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4G refers to the Fourth Generation of cellular wireless standards in telecommunications that will succeed it predecessors 3G 2G. It is a high-speed broadband wireless network that offered comprehensive & secure all IP based services. According to the ITU, requirements for 4G standards were specified by IMT-Advanced (International Mobile Telecommunication-Advanced). The data rates of 4G service for high mobility communication was set to 100 Mbps and low mobility communication was set to 1 Gbps.
It focuses on cellular system with extremely high data rates & the concept of seamless technology in all wireless systems. Carriers that are using OFDM (Orthogonal Frequency-Division Multiplexing) as an alternative to TDMA and CDMA are promoting their services as 4G even though their data rates are not high according to the ITU.
4G outdoor users that have Internet access through cell phones or smart phones were promised to have a targeted data speed of around 100 Mbps by the IMT-Advanced and the data speed for indoor users such as LAN (Local Area Network) was suppose to be around 1Gbps. This type of higher speed for both fixed and mobile Internet users is truly amazing. 4G proposes scalable channel bandwidth flexibility of up to 40 MHz. The network resources are dynamically utilized & shared to sustain more simultaneous users over each call. 4G also has the ability to propose high QoS (Quality of Service) for multimedia support and offer smooth handover heterogeneous networks. It must also have the ability to offer wireless LAN roaming & interact with systems used for video broadcasting.
Figure 5: Seamless Connection of Networks in 4G .
The 4G architecture comprises of 3 crucial areas of connectivity namely
- PAN (Personal Area Network)
- WAN (Wide Area Network
- Cellular Connectivity
Each device will have the ability to interact with the Internet based information that is modified over the network used by the device at that time. This structure can support a wide range of 4G mobile devices that sustain global roaming.
In 4G networks users that join the network have the ability to add mobile routers to the infrastructure. Changing user patterns can be accommodated by dynamically shifting network capacity & coverage. Creating additional routes as the concentration of people is higher in one area compared to the other enables additional access to the capacity of the network. Users can easily avoid congested routes by hoping to the less congested routes. This allows the network to automatically balance the capacity by increasing the network utilization. The service for all the users improve with the increase in number of users.
Need for 4G
One of the questions that come to mind when thinking about future 4G systems is there need. The first application to be mobilized was voice telephony, few years ago. The short message service (SMS) was the first application to be introduced as a mass-market application. The hardware complexity was not an issue at the given time along with the advantage of small bandwidth requirements. The SMS was just the commencement of various data services like mobile email, web browsing etc. The key feature in most of them was the packet based wireless networks carrying IP data in one hand and powerful terminals that could cope with these applications on the other. Although the network capacity is still not an issue due to less number of users, there are number of reasons for increased bandwidth requirements in the future. First, the number of wireless users increases exponentially resulting into an increase in bandwidth requirement. Second, the popularity of video and music downloads has increased immensely within few years. The information content in a video or music is more than the corresponding text but so is the capacity requirement. Last but not the least, mobile social networks have taken the current internet usage to a much higher level. Picture viewing sites, web blogs and also video sharing sites have reshaped the internet.
The need for 4G arises from insufficient performances by 3G to meet the future needs & several incompatible standards. The requirement for service portability, universal mobility & the need for hybrid networks including both WLAN & cellular network design led to the invention of 4G. New modulation methods that offered higher bandwidth with the help of an all IP based network with converged data & voice capability were possible only by 4G. The chief characteristic developed by 4G was to offer accommodation for the QoS services that were set as requirements by the ITU.
4G technology guarantees secure, comprehensive & invulnerable IP based mobile service solutions for wireless modems, laptops, smartphones & other mobile devices. Applications such as Multimedia Messaging Service (MMS), mobile TV, wireless broadband access, video chat, and Digital Video Broadcasting (DVB) are being urbanized to use a 4G network. Other IP based services include enhanced gaming, high quality multimedia streaming, IP telephony & really fast broadband Internet can be accessed. This groundbreaking technology will have many more facilities available to users all around the world. Imagine having the ability to access information and services anytime, anywhere with a seamless connection as well as receiving large quantity of information, pictures, data & video are the key aspects of 4G technology.
