Many people want to know how far wireless signals will go. Knowing this is important for planning a network, as the power of the routers will affect the design of the network, and how much equipment is needed. Different Wi-Fi routers can have very different power levels. Some are much stronger: they have more speaking or transmitting power than others. Some are very good listeners: they have what is called a better receive sensitivity.
These two elements define how well wireless devices will connect, and how far away a receiving Wi-Fi router can be. In some cases, usually with more business or professional oriented equipment you can find the information for transmit power and receive sensitivity. For instance, a light bulb might be 40 watts. A router will have an output power of mW, which is times less! A dBm is a relative measurement using logarithms.
One milliwatt is 0 dBm. This is the scale that many network designers use to calculate if longer wireless links will work. About 25 to 50 meters. About 50 to meters. About 5 to 10 kilometers. About 10 to 20 kilometers or more. Wireless transmitter power is only one half of the connection. This is also known as the receive sensitivity. The receive sensitivity values are generally rated in dBm, and are usually in the range of dBm to dBm. The negative number indicates a very small signal -- tiny fractions of a milliwatt.
Below we have an example of two routers in relatively close range. They have a good connection because the signal strength between them is strong. Below, we can see the same routers, but with more distance between them. In this case, the routers have a weaker connection because the signal is near the limit of what the routers can hear. The speed between the routers will be less. The optimal signal range for outdoor wireless equipment is between dBm and dBm.
This will ensure the connection can maintain the highest bandwidth possible. Wireless routers have different types of antennas. Some routers will have antennas built in, and sometimes the routers will have a choice of antenna you can attach to the router.
There are many specific types of antennas, but three basic types are used most of the time, and will be useful in building a wireless network. The first type of antenna is also the most common--omnidirectional. Using omnidirectional antennas has the benefit of creating connections in any direction. If there is enough signal between nodes, they should connect.
The all-direction strength of these antennas comes with the drawback of transmitting a weaker signal. Since the signal is going in all directions, it spreads out and gets weaker with distance very fast.
If nodes or clients are far away, they may not connect well. Also, if there are only nodes or clients in one direction of the router, then the signals going in the opposite direction are wasted:. The next type of antenna is known as directional--it sends out a signal in a more focused way. There are two main types of directional antennas:. Sector Antenna Focused Antenna Sector antennas send out a pie-shaped wedge of signal - it can be anywhere between 30 degrees and degrees wide.
These are often long, rectangular antennas that are separate or integrated in to a router. A focused antenna sends out a narrow beam of signal - it is normally around 5 to 10 degrees wide, but it can be a little wider as well.
These are often dishes or have a mesh bowl reflecting signal behind them. Using directional antennas has the benefit of increasing the distance a signal will travel in one direction, while reducing it in all other directions. Since the signal is all going one way, the power that would be sent out in all directions with omnidirectional nodes is now focused, increasing the power in that direction.
It can also decrease the interference received at the node. There are fewer signals coming in to the antenna, since the node is only listening to signals from the direction it is pointing. This reduces the signals it needs to sort out, and allows it to focus on other signals more, increasing the quality of those connections.
However, directional antennas also have the drawback of requiring more planning to create links in your neighborhood. Since you are defining and limiting the areas where wireless signals go, you need to think about how those signals cover your neighborhood. If there are areas that are then left out, how will those areas be included in the network? Also, the node has a very powerful signal in a single direction. If omnidirectional units, or lower power units such as laptops, are connecting to the node, they may not connect properly.
The laptop will hear the node very well, but the directional node may not hear the laptop. This will create the situation where it looks like there is a strong signal, but you cannot connect. Networking concepts are important when dealing with wireless. If you are interested in learning more about Wi-Fi and wireless technology, there is a lot of information out there.
There are also excellent documents on Wikipedia about Wi-Fi and wireless signals. Similarly, an Internet search will most likely answer any questions you can think of, as wireless is a very popular technology. For more information on what frequencies are available in your country or regulatory area, please see this article on Wikipedia on wireless channels.
Introduction This document covers the basics of how wireless technology works, and how it is used to create networks. The IEEE sets standards for a range of technological protocols, and it uses a numbering system to classify these standards. A WiFi hot spot is simply an area with an accessible wireless network. The term is most often used to refer to wireless networks in public areas like airports and coffee shops. Some are free and some require fees for use, but in either case they can be handy when you are on the go.
You can even create your own mobile hot spot using a cell phone or an external device that can connect to a cellular network. And you can always set up a WiFi network at home. If you want to take advantage of public WiFi hot spots or your own home-based network, the first thing you'll need to do is make sure your computer has the right gear.
