UNBOUNDED / UN GUIDED MEDIA

Unbounded / Unguided media or wireless media doesn't use any physical connectors between the two devices communicating. Usually the transmission is send through the atmosphere but sometime it can be just across the rule. Wireless media is used when a physical obstruction or distance blocks are used with normal cable media. The three types of wireless media are:

1)   RADIO WAVES

2) MICRO WAVES

3) INFRARED WAVES

1)   RADIO WAVES:-

Ø It has frequency between 10 K Hz to1 G Hz. 

Ø Radio waves has the following types.

                               i.        Short waves

                             ii.        VHF (Very High Frequency)

                           iii.        UHF (Ultra High Frequency)

                               i.        SHORT WAVES:-

v There are different types of antennas used for radio waves.

v Radio waves transmission can be divided into following categories. 

                               i.        LOW POWER, SINGLE FREQUENCY.

                             ii.        HIGH POWER, SINGLE FREQUENCY

                               i.        LOW POWER , SINGLE FREQUENCY:-

v As the name shows this system transmits from one frequency and has low power out. The normal operating ranges on these devices are 20 to 25 meter.

Ø CHARACTERISTICS LOW POWER , SINGLE FREQUENCY:-

v Low cost

v Simple installation with pre-configured

v 1 M bps to 10 M bps capacity

v High attenuation

v Low immunity to EMI

                             ii.        HIGH POWER, SINGLE FREQUENCY:-

v This is similar to low power single frequency. These devices can communicate over greater distances.

Ø CHARACTERISTICS HIGH POWER, SINGLE FREQUENCY:-

    Moderate cost

    Easier to install than low power single frequency

    1 Mbps to 10 Mbps of capacity

    Low attenuation for long distances

    Low immunity to EMI

2) MICRO WAVES

Ø Micro waves travels at high frequency than radio waves and provide through put as a wireless network media. Micro wave transmission requires the sender to be inside of the receiver.

Following are the types of Micro waves.

     i.        Terrestrial Micro waves

   ii.        Satellite Micro waves

     i.        Terrestrial Micro waves:-

Ø Terrestrial Micro waves are used are used to transmit wireless signals across a few miles. Terrestrial system requires that direct parabolic antennas can be pointed to each other. These systems operate in a low Giga Hertz range.

   CHARACTERISTICS of Terrestrial Micro waves:-

v Moderate to high cost.

v Moderately difficult installation

v 1 M bps to 10 M bps capacity

v Variable attenuation

v Low immunity to EMI

 ii.      Satellite Micro waves

Ø The main problem with aero wave communication is the curvature of the earth, mountains & other structure often block the line of side. Due to this reason, many repeats are required for long distance which increases the cost of data transmission between the two points. This problem is recommended by using satellites.

Ø Satellite micro wave transmission is used to transmit signals throughout the world. These system use satellites in orbit about 50,000 Km above the earth. Satellite dishes are used to send the signals to the satellite where it is again send back down to the receiver satellite. These transmissions also use directional parabolic antenna’ with in line of side.

Ø In satellite communication micro wave signals at 6 GHz is transmitted from a transmitter on the earth through the satellite position in space. By the time signal reaches the satellites becomes weaker due to 50,000 Km distance. The satellite amplifies week signals and transmits it back to the earth at the frequency less than 6 GHz.

   Characteristics Satellite Micro waves:

v High cost

v Extremely difficult and hare installation.

v Variable attenuation.

v Low immunity to EMI

v High security needed because a signal send to satellite is broadcasts through all receivers with in satellite

3) Infrared

Ø Infrared frequencies are just below visible light. These high frequencies allow high sped data transmission. This technology is similar to the use of a remote control for a TV. Infrared transmission can be affected by objects obstructing sender or receiver. These transmissions fall into two categories. 

     i.        Point to point

   ii.        Broadcast

     i.        Point to Point: - Point to point infrared transmission signal directly between two systems. Many lap top system use point to pint transmission. These systems require direct alignment between many devices.

   Characteristics of Point to point:-

v Wide range of cost

v Moderately easy installation.

v 100 k bps to 16 Mb of capacity.

v Variable attenuation.

v High immunity to EMI

   ii.        Broad Cast: - These infrared transmission use sprayed signal, one broad cast in all directions instead of direct beam. This help to reduce the problems of proper alignment and abstraction. It also allows multiple receiver of signal.

   Characteristics of Broad Cast:-

v In expensive.

v Single installation.

v 1M bps capacity.

v Variable attenuation.

Radio frequency

Ø radio frequency, any frequency within the electromagnetic spectrum associated with radio wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space. Many wireless technologies are based on RF field propagation.

