1

Chng trnh Qun L Hc Sinh ng dng cng ngh RFID

CHNG 1:TNG QUAN CNG NGH RFID

Khong chc nm tr li y chng ta a bt u bt gp nhiu ng dng cng ngh RFID trong thc tin cuc sng hng ngy. n gin nht c th thy, mi khi chng ta vo chui siu th ca Walmart mua hng,khi ra ta ch cn a tng sn phm li gn mt thit b c v sau thc hin tr tin. chnh l mt h thng RFID in hnh m a c Walmart trin khai cho chui siu th ca h trn khp th gii.T y chng ta c th thy mt iu rng, cng ngh RFID a gip chng ta tin li hn rt nhiu trong cuc sng hng ngy. By gi chng ta hy cng i tm hiu mt h thng RFID ni chung hiu r hn hot ng ca n.

1.1. Lch s cng ngh RFID

RFID khng phi l mt khi nim mi ,m lch s ca n a bt u t th chin th II. Thi cc nc nh M, Anh, c v Nht Bn a s dng radar xc nh my bay i vo lnh th ca h bi vy vic nhn dng my bay i phng a tr thnh mt nhim v ti quan trng. Nhn thc c vn ny, ngi c a tm ra c rng nu nh cc phi cng ln vng my bay ca h trong khi quay tr li cn c th n s thay i tn hiu phn x tr li v ci ny c th coi nh l h thng RFID th ng u tin. Bn cnh ,Watson-Watt a pht trin c vic nhn dng tch cc i tng bn/k th u tin hay cn c gi l h thng IFF cho nc Anh trong cng thi gian .

Nm 1973 Mario W. Cardullo a c nhn bng sng ch cho vic ch to thnh cng th tch cc RFID vi b nh c th ghi c. V cng trong nm c bit California, mt doanh nhn c tn l Charles Walton a c nhn gii thng nh vic sng ch ra cc transponder th ng m ca m khng cn s dng ti cha kha. Thi k ny chng kin cc cng ty pht trin cc h thng tn s thp vi cc transponder nh v n vn cn c s dng trong ngnh chn nui gia sc cho ti ngy nay. Cc h thng 125 kHz a c thng mi ha trong khong thi gian v t cc cng ty bt u tin ti cc tn s cao hn c th s dng c ti mt vi vng trn th gii.

Cc cng ty ln bt u nhn thy tm quan trng ca RFID l vo nhng nm chn mi ca th k trc,c th l IBM a pht trin v sng ch ra cc h thng UHF RFID. Tuy nhin na u nhng nm chn mi c th c coi l qu trnh hc tp cng ngh bi cc sn phm sn xut ra c gi thnh rt cao v khng ccc tiu chun c th no.

Nm 1999 c th coi l nm vng ca cng ngh ny khi m cc t chc nh : t chc quc t EAN, Gillette, Uniform Code Council v P&G a to ra mt qu cho vic thnh lp trung tm Auto-ID ti hc vin cng ngh MIT. Hai gio s ca MIT l Sanjay Sharma v David Brock, l nhng ngi u tin ngh ra vic a cc m s ln trn cc th RFID cho bit gi tr ca chng v iu ny c th lm thay i cch thc ng dng cng ngh ny trong mt chui cung ng.Trong khong gia nhng nm t 1999 ti 2003 trung tm Auto-ID a nhn c s tr gip t hn mt ngn cng ty , cc nh cung cp RFID chnh v B Quc Phng Hoa K. Cc phng nghin cu c m ra nhiu nc v sau khng lu cng ngh a c cp php cho Uniform Code Council vo nm 2003 thc hin thng mi ha . i u trong vic ng dng cng ngh ny trong thc t c th k n cc tn tui ln nh Wal-Mart,Metro. Ngy nay cng ngh ny a c ng dng rng ri trong nhiu lnh vc nh ng dng vo vic chm cng ti cc cng ty, hay ng dng vo vic ghi nh ngun gc thy sn ng lnh xut khu,...V theo nhn nh ca nhiu chuyn gia th trong tng lai gn cng ngh ny vn lun l mt la chn ti u.

1.2. Cc khi nim c bn

Sng l mt dao ng vn chuyn nng lng t mt im ny ti im khc.Sng in t l sng c to ra bi cc electron chuyn ng v dao ng in t trng. Cc sng ny c th i xuyn qua mt s kiu cht liu khc nhau.

im c v tr cao nht trn mt sng c gi l mt nh sng, v im thp nht c gi l mt lm sng. Khong cch gia hai nh sng lin tip hoc hai lm sng lin tip th c gi l mt bc sng. Mt bc sng hon chnh ca mt dao ng sng c gi l chu k. V thi gian cn thit mt sng hon thnh mt chu k,c gi l chu k dao ng . S cc chu k trong mt giy c gi l tn s ca sng. Tn s c n v l hertz (k hiu Hz). V nu nh tn s ca mt sng l 1 Hz,th c ngha l sng ang dao ng vi tc mt chu k trn giy. Cc n v khc thng c dng l KHz (= 1,000 Hz), MHz (= 1,000,000 Hz), hoc GHz (= 1,000,000,000 Hz).

Hnh di y ch ra mt vi b phn ca mt sng.

Hnh 1.1 Cc thnh phn ca sng Cc sng v tuyn hay cc sng c tn s v tuyn (RF) l cc sng in t vi chiu di bc sng gia khong 0.1 cm v 1,000 km hoc l c tn s nm trong khong gia 30 Hz v 300 GHz.Ngoi ra cn c nhiu kiu sng in t khc nh : tia hng ngoi, tia t ngoi, tia gamma, tia x, v cc tia v tr.iu ch l qu trnh thay i cc c tnh ca mt sng v tuyn m ha mt vi tn hiu thng tin mang theo .Cng ngh RFID ch yu dng ba loi tn s l : tn s thp LF, tn s cao HF, tn s siu cao UHF .Cn loi tn s rt cao VHF th cha thy c h thng RFID s dng, do vy ti khng cp n y.

Tn s thp LF: l cc tn s nm trong khong gia 30 KHz n 300 KHz ,h thng RFID thng thng ch s dng cc tn s trong phm vi t 125 KHz ti 134 KHz.Cn vi mt h thng LF RFID in hnh th thng hot ng ti tn s l 125 KHz hoc l 134.2 KHz. H thng RFID hot ng ti tn s thp thng s dng cc th th ng, nn tc truyn d liu t th ti thit b c th l rt thp. Song tuy nhin, cc th tch cc LF cng c th c s dng bi cc nh cung cp. Ngy nay phm vi tn s LF c chp nhn s dng khp mi ni trn th gii.

Tn s cao HF:l cc tn s nm trong phm vi t 3 MHz ti 30 MHz, trong 13.56 MHz l tn s in hnh thng c s dng cho cc h thng RFID. H thng HF RFID thng s dng cc th th ng,nn c tc truyn d liu kh thp t th ti thit b c th. Ngy nay cc h thng HF c s dng rng ri, c bit l trong cc bnh vin (v n khng gy nhiu cho cc thit b y t ang hot ng khc). V c l do vy m phm vi tn s HF a c chp nhn s dng hu nh khp th gii.

Tn s siu cao UHF: l cc tn s nm trong khong t 300 MHz ti 1 GHz .H thng UHF RFID th ng thng hot ng ti tn s 915 MHz ti Hoa K v ti 868 MHz cc nc Chu u. Cn h thng UHF RFID tch cc hot ng ti tn s 315 MHz v 433 MHz.V v vy h thng UHF c th s dng c c hai loi th tch cc v th ng v c th t c mt tc truyn d liu kh nhanh gia th v thit b c th. Cc h thng UHF RFID hin ti a bt u c trin khai rng ri trong cc t chc chnh ph cc nc nh b quc phng M v cc t chc quc t, ... Tuy nhin phm vi tn s UHF vn khng c chp nhn s dng trn ton th gii. Di y hnh nh minh ha phm vi cc tn s m ta a ni trn

Hnh 1.2 Ph tn s v tuyn

By gi ta s ni thm v cc nguyn nhn gy nhiu cho sng in t.Ni chung, sng in t thng b nhiu t nhiu ngun khc nhau, song ch yu l cc ngun di y:

- Cc iu kin thi tit nh ma ,tuyt, ... Tuy nhin, nh a ni trc ,ngun nhiu ny t nh hng vi cc phm vi tn s LF v HF.

- S c mt ca mt vi ngun sng v tuyn khc chng hn nh cell phone, mobile radio,...

- Cc dng tnh in (ESD). ESD l mt lung dng in bt ng i qua mt cht liu trong tnh hung cht liu c s cch in di mc chun.Nu nh c mt s khc nhau ln v in p tn ti gia hai im trn cht liu, th cc nguyn t gia hai im ny c th tr thnh cc in tch v to thnh dng in.

Ngoi ra chng ta cng cn bit thm cc khi nim khc di y c lin quan n h thng RFID.

S xung t th : Mt reader ch c th lin lc c vi mt th ti mt thi im. Khi c nhiu hn mt th c gng lin lc vi reader, th lc xut hin hin tng c tn gi l s xung t th. Trong trng hp ny, p li truy vn t reader, nhiu th s phn hi cc tn hiu ca chng ti reader ti cng mt thi im. Reader cn thit phi lin lc sau vi cc th bng cch s dng mt giao thc c ng dng mt thut ton c bit. Thut ton m c s dng ha gii cc xung t th th c gi vi ci tn l cc thut ton chng xung t. Hin ti, hai kiu thut ton chng xung t di y l c s dng rng ri nht:

- ALOHA cho cc kiu tn s HF

- Tree Walking cho cc kiu tn s UHF

Bng cch s dng mt trong cc thut ton chng xung t trn, mt readerc th nhn dng c vi th trong vng c ca n vi mt chu k thi gian rtngn. Chnh v vy, m n khin cho ta c cm gic reader lin lc vi cc thgn nh l ng thi.

