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Transcript of NGUYỄN VĂN CHÍNH TRUYỀN THÔNG KẾT HỢP · PDF fileVÔ TUYẾN NHẬN...

  • B THNG TIN V TRUYN THNG

    HC VIN CNG NGH BU CHNH VIN THNG

    **************************

    NGUYN VN CHNH

    TRUYN THNG KT HP TRONG MI TRNG

    V TUYN NHN THC: CI THIN V

    NH GI HIU NNG CA MNG TH CP

    Chuyn ngnh : K thut vin thng

    M s: 62.52.02.08

    TM TT LUN N TIN S K THUT

    H NI - 2017

  • Cng trnh hon thnh ti:

    Hc vin Cng Ngh Bu Chnh Vin Thng

    Ngi hng dn khoa hc:

    1. PGS.TS. V Nguyn Quc Bo

    2. TS. Nguyn Lng Nht

    Phn bin 1:

    Phn bin 2:

    Phn bin 3:

    Lun n s c bo v trc hi ng chm lun n ti:

    Hc vin Cng Ngh Bu Chnh Vin Thng,

    Vo lc: gi ngy thng nm 2017

    C th tm hiu lun n ti:

    Th vin Quc gia

    Th vin Hc vin Cng Ngh Bu Chnh Vin Thng

  • 1

    M U

    Cng ngh v tuyn nhn thc (cognitive radio - CR) ra i gip ci thin

    hiu sut s dng ph tn bi n cho php cc dch v v tuyn c th s dng

    chung di ph. Bn cnh v tuyn nhn thc, truyn thng a chng cho php

    h thng m rng vng ph sng cng nh ci thin cht lng tn hiu trong

    vng ph sng . Tuy nhin, nhc im ca truyn thng a chng l hiu

    sut s dng ph tn thp. gii quyt vn ny, cng ngh v tuyn nhn

    thc l mt s la chn tt nht. Phng thc truyn dng nn c u im l

    cho php mng s cp v mng th cp c th ng thi truyn nhn d liu

    min l can nhiu ca mng th cp khng c ln hn mc chu ng ca

    my thu s cp. thc hin iu ny, my pht th cp thng phi iu

    chnh cng sut ph thuc vo li knh truyn can nhiu t my pht th

    cp n my thu s cp dn n vng ph sng ca mng th cp thng gii

    hn v vic m bo cht lng dch v QoS ca h thng th cp l mt vn

    th thch.

    Lun n nh hng gii quyt bi ton nng cao hiu nng ca mng th

    cp trong khi vn m bo mc can nhiu cho mng s cp bng cch s dng

    cc k thut tin tin lp vt l nh: truyn chuyn tip, truyn hp tc,

    truyn thch nghi v m ha khng gian.

    MC TIU, I TNG V PHM VI NGHIN CU

    Mc tiu nghin cu:

    Xy dng cc m hnh mng truyn thng kt hp v chuyn tip hiu qu

    cho mng th cp: m bo QoS v m rng vng ph sng. xut cc

    phng php mi cho php phn tch hiu nng ca cc m hnh mng xut.

    p dng cc k thut ci thin hiu nng lp vt l: m khng gian thi

    gian, truyn thch nghi ci thin hiu nng ca mng th cp trong khi vn

    m bo thng tin ca mng s cp.

    i tng nghin cu

    Cc k thut kt hp: selection combining v maximal-ratio combining;

    Cc k thut truyn thch nghi gim nh hng can nhiu ln h thng s cp;

    Knh truyn fading: Rayleigh; Cc m hnh truyn thng hp tc: truyn

    la chn, truyn lp li, truyn gia tng;

    Cc giao thc x l tn hiu ti nt chuyn tip: amplify-and-forward,

    decode-and-forward, v coded cooperation;

    Cc k thut chn nt chuyn tip trong mng truyn thng hp tc;

    K thut truyn a chng s dng cng ngh MIMO.

  • 2

    Phm vi nghin cu:

    Thng tin v tuyn, mng truyn thng kt hp v k thut v tuyn nhn thc.

    Nhim v nghin cu

    nng cao hiu nng, m rng vng ph sng v cht lng dch v QoS

    ca mng th cp (Mng Cognitive radio) m khng nh hng n cht

    lng ca mng s cp; NCS phi thc hin cc nhim v sau:

    Mt l xut m hnh truyn thng kt hp s dng nhiu nt chuyn

    tip, nhng chn nt chuyn tip AF tt nht dng nn. Trong xem xt

    trong cc iu kin sau:

    * Xem xt n knh can nhiu t nt ngun v nt chuyn tip n nt

    thu s cp

    * Xem xt trn knh truyn Pha inh rayleigh c lp, khng ng nht

    * Xem xt n knh truyn trc tip t ngun n ch v k thut kt

    hp ti nt ch.

