N TT NGHIPLI CAM OANTixincamoanrngylcngtrnhnghincucati,cshtrt
Gio vinhng dn l TS. Lm Hng Thch. Cc nidungnghin cu v kt qu trong
tinyl trungthc vcha tng c aicng b trong bt c cng trnh nghincu no
trc y. Mi tham kho dng trong lun vn u c trch dn r rng tn tc gi, tn
cng trnh, thi gian, a im cng b.Mi sao chp khng hp l, vi phm quy ch
o to, hay gian tr, ti xin chu hon ton trch nhim.Hi An, ngy 05thng
05 nm 2012Sinh vin thc hin Nguyn Th Thu HngGVHD: Lm Hng Thch SVTH:
Nguyn Th Thu Hng i N TT NGHIPLI CM N hon thnh n tt nghip ny, li u
tin em xin chn thnh cm n cc thy gio, c gio KhoaKhoa hcvcng nghTrng
ihc PhanChu Trinh, nhng ngi dy d, trang b cho em nhng kn thc b ch
trong bn nm hc va qua.Em xin by t lng bit n su sc nht ti thy gio Lm
Hng Thch, ngi tn tnh hng dn, ch bo em trong sut thi gian thc tp v
lm n.
Em xin chn thnh cm n !Hi An, ngy 10 thng 04 nm 2012
Sinh vin Nguyn Th Thu HngGVHD: Lm Hng Thch SVTH: Nguyn Th Thu
Hng ii N TT NGHIP MC LC Nguyn Th Thu Hng ii MC LC iiiDANH MC HNH V
xii Nguyn Th Thu Hng ii xii MC LC iii xii Nguyn Th Thu Hng ii iii
xii MC LC iii iii xiiDANH MC HNH V viii iii xiiLI M U 1 iii xiiChng
1 S PHT TRIN CA H THNG THNG TIN DI NG VIT NAM 1 iii xii1.1 Gii thiu
v cc h thng thng tin di ng1 iii xii1.2 Cng ngh thng tin di ng tng
lai 6 iii xiiHnh 1.1Nng lc ca cc h thng3G m rng. 8 iii xiiHnh
1.2Mng tng lai thng nht, bao gm nhiuh thngtruy nhp an xen nhau 9
iii xiiHnh 1.3Nhng vn k thut lin quan n cng ngh v tuyn 11 iii
xiiHnh 1.4Cu hnh h thng 4G 15 iii xiiHnh 1.5 Lin lc thng qua cc kt
ni multi-hop 16 iii xiiChng 2M HA KNH TRONGTHNG TIN DI NG 20 iii
xii2.1 Qu trnh m ha v nguyn l 20 iii xiiGVHD: Lm Hng Thch SVTH:
Nguyn Th Thu Hng iii N TT NGHIPHnh 2.1Qu trnh m ha trong h
thngtruynthngs 21 iii xii2.2 Vai tr ca m ha22 iii xii2.3 Cc phng
php m ha knh trong h thng 3G 23 iii xiiHnh 2.2M ha khi 24 iii
xiiiHnh 2.3B m c tnh h thngv khngh thng 25 iii xiiiHnh 2.4B m ha
xon t l 1/3 27 iv xiiiHnh 2.5 B m ha Turbo 29 iv xiiiHnh 2.6 B gii
m Turbo 30 iv xiiiHnh 2.7S khi ca mt h thng MIMO 37 iv xiii2.6Kt
lun chng 39 iv xiii3.1 Phng php m ha khng gian - thi gian40 iv
xiiiHnh 3.1Mt m hnh h thng bng tn gc 41 iv xiiiHnh 3.2 S m li 47 iv
xiiiHnh 3.3B m li k=1, K=3 v n=2 47 iv xiiiHnh 3.4Li m v s trng thi
vi k=1, K=3 v n=2 48 iv xiiiHnh 3.5S khi ca b m ha STTC 50 iv
xiiiHnh 3.6ng bin gia tiu chun TSC v tiu chun vt 54 iv xiiiHnh 3.7B
m ha STTC vi 4-PSK 55 iv xiiiHnh 3.8c tnh FER ca h thng BPSK
Alamouti vi 1 v 2 anten thu trn knh fading Rayleigh chm 58 iv
xiiiHnh 3.9c tnh FER ca h thng QPSK Alamouti vi 1 v 2 anten thu trn
knh fading Rayleigh chm 59 iv xiiiGVHD: Lm Hng Thch SVTH: Nguyn Th
Thu Hng iv N TT NGHIPHnh 3.11S khi ca b m ha ST Alamouti 62 iv
xiiiHnh 3.14c tnh BER ca h thng BPSK Alamouti vi 2 v 1 anten thu
trn knh fading Rayleigh chm 70 iv xiiiHnh 3.15c tnh BER ca h thng
BPSK Alamouti vi 2 v 2 anten thu trn knh fading Rayleigh chm 73 iv
xivHnh 3.17c tnh m STBC, STBC+TCM, STTC s dng m 4 v 8 trng 75 iv
xivthi vi 2 anten pht, 3 anten thu (IEEE, 2001) 75 v xivDANH MC HNH
V viii xivLI M U 1 xivChng 1 S PHT TRIN CA H THNG THNG TIN DI NG
VIT NAM 1 xiv1.1 Gii thiu v cc h thng thng tin di ng1 xiv1.2 Cng
ngh thng tin di ng tng lai 6 xivHnh 1.1Nng lc ca cc h thng3G m rng.
8 xivHnh 1.2Mng tng lai thng nht, bao gm nhiuh thngtruy nhp an xen
nhau 9 xivHnh 1.3Nhng vn k thut lin quan n cng ngh v tuyn 11 xivHnh
1.4Cu hnh h thng 4G 15 xivHnh 1.5 Lin lc thng qua cc kt ni
multi-hop 16 xivChng 2M HA KNH TRONGTHNG TIN DI NG 20 xiv2.1 Qu
trnh m ha v nguyn l 20 xivHnh 2.1Qu trnh m ha trong h
thngtruynthngs 21 xiv2.2 Vai tr ca m ha22 xivGVHD: Lm Hng Thch
SVTH: Nguyn Th Thu Hng v N TT NGHIP2.3 Cc phng php m ha knh trong h
thng 3G 23 xivHnh 2.2M ha khi 24 xivHnh 2.3B m c tnh h thngv khngh
thng 25 xivHnh 2.4B m ha xon t l 1/3 27 xvHnh 2.5 B m ha Turbo 29
xvHnh 2.6 B gii m Turbo 30 xvHnh 2.7S khi ca mt h thng MIMO 37
xv2.6Kt lun chng 39 xv3.1 Phng php m ha khng gian - thi gian40
xvHnh 3.1Mt m hnh h thng bng tn gc 41 xvHnh 3.2 S m li 47 xvHnh
3.3B m li k=1, K=3 v n=2 47 xvHnh 3.4Li m v s trng thi vi k=1, K=3
v n=2 48 xvHnh 3.5S khi ca b m ha STTC 50 xvHnh 3.6ng bin gia tiu
chun TSC v tiu chun vt 54 xvHnh 3.7B m ha STTC vi 4-PSK 55 xvHnh
3.8c tnh FER ca h thng BPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh chm 58 xvHnh 3.9c tnh FER ca h thng QPSK Alamouti
vi 1 v 2 anten thu trn knh fading Rayleigh chm 59 xvHnh 3.11S khi
ca b m ha ST Alamouti 62 xvHnh 3.14c tnh BER ca h thng BPSK
Alamouti vi 2 v 1 anten thu trn knh fading Rayleigh chm 70 xvGVHD:
Lm Hng Thch SVTH: Nguyn Th Thu Hng vi N TT NGHIPHnh 3.15c tnh BER
ca h thng BPSK Alamouti vi 2 v 2 anten thu trn knh fading Rayleigh
chm 73 xvHnh 3.17c tnh m STBC, STBC+TCM, STTC s dng m 4 v 8 trng 75
xvthi vi 2 anten pht, 3 anten thu (IEEE, 2001) 75 xviLI M U 1Chng 1
S PHT TRIN CA H THNG THNG TIN DI NG VIT NAM 11.1 Gii thiu v cc h
thng thng tin di ng11.2 Cng ngh thng tin di ng tng lai 6Hnh 1.1Nng
lc ca cc h thng3G m rng. 8Hnh 1.2Mng tng lai thng nht, bao gm nhiuh
thngtruy nhp an xen nhau 9Hnh 1.3Nhng vn k thut lin quan n cng ngh
v tuyn 11Hnh 1.4Cu hnh h thng 4G 15Hnh 1.5 Lin lc thng qua cc kt ni
multi-hop 16Chng 2M HA KNH TRONGTHNG TIN DI NG 202.1 Qu trnh m ha v
nguyn l 20Hnh 2.1Qu trnh m ha trong h thngtruynthngs 212.2 Vai tr
ca m ha222.3 Cc phng php m ha knh trong h thng 3G 23Hnh 2.2M ha khi
24Hnh 2.3B m c tnh h thngv khngh thng 25Hnh 2.4B m ha xon t l 1/3
27GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng vii N TT NGHIPHnh 2.5 B
m ha Turbo 29Hnh 2.6 B gii m Turbo 30Hnh 2.7S khi ca mt h thng MIMO
372.6Kt lun chng 393.1 Phng php m ha khng gian - thi gian40Hnh
3.1Mt m hnh h thng bng tn gc 41Hnh 3.2 S m li 47Hnh 3.3B m li k=1,
K=3 v n=2 47Hnh 3.4Li m v s trng thi vi k=1, K=3 v n=2 48Hnh 3.5S
khi ca b m ha STTC 50Hnh 3.6ng bin gia tiu chun TSC v tiu chun vt
54Hnh 3.7B m ha STTC vi 4-PSK 55Hnh 3.8c tnh FER ca h thng BPSK
Alamouti vi 1 v 2 anten thu trn knh fading Rayleigh chm 58Hnh 3.9c
tnh FER ca h thng QPSK Alamouti vi 1 v 2 anten thu trn knh fading
Rayleigh chm 59Hnh 3.11S khi ca b m ha ST Alamouti 62Hnh 3.14c tnh
BER ca h thng BPSK Alamouti vi 2 v 1 anten thu trn knh fading
Rayleigh chm 70Hnh 3.15c tnh BER ca h thng BPSK Alamouti vi 2 v 2
anten thu trn knh fading Rayleigh chm 73Hnh 3.17c tnh m STBC,
STBC+TCM, STTC s dng m 4 v 8 trng 75thi vi 2 anten pht, 3 anten thu
(IEEE, 2001) 75GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng viii N TT
NGHIPDANH MC T VIT TT3G Third generation Th h th 34G Fourth
generation Th h th 4AARM Adaptive multi rate Tc a thch ngARQ
Automatic repeat request Yu cu lp li t ngAWGN Additive white
Gaussian noise Tp m Gaussian trng cngBBER Bit error rate T l li
bitBPSK Binary phase shift keying Kho dch pha nh phnCCDMA Code
division multiple access a truy cp phn chia theo mCRC Cyclic
redundancy check Kim tra d chu trnhCSI Channel state information
Thng tin trng thi knhDDAB Digital audio broadcastingPht thanh sDPSK
Differential phase shift keying Kho dch pha vi saiDVB Digital video
broadcasting Truyn hnh sEEXIT Extrinsic information transfer Chuyn
giao thng tin ngoiFFEC Forward error correction Sa li trcFER Frame
error rate T l li khungGGPRS General packet radio services Dch v v
tuyn gi chungHHSPA High speed packet access a truy cp gi tc
caoIIEEE Institute of Electrical and Electronic EngineersVin nghin
cu k thut in v in ti.i.d Independent identicallyS phn b c lp
nhauGVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng ix N TT
NGHIPdistributedLLLR Log-likelihood ratio T l on cc iLOS
Line-of-sight Nhn thngLTE Long term evolution S pht trin trong tng
laiLST Layered space-time Tng khng gian thi gianMMAP Max a
posteriori Gi tr cui ln nhtMC-CDMA MultiCarrier Code Division
Multiple Accessa truy nhp phn chia theo m iu ch a sng mang MIMO
Multiple-input Multiple-output Nhiu anten ra, nhiu anten voMLSE
Maximum likelihood sequence estimatorKh nng ging nhtMMS Multimedia
messages service Dch v tin nhn a phng tinMMSE Minimum mean square
error Li bnh phng trung bnh nh nhtMMS Maximal ratio combining Kt hp
t l ti aNNLOS Non line of sight KhutOOFDMA Othogonal frequency
division multiple accessa truy nhp phn chia tn s trc giaoPPCBC
Parallel concatenated block coderM khi kt ni song songPCCC Parallel
concatenated convolutional coderM xon kt ni song songPDF
Probability density function Hm mt xc sutPSF Phase shift keying iu
ch kho dch phaQQAM Quadrature amplitude modulationiu ch bin cu
phngQPSK Quadrature phase-shift keying Kho dch pha cu phngQoS
Quality of service Cht lng dch vGVHD: Lm Hng Thch SVTH: Nguyn Th
Thu Hng x N TT NGHIPSSER Symbol error rate T l li h thngSCBC Serial
concatenated block coder M khi theo th t ni tipSCCC Serial
concatenated convolutional coderM xon theo th t ni tipSNR Signal to
noise ratio T s tn hiu trn tp mS/P Serial-to-parallel Ni tip/song
songST Space-time Khng gian thi gianSTC Space-time code M khng gian
thi gianSCBC Space-time block codes M khi khng gian thi gianSTTC
Space-time trellis code M ho li khng gian thi gianSVD Singular
value decomposition Phn tch gi tr ringTTCM Trellis coded modulation
iu ch m trellisUUE User equipment Thit b ngi dungUMB Ultra Mobile
Broadband Di ng bng tn siu rngUMTS Universal mobile
telecommunication systemsH thng vin thng di ng ton cuUTRAN
Universal terrestrial radio access networkMng truy nhp v tuyn mt t
ton cuWWCDMA Wideband code division access a truy nhp phn chia theo
