báo cáo hệ thống wifi

8/3/2019 Bo co h thng Wifi

1/16

I HC S PHM K THUT TP. H CH MINH

BI BO CO H THNG WIFI

Ging vin: Phm Xun H

SV thc hin: Ng Long Huy (MSSV: 10917013)

Nguyn Ngc Tun (MSSV:10917074)

Nguyn Thanh Danh (MSSV: 10917008)

TP HCM 04/2011

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2/16

MUC LUC

I. Tm hiu v Wifi3

1. Wifi l g?.............................................................................................3

2. Wifi hot ng nh th no?................................................................3

II. Cu to v qu trnh hot ng ca h thng Wifi4

1. Cu to h thng Wifi....4

2. Qu trnh hot ng ca h thng Wifi..4

III. Cc m hnh Wifi v ng dng ca Wifi...6

1. Cc m hnh Wifi..6

1.1 Chun wifi ph bin hin nay.6

1.2 M hnh thu pht wifi hin nay..7

1.3 Tnh cht hot ng7

2. ng dng ca Wifi...9

IV. S pht trin ca Wifi trong tng lai.13

V. Bo mt trong Wifi..14

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3/16

I. Tm hiu v Wifi.

1. Wifi l g?

Wi-Fi hay wifi hay mng 802.11 u l nh nhau. N c vit tt ca t

Wireless Fidelity (khng dy trung thc). Thc ra n c tn l The Standard for

Wireless Fidelity ( chun cho khng dy trung thc).

Wi-Fi l mt mng khng dy c kh nng kt ni vi mng khc hay vi

my tnh bng sng v tuyn. N nhanh hn v phm vi hot ng ln hn

Bluetooth. H thng ny hot ng mt s sn bay, qun caf, th vin

hoc khch sn. H thng cho php truy cp Internet ti nhng khu vc c sng

ca h thng ny, hon ton khng cn n cp ni. Ngoi cc im kt ni

cng cng (hotspots), WiFi c th c thit lp ngay ti nh ring.

Mt ngi vi thit b c ci t Wi-Fi nh my tnh, in thoi, PDA c th

kt ni Internet khi gn im truy cp.

Tn gi 802.11 bt ngun t vin IEEE (Institute of Electrical and

Electronics Engineers). Vin ny to ra nhiu chun cho nhiu giao thc k

thut khc nhau, v n s dng mt h thng s nhm phn loi chng; 3 chun

thng dng ca WiFi hin nay l 802.11a/b/g.

2. Wi-Fi hot ng nh th no?

Truyn thng qua mng khng dy l truyn thng v tuyn hai chiu.

C th:

- Thit b adapter khng dy (hay b chuyn tn hiu khng dy) ca

my tnh chuyn i d liu sang tn hiu v tuyn v pht nhng tn

hiu ny i bng mt ng-ten.

- Thit b router khng dy nhn nhng tn hiu ny v gii m chng.

N gi thng tin ti Internet thng qua kt ni hu tuyn Ethernet.

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4/16

Qui trnh ny vn hot ng vi chiu ngc li, router nhn thng tin

t Internet, chuyn chng thnh tn hiu v tuyn v gi n adapter

khng dy ca my tnh.

y l hnh minh ha:

II. Cu to v qu trnh hot ng ca h thng Wifi.

1. Cu to h thng Wifi.

Truy cp Internet khng dy gm 4 thnh phn: ng truyn tc

cao, mt cng mng, mt mng khng dy, v ngi dng khng dy.

2. Qu trnh hot ng ca h thng Wifi .

Ngi dng s kt ni vi mng khng dy qua cng mng, v sau n s

khi chy trnh duyt Internet

ng truyn tc cao: l mt s kt ni Internet bng thng

rng. Vic kt ni ny s nhanh hn so vi dch v kt ni quay s.

Cng mng: n hot ng ging nh l mt cng tht s. N c

nhim v l ngn chn nhng truy cp vo mng khng dy ca

bn m khng c php, ng thi n cng cung cp nhng cng

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5/16

c qun l rt tt nh thm quyn, kim tra mng, v cc dch khc

nh in n, voice thng qua IP.

Mng LAN khng dy l mt h thng kt ni my tnh ca bn

vi cc thit b khc bng sng v tuyn thay v l dy dn.

