USE OF WIRELESS TECHNOLOGIES IN COMPUTER SYSTEMS
AIM: This paper is aimed to evaluate different types of wireless technologies and its uses in computer systems.
Wireless technology is a fastest growing section of the communication industry. In which this systems have experienced an enormous growth over the last decade and currently contains around two billion users worldwide. Wireless networks have many advantages like which they are flexible, faster and very easy to use and maintain. In most developed countries wireless technologies became a business tool. Many new applications are taking part in this area to concrete systems, but several technical issues remain in different standards of the technology that delivers the performance necessary to support increasing applications. In this version we will briefly review the history of wireless technology i.e. Overview of wireless LAN Technologies, how it works, and we describe the different type of wireless networks and different standards and their specifications.
The first wireless communication is done by using smoke signals, torch signalising, flashing mirrors in which these systems only transform information over very short distances. and then these are replaced by the telegraph network and later by a telephone. After a few decades the first radio transmission was demonstrated by Heinrich Rudolf herz. Where these radio waves are transmitted through a small extent using analog signals and then Marconi extended this radius of radio waves to transmit to a much more large extent than before.
Nowadays the radio system transmits digital signals which are composed of binary bits. These bits are grouped into packets and this is called a packet radio and entitled as Alohanet. Alohanet used network architecture of star topology. And these are known as first wireless local area networks (WLAN) which enabled data access like email, transferring of files. But due to low speed data rates and high costs, security problems this are not most successful which leaded to the second type of WLAN released which is 4 times faster than the before systems. These systems are using IEEE 802.11 standards which have better performance, and became the preferred internet access.
Regarding all these factors the most successful segment in this wireless communication is cellular phones. Though in the first generation of cellular systems have low speeds which supported only few users, second generation cellular systems provides mainly voice services with a high speed data services like sms, email, internet access. But the second generation cellular systems support different standards in different cities which did not supported the roaming facility. And these leaded to third generation cellular system which supports multimode and standards like nationwide and worldwide roaming.
HISTORY OF FIRST GENERATION SYSTEMS:
Mobile communications are started in the late 1970s, with the execution of an experiment system in Chicago in 1978, where this system is known as advanced mobile phone service (AMPS) which operates with 800 MHz band. Meanwhile the commercial AMPS were launched in Japan. During these years the first European system was launched in Sweden with the technology known as Nordic mobile telephony (NMT) which operates with 450-MHz and the update version of this is 900 MH-z.and after this British introduced the technology known as total access communication systems (TACS).the weakness of first generation technologies is limited capacity, fraud this problems lead to second generation systems.
HISTORY OF SECOND GENERATION SYSTEMS:
Second generation systems are digital which have many advantages like improved capacity, security, and many sophisticated services. Technologies involved in second generation systems are interim standard 136(IS-136) TDMA, IS-95 CDMA and global system for mobile communication (GSM).Though this system offers successful results, they are not well appropriate for data communications.
HISTORY OF THIRD GENERATION SYSTEMS:
Third generation systems are mainly designed for communicating in new ways like E-mail, instant messaging, the world wide web, and the mobility, for this ways international telecommunication union (ITU) worked in several ways which is known as future public land and mobile telecommunication (FPLMTS) and again it was renamed as international mobile telecommunication-2000(IMT-2000).
KEY CHARACTERSTICS/ OBJECTIVES:
- Providing an overview of the past and current wifi standards.
- Identifying different types of wireless systems and their uses.
- To analyse different research papers from the chosen bibliography that helps in increasing performance impacts.
- To discuss the issues that helps in increasing the efficiency of the current systems.
CRITICAL LITERATURE REVIEW:
A rapidly changing technology creates new trends in various applications. The use of wireless technologies in the computer makes the mode of communication more efficient and comfortable. There are many works carried on wireless networks in recent times with its vastness and its potential use in the daily life. The effort of Changsu Suh , Zeeshan Hameed Mir , Young-Bae Ko on their work "Design and implementation of enhanced IEEE 802.15.4 for supporting multimedia service in Wireless Sensor Networks" assisted a great deal with creative innovation.
TYPES OF WIRELESS NETWORKS:
The three different types of wireless networks are
- Wide area networks(WANs)
- Wireless local area networks(WLANs)
- Personal area Networks
WIDE AREA NETWORKS:
WANs is a telecommunication network generally used for connecting computers in one location to communicate with the users of another location , this are regularly used by the business organizations, industries to exchange the data.WANs are quite related to WLANs but they are controlled and operated differently which covers a large physical area and it can transfer data at the rate of 625 mbps or more .WANs are used to connect LANs where at each end of the line router is connected and a modem on the other.WANS are also built using circuit switching and packet switching methods, and different protocols like TCP/IP,SONET/SDH,X2.5 etc.out of all these X2.5 protocol is mostly used for WANs in nowadays. In packet switching users share general carrier resources and networks are connected to carrier networks so that the users can share the data, the whole section where the carrier network is shared is called cloud. Examples of packet switching are Asynchronous Transfer Mode (ATM), frame relay and X.25.