m bng rngGVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng xi N TT NGHIPDANH
MC HNH V Nguyn Th Thu Hng.............ii MC
LC.............................................................................................................iii
Nguyn Th Thu Hng ii.........iii MC LC
iii.........................................................................................................iiiDANH
MC HNH V
xii......................................................................................iii
Nguyn Th Thu Hng ii xii....iii MC LC iii
xii....................................................................................................iii
Nguyn Th Thu Hng ii iii xii iii MC LC iii iii
xii................................................................................................iiiDANH
MC HNH V viii iii
xii............................................................................iiiLI
M U 1 iii
xii..............................................................................................iiiChng
1 S PHT TRIN CA H THNG THNG TIN DI NG VIT NAM 1 iii
xii.............................................................................................................iii1.1
Gii thiu v cc h thng thng tin di ng1 iii
xii........................................iii1.2 Cng ngh thng tin
di ng tng lai 6 iii
xii..................................................iiiHnh 1.1Nng
lc ca cc h thng3G m rng. 8 iii
xii....................................iiiHnh 1.2Mng tng lai thng
nht, bao gm nhiuh thngtruy nhp an xen nhau 9 iii
xii.............................................................................................................iiiHnh
1.3Nhng vn k thut lin quan n cng ngh v tuyn 11 iii
xii........iiiHnh 1.4Cu hnh h thng 4G 15 iii
xii...............................................................iiiHnh
1.5 Lin lc thng qua cc kt ni multi-hop 16 iii
xii...................................iiiGVHD: Lm Hng Thch SVTH:
Nguyn Th Thu Hng xii N TT NGHIPChng 2M HA KNH TRONGTHNG TIN DI NG
20 iii xii.........iii2.1 Qu trnh m ha v nguyn l 20 iii
xii............................................................iiiHnh
2.1Qu trnh m ha trong h thngtruynthngs 21 iii
xii..................iv2.2 Vai tr ca m ha22 iii
xii..............................................................................iv2.3
Cc phng php m ha knh trong h thng 3G 23 iii
xii.............................ivHnh 2.2M ha khi 24 iii
xiii..............................................................................ivHnh
2.3B m c tnh h thngv khngh thng 25 iii
xiii.............................ivHnh 2.4B m ha xon t l 1/3 27 iv
xiii...........................................................ivHnh
2.5 B m ha Turbo 29 iv
xiii......................................................................ivHnh
2.6 B gii m Turbo 30 iv
xiii......................................................................ivHnh
2.7S khi ca mt h thng MIMO 37 iv
xiii.........................................iv2.6Kt lun chng 39 iv
xiii.................................................................................iv3.1
Phng php m ha khng gian - thi gian40 iv
xiii.....................................ivHnh 3.1Mt m hnh h thng
bng tn gc 41 iv xiii..........................................ivHnh
3.2 S m li 47 iv
xiii..............................................................................ivHnh
3.3B m li k=1, K=3 v n=2 47 iv
xiii......................................................ivHnh
3.4Li m v s trng thi vi k=1, K=3 v n=2 48 iv
xiii.....................ivHnh 3.5S khi ca b m ha STTC 50 iv
xiii...............................................ivHnh 3.6ng bin
gia tiu chun TSC v tiu chun vt 54 iv xiii.................ivHnh
3.7B m ha STTC vi 4-PSK 55 iv
xiii......................................................ivHnh
3.8c tnh FER ca h thng BPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh chm 58 iv
xiii................................................................................ivGVHD:
Lm Hng Thch SVTH: Nguyn Th Thu Hng xiii N TT NGHIPHnh 3.9c tnh FER
ca h thng QPSK Alamouti vi 1 v 2 anten thu trn knh fading Rayleigh
chm 59 iv
xiii................................................................................ivHnh
3.11S khi ca b m ha ST Alamouti 62 iv
xiii.................................vHnh 3.14c tnh BER ca h thng
BPSK Alamouti vi 2 v 1 anten thu trn knh fading Rayleigh chm 70 iv
xiii........................................................................vHnh
3.15c tnh BER ca h thng BPSK Alamouti vi 2 v 2 anten thu trn knh
fading Rayleigh chm 73 iv
xiv.........................................................................vHnh
3.17c tnh m STBC, STBC+TCM, STTC s dng m 4 v 8 trng 75 iv
xiv...................................................................................................................................vthi
vi 2 anten pht, 3 anten thu (IEEE, 2001) 75 v
xiv..........................................vDANH MC HNH V viii
xiv.................................................................................vLI
M U 1
xiv...................................................................................................vChng
1 S PHT TRIN CA H THNG THNG TIN DI NG VIT NAM 1
xiv..................................................................................................................v1.1
Gii thiu v cc h thng thng tin di ng1
xiv.............................................v1.2 Cng ngh thng
tin di ng tng lai 6
xiv.......................................................vHnh
1.1Nng lc ca cc h thng3G m rng. 8
xiv.........................................vHnh 1.2Mng tng lai
thng nht, bao gm nhiuh thngtruy nhp an xen nhau 9
xiv..................................................................................................................vHnh
1.3Nhng vn k thut lin quan n cng ngh v tuyn 11 xiv.............vHnh
1.4Cu hnh h thng 4G 15
xiv.....................................................................vHnh
1.5 Lin lc thng qua cc kt ni multi-hop 16
xiv........................................vChng 2M HA KNH
TRONGTHNG TIN DI NG 20 xiv..............vGVHD: Lm Hng Thch SVTH:
Nguyn Th Thu Hng xiv N TT NGHIP2.1 Qu trnh m ha v nguyn l 20
xiv.................................................................vHnh
2.1Qu trnh m ha trong h thngtruynthngs 21
xiv......................v2.2 Vai tr ca m ha22
xiv...................................................................................v2.3
Cc phng php m ha knh trong h thng 3G 23
xiv.................................viHnh 2.2M ha khi 24
xiv...................................................................................viHnh
2.3B m c tnh h thngv khngh thng 25
xiv.................................viHnh 2.4B m ha xon t l 1/3 27
xv.................................................................viHnh
2.5 B m ha Turbo 29
xv...........................................................................viHnh
2.6 B gii m Turbo 30
xv...........................................................................viHnh
2.7S khi ca mt h thng MIMO 37
xv..............................................vi2.6Kt lun chng 39
xv.......................................................................................vi3.1
Phng php m ha khng gian - thi gian40
xv..........................................viHnh 3.1Mt m hnh h
thng bng tn gc 41
xv...............................................viHnh 3.2 S m li
47
xv...................................................................................viHnh
3.3B m li k=1, K=3 v n=2 47
xv...........................................................viHnh
3.4Li m v s trng thi vi k=1, K=3 v n=2 48
xv..........................viHnh 3.5S khi ca b m ha STTC 50
xv....................................................viHnh 3.6ng
bin gia tiu chun TSC v tiu chun vt 54
xv.......................viHnh 3.7B m ha STTC vi 4-PSK 55
xv............................................................viHnh
3.8c tnh FER ca h thng BPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh chm 58
xv.....................................................................................viGVHD:
Lm Hng Thch SVTH: Nguyn Th Thu Hng xv N TT NGHIPHnh 3.9c tnh FER ca
h thng QPSK Alamouti vi 1 v 2 anten thu trn knh fading Rayleigh chm
59
xv.....................................................................................viHnh
3.11S khi ca b m ha ST Alamouti 62
xv......................................viHnh 3.14c tnh BER ca h
thng BPSK Alamouti vi 2 v 1 anten thu trn knh fading Rayleigh chm
70
xv............................................................................viHnh
3.15c tnh BER ca h thng BPSK Alamouti vi 2 v 2 anten thu trn knh
fading Rayleigh chm 73
xv...........................................................................viiHnh
3.17c tnh m STBC, STBC+TCM, STTC s dng m 4 v 8 trng 75 xvviithi vi
2 anten pht, 3 anten thu (IEEE, 2001) 75
xvi...........................................viiLI M U
1.......................................................................................................viiChng
1 S PHT TRIN CA H THNG THNG TIN DI NG VIT NAM
1.....................................................................................................................vii1.1
Gii thiu v cc h thng thng tin di
ng1.................................................vii1.2 Cng ngh
thng tin di ng tng lai
6...........................................................viiHnh
1.1Nng lc ca cc h thng3G m rng.