Ø These frequencies make up part of the electromagnetic radiation spectrum:

a.   Ultra-low frequency (ULF) -- 0-3 Hz

b.   Extremely low frequency (ELF) -- 3 Hz - 3 kH

c.   Very low frequency (VLF) -- 3kHz - 30 kHz

d.   Low frequency (LF) -- 30 kHz - 300 kHz

e.   Medium frequency (MF) -- 300 kHz - 3 MHz

f.   High frequency (HF) -- 3MHz - 30 MHz

g.   Very high frequency (VHF) -- 30 MHz - 300 MHz

h.   Ultra-high frequency (UHF)-- 300MHz - 3 GHz

i.     Super high frequency (SHF) -- 3GHz - 30 GHz

j.    Extremely high frequency (EHF) -- 30GHz - 300 GHz

Cellular telephone

Ø Cellular telephone, sometimes called mobile telephone, is a type of short-wave analog or digital telecommunication in which a subscriber has a wireless connection from a mobile telephone to a relatively nearby transmitter. The transmitter's span of coverage is called a cell. Generally, cellular telephone service is available in urban areas and along major highways. As the cellular telephone user moves from one cell or area of coverage to another, the telephone is effectively passed on to the local cell transmitter.

Ø A cellular telephone is not to be confused with a cordless telephone (which is simply a phone with a very short wireless connection to a local phone outlet).

Ø The first cellular telephone for commercial use was approved by the Federal Communications Commission (FCC) in 1983. The phone, a Motorola DynaTAC 8000X, weighed 2 pounds, offered just a half-hour of talk time for every recharging and sold for $3,995.

How those it work?

•       Before exploring the maximum range of a cellular telephone, it is first important to understand how they function. In their most basic form, cell phones are radio transponders, converting voice sounds into radio waves, sending them to a local receiver (tower), and also receiving radio waves from that tower. All of the additional functionality of cell phones--text messages, web surfing, digital encoding, and so on--are extras performed by the handset itself, converted into radio waves, and sent as radio signals to the closest tower.

  

Distant cover

•       Before examining the range of phones, it is also important to observe that different types of phones, using different technology, can transmit radio waves different distances. The Global System for Mobile communications (GSM) standard actually limits cell phone transmissions to 35 kilometers, though the phones themselves may be physically capable of transmitting over greater distances. GSM technology is nearly universal in Europe, Asia, and other continents, and is employed by American carriers AT&T and T-Mobile. A different technology common in North America, CDMA (short for Code Division Multiple Access), can achieve significantly greater transmission distances, sometimes up to double the distance of GSM phones. CDMA technology is currently used by American carriers Sprint/Nextel and Verizon, as well as several smaller resellers of their network services

CELLULAR TELEPHONE EQUIPMENT

1)   Samsung Cellular Telephone Stereo Earphones.

2)  Samsung Cellular Telephone Stereo Earphone Adapter.
Adapter allows the use of any stereo earphone/headphone
with a standard 1/8" (3.5mm) stereo plug.

3)  Samsung Cellular Telephone USB Data Cable









 4)  NOKIA Hands-Free In-Ear Cellular Telephone Earset. For use with Nokia 5100/6100 series cellphones. High-sensitivity microphone and earphone. 4 foot cord with clothing clip. Includes instructions. 

5)  Hands-Free In-Ear Cellular Telephone Headset.
Works with any cellular telephone that has a standard 2.5mm
headset jack. High-sensitivity microphone and earphone.
4 foot cord with clothing clip. Includes instructions.

6)  Nokia AC-Operated Battery Charger.
Operates on 120VAC.
For use with Nokia cellphone models

7)  Nokia AC-Operated Battery Charger.
Operates on 120VAC.
For use with Nokia cellphone models

8)  Nokia Cigarette Lighter Adapter/Charger.
For use with Nokia cellphone model

9)  Samsung Cigarette Lighter Adapter/Charger.
Features Short-circuit Protection and Charging LED

10)               Universal Cellular Telephone Holder.
Very well made suction-mount holder quickly attaches
and removes from any glass or flat surface. Fully
adjustable with padded spring-loaded jaws that can
hold almost any item from 1 5/8" to 2 3/4" in width.
Perfect for cellphones, hand-held scanners, ham
and family radios, and GPS units.

  

 What is 3g?

Ø 3G is the third generation of mobile phone standards and technology. 3G supersedes 2G technology and precedes 4G technology. 2.5G was a temporary bridge between 2G and 3G.

Ø 3G technologies enabled faster data-transmission speeds, greater network capacity and more advanced network services.

Ø The first pre-commercial 3G network launched in May 2001 by NTT DoCoMo in Japan. The network was branded as FOMA.

Ø Following the first pre-commercial launch, NTT DoCoMo again made history with the first commercial launch of 3G in Japan on Oct. 1, 2001.

What is 4g?

Ø 4G stands for Fourth Generation of wireless networks. It comes as an improvement over 3G networks and may stand as a successor thereof. While 3G is a suite of several wireless network protocols, 4G is basically one protocol, called WiMAX. There is also the other standard called LTE Advanced, but WiMAX (technically termed 806.16m) is more common.

Many people use 4G and WiMAX interchangeably. 4G standards are WAN standards, i.e. they offer connectivity to devices over a wide area. A 4G network can cover a whole city or country