Abstract
Content
- Introduction
- 1. Relevance of the topic
- 2. The purpose and objectives of the study, the planned results
- 3. Wireless Overview
- 3.1. Wireless networks: classification, organization, principle of operation
- 3.2. Wireless computer networks: classification and operation
- 3.3. Wireless Networking
- 3.4. Advantages and disadvantages of wireless networks
- Conclusion
- References
Introduction
Wireless local area networks are becoming increasingly popular, more and more homes, office buildings, cafes, libraries, air terminals, metro stations and other public places are equipped with the appropriate equipment to connect computers and smartphones to the Internet. In a wireless network, two or more neighboring computers can exchange data without an Internet connection. The main wireless LAN standard is 802.11. [1]
1. Relevance of the topic
In the 80s of the last century, the GSM digital data transmission standard appeared. On which almost all mobile operators are still working. This can be considered the starting point for the development of wireless network technologies. This protocol was rapidly improving, and in 1997, a new technology for the exchange of information at a distance appeared without the need for wires. This technology is called IEEE 802.11, which is better known to a wide range of people like WiFi.
Since the advent of the first version of 802.11a in the 90s of the last century, not much time has passed, more advanced technologies have appeared, the speed and quality of data movement has increased. Almost all buildings, offices and industrial enterprises are shrouded in wireless networks. The transition to a newer specification 802.16, called WiMax, is expected. This technology allows to significantly expand the range of connection from several tens of meters via WiFi, to tens of kilometers without loss of quality and speed. Of course, this technology will be expensive at the beginning, but over time, all mobile devices are planned to be equipped with a WiMax radio module.
2. The purpose and objectives of the study, the planned results
The aim of the work is to improve the quality of service of a wireless LAN using IEEE 802.11 technology.
The main objectives of the study:
- Analysis of wireless networks, in particular IEEE 802.11 technology;
- Study of the problems of modern wireless LAN;
- Study of QoS requirements for wireless networks;
- Development of a mathematical model of the network;
- Building a network model in which the quality of customer service is improved.
Object of study: wireless infocommunication network.
Subject of research: the processes of propagation of radio signals in wireless information and communication networks.
3. Wireless Overview
3.1. Wireless networks: classification, organization, principle of operation
It is difficult to imagine the life of a modern person without the Internet. View mail, business and personal correspondence, reading news, watching movies and TV shows, it became possible with the advent of computer networks. And with the advent of mobile devices, such as smartphones, tablets, laptops, it became possible to exchange information almost anywhere a person was. This became possible with the advent of wireless LAN and WAN.
3.2. Wireless computer networks: classification and operation
In the general case, a wireless computer system is designed to ensure the interaction of users, various servers and databases through the exchange of digital signals via radio waves. A connection can be made in several ways: Bluetooth, WiFi or WiMax. Classification of wired and wireless networks is carried out on the same grounds:
- Personal computer network (PAN - Personal Area Network). The connection is made, for example, between mobile phones that are in close proximity to each other.
- Local area network (LAN - Local Area Network). Connection within one building, office or apartment.
- City computer network (MAN - Metropolian Area Network). Work within the same city.
- Global Computer Network (WAN - Wide Area Network). Global Internet access.
The 802.11 specification is a set of protocols that fully comply with accepted standards of open networks of the OSI model (Open System Interconnection). This reference model describes the seven levels of data exchange, but the 802.11 protocol differs from the wired one, only on the physical, and, partly, on the data link layer. These are the levels of direct communication. The physical transmission layer is radio waves, and the link layer controls access and provides data exchange between two devices.
Figure 1 - Classification of wireless networks
Wi-Fi works on two frequency bands: 2.4 (802.11a / b / g / n standards) or 5 (802.11n only) GHz. The radius of action can reach 250-300 meters within the line of sight and up to 40-50 meters in enclosed spaces. Each specific equipment provides different physical indicators depending on the model and manufacturer.
The data transfer rate varies depending on the standard used and can range from 11 Mbps with the 802.11b standard to 600 Mbps at 801.11n.
3.3. Wireless Networking
WiFi can be used for several purposes:
- organization of the corporate network of the enterprise;
- organization of a remote workplace;
- providing access to the Internet.
Connection is carried out in two main ways:
- Work in infrastructure mode (Infrastructure Mode), when all computers communicate with each other through an access point (Access Point). The router works in the switch mode, and very often has a wired connection and Internet access. To connect you need to know the identifier (SSID). This is the most common type of connection for the average person. This is true for small offices or apartments. In the role of access points are the router (Router).
- The second connection option is used if you need to connect the two devices directly to each other. For example, two mobile phones or laptops. This mode is called Adhoc, or equal to equal (peer to peer).
Household routers make it possible to connect not only via Wi-Fi. Almost everyone is equipped with several Ethernet ports, which makes it possible to bring into the network gadgets that are not equipped with a WiFi module. In this case, the router enters as a bridge. Allows you to combine wired and wireless devices.
To increase the range of a network or to expand an existing topology, access points are pooled in Adhoc mode, while others connect to the network through a router or switch. It is possible to increase the coverage area by installing additional access points as a repeater (repeater). The repeater picks up the signal from the base station and allows customers to connect to it.
In almost any public place, you can catch a WiFi signal and connect to access the Internet. Such public access points are called Hotspot. Public areas with Wi-Fi coverage are found in cafes, restaurants, airports, offices, schools and other places. This is a very popular direction at the moment.
3.4. Advantages and disadvantages of wireless networks
The main advantage of the transmission of information through the air, derives from the very name of the technology. There is no need to lay a huge number of additional wires. This significantly reduces networking time and installation costs. To use Wi-Fi networks, there is no need to purchase a special license, so you can be sure that a device that complies with the 802.11 standard, purchased at one point on the globe, will work in any other.
Wireless networks are well upgraded and scaled. If it is necessary to increase the network coverage, only one or several additional routers are installed without the need to change the entire system. In areas with uneven coverage, the client device will always switch to the point that has the highest quality of communication.
Among the shortcomings worth noting security problems. All modern routers support several encryption protocols, it is possible to filter clients by MAC address. Thus, with sufficient care, you can organize a system that is least exposed to risks. Another drawback is the overlap of coverage areas from different routers. In most cases, this problem is solved by switching work on another channel. [2]
Conclusion
In this paper, we reviewed the wireless technologies, in particular IEEE 802.11 Wi-Fi. The relevance of this technology in modern information and communication networks is shown. Recommendations on building a wireless network were also proposed.
Note
The abstract is an overview and is not a complete version of the master's work. When writing this abstract the master's work is not completed yet. Planned completion date: June 2019. Extended information on the work and the full list of materials can be obtained from the author or his manager after the specified date.
References
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