S xung t reader :Khi vng c (hoc l ca s c) ca hai hoc nhiu hiu t cc reader khc, gy ra nhiu tn hiu. Hin tng ny c gi s xung t reader. Tnh trng ny c th pht sinh nu nh cc anten hai reader ny c ci t theo cch thc no m dn n s can thip ph hoi ln nhau (v d nh, vng ph sng ca anten). Dn n mt h qu l, nng lng RF t mt trong cc anten ca mt reader s b loi ra ngoi v nng lng RF t mt trong cc anten ca reader khc. trnh vn ny, ta phi iu chnh li v tr cc anten ca cc reader sao cho anten ca mt reader khng i din trc tip vi anten ca reader khc. Nu nh khng th trnh khi vic c hai anten i din nhau, th gii php nn lm l phn chia khong cch hiu qu cho chng vng c ca chng khng chng ln nhau. Ngoi ra, hai anten ca cng mt reader cng c th to ra s chng lp ln nhau nhng n khng to s xung t reader, bi v nng lng i ti cc anten l cc chuyn dch vt l c thc hin bi reader theo cch m ch c mt anten hot ng ti mt thi im.

iu dn n, s khng c c hi hai hay nhiu anten ca reader ny pht ra cc tn hiu cng lc. Chng ta cng c th s dng k thut khc, c tn gi l TDMA, trnh s xung t reader.

Trong k thut ny, cc reader s c hng dn c ti cc thi im khc nhau ch khng phi tt c cng c mt lc. V nh vy, ch c anten ca mt reader l c hot ng ti mt thi im. Nhng c mtvn pht sinh vi phng php ny l, mt th c th c c nhiu hn mt ln bi cc reader khc nhau trong vng c chng cho ln nhau. Do , cn phi p dng mt vi c ch lc thng minh bi khi iu khin lc ra cc th a c c.

Kh nng c th: ca mt h thng RFID trong mt mi trng hot ng ph bin c th c nh ngha l kh nng ca h thng c thnh cng d liu t mt th c th. Kh nng c th ph thuc vo mt s cc yu t. cung cp kh nng c th tt th h thng RFID cn phi c thnh cng mt th t nht mt ln. m bo iu ny, th h thng nn c thit k sao cho s ln c mt th va ngay c khi th c li vi ln th vn c c hi tt mt trong s ln c thnh cng. Tc l xc sut thnh cng s cao hn.

1.3. Cc c im ca mt h thng RFID

Cc h thng RFID c th c phn bit vi nhau theo ba cch khc nhau da trn cc thuc tnh c trng di y:

- Tn s hot ng

- Phm vi c

- Phng php ghp ni vt l

1.3.1. Tn s hot ng

Tn s hot ng l thuc tnh quan trng nht ca mt h thng RFID. l tn s m ti , reader s truyn i cc tn hiu ca n. N gn kt cht ch vi mt thuc tnh in hnh, l c t mt khong cch xa. Trong hu ht cc trng hp,tn s ca mt h thng RFID c quyt nh bi khong cch cn thit vic thc hin c thnh cng .

1.3.2. Phm vi c

Phm vi c ca mt h thng RFID c xc nh l khong cch gia th v reader. T y ta thy mt h thng RFID c th c phn chia thnh ba kiu di y:

- Trc tip : l cc h thng c phm vi c thp hn 1 cm. Mt vi h thng LF v HF RFID thuc v nhm ny.

- Tm gn : l cc h thng c phm vi c t 1 cm ti 100 cm. a phn cc h thng RFID hot ng ti cc di tn LF v HF thuc v nhm ny.

-Tm xa : l cc h thng c phm vi c ln hn 100 cm. Cc h thng RFID ang hot ng trong di tn UHF v phm vi tn s vi ba thuc v nhm ny.

1.3.3. Phng php ghp ni

Vic ghp ni vt l m ta cp ti y l ni ti phng php s dng ghp t th ti anten). Da trn tiu ch ny, c ba kiu h thng RFID khc nhau di y:

- T trng : l cc kiu h thng RFID c bit ti nh l cc h thng c ghp ni theo kiu in khng. Mt vi h thng RFID LF v HF l thuc v nhm ny.

- in trng : l cc kiu h thng RFID c bit ti nh l cc h

thng c ghp ni theo kiu in dung. Nhm ny cng ch yu bao gm cc h thng RFID LF v HF.

- in t trng : Phn ln cc h thng RFID thuc lp ny cng c gi lcc h thng backscatter. Cc h thng RFID hot ng trong phm vi di tn s UHF v vi ba thuc v nhm ny.

1.4. Cc thnh phn h thng RFID

Mt h thng RFID l mt tp hp cc thnh phn nhm thc hin mt gii php RFID.

Ni chung mt h thng RFID bao gm cc thnh phn di y:

- Th : y l mt thnh phn bt buc ca bt c h thng RFID no

- Thit b c th: y cng l mt thnh phn bt buc

- Anten ca thit b c th : y l cng l mt thnh phn bt buc phi

c.Ngy nay mt s reader a c tch hp anten ln trn n,v vy kch

thc ca n a gim i rt nhiu.

- Khi iu khin : y l mt thnh phn quan trng. Tuy nhin hu ht cc reader th h mi u a tch hp thnh phn ny ln trn chng.

- Cc cm bin, b truyn ng ,b bo hiu : y l cc thnh phn ty chn, c s dng u vo v u ra h thng RFID.

- My ch v h thng phn mm :V mt l thuyt ,mt h thng RFID c

th hot ng mt cch c lp m khng cn ti thnh phn ny.Tuy nhin trong thc t, nu khng c thnh phn ny th h thng RFID gn nh v

gi tr.

- C s h tng truyn thng: Thnh phn quan trng ny l mt tp hp bao gm c mng c dy v khng dy v c s h tng kt ni ni tip, c th kt ni cc thnh phn a lit k pha trn vi nhau.

Di y l biu mt h thng RFID :

Hnh 1.3 Biu h thng RFID

By gi ta s i chi tit vo tng thnh phn ca h thng RFID.

1.4.1. Thnh phn th

Mt th RFID l mt thit b c th lu tr v truyn c c d liu ti

reader khng phi theo cch tip xc trc tip m bng cch s dng cc sng v tuyn. Cc th RFID c th c phn loi theo hai cch khc nhau. Di y l cch phn loi th nht, da trn c s th c cha ngun nng lng ngay trn bng mch th hay khng hoc da trn c s cc chc nng c bit m n cung

cp:

Th th ng

Th tch cc

Th bn tch cc (hoc bn th ng)

1.4.1.1. Th th ng

Kiu th RFID ny khng c ngun nui tch hp cng trn bng mch th (v d,pin),thay v vy n s dng nng lng c pht ra t reader lm ngun nng lng cho bn thn n hot ng v thc hin truyn d liu m n lu tr ti reader. Th th ng kh n gin v cu to v khng c cc b phn ri rc.V c l chnh v vy cc th th ng tn ti kh lu trong iu kin mi trng khc nghit.

i vi loi th ny, thc hin truyn thng tin gia th v reader th reader lun lun phi lin lc trc tin,tip sau mi ti lt th. V vy s hin din ca reader l bt buc th c th truyn c d liu ca n.

Th th ng thng thng nh hn so vi th tch cc v th bn tch cc. N c mt phm vi c kh a dng t 1 inch (=2.54cm) ti khong 30 feet (xp x 9 mt). C l bi vy m th th ng bao gi cng r hn th tch cc hay th bn tch cc.

Mt th th ng bao gm cc thnh phn chnh di y:

Thnh phn vi chip

Thnh phn anten

Di y l hnh nh minh ha cc thnh phn th th ng trong thc t:

Hnh 1.5 Cc thnh phn ca th th ng

Cn tip theo y l mt s hnh nh thc t v cc th th ng ca mt vi hng sn xut ln khc nhau:

Hnh1.7 Cc th 2.45 GHz ca hng Alien Technology

Hnh1.8 Cc th 915 MHz ca hng Intermec Corporation

1.4.1.1.1. Thnh phn vi chip

Mt vi chip ca th th ng bao gm cc khi nh ch ra hnh v di y:

Hnh 1.9 S cc khi ca vi chipKhi Power control/rectifier thc hin chuyn i ngun in xoay chiu thu c t tn hiu pht ra anten ca reader thnh ngun in mt chiu.Chnh ngun in mt chiu ny s cung cp nng lng ti cc thnh phn khc ca vi chip. Xung t khi Clock Extractor thc hin tch xung tn hiu t tn hiu thu c do anten ca reader pht ra. Sau khi Modulator s iu ch tn hiu nhn c.Thng tin m th tr li truyn ti reader c nhng vo bn trong tn hiu a c iu ch.B nh ca vi chip c s dng lu tr d liu. B nh ny thng c chia thnh cc phn (bao gm cc khi hoc l cc trng). y ta cn ch n thut ng addressability ,ngha l kh nng nh a ch (c hoc ghi) cc v tr b nh ring l ca mt vi chip. Mt khi b nh ca th c th lu tr c nhiu kiu d liu khc nhau,chng hn nh mt phn ca i tng d liu c s dng nhn dng th, cc bit kim tra tng (v d, cyclic redundancycheck [CRC]) kim tra chnh xc ca d liu a c truyn,...