8.............................................viiHnh 1.2Mng tng lai
thng nht, bao gm nhiuh thngtruy nhp an xen nhau
9......................................................................................................................viiHnh
1.3Nhng vn k thut lin quan n cng ngh v tuyn
11................viiHnh 1.4Cu hnh h thng 4G
15........................................................................viiHnh
1.5 Lin lc thng qua cc kt ni multi-hop
16............................................viiChng 2M HA KNH
TRONGTHNG TIN DI NG 20..................vii2.1 Qu trnh m ha v nguyn
l
20.....................................................................viiHnh
2.1Qu trnh m ha trong h thngtruynthngs
21..........................viiGVHD: Lm Hng Thch SVTH: Nguyn Th Thu
Hng xvi N TT NGHIP2.2 Vai tr ca m
ha22.......................................................................................vii2.3
Cc phng php m ha knh trong h thng 3G
23......................................viiHnh 2.2M ha khi
24........................................................................................viiHnh
2.3B m c tnh h thngv khngh thng
25......................................viiHnh 2.4B m ha xon t l
1/3
27....................................................................viiHnh
2.5 B m ha Turbo
29..............................................................................viiiHnh
2.6 B gii m Turbo
30..............................................................................viiiHnh
2.7S khi ca mt h thng MIMO
37.................................................viii2.6Kt lun
chng
39.........................................................................................viii3.1
Phng php m ha khng gian - thi
gian40.............................................viiiHnh 3.1Mt m
hnh h thng bng tn gc
41.................................................viiiHnh 3.2 S m
li
47.....................................................................................viiiHnh
3.3B m li k=1, K=3 v n=2
47.............................................................viiiHnh
3.4Li m v s trng thi vi k=1, K=3 v n=2
48.............................viiiHnh 3.5S khi ca b m ha STTC
50.......................................................viiiHnh
3.6ng bin gia tiu chun TSC v tiu chun vt
54.........................viiiHnh 3.7B m ha STTC vi 4-PSK
55..............................................................viiiHnh
3.8c tnh FER ca h thng BPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh chm
58........................................................................................viiiHnh
3.9c tnh FER ca h thng QPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh chm
59........................................................................................viiiHnh
3.11S khi ca b m ha ST Alamouti
62........................................viiiGVHD: Lm Hng Thch
SVTH: Nguyn Th Thu Hng xvii N TT NGHIPHnh 3.14c tnh BER ca h thng
BPSK Alamouti vi 2 v 1 anten thu trn knh fading Rayleigh chm
70...............................................................................viiiHnh
3.15c tnh BER ca h thng BPSK Alamouti vi 2 v 2 anten thu trn knh
fading Rayleigh chm
73...............................................................................viiiHnh
3.17c tnh m STBC, STBC+TCM, STTC s dng m 4 v 8 trng 75. viiithi vi
2 anten pht, 3 anten thu (IEEE, 2001)
75...............................................viiiDANH MC HNH
V..........................................................................................xii
LI M
U............................................................................................................1
Chng 1 S PHT TRIN CA H THNG THNG TIN DI NG VIT
NAM..........................................................................................................................1
1.1 Gii thiu v cc h thng thng tin di ng
......................................................1 1.2 Cng ngh
thng tin di ng tng
lai................................................................6
Hnh 1.1Nng lc ca cc h thng3G m
rng..................................................8 Hnh 1.2Mng
tng lai thng nht, bao gm nhiuh thngtruy nhp an xen
nhau..........................................................................................................................9
Hnh 1.3Nhng vn k thut lin quan n cng ngh v tuyn
.....................11 Hnh 1.4Cu hnh h thng 4G
.............................................................................15
Hnh 1.5 Lin lc thng qua cc kt ni multi-hop
.................................................16 Chng 2M HA KNH
TRONGTHNG TIN DI NG .......................20 2.1 Qu trnh m ha v
nguyn l
.........................................................................20
Hnh 2.1Qu trnh m ha trong h thngtruynthngs
...............................21 2.2 Vai tr ca m
ha...........................................................................................22
2.3 Cc phng php m ha knh trong h thng
3G..........................................23 GVHD: Lm Hng Thch
SVTH: Nguyn Th Thu Hng xviii N TT NGHIPHnh 2.2M ha
khi............................................................................................24
Hnh 2.3B m c tnh h thngv khngh thng
...........................................25 Hnh 2.4B m ha xon t l
1/3
.........................................................................27
Hnh 2.5 B m ha
Turbo....................................................................................29
Hnh 2.6 B gii m
Turbo....................................................................................30
Hnh 2.7S khi ca mt h thng MIMO
.......................................................37 2.6Kt lun
chng
...............................................................................................39
3.1 Phng php m ha khng gian - thi gian
...................................................40 Hnh 3.1Mt m
hnh h thng bng tn gc
.......................................................41 Hnh 3.2 S
m li
...........................................................................................47
Hnh 3.3B m li k=1, K=3 v n=2
...................................................................47
Hnh 3.4Li m v s trng thi vi k=1, K=3 v n=2
...................................48 Hnh 3.5S khi ca b m ha STTC
.............................................................50 Hnh
3.6ng bin gia tiu chun TSC v tiu chun vt
...............................54 Hnh 3.7B m ha STTC vi
4-PSK....................................................................55
Hnh 3.8c tnh FER ca h thng BPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh
chm..............................................................................................58
Hnh 3.9c tnh FER ca h thng QPSK Alamouti vi 1 v 2 anten thu trn knh
fading Rayleigh
chm..............................................................................................59
Hnh 3.11S khi ca b m ha ST
Alamouti..............................................62 Hnh 3.14c
tnh BER ca h thng BPSK Alamouti vi 2 v 1 anten thu trn knh fading
Rayleigh chm
.....................................................................................70
GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng xix N TT NGHIPHnh 3.15c
tnh BER ca h thng BPSK Alamouti vi 2 v 2 anten thu trn knh fading
Rayleigh chm
.....................................................................................73
Hnh 3.17c tnh m STBC, STBC+TCM, STTC s dng m 4 v 8 trng....... 75
thi vi 2 anten pht, 3 anten thu (IEEE, 2001)
.....................................................75 GVHD: Lm
Hng Thch SVTH: Nguyn Th Thu Hng xx N TT NGHIPLI M U1.Tnh cp thit ca
ti: Cc h thng thng tin di ng ang bng n c trn th gii v c Vit Nam.Trc
yu cu ngy cng cao ca ngi s dng thng tin di ng v cht lng v tnh a dng
ca dch v v c bit l cc dch v truyn d liu tc cao v a phng tin,vic
nghin cu, ng dng cc cng ngh v k thut tin tin p ng nhu cu ny lun l
mt i hi cp thit. Trc s pht trin v cng mnh m ca cc dch v s liu, trc
xu hng tch hp v IP ho t ra cc yu cu mi i vi cng nghip Vin Thng di
ng. Mng thng tin di ng th h ba ra i khc phc c cc nhc im ca cc mng
thng tin di ng th h trc . Tuy nhin, mng di ng ny cng c mt s nhc im
nh: Tc truyn d liu ln nht l 2Mbps, vn cha p ng c yu cu ngy cng cao
ca ngi dng, kh nng p ng cc dch v thi gian thc nh hi ngh truyn hnh l
cha cao, rt kh trong vic download cc file d liu ln,cha p ng c cc yu
cu ca ngi s dng.Trong bi cnh ngi ta chuyn hng sang nghin cu h thng
thng tin di ng mi c tn gi l 4G. Nghin cu v m ho knh l ti quan trng
v c ngha nht l trong thi k cc h thng vin thng ang tin n 4G. S ra i
ca h thng ny m ra kh nng tch hp tt c cc dch v, cung cp bng thng
rng, dung lng ln, truyn dn d liu tc cao, cung cp cho ngi s dng nhng
hnh nh video mu cht lng cao, cc tr chi ho 3D linh hot, cc dich v m
thanh s. Vic pht trin cng ngh giao thc u cui dung lng ln, cc dich v
gi d liu tc cao, cng ngh da trn nn tng phn mm cng cng mang n cc
chng trnh ngdngdownload,cngnghtruynhpvtuynamode,vcngnghmho media
cht lng cao trn nn cc mng di ng.GVHD: Lm Hng Thch SVTH: Nguyn Th
Thu Hng 1 N TT NGHIP2.Tnh hnh nghin cu: Hin nay Viettel a vo s dng
GPRS p ng nhu cu s dng cc dch v d liu ngy cng cao ca cc thu bao. Cc
dch v ch yu ca GPRS nh: WAP, truy nhp Internet c hai phng thc l
truy nhp gin tip v truy nhp trc tip, dch v nhn tin a phng tin,
video, xem cc on phim ti v, xem video trc tuyn. Ngoi ra cn c dch v
thng mi in t di ng, dch v ngn hng, qung co trn in thoi di ngdo gi
cc cn cao nn cc loi bao c thu nhp trung bnh v cao.3.Mc ch nghin
cu:Mc ch ca vic m ha knh l nhm chun b cc lung d liu sao cho vi nhng
li xy ra trong qu trnh truyn, cc my thu chc chn c th pht hin ra v
chun ha li c.Cng vic ny c thc hin hon ton thng qua qu trnh tnh ton
s liu d phn t cc lung d liu.Trong khi m ha ngun hng ti loi b cc d
liu d tha, th m ha knh lm tng tng dung lng d liu s truyn dn ng tin
cy hn v ci thin cht lng dch v .Cng ngh truyn thng di ng th h th 4 l
thc hin truyn thng v tuyn tc cao bng vi tc trong cc h thng truyn dn
si quang hin ti. Tuy cc h thng truyn thng di ng 4G c d on s c p dng
trong tng lai, nhng cc cng ngh tin thn v cc dch v ca n hin c gii
thiu. Vi vic tch hp Internet v cc ng dng a truyn thng trong cc h
thng vin thng th h 4G, yu cu v cc dch v truyn thng tc cao bng rng
ngy cng tng. Nhng v ph tn s sn c b gii hn nn t c tc d liu cao hn th
ch cn cch nghin cu v a ra nhng k thut x l tn hiu mi, hiu qu hn.4.