The future 4G networks would consists of a set of numerous networks having IP based services as their common protocol such that the users are in control & can choose each application and environment. The chief achievement would be integrating 4G technology with the existing cellular technologies with the help of advanced technologies. The main features of 4G services that interest the users specifically are high dynamic integration & application adaptability. This means services are delivered & available to the users as per their preference & user’s traffic, radio environment & air interfaces are all supported by 4G.
Over the years researchers have been working on ways of fulfilling the above needs. Ethernet, Wireless LAN and TD-CDMA, were all supported by the developed network overall. The mobile technology of 4G should be focusing on the data-rate increase, new air-interface. The so-called core of the technology, OWA platform should also be embedded with high-speed wireless systems and wireless mobile system.
It should also,
- Reuse many different access technologies as possible thereby implementing various functions using the IP-based protocols and technologies.
- Provide real-time services with high enough quality like the current cellular networks.
- Accessibility to services that should not be affected by the handover interruption.
Mobile systems should have interfaces from various technologies simultaneously specially to TDCDMA (UMTS-TDD), wireless LANs (802.11b), and fixed networks (Ethernet).
Be capable of accessing to routers and provide an interface between a wired network domain and wireless. A single access router directly mapped to a single cell controls an IP subnet.
Provide a network management server for mobility management, charging, Quality of Service, security and paging issues in a fixed network.
Features of 4G
Features of 4G Wireless Systems:
User Personalization and Friendliness: The combination of personalization and friendliness is a key feature in 4G. The well-designed transparency allows man and the machine to interact naturally and is well appreciated. The operator can send the data to the user depending on his/her preference or the data can even be filtered at the user end based on his/her requirement. In order to address a mass market and gain a positive impact on people’s lifestyle it should be kept in mind that every user wants to feel unique and important. Thus personalization enables the user to configure his device and select the services according to his preferences. The combination hence confers the right value to the user’s expense.
Heterogeneity: 4G should have a definite advantage in the user’s day-to-day life. This is obtained by combining the network and terminology heterogeneity, both of which contribute equally to the efficiency of usage. With network heterogeneity, omni-directional connection and common service can be obtained thereby assuring certain level of quality of service. Heterogeneity enables a user to access and perform multiple things simultaneously for example, if a user wants to buy tickets to a museum and listen to music, he can do that. Terminals in 4G may have to some common services out of their capabilities due to which tailoring of the content might become necessary.
Since it is based on IP wireless connectivity, the optimization of internet is maximized. The circuit switching technology is replaced by packet switching. The specificity of an IP, thus increase the speed along with the reliability of transfer of data. The bandwidth is around 100Mhz and speed of data transmission up to 1 Gbps.
Support: It supports multimedia, voice, video, wireless internet and other broadband services.
Cost Effective: Transmission costs of various multimedia services are very low. High capacity, high speed and low cost per bit. Cost of leased spectrum figures in greatly in reaching profitability. For example, the initial resistance from the investment society is a hindrance for WiMAX. This in turn pushes the operators to create new ways of increasing capital.
Global mobility, service portability and scalable mobile networks.
Seamless switching or usually referred as handover is gaining popularity. Availability of inter- and intra- technology handovers promises minimum or no interruption thereby assuring Quality of Service (QoS). This is achieved with the help of continuous transparent maintenance of services and inclusion of WiFi to OFDMA.
Better scheduling and call admission control techniques are available.
Ad hoc networks and multi-hop networks: the independency from routers and access points is an added advantage. The dynamic activation of sender and receiver nodes is similar to a real-time system that is definitely a plus point of 4G. Also the network topology comes into play where every node is contributing to the data transmission.
Mobility of users across multiple terminals and terminals across multiple technologies.
Confidentiality of both user traffic and the network control information. 4G uses the IPV6 address scheme resulting in every cell having its own IP address. Interlayer security is provided in which only one layer is configured to do encryption on data.
