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4G Wireless network


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INTRODUCTION

Ever since the evolution of wireless communications networks, aspects like QoS (quality of service), data rate requirement, technology employed and connectivity across the globe, demands regular up gradation. The concept of 4G evolved mainly to overcome the shortcomings of 3G networks and to converge various coexisting networks, along with the wide variety of new services. In deployment of 4G systems user has been given at most importance to ensure a long lasting, sound and profitable future of 4G.
End to end IP and high quality streaming video will be amongst 4G’s distinguishing features. Wireless World Research Forum (WWRF) has defined 4G as a network that operates on internet technology and combines it with other applications and technologies such as Wi-Fi and Wi-Max at a speed of 100 Mbps (in cell phone networks) to 1 Gbps (in local Wi-Fi networks). International Telecommunications Union (ITU) states that future of wireless communication systems can be realized by fusion of existing, enhanced and newly developed elements of current 3G systems and other existing wireless systems with high commonality and seamless internetworking. ITU refers 4G as “beyond IMT-2000”. 4G will be a convergence platform working across various networks starting from Business Areanetwork (BAN), Personal Area Network (PAN), Local Area Network (LAN), Metropolitan Area Network (MAN) and cellular networks.

Thus 4G will be integrating heterogeneous networks serving heterogeneous terminals and supporting heterogeneous services, but appearing to the user as a simple and single homogeneous network.

HISTORY

4G has evolved as a result of constant up gradation and finally convergence of various generations right from starting of first generation (1G), second generation (2G), two point five(2.5G) and third generation (3G) mobile communication networks.

FIRST GENERATION (1G)
First generation cellular networks were developed in early 1970’s, mainly meant for telephony service. Thus voice was the main traffic operating at a frequency of 800MHz extending up to 900MHz cellular bands. The multiplexing technique employed was Frequency Division Multiple Access (FDMA). Main standards employed in 1G were Advanced Mobile Phone System (AMPS) and Nordic Mobile Telephone (NMT). The capacity of 1G networks were naturally small because authentic 1G networks were not cellular.

SECOND GENERATION (2G)

Evolved in 1980’s second generation (2G) cellular networks were mainly commercially centric. It provided the platform for earliest digital telecommunication. They were designed to offer service of digital voice with a limited capability of low data rates thus giving new service of Short Message Service (SMS).Multiplexing techniques used were Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA).
Main second generation standards was Global System for Mobile Communication (GSM). GSM attained the status of one of the most popular standard, globally.

TWO POINT FIVE
GENERATION (2.5G)

2.5G category of public mobile network was mainly meant for improved data rates, adding services such as General Packet Radio Service (GPRS) to a 2G network in the year 1985.Thus the services of 2G network were modified to high capacity packetized data. Other 2.5G solutions include High Speed Circuit Switched Data (HSCSD) and Enhanced Data Rates for Global Evolution (EDGE). Main features of GPRS employed were packet based transmission and improved data rates with applications such as e-mail and internet browsing in addition to the messaging service.

4G Wireless Networks

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What is 4G?

4G is the fourth generation wireless network communications technology Standard. When implemented, users of 4G devices will have the ability to access to application ranging from basic voice communication to seamless real time streaming video.

What technologies comprise 4G?

Unlike previous standards such as 3G (third generation), 4G is based entirely on packet switched networks. In addition, all 4G networks will be digital and will provide higher bandwidths of up to 100 Mbps. 4G is actually a collection of previous standards as oppose to an entirely new standards. Standards such as 3G and Bluetooth will be incorporated in to the 4G standards.

Why do we need 4G?

One may wonder why 4G is needed when 3G has not yet been fully implemented. Firstly 3G’s maximum data transfer rate of 384 Kbps is much lower than 2 Mbps. The most influential reason for the fall of the 3G networks and rise of 4G networks is the cost related to the creation of 3G networks. In Europe and Asia, several companies have invested huge money on licensing and implementation of 3G Networks.
With its use of existing technologies and communication standards, 4G present a comparably inexpensive standard. 4G will utilize most of the existing wireless communication infrastructure. In addition, there will be less licensing costs in comparison to 3G since 4G will utilize frequencies deemed to be in the public domain.

What are the specifications of 4G?

