MOODUL C5. TRAADITA VÕRGUNDUS
Raadioside põhimõtted Traadita andmeside Andmed kantakse üle radioeetri Võnkesagedus Amplituud Signaali moduleerimine Kandevsignaali muudetakse vastavalt edastatavale signaalile Amplituudmodulatsioon Sagedusmodulatsioon Kirjeldada raadioside tehnoloogiad Kirjeldada raadioside põhistandardid Teada raadio- ja mobiilvõrkudele iseloomulike probleeme Teada raadiosidest tulenevaid piiranguid Amplituudmodulatsiooni kasutamisel peab olema kandevsignaal suurema amplituudiga kui infot edastav signaal. Vastasel korral signaali moduleerimine pole võimalik. Sagedusmodulatsiooni korral peab olema kandevsignaali sagedus piisavalt suur kirjeldamaks ülekantavat signaali. Reedel on lihtne: mida kõrgem sagedus, seda suurem saab olla ühes ajahetkes ülekantav info hulk. Samas on kõrgematel sagedustel signaali leviala väiksem. Samuti on kõrgetel sagedustel leviv signaal tundlikum füüsilistele takistustele (seinad, puud jne). Mida suurem on ülekandesagedus, seda suurem on võrgu läbilaskevõime ning seda väiksem on võimalik leviala. Suurtel kandevsagedustel töötavad raadiovõrgud on väga tundlikud füüsiliste takistuste suhtes.
Raadioside põhimõtted Kirjeldada raadioside tehnoloogiad Kirjeldada raadioside põhistandardid Teada raadio- ja mobiilvõrkudele iseloomulike probleeme Teada raadiosidest tulenevaid piiranguid Amplituudmodulatsiooni kasutamisel peab olema kandevsignaal suurema amplituudiga kui infot edastav signaal. Vastasel korral signaali moduleerimine pole võimalik. Sagedusmodulatsiooni korral peab olema kandevsignaali sagedus piisavalt suur kirjeldamaks ülekantavat signaali. Reedel on lihtne: mida kõrgem sagedus, seda suurem saab olla ühes ajahetkes ülekantav info hulk. Samas on kõrgematel sagedustel signaali leviala väiksem. Samuti on kõrgetel sagedustel leviv signaal tundlikum füüsilistele takistustele (seinad, puud jne). Mida suurem on ülekandesagedus, seda suurem on võrgu läbilaskevõime ning seda väiksem on võimalik leviala. Suurtel kandevsagedustel töötavad raadiovõrgud on väga tundlikud füüsiliste takistuste suhtes.
Raadioside põhimõtted Vabad sagedusalad Väljundvõimsuse piiramine Kuna ühes ja samas sagedusvahemikus töötavad võrgud võivad üksteist segada, siis püütakse vahel tahtlikult leviala piirata. Nii on mitmetele tehnoloogiatele seatud piirangud maksimaalsele väljundvõimsusele.
Raadioside põhistandardid GSM võrgud töötavad 900 MHz? või 1800 MHz? vahemikes ning võimaldavad andmesidet kiirusega kuni 114 kbps. EDGE toetusega võrgud võimaldavad andmesidekiirust kuni 473,6 kbps. http://en.wikipedia.org/wiki/4G http://en.wikipedia.org/wiki/3g http://www-new.telenor.com/no/resources/images/045-058_Architecture-4G-MobileCom_tcm26-36773.pdf
Raadioside põhistandardid GSM (Global System for Mobile Communication) 850 MHz kuni 1900 MHz GPRS (General Packet Radio Service) 114kbps EDGE (Enhanced Data Rates for GSM Evolution) 473,6kbps UMTS (Universal Mobile Telecommunications System) 3G 14,4Mbps 4G 1Gbps GSM võrgud töötavad 900 MHz? või 1800 MHz? vahemikes ning võimaldavad andmesidet kiirusega kuni 114 kbps. EDGE toetusega võrgud võimaldavad andmesidekiirust kuni 473,6 kbps. http://en.wikipedia.org/wiki/4G http://en.wikipedia.org/wiki/3g http://www-new.telenor.com/no/resources/images/045-058_Architecture-4G-MobileCom_tcm26-36773.pdf
Raadioside põhistandardid UMTS http://www-new.telenor.com/no/resources/images/045-058_Architecture-4G-MobileCom_tcm26-36773.pdf UTRAN (UMTS Terrastrial Radio Access Network) SGSN (Serving GPRS Support Node) GGSN (Gateway GPRS Support Node) RNC (Radio Network Controller) Node b – base station WCDMA (Wideband Code Division Multiple Access) The latter is composed of the Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN) which are interconnected via an IP network. The SGSN keeps track of the location of individual mobile stations and performs security functions and access control. The GGSN