1.4.1.1.2. Thnh phn anten

Anten ca th c s dng a tn hiu thu c t reader thnh nng lng cho th ,phc v cho vic gi hoc nhn d liu ti reader.Anten ny c gn tip xc vt l vi vi chip ca th. Trong thc t c rt nhiu cch thit k anten,tuy nhin chng ta cn phi ch rng chiu di ca anten t l trc tip vi chiu di bc sng hot ng ca th.Ngoi ra cn c mt khi nim na cng rt quan trng , l lng cc (dipole). Mt anten lng cc c th l mt dy in thng (v d,vi cht liu l ng) b t qung ti im gia. Chiu di tng cng ca mt anten lng cc bng mt bc sng ca tn s c s dng ti u ha nng lng chuyn t tn hiu ca anten reader ti th. Vi mt anten lng cc kp (dual dipole) th n bao gm hai lng cc, nn c th gim i rt nhiu tnh nhy cm thng hng ca th .Chnh v vy m, reader c th c th ti nhiu hng khc nhau.Cn mt lng cc gp (folded dipole) l bao gm hai hoc nhiu dy in thng kt ni song song v mi ci c chiu di bng na chiu di bc sng (ca tn s c s dng). Khi hai dy c ni li, th kt qu to ra mt lng cc gp-2 dy.Tng t nh vy ba dy kt ni song song s to ra mt lng cc gp-3 dy. Chiu di anten ca th thng ln hn rt nhiu so vi microchip ca th, vdo n quyt nh n kch thc vt l sau cng ca th. Ngoi ra c mt vi thng s ta cn ch khi thit k th:

Khong cch c th c tnh t reader

Hng nhn bit th so vi reader

1.4.1.2. Th tch cc

Cc th RFID tch cc c sn mt ngun nng lng trn bng mch th (v d nh c pin km theo;hoc l dng ngun nng lng khc) v cc b phn in t thc hin cc chc nng c bit. Mt th tch cc s dng ngun nng lng trn bng mch th ca chnh n truyn d liu ca n ti reader. N khng phi cn n nng lng pht ra t reader truyn d liu. Cc b phn in t trn bng mch th c th bao gm b vi x l, cm bin, v cc cng vo/ra. V d,cc thnh phn in t ny thc hin o mt khong nhit no v sinh ra d liu v gi tr nhit trung bnh.Sau chng s s dng d liu ny quyt nh cc tham s khc chng hn nh ngy kt thc ca mt hng c gn th .Ri tip th c th truyn thng tin ny ti reader. Chng ta c th hnh dung th tch cc ging nh mt chic my tnh khng dy cng thm vi vi thuc tnh khc (v d, c th bao gm thm mt cm bin hoc mt tp hp cc cm bin).

Trong giao tip truyn thng tin gia th v reader, th th lun lun phi thc hin lin lc trc tin, tip sau mi ti phin reader. Bi vy s hin din ca reader khng cn thit cho s truyn i ca d liu, mt th tch cc c th pht i d liu lu tr trong n ti cc khu vc xung quanh ngay c khi khng c reader. C l v vy m kiu th ny cng c gi l mt b pht tn hiu. Khong cch c th ca mt th tch cc c th l 100 feet (xp x 30.5 mt) hoc ln hn.

Mt th tch cc bao gm cc thnh phn:

Vi chip

Anten

Ngun nng lng nui th

Cc thnh phn in t

Do cc thnh phn vi chip v anten ca th tch cc cng ging vi th th ng nn ta s khng ni ti y.By gi ta ch ni qua v hai thnh phn cn li l khi ngun v cc thnh phn in t.1.4.1.2.1. Khi ngun

Tt c cc th tch cc u c mang mt ngun nng lng trn n (v d, c mt pin nh km theo) cung cp nng lng ti cc thnh phn in t v n thc hin truyn d liu i. Nu nh s dng mt pin lm ngun nng lng , th mt th tch cc c th s dng c t nht khong t 2 ti 7 nm ph thuc vo bn ca pin. Mt trong nhng nhn t quyt nh bn ca pin l tc truyn d liu ca th. V d, gi thit rng mt th tch cc c ch to mc nh l c thc hin truyn mt ln sau vi giy. Nu nh bn tng n ln,tc l thit lp c truyn mt ln sau mt vi pht thm ch l mt vi gi,th bn a lm cho tui th s dng pin lu hn. Ngoi ra, cc cm bin nm trn bng mch th v cc b x l tiu th nng lng t cng c th gp phn lm cho tui th ca pin ngn i.

1.4.1.2.2. Cc thnh phn in t

Cc thnh phn in t nm trn bng mch th cho php th hot ng nh mt b pht tn hiu (transmiter), v ty theo la chn c th m n c th thc hin c cc chc nng c bit chng hn nh vic tnh ton, hoc hot ng nh mt cm bin,...Thnh phn ny cng c th cung cp thng tin cho vic kt ni vi cc cm bin bn ngoi. Cho nn, ty theo kiu cm bin gn vo, m th c th thc hin c rt nhiu cc chc nng cm bin. Ni chung, phm vi cc chc nng ca thnh phn ny l khng gii hn. Ta cn ch rng khi s cc chc nng tng nn th kch thc vt l ca phn ny tng nn ,v v vy kch thc th cng tng ln. Tuy nhin iu ny hon ton c th chp nhn c vi cc th tch cc . V vy m, cc th tch cc c th trin khai ti mt phm vi rng cc ng dng hin nay.

1.4.1.3. Th bn tch cc (hoc th bn t ng)

Cc th bn tch cc cng c mt ngun nng lng nm trn n v c km thm cc thnh phn in t thc hin cc chc nng c bit. Ngun nng lng nm trn bng mch th cung cp nng lng cho cc hot ng ca th. Tuy nhin, truyn d liu i, th bn tch cc phi s dng nng lng pht ra t reader.y l mt c im ging vi th th ng. V vy kiu th ny cng c gi di ci tn khc l th c tr gip bi pin. Trong vic giao tip truyn thng tin gia th v reader, th reader lun lun phi thc hin lin lc trc tin, tip sau mi ti phin th. Cng c cc c im tng t nh trn l cc th bn th ng.

Vy ti sao li dng th bn th ng m khng dng th th ng ? L bi v th bn tch cc khng s dng cc tn hiu ca reader kch thch bn thn n nh cc th th ng, v n c th c c t mt khong cch xa hn so vi th th ng. V cng bi l do cc th bn th ng c th t kch thch chnh bn thn n . Do vy, ngay c khi i tng c gn th ang di chuyn vi mt tc ln,th d liu trn th vn c th c c khi ta s dng th bn th ng (hoc bn tch cc).

Cc th bn tch cc 2.45 GHz ca hng Alien Technology

Cc th bn tch cc 915 MHz/2.45 GHz ca hng TransCore

Ngoi cch phn loi trn cn c cch phn loi da trn c s v vic h tr kh nng ghi li d liu nh di y :

Ch c (RO)

Ghi mt ln ,c nhiu ln (RW)

c, ghi (WORM)

Ta cn ch rng c hai loi th th ng v tch cc u c th l RO,

WORM, v RW.Di y ta s i qua chi tit hn mt cht v cch phn loi ny.

1.4.1.4. Th ch c

Mt th RO ch c th lp trnh mt ln trong sut thi gian n tn ti. D liu c th c burn vo bn trong th ti nh my trong sut giai on ch to. hon thnh ci ny,cc cu ch ring l trn vi chip ca th c burn vnh cu bng cch dng mt chm laser c u nhn. Sau khi xong cng on ,th d liu s khng th ghi ln na ln th trong sut thi gian tn ti ca n. C l do vy m loi th ny cn c tn gi khc l factory programmed (c ngha l , c lp trnh bi nh sn xut). Nh sn xut th thc hin a d liu ln trn th,cn ngi dng th thng thng s khng c bt c iu khin no trn n. Kiu th ny kh thch hp cho cc ng dng nh, nhng khng thc t khi ch to s lng ln hoc khi d liu trn th cn c ty chnh da trn c s ng dng trin khai.

1.4.1.5. Th ghi mt ln c nhiu ln

Mt th WORM c th c lp trnh hay ghi li mt ln, thng thng vic ny s khng phi c thc hin bi nh sn xut m bi ngi dng th ti thi im h thc hin cng on to th. Trong thc t ,cc th loi ny thng ch c ghi vi mt s ln c nh (khong 100 ln) ! Nu nh d liu ghi ln th vt qu s ln quy nh , th th c th b h hng vnh vin.

y l kiu th c gi c phi chng c th thc hin vi s lng ln v c tnh bo mt d liu cao,c l vy m n l kiu th c s dng thnh hnh nht trong cc nghip v kinh doanh ngy nay.

1.4.1.6. Th ghi c

Mt th RW c th c lp trnh li hay l ghi li nhiu ln. Thng thng, con s ny nm trong khong gia 10,000 v 100,000 ln v c th hn na! Kh nng ghi ny a ra mt c trng to ln , l d liu c th c ghi hoc bi reader hoc bi chnh bn thn th (trong trng hp l cc th tch cc). Th RW thng c cha mt b nh Flash hoc FRAM lu tr d liu ca n. Bo mt d liu l mt th thch kh ln cho loi th ny. Ngoi ra, chi ph thc hin ch to chng cng kh t . C l v vy nn cc th RW khng c s dng rng ri trong cc ng dng ngy nay.

1.4.2. Thit b c th (reader)

Mt RFID reader l mt thit b cho php c hoc ghi ti cc th RFID thch hp. Hnh ng ghi d liu ln th bi mt reader c gi l cng on to th.Cng on to th cng vi vic gn th ln mt i tng no c gi l quy trnh a th i vo hot ng. Qung thi gian mt reader c th pht x nng lng RF c cc th c gi l chu trnh hot ng ca reader.

Reader l h thng thn kinh trung tm ca ton b phn cng h thng

RFID .Mt reader c cc thnh phn chnh di y:

B truyn tn hiu

B nhn tn hiu

B vi x l

B nh

Cc knh vo/ra cho cc cm bin, b truyn ng, v b bo hiu bn ngoi.

Khi iu khin

Khi giao tip truyn thng

Khi ngun

1.4.2.1 Khi truyn tn hiu

B truyn tn hiu ca reader c s dng truyn nng lng in xoay chiu v chu k xung thng qua anten ca chnh n ti cc th nm trong phm vi c ca n. y l mt phn ca b thu pht tn hiu, l thnh phn m chu trch nhim gi tn hiu ca reader ti mi trng xung quanh v nhn thng tin tr li t th thng qua anten ca reader. Cc cng anten ca reader s c kt ni ti thnh phn thu pht ca chnh n. Hin nay, mt vi reader c th h tr nn ti bn cng anten. iu c ngha l reader c th nhn dng c nhiu th ti cng mt thi im.

1.4.2.2 Khi nhn tn hiu

Thnh phn ny cng l mt phn ca khi thu pht. N nhn cc tn hiu tng t t th thng qua anten ca reader. Sau n gi cc tn hiu ny ti b vi x l ca reader, n s thc hin chuyn i sang nh dng s.

1.4.2.3 Khi vi x l

Thnh phn ny chu trch nhim thc hin cc giao thc ca reader lin lc vi tng loi th ph hp. N s thc hin gii m v kim tra li ca cc tn hiu tng t t b nhn tn hiu. Ngoi ra, n cn bao gm thm logic ty chnh lc mc thp v x l d liu c c t th.

