Wireless Networking. Technology. From Principles to Successful Implementation. Steve Rackley. AMSTERDAM • BOSTON • HEIDELBERG • LONDON. INTRODUCTION TO WIRELESS. NETWORKS. Up to a point, it's quite possible to treat your wireless network as a set of black boxes that you can turn on and. tutorial helps to develop an overview on the existing trends of wireless .. communication with other wired and wireless networks as well as support for.
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Introduction. Wireless technology has helped to simplify networking by enabling multiple computer users to simultaneously share resources in a home or. IEEE Wireless Personal Area Networks (WPAN). • UWB (Multi-band OFDM). IEEE Wireless Local Area Networks (WLAN). Wireless Network. Design & Architecture. Matt Peterson. Bay Area Wireless Users Group. Rajendra Poudel. Nepal Wireless/ENRD.
Learn Wireless Basics
If you are building networks in the United States, you can only use channels 1 through In the rest of the world, channels 1 through 13 are generally usable, and in a few places channel 14 is available. Despite that, the best channels in the United States and most of the world to use for 2. This will minimize interference caused by partially overlapping Wi-Fi signals: You could use other sets of Wi-Fi channels, as long as they are 5 channels apart - for instance 3, 8 and This may not be optimal though, as channels 1 and 2 would be unused, and in many places in the world channel 13 is not available.
Wherever you are, try and check what channels are most in use, and plan your network to use a channel that doesn't overlap. This may not always be true -- more and more wireless equipment is starting to use the 5GHz In the United States, only channels available for building mesh networks are 36, 40, 44, 48, , , , , and The best place to check what is allowed in your area is online.
Links are provided in External Resources at the end of this document. When setting up your wireless network, you will need to think about what frequency band to use, and what channel to use.
Power and Receiver Sensitivity 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. A few examples of the transmit power levels in common Wi-Fi hardware is below: 10mW 10dBm : Laptop or smartphone, or very low cost Wi-Fi router.
About 25 to 50 meters mW 20dBm : Indoor home or office router. About 50 to meters mW 20dBm : Outdoor sector router.
How to Hack WiFi (Wireless) Network
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. Antennas 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. All stations are equipped with wireless network interface controllers WNICs.
Wireless stations fall into two categories: wireless access points , and clients. Access points APs , normally wireless routers , are base stations for the wireless network.
They transmit and receive radio frequencies for wireless enabled devices to communicate with. Wireless clients can be mobile devices such as laptops, personal digital assistants , IP phones and other smartphones , or non-portable devices such as desktop computers , printers, and workstations that are equipped with a wireless network interface.
An independent BSS IBSS is an ad hoc network that contains no access points, which means they cannot connect to any other basic service set. Access points in an ESS are connected by a distribution system. Distribution system[ edit ] A distribution system DS connects access points in an extended service set. The concept of a DS can be used to increase network coverage through roaming between cells.
DS can be wired or wireless. In ad hoc mode, mobile units transmit directly peer-to-peer. In infrastructure mode, mobile units communicate through an access point that serves as a bridge to other networks such as Internet or LAN. Since wireless communication uses a more open medium for communication in comparison to wired LANs, the Many access points will also offer Wi-Fi Protected Setup , a quick but now insecure method of joining a new device to an encrypted network.
Infrastructure[ edit ] Most Wi-Fi networks are deployed in infrastructure mode. In infrastructure mode, a base station acts as a wireless access point hub, and nodes communicate through the hub. The hub usually, but not always, has a wired or fiber network connection, and may have permanent wireless connections to other nodes.
Wireless access points are usually fixed, and provide service to their client nodes within range. Wireless clients, such as laptops, smartphones etc. Sometimes a network will have a multiple access points, with the same 'SSID' and security arrangement. In that case connecting to any access point on that network joins the client to the network. In that case, the client software will try to choose the access point to try to give the best service, such as the access point with the strongest signal.
There is no base and no one gives permission to talk. A WiFi Direct network is another type of network where stations communicate peer to peer.
In a Wi-Fi P2P group, the group owner operates as an access point and all other devices are clients. There are two main methods to establish a group owner in the Wi-Fi Direct group. In one approach, the user sets up a P2P group owner manually. In the second method, also called negotiation-based group creation, two devices compete based on the group owner intent value.
The device with higher intent value becomes a group owner and the second device becomes a client. A peer-to-peer network allows wireless devices to directly communicate with each other.
Wireless devices within range of each other can discover and communicate directly without involving central access points. This method is typically used by two computers so that they can connect to each other to form a network. This can basically occur in devices within a closed range. If a signal strength meter is used in this situation, it may not read the strength accurately and can be misleading, because it registers the strength of the strongest signal, which may be the closest computer.Backtrack comes with a number of security tools.
Notice that the frequency ranges used in CB radio, FM radio, and TV broadcasts are only a fraction of the entire spectrum. These are often long, rectangular antennas that are separate or integrated in to a router. In some cases, usually with more business or professional oriented equipment you can find the information for transmit power and receive sensitivity.
It is more effective compared to passive cracking. 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. An independent BSS IBSS is an ad hoc network that contains no access points, which means they cannot connect to any other basic service set.
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