encapsulates packets received from external IP networks and routes them toward the SGSN. The UTRAN consists of the Radio Network Controller (RNC) and Node B (i.e. the base station) connected by an asynchronous transfer mode network. The RNC is in charge of the overall control of the logical resources provided by Node Bs. A UE communicates with the Node B through a radio interface based on Wideband Code Division Multiple access (WCDMA) technology. Inside the wired portion of the network, The Universal Mobile Telephone Service (UMTS) adopts Asynchronous Transfer Mode (ATM), while in the radio portion it makes use of the Wideband Code Division Multiple Access (WCDMA) system. With WCDMA each communication happens by modulating a frequency obtained by modulating the radio signal through a pseudo-random signal. Along the same frequency multiple stations can operate, provided that different pseudo-random sequences have been chosen during modulation. Phone signals are exchanged with the Frequency Division Duplex (FDD) technique, exploiting the same frequency both for transmission and for reception, but obviously in different time slots. The superimposed modulation is QPSK. This is a phase modulation where signals can differ at least by 90° and can transmit 4 symbols by encoding 2 bits upon each transmission. The employed frequencies fall between 1900 MHz and 2200 MHz. Device power is about 20W for BTS and less than 250mW for terminals, whose power is controlled by the BTS, which configure it at the minimum value needed for a correct communication.
Raadioside põhistandardid WPAN (Wireless Personal Area Networks) IEEE 802.15.1 (Bluetooth) Ulatus 10m 2,4GHz Piconet Star tehnoloogia seade master või slave 1 master ja kuni 7 slave seadet Master võtab ühendust slave seadmega Slave võib andmeid üle kanda kui tema poole on pöördutud 3Mbps Wireless Personal Area Networks A WPAN is a short-range (typically, transmission range is limited to 10 m), low-cost and low-power consumption technology. Unlike UMTS, WPAN operates in the unlicensed Industrial, Scientific and Medical (ISM) frequency band at 2.4 GHz. The IEEE 802.15 working group is standardizing different versions of WPAN: • IEEE 802.15.1 (Bluetooth) [5] • IEEE 802.15.3 [6] 2.1.1 IEEE 802.15.1 (Bluetooth) The Bluetooth specification has been made the IEEE 802.15.1 standard [5]. Hence, Bluetooth and IEEE 802.15.1 are synonymous. Throughout this paper, we use the term Bluetooth. Two or more Bluetooth devices sharing the same frequency-hopping sequence form a piconet, which is a star topology. The smallest unit of a WPAN is known as piconet. Within a piconet, a Bluetooth device can play either one of the two roles: master or slave. Each piconet may only contain one master device and up to seven slave devices. Communication in a piconet is organized in such a way that the master device polls each slave according to a certain polling algorithm. A slave device is only allowed to transmit after being polled by the master device as depicted in Figure 2. Different piconets employ different frequency-hopping sequences to prevent mutual interferences. Bluetooth offers gross bit rates of up to 3 Mb/s. Bluetooth defines not only a radio interface, but a whole communications stack that allows devices to find each other and advertise the services they offer. The core Bluetooth protocol stack, which consists of Layer 1 and 2, is illustrated in Figure 5. Bluetooth Network Encapsulation Protocol (BNEP) provides an Ethernet-like interface to the upper layer. Communications at the Logical Link Control and Adaptation Protocol (L2CAP) layer in a piconet can only be