1.4.2.4 Khi b nh

B nh c s dng lu tr d liu chng hn nh cc thng s cu hnh ca reader v danh sch cc th c th c c. Nu nh kt ni gia reader v thnh phn iu khin hoc h thng phn mm b ngt,th tt c d liu c c t th s b mt.

1.4.2.5 Cc knh vo/ra cho cm bin, b truyn ng, v b bo hiu bn ngoi

Cc reader khng phi lun hot ng c th ti tt c cc thi im. Xt cho cng, th cc th ch phi xut hin ti cc thi im chnh trong vng c ca n, v cng cho reader c rnh ri tit kim nng lng. Chnh v mc ch m ta phi s dng thnh phn ny. N cung cp mt kt cu c hc bt hay tt reader ph thuc vo cc s kin bn ngoi. Thng thng ta hay gp cc loi cm bin, chng hn nh mt cm bin chuyn ng hay mt cm bin nh sng, pht hin s hin din ca cc i tng c gn th trong vng c ca reader. Sau cm bin c th thit lp reader c th ny. Tng t, thnh phn ny cng cho php reader cung cp mt vi u ra ni b ph thuc vo mt vi iu kin no qua mt b bo hiu (v d nh, pht ra mt m thanh cnh bo).

1.4.2.6 Khi iu khin

Khi iu khin l mt thc th m cho php mt thc th bn ngoi, hoc l con ngi hoc l mt chng trnh my tnh, thc hin lin lc vi reader v iu khin cc chc nng ca n cng nh iu khin b bo hiu v b truyn ng c kt hp vi reader . Thng thng,cc nh sn xut s tch hp thnh phn ny vo bn trong bn thn reader (v d nh firmware). Tuy nhin, n cng c th c ng gi li nh mt thnh phn phn cng hoc phn mm ring bit m ngi s dng s phi mua n i km cng vi reader.

1.4.2.7 Khi giao tip truyn thng

Thnh phn giao tip truyn thng cung cp cch thc truyn thng tin ti

reader ,cho php n tng tc vi cc thc th bn ngoi, thng qua mt thnh phn iu khin , chuyn d liu lu tr trong n v nhn lnh v gi tr li cc phn hi tng ng. Thc th ny c cc c tnh quan trng khin n cn phi c ch to ra nh mt thnh phn c lp. Mt reader cng c th c kiu truyn thng ni tip ging nh giao tip mng my tnh ta thng thy. l kiu giao tip c kh nng ph bin thnh hnh nht trong cc kiu giao tip c th ca reader , tuy nhin cc phin bn reader sp ti y li ang pht trin cc giao din mng nh l cc chun c trng tin tin ca tng lai.

1.4.2.8 Khi ngun

Thnh phn ny thc hin vic cung cp nng lng nui cc thnh phn khc trn reader.

1.4.2.9 Phn loi thit b c th

Cng ging nh cc th, cc reader cng c th c phn loi bng cch s dng hai tiu ch khc nhau. Tiu ch u tin l da trn cch cung cp giao tip lin lc cho reader. Da trn ci ny, cc reader c th c phn loi nh di y:

Reader ni tip

Reader mng

Tip sau y ta s m t qua v cc kiu reader ny.

1.4.2.9.1 Thit b c th ni tip

Cc reader ni tip s dng mt lin kt truyn thng ni tip lin lc vi mt ng dng. Reader c lin kt vt l ti mt cng ni tip trn my tnh s dng mt kt ni ni tip RS-232 hoc RS-485. Ch rng c hai kiu kt ni ny u c mt gii hn v chiu di cp c th c s dng ni t reader ti my tnh. Vi kiu RS-485 cho php chiu di cp s dng di hn so vi kiu RS-232.

u im ca cc reader ni tip l c cc lin kt truyn thng ng tin cy hn so vi cc reader mng, bi v n khng ra cc hin tng mt gi tin nh trong reader mng . Do , vic s dng cc reader loi ny c khuyn khch gim thiu s ph thuc vo mt knh truyn thng.

Tuy nhin, nhc im ca cc reader ni tip l ph thuc vo chiu di ln nht ca cp c s dng ni t reader ti my tnh. Ngoi ra, bi v s lng cng ni tip thng c gii hn trn mt my ch, nn phi cn ti mt lng ln my ch c th kt ni c vi tt c cc reader ni tip.V cp nht firmware cho reader th ngi bo dng phi thc hin tin hnh vi tng reader. V vy i ng bo dng cng phi cn ti vi s lng nhiu. Ngoi ra, tc truyn d liu ni tip thng thp hn nhiu so vi tc truyn d liu mng. Tt c cc yu t ny c th dn n mt kt qu l , chi ph bo dng s cao hn v

thi gian ngng hot ng l ng k.

1.4.2.9.2 Thit b c th mng

Cc reader mng c th c kt ni ti mt my tnh bng cch s dng c mng c dy v mng khng dy. Trong thc t, loi reader ny c th c ci t vn hnh ging nh mt thit b mng thng thng m khng cn yu cu kin thc chuyn mn v phn cng. Tuy nhin cn phi ch rng, tnh nng gim st SNMP hin ang c s dng trn mt vi kiu reader mng. Do , phn ln cc reader ny khng th c gim st nh vi cc thit b mng chun c.

u im ca cc reader mng l n khng ph thuc vo chiu di ln nht ca dy cp c ni t reader ti my tnh. V n cng cn s lng my ch t hn so vi cc reader ni tip. Ngoi ra, firmware ca reader c th c cp nht t xa thng qua mng m khng cn ti bt c tip xc vt l no vi reader. Ci ny khin cho h thng d dng bo dng hn v cho thy n lc h thp chi ph ca mt h thng RFID.

Nhc im ca cc reader mng l cc lin kt truyn thng km tin cy hn so vi cc reader ni tip. V d, c th do l do no lin kt mng b trc trc trong khong thi gian ngn, khin cho mt gi d liu trong qu trnh chuyn d liu t reader v my ch. V c th dn n sai kt qu v d liu trn th . gii quyt vn ny, ni chung cc reader a c thm b nh trong lu tr d liu c c t th. Tnh nng ny d khng ti u nhng a phn no gim bt c hu qu gy ra do mt lin kt mng.

Tiu ch phn loi th hai c to ra da trn c s tnh di ng ca n, nh

ch ra di y:

Reader c nh

Reader cm tay

Di y ta s m t v cc kiu reader ny.

1.4.2.9.3 Thit b c th c nh

Cc reader loi ny c gn vo tng, cng, hoc mt vi cu trc ph hp trong vng c. Cc cu trc m trn reader c gn vo c th khng cn phi l tnh! V d , mt vi reader loi ny c th c gn ln cc xe nng hng. Tng t, ta cng c th gn cc reader ny bn trong cc xe ti giao nhn hng. Tri ngc vi cc th, cc reader khng chu c vi cc iu kin mi trng khc nghit. Do , nu nh chng ta ci t mt reader ngoi tri hoc trn cc i tng ang chuyn ng, th chng ta phi ch ti cc iu kin xung quanh n.

Cc reader c nh ni chung thng phi cn ti anten bn ngoi c th c c th. Mt reader c th cung cp ln ti bn cng anten bn ngoi.

Gi c ca cc reader c nh thng thp hn nhiu so vi cc reader cm

tay.Chnh v vy cc reader loi ny l kiu reader c s dng thng dng nht

hin nay.

Mt kiu reader c tn gi l reader agile c th hot ng trong cc tn s khc

nhau hoc c th s dng cc giao thc lin lc t th ti reader khc nhau. Ngy

nay cc reader agile l loi reader c nh thng c s dng nht.

Mt kiu reader c nh c tn gi l my in RFID, c th in ra mt m vch v ng thi to ra mt th RFID trn mt nhn thng minh. Mt nhn thng minh bao gm mt nhn m vch v c mt th RFID c nhng trong n. Cc kiu thng tin khc nhau, chng hn nh ngi gi v a ch ngi nhn, thng tin sn phm, cng c th c in trn nhn . Sau , my in RFID s c cc th nhn thng minh m n va mi ghi ln xc thc thng tin. Nu nh thng tin ny c li, th tc l my in a t chi nhn thng minh v n ch thc hin vic duy nht l in ra.Mt nghip v no m hin ang s dng m vch cho cc thao tc ca n th ta c th s dng RFID printer nh l bc u tin tip cn lm quen vi cng ngh RFID. Di y l mt vi hnh nh trong thc t v cc nhn thng minh v my in RFID:

My in RFID ca hng Zebra Technologies1.4.2.9.4. Thit b c th cm tayMt reader cm tay l mt reader di ng m ngi s dng c th thao tc n nh mt vt cm tay. Mt reader cm tay ni chung c xy dng a bao gm c anten bn trong n. Mc d cc reader ny c gi c rt t (v t c thng mi ha), tuy nhin, gn y vi nhng tin b trong cng ngh ch to reader th gi c ca cc thit b loi ny ang c xu hng gim dn. Di y l hnh thit b reader cm tay trong thc t.

1.4.3. Giao tip gia thit b c th v th

Ty thuc vo kiu s dng giao tip, giao tip truyn thng tin gia mt reader v mt th c th l mt trong cc cch s dng di y:- Kiu iu ch backscatter

- Kiu transmitter

- Kiu transponder

Trc khi i vo tng kiu giao tip truyn thng , ta s tm hiu qua v hai khi nim l trng gn v trng xa .

Khu vc nm gia mt anten ca reader v mt bc sng y ca sng RF c pht ra t anten c gi l trng gn. Cn khu vc nm pha ngoi bc sng y th c gi l trng xa. Cc h thng RFID th ng hot ng ti cc tn s LF v HF th s dng lin lc trng gn,cn ti cc tn s UHF th s dng lin lc trng xa. Cng ca tn hiu trong lin lc trng gn b gim i mt lng bng ly tha bc ba ca khong cch ti anten ca reader. Cn trong trng xa, n gim i mt lng bng bnh phng ca khong cch ti anten ca reader.T dn n mt h qu l,lin lc trng xa s ph hp hn vi phm vi c ln hn so vi lin lc trng gn.Di y l cc hnh nh minh ha trng gn v trng xa:

Tip theo ta s i so snh s ging nhau cng nh khc nhau gia hai thao tc c th v ghi th vi cc th c kh nng ghi c nn n, v d th EM4150 ca hng EM microelectronic.