    Hai l xut m hnh chuyn tip a chng tin hnh ti u v tr nt

    chuyn tip DF dng nn. Trong xem xt trong cc iu kin sau:

    * Xem xt cng sut chu ng can nhiu ti a ca my thu s cp

    * Xem xt cng sut pht ti a ca my pht th cp

    Ba l ng dng m ha khng gian thi gian Alamouti vo trong mng v

    tuyn nhn thc dng nn trong trng hp mt chng v nhiu chng. Trong

    xem xt trong cc iu kin sau:

    * Xem xt cng sut chu ng can nhiu ti a ca my thu s cp

    * Xem xt knh can nhiu t my pht th cp n my thu s cp.

    Bn l ng dng iu ch thch nghi trong mi trng v tuyn nhn thc

    dng nn. Xy dng v gii bi ton ti u hiu sut ph tn, cc kt qu biu

    din di dng ng cho knh truyn fading Rayleigh trong xem xt trong

    iu kin knh can nhiu t my pht th cp n my thu s cp.

    Cu trc lun n Chng 1: Gii thiu v v tuyn nhn thc v truyn thng kt hp

    Chng 2: xut v nh gi hiu nng m hnh truyn thng kt hp

    hiu qu trong mi trng v tuyn nhn thc dng nn.

    Chng 3: nh gi hiu nng m ha khng gian thi gian Alamouti

    trong mi trng v tuyn nhn thc dng nn: mt chng v nhiu chng

    Chng 4: iu ch thch nghi trong mi trng v tuyn nhn thc

    dng nn: Ti u hiu sut ph tn.

  • 3

    CHNG 1. GII THIU V V TUYN NHN THC V TRUYN

    THNG KT HP

    Tm tt: Chng ny gii thiu nhng kin thc c bn lin quan n lun n l nhng khi nim c bn v tuyn nhn thc, truyn thng kt hp (MIMO o) v truyn thng kt hp trong mi trng v tuyn nhn thc. Mi quan h gia v tuyn nhn thc vi v tuyn thng minh, kin trc vt l vchc nng v tuyn nhn thc. Phn tch cc m hnh mng v tuyn nhn thc v cu trc mng v tuyn nhn thc.

    1.1 GII THIU

    Chng ny trnh by tng quan nhng vn c bn v v tuyn nhn thc, truyn thng kt hp v s kt hp truyn thng kt hp vi v tuyn nhn thc. Phn cui ca chng rt ra mt s nhn xt xut hng nghin cu nhm ci thin hiu sut s dng ph tn m vn m bo cht lng dch v QoS.

    1.2 V TUYN NHN THC

    1.2.1 S cn thit ra i v tuyn nhn thc

    Do vy nhu cu bc thit t ra i vi nn vin thng th gii l cho ra i mt h thng v tuyn nhn thc c kh nng s dng nhng khong trng trong di tn s. S xut hin ca v tuyn nhn thc cho php gii quyt c nhng kh khn trong vic s dng hiu qu ti nguyn tn s v tuyn.

    1.2.2 Khi nim v tuyn nhn thc

    Theo IEEE: V tuyn nhn thc l h thng pht/nhn tn s v tuyn m c thit k thng minh pht hin mt khong ph ang s dng hay khng, v nhy (hoc thot khi nu cn thit) rt nhanh qua mt khong ph tm thi khng s dng khc, nhm khng gy nhiu cho cc h thng c cp php khc.

    1.2.3 Mi quan h gia v tuyn thng minh (Software Defined Radio) v v tuyn nhn thc

    V tuyn nhn thc cn da trn v tuyn thng minh pht trin. Hay ni cch khc, v tuyn thng minh chnh l cng ngh li ca v tuyn nhn thc.

    1.2.4 Kin trc vt l ca v tuyn nhn thc

    B phn chnh ca h thng thu pht v tuyn nhn thc gm hai phn l phn cao tn (RF font end), v phn x l bng gc (baseband processing unit).

  • 4

    1.2.5 Chc nng v tuyn nhn thc

    H thng v tuyn nhn thc c bn chc nng chnh, l: Cm bin ph, Phn tch qun l ph, Qun l ph v chia s ph.

