Computer Network

Computer Tutorial

Introduction to Networking Elementary Terminology of Networks History (Development) of Computer Networks Advantages of Computer Networks Disadvantages of Computer Networks Applications & Uses of Networks ARPANET Internet

Data Communication Data Communication Component Data Transmission Modes Types of Connections Analog Transmission Digital Transmission

Transmission Media Twisted Pair Cable Coaxial Cable Optical Fiber Wireless Communication Radio waves Microwave Infrared

Types of Computer Networks Personal Area Network Local area networks Metropolitan Area Network Wide Area Network Type of Network on the term purpose

Computer Network topologies Bus Topology Ring Topology Star Topology Mesh Topology Tree Topology Hybrid Topology

Networking Devices Hubs Switches Bridges Routers Gateways Wireless Access Point Modems Media Converters Firewalls

» Wireless or Mobile Computing » Evolution of mobile communication systems » Second Generation Networks » Third Generation Networks » Fourth & Fifth Generation Networks » Wireless Transmission Protocols » Multiple Access Techniques » Frequency Division Multiple Access » Time Division Multiple Access » Code Division Multiple Access » Space Division Multiple Access

Computer Network Model Layered Tasks The OSI Model Physical Layer Data Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer TCP/IP Reference Model

Medium Access Methods ALOHA Slotted ALOHA CSMA CSMA / CD Collision-Free Protocols

Error Detection and Correction Types of errors Error Detecting Codes Simple Parity check Two-dimension Parity Check Checksum Cyclic redundancy check Error Correcting Codes

Network Security Network Security Threats Network Security Threats Prevention Why Three Encryption Techniques? Firewall

Computer Networ MCQ

Wireless Transmission Protocols

There are several transmission protocols in wireless manner to achieve different application oriented tasks.

Wireless Local Loop (WLL) and LMDS

Microwave wireless links can be used to create a wireless local loop. The local loop can be thought of as the "last mile" of the telecommunication network that resides between the central office (CO) and the individual homes and business in close proximity to the CO. An advantage of WLL technology is that once the wireless equipment is paid for, there are no additional costs for transport between the CO and the customer premises equipment. Many new services have been proposed and this includes the concept of Local Multipoint Distribution Service (LMDS), which provides broadband telecommunication access in the local exchange.

Bluetooth

» Facilitates ad-hoc data transmission over short distances from fixed and mobile devices
» Uses a radio technology called frequency hopping spread spectrum. It chops up the data being sent and transmits chunks of it on up to 79 different frequencies. In its basic mode, the modulation is Gaussian frequency shift keying (GFSK). It can achieve a gross data rate of 1 Mb/s
» Primarily designed for low power consumption, with a short range (power class-dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device

Wireless Local Area Networks (W-LAN)

» IEEE 802.11 WLAN uses ISM band (5.275-5.825GHz)
» Uses 11Mcps DS-SS spreading and 2Mbps user data rates (will fallback to 1Mbps in noisy conditions)
» IEEE 802.11a standard provides up to 54Mbps throughput in the 5GHz band. The DS-SS IEEE 802.11b has been called Wi-Fi. Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors. Range also varies with frequency band.
» IEEE 802.11g uses Complementary Code Keying Orthogonal Frequency Division Multiplexing (CCK-OFDM) standards in both 2.4GHz and 5GHz bands.

WiMax

» Provides up to 70 Mb/sec symmetric broadband speed without the need for cables. The technology is based on the IEEE 802.16 standard (also called WirelessMAN)
» WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for _xed stations, and 3 - 10 miles (5 - 15 km) for mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 - 300 feet (30 - 100m).
» The 802.16 specification applies across a wide range of the RF spectrum, and WiMAX could function on any frequency below 66 GHz (higher frequencies would decrease the range of a Base Station to a few hundred meters in an urban environment).

Zigbee

» ZigBee is the specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4-2006 standard for wireless personal area networks (WPANs), such as wireless headphones connecting with cell phones via short-range radio.
» This technology is intended to be simpler and cheaper. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.
» ZigBee operates in the industrial, scientific and medical (ISM) radio bands; 868 MHz in Europe, 915 MHz in countries such as USA and Australia, and 2.4 GHz in most worldwide.

Wibree

» Wibree is a digital radio technology (intended to become an open standard of wireless communications) designed for ultra low power consumption (button cell batteries) within a short range (10 meters / 30 ft) based around low-cost transceiver microchips in each device.
» Wibree is known as Bluetooth with low energy technology.
» It operates in 2.4 GHz ISM band with physical layer bit rate of 1 Mbps.

Computer Network

Wireless Transmission Protocols