Thao tc ghi th s mt nhiu thi gian hn thao tc c th di cng mt iu kin bi v mt thao tc ghi bao gm nhiu bc, c th l bao gm, bc kim tra khi to, bc xa i bt c d liu g ang tn ti trn th,bc ghi d liu mi ln th , v bc kim tra cui cng. Ngoi ra, d liu c ghi ln th thnh cc khi theo nhiu bc.V kt qu l,vi thao tc ghi ln mt th c lp c th mt ti hng trm mili giy hon thnh v thi gian s tng ln khi kch thc d liu tng ln. Tri ngc li vi iu , th nhiu th c th c c trong cng khong thi gian bi cng mt reader. Bi vy, thao tc ghi th l mt qu trnh nhy cm v cn phi xc nh th ch, c th l th m ta s thc hin

thao tc ghi ln. Nn,trong sut thao tc ghi th,bt c th no khc khng phi l th ch th ta khng nn trong phm vi ghi ca reader.

1.4.3.1. Kiu iu ch backscattle

Phng php truyn thng tin theo kiu iu ch backscatter c trin khai vi c cc th th ng cng nh l vi cc th bn tch cc. Trong kiu truyn thng tin ny, reader gi i mt tn hiu sng lin tc (CW) RF c bao gm thm tn hiu nng lng in xoay chiu v tn hiu xung ti th ti tn s ca sng mang (l tn s m ti reader hot ng). Thng qua u ni vt l , anten ca th s cung cp nng lng ti vi chip trn th. Thng thng phc v cho mc ch c th,thnh phn vi chip phi c a ln ti mc in p 1.2 vn .Cn thc hin ghi, vi chip thng phi a ln khong 2.2 vn t tn hiu ca reader. Sau vi chip thc hin iu ch hoc phn chia tn hiu u vo thnh mt dy cc mu on v off biu th d liu ca n v thc hin truyn d liu tr li. Khi reader nhn c tn hiu a c iu ch ny, n thc hin gii m mu v nhn c d liu trn th.Do , trong phng php truyn thng tin theo kiu iu ch backscatter, reader lun lun phi thc hin "bt chuyn" trc ,tip sau mi ti phin th.

Th s dng kiu truyn thng ny s khng th lin lc c ti cc thi im vng mt reader bi v n ph thuc vo lng nng lng c trn reader truyn d liu ca bn thn n. Hnh di minh ha kiu truyn thng backscatter.

1.4.3.2. Kiu transmitter

Kiu truyn thng tin ny ch c trin khai vi cc th tch cc. Trong kiu truyn thng ny, th pht i cc thng ip ca n ti mi trng xung quanh theo cc khong cch chun, bt chp c s hin din hay vng mt reader. Do ,trong kiu truyn thng tin ny, th lun lun phi thc hin "bt chuyn" trc reader. Hnh di minh ha phng php truyn thng tin theo kiu transmitter.

1.4.3.3. Kiu transponder

Kiu truyn thng tin ny c trin khai vi kiu th c bit c tn gi l transponder. Trong kiu truyn thng tin ny, th thng trng thi "ng" khi khng c truy vn t bt c reader no. Trong trng thi ny, th phi gi i theo chu k mt thng ip kim tra xem c reader no ang lng nghe n khng. Khi mt reader nhn c chng hn mt thng ip truy vn, n c th "nh thc " th n kt thc trng thi ng. Khi th nhn c lnh ny t reader, n thot khi trng thi hin ti v bt u hot ng tr li nh mt th transmitter trn. D liu trn th ch c gi i khi c mt reader c th truy vn n. Hnh di ch ra kiu truyn thng tin transponder.

1.4.4. Anten ca thit b c th

Thit b c th (reader) lin lc vi th thng qua anten ca n, l mt thit b ring bit c gn kt vt l vi n, ti mt trong cc cng anten. Nh a ni phn trc,mt reader c lp c th h tr ln ti bn cng anten.Khi pht tn hiu trn reader s iu khin anten pht i tn hiu RF ra bn ngoi xung quanh n v nhn v thng tin phn hi t th.Do anten c mt v tr quan trng tng ng vi reader trong h thng RFID. Thng thng trong thc t anten thng c ch to theo cch qun dy theo dng hnh vung, hoc cng c th ch to theo kiu cc ng mch PCB. Di y l mt s hnh nh trong thc t v antenca reader ca cc hng ch to ni ting.

By gi chng ta s tm hiu qua mt vi khi nim rt quan trng ca anten, l vng ph sng ca anten,s phn cc ca anten v nng lng ca anten. Ch rng , y ni cp n cc vn chung v anten ,tc l n c th lin quan n c anten ca th v anten ca reader.

1.4.4.1. Vng ph sng ca anten

Vng ph sng ca anten reader chnh l vng c (cng c gi vi ci tn khc l ,ca s c) ca reader . Ni chung, vng ph sng ca mt anten l mt min ba chiu c hnh dng phn no ging vi mt hnh elip trn xoay. Trong min ny, nng lng ca anten l hiu dng nht; do , mt reader c th c c mt th t pha trong min ny m t gp kh khn nht.

M hnh anten mu

Mt v d anten c cha cc bin dng li

1.4.4.2. S phn cc ca anten

Khng ging nh cc sng nc, cc sng in t khng b nh hng bi lc hp dn , v in trng ti cc im c th trong bt c hng no trn mt phng vung gc vi hng truyn. Nn thng thng cc anten nh hng phn cc thng theo chiu dc hoc theo chiu ngang

Phn cc tuyn tnh

Hng phn cc ca n cng c kh nng ph thuc vo thi gian. V d, trng in t c th xoay xung quanh mt trc m n lan truyn l mt hm ph thuc vo thi gian, nu nh khng c s thay i v bin ca n, th s to ra mt bc x phn cc trn.

Phn cc trn Bc x phn cc trn c th c coi nh l tng hp ca cc sng phn cc dc v phn cc ngang c s sai khc 90 v pha. Bng cch iu chnh t l ca cc thnh phn ngang v dc, v mi quan h v pha gia chng, chng ta c th to ra cc sng phn cc elip c nh hng ty .

Tm quan trng ca phn cc trong RFID: nhiu anten ca cc th RFID bao gm ch yu l cc ng dy kim loi i theo cng mt hng. Nu nh in trng c nh hng dc theo dy, th n c th hot ng y cc electron quay tr li v tin v pha trc t mt u ca dy dn ti mt dy khc, to ra mt in p nui chip trn th hot ng. Nu nh in trng c nh hng vung gc vi trc ca dy, th n ch n thun dich chuyn cc electron quay li v tin ln trc dc theo ng knh ca dy, th s khng to ra in p nui chip ca th.

Sng phn cc tuyn tnh tng tc vi anten tuyn tnh Khi mt sng phn cc trn i ti mt anten tuyn tnh, th ch c cc thnh phn dc theo trc ca anten l c hiu ng no xy ra. Do , mt sng phn cc trn s tng tc vi mt anten tuyn tnh ti bt c gc nghing no trong mt phng vung gc vi trc lan truyn, nhng trong mi trng hp th ch c mt na nng lng truyn i l c nhn.

Nn cch tip cn tt nht ch to cc th phn cc c lp l kt hp hai anten lng cc ln trn mt th c nh hng trc giao vi mt ci khc; cc th c bit n nh l cc thit k lng cc i (ci ny a ni qua phn anten ca th).

Vi cc anten ca reader chng ta cn ch rng, kh nng c th, khong cch c th l ph thuc rt nhiu vo s phn cc ca anten reader v gc to vi th.Vi cc loi reader hot ng ti cc tn s UHF th cc anten ca n c ch to da trn c hai kiu phn cc : phn cc thng v phn cc trn.1.4.4.3. Nng lng ca anten

n v o lng nng lng pht x ca anten c tn gi l ERP i vi cc nc chu u v l EIRP i vi Hoa K. ERP v EIRP khng ging nhau nhng c lin h vi nhau bi h thc EIRP = 1.64 ERP. Gi tr ln nht c th ca nng lng anten c iu chnh gii hn bi cc quc gia v quc t (v d, l FCC vi Hoa K).

1.4.5. My ch v h thng phn mn

My ch v h thng phn mm l mt cch ni gn nhm ch cc thnh phn phn cng v phn mm tn ti ring bit vi phn cng RFID ( l, reader, th, v anten). N bao gm nhiu thnh phn, nhng mc n ny ta ch quan tm n thnh phn middleware .

c th thu c li ch y t RFID, th nhng ngi thc hin cc gii php RFID phi tm cch kt hp d liu RFID vo bn trong cc quy trnh ra quyt nh ca h. H thng cc doanh nghip cng ngh thng tin l trung tm ca cc quy trnh . Do , tr khi cc h thng RFID c kt hp vo bn trong cc h thng thng tin doanh nghip v cc t chc u t vo RFID th mi c th ci thin c tnh hnh kinh doanh v hiu qu t chc. V chnh l ni, middleware hng n. Middleware l mt phn mm chu trch nhim kt ni phn cng RFID mi vi mt h thng thng tin doanh nghip hin c. Middleware chnh l cc cng c phn mm gip ngi s dng lm vic trn cc phn cng RFID.V vy nu thiu Middleware th phn cng RFID s khng b nh hng g c nhng n s tr nn v gi tr.

Middleware cn c s dng nh tuyn d liu gia cc mng RFID v cc h thng thng tin bn trong mt t chc. N thc hin sp nhp cc h thng RFID mi vi cc h thng thng tin hin c. N cng chu trch nhim v cht lng v kh nng s dng thng tin c to ra t cc h thng RFID. Mt vi middleware cn c chc nng ging nh mt cnh st giao thng , qun l cc lung d liu gia nhiu reader v cc ng dng, chng hn nh qun l dy chuyn cung ng v k hoch v cc ti nguyn ca ng dng, trong mt t chc.

Thut ng middleware a c p dng rt rng ri, khng ch trong RFID m trong c nghnh cng ngh thng tin, chnh v vy m n a bt u mt i ngha thc ca n. Khng ging vi cc cch dng middleware khc, RFID middleware thng thng c thit k hot ng ti vng bin ca mt mng thng tin hn l gn vng trung tm. V d, thnh phn middleware ca mt mng RFID thng c ci t s dng ti cc nh my hoc cc kho hng, khng phi ti trung tm ca t chc h thng thng tin . iu ny oi hi phi s dng ti mng li phn phi v s phn cp c s h tng thng tin.

