WIRELESS NETWORK PDF
Wireless Networking. Technology. From Principles to Successful Implementation. Steve Rackley. AMSTERDAM • BOSTON • HEIDELBERG • LONDON. PDF | INTRODUCTION Wireless networks have been a crucial part of communication in the last few decades and a truly revolutionary. This module provides an introduction to wireless networks in general and wireless LANs in Learn architectural differences of various wireless networks.
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As a network administrator, architect, or security professional, you need to understand the capabilities, limitations, and risks associated with integrating wireless. ❑Wireless is convenient and less expensive. ❑Limitations and political and technical difficulties inhibit wireless technologies. ❑Lack of an industry-wide. Introduction. Wireless technology has helped to simplify networking by enabling multiple computer users to simultaneously share resources in a home or.
Radio and spread spectrum technologies — Wireless local area networks use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology.
Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. IEEE Free-space optical communication uses visible or invisible light for communications. In most cases, line-of-sight propagation is used, which limits the physical positioning of communicating devices. Types of wireless networks[ edit ] Wireless PAN[ edit ] Wireless personal area networks WPANs connect devices within a relatively small area, that is generally within a person's reach.
The use of spread-spectrum or OFDM technologies may allow users to move around within a local coverage area, and still remain connected to the network.
Products using the IEEE Fixed wireless technology implements point-to-point links between computers or networks at two distant locations, often using dedicated microwave or modulated laser light beams over line of sight paths. It is often used in cities to connect networks in two or more buildings without installing a wired link.
To connect to Wi-Fi , sometimes are used devices like a router or connecting HotSpot using mobile smartphones. Wireless ad hoc network[ edit ] A wireless ad hoc network, also known as a wireless mesh network or mobile ad hoc network MANET , is a wireless network made up of radio nodes organized in a mesh topology. Each node forwards messages on behalf of the other nodes and each node performs routing.
Ad hoc networks can "self-heal", automatically re-routing around a node that has lost power.
Various network layer protocols are needed to realize ad hoc mobile networks, such as Distance Sequenced Distance Vector routing, Associativity-Based Routing , Ad hoc on-demand Distance Vector routing , and Dynamic source routing. These networks can be used to connect branch offices of business or as a public Internet access system. The wireless connections between access points are usually point to point microwave links using parabolic dishes on the 2.
A typical system contains base station gateways, access points and wireless bridging relays. Other configurations are mesh systems where each access point acts as a relay also. When combined with renewable energy systems such as photovoltaic solar panels or wind systems they can be stand alone systems. In a cellular network, each cell characteristically uses a different set of radio frequencies from all their immediate neighbouring cells to avoid any interference.
When joined together these cells provide radio coverage over a wide geographic area. This enables a large number of portable transceivers e. Although originally intended for cell phones, with the development of smartphones , cellular telephone networks routinely carry data in addition to telephone conversations: Global System for Mobile Communications GSM : The GSM network is divided into three major systems: the switching system, the base station system, and the operation and support system.
Is bit WEP supported? Is there a roaming function? Software How do you update the firmware? Firmware is downloaded upon startup from the host or external Flash memory.
Downloading from the host will upgrade the firmware, while downloading from external Flash will require rewriting the contents of the Flash. Is the source code for device drivers provided? Linux device drivers include the source code. ROHM's module with attached antenna has already obtained Radio Law certification, eliminating the need for an external antenna. The telecommunications network at the physical layer also consists of many interconnected wireline network elements NEs.
These NEs can be stand-alone systems or products that are either supplied by a single manufacturer or are assembled by the service provider user or system integrator with parts from several different manufacturers.
Wireless NEs are the products and devices used by a wireless carrier to provide support for the backhaul network as well as a mobile switching center MSC. Reliable wireless service depends on the network elements at the physical layer to be protected against all operational environments and applications see GR, Generic Requirements for Network Elements Used in Wireless Networks — Physical Layer Criteria.
What are especially important are the NEs that are located on the cell tower to the base station BS cabinet. The attachment hardware and the positioning of the antenna and associated closures and cables are required to have adequate strength, robustness, corrosion resistance, and resistance against wind, storms, icing, and other weather conditions.
Requirements for individual components, such as hardware, cables, connectors, and closures, shall take into consideration the structure to which they are attached. Compared to wired systems, wireless networks are frequently subject to electromagnetic interference.
This can be caused by other networks or other types of equipment that generate radio waves that are within, or close, to the radio bands used for communication. Interference can degrade the signal or cause the system to fail.
Some materials cause absorption of electromagnetic waves, preventing it from reaching the receiver, in other cases, particularly with metallic or conductive materials reflection occurs.
This can cause dead zones where no reception is available. In multipath fading two or more different routes taken by the signal, due to reflections, can cause the signal to cancel out at certain locations, and to be stronger in other places upfade.
Chapter 2 Heterogeneous Wireless Networks
The hidden node problem occurs in some types of network when a node is visible from a wireless access point AP , but not from other nodes communicating with that AP. This leads to difficulties in media access control collisions.
The exposed terminal problem is when a node on one network is unable to send because of co-channel interference from a node that is on a different network. The wireless spectrum is a limited resource and shared by all nodes in the range of its transmitters.
Bandwidth allocation becomes complex with multiple participating users. Often users are not aware that advertised numbers e. With increasing demand, the capacity crunch is more and more likely to happen.
User-in-the-loop UIL may be an alternative solution to ever upgrading to newer technologies for over-provisioning. Shannon's theorem can describe the maximum data rate of any single wireless link, which relates to the bandwidth in hertz and to the noise on the channel.
One can greatly increase channel capacity by using MIMO techniques,    where multiple aerials or multiple frequencies can exploit multiple paths to the receiver to achieve much higher throughput — by a factor of the product of the frequency and aerial diversity at each end.
How to Hack WiFi (Wireless) Network
The total network bandwidth depends on how dispersive the medium is more dispersive medium generally has better total bandwidth because it minimises interference , how many frequencies are available, how noisy those frequencies are, how many aerials are used and whether a directional antenna is in use, whether nodes employ power control and so on. Cellular wireless networks generally have good capacity, due to their use of directional aerials, and their ability to reuse radio channels in non-adjacent cells.
Additionally, cells can be made very small using low power transmitters this is used in cities to give network capacity that scales linearly with population density. Wireless access points are also often close to humans, but the drop off in power over distance is fast, following the inverse-square law.
From Wikipedia, the free encyclopedia. Main article: Channel capacity in wireless communications.
See also: Wireless electronic devices and health. Retrieved 8 February Bluetooth To Mobile Phones". Archived from the original on 29 October Retrieved 8 July Retrieved 27 April GSM Association.
Archived from the original on 19 July Retrieved 16 March In both of these examples, there are just two wireless devices linked together - and the antennas determine the range at which they can connect.
Fixed wireless technology implements point-to-point links between computers or networks at two distant locations, often using dedicated microwave or modulated laser light beams over line of sight paths. Products using the IEEE WEP is based on passwords; this makes it vulnerable to dictionary attacks. A wireless network is a computer network that uses wireless data connections between network nodes.
Retrieved 8 February So a year sitting in a classroom near a wireless network is roughly equivalent to 20 minutes on a mobile. How to access a wireless network?
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