Raadioside põhistandardid Jagatud klasideks (class 2 2,5mW ja 10m, class 3 1mW ja 1m) Wireless Personal Area Networks A WPAN is a short-range (typically, transmission range is limited to 10 m), low-cost and low-power consumption technology. Unlike UMTS, WPAN operates in the unlicensed Industrial, Scientific and Medical (ISM) frequency band at 2.4 GHz. The IEEE 802.15 working group is standardizing different versions of WPAN: • IEEE 802.15.1 (Bluetooth) [5] • IEEE 802.15.3 [6] 2.1.1 IEEE 802.15.1 (Bluetooth) The Bluetooth specification has been made the IEEE 802.15.1 standard [5]. Hence, Bluetooth and IEEE 802.15.1 are synonymous. Throughout this paper, we use the term Bluetooth. Two or more Bluetooth devices sharing the same frequency-hopping sequence form a piconet, which is a star topology. The smallest unit of a WPAN is known as piconet. Within a piconet, a Bluetooth device can play either one of the two roles: master or slave. Each piconet may only contain one master device and up to seven slave devices. Communication in a piconet is organized in such a way that the master device polls each slave according to a certain polling algorithm. A slave device is only allowed to transmit after being polled by the master device as depicted in Figure 2. Different piconets employ different frequency-hopping sequences to prevent mutual interferences. Bluetooth offers gross bit rates of up to 3 Mb/s. Bluetooth defines not only a radio interface, but a whole communications stack that allows devices to find each other and advertise the services they offer. The core Bluetooth protocol stack, which consists of Layer 1 and 2, is illustrated in Figure 5. Bluetooth Network Encapsulation Protocol (BNEP) provides an Ethernet-like interface to the upper layer. Communications at the Logical Link Control and Adaptation Protocol (L2CAP) layer in a piconet can only be
Raadioside põhistandardid WLAN (Wireless LAN) standardid 14 kanalit http://en.wikipedia.org/wiki/IEEE_802.11#802.11n http://en.wikipedia.org/wiki/IEEE_802.11n http://en.wikipedia.org/wiki/802.11 Levi bg versioonil sees keskmiselt 38m ja väljas 140m, n versioonil sees 70m ja väljas 250m http://en.wikipedia.org/wiki/802.11g 54Mbps, 2,4GHz, 14 channelit, tundlik häiretele, kuna samas alas toimivad väga erinevad seadmed http://en.wikipedia.org/wiki/IEEE_802.11n-2009 N Võimaldab kuni 600Mbps ühendust (reaalselt kuni 450Mbps, tavalise sülearvuti puhul – 2 antenni – kuni 300Mbps), mitme samaaegse stream-i kasutamisega. Streamide arv on maks 4 ja sõltub antennide arvust. Maksimum on 3 antenni reaalselt. 802.11n on ka 5GHz konfitav aga sedamed peavad toetama. Selle konfiga saab maksimaalse kiiruse.
Raadioside põhistandardid WLAN turvalisus Autentimine Personal PSK (pre-shared key) – jagatud võti Enterprise 802.1x EAP (domeenikasutajana, sertifikaadiga, kiipkaardiga) Krüpteerimine WEP (Wired Equivalent Protection ) 64- või 128-bitine krüpteering, staatiline võti, võtme haldus puudub WPA (Wi-Fi Protected access), TKIP (Temporal Key Integrity Protocol) krüpteering, võtme haldus WPA2 parendatud versioon WPA-st, toetab AES (Advanced Encryption Standard) krüpteeringut, nõuab rohkem protsessori jõudlust http://en.wikipedia.org/wiki/Wpa2#WPA2 http://www.openxtra.co.uk/articles/wpa-vs-80211i Kui keegi sooritab kuriteo interneti kaudu siis algab kurjategija tuvastamine kasutades IP aadressi ja selle järgi nõutakse ISP-lt kliendi andmed. Enda varjamiseks võib kurjategija kasutada turvamat WiFi võrku ja panna võrgu omaniku raskesse olukorda. Võrgu kaitseks on 2 komponenti: autentimine, et ressurssidele juurde pääseda ja krüpteerimine, et kaitsta infot pealtkuulamise eest. WPA-EAP Extensible Authentication Protocol. different methods: ■ PEAP-MS-CHAPv2 to enable users to connect to a wireless network using their domain credentials ■ Certificates stored on the user’s computers ■ Certificates stored on smart cards Wired Equivalent Protection (WEP) Available using either 64-bit or 128-bit your network. ■ Wi-Fi Protected Access (WPA) WPA is the successor to WEP, offering signifi cantly better protection. WPA is not as universally supported as WEP, however, so