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Here are some simple concepts that are necessary to your understanding of RF and hence your ability to design, installs, and administers your wireless network. You need to understand the concept of gain, loss, reflection, refraction, diffraction, scattering, absorption, and free space loss.

Gain

Gain describes an increase in a radio frequency signal’s amplitude. Usually, gain is an active process. This means that you can use an external power source (such as an antenna) to amplify a signal, or you can use a high-gain antenna to focus the beam width of a signal to increase its amplitude.

But passive processes can also cause gain. For example, reflected signals (see the upcoming section, “Reflection”) can combine with the main signal to increase the signal’s strength. You must know how to measure gain in your system to find the signal strength at your client or to know whether you’re violating any laws regarding signal strength or power levels.

Loss

Conversely, loss is a decrease in signal strength. Many factors can cause signal loss. For instance, resistance in connectors and friction in a cable can cause signal loss (attenuation), hence the reason for maximum cable runs

When the antenna propagates the high-frequency AC signal into the air, it forms radio waves. These radio waves propagate, or move away, from the source in a straight line in all directions. Just imagine the rock going into the water.

Radio Frequency Spectrum

Frequency Description

Up to 300 Hz Extremely Low Frequency (ELF)

300 Hz–3 kHz Voice frequency

3 kHz–30 kHz Very Low Frequency (VLF)

30 kHz–300 kHz Low Frequency (LF)

300 kHz–3 MHz Medium Frequency (MF)

3 MHz–30 MHz High Frequency (HF)

30 MHz–300 MHz Very High Frequency (VHF)

300 MHz–3 GHz Ultra-High Frequency (UHF)

3 GHz–30 GHz Super High Frequency (SHF)

30 GHz–300 GHz Extremely High Frequency (EHF)

Note: (Hz = Hertz)

Hertz is the unit of frequency. One hertz simply means one cycle (event) per second; 10 Hz means ten cycles (events) per second; and so on. You can apply hertz to any periodic event. For example, the clock speed of your Pentium might be said to tick at 2.2 GHz. The reciprocal of frequency is time (period): a frequency of 1 Hz is equivalent to a period of 1 second, and a frequency of 1 MHz is equal to a period of 1 microsecond. You should know some multiples, as follows:

Term Symbol Equivalence

1 kilohertz kHz 103 Hz or 1,000 Hz

1 megahertz MHz 106 Hz or 1,000,000 Hz

1 gigahertz GHz 109 Hz or 1,000,000,000 Hz

This may or may not make sense, but either way, some examples cannot hurt. For example, standard domestic AC electric power (220v [volt] or 110v voltage) is 50–60 Hz. If you play music on the side, middle C is 261.625 Hz. If you don’t play music but listen to it, FM radio broadcasts are 88–108MHz. The clock speed of the Intel 4004, the world’s first commercial microprocessor, was 104 kHz. Today’s Pentium 4 has a clock speed of around 3 GHz. The Federal Communications Commission (FCC) in the United States as well as other government agencies around the world have made parts of the spectrum available for unlicensed radio networks as long as they meet local regulations. Currently, these bands are the Industrial, Scientific, and Medical (ISM) band (operating at 2.4 GHz) and the U-NII (Unlicensed National Information Infrastructure) band (operating at 5.8 GHz).

Wireless Network uses radio waves in GHz band except of across cable strategy in wired network. There is much kind of wireless products in the markets which is used also in home such as cordless phones, microwave ovens. In 1997, IEEE (Institute of Electrical and Electronics Engineer) released a specification that how WLAN devices manufacturers operates in 2.4GHz of spectrum. This range of spectrum can communicate with the speed of 1 or 2Mb. Because of marketing competition this speed is too much slower than the Ethernet which have range minimum of 10 to 100mb. 1999, 802.11b was developed and in that standard the data can communicate in the speed of 11Mbps. WECA (Wireless Ethernet Compatibility Alliance) was been recognized in that year, which is renamed later by Wi-Fi Alliance. WEP (Wired Equivalent Privacy) was developed which is a mechanism which is use to secure WLAN. On that movement WLAN have to secure in all cases even in the case of government, since on after government have haul up these restrictions.

4G Infrastructure

The future wireless network mean to say the 4G infrastructure will be built with heterogeneous. Combine of wireless LAN and GPRS/UMTS.

We are suspecting that the future wireless network is heterogonous wireless network. Generally it will be the combination of the wired and wireless network. Most of us hesitate to adopt the new technologies and rely on the old. There are many of the debates in the market about the 4th generation, so we summarized the 4th generation (4G) consequences that 4G is going to be very high speed wireless internet

Future Standards will be described for the 4G as per need and modifications will be made by computer scientists.

4G will have over 10 times capacity than the 3G. So the cost per bit will lower to 1/10.

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