Standard
Standards are important because they tell different companies that they could follow common ground/rules so that they could be compatible with each other. There are two organizations that make the standards: Institute of Electrical and Electronics Engineers (IEEE), and Internet Engineering Task Force (IETF). IEEE made the standard for WiFi.
Layers of Network
The communication through network could be decided into 7 layers. This is called Open Systems Interconnection (OSI) Reference Model.
Application layer supports the transfer of data between end-users, applications programs and devices. That means user directly interact with this layer. Common protocols are Hypertext Transfer Protocol (HTTP), Hypertext Transfer Protocol Secure (HTTPS), Telnet, Secure Shell (SSH), File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), Simple Mail Transfer Protocol (SMTP), Post Office Protocol 3 (POP3), Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), Network Time Protocol (NTP).
Presentation layer transfer commands from users into universal networking formants. Joint Photographic Experts Group (JPEG), Graphics Interchange Format (GIF),(Tagged Image Format File (TIFF), Moving Picture Experts Group (MPEG), American Standards Code for Information Interchange [ASCII], Extended Binary Coded Decimal Interchange Code [EBCDIC], Secure Sockets Layer (SSL), Hyper Text Transfer Protocol (HTTP), HyperText MarkUp Language (HTML), File Transfer Protocol (FTP) AppleTalk Filing Protocols, JAVA are the formats that computers could understand.
Session layer provides a path for communication between end-user application processes and responses. It’s like the phone-picker at the restaurant. Common protocols for this layer are Common protocols: Lightweight Directory Access Protocol (LDAP) and Remote Procedure Call (RPC), as well as NFS, SQL, and X Windows.
Transport layer defines the way of data transmission and make sure the transmission has high quality. It’s also responsible for flow control, error detection and correction. The most frequently used protocols in this layer are Transmission Control Protocol (TCP), User Datagram Protocol (UDP). TCP is connection-oriented, and it will send confirmation back after receiving information, so it’s slower. UDP is connectionless-oriented, and it will not send confirmation, so it’s faster.
Network layer finds the way for packets in the internet using IP, like a navigation app. Protocols used in this layer are Routing Information Protocol (RIP), Open Shortest Path First (OSPF), Border Gateway Protocol (BGP).
Data link layer is responsible for the physical addressing or MAC (media access control) addresses. It also ensure that the transmission occurs without any mistakes. This layer uses Ethernet, Token Ring, Fiber Distributed Data Interface (FDDI), and Point-to-Point Protocol (PPP), Frame Relay, and Carrier Sense Multiple Access/Collision Detect (CSMA/CD) as protocols.
Finally, physical layer provides the physical or hardware components in a local area network. Common protocols for this layer are Fast Ethernet, RS232, and ATM.
Transmission Media
There are two medias of data transmission: wired, and wireless.
For wired transmission, there are mainly three materials.
Twisted pair wire is cheap, short and easy to install, but not as safe as other wires. It’s usually used in homes. Coaxial wire has moderate cost, and it’s longer and slightly safer than twisted pair. Finally, fiber-optic wire is the longest, safest, most expensive one. Both coaxial and fiber-optic wire need professional installation. Because fiber-optic use light’s reflection to represent 0 and 1, and it can send multiple streams of light at once, so it’s extremely fast (nearly the speed of light).
For wireless transmission, there are also several types.
The standards of wireless networking are 1G (analog), 2G (digital), 3G (circuit-switched telephone service & mobile networking), 4G (LTE, WiMAX) and 5G. 5G involves five new technologies: millimeter waves, small cell (more and smaller cells than 4G), massive MIMO, beam-forming (only to certain nodes), and full duplex.
Devices could connect to home network through WiFi. The radius is smaller and suitable for home.
WiMAX (worldwide interoperability for microwave access) is designed for large distance height speed internet access, and it’s suitable for developing countries.
WSN (wireless sensor networks) usually works depend on measured data and parameters, like environmental sampling, security and surveillance. It requires multiple nodes with different functions like a temperature sensor, a computer and an air-conditioner to operate.
Hardware and Software Components
Here are hardwares in a wireless network.
Wireless Node (PC, laptop, smart phone, printer, game console, tablet, etc. that has the ability to connect wirelessly) is individual device in a wireless network.
Wireless Router / Wireless Access Point (WAP)
Wireless Network Adapter / NIC is an adapter for internet interface.
Wireless Antennas increate the effective communication area.
Wireless Repeater boost or expand the signal.
Radio Waves / Ethernet cable carries signal to WAP.
Switch and/or Hub connect devices to router. It provides signal routes for any two wireless nodes connect to its.
Modem turns digital signal into analog signal, or the other way.
Here are softwares in a wireless network.
DHCP (Dynamic Host Configuration Protocol) is a protocol that automatically assign IP address to connected devices.
Firewall Software controls the data comes in and goes out, so that the computer will not be infected by virus.
Name / SSID (Service Set Identification) differentiates one WLAN from another.
NIC (Network Interface Card) Drivers translates and operates the hardware of the card.
OS (Operating System) manages system resources, all protocols, hardware and applications.
Security Software is access control, anti-spyware, intrusion detection system (IDS), IPS, etc.
WAP (Wireless Application Protocol) is a set of protocols for accessing information over a mobile wireless network.
Web Browser is a type of application software to find, retrieve and display content from the WWW, like Safari and Chrome.
Wireless Network
Compared with wired network, wireless network uses unlicensed radio spectrum, so there is no license fee to pay. It’s easier to set up for normal users, because there’s less wires or cables. It’s more flexible and convenient, because users do not have to worry about the length and arrangement of those wires. Finally, the components are usually cheap and affordable. But wireless network has several disadvantages as well: they are relatively unstable, fragile to interference, less safe and reliable compare to wired network. Some old devices could not connect to wireless network either.
JIHONG ZHAO 