if you have non-Windows wireless clients or wireless devices that do not support WEP, you might need to upgrade them to support WPA. Windows 7 supports both WPA-Personal and WPA-Enterprise, as follows: • WPA-PSK (for pre-shared key), also known as WPA-Personal, is intended for home environments. WPA-PSK requires a user to enter an 8- to 63-character passphrase into every wireless client. WPA converts the passphrase to a 256-bit key. • WPA-EAP (Extensible Authentication Protocol), also known as WPA-Enterprise, relies on a back-end server running Remote Authentication Dial-In User Service (RADIUS) for authentication. The RADIUS server can then authenticate the user to the AD DS or by verifying a certifi cate. WPA-EAP enables very fl exible authentication, and Windows 7 enables users to use a smart card to connect to a WPA-Enterprise protected network. ■ WPA2 WPA2 (also known as IEEE 802.11i) is an updated version of WPA, offering improved security and better protection from attacks. Like WPA, WPA2 is available as both WPA2-PSK and WPA2-EAP. ■ Open with 802.1X 802.1X is a network authentication method traditionally used for wired networks. When network administrators require 802.1X authentication for a wired network, the network switch communicates with an authentication server when a new user connects an Ethernet cable to the network. If the user is authenticated, the switch grants them access to the network. With Open With 802.1X wireless security, the wireless access point does not require any encryption. However, once a wireless client has connected to the network, the computer must authenticate using 802.1X before they will be granted network access. This security type provides authentication, but not encryption. WPA2 are available in two modes: Personal: a pre-shared key (PSK) is used for authentication and you provide the same key to each user. It is designed for small office/home office (SOHO) infrastructure mode networks. Enterprise: an 802.1x authentication server distributes individual keys to users that have a “wireless” designation. It is designed for medium and large infrastructure mode networks. Discuss the use of these security protocols. 802.11 open system: no authentication and no encryption. This is not recommended, unless there are other device that provides authentication. 802.11 WEP: no key management and weakness in encryption. This is still widely used, although not recommended. Typically used in public access, such as coffee shops or airports. For more information on WEP and its flaws, refer to: http://go.microsoft.com/fwlink/?LinkID=154212 WPA, WPA2: personal and Enterprise modes. Personal uses PSK and Enterprise uses RADIUS based authentication using 802.1X. WPA-Enterprise or WPA2-Enterprise is the recommended security protocols for large organizations, whereas WPA-Personal or WPA2-Personal may be the choice for home or small offices. 1.WPA2 is the improved version of WPA 2.WPA only supports TKIP encryption while WPA2 supports AES 3.Theoretically, WPA2 is not hackable while WPA is 4.WPA2 requires more processing power than WPA Read more: Difference Between WPA and WPA2 | Difference Between | WPA vs WPA2 http://www.differencebetween.net/technology/difference-between-wpa-and-wpa2/#ixzz1K8ROTdpr Briefly explain that in addition to implementing authentication and encryption, you can also use the following methods to mitigate risks to your wireless network: Firewalls: one solution to address wireless AP vulnerability is to place the wireless APs outside your network firewalls. Closed networks: some wireless APs support a closed network mode in which the wireless AP does not advertise its SSID. SSID spoofing: you can use special software that generates numerous wireless AP packets that broadcast false SSIDs. Media access control (MAC) address filtering: most wireless APs support MAC address restrictions.