RFID middleware thc hin nhim v dch chuyn d liu ti v t cc im giao dch. V d, trong mt quy trnh c th, middleware s dch chuyn d liu c cha bn trong mt th t reader ti h thng thng tin doanh nghip thch hp. Ngc li, trong mt quy trnh ghi ln th, middleware s di chuyn d liu t h thng thng tin doanh nghip ti reader thch hp v cui cng ti cc th thch hp.

Tm li ,RFID middleware c bn chc nng chnh l :

- Tp hp d liu - Middleware s chu trch nhim khai thc, tp hp v lc d liu t nhiu RFID reader thng qua mt mng RFID. N phc v nh mt vng m gia d liu c thu thp bi cc reader RFID v khi lng d liu cn thit c yu cu bi cc h thng thng tin doanh nghip trong mt quy trnh to quyt nh. Nu nh khng s dng ti b m ny th cc h thng thng tin doanh nghip s b qu ti bi cc lung d liu, v c th dn n mt cc d liu quan trng c tnh nhy cm.

- nh tuyn d liu - Middleware to iu kin thun li kt hp cc mng RFID vi cc h thng nghip v doanh nghip. N thc hin vic bng cch nh hng d liu ti h thng nghip v doanh nghip thch hp bn trong mt t chc. V d, mt s d liu c tp hp bi mng reader phi c a n lm u vo cho h thng qun l kho hng theo di hng tn kho, trong khi cc d liu khc phi c a n cc ng dng khc nh ng dng t hng hoc ng dng ghi n.

- Qun l cc quy trnh - Middleware c th c s dng kch hot cc s kin da trn c s cc quy tc nghip v. V d, mt n t hng c to ra trn trang web ca mt cng ty cn kho hng th c t xa , bao gm cc khay hng c dn cc th RFID. Sau khi n hng a c thit lp trn trang web, th h thng thng tin doanh nghip s chu trch nhim khi to thng tin vn chuyn v sau cc thng tin ny c chuyn n middleware, Ri middleware c nhim v xc nh v tr khay hng cn thit v ghi thng tin vn chuyn ln th dn trn khay hng . Cc s kin v cc qu trnh khc m middleware c th chu trch nhim qun l nh kim k, giy php vn chuyn, phiu vo ,phiu ra....

- Qun l thit b - Middleware cng c th c s dng gim st v iu phi cc reader. Vi mt t chc ln th phi c n hng trm , hng nghn cc thit b reader trn mng ca n. Nn kt ni mng v theo di tnh trng hot ng cng nh trng thi ca cc reader ny l mt cng vic ht sc quan trng v c th thc hin hiu qu nht iu l mc middleware.Ngoi ra thng qua middleware ta cng c th qun l t xa mt mng RFID. Nhiu sn phm middleware hin ti l c pht trin da trn c s tiu chun EPCglobal, hoc bit n vi ci tn l Savant. Cc c im k thut Savant phn loi cc thnh phn middleware da theo cc chc nng m chng phc v nh hnh bn di. (cc tiu chun EPCglobal c ni n k hn phn cc tiu chun).

1.4.6. C s h tng truyn thng

Thnh phn ny cung cp kh nng kt ni,kh nng bo mt v cc chc nng qun l h thng cho cc thnh phn khc nhau ca mt h thng RFID, v do n l phn khng th thiu ca h thng. N bao gm dy v mng khng dy, v cc kt ni ni tip gia cc reader, b iu khin, v my vi tnh. Kiu mng khng dy y c th l mng PAN, mng LAN hoc mng WAN .

1.4.7. Cc thnh phn ph khc

Cc thnh phn ph khc ni n y , bao gm cc cm bin, thnh phn bo hiu ,b truyn ng.

Mt reader khng th cho hot ng ti tt c cc thi im; ngoi ra n c th c khi ng (hoc l dng li) mt cch t dng nu cn . C uwocj nh vy l do c mt cm bin c gn vo reader .Cm bin ny c th c s dng bt hoc tt reader da trn c s mt vi s kin bn ngoi c pht hin bi cm bin ny. Do cm bin c dng to ra mt vi kch hot u vo tt hn cho reader.

Thnh phn bo hiu c th l mt tn hiu in t hoc l cc ch th. C th thy cc v d v b bo hiu nh cc cnh bo m thanh, cc b sng,... Mt b sng (light stack) bao gm cc ch th c cc mu khc nhau c xp xp theo th t thng ng v n rt c ch trong vic hin th cc trng thi khc nhau ca cc thuc tnh khc nhau trong h thng. V d, ch th c ngha l khng c c th hoc d liu trn th c li, ch th xanh c ngha l khng c th c.

B truyn ng l mt thit b c kh c dng iu khin v di chuyn cc i tng. Cc v d ca b truyn ng nh PLC (programmable logic controller), robot arm, kt cu c hc arm cho mt ca truy nhp,... Trong PLC l mt trong nhng b truyn ng linh hot nht, v PLC c s dng rng ri trong cc k hoch ch to.

Do c b truyn ng v b bo hiu u c th c s dng cung cp cc u ra cc b kh tt cho h thng RFID,chng hn nh cc cnh bo audiovisual trong trng hp xut hin li khi c,hoc m mt ca truy nhp khi c thnh cng.

LED nhiu tng1.5. Cc tiu chun cng ngh RFID

Nhiu tiu chun cng ngh RFID a c xut t nhiu t chc khc nhau trn th gii. m t y v cc tiu chun , c l phi cn n c mt cun sch v n. Nn y ta ch cp s qua v mt s tiu chun ang s dng ngy nay v c a s cc cng ty sn xut cc thit b RFID tun th theo. Di y l tn cc tiu chun chnh cng tn cc cc t chc nh ngha n i km theo:

- ANSI (American National Standards Institute)

- AIAG (Automotive Industry Action Group)

- EAN.UCC (European Article Numbering Association International, UniformCode Council)

- EPCglobal

- ISO (International Organization for Standardization)

- ETSI (European Telecommunications Standards Institute)

- ERO (European Radiocommunications Office)

- UPU (Universal Postal Union)

- ASTM (American Society for Testing and Materials)

- CEN (Comit Europen Normalisation (European Comite for

Standardization )

By gi ta s tm hiu s qua v hai tiu chun ANSI v EPCglobal c ci nhn tng quan v chng.

1.5.1. Tiu chun ANSI

ANSI l mt t chc t nhn phi li nhun, thng ch ng ra cc tiu chun v cc h thng nh gi chun ca Hoa K. Nhim v ca vin l nng cao kh nng cnh tranh ton cu ca Hoa K trong kinh doanh cng nh cht lng cuc sng ngi dn Hoa K bng cch thc y v to s ng thun tnh nguyn v cc tiu chun, cc h thng nh gi, v bo v tnh ton vn ca chng.

Mt vi tiu chun chnh ca ANSI v cng ngh RFID m n a c s dng trong cc ng dng thc t c cp di y:

- ANS INCITS 371. Thng tin v v tr ca cc h thng thi gian thc. Ci ny bao gm ba phn nh di y:

Phn 1. Cc giao thc giao tip trn khng ti di tn 2.4 GHz.

Phn 2. Cc giao thc giao tip trn khng ti di tn 433 MHz.

Phn 3. Giao tip vi cc chng trnh ng dng.

- ANS MH10.8.4. Tiu chun ANSI cho cc ng dng RFID vi cc container bng nha c th s dng li c.

1.5.2. Tiu chun EPCglobal

EPCglobal, Inc, l mt lin doanh gia cc t chc quc t UCC v EAN. Mc ch ca EPCglobal l thit lp cc tiu chun trn ton th gii v thit k v trin khai thc hin thng qua EPC (Electronic Product Code) v EPCglobal Network . Cc c im k thut EPCglobal nhm n mc tiu l hot ng ca cc chui cung ng v c xem l cc c im k thut ha hn nht cho cng ngh RFID trn ton cu ,ngoi ra n cng c th p dng c cho mng rt rng cc ng dng khc na.

Di y ta s tm hiu qua v EPCglobal Network, ci c xem l thnh phn nn tng ca EPCglobal.

EPCglobal Network l mt tp hp cc cng ngh, c th cung cp t ng, nhn dng thi gian thc v chia s d liu thng minh ca mt danh mc mt hang c bn trong v bn ngoi mt doanh nghip. Tt c cc ci ny rt ph hp vi cc hot ng ca mt chui cung ng trong mt doanh nghip, tuy nhin n cng c th trin khai c vi cc kiu ng dng khc na.

Nm thnh phn cng ngh chnh to nn cc tiu chun EPCglobal Network, bao gm:

- Electronic Product Code (EPC).

- Data-collection hardware bao gm cc loi th v reader EPC. Ci ny cng c bit ti nh l h thng ID.

- EPCglobal middleware.

- Discovery Services (DS), V d, ONS (Object Naming Service) l thuc thnh phn ny.

- EPC Information Services (EPCIS).

EPC (Electronic Product Code) l mt tm nhn dng a c cp php, m c th nhn din c bt k danh mc mt hng no trong mt chui cung ng. N rt n gin v nh gn v c th to ra s lng rt ln cc nh danh duy nht. ng thi, n cho php a vo cc m k tha v cc tiu chun cho ph hp vi tng hon cnh c th chng hn nh:

- Global Trade Identity Number (GTIN). Ci ny cung cp mt s EAN-UCC duy nht trn ton cu phc v cho vic nhn dng cc sn phm v cc dch v.

- Unique Identification (UID). Ci ny c s dng nh s theo di ti sn ca B Quc Phng M.

- Global Location Number (GLN). Ci ny c s dng biu th cc v tr, cc i tc thng mi, v cc thc th php l.

- Serial Shipping Container Code (SSCC). Ci ny c s dng nhn dng n v vn chuyn chng hn nh mt khay hng, mt thng cc tng.