    1.2.6 M hnh mng v tuyn nhn thc 1.2.6.1 M hnh mng v tuyn nhn thc dng nn (underlay)

    Trong m hnh v tuyn nhn thc dng nn, mng th cp v mng s cp hot ng trn cng mt tn s trong my pht th cp phi iu chnh cng sut pht sao cho cng sut can nhiu nhn ti my thu s cp phi nh hn mt ngng quy nh trc, pI .

    1.2.6.2 M hnh mng v tuyn nhn thc dng chng chp (overlay)

    Trong m hnh ny, mng s cp v th cp hot ng trn cng bng tn vi gi nh rng hai mng phi trao i thng tin v hp tc ln nhau loi b/trch can nhiu gia hai mng bng cc k thut x l tn hiu phc tp.

    1.2.6.3 M hnh mng v tuyn nhn thc dng an xen (interweave)

    M hnh v tuyn nhn thc dng an xen l m hnh h thng th cp phi dng truyn nu h thng s cp truyn pht tr li hn ch gy can nhiu cho h thng s cp.

    1.2.7 Cu trc mng v tuyn nhn thc

    Mng v tuyn nhn thc c th tn ti hai dng c cu trc v khng c cu trc.

    Vi dng c cu trc, cc phn t mng c th giao tip vi nhau thng qua trm gc (hoc nt ch) tn s bn quyn hoc tn s khng bn quyn. Trong m hnh mng, c th c phn t qun l ph (Spectrum broker), gip trao i thng tin tn s (l ph) gia cc h thng v tuyn nhn thc.

    Vi dng khng c cu trc (ad-hoc networks), cc phn t mng kt ni vi nhau thng qua kt ni ad-hoc. M hnh mng khng c cu trc thng c s dng trong mng cm bin, thu thp thng tin.

    1.3 M HNH KNH CA H THNG TRUYN THNG TRC TIP

    1.3.1 M hnh c bn

    S D

    Hnh 1.8: M hnh knh ca h thng truyn thng trc tip

  • 5

    1.3.2 Cc k thut phn tp s dng trong mng v tuyn nhn thc 1.3.2.1 Cc phng php t hp phn tp

    Cho n nay, k thut phn tp c chia lm bn loi c bn:

    Kt hp la chn (Selection Combining)

    Kt hp chuyn mch (Switching Combining)

    Kt hp li cn bng (Equal-Gain Combining)

    Kt hp t s cc i (Maximal Ratio Combining)

    1.3.3 K thut MIMO (Multi-Input Multi Output) 1.3.3.1 Khi nim MIMO

    nh ngha: MIMO l cng ngh truyn thng khng dy, trong c my pht v my thu u s dng nhiu anten.

    1.3.3.2 u nhc im ca k thut MIMO

    Vic s dng nhiu anten trong h thng MIMO cho php: i) ci thin hiu nng di dng li phn tp ca h thng v ii) nng cao dung lng ca h thng (truyn nhiu lung d liu).

    1.4 TRUYN THNG KT HP

    1.4.1 Truyn thng chuyn tip

    Hnh 1.10 M hnh h thng truyn thng chuyn tip a chng

    1.4.2 K thut MIMO o (Hay cn gi l truyn thng kt hp) 1.4.2.1 L do ra i MIMO o

    Cng ngh MIMO kh p dng trong cc thit b di ng cm tay v mng cm bin khng dy vi nng lng v nng lc tnh ton gii hn.

    1.4.2.2 Khi nim MIMO o

    H thng cho php cc u cui di ng ch s dng mt anten duy nht trong mi trng a ngi dng, c th chia s v s dng chung anten vi nhau, to ra mt b pht gm nhiu anten o t c s phn tp khng gian nh h thng MIMO. H thng nh vy gi l truyn thng kt hp hay l h thng MIMO o.

  • 6

    1.4.2.3 M hnh h thng

    Hnh 1.11 M hnh c bn ca h thng truyn thng kt hp

    M hnh c bn ca h thng truyn thng hp tc bao gm mt nt ngun (S), mt nt chuyn tip (R) v mt nt ch (D).

    1.4.2.4 Mt s k thut x l tn hiu trong truyn thng kt hp.

    Khuch i v chuyn tip v Gii m v chuyn tip

    1.4.2.5 So snh k thut chuyn tip AF v DF

    V mt k thut, kiu AF n gin hn nhng n i hi nt chuyn tip c nhiu b nh lu tr cc mu tn hiu thu trc khi khuch i v chuyn tip. Trong khi , kiu DF li c u im l thch hp cho cc h thng s c s dng m ha.

    1.5 TRUYN THNG KT HP TRONG MI TRNG V TUYN NHN THC

    1.5.1 Phn tch u v n