wireless (unb0unded media/unguided media)

• media transport electromagnetic wave without physical conductor.
• signal broadcasting through air or water.
• divided by 3 types:
• terrestrial microwave
• horn
• satellite

TERRESTRIAL MICROWAVE

• require line-of-sight transmission and reception equipment.
• the taller the antennas, the l0nger the sight distance.
• t0wer: 0n hills/m0untins
• signal transmit 0ne way direction at a time
• t0 increase the distance, repeater can be installed with antenna
• 2 types 0f antennas:
• parab0lic dish
• h0rn

PARABOLIC DISH

• parabola
• works like a funnel

HORN

• gigantic scoop
• 0utg0ing transmissi0n are br0adcast up a stem and deflected 0utward in a series 0f narr0w PARALLEL BEAMS by the scooped shape of the horn

SATELLITE

• same principle as terrestrial microwave
• acting ad a super tall antenna and repeater
• single b0unce
• capability is any l0cati0n an earth n0 matter h0w rem0te
• high qualityc0mmunicati0n without requiring a huge investment in gr0und-based infratructure
• same speed = earth
• geosynchronous satellite = orbit speed is based on distance from the planet
• minimum 3 satellite t0 pr0vide full gl0bal transmissi0n
• uplink = transmission from earth to satellite
• d0wnlink = transmission from the satellite to earth

WI-FI

• transmits computer data over distance
• using radio waves
• system follow a standard : 802.11
• create by the institute Electrical and Electronics Engineers (IEEE)
• the system use a license-exempt portion of the radio spectrum
• anyone can set up a WI-FI netw0rk without applying a license or pay for broadcasting rights 

• divided by 2:
• 802.11 a  =  all0w transmits data 0f 54 Mbps
• operating in the 5GHz frequency range
• 802.11 b =  all0w transmits data 0f 11 Mbps
• operating in the 2.4 GHz frequency range
• range = 100-1000 feet

equipment need to set up WI-FI LAN

• WI-FI compatible radio (Wi-Fi card / 802.11b card)
• types of card:
• PC card
• a standard Type II PC Card that slide int0 your laptop's PC Card slot.
• knowns as PCMCIA (Personal Computer Memory Card International Association)
• the protruding end contains a bulit-in antenna - miniature twin diversity antenna (improve coverage)
• USB Adapters
• als0 kn0wn as PCI/ISA bus adapter
• PCI anf ISA Bus Adapters
• these can ne either one-pieces ISA or PCI radios or tw0-piece units that cmoprise a PC Card reader od adapter and a separate Wi-Fi PC Card Radio the slides into the reader.
• compact Flash and other Small-CLient Formats
• designed for smaller PDAs and other mobile computing device
• 802.11b/ Wi-Fi radios can be built onto a Compact Flash format

Advantages of Wi-Fi

• mobility
• reliability
• ease of installation
• afforting scalability

Radio Frequency

• rate of oscillation in the rangr of about 3 kHz to 300 GHz.
• corresponds to the frequenct of radio waves
• alternating currents which carry radio signals
• refer to electrical rather than mechanical oscillations.
• equipment:
• Short Range Devices (SRD), 
• Bluetooth And WLAN (802.11a/b/g/n),
• base stations,
• repeaters,
• 2G/3G/LTE mobile phones,
• PMR radio

Cellular Phones

• kn0wn as mobile phone, cell phone, hand phone.
• device can make and receive telephone cell over a radio link whilst moving around a wide geigraphic area.
• a cordless telephone is used only within the short range of a single, private base station.
• support a wide variety of other services
• text messaging, MMS, email, internet access and s0 0n.

Uplink

• portion of a communication link used for the transmission of signals
• from Earth terminal to Satellite/airborne plateform.
• inverse of a downlink.
• pertaining to GMS and cellulat network.
• the transmission path from the mobile station(cell phone) tp a base station(cell site)
• traffic ang signalling flows within the BSS and NSS
• pertaining to computer network
• connection from data communications equipment  toward the network core
• known as an upstream connection

Downlink

• link from a satellite to a ground station.
• pertaining to cellular network
• transmission path from a cell site to the cell phone.
• traffic and signalling flows within the base station subsystem (BSS) and network switching subsystem (NSS).
• pertaining to a computer networks
• connection from data communications equipment towards data terminal equipment 
• known as downstream connection.