Ngy nay mt cng ty ang s dng m vch trong cc hot ng ca h c th c mt cch d dng chuyn sang s dng cng ngh RFID bng cch dng EPC. Mt m EPC c th c s dng xc nh cc thuc tnh khc nhau ca mt danh mc mt hng, chng hn nh:

- Phin bn EPC c s dng.

- Thng tin nhn dng nh sn xut.

- Kiu sn phm.

- Chui s duy nht ca danh mc mt hng.

1.5.3. Tiu chun ISO

ISO l mt mng li cc vin tiu chun quc gia ca 146 quc gia, trn c s mi nc l mt thnh vin, vi trung tm t ti Geneva, Thy S. ISO l mt t chc phi chnh ph.

ISO c cc y ban k thut (Technical Committee-TC) v cc hi ng k thut chung (Joint Technical Councils -JTC) c tham gia xy dng cc tiu chun c lin quan n RFID bao gm:

- ISO JTC1 SC31

- ISO JTC1 SC17

- ISO TC 104 / SC 4

- ISO TC 23 / SC 19

- ISO TC 204

Di y l mt s tiu chun ISO c lin quan n cng ngh RFID m n a c s dng trong cc ng dng thc t:

- ISO 6346. Nhn dng v nh du m cc vn chuyn container.

- ISO 11784. Tn s v tuyn xc nh cu trc m s nhn dng ng vt s dng RFID. Tuy nhin, n khng ch ra bt c c tnh no ca giao thc truyn gia mt th RFID v mt reader.

1.6. Quyn ring t v tnh bo mt trong cng ngh RFID

By gi, chng ta bt u tm hiu v vn ring t v tnh bo mt trong vic s dng cc h thng RFID v mi quan tm ca ngi tiu dng v cng ngh ny. Chng ta s cng i lt qua cc kha cnh chnh ca hai vn trong h thng RFID, ln lt t tng vt l ti tng ng dng.

1.6.1. Quyn ring tVic kim tra trong thc t cc mi e da n s ring t v an ton ca ngi dng t vic s dng cc cng ngh RFID l rt quan trng. Mi cng ngh u mang trong n mt kh nng no , nhng khng c m bo 100%, cng nh khng c lm dng n. V d vi vic cp php gn th RFID ln cc loi thuc. Th vi cc loi thuc iu tr cho cc bnh nhn trm cm hay cc bnh nhn AID c th s khin mi ngi rt lo ngi rng mt ai c th tm ra h a s dng chng n gin ch bng cch c th RFID t mt khong cch no . Tuy nhin, s dng cch ny c th gip loi b tnh trng gi mo thuc ht hn hoc bn thuc ra ngoi, hoc c th s dng ti thi im bn thng bo cho c dc s v ngi tiu dng v vic a xy ra tiu cc trong giao dch. V vy cho ta thy mt iu rng, cc mi quan tm v tnh ring t nn c cn bng vi cc li ch ca ngi tiu dng.

1.6.1.1. Cc bin php bo v quyn ring t da trn c s php lut

Nhiu chnh ph hin ang tranh lun v lut php bo v ngi tiu dng v vic s dng d liu RFID trong c hai lnh vc cng cng v c nhn.Tuy nhin cho d cc b lut c bit s c a vo thc y s tnh ring t v bo mt ca RFID i na th cc vn y vn cha c r rng. M quan trng nht l cc chnh ph phi cn bng c nhu cu v tnh ring t ca ngi tiu dng cng nh ca mt ngi dn vi nhu cu ca cng ty trong vic thu thp d liu tip th v nhng li ch x hi ni chung nh hiu qu ca vic a vo dy chuyn cung ng s dng cng ngh RFID. Mt vi d n lut c lin quan n bo v tnh ring t ca d liu, a c gii thiu trong sut phin iu trn th 108 ca quc hi Hoa K. i din tiu bng Wisconsin Gerald D. Kleczka a xut mt d lut yu cu phi c cc nhn cnh bo trn cc sn phm gia dng c cha thit b RFID. l d lut, H.R.4673, a c gii thiu di tiu l "Opt Out of ID Chips Act". Trong thng tm nm 2004, Thng vin tiu bang California a thng qua mt bin php thit lp gii hn s dng cng ngh RFID ca cc th vin, nh bn l v cc t chc t nhn khc. c bit n vi ci tn l SB1834, d tho lut ngn cm cc doanh nghip v cc th vin California s dng cc th RFID gn ln sn phm tiu dng hoc s dng mt u c RFID nhn dng mt c nhn,tr trng hp trong mt s hon cnh no .

1.6.1.2. Cc bin php bo v quyn ring t thng qua vic ci tin cng ngh Cc c ch v cng c hn ch cc kh nng gim st khng an ton hoc tri php ca cc h thng RFID c th nng cao hiu qu ca cc b lut v cc nguyn tc v quyn ring t. Mt s cng ngh c xut nh cc tiu chun kill tag ca EPCglobal v blocker tag ca RSA Security. Cch tip cn vi khi nim kill tag l cch n gin nht tin ti thc y s ring t ca ngi tiu dng. Trong cch tip cn ny, ngi tiu dng c th lin h trc tip vi mt nh bn l no ra lnh hy th RFID c nhng vo bn trong sn phm sau khi a mua n. Vi phng php ny c th bo v cc ti sn ca h khng b qut bi cc tn s v tuyn tri php.

Hn ch chnh ca phng php kill tag l , n gii hn cc c tnh hu dng ca cng ngh RFID ti cc im bn hng. Nu nh sn phm cn phi c tr li cho ca hng sau v mt l do no , th vic nhn dng th RFID trn sn phm vn rt cn thit, v nh vy ta phi thc hin li cng on to th. Ngoi ra vi vic thc hin phng php kill tag ngi tiu dng s mt nhiu thi gian hn cho vic mua sm cng nh s phi xp hng di ch i hy th RFID.

Cn cch tip cn blocker tag, c xut bi t chc RSA Security, s dng mt th c dng gi l th chn c thit k gy nhiu th ng cc reader, khin chng khng c c t cc th RFID bnh thng khc. Cc th chn lm vic theo cch lm nhiu cc thut ton chng xung t ca mt reader trong mt phm vi c ca cc th ID.

1.6.2. Tnh bo mt

Nh vi bt c h thng no, xc nh chin lc bo mt vi cc h thng RFID, chng ta bt u bng vic kho st tt c truy nhp nh th chng ang n t cc tc nhn e da tim tng.

1.6.2.1. Vng mt : cc th RFID

Vng mt bao gm bn thn cc th RF

C hai khu cc chnh d b tn thng l:

- D liu lu tr trn th m khng c m ha.V thm vo cc iu kin bo mt ln th th cn thit phi tng thm khng gian v cc khi mch trn cc chip RF. iu ny c ngha l gi thnh ca th s tng ln ,thi gian x l cng tng ln.

- Khng c mt c ch gim st vt l, nn bt c ai trn c s c quyn truy cp n cc th th cng c th loi b mt th hoc chuyn i cc th cho nhau.

Nhn t e da: Cc nhn t e da c th l bao gm bt c ci g m c th truy nhp vt l ti th v c th lm thay i ni dung ca n.

V gii quyt cc vn , ta c mt vi bin php i ph di y:

- Thc hin gim st cc hng ha c gn th RFID.

- Yu cu kim sot nghim ngt cc truy nhp ti thng tin c th ly c t mt m EPC.

- Tch bit m EPC t bt c thng tin no m nhy cm vi cc doanh nghip v ngi tiu dng.

- Ch s dng cc th c kh nng ghi li c ti nhng ni thch hp c kim sot truy nhp hp l.

1.6.2.2. Vng hai: cc thit b c th RFID

Cc reader RFID thng c kt ni ti mt mng ni b bng cch s dng cc kt ni c dy hoc l cc kt ni khng dy.

Cc l hng bo mt c th xut hin nh:

- D liu c truyn t th ti reader cha c m ha.

- Cc reader khng c c ch xc nhn cc th.

chnh l cc nguyn nhn dn n s gi mo , hoc cc cuc tn cng DoS, hay tn cng giao thc.

Cc nhn t e da: Cc nhn t e da bao gm bt c ci g c kt ni n cng mng (ging nh bt c nt mng no c kt ni n mt mng, mt reader s c m ti tt c cc nhn t trn mng), v bt c ai vi mt thit b khng dy cng mt cht kin thc v cc giao thc ca reader m c xu.

1.6.2.3. Vng ba: tuyn dch v RFID

Tuyn dch v RFID l mt nhm cc thnh phn middleware bao gm dch v ONS (Object Naming Service), qun l s kin EPC, my ch EPCIS, v my ch tch hp RFID.

Cc l hng bo mt: Cc thnh phn ca tuyn dch v RFID lin lc vi cc h thng thng tin ni b ca cc doanh nghip(trn cc mng LAN v WAN) v vi i tc v cc h thng cng nghip (trn mng Internet).

Cc nhn t e da: Cc nhn t e da bao gm cc ip vin ca cc cng ty, cc i l gin ip, v cc k xm nhp bt hp php.

1.6.2.4. Vng bn: cc h thng thng tin doanh nghip Cc h thng thng tin doanh nghip bao gm cc h thng ca cng ty chng hn nh, h thng qun l nhn dng, h thng iu khin truy nhp, cc h thng gi thng bo, v tt c cc h thng ph tr m s tr thnh khch hng ca d liu RFID. Cc h thng ph tr y l bao gm cc h thng ERP. Cc l hng bo mt : Cc giao dch v khi lng d liu cn thit ca cc h thng RFID c th p o cc c s h tng mng hin c. Cc cng ty c th phii mt vi cc tnh hung cn lu tr bt ng hoc cc thng tin nhy cm.

Cc tc nhn e da : Cc tc nhn e da bao gm cc gin ip ca cc cng ty, v nhng k xm nhp tri php.

1.7. So snh gia cng ngh RFDI v cng ngh m vch

Mt m vch l mt lot cc sc en , trng ni tip nhau vi cc chiu rng gia chng khc nhau, sao cho to thnh mt nh dng m my mc c th hiu c. M vch l mt cng ngh quang in t, trong nh sng laser s phn x tr li cc biu tng m vch v sau cc biu tng ny s c c bi mt my qut.