Raadioside põhistandardid WLAN turvalisus Tulemüür SSID peitmine SSID võltsimine (spoofing) Media access control (MAC) aadressi filtreerimine 802.1X seadmete kasutamine koos RADIUS autentimisega Firewalls: one solution to address wireless AP vulnerability is to place the wireless APs outside your network firewalls. Closed networks: some wireless APs support a closed network mode in which the wireless AP does not advertise its SSID. SSID spoofing: you can use special software that generates numerous wireless AP packets that broadcast false SSIDs. Media access control (MAC) address filtering: most wireless APs support MAC address restrictions. RADIUS autentimine: TCP/IP Fundamentals for Microsoft Windows: http://www.microsoft.com/downloads/en/confirmation.aspx?FamilyID=c76296fd-61c9-4079-a0bb-582bca4a846f&displaylang=en
Raadiovõrk Ad-hoc võrk Infrastruktuuri võrk Võrgu kliendid Seadmetevaheline raadio- võrk ilma juurdepääsu- Punktita Seadmed ühenduvad otse (Peer-to-peer ühendus) Infrastruktuuri võrk Seadmed ühenduvad läbi juurdepääsupunkti (Access Point) Võrgu kliendid Eesmärgid: Kirjeldada juhtmevaba kohtvõrgu põhikomponendid Teada erinevate tehnoloogiate ühilduvust Kirjeldada satelliidipõhise võrgu põhikomponendid Juhtmevaba kohtvõrgu keskseadet nimetatakse tugijaamaks ehk juurdepääsupunktiks (ik AP, AccessPoint?), mis tagab traadita võrgu leviala. Tugijaam võimaldab enda külge ühenduda paljudel WLAN seadmetel ja ta on kaühenduslüli WLAN ja LAN (Local Area Network) võrgu vahel, võimaldades ühendada WLAN võrgu LAN võrguga. Tugijaam võib endas sisaldada võrgusilda (ik bridge) või marsruuterit (ik router). Samuti võib tugijaam jagada internetiühendust ning ühendada erinevaid LAN võrke. Juhtmevaba võrgu klient on selline seade, mis omab vastavat raadiovõrgu liideskaarti. Tavaliselt on selleks mobiilne tööjaam – sülearvuti, pihuarvuti. Kuid klientseade võib olla ka näiteks triipkoodi lugeja jms. Klientseadmete omavaheline andmevahetus toimub läbijuurdepääsupunkti. Sellist suhtlust nimetatakse infrastruktuurrežiimiks.
Raadiovõrk Raadiovõrkude ühilduvus Satelliitsidevõrk 802.11bgn 802.15 mikrolaineahi Ei ühildu kuigi sagedused samad Satelliitsidevõrk Maapealne tugijaam ehk saatejaam + vastuvõtuseade 20GHz Taldrik LNA (low-noise amplifier) võimendi transiiver 1GBps Satelliit Suured viivitused Kallis ühendus Omavahel on reeglina ühilduvad 802.11b ja 802.11g seadmed. See tähendab, et vajadusel on 802.11g võrgu seadmed võimelised töötama 802.11b seadmetena. 802.11a seadmed töötavad aga teisel kandevsagedusel ning 802.11b ja 802.11g võrkudega ühendumiseks peab seadmetel olema eraldi tugi. Bluetooth võrguseadmed 802.11 võrkudega ei ühildu ning nende võrkude kasutamiseks peab seametel olema eraldi 802.11 võrkude tugi. Niisiis ei ole mitmed 2,4 GHz? sagedusalas töötavad tehnoloogiad omavahel ühilduvad, kuid kuna need tehnoloogiad töötavad samas sagedusalas, võivad need segada üksteise tööd. Kõige parem näide 2,4 GHz? sagedusalas töötavatest mitteühilduvatest seadmetest on muuhulgas mikrolaineahi. Mikrolaineahi ei ole mitte mingil andmesidega seotud, kuid ometi kasutab toidu soendamiseks 2,4 GHz? laineid ning kuna mikrolaineahju võimsus on väga suur, siis võib see olulisel määral segada 2,4 GHz? sagedusalas töötavaid andmeside seadmeid. Sateliidipõhise võrgu loomiseks on vajalik maapealne tugijaam (saatejaam), vastuvõtuseade (mobiiltelefon, SAT-TV vastuvõtuseade, võrguseade jne) ning geostatsionaarsel orbiidil tiirlevat sateliiti. Sellised sateliidid tiirlevad ümber maakera selliselt, et on maa pealt vaadates alati ühe ja sama koha peal. Sateliidipõhised võrgud on mõeldud geograafiliselt kaugete punktide ühendamiseks või kasutamiseks piirkondades, kus vastav maapealne infrastruktuur puudub (näiteks Lähis-Ida, Aafrika jne). Selliseid võrke iseloomustab suur latentsus (ehk viide) ning kõrged ülekandetasud. An Earth station is the term used to describe the combination of antenna, low-noise amplifier (LNA), down-converter, and receiver electronics, which are used to receive a signal transmitted by a satellite. They consist of a transceiver device, usually full-duplex, typically operating in the Ka band (i.e. around 20 GHz) and also equipped with a modem that operates using narrowband communications. A Very Small Aperture Terminal (VSAT) is a 2-way satellite ground station with a dish antenna that is smaller than 3 meters, as compared to around 10 meters for other types of satellite dishes. It consists of two parts, a transceiver that is placed outdoors in direct line of sight to the satellite and a device that is placed indoors to interface the transceiver with the end user's communications device, such as a PC. Earth Stations used by very big organisations can reach communication speeds close to 1 Gbit/sec; though, this may be limited by contracts to values as low as 120 Kbits/sec. High latency is a common drawback to satellite communications. It is the time needed for a signal transmitted from one Earth station to be received via satellite by another Earth station. The delay due to the radio trunk is usually around 250 ms.