Ngi dng khng dy l nhng ngi m c mt my tnh vi

mt adapter khng dy, l nhng phng tin h truy cp khng

dy vo Internet. Adapter khng dy c th c tch hp sn,

hoc l mt thit b ri s dc cm vo my tnh

M hnh tiu biu cho mng Wifi

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6/16

Sng v tuyn c truyn t cc anten c cc router, v s c nhn

bi cc b nhn Wifi nh cc my tnh, in thoi di ng c trang b card Wifi.

Khi cc thit b ny nhn c tn hiu th cc card Wifi s c tn hiu v to kt

ni khng dy. Mt khi mt kt ni c thit lp gia ngi dng v mng th

ngi dng s c nhc nh bng mt mn hnh login v password nu nh l

mng thu.

Vng ph sng bi 1 hay nhiu AP c gi l hot spot. Mt hot spot c phm vi

khong t 1 cn phng n vi dm. Trn th gii th cc hot spot ny dc t

cc thnh ph mt ngi vi mt laptop c th truy cp internet, hot spot c

khp ni nh trong nh hng, khch sn, trng hc, sn bay

III. Cc m hnh Wifi v ng dng ca Wifi.

1.Cc m hnh Wifi.

1.1 Chun wifi ph bin hin nay:

- Chun 802.11b : 2.4 GHz , tc 11Mbps, bn knh

100m, b nhiu.

- Chun 802.11G : 2.4GHz, tc 54Mbps, bn knh

200m,t nhiu hn.

- Chun 802.11n: 2.4Ghz, tc 300Mbps, bn knh

600m, t nhiu nht.

Thit b pht sng Access Point(AP):

- Indoor: dng trong nh.

- Outdoor: lp t ngoi tri.

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7/16

M hnh n gin:

1.2 M hnh thu pht wifi hin nay:

- a s cc wifi hin nay s dng Anten Omni, a hng pht

ra 3600, ng hng gc pht tp trung mt hng nht nh.

-Mi AP u c gii hn truy cp di 25 Client.- Cht lng sng gim ng k khi gp nhiu v vt cn.

- AP gn nhau s gy nhiu ln nhau.

- Khng th xc nh hng truy cp ca Slient.

- Khng th hiu chnh hng pht sng.

- Khng th trin khai din rng, qun l kh khn.

- Gp vn bo mt, gii hn truy xut, t c nhng thit b htr.

1.3 Tnh cht hot ng:

Anten Omni (Wifi thng dng):

- Nng lng sng wifi cng ging nh s pht ra nh sng ca

bng n. Sau khi c cp ngun nh sang t bng n s

c pht ra xung quanh c nhng vng khng mong mun gyra hao phi nng lng.

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8/16

Beam Flex (Wifi thng minh):

- Gm:

Self leaning(T chnh hng), Self Opimizing(T ti u ha),

Self healing wifi angtenna system(T chnh sa h thng anten

ca wifi).

Cng ngh BeamFlexTM t ng iu hng tn hiu pht ca

anten.

iu chnh hng pht sng, la b tn hiu nhiu.

Kt hp cc vng sng m rng h thng.

Sp t / nh hng hon ton khc bit nhm tng

thch hon ton vi cc thit b thuc chun 802.11.

Khc vi Omni antennas. Tnh hiu pht t anten BeamFlex

ging nh nh sng n pin.

-Nu cp ngun cho n trn, n lp tc pht ra xung

quanh.-Nu bn cng cp 1 ngun nng lng nh vy cho n

pin, nh sng pht ra s c tp trung v r hn.

Omni anten truyn thng pht sng ging nh bng n

trn.

Beamflex antenna tp trung nng lng pht ra nh l

chm tia sng chiu n tn ni nhn.

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9/16

2. ng dng ca Wifi.

Kh nng truy cp mng internet khng dy khng ch l tin ch duy

nht ca wifi.Wifi cn c cc ng dng khc nh:

-Bin in thoi tr thnh iu khin t xa

Mng wifi c kh nng kt ni tt c cc thit b in t trong

cn h ca bn. V thng qua my in thoi cm tay, bn c th iu

khin mi vt dng.

