Module 2.1: Conducted and Wireless Media

prelim topic

Twisted Pair Wire

• One or more pairs of single conductor wires that have been twisted around each other.

• Classified by category - Category 1 through Category 7

• Twisting the wires helps eliminate electromagnetic interference between the two wires

Unshielded Twisted Pair (UTP)

• It is the most common networking media

• Terminated with RJ-45 connectors

• Interconnects hosts with intermediary network devices

• The outer jacket protects the copper wires from physical damage

Shielded Twisted Pair (STP)

• Better noise protection than UTP

• More expensive than UTP

• Harder to install than UTP

• Terminated with RJ45 connectors

• Interconnects hosts with intermediary network devices

• Braided or foil shield provides EMI/RFI protection

Coaxial Cable

• These cables are commonly used in Wireless installations to attach antennas to wireless devices, Cable internet installations for customer premises wiring, or cable television.

• This has a woven copper braid, or metallic foil to act as the second wire in the circuit and as a shield for the inner conductor

• A copper conductor is used to transmit the electronic signals

Ethernet Straight-through

• A type of ethernet cable where BOTH ends are T568A or T568B standard and is used for Hosts to connect to network devices

Ethernet Crossover

• A type of ethernet cable where one end is T568A standard and the other end is T568B standard and is used to connect similar devices to each other: Host-to-Host, Switch-to-Switch, Router-to-Router, etc.

Fiber-Optic Cabling

• A thin glass cable approximately a little thicker than a human hair surrounded by a plastic coating and packaged into an insulated cable

• A photodiode or laser generates pulses of light which travel down the cable and are received by a photoreceptor

• Can carry the highest data rate for the longest distances

• More expensive than twisted pair and coaxial cables

• Immune to EMI

Single-Mode Fiber

• A type of fiber-optic cable that has a very small core, uses expensive lasers, and is reliable for long distance applications

• Very little reflection

Multimode Fiber

• A type of fiber-optic cable that has a large core, uses less expensive LEDs that transmit at different angles, and is good for 10Gbps over 550 meters

• Causes more ray collisions, so you have to transmit slower

Encoding

(Physical Layer Characteristics)

• refers to converting of the stream of bits into a format recognizable by the next device in the network path

• Provides predictable patterns that can be recognized by the next device

Signaling

(Physical Layer Characteristics)

• refers to how the bit values “1” and “0” are represented on the physical medium

• the method will vary based on the type of medium being used

Bandwidth

(Physical Layer Characteristics)

• Is the capacity at which a medium can carry data

• Measures the amount of data that can flow from one place to another in a given amount of time; how many bits can be transmitted in a second

• Physical media properties, current technologies, and the laws of physics play a role in determining this

Latency

(Bandwidth Terminology)

• The amount of time, including delays, for data to travel from one given point to another

Throughput

(Bandwidth Terminology)

• The measure of the transfer of bits across the media over a given period of time

Goodput

(Bandwidth Terminology)

• The measure of usable data transferred over a given period of time

Dispersion

• In fiber-optic cabling, refers to the spreading out of light pulse over time, it means increased loss of strength.

Terrestrial Microwave Transmission

• Land-based, line-of-sight transmission

• Approximately 20-30 miles between towers

• Transmits data at hundreds of millions of bits per second

• Signals will not pass though solid objects

• Popular with telephone companies and business to business transmissions

Satellite Microwave Transmission

• Similar to terrestrial microwave except the signal travels from a ground station on earth to a satellite and back to another ground station

• Can also transmit signals from one satellite to another

• Satellites are classified by how far out into orbit each one is

Cellular Telephones

• Wireless telephone service, also called mobile telephone, cell phone, and PCS

• Used to support multiple users in a metropolitan area (market). The market is broken into cells

• Each cell has its own transmission tower and set of assignable channels

WiMax - Broadband Wireless Systems

• Delivers Internet services into homes, businesses, and mobile devices

• designed to bypass the local loop telephone line

• Transmits voice, data, and video over high-frequency radio signals

• The maximum range of 20-30 miles and transmission speeds in Mbps

• IEEE 802.16 set of standards

Bluetooth

• The specification for short-range communication, typical link range is from 10cm to 10m, but can be extended to 100m by increasing the power

• Used for phones, headsets, notebooks, PDAs, etc.

Wireless Local Area Networks (IEEE 802.11)

• This technology transmits data between workstations and local area networks using high-speed radio frequencies

• Current technologies allow up to 100mbps (theoretical) data transfer at distances up to hundreds of feet

Free Space Optics Communications

• Wireless communication that uses lasers, or more economically, infrared transmitting devices

• Line of sight between buildings

• Typically short distances, such as across the street

• Newer auto-tracking systems keep lasers aligned when buildings shake from wind and traffic

Infrared Transmissions

• These transmissions use a focused ray of light in the infrared frequency range

• Very common with remote control devices, but can also be used for device-to-device transfers, such as PDA to computer

ZigBee

• Based upon IEEE 802.15.4 standard

• Used for low data transfer rates (20-250 Kbps)

• Also uses low power consumption

• primarily used for IoT devices.