tp tch cc.
Trong IS-95A, ngng chuyn giao l mt gi tr
Ec/I0 cnh nhn c tknh hoa tiu. N rt
d thc hin, nhng li gp nhiu kh khn khi
phi i mt vi nhng thay i ti ng. Da trn
thut ton IS-95A, nhiu bin i ca thut ton
cdmaOne vi tnh nng ng hn ngng cnh
c xut cho h thng IS- 95B vcdma2000.
Trong WCDMA s dng cc thut ton phc tp hn, cminh ho nh trn hnhdi.
Hnh 3. Thut ton chuyn giao mm ca WCDMA
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M t thut ton chuyn giao mm WCDMA :
Lc u.Ch c 1 v 2 nm trong tp tch cc
+Ti s kin A. (Ec/I0)P-CPICH3 > (Ec/I0)P-
CPICH1 - (R1a-H1a/2)
+Ti s kin C. (Ec/I0)P-CPICH4 > (Ec/I0)P-
CPICH2 +H1c/2
+Ti s kin B. (Ec/I0)P-CPICH1 < (Ec/I0)P-
CPICH3- (R1b+H1b/2)
=>Nhn xt:So vi IS-95A, li ch ln nht ca gii
thut ny l s biu din tham s mt cch d dng, v nh
c cc gi tr ngng tng i nn khng yu cu bt k mt s
thay i tham s no i vi cc khu vc c nhiu cao v thp.
2.4 c im ca chuyn giao mm.
- u im ca chuyn giao mm:
+ Loi b hin tng ping pong v lm ng truyn dn lin tc,
khng gy khc.
+ Ngoi vic x l tnh di ng ca thu bao, chuyn giao mm cn
c s dng nh mt c ch gim nhiu.
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Hnh (a) : iu khin cng sut c s dng.
Hnh (b): iu khin cng sut v chuyn giao mm u c h tr.c im chnh ca chuyn giao mm:
- u im:
+ Gim hin tng ping pong
=> Gim tng ph v s lng ti trn mng bo hiu.
+Truyn dn lin tc, khng xy ra gin on sut trong qu trnh
chuyn giao mm.
+ Khng c s d tr tr, dn ti tr hon thp hn.
+ Gim nhiu hng ln, dn n: cht lng truynthng tt hn
cho mt s lng ngi dng nht nh ng thi tng s lng ngi
dng vi cng mt Qos yu cu.
+ Cc rng buc v thi gian trn mng t hn, gip cho xc sut chn
v rt cuc gi gim i.
* Nhn xt: li lin kt chuyn giao mm
- li phn tp v m: li ch phn tp nh Fading
chm v s st tngt ca cng tn hiu do cc
nguyn nhn chng hn nh s di chuyn ca MS vng
quanh mt gc.
- li phn tp vi m: li phn tp nh Fadingnhanh.
- Vic chia s ti ngxung: Mt MS khi chuyn giao
mm thu cng sutt nhiu Node-B, iu cho thy cng
sut pht ln nht n MS trong khichuyn giao mm X-way
c nhn vi h s X, ngha l vng ph c m rng.
- Nhc im:
Gim nhiu hng ln bng cch s dng SHO ( Soft Handover).
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Bn cnh nhng u im li th hn so vi chuyn giao cng th chuyn
giao mm vn c nhng nhc im nh:
+ S phc tp.
+ Cn phi b sung thm ngun ti nguyn mng hng xung (tinguyn v m cng sut).
3. Kt Lun:
- Cc u cui di ng cho php thu bao truy xut cc dch v trong khi
ang dichuyn, iu ny c bit thc yspht trin 1 cch nhanh
chng cangnh cng nghip mng di ng, v thay i n t mt cng
ngh mi thnh mt ngnh cng nghip ln trong vng t hn hai thp k.
- Chuyn giao l mtchc nng thit yu i ph vi tnh di ng ca
cc thu bao di ng. So vi chuyn giao cng truyn thng c s dng
trong mng di ng GSM, th chuyn giao mm s dng trong IS-95 v
c xut cho mng 3G c hiu sut tt hn trn c hai cp ng
dn v h thng.
- Trong hu ht cc phn tch trc y v chuyn giao mm u tp
trung vo hng ln. Tuy nhin, trong cc mng di ng tng lai th
hng xung li cc kquan trng i vi dung lng h thng bi tnhbt
i xng ca cc dch v mi, chng hn nh lu lng Internet
THE_END.