Tng quan v mng cm binI. c im ca mng cm binMng cm bin l mt mng thng minh. N kh nng cung cp truy nhp thng tin mi lc, mi thi im bng cch thu nhp, x l, phn tch v ph bin d liu.Mt mng cm bin cho php thit b trong mng: 1) Thu thp thng tin2) X l thng tin, 3) Gim st an ton ca mi trng m n ng dng k c trong lnh vc dn s v qun s.Mi mng cm bin tp hp nhiu nt cm binPhn cng ca mt thit b mng cm bin gm c 5 thnh phn: b phn cm nhn, b vi x l, b nh, phn cung cp in v phn thu pht.Mi thit b c kh nng tnh ton v giao tip vi mi trng, thch ng vi tng ng dng.mt c s h tng mng dy c s dn n mt mng cm bin hiu qu hn, cung cp chnh xc hn v c tng nng lng ln hn sn cII. u im thit b mng cm bin c chi ph thp, nng lng thp, a chc nng v thu nh v kch thc, kh nng di ngNh vo s lng ln nn mng cm bin c tin cy, chnh xc, linh hot, chi ph ph hp v d dng trin khai v c qun l bi con ngiIII. ng dng ca mng cm binmng cm bin thng minh c kh nng gim st v pht hin nhng tnh hung xu, nhng du hiu lin quan nh ng t, l lt, m mu khng b v rt nhiu lnh vc khc ... nhng vn m mng khng dy thng thng khng gii quyt c. 1 s ng dng c th : Mng cm bin c trin khai phn tch mt a im t xa (chuyn ng ca mt cn lc xoy, pht hin chy trong mt khu rng ); Cm bin gn vo xe taxi trong khu vc th, thnh ph nghin cu iu kin giao thng v quy hoch cc tuyn ng c hiu qu; Mng cm bin khng dy gip xc nh a im dng xe; Mng cm bin khng dy gim st an ninh ti mt trung tm mua sm, nh xe hay mt a im no khc; Mng cm bin khng dy dng pht hin v theo di mc tiu trong qun s;

Mng cm bin c th lm tng kh nng cnh bo v kh nng xy ra mt v khng b

IV. MNG CM BIN PHN CP

Hnh 4.1: Cu trc mng cm bin phn cpHnh 4.1 m t mi quan h gia cc cp. Cao nht l headquaters ( nt sink) sau l n commanders ( nt cha m) tip theo l n general ( nt trng nhm). Cui cng l soldiers ( nt con).Cc nt con trong cng 1 nhm general khng th truyn d liu cho cc nt trng nhm khc nhm ca mnh. Nhng cc nt con c th lin lc vi cc nt con khc ca nhm khc c th truyn d liu cho nt trng nhm ca nhm .Lnh t cp cao nht s truyn xung ln lt thng qua cc cp gim dn. V d liu s truyn ln ngc li, truyn t cp thp nht cho n cp tip theo.V. Nhng kh khn i vi mng cm bin Gii hn v nng lng , cng sut tnh ton, ngun lc truyn thng ca mt nt cm bin i hi vic s dng mt s lng ln cc nt trong mt vng rng ln. Duy tr hot ng ca mng cm bin v xy dng mt m hnh mng thng minh l hai thch thc chung, nhng thch thc c bn l: Cu trc trong mng cm bin thay i thng xuyn( thay th, b sung thit b ph hp vi yu cu ). Mng cm bin s dng m hnh im- a im, khc vi cc mng khc l im - im. Mng cm bin rt hn ch v nng lng, kh nng tnh ton v phn cng ( do s lng thit b ln nn vic np nng lng mt nhiu thi gian) Cc thit b trong mng cm bin rt d b hy hoi/cht ( do c tnh di ng ca n, chu nhiu nh hng ca mi trng ) Thit b mng cm bin khng c chung chun nhn dng ton cu v s lng l rt ln. Mng cm bin trin khai vi s lng nt ln s dn n xung t (va chm v mt truyn thng) v gy tc nghn mng, tng tr. trnh va chm mng cm bin c quy nh phm vi truyn dn v thi gian truyn dn ring. Vi cc thit b ty bin c kh nng di ng yu cu h thng c kh nng nhn dng v phn ng vi s di chuyn ca mc tiu. S thay i ca iu kin mi trng yu cu h thng c nhng thay i thch hp hn.VI. YU CU CHUNG CA MNG CM BIN- S lng thit b cm bin ln: do gi thnh r, kch thc nh . hot ng hiu qu cn c s phn cp, phn cm - S dng nng lng thp: thit b hot ng vng c iu kin khc nghit nn hn ch vic np nng lng nn cn phi tiu th mc ti thiu - S dng hiu qu b nh nh: ti u kch thc ca thit b - Tp hp, thu thp d liu: trnh tnh trng tc nghn cc ch cm cn c kh nng tng hp v x l d liu c th truyn tip n nt khc - T t chc mng: mng cm bin c h thng d phng v t cu hnh m bo hot ng lin tc khi c hng hc hoc thay th, b sung thit b - X l tn hiu hp tc( khc vi mng Manet) : d on v pht hin bin c. Cn c tch hp d liu t nhiu cm bin - Kh nng truy vn: C 2 loi a ch trong mng cm bin l data-centric (trung tm d liu) vi truy vn c gi ti nhng vng c bit trong mng v address-centric (trung tm a ch) vi cc truy vn c gi n mt nt ring bit. VII. Tim nng ca mng cm bin so vi mng Manet Nng cao chnh xc: do c tng hp, x li nhiu loi thng tin (d liu a chn, d liu m thanh, hnh nh phn gii cao). D liu a chn, d liu m thanh, hnh nh phn gii cao). Hot ng bnh thng khi mt vi nt c th b hng. Kh nng chu li cao hn vi mc d phng cao. Ci thin cc truy cp t xa n mng cm bin bng cch cung cp cc nt sink (trm gc) kt ni vi cc mng khc, chng hn nh mng Internet, s dng kt ni khng dy bng rng C kh nng kt ni cc thit b ri rc li vi nhau tit kim nng lng. C th lm vic trong mi trng khc nghit v khng cn gim st C th t ng thch ng vi cc s thay i ca mng. VIII. Cch hot ng ca mng cm bin ty bin Tp cc nt cm bin to thnh 1 mng tm thi, khng c cu trc h tng nh cc trm c s. S dng thu pht tn s khng dy (RF) v giao tip vi nhau thng qua lin kt khng dy a chng. C kh nng nh tuyn truyn d liu cho nt ln cn Do lin tc c s thay i trong cu hnh mng ( s hng hc, b sung thit b,) cn c giao thc nh tuyn c ng i tt nht gia hai nt truyn thng Vi nhng cm bin c kch thc nh, phi hp gia chng vi nhau nhm cm nhn trn mt vng rng ln m vn tiu th nng lng t th chng cn c phn cm. Mi cm gn (ch nh) mt ch cm qun l cc cm bin trong cm. Li th ca cc ch cm (cluster head) l:+ Cm bin cho php xp nhm s tng tc cc b ca chng c hiu qu t c mc tiu tng th.+Kh nng m rng.+Ci thin tnh bn vng.+S dng ti nguyn hiu qu hn.+Nng lng tiu th thp hn+Kt ni bn vng v phn vng mng.