Nhim v nghin cu: Nhng nghin cu gn y v l thuyt thng tin cho thy rng
cc knh v tuyn c dung lng ln c th t c trong h thng MIMO
(multiple-input multiple-output). Knh MIMO c xy dng vi nhiu anten
phn t c hng pht ln hng thu. M khng gian-thi gian (space-time
coding) l mt tp hp cc k thut sp xp tn hiu thc t nhm t c mc ch l tin
n GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 2 N TT NGHIPgn gii hn
dung lng l thuyt ca cc knh MIMO. Nn tng ca m ha khng gian-thi gian
c t ra bi Tarokh, Seshadri v Calderbank vo nm 1998. s kt hp gia m
ha khng gian-thi gian v x l tn hiu MIMO sm tr thnh mt phm vi nghin
cu si ni nht trong truyn thng v tuyn. Lc ny, nhim v chnh ca nghin
cu l trit nhiu ti my thu.5. Phng php nghin cu: M ha khng gian thi
gian da vo mi quan h tng quan giacc tn hiu c phtc 2 min khng gianv
thi gian. Bng phng php ny, ta s t c ng thi li phn tp v li m ha, cng
c ngha l t c hiu qu ph tn cao. Cc nghin cu ban u tp trung vo vic
thit k mi quan h ph thuc khng gian-thi gian tn hiu pht vi mong mun
t c li phn tp v li m ha cao. Nhng gn y, cc nghin cu li chuyn sang
hng tn hiu ch c m ha trong min thi gian v c pht bi nhiu anten c
lp.6. Kt qu t c ca ti : l nn tng so snh vi cc m ha knh s dng trong
thng tin di ng 3G thy c nhng u im ni bt, tnh cp thit ca qu trnh hng
ti h thng thng tin di ng 4G, cho mt nn cng ngh k thut pht trin v
ang ngy mt i ln khng ngng.7. Ni dung ti: Ni dung ti bao gm 3 chng
:- Chng 1: S pht trin ca h thng thng tin di ng ca Vit Nam.- Chng 2:
M ha knh trong thng tin di ng- Chng 3: Cc phng php m ha knh xut s
dng trong 4G.
Xin chn thnh cm n !GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 3 N
TT NGHIPChng 1 S PHT TRIN CA H THNG THNG TIN DI NG VIT NAM1.1 Gii
thiu v cc h thng thng tin di ng 1.1.1Mng thng tin u tin 1GH thng
thng tin di ng 1G hay cn gi l s khi u gin n. 1G l ch vit tt ca cng
ngh in thoi khng dy th h u tin (1st Generation). N l h thng giao
tip thng tin qua kt ni tn hiu analog c gii thiu ln u tin vo nhng nm
u thp nin 80. N s dng cc ng-ten thu pht sng gn ngoi, kt ni theo tn
hiu analog ti cc trm thu pht sng v nhn tn hiu x l thoi thng qua cc
module gn trong my di ng.Mc d l th h mng di ng u tin vi tn s ch t
150MHz nhng mng 1G cng phn ra kh nhiu chun kt ni theo tng phn vng
ring trn th gii. Mt trong nhng cng ngh 1G ph bin l NMT (Nordic
Mobile Telephone) c s dng cc nc Bc u, Ty u v Nga. Cng c mt s cng
ngh khc nh AMPS (Advanced Mobile Phone Sytem h thng in thoi di ng
tin tin) c s dng M v c; TACS (Total Access Communication Sytem h
thng giao tip truy cp tng hp) c s dng Anh, C-45 Ty c, B o Nha v Nam
Phi, Radiocom 2000 Php; v RTMI Italia.1.1.2Mng thng tin di ng th h
2G1.1.2.1 Cng ngh s dng L th h kt ni thng tin di ng mang tnh ci cch
cng nh khc hon ton so vi th h u tin. Vi cng ngh GSM , n s dng cc tn
hiu k thut s thay cho tn hiu analog ca th h 1G v c p dng ln u tin
ti Phn Lan bi Radiolinja (hin l nh cung cp mng con ca tp on Elisa
Oyj) trong nm 1991. Mng 2G mang GVHD: Lm Hng Thch SVTH: Nguyn Th
Thu Hng 1 N TT NGHIPti cho ngi s dng di ng 3 li ch tin b trong sut
mt thi gian di: m ho d liu theo dng k thut s, phm vi kt ni rng hn
1G v c bit l s xut hin ca tin nhn dng vn bn n gin SMS. Theo , cc
tin hiu thoi khi c thu nhn s uc m ho thnh tn hiu k thut s di nhiu
dng m hiu (codecs), cho php nhiu gi m thoi c lu chuyn trn cng mt
bng thng, tit kim thi gian v chi ph. Song song , tn hiu k thut s
truyn nhn trong th h 2G to ra ngun nng lng sng nh hn v s dng cc
chip thu pht nh hn, tit kim din tch bn trong thit b hn.Nhng cng ngh
2G c chia lm hai dng chun : TDMA (Time Divison MutipleAccess:
atruycpphnchiatheothigian),vCDMA(CodeDivison Multple Access : a
truy cp phn chia theo m), ty thuc vo hnh thc ghp knh c s dngCc chun
cng ngh ch yu ca 2G bao gm:- GSM (thuc TDMA) c ngun gc t chu u,
nhng c s dng trn tt c cc quc gia 6 lc a. Ngy nay, cng ngh GSM vn cn
c s dng vi 80% in thoi di ng trn th gii.- IS-95 cn c gi l aka
cdmaOne (thuc CDMA, thng c gi ngn gn l CDMA ti M) c s dng ch yu l
chu M v mt s vng chu . Ngy nay, nhng thu bao s dng chun ny chim
khong 17% trn ton th gii. Hin ti, cc nc Mexico, n , c v Hn Quc c rt
nhiu nh cung cp mng CDMA chuyn sang cung cp mng GSM.- PDC (thuc
TDMA) l mng t nhn, ti Japan.- IS-136 aka D-AMPS (thuc TDMA thng c
gi tt l TDMA ti M) tng l mng ln nht trn th trng M nay chuyn sang
GSM.- iDEN (nn tng TDMA) s dng bi Nextel ti Hoa K v Telus Mobility
ti Canada.1.1.2.2c tnh ca mngGVHD: Lm Hng Thch SVTH: Nguyn Th Thu
Hng 2 N TT NGHIP cng ngh 2G tn hiu k thut s c s dng trao i gia in
thoi v cc thp pht sng, lm tng hiu qu trn 2 phng din chnh :- Th nht,
d liu s ca ging ni c th c nn v ghp knh hiu qu hn so vi m ha Analog
nh s dng nhiu hnh thc m ha, cho php nhiu cuc gi cng c m ha trn mt
di bng tn.- Th hai, h thng k thut s c thit k gim bt nng lng sng
radio pht t in thoi. Nh vy, c th thit k in thoi 2G nh gn hn; ng thi
gim chi ph u t nhng thp pht sng.Hn na, mng 2G tr nn ph bin cng do
cng ngh ny c th trin khai mt s dch v d liu nh Email v SMS. ng thi,
mc bo mt c nhn cng cao hn so vi 1G.Tuy nhin, h thng mng 2G cng c
nhng nhc im, v d, nhng ni dn c tha tht, sng k thut s yu c th khng
ti c cc thp pht sng. Ti nhng a im nh vy, cht lng truyn sng cng nh
cht lng cuc gi s b gim ng k.1.1.3Mng thng tin di ng th h
2.5G1.1.3.1 Cng ngh s dng2,5G chnh l bc m gia 2G vi 3G trong cng
ngh in thoi khng dy. Ch s 2.5G chnh l biu tng cho vic mng 2G c
trang b h thng chuyn mch gi bn cnh h thng chuyn mch theo knh truyn
thng. N khng c nh ngha chnh thc bi bt k nh mng hay t chc no v ch
mang mc ch duy nht l tip th cng ngh mi theo mng 2G.1.1.3.2 c tnh ca
mng Mng 2.5G cung cp mt s li ch tng t mng 3G v c th dng c s h tng c
sn ca cc nh mng 2G trong cc mng GSM v CDMA. V tin b duy nht chnh
GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 3 N TT NGHIPl GPRS - cng
ngh kt ni trc tuyn, lu chuyn d liu c dng bi cc nh cung cp dch v vin
thng GSM. Bn cnh , mt vi giao thc, chng hn nh EDGE cho GSM v
CDMA2000 1x-RTT cho CDMA, c th t c cht lng gn nh cc dch v c bn 3G
(bi v chng dng mt tc truyn d liu chung l 144 kbit/s), nhng vn c xem
nh l dch v 2.5G (hoc l nghe c v phc tp hn l 2.75G) bi v n chm hn vi
ln so vi dch v 3G thc s.* EDGE (Enhanced Data Rates for GSM
Evolution), hay cn gi l EGPRS, l mt cng ngh di ng c nng cp t GPRS -
cho php truyn d liu vi tc c th ln n 384 kbit/s dnh cho ngi dng c nh
hoc di chuyn chm, 144kbit/s cho ngi dng di chuyn vi tc cao. Trn ng
tin n 3G, EDGE c bit n nh l cng ngh 2.75G. Thc t bn cnh iu ch GMSK,
EDGE dng phng thc iu ch 8-PSK tng tc d liu truyn. Chnh v th, trin
khai EDGE, cc nh cung cp mng phi thay i trm pht sng BTS cng nh l
thit b di ng so vi mng GPRS.1.1.4Mng thng tin di ng ng i 3G1.1.4.1
Cng ngh s dng L th h truyn thng di ng th ba, tin tin hn hn cc th h
trc . N cho php ngi dng di ng truyn ti c d liu thoi v d liu ngoi
thoi (ti d liu, gi email, tin nhn nhanh, hnh nh, m thanh, video
clips...).,). H thng 3G yu cu mt mng truy cp radio hon ton khc so
vi h thng 2G hin nay. Trong cc dch v ca 3G, cuc gi video thng c m t
nh mt dch v trng tm ca s pht trin.Cng ngh 3G cng c nhc n nh l mt
chun IMT-2000 ca T chc Vin thng Th gii (ITU). Ban u 3G c d kin l mt
chun thng nht trn th gii, nhng trn thc t, th gii 3G b chia thnh 4
phn ring bit:- UMTS (W-CDMA)GVHD: Lm Hng Thch SVTH: Nguyn Th Thu
Hng 4 N TT NGHIP* UMTS (Universal Mobile Telecommunication System),
da trn cng ngh truy cp v tuyn W-CDMA, l gii php ni chung thch hp vi
cc nh khai thc dch v di ng (Mobile network operator) s dng GSM, tp
trung ch yu chu u v mt phn chu (trong c Vit Nam). UMTS c tiu chun
ha bi t chc 3GPP, cng l t chc chu trch nhim nh ngha chun cho GSM,
GPRS v EDGE.* FOMA, thc hin bi cng ty vin thng NTT DoCoMo Nht Bn nm
2001, c coi nh l mt dch v thng mi 3G u tin. Tuy l da trn cng ngh
W-CDMA, nhng cng ngh ny vn khng tng thch vi UMTS (mc d c cc bc tip
hin thi thay i li tnh th ny).- CDMA
2000*Lthhktipcaccchun2GCDMAvIS-95. Ccxut ca CDMA2000 c a ra bn tho
v p dng bn ngoi khun kh GSM ti M, Nht Bn v Hn Quc. CDMA2000 c qun l
bi 3GPP2 mt t chc c lp vi 3GPP. V c nhiucngngh truyn thngkhc nhauc
s dng trong CDMA2000 bao gm 1xRTT, CDMA2000-1xEV-DO v 1xEV-DV. *
CDMA 2000 cung cp tc d liu t 144 kbit/s ti trn 3 Mbit/s. Chun ny c
chp nhn bi ITU. *Ngitachorngsraithnh cngnhtca mngCDMA-2000lti KDDI
ca Nhn Bn, di thng hiu AU vi hn 20 triu thu bao 3G. K t nm 2003,
KDDI nng cp t mng CDMA2000-1x ln mng CDMA2000-1xEV-DO vi tc d liu
ti 2.4 Mbit/s. Nm 2006, AU nng cp mng ln tc 3.6 Mbit/s. SK Telecom
ca Hn Quc a ra dch v CDMA2000-1x u tin nm 2000, v sau l mng 1xEV-DO
vo thng 2 nm 2002.- TD-SCDMAChun c t c bit n hn l TD-SCDMA, c pht
trin ring ti Trung Quc bi cng ty Datang v Siemens.- Wideband
CDMAGVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 5 N TT NGHIPH tr tc
gia 384 kbit/s v 2 Mbit/s. Giao thc ny c dng trong mt mng din rng
WAN, tc ti a l 384 kbit/s. Khi n dng trong mt mng cc b LAN, tc ti a
ch l 1,8 Mbit/s. Chun ny cng c cng nhn bi ITU.1.1.4.2 c tnh ca mng
Trong s cc dch v ca 3G, in thoi video thng c miu t nh l l c u. Gi
tn s cho cng ngh 3G rt t ti nhiu nc, ni m cc cuc bn u gi tn s mang
li hng t Euro cho cc chnh ph. Bi v chi ph cho bn quyn v cc tn s phi
trang tri trong nhiu nm trc khi cc thu nhp t mng 3G em li, nn mt
khi lng vn u t khng l l cn thit xy dng mng 3G. Nhiu nh cung cp dch
v vin thng ri vo kh khn v ti chnh v iu ny lm chm tr vic trin khai
mng 3G ti nhiu nc ngoi tr Nht Bn v Hn Quc, ni yu cu v bn quyn tn s
c b qua do pht trin h tng c s IT quc gia c t ln lm vn u tin nht. V
cng chnh Nht Bn l nc u tin a 3G vo khai thc thng mi mt cch rng ri,
tin phong bi nh mng NTT DoCoMo. Tnh n nm 2005, khong 40% cc thu bao
ti Nht Bn l thu bao 3G, v mng 2G ang dn dn i vo lng qun trong tim
thc cng ngh ti Nht Bn.1.2 Cng ngh thng tin di ng tng lai4G l cngngh
a phng tin di ng ca tng lai. y l cng ngh truyn thng khng dy th h th
4, cho php truyn ti d liu vi tc ti a trong iu kin l tng ti 1-1,5
GB/s. NTT Docomo xem 4G nh s m rng ca mng thng tin di ng t bo 3G.