Mobiiliaparaatide protokollid GPRS WAP (Wireless Application Protocol) Veebilehitsemiseks mobiilis WML (Wireless Markup Language) Mobiilne IP Bluetooth http://en.wikipedia.org/wiki/Mobile_ip Kirjeldada terminalseadmete põhilised protokollid: Mobile IP, Wireless Application Protocol (WAP) Mõista iga protokolli rakenduspiirkonda Mobile IP on tehnoloogia, mis võimaldab kasutajatel liikuda ühest võrgust teise säilitades üht kindlat IP aadressi. See tehnoloogia baseerub sellel, et igale mobiilsele seadmele antakse koduaadress ning juhul kui seade liigub koduvõrgust välja, siis annab seade oma koduvõrgu agendile teada oma uue asukoha ning koduvõrgu agent saadab üle virtuaalse tunneli seadmele mõeldud paketid uude asukohta edasi. Nii on võimalik vältida probleeme, mis tekivad süsteemides, kus on nõutav ühelt ja samalt IP aadressilt pöördumine. WAP (ik Wireless Application Protocol) on tehnoloogia mõeldud mobiiltelefonide ja pihuarvutite kaudu interneti kasutamiseks. WAP lehitseja on sarnane arvutis kasutatavale veebilehitsejale, kuid WAP leheküljed on koostatud (või porditud) WML (ik Wireless Markup Language) keeles. WAP leheküljed arvestavad mobiiltelefonide ja pihuarvutite piirangutega (väiksem ekraan ja andmeedastuskiirus jne). WAP tehnoloogia abil on võimalik kasutada pea kõiki enamlevinud internetiteenuseid. The General Packet Radio System (GPRS) protocol enables the same level of mobility as a cellular phone. The Wireless Application Protocol (WAP) protocol is used for Internet-like browsing through a mobile phone. The Mobile IP protocol is used to connect IP-based mobile terminals to the network. The Bluetooth protocol is used to interconnect mobile devices operating close to one another, rather than manage mobility. The GPRS protocol, as already illustrated in the previous sections, is used to connect portable PCs to the network through the telephone line; this is useful in those situations in which a wired (telephone) connection is not available. Billing typically depends on the amount of data exchanged and is somewhat expensive. For GPRS a PC is used, on the other hand, for WAP only the cellular phone id is used. But beware! We are not dealing with a simple HTML substitute needed to adapt contents to a smaller screen. WAP is a much more complicated protocol, based on two layers and enabling more complex applications with respect to those available today and which did not encounter a great success on mobile phones. The Mobile IP protocol provides users of mobile IP (both IPv4 and IPv6) devices the freedom to roam beyond their home subnet while consistently maintaining their home IP address. MobileIP works by associating two distinct IP addresses with a single mobile station. One of the two addresses, known as HomeIP, is statically assigned to the station, and is used by peers to contact it. The other address is dynamically assigned from the cell with which the station interacts. When moving, the mobile station can reach an area covered by a different cell: in such case, the dynamic address changes and is communicated to the device responding to the HomeIP. All correspondent packets normally arrive at this station, which modifies the packet by inserting a new IP header with its own address as sender and the dynamic address as receiver (operation also known as ‘IP in IP encapsulation’). The above operation allows the packet crossing the network by avoiding routing problems. Once at the mobile station, the external IP header is removed; the original packet is thus extracted and handed to the receiving application. For the return packet the procedure is perfectly symmetrical: the header added to the packet has the dynamic IP address in the source address field and the HomeIP address in the destination address field. This guarantees that the packet arrives at the static location, which removes the external header before further forwarding the packet.