Hnh 8 : Cu trc chung ca mng cm binC 3 lp: lp d liu, lp vt l, lp dch v. Lp dch v th khng gii hn lng dch v, giao thc nh tuyn, s ph bin d liu v tp hp d liu. Lp vt l bao gm cc nt vt l. Cc nt l nt sink, nt con, nt trng nhm, nt cha m- Nt sink a truy vn ti ton b mng cm bin hoc hng ti mt vng c th ty thuc vo loi truy vn s dng. Khi nt con gn i tng cm nhn, v d nh pht hin mt thay i v nhit , v tr , tc th chng s truyn d liu ny n cc nt con ln cn. V mi nt con kt ni t nht vi mt nt trng nhm .Nhim v ca cc nt trng nhm l x l v tng hp d liu v truyn n n cc nt sink thng qua nt cha m. l do nt trng nhm nhn c nhiu gi d liu t cc nt con ca n. Do , nt trng nhm c nhim v x l v lc d liu ny nh thng tin. - Khong cch gn gia cc nt cng gip tit kim nng lng bng cch gim bn knh truyn cho mi nt.

IX. S dng trung tm d liu thay trung tm a ch Do s lng ln v lun c s thay i thit b nn khng cn c a ch ring bit cho tng nt .Cc ng dng trung tm d liu tp trung vo d liu do cm bin to ra. V vy, thay v gi truy vn n cm bin #45, truy vn s c gi ti khu vc #6 c bit n t cc thit b nh v ton cu Global Positioning System (GPS) trong nt cm bin. tng s dng GPS d dng nh v cm bin l rt quan trng khi ph bin gi d liu, nh chng ta c th gi truy vn mt khu vc c th nh s gip ca GPS c nhng trong mt s nt cm bin. Nhng GPS c th nhm khi cc nt c v tr trng ln nhau, hoc cc nt gn nhau c cng kt qu GPSX. Tng hp v phn phi d liuTng hp l hu ch cho nhng l do sau: Tng s tun hon ca tri thc Tng mc chnh xc D phng d liu b p cho cc nt cm bin hng Phn phi d liu: c 2 cch + Truy vn mt- mt: nt sink gi 1 truy vn v nhn li c 1 phn hi t truy vn ny + Truy vn mt- nhiu: nt sink gi 1 truy vn v nhn li c lin tc phn hi t truy vn nyNhn xt: tuy cch 2 tn nhiu nng lng , d liu nhng thng tin chnh xc . C th ng dng rt ln vo thc t ( kim sot my bay, kim tra ch xe cn trng,.. )-Li th ca vic s dng cm bin l kh nng duy tr kt ni trong trng hp chuyn ng. Cc b cm bin ny l rt nh nn chng d b h hng khi b di chuyn. Do , mng cm bin nn duy tr mc kt ni ngay c khi mt s cm bin ca chng b chuyn i. V d, cm bin nm trong mt khu rng c th b tn hi vi bt k loi di ng no (con ngi, ng vt, ma,).

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