Cc nghin cu u tin ca NTT DoCoMo cho bit, in thoi 4G c th nhn d liu
vi tc 100 Mbit/s khi di chuyn v ti 1 Gbit/s khi ng yn, cng nh cho
php ngi s dng c th ti v truyn ln cc hnh nh, video clips cht lng
cao. Mng in thoi 3G hin ti ca DoCoMo c tc ti l 384 Kbit/s v truyn d
liu ln vi tc 129 Kbit/s. NTT DoCoMo cng hy vng trong vng 2010 -
2012 s c th a mng 4G vo kinh doanh. .Quan im ny c xem nh l mt GVHD:
Lm Hng Thch SVTH: Nguyn Th Thu Hng 6 N TT NGHIPquan im tuyn tnh,
trong mng 4G s c cu trc t bo c ci tin cung ng tc ln trn 100 MB/s.
Vi cch nhn nhn ny, 4G s chnh l mng 3G LTE, UMB hay WiMAX
802.16m.1.2.1 Hng n h thng 4GCc gi thit v tc d liu l mc ch cho s
nghin cu v kho st trn cc cng ngh c s cn thit thc hin vin cnh . Yu
cu k thut h thng v thit k tng lai s da vo cc kt qu ca s nghin cu v
kho st ny. Do yu cu tc d liu cao, ph tn b sung s cn cho cc kh nng
mi ca h thng IMT-2000 m rng. Cc mc tiu v tc d liu cho thy s tin b
trong cng ngh v cc gi tr ny c mong i s t c bi tin ca cng ngh trong
khong thi gian nghin cu v pht trin kh nng mi ca cc h thng IMT-2000
m rng.Cng vi s pht trin trong tng lai ca IMT-2000 v cc h thng
IMT-2000 m rng. S c mt mi quan h ngy cng tng gia vic truy nhp v
tuyn v cc h thng thng tin lin lc, v d nh mng WPAN, LAN, qung b s v
truy nhp khng dy c nh. Da vo cc yu cu v dch v c vch ra, d tnh lu
lng v cng ngh truy nhp v tuyn, ITU-R lm vic trn cu trc h thng tim
nng, tng ngt hnh 1.1 n hnh 1.3. Trong trnghpny, tnh lu ng chm s c
tnh bng tc i b ( 3km/h), tnh lu ng trung bnh tng ng vi tc xe t
trong thnh ph ( 50-60km/h), lu ng nhanh tng ng vi tc trn ng cao tc
hoc xe la tc cao ( 60km/h n 250km/h hoc hn na). lu ng v c bn cng
lin quan n kch thc cell trong h thng t bo, cng nh kh nng ca h thng.
Ni chung, kch thc cell trong mt h thng t bo phi ln hn mt lu ng cao
no gim ti chuyn giao trong mng.GVHD: Lm Hng Thch SVTH: Nguyn Th Thu
Hng 7 N TT NGHIPHnh 1.1Nng lc ca cc h thng3G m rng.GVHD: Lm Hng
Thch SVTH: Nguyn Th Thu Hng 8 N TT NGHIPHnh 1.2Mng tng lai thng
nht, bao gm nhiuh thngtruy nhp an xen nhauT vin cnh ca ngy hm nay,
ITU-R s bt u chun ha h thng, vi cc bng tn c xc nh v bc u trin khai
cc h thng IMT-2000 m rng sau nm 2010. H thng truy nhp tng lai s bao
gm nhng cng ngh truy nhp m rng v sn c. Ngoi ra, cc cng ngh truy nhp
v tuyn mi s t c tc d liu cao cho truy nhp khng dy c tnh lu ng thp v
cho trng hp t bo vi tnh lu ng cao. Yucu tc d liu cho trng hp t bo l
mtthch thc ln ca vin cnh cng ngh cng vi ph tn tng lai s c s
dng.1.2.2 Tm hiu s lc v h thng 4GVic tin n h thng thng tin di ng 4G
c t ra gii quyt cc vn vn cn tn ti h thng 3G v cng cung cp kh nng p
ng rng cho cc dch v mi, t thoi cht lng cao n truyn hnh phn gii cao,
cho n cc knh v tuyn tc d liu cao. Thut ng 4G c s dng vi mt ngha rng
bao gm cc loi khc nhau ca h thng truyn thng truy nhp v tuyn bng
rng, khng ch ring h thng in thoi t bo. Mt trong cc thut ng cng c
dng miu t 4G l MAGICa truynthngdi ng(Mobilemultimedia),milcmini
(Anytime GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 9 N TT
NGHIPanywhere), h tr lu ng ton cu (Global mobility support), gii
php v tuyn tch hp (Integrated wireless solution), v dch v thu bao c
nhn (Customized personal service). H thng 4G khng ch s h tr cc dch
v di ng th h sau m cn h tr cho cc mng v tuyn c nh.1.2.3 Mc tiu thit
k h thng thng tin 4G1.2.4.1 Thng tin bng rng T trc n nay, lu lng
trn mng thng tin di ng vn ch yu l lu lng thoi. H thng th h 2G, h
thng t bo s c nhn PDC (Personal Digital Cellular) gii thiu cc dch v
I-mode. Nhng dch v ang c ph bin hin nay nh: truy cp Internet, thng
mi in t, e-mail. Nhng dch v ny ch yu l thng tin d liu da trn vn bn
qua mng t bo. H thng IMT-2000 xut nhng dch v tc cao t 64 n 384
kbit/s, v t l lu lng s liu trn thoi tng ln. Tuy nhin, s pht trin
mnh ca cc dch v bng rng nh ADSL (Asymmetric Digital Subscriber
Line), cc h thng truy nhp cp quang, cc mng LAN c quan, gia nh lm
tng nhu cu s dng cc dch v tng ng ca mng thng tin di ng.1.2.4.2Chi
ph thpKhi cc dch v bng rng pht trin, cc thu bao c th trao i rt nhiu
loi thng tin vi nhau, tuy nhin h li khng sn sng tr mt chi ph qu cao
cho lng thng tin trao i qu nhiu nh vy. V vy cn phi gim gi cc ca cc
dch v xung bng hoc thp hn gi cc ca cc dch v hin ti. H thng IMT-2000
gim mc cc tnh theo bt v a ra cc mc gi tng i thp, nhng h thng 4G i
hi mt knh bng thng rng vi mc gi thm ch thp hn mc gi theo bit m
IMT-2000 a ra.GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 10 N TT
NGHIPHnh 1.3Nhng vn k thut lin quan n cng ngh v tuyn1.2.4.3Vng ph
sng rngMt trong nhng c tnh ca thng tin di ng l c mt khp mi ni mi
lc. Nhng kh nng ny cng l mt tiu ch quan trng cho s pht trin ca thng
tin di ng trong tng lai. Khi mt h thng mi u tin c gii thiu th ni
chung rt kh khn trong vic cung cp mt vng ph sng rng nh mng hin c, v
khch hng s khng mua cc thit b u cui mi nu h b gii hn vng ph
sng1.2.4.4Dch v a dng v d s dngi tng s dng thng tin di ng rt a dng
v rt khc nhau. Trong tng lai, chng ta hy vng c th nng cao phm cht v
chc nng h thng c th cung cp nhiu loi hnh dch v, khng ch l cc dch v
thoi truyn thng m cn truyn cc thng tin lin quan n tt c nm gic quan
ca con ngi. V thu bao phi d dng s dng cc dch v ny (d dng ci t, d
dng kt ni, ).GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 11 N TT
NGHIP1.2.4.5Tc truyn dni tng s dng thng tin di ng rt a dng v rt khc
nhau. Trong tng lai, chng ta hy vng c th nng cao phm cht v chc nng
h thng c th cung cp nhiu loi hnh dch v, khng ch l cc dch v thoi
truyn thng m cn truyn cc thng tin lin quan n tt c nm gic quan ca
con ngi. V thu bao phi d dng s dng cc dch v ny (d dng ci t, d dng
kt ni, ).Mc tiu thit k h thng p nhng yu cu trn y. Coi thng tin d
liu v video l dch v chnh, h thng 4G phi cung cp tc truyn dn cao hn
vi dung lng ln hn (c v s lng thu bao l lu lng) IMT-2000.Hin nay,
coi tc chnh l cht lng truyn dn, mng LAN t c tc t 10 n 100 Mbit/s, v
tc ca mng ADSL cng t c 2-3 Mbit/s. Mc tiu thit k h thng thng tin di
ng l t tc xp x 100 Mbit/s i vi mi trng ngoi tri v c Gbit/s vi mi
trng trong nh. S khng c ch cho mng thng tin di ng th h mi nu khng c
tc ln hn t nht 10 ln tc hin ti ca IMT-2000. m thng tin thi gian thc
gia cc thit b u cui vi nhau th h thng mi cn phi gim thi gian tr
truyn dn xung di 50 ms. Gi s rng cc dch v trong tng lai s da trn
truyn dn IP (Internet Protocol), hiu qu truyn dn gi IP qua mng v
tuyn cngcnphitnh n.Hthng mi bn cnh vicnng cao dung lng truyn dn phi
m bo c vic gim chi ph. Chi ph tnh trn 1 bt truyn dn phi gim xung
bng 1/10 hoc 1/100 mc chi ph hin ti bng cch gim chi ph thit b h
tng, chi ph hot ng v chi ph xy dng. Mc tiu thit k c cp trn y tp
trung vo nhng dch v c phm cht tt hn cc dch v hin ti, v d dng s dng.