Predecessors of 4G
LTE – Long Term Evolution
LTE (Long Term Evolution) is yet another technology under the brand of 4G technology. LTE is capable of giving a full support to the spectrum bands. Upgrading the current 3G networks to WiMAX is difficult in comparison to LTE. The pre 4G technology is known as 3GPP Long Term Evolution. If a 20 MHz channel is used LTE has a capacity of up to 50 Mbps in the uplink & 100 Mbps in the downlink.
WiMAX- Worldwide interoperability for Microwave Access
WiMAX or Worldwide Interoperability for Microwave Access, is a faster Wi-Fi
listed under 4G. Mobile operators using the latest spectrum bands benefits most
from the WiMAX. If a 20 MHz channel is used WiMAX would offer data rates
up to 56 Mbps in uplink & 128 Mbps downlink.
UMB – Ultra Mobile Broadband
UMB (Ultra Mobile Broadband) is based on TCP/IP networking technologies
cascaded over next generation radio system with data rates up to 280 Mbps.
The system was intended to be more proficient & powerful of supplying more
services than the technologies it was suppose to replace. UMB was the
name within 3GPP2 standardization group to improve the mobile standards
for next generation applications & requirements. Qualcomm is UMB’s lead
sponsor ended the development of this technology supporting LTE instead. It
intended to achieve data rates over 275 Mbps downstream & over 75 Mbps
Flash – OFDM
At an initial stage Flash-OFDM (Orthogonal Frequency Division Multiplexing) was supposed to be integrated into a 4G standard.
1G wireless telecommunications led to the invention of the first kind of wireless cellular architecture that is still being offered by most cellular network providers. 2G could support more users in a cell than 1G by using digital technology. This technology gave access to many more callers by making use of the same multiplexed channel. It was primarily used for voice communication & also included some very limited low rate data features such as SMS (Short Messaging Service). 2.5G gave access to the carriers to increase the data rates with just software upgrades with just making the users buy new handsets. 3G promised its users to offer greater bandwidth & higher data rates that grants permission to send as well as receive more information.
All 3 generations still have the Cellular Architecture or Star Topology where users within that cell can access a common central BTS (Base Transceivers Stations). The major advantage is that with this architecture carriers are able to construct nationwide networks, which most of the major carriers have already done. The major disadvantages of these networks as we progress are that as the data rate increases the output power increases so the size of the cell needs to be decreased in order to accommodate higher data rates. We would observe smaller cells as the consumers got scared with the increase in the output power. Some of the other disadvantages include no load balancing, singular failure point and spectral inefficiencies.
The two very important characteristics of 4G technologies are:
- End-to-End Internet Protocol
- Peer-to-Peer Networking
An all IP network would allow the users to use the same data applications that they use in wired networks. In peer-to-peer networking each device acts as a transceiver and a router for all the other devices in the network. This architecture eliminates the failure of single node.
4G is referred to as an ad hoc wireless networking technology, a combination of above characteristics. 4G plays a significant role by allowing users that are joining the network, the approach to add mobile routers to the existing infrastructure.
The usage patterns for consumers dynamically shifts the coverage & network capacity to be accommodate the changes as the users carry most of the networks with them. The users congregate leading to high demands of usage that also enables access to the network capacity as they create additional routes for each other. They tend to automatically skip from congested routes to lesser-congested routes. This authorizes the network to automatically balance capacity leading to an increase in network utilization. The user device that operate as router are basically a part of the infrastructure. So instead of carriers reducing the cost of devices they actually minimized and deployed the network of the carrier.
4G Mobile Network Architecture
Each user interprets 4G mobile communications differently. For some its purely provides higher data rates to radio interfaces but for other it is internetworking of wireless LAN and cellular technologies. In order to accommodate traffic demand foreseen in an economically feasible way , 4G mobile networks must accomplish manifold increase in capacity in comparison to its forerunner. Mobile networks are planned for circuit switched voice until now. Fourth Generation wireless architecture was planned as heterogeneous infrastructure consisting of distinctive access systems in a corresponding manner. The user supporting personal agents enjoys unrestricted and ubiquitous connectivity to various applications over the available network. The figure below illustrates potential 4G mobile network architecture including cellular, satellite radio, ad-hoc and hot spot components.