Cc hng ch to in thoi ln rt quan tm ti tnh nng hu

ch ny. iTune controlling remove ca Apple, All Encompassing

Gmote trn nn Android v XBMC remotes l nhng ng dng ph

bin hin nay. Nu c mt chic in thoi thng minh, bn nm

gi c th gii s trong tay.

-iu khin my in t xa

iu khin my in lun l mt vn "au u" vi nhiu nhn

vin vn phng, khi hu ht cc cng ty khng th trang b my in cho

mi c nhn hoc phng ban.

Thay v phi tho, cm dy ni vo laptop mi ln cn in n,

ngi s dng c th kt ni my in trc tip vo mng wifi ca cng

ty. Bng cch ny, ngi dng c kh nng iu khin my in t mi

v tr thng qua laptop.

Ngoi ra, vi phn mm Dropbox (thch hp vi c my s

dng h iu hnh Window v Mac), ngi s dng c th ra lnh cho

my in bng in thoi di ng.

-Thng bo c tin nhn in thoi trn my tnh

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10/16

Android Notifier l mt ng dng hu ch dnh ring cho in

thoi chy h iu hnh ca Google, cho php chuyn chung bo

hiu cuc gi n, tin nhn, bo lch t in thoi ti my vi tnh.

Nh , ngi s dng s khng cn phi lo s ting chungbo hiu "v duyn" ca in thoi ph v s tp trung ca cc ng

nghip. Android Notifier cng l mt minh chng cho s quan tm v

sng to ca Google trn nn tng ca mng wifi.

-Bin in thoi tr thnh thit b pht sng wifi

S dng laptop nh mt b pht wifi tr nn quen thuc.Tuy nhin, khng nhiu ngi c th lm iu vi mt chic in

thoi.

s dng c chc nng ny, in thoi cn c b kha

v ci mt vi phn mm cn thit nh: PDAnet ca iPhone, Wireless

Tether ca h iu hnh Android.

Nh vy, mng wifi gip ngi s dng c th truy cp internet

"mi lc mi ni" qua sng in thoi di ng.

-Xem phim trn mi tivi trong gia nh

y l mt ng dng hu ch, c bit vi nhng ngi m

phim nh. tng chnh l s dng mt thit b nh my vi tnh, my

chi game Playstation hay Xbox lm my ch trung tm kt ni cc

in t trong gia nh. Nh vy, bn s c mt trung tm gii tr

gia nh c kt ni qua mng wifi vi rt nhiu tnh nng a dng.

Phn mm iu khin l Windows Media Mentre, XBMC hay

Google Media Serve dnh cho Window. Mng wifi ni b cho php

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11/16

ngi s dng trao i d liu, truy cp v trnh chiu kho phim ti

nhiu tivi khc nhau.

-Chia s d liu gia cc my tnh

Hin ti, c rt nhiu phng php khc nhau chia s d liu

gia cc my tnh t gn nhau nh mng ni b (LAN) hay internet.

Mng wifi cng l mt cch hu hiu lm vic .

u th ln ca mng khng dy chnh l...khng cn c dy

ni. T , mng wifi gii phng bn khi nhng m dy phin toi,

bin vn phng cng nh cn h ca bn gn gng v hin i hn.Nu bn a thch s dng phn mm Dropbox th y cng l mt

cch chia s d liu rt tin li.

-Nghe nhc "mi lc mi ni"

Kh ging tin ch pht phim, thng qua mng wifi, ngi s

dng c kh nng iu khin v pht nhc trn mi loa c kt ni

vo mng gii tr khng dy ca cn h.

Tin ch ny c t kh lu, c trang b trn cc b pht th

h c v thit b pht nhc khng dy. Tuy nhin, theo cc chuyn gia

th phn mm Airport Express ca Apple c tnh nng ni tri v gip

ngi dng iu khin loa t in thoi iPhone hoc iPod.

-Ti nh t my nh k thut s

Thay v phi ni th nh my nh nh thng thng, th nh

SD Eye-Fi th h mi cho php ti trc tip nh ti my vi tnh.

H iu hnh iOS ca Apple h tr rt tt th nh SD Eye-Fi.