iu m nhng nh i tin phong trong th trng dch v 4G cn phi lu l kh nng
tch hp h thng LAN khng dy trong nh vi h thng hu tuyn v thc hin trin
khai cc dch v mi trong thi gian ngn.GVHD: Lm Hng Thch SVTH: Nguyn
Th Thu Hng 12 N TT NGHIP1.2.4Nhng vn c bn trong cu hnh h thng 4GVn
k thut cn thit i vi mng thng tin di ng th h 4G p ng nhng yu cu c nu
ra phn trn c trnh by trn hnh 1.7.1.2.5.1. Dung lng ln v tc truyn dn
caoIMT-2000trinkhaiatruynhptheombngrngWCDMA(Wideband Code Division
Multiple Access) v t c tc 2Mbit/s vi bng tn c rng 5 MHz. Ngy nay,
vic pht trin k thut iu ch v gii iu ch thch nghi a lp cho php tc
truyn dn t xp x 10 Mbit/s vi cng mt bng tn s dng. t c tc truyn dn t
100 Mbit/s n 1 Gbit/s, chng ta cn phi s dng bng tn ln hn v cc h
thng truyn dn mi ph hp vi truyn dn tc cao.i vi thng tin d liu, chng
ta s cn h thng truy nhp v tuyn c th truyn dn gi tin hiu qu. Tm quan
trng ca vic ph sng trong nh thc y cc cng ngh phi pht trin theo hng
c th s dng cho c mi trng truyn sng trong nh v ngoi tri. c c nhng
bng tn rng cho truyn dn tc cao v p ng nhu cu lu lng thoi ang tng
cao, chng ta phi quan tm n cc bng tn mi, v pht trin cc phn t mng cn
thit nh cc b khuch i, cc b lc v tnh ton suy hao truyn sng cho nhng
bng tn ny. Cng vi vic nghin cu pht trin cc gii php s dng hiu qu ti
nguyn ph tn hn ch cng rt cn thit.1.2.5.3 Kt ni mng da trn cng ngh
IPMt bin php cho nhng thu bao s dng h thng mi khng gp phi vn v vng
ph sng l phi m bo cc thit b u cui mi phi h tr hot ng trn c h thng c
v h thng mi. Mt khc, chng ta phi tnh n kh nng roaming quc t, mt
thit b u cui phi c h tr hot ng trn nhiu h thng nh s dng cng ngh SDR
(Softwave Defined Radio). Vi cng ngh ny, thit b u cui c th hot ng
trn nhiu bng tn khc nhau ca cc quc gia v khu vc khc nhau. GVHD: Lm
Hng Thch SVTH: Nguyn Th Thu Hng 13 N TT NGHIPHn na, mng thng tin di
ng trong tng lai phi tch hp vi nhiu phng thc truy nhp khc nhau, vi
rt nhiu loi cell c cc kh nng kt ni lin mng da trn cng ngh IP. Chnh
v vy, kt ni lin mng v chuyn giao gia cc h thng truy nhp l mt yu cu
cn thit ngoi yu cu v kh nng chuyn giao v roaming ni b v gia hai mng
thng tin di ng vi nhau.1.2.5.4Cu hnh h thng da trn IPH thng 4G phi
c cu hnh kt ni vi mng IP, truyn dn hiu qu cc gi IP, cng tn ti vi cc
h thng truy nhp khc, linh hot khi a vo khai thc, c kh nng m rng khi
cn, Cc mng IP cng c th kt ni d dng hoc ph hp vi cc h thng truy nhp
v tuyn khc hn cc h thng 4G. im truy nhp v tuyn
4G(4G-AP-4GAccessPoint)scktnivimtbnhtuyntruynhpAR (Access Router)
nh trn Hnh 1.4. 4G-AP c cc chc nng iu khin truyn dn v tuyn, chuyn
giao, cho php cc thit b di ng lin lc vi nhau da trn IP. Cc 4G-AP s
c t tng ng vi cc cell ca chng. Khi mt thit b di ng di chuyn gia cc
cell, vic chuyn giao s c thc hin bng chuyn mch n gin gia cc im truy
nhp v cc vng v tuyn nu hai im 4G-AP kt ni vi cng mt AR. Nu hai im
4G-AP thuc hai AR khc nhau th nh tuyn truyn dn gi tin trong mng IP
phi thay i tc th. Lit kt hot ng gia chuyn mch 4G-IP v nh tuyn mng
IP ng mt vai tr rt quan trng i vi qu trnh chuyn giao. i vi chuyn
giao gia mt 4G-AP v mt AP ca h thng khc, thit b di ng phi c chc nng
truy nhp c hai mng. Chuyn giao s c thc hin bng vic theo di v so snh
gia cc h thng khc nhau la chn c mt h thng ph hp.GVHD: Lm Hng Thch
SVTH: Nguyn Th Thu Hng 14 N TT NGHIPHnh 1.4C u hnh hth ng 4G
1.2.5.5Phn loi v cu hnh cell theo mi trng truyn dnH thng 4G c cell
ngoi tri, trong nh, trong phng tin di chuyn, nh trn Hnh 3. Nhng
cell ngoi tri c vng ph sng rng, cho php cc thit b u cui ang di
chuyn vi tc cao trao i thng tin vi tc cao. Vng ph trong nh c thc
hin bi cc indoor AP. Cc Indoor AP c thit k khng ch gip trao i thng
tin tc cao v hot ng n gin m cn p ng nhng yu cu ca mt mng LAN v tuyn
tng lai.Ngoi ra, cc cell trong phng tin giao thng di chuyn nh xe
but, tu ho (c gi l cc cell/mng di ng) c phc v bi mt b nh tuyn di ng
MR (Mobile Router). MR c chc nng chuyn tip tn hiu gia trm gc v thit
b u cui trn phng tin, nn nhng thit b u cui ny khng lin lc trc tip
vi trm GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 15 N TT NGHIPgc nh
thng thng. Cu hnh ny c thit k t c hiu qu v cng sut pht ca thit b u
cui, tc truyn dn, ln ca tn hin iu khin. Kt ni multi-hop a chng, mt
phng php hiu qu m rng kch thc cell s c nghin cu nh l mt cch gii
quyt vn cc im cht gy ra bi hiu ng bng. Truyn dn d liu qua trm chuyn
tip c thc hin ngay c khi b gii hn v cng sut pht ca thit b u cui v
suy hao truyn sng ln.1.2.5.6Thng tin a phng tinCu hnh h thng 4G cho
php truyn dn vi tc cao, hot ng lin kt vi cc mng IP trong khi vn phi
m bo c QoS ca truyn dn gi.Hnh 1.5 Lin l c thng qua cc k t n i
multi-hop 1.2.5 Cng ngh cho 4GTip theo mng thng tin di ng (TTD) th
h th 3 (3G - 3rd Generation), Lin minh Vin thng quc t (ITU) ang hng
ti mt chun cho mng di ng t bo mi GVHD: Lm Hng Thch SVTH: Nguyn Th
Thu Hng 16 N TT NGHIPth h th 4 (4G - 4th Generation). 4G c nhng tnh
nng vt tri nh: Cho php thoi da trn nn IP, truyn s liu v a phng tin
vi tc cao hn rt nhiu so vi cc mng di ng hin nay Theo tnh ton, tc
truyn d liu c th ln ti 100 Mb/s, thm ch ln ti 1 Gb/s trong cc iu
kin tnh.Hnh 1.6S tm lc qu trnh pht trin ca mng thng tin di ng t bo3
cng ngh di y c xem l cc cng ngh tin 4G, l cc cng ngh lm s c xy dng
nn chun 4G trong tng lai. LTE (Long-Term Evolution)T chc chun ha
cng ngh mng TTD t bo th h th ba 3G UMTS 3GPP (3rd Generation
Partnership Project) bao gm cc t chc chun ha ca cc nc chu , chu u v
Bc M bt u chun ha th h tip theo ca mng di ng 3G l LTE. LTEc xy dng
trn nn cngngh GSM(Global Systemfor Mobile Communications), v th n d
dng thay th v trin khai cho nhiu nh cung cp dch v. Nhng khc vi GSM,
LTE s dng phng thc ghp knh phn chia theo tn s trc giao (OFDM) -
truyn d liu tc cao bng cch phn chia thnh cc sng mang GVHD: Lm Hng
Thch SVTH: Nguyn Th Thu Hng 17 N TT NGHIPcon trc giao. LTE s dng ph
tn mt cch thch hp v mm do, n c th hot ng bng tn c rng t 1,25 MHz
cho ti 20 MHz. Tc truyn d liu ln nht (v l thuyt) ca LTE c th t ti
250 Mb/s khi rng bng tn l 20 MHz. LTE khc vi cc cng ngh tin 4G khc
nh WiMAX II ch, n ch s dng OFDM hng ln, cn hng xung n s dng a truy
nhp phn chia theo tn s n sng mang nng cao hiu qu trong vic iu khin
cng sut v nng cao thi gian s dng pin cho thit b u cui ca khch hng.
