Wednesday, April 20, 2016

CN - MODULES 3 - Network Media Types

Coaxial cable

Coaxial cable is the kind of copper cable used by cable TV companies between the community antenna and user homes and businesses.
It consists of a center wire surrounded by insulation and then a grounded shield of braided wire. The shield minimizes electrical and radio frequency interference

Twisted-pair cable

A type of cable that consists of two independently insulated wires twisted around one another. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction.

  • UTP & STP

Both shielded twisted pair (STP) and unshielded twisted pair (UTP) have interference blocking capacities. However the way that each one is designed to cancel the interference is different. Interference caused by power lines, radar systems or other high power electromagnetic signals, called noise, can cause an imbalance in the current flowing through the shield or conductors of the cables which interferes with the signal.

STP cables have a conducting shield made of metallic foil encasing the twisted wire pairs, which blocks out electromagnetic interference, allowing it to carry data at a faster rate of speed.

UTP cables are the most commonly used cables for Ethernet connections.

  • Straight-through, crossover, rollover cable













Just remember 2 simple rules:


1. When the devices are same, then crossover cable is used.

2. When devices are different, Straight cable is used.

So for router-to-router we need crossover cable.

FIBRE - OPTIC CABLE

Fibre optic cable are long, flexible, hair-width strands of ultra-pure glass which is capable of transmitting messages modulated onto light waves.

WIRELESS TECHNOLOGY

Electronic products and systems that interact by using electromagnetic energy, to carry information between them, so they can communicate with each other.

 A technology, such as cell phones, that uses radio waves to transmit and receive data. It is used increasingly for data transmission.
  • 802.11 — applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS).

  • 802.11b (also referred to as 802.11 High Rate or Wi-Fi) — an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with a fallback to 5.5, 2 and 1-Mbps) in the 2.4 GHz band. 802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet.

  • 802.11g — applies to wireless LANs and is used for transmission over short distances at up to 54-Mbps in the 2.4 GHz bands

  • 802.11n — 802.11n builds upon previous 802.11 standards by adding multiple-input multiple-output(MIMO). The additional transmitter and receiver antennas allow for increased data throughput through spatial multiplexing and increased range by exploiting the spatial diversity through coding schemes like Alamouti coding. The real speed would be 100 Mbit/s (even 250 Mbit/s in PHY level), and so up to 4-5 times faster than 802.11g

Reference:
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