Ngoi ra, ngi s dng cng c th ti trc tip nh ln mng trc

tuyn Facebook hoc trang web nh Flickr v Picasa.

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12/16

-Gip in thoi nhn bit a im

Nhiu in thoi thng minh cho php ngi dng t lch trnh

v in thoi s t ng lm nhng vic nh: m tivi, iu ha nhit

, bt n khi bn ti nh hoc c quan. Nhng mt trong nhngvn ln khi s dng in thoi nh mt thit b iu khin thng

minh l s nhn bit a im.

GPS l mt cng c hu hiu v ph bin trong lnh vc nh

v, tuy nhin xc nh chnh xc ta hay vn phng lm vic ca

bn khng phi l mt cng vic n gin. Hn na, sai s cho php

ca GPS kh ln, v vy nh v bng GPS kh c th xc nh bn

ang ng pha trong hay pha ngoi cnh ca cn h ca mnh. GPS

cng rt ngn pin khin nhiu ngi s dng phi pht s khi m

ng dng ny.

Mng wifi chnh l mt gii php thng minh dnh cho in

thoi. Khi ngi s dng v ti nh, chic in thoi s t ng nhnbit v kt ni vi mng wifi ti nh v thc hin nhng cng vic

c nh sn. ng dng ny hin ch c trn cc my dng h iu

hnh Android.

-ng b ha d liu, nh v m nhc

Cc y vi nm, khi nhng thit b nghe nhc nh iPod mi rai, phng tin duy nht kt ni v ng b ha cc thit b ny l

thng qua cng USB.

Tuy nhin, cng vi s pht trin ca cc chun kt ni cng

mng wifi, ngy nay ngi s dng c th ng b v kt ni thit b

cm tay vi mi my tnh cng nh h iu hnh mt cch d dng.

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13/16

Vic ng b ha in thoi Android vi iTune, Winamp hoc

iPhone vi h iu hnh Linux c th hin mt cch trn tru, n

gin.

Ngoi ra, bn c th s dng mt s phn mm chuyn dngnh: Photosync, Wi-Fi File Explorer, Dazzboard, Android Manager

Wi-Fi v Awesome Drop gip cng vic ng b d liu thun tin

hn.

IV. S pht trin ca Wifi trong tng lai.

Mng khng dy l mt bc t ph ca ngnh mng my tnh. Cng vi

s pht trin ca cng ngh Wi-Fi, mt s lng ln cc thit b Wi-Fi

c bn ra th trng. Tuy nhin, theo cc nh phn tch, tng lai ca

mng khng dy li thuc v WiMax, cng ngh truyn thng khng dy

bng nhiu cch khc nhau.

Ngi ta cho rng ch 5 nm na thi, WiMax s thay th Wi-Fi, cc thit bWiMax s chim lnh th trng ng y nh nhng g ang din ra vi cc

thit b Wi-Fi. Vi WiMax, ngi dng c th truy cp bt c u ging

nh mng in thoi di ng trong khi Wi-Fi ch cho php truy cp nhng

a im c nh c thit b hotspot (ging nh hp in thoi cng cng).

Mng WiMax

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14/16

WiMax (Worldwide Interoperability for Microwave Access) l cng ngh

mng khng dy tun theo chun IEEE 802.16e ca t chc IEEE. S dng

thit b WiMax th ngi dng khng phi lo lng v vn bn quyn.

iu ny ngha l chnh ph cc nc cho php cc hng truyn thng

u gi WiMax v pht trin ra th trng. Do vy, khi truy cp vi WiMax,

ngi dng s khng cn lo ngi vn nhiu sng do cc thit b hay dch

v truyn thng khc. u im ny s gip ngi dng tn dng c nhiu

nng sut ca thit b hn l dng Wi-Fi.

Mt nhc im na ca Wi-Fi c th l im mnh ca WiMax. l cc

tn hiu ca Wi-Fi s b nhiu khi trong bp c l vi ba. Di thng ca Wi-

Fi v ca l vi ba s dng l ging nhau, do nu s dng cc thit b Wi-

Fi trong bp th s gy kh khn cho vic nu n cng nh s dng my

tnh trong khi s dng WiMax s khng gp bt c vn g.