A BSC (Base Station Controller) accumulates calls from various base stations, enables handoffs, allot radio channels between BS (Base Station) and hands over calls to a more central mobile switching center. The emerging data networks overlie the existing voice architecture. With the increase in the data traffic this architecture has turned out to be cumbersome & difficult to be managed with several network entities.
The architecture contains common core Network connected to different wireless and wired networks. It is then connected to PSTN (Public Switched Telephone Network)/ISDN (Integrated Services Digital Network) via GGSN (Gateway GPRS Support Node). GGSN is the chief component of the GPRS (General Packet Radio Service) network. The GGSN is accountable for internetworking between packet switched networks and GPRS network such as Internet.
This architecture is associated to 2G via SGSN(Serving GPRA Support Node) from BSC. SGSN is accountable for distribution of data packets to and from mobile stations within its physical service area. Wireless communication is facilitated between UE (User Equipment) and the network by a piece of equipment known as BTS (Base Transreceiver Station).
The connection to 3G is through SGSN towards Node B via RNC (Radio Network Controllers). In 2G networks, Node B is equivalent to BTS. RNC replaces BSC and connects to various networks such as Ad-hoc mobile networks and WLAN access networks. Signaling protocols like SIP (Session Initiation Protocol) are extensively used for setting and tearing multimedia communication sessions like video and voice calls above the Internet.
The future of mobile communication networks will face challenges in incorporating and integrating various wireless technologies and mobile architectures to achieve flawless wireless infrastructure. Networking technology, has accepted that wireless or wired networks can interface with the core over the IP protocol.
IPv6 4G Network Architecture
The 4G architecture that supports flawless mobility between distinctive access technologies has an IPv6 based network architecture. Handovers between inter-technology need to be supported else mobility issues will arise. IP network architecture eliminates the voice-centric structure from the network. Instead of packet data overlaying on voice network separate, rather simple data architecture can be implemented which eliminates multiple elements from the network. BSC functions are equally distributed among media gateway router and BS over WAN. These include Radio Bearer control, dynamic allocations and radio resource management that are handled by base stations whereas gateway router handles distribution of paging messages and security.
Ethernet- 802.3 is used for grant wired access and Ethernet -802.11 is used for LAN access. The radio interface W-CDMA of UMTS is used extensively for cellular access. This arises the need for mobility to be implemented in the network layer as it can’t be handled by the lower layers. IPv6 mechanism is used for internetworking eliminating the need to use internal procedure for handover over any technology. This clarifies that no internal procedures are sustained in W-CDMA cells but the same IP protocol facilitates the movement among the cells.
The figure above illustrates a few handover potential in such a network to accommodate a moving user. The users can handover among any of theses technologies without splitting the network connection as well as supporting voice connections. The users have the opportunity to wander between administrative domains while having the capability to use their services across domains. There should be appropriate agreements among the existing domains. The service providers have the capability to track the usage of their consumers both on and off their network like while roaming.
The entire network inclusive of all management functions and applications was being employed with the IPv6 protocol over the Linux environment. AAAC and QoS subsystems were responsible for providing service to each user according to the SLA (Service Level Agreement). The software for these was extended resorting to a combination of existing implementations and newly included modules.
The 4 administrative domains are depicted in the figure with various access technologies. An AAAC (Authentication, Authorization, Auditing and Charging) system manages each administrative domain. “At least one network access control entity, the QoS Broker, is required per domain. Due to the requirements of full service control by the provider, all the handovers are explicitly handled by the management infrastructure through IP-based protocols, even when they are intra- technology, such as between two different Access Points in 802.11, or between two different Radio Network Controllers in WCDMA” . The network providers are responsible for all the network resources while the user control their local network, applications and terminal.
The key characteristics of this network architecture are :
A User : It refers to a company or a person with SLA constricted with a provider for certain set of services. The architecture is concerned about granting access to the users and not specific terminals.