Kasutatud kirjandus http://ecdl.ee/EUCIP_eksami_sooritajale.html http://iva.e-uni.ee/IVA/EITS/ TCP/IP Fundamentals for Microsoft Windows: http://www.microsoft.com/downloads/en/confirmation.aspx?FamilyID=c76296fd-61c9-4079-a0bb-582bca4a846f&displaylang=en http://en.wikipedia.org/wiki/Wpa2#WPA2 http://en.wikipedia.org/wiki/Mobile_ip http://en.wikipedia.org/wiki/IEEE_802.11#802.11n http://www-new.telenor.com/no/resources/images/045-058_Architecture-4G-MobileCom_tcm26-36773.pdf http://www.openxtra.co.uk/articles/wpa-vs-80211i http://en.wikipedia.org/wiki/Mobile_ip Kirjeldada terminalseadmete põhilised protokollid: Mobile IP, Wireless Application Protocol (WAP) Mõista iga protokolli rakenduspiirkonda Mobile IP on tehnoloogia, mis võimaldab kasutajatel liikuda ühest võrgust teise säilitades üht kindlat IP aadressi. See tehnoloogia baseerub sellel, et igale mobiilsele seadmele antakse koduaadress ning juhul kui seade liigub koduvõrgust välja, siis annab seade oma koduvõrgu agendile teada oma uue asukoha ning koduvõrgu agent saadab üle virtuaalse tunneli seadmele mõeldud paketid uude asukohta edasi. Nii on võimalik vältida probleeme, mis tekivad süsteemides, kus on nõutav ühelt ja samalt IP aadressilt pöördumine. WAP (ik Wireless Application Protocol) on tehnoloogia mõeldud mobiiltelefonide ja pihuarvutite kaudu interneti kasutamiseks. WAP lehitseja on sarnane arvutis kasutatavale veebilehitsejale, kuid WAP leheküljed on koostatud (või porditud) WML (ik Wireless Markup Language) keeles. WAP leheküljed arvestavad mobiiltelefonide ja pihuarvutite piirangutega (väiksem ekraan ja andmeedastuskiirus jne). WAP tehnoloogia abil on võimalik kasutada pea kõiki enamlevinud internetiteenuseid. The General Packet Radio System (GPRS) protocol enables the same level of mobility as a cellular phone. The Wireless Application Protocol (WAP) protocol is used for Internet-like browsing through a mobile phone. The Mobile IP protocol is used to connect IP-based mobile terminals to the network. The Bluetooth protocol is used to interconnect mobile devices operating close to one another, rather than manage mobility. The GPRS protocol, as already illustrated in the previous sections, is used to connect portable PCs to the network through the telephone line; this is useful in those situations in which a wired (telephone) connection is not available. Billing typically depends on the amount of data exchanged and is somewhat expensive. For GPRS a PC is used, on the other hand, for WAP only the cellular phone id is used. But beware! We are not dealing with a simple HTML substitute needed to adapt contents to a smaller screen. WAP is a much more complicated protocol, based on two layers and enabling more complex applications with respect to those available today and which did not encounter a great success on mobile phones. The Mobile IP protocol provides users of mobile IP (both IPv4 and IPv6) devices the freedom to roam beyond their home subnet while consistently maintaining their home IP address. MobileIP works by associating two distinct IP addresses with a single mobile station. One of the two addresses, known as HomeIP, is statically assigned to the station, and is used by peers to contact it. The other address is dynamically assigned from the cell with which the station interacts. When moving, the mobile station can reach an area covered by a different cell: in such case, the dynamic address changes and is communicated to the device responding to the HomeIP. All correspondent packets normally arrive at this station, which modifies the packet by inserting a new IP header with its own address as sender and the dynamic address as receiver (operation also known as ‘IP in IP encapsulation’). The above operation allows the packet crossing the network by avoiding routing problems. Once at the mobile station, the external IP header is removed; the original packet is thus extracted and handed to the receiving application. For the return packet the procedure is perfectly symmetrical: the header added to the packet has the dynamic IP address in the source address field and the HomeIP address in the destination address field. This guarantees that the packet arrives at the static location, which removes the external header before further forwarding the packet.