Most new laptops and many new desktop computers come with built-in wireless transmitters, and just about all mobile devices are WiFi enabled. If your computer isn't already equipped, you can buy a wireless adapter that plugs into the PC card slot or USB port. Desktop computers can use USB adapters, or you can buy an adapter that plugs into the PCI slot inside the computer's case. Many of these adapters can use more than one Once you've installed a wireless adapter and the drivers that allow it to operate, your computer should be able to automatically discover existing networks.
This means that when you turn your computer on in a WiFi hot spot, the computer will inform you that the network exists and ask whether you want to connect to it. If you have an older computer, you may need to use a software program to detect and connect to a wireless network.
Being able to connect to the internet in public hot spots is extremely convenient. Wireless home networks are convenient as well. They allow you to easily connect multiple computers and to move them from place to place without disconnecting and reconnecting wires. In the next section, we'll look at how to create a wireless network in your home. If you already have several computers networked in your home, you can create a wireless network with a wireless access point.
If you have several computers that are not networked, or if you want to replace your ethernet network, you'll need a wireless router. This is a single unit that contains:.
A wireless router allows you to use wireless signals or ethernet cables to connect your computers and mobile devices to one another, to a printer and to the internet. Most routers provide coverage for about feet If your home is very large, you can buy inexpensive range extenders or repeaters to increase your router's range.
As with wireless adapters, many routers can use more than one Normally, Once you plug in your router, it should start working at its default settings.
Most routers let you use a web interface to change your settings. You can select:. Security is an important part of a home wireless network, as well as public WiFi hot spots. If you set your router to create an open hot spot, anyone who has a wireless card will be able to use your signal.
Most people would rather keep strangers out of their network, though. Doing so requires you to take a few security precautions. It's also important to make sure your security precautions are current. The idea behind WEP was to create a wireless security platform that would make any wireless network as secure as a traditional wired network.
You also can change other router settings to improve security. For instance, you can set it to block WAN requests to keep the router from responding to IP requests from remote users, set a limit to the number of devices that can connect to your router and even disable remote administration so that only computers plugged directly into your router can change your network settings.
You should also change the Service Set Identifier SSID , which is your network name, to something other than the default so that hackers can't immediately tell what router you are using. And selecting a strong password never hurts. Wireless networks are easy and inexpensive to set up, and most routers' web interfaces are virtually self-explanatory.
For more information on setting up and using a wireless network, check out the links that follow. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. How WiFi Works.
Wireless networks make it easy to connect to the internet wherever you go. Contents What Is WiFi? What Is WiFi? Here's what happens: A computer's wireless adapter translates data into a radio signal and transmits it using an antenna. The planet is becoming increasingly more mobile over the past few years. The worlds conventional ways of networking have proved insufficient to address the challenges raised by our current collective lifestyle.
When users need to be connected by physical cables to a network, their movement is drastically reduced. However, wireless networking does not face such a constraint and enables the network user to move much more freely. To someone who travels daily, this move is apparent. A whole new industry has been developed by wireless networking for voice telephony. Adding mobile access to the telephony mix had profound influences on the voice calls market because callers could be connected to individuals, not computers.
We are at the height of an equally profound shift in networking for computers. Wireless telephony has been popular becuase it allows people to communicate with each other regardless of venue.
For Internet access, modern technology aimed at computer networks promise to do the same. Thus far, Computer network refers to devices, such as computers, fax or even printers connected or linked to each other to communicate and share resources. It makes use of transmission media such as wires and cables. For example, in Local Area Networks LAN , computers are interconnected in a small area such as an office via communication cables.
The main reason for connecting several devices on a network is to share resources. For example, an office has one shared printer. A wireless network allows devices to remain linked to the network yet to roam without any cables unattached. Wi-Fi signals are amplified by access points, meaning a computer can be far from a router but still be linked to the network. The only difference between wireless and wired network is that wired network uses cables to link devices to the Internet or another network, such as laptops or desktop computers.
As opposed to a wireless network, a wired network has several drawbacks. The main downside is that a router is tied to your computer. The most popular wired networks use cables attached to an Ethernet port on the network router and the other end to a computer or other system.
At this point, digging into a particular technology is getting a little ahead of the story, however. Wireless networks share some significant benefits, regardless of how the protocols are built or what kind of information they bring.
Mobility is the most apparent value of wireless networking. Wireless network users can link to existing networks and are then able to travel freely.
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