Wireless (unb0unded media/unguided media)

Wireless (unb0unded media/unguided media)

- transport electromagnetic wave without physical conductor
- signal broadcasting through air or water
- types of media : microwave, satellite and wireless

~Divided by 3 types:

• terrestrial microwave
• horn
• satellite 

*Wireless is the term that most commonly use to refer to a telecommunications network whose interconnections between nodes is implemented without the use of wires, such as acomputer network.

*Wireless telecommunications networks are generally implemented with some type of information transmission system that uses electromagnetic waves, such as radio waves, for the carrier .

*Wireless communication involves

• radio frequency communication

• microwave communication, for example long‐range line of sight via highly directional antennas or short line‐of‐antennas, short range communication

• infrared (IR) short‐range communication, for example from remote controls or via IRDA

*Applications may involve point‐to‐point communication, point‐to‐multipoint communication, broadcasting ,cellular networks and other wireless networks.

*Devices commonly use wireless networking technologies:

�� portable computers,

�� desktop computers

�� hand‐held computers,

�� personal digital assistants (PDAs),

�� cellular phones,

�� pen‐based computers,

�� pagers, GPS etc.

*Type of Wireless Network:

�� Wireless wide area networks (WWANs)

�� Wireless metropolitan area networks (WMANs)

�� Wireless local area networks (WLANs)

�� Wireless personal area networks (WPANs)

1. TERRESTRIAL MICRO WAVES
~ require line-of-sight transmission and reception microwave
~ the taller the antennas, the longer the sight distance
~ signals are propagate in one direction in a time 
~ consist of repeater which function to increase the distance
~ two types of antenna :

a) Parabolic Dish
~ catching a wide range of waves and directing to a focus
~ higher frequencies for higher data rates
~ 10-60 GHz

b) Horn
~ looks like a gigantic scoop
~ deflected the waves outward in a series of narrow parallel beams
~ received transmission are collected by the scooped shape

2.SATELLITE MICRO WAVES

• 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

3.WiFi

~ transmits computer data over distances using radio waves
~ most commonly used is 802.11 b (11MBps)
~ 802.11 a (54MBps)
~ to communicate over the network, computer must be equipped with a Wi-Fi card
~ types of Wi-Fi card : Wi-Fi PC Cards, USB Adapter, PCI and ISA Adapter .

~~~Recently the IEEE 802.11 standard became more popular as it suites mobile computing devices really well. The IEEE 802.11 standard is another term for WiFi essentially is wireless networking. This standard allows two computers that have wireless NICs to communicate with one another with no strings (wires) attached. This standard makes use of radio waves that are transmitted through the air to communicate. Speeds of either 54 Mbps or 108 Mbps are supported but higher speeds are in the pipeline. 

IEEE (Institute of Electrical and Electronics Engineers). 
The IEEE describes itself as "the world's largest technical professional society; promoting the development and application of electro technology and allied sciences for the benefit of humanity, the advancement of the profession, and the well-being of our members." One of the technologies they have developed is known as Ethernet 802 standard which governs local area networks (wired LANs). Ethernet governs the way in which Data Communications are done across the spectrum.

Difference Between 3G And 4G
4G speeds are meant to exceed that of 3G. Current 3G speeds are topped out at 14Mbps downlink and 5.8Mbps uplink. To be able to qualify as a 4G technology, speeds of up to 100Mbps must be reached for a moving user and 1Gbps for a stationary user. So far, these speeds are only reachable with wired LANs.

different:
1. 3G stands for 3rd generation while 4G stands for 4th generation
2. 3G technologies are in widespread use while 4G compliant technologies are still in the horizon
3. 4G speeds are much faster compared to 3G
4. 3G is a mix of circuit and packet switching network while 4G is only a packet switching network

Advantages of Wi-Fi

• afforting scalability
• ease of installation
• reliability
• mobility

4.CELLULAR PHONE

• 1G

1G is short for first‐generation wireless telephone

technology. This generation of phones and networks is

represented by the brick‐sized analog phones

introduced in the 1980’s. Subsequent numbers refer

to newer and upcoming technology.

• 2G

2G phones use digital networks. Going all‐digital allowed for

the introduction of digital data services, such as SMS and

email. 2G networks and their digital nature also made it more

difficult to eavesdrop on mobile phone calls.

• 3G

3G networks are an in between standard. 3G is seen more as

pre4G instead of a standard of its own. The advantage 3G

networks have over 2G networks is speed. 3G networks are

built to handle the needs of today’s wireless users. This

standard of wireless networks increases the speed of internet

browsing, picture and video messaging, and handheld GPS

use.

• 4G

4G (AKA Beyond 3G) is like the other generations in that its

advantage lies in promised increased speeds in data

transmission. There is currently no formal definition for 4G,

but there are objectives. One of these objectives is for 4G to

become a fully IP‐based system, much like modern computer

networks. The supposed speeds for 4G will be between 100

Mbit/s and 1 Gbit/s.

5.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

6.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

7.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.

The following table shows the main frequency bands used for satellite links.

Frequency Band	Downlink	Uplink
C	3,700-4,200 MHz	5,925-6,425 MHz
Ku	11.7-12.2 GHz	14.0-14.5 GHz
Ka	17.7-21.2 GHz	27.5-31.0 GHz