In circuit switching data connections is done whenever it is needed and it can be terminated whenever the data processing is complete such as like voice message in normal telephone line. Example for the circuit switching is ISDN (Integrated Services Digital Network).
PERSONAL AREA NETWORKS:
This technology allows user to set up wireless communication devices like mobile phones, and computers that are operated in shorter range. Many wireless networking standards are mainly focused on connecting devices to each other in a larger distance like pc to pc. Many applications have far less stringent range requirements, such as connecting peripherals wirelessly to a mobile device or adding components to a home theater system[ ],for such type of systems PANs is well supported. It ranges signal up to 1 to 100m, devices which we can equip with PANs are mobiles which are compatible with the Bluetooth.
This new standard (802.15.1) which is derived from IEEE generally known as Bluetooth. This works with low data rate and less wireless networking.many standards are developed for WPANs such like 802.15.1 for cable rapalcement technology,802.15.3 is for high rate applications(HR-WPAN),it provides a very low cost and consumes less power.it supports 11 mbps speed data rate with a range of 10meters.802.15.4 is for low rate applications(LR-WPAN),it consumes less power and small band width and work for large wireless networks. all of these standards are operated at the same frequency band 2.4GHz and addressed by IEEE.
WIRELESS LAN TECHNOLOGIES:
WLANs are having quality in network areas because this technology is easy very easy to use and implement. The increased demand for the wireless systems leads the development from wired LANS to wireless LANs (WLANs).this system is based upon the cellular architecture which is controlled by a base station. Other Wireless LAN standards that are now being investigated in the level of wireless technology are HiperLAN, HomeRF SWAP, IEEE 802.11, blue tooth. Among all of this IEEE 802.11 is preferred standard which mainly supports wireless LANs.
CLASSFICATION OF WIRELESS LANs:
Wireless LANs can be classified into two segments i.e.adhoc wireless LANs and wireless LANs with infrastructure .in this adhoc networks are designed such that wireless nodes join together to establish point-to-point communication. Here a user can communicate straightly with other users within the network such that it enables to communicate only within the transmission range. Whereas in wireless LANs with infrastructure there is a high speed wired which acts as an access point for the wireless nodes in order to communicate. But in order to communicate data a relation must be established between user and access points, then only it can exchange data. Some of the key challenges in the implementation of wireless LANs are [ ]
- Multipath transmission
- Network security
- Connection problems
- Low power design
- Radio signal interference
The two different types of standards are based on official and public, where official standard operated by official organization, such as IEEE.this is usually supported by government. In the case of public standard it is supported by private organizations, such as TCP/IP.
IEEE (Institute for Electrical and Electronic Engineers) is the standard technology of wireless LANs which specify 2.4GHz operating frequency with data rates of 1mbps and 2 mbps. IEEE 802.11 introduced two supplements 802.11a, 802.11b where 802.11b is the is the most used version in the wireless LANs, and 802.11a standard uses a high speed data rates like 54mbps.
802.11 networks are designed such that it works without any failures; there is an alternative for putting into action of three types of WLAN topologies [ ].
- Independent basic service sets(IBSSs)
- Basic service sets(BSSs)
- Extended service sets(ESSs)
IBSS: In this service it contains a group of stations which transfers data from one to station to another. Since it a point to point connection and small size it is usually referred as an adhoc network and it is created when the user form a self contained network without the use of access point.
BSS: BSS is a set of 802.11 stations where the users communicate with one another through the access point which act as hub for all the stations. So it doesn't allow the user to communicate directly to another user. Here there is no restriction for distance between access point and station.
ESS: The collection of BSSs interconnected via the distributed systems is known as Extended service sets [ ].it contains multiple number of access points, which are connected without a wired connection, and so it acts as a wireless. This service makes the network to provide in larger areas.
This is developed by the Institute of Electrical and Electronics Engineer(IEEE) which can operate at 300MHz of band width and also known as Wi-Fi5. It has good scalability, high speed up to 54Mbps and allows multi users. 802.11a uses Orthogonal Frequency Division Multiplexing (OFDM), a new encoding scheme that offers benefits over spread spectrum in channel availability and data rate [ ], and this uses eight non overlapping 20MHz channels. High Data rate is available by combining all low speed sub carriers so that it creates one high speed channel. Due to the different modulation techniques used in the 802.11a the speed of data rate changes.
ADVANTAGES OF 802.11 STANDARDS:
- It has an ability to work with the multiple appliances and the chosen wireless network type.
- It is an improved standard in which users can easily employ wireless devices; this makes product development very fast.
- It has a very low cost as more users comply with this standard.
- It has a high speed data rate.
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