Cc biu tng m sn phm ph bin khp ni (UPC) l hnh thc ca m vch m a thn thin vi nhiu ngi. Nghin cu v m vch a bt u trc t rt lu trc khi ni nn cc tiu chun UPC.Tuy nhin, mi ti nm 1952, hai nh nghin cu ti IBM a c trao bng sng ch u tin cho cng ngh nhn dng t ng .Mi ti nhng nm su mi , mi xut hin h thng thng mi ha u tin ,nhng ch yu s dng cc ga ng st vn chuyn hng ha v sn phm. Sau ,trong nhng nm u tin ca thp k by mi, mt tp on tp ha ca Hoa K a triu tp mt y ban c bit nh gi cng ngh m vch, vi mc ch l trin khai n trong cc chui siu th trn khp c nc nh l

mt phng tin gim chi ph lao ng, ci thin tc tnh tin v theo di hng tn kho. Vo nm 1973 ,cc tiu chun UPC ra i t cc n lc trn v tr thnh nh hng chnh trong vic trin khai cng ngh m vch.

Tng trng ca cc ca hng tp ha a gim trong sut nhng nm by mi. y khng phi do li ca cc ca hng tp ha, m phn ln l do cc cng ty cung cp a sn xut ra cc sn xut ra cc sn phm vi tc rt chm do cn phi bao gm thm cc biu tng m vch trn bao b ng gi. V trong nm 1978, th cch nh m a c ci thin mnh m v cc h thng qut m vch cng bt u xut hin ph bin. Sau , vo nm 1981, DoD khi to chng trnh LOGMARS , trong yu cu tt c cc sn phm bn cho qun i phi c nh du 39 biu tng m m sau ny a tr thnh mt tiu chun m khc song hnh cng tiu chun UPC.

M vch tiu chun UPC

M vch tiu chun code39Thit b c m vch cng c gi l my qut s s dng mt chum nh sang qut ngang qua m vch. Ni chung hng qut khng lin quan nhiu n kt qu cui cng. Tuy nhin, trong sut qu trnh qut, chum sang khng c di chuyn ra ngoi khu vc m vch. Do , ni chung, khi tng chiu di m vch th cng c ngha l tng chiu cao ca my qut ph hp vi lch ln hn ca chm sng bn ngoi khu vc m vch trong sut qu trnh qut. Trong sut qu trnh c, thit b c phi nh lng cng ca chum sang phn x tr li bi cc khu vc en v trng cho m vch . L do bi mt thanh ti s hp th nh sng, cn mt khong trng s phn x nh sang tr li. Mt thit b in t c gi l photodiode hoc photocell s chuyn i m hnh sang ny thnh mt dng in (hoc l tn hiu tng t). Cc mch in sau s gii m cc tn hiu in ny thnh cc tn hiu s. D liu ny l nhng g m ban u c m ha bi m vch. Cc d liu s thu c c biu din di dng cc k t ASCII.

Trong m vch, chm nh sang laser c s dng nh l cc sng mang d liu. Ngc li, cc th RFID ni chung thng s dng cc sng v tuyn mang thng tin. Do m vch c cp ti nh mt cng ngh quang in t cn RFID th c gi l cng ngh RF. Di y l cc so snh chi tit gia mt th RFID v mt m vch.

Kch thc b nh, hay l khu vc lu tr d liu : Cc m vch ch c th cha mt lng ha hn d liu. Cc th nh nht, v lu tr d liu, l cc biu tng E ca chun UPC, m ch lu gi c tm k t; ch l mt vi byte. Ti ni i din vi v tr cui ca quang ph, ma trn d liu theo tiu chun m vch cho php lu tr ln ti 2000 k t ASCII, trn mt th hai chiu, nh ch ra hnh di y.Ch l thut ng th s dng y khc vi trong cng ngh RFID.

Cc th RFID c kh nng lu gi thng tin nhiu hn rt nhiu. Mc d cc th RFID c th c ch to vi cc b nh nh hn lu gi ch mt vi byte, nhng vi v tr hin ti ca cng ngh c th t gii hn ln ti 128 Kilo byte, ln hn rt nhiu so vi cc biu tng m vch.

Kh nng oc/ ghi : M vch khng th sa i c mt khi chng a c in ra, do m vch c bit ti l mt cng ngh RO. Ngc li, cc th RFIDRW , li c c kh nng c v ghi ti b nh, v s ln nh dng th trong sut qung i tn ti ca n c th ln ti hng nghn ln, y cng l mt phn a khin cho cng ngh RFID tr nn mnh m nh vy.

Khng cn ng ngm : Mt u th khc ca cng ngh RFID so vi cc m vch l cc h thng RFID khng cn n mt ng ngm gia mt th v thit b c c th lm vic ng. Bi v cc sng v tuyn c kh nng lan truyn qua nhiu cht liu rn khc nhau, tc l hiu qu c vi cc th RFID nm su bn trong mt khay hng khng km l bao so vi cc th nm trc tip trn ng ngm. Nhng vi m vch th khc, cc m vch phi nm trn ng ngm ca my qut th n mi hot ng ng c. iu ny c ngha l cc m vch phi c t bn ngoi bao b cng nh cc i tng c gn th khng c t su bn trong khay hng trong qu trnh c. Trong cc ng dng qun l chui cung ng, trong hu ht cc thi im u c mt s lng ln hng ha di chuyn, nn rt kh c c mt ng ngm ca my qut vi mt hng ha c th. y chnh l u im ln ca cng ngh RFID so vi cng ngh m vch.

Phm vi c : Phm vi c ca m vch c th c c mt khong kh di. Thng thng cc phm vi c c gi tr vo khong c vi chc cm. Tuy nhin cc phm vi c ca cc th RFID li c mt khong thay i kh rng, ph thuc vo tn s hot ng ca h thng, kch thc anten v th ang s dng l th tch cc hay th th ng. Thng thng, cc phm vi c ca cc th RFID c th chy t vi cm ti vi mt.

Tnh bo mt truy nhp : D liu m vch c tnh bo mt rt thp. Bi v cc m vch cn thit phi c mt ng ngm nn phi c t r rng bn ngoi bao b, do bt c ai vi mt my qut m vch chun hoc ch vi mt chic camera cng c th xem trm hoc ghi li d liu trn . Nhng vi cc h thng RFID th li c cung cp mt mc bo mt cao hn rt nhiu. Nh a cp cc phn trc, cc h thng RFID c kh nng ngn chn cc bn th ba, hn ch truy nhp tri php ti h thng, v bo v d liu nhy cm.

bn, tnh nhy cm vi mi trng : Cng ngh RFID c kh nng chu ng tt hn vi bi bn v mi trng khc nghit so vi cng ngh m vch. Cc m vch c th s khng c c nu nh chng b bao ph bi bi bn, hoc l b rch nt. Ngoi ra trong mt mi trng vi nh ng cng cao cng c th gy tr ngi cho my qut m vch m ti t hn l khng th c c cc m vch. Ring vi cng ngh RFID th cc vn ny khng nh hng g nhiu ti n.

Kh nng c n nh : Trong cc ng dng chui cung ng, c chnh xc ngay ln u sn phm i qua n l rt quan trng duy tr hiu qu hot ng cao. Vi cc m vch th thng phi c qua h thng ti hai ln hoc thc hin c bng tay. R rng nh vy rt bt tin v nh hng nhiu ti hot ng chung ca ton h thng. Vi cc h thng RFID, thng qua cc thut ton chng xung t v cc tnh nng RW , c th loi b c vic sn phm phi qut nhiu ln mi thu c thnh cng d liu.

Gi thnh : Ro cn ln nht ngn cn s tng trng ca cng ngh RFID chnh l chi ph cho cc th. Trong khi m vch thng c gi di 0.01 la th chi ph hin ti cho mt th th ng vi phm vi c vi cm l cao hn rt nhiu.

1.8. Kt lun

Nh vy chng ny ta a i tm hiu qua v cc kiu th RFID, cc loi reader cng nh hot ng ca mt h thng RFID trong thc t. Tuy ch tm hiu mc s si ,song y s l nhng kin thc c s cn thit chng ta c th i vo thit k mt thng qun l bnh nhn chng sau. Ngoi ra , chng ta cng a c thm nhng kin thc hiu bit v quyn ring t v tnh bo mt ca cng ngh RFID. N rt c ch vi mi ngi tiu dng chng ta trong vic s dng cc h thng RFID cng cng nh cc siu th chng hn .Cng nh rt c ch vi vi cc nh pht trin , gip h bit cch i ph vi cc l hng bo mt.CHNG 2: QUN L HC SINH BNG CCH S DNG RFIDTrong chng ny s ni r cch to c s d liu trong access va cch to chng trnh trong VB.net.

V n ny ch yu tp trung ti cch ng dng rfid trong cch qun l sinh vin nn s t cp n vic thit k mch rfid.V sau y l cc bc to nn mt h thng qun l sinh vin :I. ng dng ca Microsoft Access 2003 trong vic to ra c s d luTrong bi ny nhm s dng office 2003 nn bn no khng c th c th s dng cc loi office khc.1. To cc tableu tin cc bn s m access ra v to mt file mi vi tn la quan li sinh vien sau chon tablecreat table in designview. N s hin ra 1 khung nh hnh v ri in y thng tin theo yu cu.

V cc bn s to 4 bng nh vy vi cc tn nh sau :SINH VIEN, KHOA, MON HOC v KT QU .Cc vng c gch di l vng kha, trong bng SINH VIEN kha chnh MSSV, bng KHOA vng kha l makhoa,bng KET QUA c ba vng kha l Mamh, Lanthi, masv, bng MON HOC vng kha ca n l mamh

i vi SINHVIEN s to theo yu cu sau:

FieldData typeDescription

MSSVTextM s sinh vin

HolotTextH lt

TenTextTn

NamYes/noNam

NgaysinhDate/timeNgy sinh

Ni sinhTextNi sinh

DiachiTexta ch

TinhTextTnh

HocbongNumber(long interger)Hc bng

LylichMemoLy lich

KhoamakhTextM khoa

KHOAField nameData typeDescription

makhoaTextM khoa

TenkhoaTextTn khoa

KETQUAField name Data typeDescription

mamhTextM mn hc

lanthiNumberLn thi

masvTextM s sinh vin

DiemNumberim

MON HOCField nameData typeDescription

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