MT (Mobile Terminal) : It is the terminal that gives access to the users for services. The network architecture can support terminal portability leading to the sharing of the terminal among various users though not at the same time.
AR (Access Router) : This is the generic mode of connection to the network that gets the name of RG (Radio Gateway) for basically wireless access.
PA (Paging Agent) : it is responsible for situating MT when it is idle and there are packets that need to be delivered to it.
QoS Broker : it is solely responsible for managing one or more AR’s. the AAAC system provides information that is used to control user access and access rights.
AAAC System : It is responsible for SLA including charging and accounting.
NMS (Network Management System) : It is responsible for overall network control and management. This entity guarantees and manages the accessibility of resources in the main network.
This network is proficient of supporting several functions namely :
Confidentiality both of user traffic and of the network control information
QoS levels guaranties to traffic flows
Inter-operator information interchange for multiple-operator scenarios
Mobility of terminals across multiple technologies
Mobility of users across multiple terminals
IMT-Advanced Network Architecture
The ITU specified IMT-Advanced (International Mobile Telecommunications Advanced) specifications for 4G standards. The data rate requirements for 4G service was set at 100 Mbps for high-level mobility communication and 1 Gbps for low-level mobility communication. Pre-4G technologies such as WiMAX and LTE have been in the market for a while. The most current version of these technologies do not accomplish the ITU requirements for 4G service. IMT-Advanced in compliance with the above 2 technologies are still under development and are namely called
The figure above illustrates the perception of a unified architecture developed by IMT-Advanced network built on IP as the common layer protocol. This interface facilitates services that allow the use of communication networks by the yet to be developed devices. With significant improvements in access speeds popular applications in wire line can be transferred under wireless networks in a identical flawless way.
Application of 4G:
Virtual Presence : 4G would provide user services to its users at all times irrespective of the fact that the user is on or offsite. The location applications of 4G would maintain a virtual database containing graphical representations and physical characteristics of metropolitan areas. This database can be accessed by users from anywhere by using appropriate wireless equipment, which would give the platform to appear virtual.
Tele-medicine : 4G would create a platform to monitor the health of patients remotely through video-conferencing with the capability for doctor’s assistance at anywhere and at anytime.
Crisis-Management Applications: Natural disasters leading to the breakdown of entire communications infrastructure needs to be restored as quickly as possible. In general it may take about a week or so to restore the services with 4G the communication services can be re-established in a couple of hours.
Virtual Navigation: It will provide virtual navigation to users so that they can access virtual database to visualize the internal design of buildings. It requires very high speed of transmission.
Tele-Geo Processing Applications: It would integrate GPS (Global Positioning System) and GIS (Geographical Information Systems) providing the users with location querying.
Education: 4G would provide the opportunity to the people across the globe to continue on-line education in a cost effective manner.
Multimedia-Video Services: 4G wireless technology is anticipated to deliver high data rates of multimedia services efficiently. There are two different types of video services: Streaming video and Bursting. Streaming is used only for real-time services and bursting is used for file download using a buffer and can take advantage of the entire available bandwidth.
An appropriate solution for operators who are looking to achieve monetary and technical efficiency in their upgrade path would be combining the 2G-3G with 4G network functions. A SGSN+MME node and a GGSN+SGW+PGW node can act as a node for both 2G/3G and a 4G network. There are various solutions that offer flexibility to sparate functions when the traffic grows. 4G evolutions can be eased out by slowly converting the current systems into an integrated 2G/3G/4G system and then ultimately to a 4G system. LTE and SAE requirements are ardently followed. This solution, so far provided by Cisco enables one to enjoy the advantages of the existing system along with the augmentation of 4G so that operators can still use the present system if and when desired. It can support 2G/3G today and through a software upgrade these solutions can support 4G functionality as well when LTE networks are deployed. Cisco claims that “operators need not perform forklift upgrades when evolving to 4G”. Existing SGSN,GGSN, or PDG can be upgraded to 4G functional elements – MME,SGW,PGW, and ePDG through the solution. The existence of a software upgrade solution to switch from 2G/3G to 4G shows the compatibility of 4G with 2G/3G.
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