UMB (Ultra Mobile Broadband)T chc chun ha cng ngh mng TTD th h th
ba CDMA2000 3GPP2 (3rd Generation Partnership Project 2) c thnh lp
v pht trin bi cc t chc vin thng ca Nht Bn, Trung Quc, Bc M v Hn Quc
cng vi cc hng nh Alcatel-Lucent, Apple, Motorola, NEC v Verizon
Wireless. Thnh vin ca 3GPP2, Qualcomm l hng i u trong n lc pht trin
UMB, mc d hng ny cng ch tm c vo vic pht trin LTE. UMB da trn CDMA
(Code Division Multiple Access) c th hot ng bng tn c rng t 1,25 MHz
n 20 MHz v lm vic nhiu di tn s. UMB c xut vi tc truyn d liu ln ti
288 Mb/s cho lung xung v 75 Mb/s cho lung ln vi rng bng tn s dng l
20 MHz. Cng ngh ny s cung cp kt ni thng qua cc sng mang da trn a
truy nhp phn chia theo m CDMA. IEEE 802.16m (WiMAX II)IEEE 802.16 l
mt chui cc chun do IEEE pht trin, chng h tr c c nh (IEEE
802.16-2004) v di ng (IEEE 802.16e-2005). IEEE 802.16m (hay cn gi l
WiMAX II) c pht trin t chun IEEE 802.16e, l cng ngh duy nht trong
cc cng ngh tin 4G c xy dng hon ton da trn cng ngh a truy nhp phn
chia theo tn s trc giao OFDMA (k thut a truy cp vo knh truyn OFDM).
GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 18 N TT NGHIPCng ngh WiMAX
II s h tr tc truyn d liu ln ti 100 Mb/s cho cc ng dng di ng v c th
ln ti 1Gb/s cho cc ngi dng tnh. Khong cch truyn ca WiMAX II l khong
2 km mi trng thnh th v khong 10 km cho cc khu vc nng thn.Hng Intel
ang dn u v xut s dng v pht trin WiMAX II cho h thng 4G, mt chin lc
m cc Hng Alcatel-Lucent, AT&T, Motorola, Nokia, Samsung, Sprint
Nextel v cc thnh vin khc ca WiMAX Forum cng h tr tch cc. 1.2.6 Kt
lun chng H thng thng tin di ng 4G v ang c nghin cu nhiu ni trn th
gii. Vi mc ch gii thiu nhng nt c bn nht v h thng thng tin di ng
trong tng lai, h thng 4G. H thng 4G l h thng khng dy c tc truyn dn
cao ph hp vi nhng nhu cu ngy cng cao ca con ngi. Chng 1gii thiu v
nhng th h thng tin di ng p dng v qu trnh i ln ca h thng thng tin di
ng Vit Nam v chng 1 cng trnh by cc cng ngh ca 4G trong tng lai nh
l: LTE, UMB v IEEE 802.16m. V cng ch ra c nhng u im ca 4G vt tri hn
nhng cng ngh truy nhp v tuyn hin nay.GVHD: Lm Hng Thch SVTH: Nguyn
Th Thu Hng 19 N TT NGHIPChng 2M HA KNH TRONGTHNG TIN DI NG2.1 Qu
trnh m ha v nguyn l2.1.1 Qu trnh m ha Mt lung thng tin i xuyn qua
mt mng truy nhp v tuyn s nh l UTRAN phi tri qua nhiu qu trnh m ha,
cm t trong hnh 2.1. Thng tin a vo h thng ny phi dng s (d liu) hoc
cng c th l thng tin tng t (thoi). Chc nng m ngun l chuyn i lu lng
ngi s dng sang dng s v m rng hn na l nn d liu. B m ha ngun ph thuc
vo loi thng tin cn m ha. Tc c m ha bng cch s dng mt b m ha tc (b m
a tc thch nghi AMR, trong UTRAN), truyn hnh th s dng b m ha hnh. B
m ha ngun c gng m ha thng tin thnh mt s lng bit thp nht c th m b
gii m ngun pha thu c th xy dng li thng tin ngun nu khng c li no c
to ra trong sut qu trnh truyn ca n. Cc k thut nn khc nhau c th c s
dng t c mc ch m ha ngun. M ha ngun c th b i hu ht cc thng tin d tha
ca ngi s dng.Mt dngkhc ca phn d c thm vo sau lung d liu d liu c th
c ti to li my thu mc d iu ny s lm tn tht bng thng ca knh v tuyn.Bng
cch chn cc bit kim tra c tnh ton trc vo pha sau ca lung d liu ca
ngi s dng, m ha knh s tr nn ng tin cy hn trong qu trnh pht cc bit
thng tin qua giao din v tuyn. Knhtruyn c thgyra li cho cc bit pht,
cc li ny trc ht phi c pht hin v sau c sa li nu c th. Nhim v ny kh c
th thc hin c nu khng thm vo mt s thng tin ph (cc bit kim tra) vo
lung d liu. S lng bit d liu lun c tng ln trong m ha knh. S lng cc
bit ny c tng ln bao nhiu l ty thuc vo tng s m ha. B iu ch s GVHD:
Lm Hng Thch SVTH: Nguyn Th Thu Hng 20 N TT NGHIPnhn chui bit t b m
ha knh v chuyn i lung c m ha knh thnh dng sng thch hp vi knh truyn.
Trong UTRAN, phng php iu ch l QPSK (hoc 16 QAM) hng xung v QPSK
knhi (HPSK)Hnh 2.1Qu trnh m ha trong h thngtruynthngs 2.1.2 Nguyn l
m ha Vo na cui thp nin 40 ca th k trc, Claude Shannon pht trin mt b
nguyn l m ngy nay chng ta vn thng bit n vi tn ginh lutShannon. Vn m
Shannon nghin cu l s lng thng tin ti a c th truyn qua knh truyn c
nhiu tc ng. Trc , n vn c mong i l s cao hn tc d liu v cng cao th iu
tt yu l phi chp nhn li truyn. Shannon chng t rng khng nht thit phi
nh vy, trong mt chng mc no , ta c th t c t l li gn bng 0, c th t ti
dung lng knh ti a hoc bt k tc no di dung lng knh.Dung lng knh ti a
c th c xc nht ng thc sau:GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng
21 N TT NGHIPC = W log2 (1+S/N)Trong , W l bng thng ca knh truyn,Sl
cng sut ca tn hiu v Nl cng sut nhiu. nh lut ny thit lp tc truyn d
liu tuyt i c th t ti. Ta c th d dng nhn ra rng nu tng bng thng hoc
cng sut ca tn hiu ln th c th tng dung lng knh ti a ln cao hn. Cn
rng khi tng mc nhiu ln th ta cng phi tng mc tn hiu ln vn m bo c tc
truyn d liu nh trc lc tng mc nhiu. T s tn hiu trn nhiu S/N thng c s
dng nh t s gia mc nng lng trn bit (Eb) v mc nng lng trn Hertz (N0)
ca nhiu,t s Eb/N0.Nguyn l ny rt quan trng v cn thit phi ghi nh, c
bit trong mt h thng WCDMA nh UTRAN, ni m qu trnh truyn ca nhng ngi
s dng gy nhiu ln nhau.2.2 Vai tr ca m ha Mc ch ca l thuyt M ha trn
knh truyn (channel encoding theory) l tm nhng m c th truyn thng
nhanh chng, cha ng nhiu m k (code word) hp l v c th sa li (error
correction) hoc t nht pht hin cc li xy ra (error detection). Cc mc
ch trn khng ph thuc vo nhau, v mi loi m c cng dng ti u cho mt ng
dng ring bit. Nhng c tnh m mi loi m ny cn cn tu thuc nhiu vo xc sut
li xy ra trong qu trnh truyn thng.Mi m thng ch thch hp cho mt ng
dng nht nh. Vin thng trong v tr (deep space) b gii hn bi nhiu nhit
(thermal noise) trong thit b thu. Hin trng ny khng xy ra mt cch t
pht bt thng, song xy ra theo mt chu trnh tip din. Tng t nh vy,
modem vi di tn hp b hn ch v nhiu m tn ti trong mng li in thoi. Nhng
nhiu m ny c th c biu hin r hn bng mt m hnh m tp tip din. in thoi di
ng "Cell phones" hay c vn do s suy sng nhanh GVHD: Lm Hng Thch
SVTH: Nguyn Th Thu Hng 22 N TT NGHIPchng xy ra. Tn s cao c dng c th
gy ra s suy sng tn hiu mt cch nhanh chng (rapid fading), ngay c khi
my nhn ch di ch vi phn Anh (inches) 1. Mt ln na, ngi ta hin c mt
loi thuc hng M ha trn knh truyn c thit k i u vi tnh trng suy
sng.2.3 Cc phng php m ha knh trong h thng 3G2.3.1 M khi M khi thao
tc d liu trn mt khi ti cng mt thi im. B m ha s thm mt s bit kim tra
vo khi bit d liu v b gii m s s dng chng xc nh rng c li no xy ra
trong qu trnh truyn hay khng. Do , s bit ng ra ca b m ha lun lun ln
hn ng vo. T s gia khi bit thng tin k (ng vo) v khi bit c m ha knh n
(ng ra) c gi l t l m ha:Rc = k/nB m tng ng c xem nh l b m (n,k). Do
, phn bit kim tra c cng thm vo b m (n,k) s l (n k)/n. Cng nhiu bit
kim tra cthm vo th kh nng xc nh li ca b gii m knh s cng tt hn. Tuy
nhin, cc bit kim tra cng s lm tn bng thng ca knh truyn nn cn phi tm
ra mt s cn bng tt nht.Ty thuc vo cch m cc bit kim tra c thm vo t m
n m b m nhn c c th c gi l b m h thng hoc khng h thng. Trong b m h
thng, cc bit kim tra s c trn ln cng vi cc bit thng tin.C 2k khi
thng tin c sp xp vo 2n t m. Nh chng ta thy, hu ht 2n t m s khng c s
dng pha bn tri. B t m c s dng th khng c chn mt cch ngu nhin m theo
cch tt nht b gii m knh c th thc hin c.GVHD: Lm Hng Thch SVTH: Nguyn
Th Thu Hng 23 N TT NGHIPHnh 2.2M ha khiKhong cch Hamming c o gia 2
t m khc nhau. V d, nu ta c 2 t m a v b nh sau:a = 100110001b =
100101001Khong cch Hamming d(a,b)= 2 v 2 t m ny khc nhau chnh xc 2
v tr bit (bit 5 v 6). Khong cch nh nht gia tt c cc t m trong b m c
gi l khong cch ti thiu dmin. l mtn v o rt quan trng v n ch ra b m
ny tt n mc no trong vic pht hin li. Khong cch ti thiu l i ch ra rng
b gii m knh c th pht hin i 1 bit li. Nu c nhiu hn i -1 bit li th t
m thu c s ging vi t m hp l no ; do , n s c chp nhn nh l mt t mng.M
khi thng c s dng vi mt phng php yu cu lp li t ng ARQ. M khi rt hiu
qu trong vic tm li v khi tm thy li, mt yu cu pht li khi b li s c
pht ra t mt thc th ngang hng. S phi hp ny i hi d liu hng khi (block
oriented), nhng rng buc v mt thi gian i vi d liu khng c GVHD: Lm
Hng Thch SVTH: Nguyn Th Thu Hng 24 N TT NGHIPcht ch nn d liu ca ngi
s dng phi chu c s tr hon. Mi qu trnh truyn li s lm tng thm tr
truynca ton b h thng.Hnh 2.3B m c tnh h thngv khngh thngPhng php
kim tra d tha vng CRC l mt phng php ph bin ca m ha khi. Cc bit CRC
cng c s dng trong WCDMA. Vic thm vo cc bit CRC c thc hin trc khi m
ha knh v chngs ckim tra li sau khi gii m knh. Kch thc ca trng CRC c
thm vo cho mt khi truyn c th l 0, 8, 12, 16 hoc 24 bit trong WCDMA.
