WIRELESS NETWORKS

Now a days checking emails, browsing Internet, and other technological works has become easier thanks to mobile devices. We can use those things anywhere at anytime. But still we have to concern about the connectivity. For an example we have to look for a wi-fi hot spot, to connect to the Internet. But with ubiquitous connectivity, this problem will be solved in the near future too.

Wireless networks are the early stage of the ubiquitous connectivity. A wireless network
refers to any network not connected by cables, which is what enables the desired convenience and mobility for the user. When talking about the wireless technology, actually it’s a broad area. These days there are dozens of wireless technologies as well.

  • WiFi
  • Bluetooth
  • ZigBee
  • NFC
  • WiMAX
  • LTE
  • HSPA
  • EV-DO
  • Earlier 3G standards
  • Satellite services

Those are few examples for wireless technologies used now a days. Most wireless technologies operate on common principles, have common trade offs, and are subject to common performance criteria and constraints. So it’s easy to learn a new technology when you know how an old one works.

TYPES OF WIRELESS NETWORKS

A network is a interconnection of two or more computers together. The difference between a normal network and a wireless network is, wireless networks use radio waves as the medium of transmission. There are few types of networks as below. This categorization has done base on the geographical range of the network.

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Though we categorize those wireless technologies under different types, when we want to develop an application, we can’t just restrict to a specific type. We have use different types of technologies like bluetooth, wifi, LTE for better performance and productivity.

PERFORMANCE FUNDAMENTALS OF WIRELESS NETWORKS

Though there are different technologies, there are some similarities between them. Also there are some reasons why a technology can be used for a some task over another technology. Performance, battery life, power consumption, efficiency are some properties to check when we are going to choose a technology.

When talking about the similarities, all technologies have a maximum channel capacity and we can calculate it using the following equation proposed by Claude E. Shannon.

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  • C is the channel capacity and is measured in bits per second.
  • BW is the available bandwidth, and is measured in hertz.
  • S is signal and N is noise, and they are measured in watts.

When looking at the above equation, maximum channel capacity is depending on the bandwidth, signal power and the noise. To get a maximum channel capacity, we have to increase the bandwidth, increase the signal power and try to reduce the noise.

BANDWIDTH

From a previous post we talked about the bandwidth in details. So I’m not going to define the bandwidth here. How ever by simply looking at the above equation, we can say, by increasing the bandwidth when others factors are kept constant, we can increase the maximum channel capacity.

For an example think, if we double the bandwidth, then the maximum channel capacity will be doubled too. That’s what happen in ‘802.11n’ is improving its performance over earlier WiFi standards. They doubled their existing bandwidth and get a doubled maximum channel capacity.

SIGNAL POWER

As we talked earlier, the next factor, which the channel capacity depends on is the signal power. Signal power depends on few factors as well.

  1. The transmit power
  2. The strength of the signal
  3. The distance between the transmitter and the receiver

By increasing the transmit power, increase the strength of the signal and reduce the distance between the transmitter and the receiver, we can get a high power of signal. Then it will increase the maximum channel capacity as well.

MODULATION

Though modulation has no direct impact on the equation, when we talk about the performance of wireless networks, it counts too. To transmit a signal over the radio waves, it should be an analog signal. But we are working with digital signals in our devices. So there should be a conversion of signal from analog to digital and then digital to analog.

  • Digital to Analog conversion : Modulation
  • Analog to Digital conversion : Demodulation

Modem is the device which can be used to this modulation and demodulation process. The algorithm by which the signal is encoded can also have a significant effect. The combination of the alphabet and the symbol rate is what then determines the final throughput of the channel.

So from this post I tried to introduce you, wireless network fundamentals and the factors which determine the performance of a wireless network. Hope now you have a clear idea about it. See you soon with another interesting topic. Thank You!

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