One may ask how 4G can provide a 10 times increase in data transfer over 3G. This speed can be achieved through Orthogonal Frequency Division Multiplexing (OFDM). OFDM can not only transfer data at speed of more than 100 Mbps, but it can also eliminate interference that impairs high speed signals.

What are the potential applications of 4G?

With its high bandwidth and incorporation of several standards, 4G will provide for a vast number of presently non-existent applications for mobile devices. Some believe that it will be possible for users to purchase groceries, watch movies, and open their garages all with one single mobile device. Experts have stated that 4G devices will differ from present day mobile devices in that there will be fewer navigation menus. [4] Instead the devices will interpret the environment of the device and base actions on the users input. In addition, 4G
will likely succeed where 3G failed and provide a seamless network for users who travel and require uninterrupted voice/data connections.

Applications

Wireless users can be categorized into generalized segments. Users can be segmented in many ways. We are considering segmenting users in to the following categories: Gender, age, Internet usage, income brackets and mobile professional.
The Gender segment refers to new female users, versus traditional male users. These users are typically medium-income individuals. The types of applications being developed for this segment are social and entertainment applications such as instant Messaging and chatting. Being developed for this segment are messaging applications such as mobile faxing, e-mailing, and instant messaging? To augment solid applications, providers are also developing subscriber equipment to allow for roaming on disparate, worldwide
The Age segment is composed of the youth market—generally individuals 18 years old or younger. Typically these users do not pay for their own service—their parents or guardians do. The types of applications being developed for this segment are social and entertainment applications such as music services.

Orthogonal Frequency Division Multiplexing

OFDM is a communications technique that divides a communications channel into a number of equally spaced frequency tones (bands). OFDM is a form of multi-carrier modulation (MCM) where a sub-carrier within each frequency band is modulated to carry a portion of the user information. A communications data stream is effectively split into N parallel low bandwidth modulated data streams (Figure 1). Each sub-carrier overlaps, but they are all orthogonal to each other, such that they do not interfere with one another.

4G Network Architecture

The number of access networks in public, private business and home areas is increasing. To save both users and services from having to deal with many different access technologies, authentication strategies, and network peculiarities, these details should be hidden from them. On the other hand, the characteristics of the particular access network being used do matter. End users for example want to be able to use a specific network based on certain selection criteria like speed and cost. Service providers will need access to specific network characteristics to be able to enhance their services, and may have certain requirements such as minimum delay guarantees. For the end user this means that in most circumstances he will not be aware of his services using different access networks simultaneously. This involves concepts like seamless roaming and the Virtual Home Environment (VHE). Another aspect is that the user needs to control the usage of the available networks, especially when this usage comes with a price. This involves a (potentially complex) decision making process which may be guided by policy management tools, with support from both end user devices and the networks. Another kind of integration is that of public, private and home networks. This has not received much attention yet, at least not to the extent as expected to be needed for next generation networks.

Business model of 4G Network

The current model assumes there are relationships between the end user, the service provider, and the network operator. In the 4G worlds, the number of access networks and therefore the number of network operators will increase rapidly. Especially the construction of many so-called “hotspots”, urban areas with Wireless LAN coverage, will cause this. Both the end user and the service provider do not want to be bothered with the peculiarities of these networks, i.e. end users still want to use the services offered by service providers irrespective of the network they are connected to. This asks for a service centric approach where the end user, the service provider and network operator are loosely coupled through a Service Support role,
Two main responsibilities of Service Support are service aggregation and network integration Service aggregation (SA) enables ubiquitous service provisioning to end users, whereas network integration (NI) ensures that this can be realized regardless of the network the end user is connected to. The end user benefits from being able to access his/her subscribed services anywhere and anytime.

End users Identities and services

Third party service providers provide end user services. These service providers have established a legal relationship or Service Level Agreement (SLA) with one or more service aggregators. The services can benefit not only from a large customer base, but could also adapt their services and applications based on information from the network provided via the aggregators. It is envisaged that the user’s location can be obtained from the network integrator (and therefore from access network) to deploy location-based services. The concept of user identity plays an important role in integrated service delivery. This ranges from authentication and access control to services, to accounting and billing; to be able to charge the correct end user for using his value-added context-based services.