Cc a thc sinh tng ng c cho trong bng 2.1. a thc sinh c th c gii
thch vi mt v d t bng ny. a thc sinh CRC: D8 + D7 + D4 + D2 +D + 1
ng ngha vi chuibit 110010111. Khi thng tin c chia modulo 2 cho a
thc sinh v phn s d sc dng lm trng kim tra (checksum).Bng 2.1Cc a
thc sinh CRCGVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 25 N TT NGHIPS
lng bit CRC a thc24161208D24 + D23 + D6 + D5 + D + 1D16 + D12 + D5
+ 1D12 + D11 + D3 + D2 + D + 1D8 + D7 + D4 + D2 + D + 1Ngoi ra cn c
mt s loi m khi c th c s dng cho mc ch sa li mc d chng khng c s dng
trong WCDMA. 2.3.2 M xon K thut m ha xon l mt cch khc bo v cc bit
thng tin khi cc li c th xy ra. Trong khi m khi c s dng pht hin li v
c ch ARQ c th sa chng th m xon kt hp c 2 chc nng ny. M xon thng c s
dng khi nhng s rng buc v mt thi gian l cht ch v khng cn dng n c ch
ARQ. D liu c m ha phi cha thng tin kim tra to cho n mt kh nng c th
sa c t nht l mt s li cpht hintrong b gii m knh m khng cn phi yu cu
lp li.C chny c bit nnh lc chsa li hng ti FEC. Mythu khng yu cu pht
li khi pht hin li m n s c gng t sa li .M xon khc vi m khi ch n hot
ng lin tc trn cc lung d liu. N c mt b nh, iu c ngha l cc bit ng ra
khng ch ph thuc vo cc bit vo hin ti m cn ph thuc vo nhiu bit vo trc
na. Mt m xon do c th c miu t bng cch s dng dng (n, k, m), trong n l
s bit ng ra trn mtt d liu, k l s bit ng vo v m l chiu di b nh ca b
m ha. T l m ha ca m xoncng ging vi m khi:Rc = k/nGVHD: Lm Hng Thch
SVTH: Nguyn Th Thu Hng 26 N TT NGHIPMt b m xon (3, 1, 9) c miu t
hnh 2.4. N l mt s kt hp gia thanh ghi dch D v cc b chc nng XOR. phn
cui ca chui d liu va c m ha, b m ha s thm vo m 1 bit 0 vo chui ng
ra. iu ny cthc hin tun hon m bo b m ha tr li trng thi ban u. Mi ln
mt b m ha xon b trn ngp bi cc li knhth tht kh khn c th phc hi li c
t s hn n ca n. Vic t li trng thi theo chu k c th gii quyt c vn . Cu
trc ca b m ha th n gin hn v hot ng ca n cng khng phc tp lm. Tuy
nhin, b gii m th khc hon ton.Hnh 2.4B m ha xon t l 1/3B gii m ti u
l b nh gi chui ng nht MLSE da trn tng mt chui bit c gii hn, my thu
s to ra tt c cc chui m b m ha c th gi. Tip my thu s so snh chui bit
nhn c thc s vi mi chui m n to ra v tnh khong cch Hamming ca mi cp
chui. Khong cch Hamming nh nht s nhn din c chui c pht ging nht.Phng
php MLSE cung cp b gii m xon hiu qu nht nhng vn l mi ln chiu di ca
chui bit c pht tng th s phc tp ca thut ton MLSE s tr GVHD: Lm Hng
Thch SVTH: Nguyn Th Thu Hng 27 N TT NGHIPnn kh kim sot. Mt gii php
cho vn ny l s dng thut ton Viterbi c th c tnh sao cho thut ton MLSE
hp l vn gi chiu qu.Cc b gii m xon c th l b gii m quyt nh cng hoc
mm. S phn bit ny da vo cch m b gii m nhn bit thng tin t b gii iu
ch. Trong phng php quyt nh cng, ng ra ca b gii iu ch l bit 0 hoc 1.
Cn trong phng php quyt nh mm, b gii iu ch gi n khng ch bit nhn c (0
hoc 1) m cn c mt s c lng v kh nng tin cy ca quyt nh . Vic c lng c
th da trn mt s c s nh l mc tn hiu thu c hin ti. B gii m sau c th s
dng d liu c lng ny nh l mt thng s trong thut ton gii m ti u ca n.B
gii m xon lm vic tt c th trnh khi cc li ngu nhin nhng nhc im ca
chng l d gy ra cc cm li, c trng trong cc h thng thng tin di ng. Cc
thit b ca ngi s dng (UE) di chuyn nhanh trong cc h thng CDMA c th
gy ra cc li khi nu kh nng iu khin cng sut khng nhanh kim ch nhiu. i
ph vi vn ny, ngi ta chia khi bn tin cn gi thnh cc cm ngn ri hon v
cc cm ny vi cc cm ca khi bn tin khc, nh vy khi xy ra cm li di, mi
bn tin ch mt i mt cm nh, phn cn li ca bn tin vn cho php b gii m khi
phc li ng sau khi sp xp li cc cm ca bn tin theo th t pha pht. Qu
trnh ny c gi l ghp xen tn hiu (interleaving), mc ch l tri cc bit li
ra trn mt khong thi gian di v do lm cho b gii m xon hiu qu hn.2.3.3
M turboM Turbo l mt pht minh tng i mi, n c cp n ln u tin vo nm
1993. N t c hiu sut rt cao v n c th thc hin gn n gii hn l thuyt ca
nh lut Shannon. Hiu sut ca n tti u vi cc dch v tc d liu cao v khng
hiu qu my i vi cc dchv tc thp.GVHD: Lm Hng Thch SVTH: Nguyn Th Thu
Hng 28 N TT NGHIPTrong m ha Turbo, ng ra ca qu trnh gii m s c s dng
iu chnh li d liu ng vo.M turbo u tin s dng 18 vng lp.B m ha Turbo c
s dng trong UTRAN v c trnh by trong hnh 2.5. B m ha ny l mt b m xon
c ni song song (PCCC). N bao gm 2 b m xon song song nhau v c cch ly
bi b ghp xen. Cc b m ha l quy v c tnh h thng. iu ny ch ng i vi b m
Turbo. Cc b m ha cng c th c ni tun t vi nhau (b m xon c ni tun t
SCCC), trong trng hp ny, b ghp xen c t gia cc b m ha. Cc b m ha cng
c th l cc b mkhi thay v b m ha xon, trong trng hp , b m ha Turbo s
l mt b m khi c ni song song PCBC hoc mt b m khi c ni tun t SCBC.Hnh
2.5 B m ha TurboNhim v ca b ghp xen l ngu nhin ha d liu trc khi n n
b m ha th 2. B ghp xen gm c mt ma trn vung. N cho php hon v c 2 dng
GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 29 N TT NGHIPintra-row v
inter-row cho cc bit ng vo v chui bit ng ra c xn bt bng cch xa cc
bit ny m khng cn tch chui bit ng vo.B gii m Turbo c m t hnh 2.6. N
gm c 2 b gii m SISO c ni vi nhau bi b ghp xen v b gii ghp xen. Tn
hiu t ng ra ca b gii m th 2 c lm tr v hi tip tr li ng vo ca b gii m
th nht. Mi ln lp li s ci thin chnh xc ca d liu gii m. D liu c x l
trong vng lp da trn c s block-by-block. Kch thc ca khi c th thay i
t 40 n 5114 bit, bao gm c 2 gi tr ny. Vi s lng d liu nh hn kch thc
ti thiu th cn phi chn vo cc bit gi c th t c kch thc ti thiu.Hnh 2.6
B gii m TurboLu = cc gi tr u tin i vi tt c cc bit thng tin u12eL=
thng tin t b gii m 1 vo b gii m 221eL = thng tin t b gii m 2 vo b
gii m 1( ) pcL r = thng tin kim tra (parity)GVHD: Lm Hng Thch SVTH:
Nguyn Th Thu Hng 30 N TT NGHIP( ) scL r= thng tin h thng
(systematic)2.4M hnh knh fading v dung lng h thng MIMO trong knh
truyn 2.4.1M hnh knh fadingXut pht t l do c rt nhiu tham s lin quan
trong qu trnh truyn dn trong mi trng v tuyn di ng, nn s thun tin hn
nhiu nu p dng k thut thng k m t s thay i ca tn hiu. Trong mt h thng
bng hp, tn hiu pht lun chim bng tn nh hn bng tn kt hp ca knh, bng
tn ny c nh ngha l di tn s m qu trnh fading knh l
tngng.Nghalmithnhphnphcatnhiuphtccngssuygim fading. Loi fading ny c
gi l fading khng chn lc hay fading phng. Mt khc nu di thng tn hiu
pht ln hn di thng kt hp knh, th cc thnh phn ph ca tn hiu pht vi phn
ph ln hn di thng kt hp b fading c lp. Ph tn hiu thu s b mo v s bin
i gia cc thnh phn ph ca tn hiu pht l khng ging nhau. Hin tng ny c
gi l fading chn lc theo tn s. Trong cc h thng bng rng, tn hiu pht
lun chu nh hng ca fading chn lc theo tn s.Chng ny cp ti m hnh
fading Rician v Rayleigh m t s thay i ca tn hiu trong mi trng a ng
bng hp. M hnh fading chn lc theo tn s cho h thng bng rng s c suy ra
bng cch coi bng tn rng l mt tp trc giao cc bng tn con.2.4.1.1
Fading RayleighXt qu trnh truyn dn 1 tn hiu n vi bin khng i. Trong
khu vc knh v tuyn di ng in hnh ta gi s rng sng trc tip b chn v my
thu di ng ch thu c sng phn x. Khi s lng sng phn x ln, theo nh l gii
hn trung tm, 2 thnh phn vung gc ca tn hiu thu l qu trnh ngu nhin
Gaussian khng tng quan vi tr trung bnh 0 v phng sai 2s. Kt qu l ng
bao ca tn hiu thu mi GVHD: Lm Hng Thch SVTH: Nguyn Th Thu Hng 31 N
TT NGHIPthi im c phn b xc sut Rayleigh v pha ca n phn b ng dng
trong khong p v p . Hm mt phn b ca phn b Rayleigh cho bi cng thc:(
)2 2/ 2200 0ssae ap aa '