Trong vng 2 ti 5 nm ti, cc thit b WiMax s c sn xut nhanh n

chng mt v kh nng tiu th ca n chc chn cng khng h nh. Xt

ring ti M, ngay sau khi bao ph cc thnh ph ln, WiMax s mt khng

n 1 nm ph trm nt cc vng nng thn.

V. Bo mt trong Wifi.

Wifi ra i, v tip tc ny sinh ra mt vi vn v bo mt.

Thng 9/1999, WEP (Wired Equivalent Privacy) l mt chun cho cc PC

khng dy. WEP c dng trong lp vt l, v lp lin kt d liu. V n

c thit k cung cp mt s bo mt trong WLANs tng t nh trongLANs. WEP s cung cp s bo mt bng cch m ha d liu trong lc

truyn t ni ny n ni khc. Khng ging nh LANs l nhng mng

c xy dng trong cc ta nh, chng c bo v. Cc WLANs c

nhiu nguy c b tn cng hn do s dng sng v tuyn rt d b ngn cn.

Mt l do khc na l trong mt vi tp on, th cc nh qun l khng thay

i cc kha dng chung trong mt thng hay trong mt nm, vic dng mt

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15/16

kha trong thi gian qu lu c th s b nhng k xu c c, v iu ny

l v cng nguy him cho cc tp on.

Nm 2002 vn bo mt ca Wifi c nng ln khi WPA (Wifi

Protected Access) c gii thiu. WPA c mt vi ci tin nh m ha tt

hn. V vic ci t WPA th n gin hn nhiu so vi vic ci t WEP.

V WPA ra i vi 2 dng: Enterprise cho cc tp on, v Personal cho cc

c nhn, gia nh.

Thng 6/2004 th 802.11i ra i, n tr thnh mt chun mi cho Wifi.

802.11i s dng WPA2, so vi WPA th c hai c mt vo tnh nng ging

nhau. Nhng WPA2 tng cng kh nng kh nng m ha d liu hn vi

AES(The Advanced Encryption Standard). WPA2 tng thch vi WPA do

vy ngi dng c th nng cp t WPA ln WPA2 d dng, nhng WPA2

khng tng thch vi cc chun WEP. Cng ging nh WPA, WPA2 cng

c 2 phin bn: Anterprise v Personal.

Ngy nay, cc tp on s mt mng ring o(Virtual Private Network)

gi v nhn nhng thng tin quan trng. VPN s dng Enternet gi v

nhn thng tin bng cch to ra mt kt ni ngm gia 2 ngi s dng.

VPN s m ha d liu trnh cc hacker khi nh cp d liu trong lc

gi. s dng VPN th 2 ngi dng phi s dng cng chung mt giao

thc xc nhn, nu khng n s khng lm vic. Giao thc xc nhn s m

bo cc ngi s dng truy cp mt cch an ton n cc thng tin.

V cn c mt vi cch khc bo v my tnh khng dy ca bn:

iu u tin bn ngh n l thay i nhng thng tin mc nh trn routerkhng dy ca bn. L do l rt nhiu hacker c th truy cp vo c cc

thng tin mc nh ca router bn t nhng cng ty khc, nhng ngi m

kt ni khng dy vi bn. V nh th th s d dng cho cc hacker c

th truy cp c cc thng tin ca bn. V bn nn to mt password

mnh trn my tnh khng dy ngn cc hacker khng truy cp vo

nhng d liu nhy cm.

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16/16

Mt cch na l bn s dng bc tng la, cc bc tng la s dm st v

gii hn giao thng vo v ra trn my tnh ca bn.

Vic ti cc phn mm chng virus vo trong my tnh ca bn cng l mt

cch bo v my tnh ca bn. Bn nn cp nht phn mm chng virus

thng xuyn bi v mi thng c t nht t 10 n 50 virus mi hay cc

worms.

V nu bn ang s dng my tnh khng dy trong khu vc cng cng, bn

nn tt ch chia s ti liu. Bi v nu bn ch chia s ti liu th

cc hacker c th d dng vo c h thng my ca bn. V khi bn

khng cn tip xc vi my tnh na th bn nn turn off n. y l cch

bo mt nht cho cc file my tnh ca bn, v khng mt hacker no c th

vo c mt h thng m n khng cn hot ng.

..

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