4G: FUTURE GENERATION MOBILE

ABSTRACT:

           In the area of mobile systems, things usually are discussed 10 years in advanced. So for the aim of beginning 4G around 2010, it is the time to discuss 4G now. This paper describes architecture for heterogeneous wireless-wired networks. This architecture applies an “all-IP” paradigm, with embedded mobility of users and is able to provide quality of service per-user and per-service. On the way to 4G-system architecture, major issues like requirements, adaptability are considered. 

Due to the heterogeneity of the access technologies, the Internet Protocol version 6 (IPv6) is being targeted as the common denominator across multiple access technologies. This paper also focuses on adaptability in terms of reconfigurability therefore; abstraction layers have been considered which consist of adaptable cooperating components grouped by open platforms rather than rigid system layers. The proposed architectures are multimode device, overlay network, common mode network. Architecture supports network services, in a secure and auditable way. Both user-to-network interfaces and inter-operator interfaces are defined, so that multiple service providers can interoperate. For seamless handover between different systems in future wireless environment it is necessary to have reconfigurable terminals so architecture of mobile device has been considered.  An overall 4G-feature framework based on the kernel concept of integration, in which two key features (diversity and adaptability) of the three targets (terminals, networks and applications) are described in detail.

1. Introduction:

This paper describes architecture for Service in heterogeneous wireless-wired networks. This architecture applies an “all-IP” paradigm, with embedded mobility of users. The architecture allows for multiple types of access networks, and enables user roaming between different operator domains. The architecture is able to provide quality of service per-user and per-service. In future everybody should have seamless to all services independently of location and terminal type. Pioneers of 4G are focusing on creating a convergent network that offers seamless IP connectivity over several interfaces (WLAN, OFDM, W-CDMA) and wireless networks with very high data rates. Further technology developments will contribute to an increase in the convergence of the various access technologies leading to the seamless access paradigm and the network evolution toward “all IP” that will reduce network deployment. In future, Internet, cellular systems, intranet, etc will merge into a whole seamless wireless internet, whose core network is IPv6 backbone.

2. Mobile Device Architecture:

The main platforms of the mobile are :
·         Smart card middleware platform which provides subscriber identities   and a highly secure execution environment.
·         Smart card networking platform, which provides networking, functions like addressing and authentication.
·         Programmable radio platform for one or more radio standard families & Native operating system platform, providing real time support. 

3. Architecture of 4G mobile communications:

The overall 4G architecture discussed in this paper is IPv6-based, supporting seamless mobility between different access technologies. Mobility is a substantial problem in such environment, because inter-technology handovers have to be supported. In our case, we targeted Ethernet for wired access; Wi-Fi  for wireless LAN access; and W-CDMA - the radio interface of UMTS - for cellular access. With this diversity, mobility cannot be simply handled by the lower layers, but needs to be implemented at the network layer. An "IPv6-based" mechanism has to be used for interworking, and no technology-internal mechanisms for handover, neither on the wireless LAN nor on other technology, can be used. So, in fact no mobility mechanisms are supported in the W-CDMA cells, but instead the same IP supports the movement between cells. The users/terminals may handover between any of these technologies without breaking their network connection, and sustaining voice connections. The users can further roam between administrative domains, being able to use their contracted services across domains if only appropriate agreements between those domains exist. The service providers are be able to keep track of the services being used by their costumers, both inside their own network, and while roaming. 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, or between two different Radio Network Controllers in WCDMA. All network resources are managed by the network provider, while the user only controls its local network, terminal, and applications. Summarizing the key entities are:

·         A user - a person or company with a service level agreement (SLA) contracted with an operator for a specific set of services. Architecture is for user mobility, so access is granted to users, not to specific terminals.

·         A MT (Mobile Terminal) - a terminal from where the user accesses services. It supports terminal portability, i.e. a terminal may be shared among several users, although not at the same time.

·         AR (Access Router) - the point of attachment to the network, which takes the name of RG (Radio Gateway) - for wireless access (WCDMA).

·         PA (Paging Agent) - responsible for locating the MT entity when it is in "idle mode" while there are packets to be delivered to it.

·         QoS Broker - entity responsible of managing one or more ARs/AGs, controlling user access and access rights, provided by the AAAC System.

·         AAAC System - the Authentication, Authorization, Accounting and Charging System, responsible for service level management (accounting, charging), Metering entities are also considered an integral part of this AAAC system.

·         NMS  (Network Management System) - the entity responsible for managing and guaranteeing availability of resources in the Core Network, and control.

4. Architecture of Access Network:

Network architectures will play a key role in implementing the features required to address these issue. One of the most challenging problems facing deployment of 4G technology is how to access several different mobile complexities without requiring wireless network modification or employing networking devices. Each network can deploy a database that keeps track of user location, device capabilities, network conditions, and user preferences, depending on handling of quality-of-service (QoS).

Possible 4G wireless network architectures are:

·         A multimode device lets the user, device, or network initiate handoff between networks without the need for network modification.

·         An overlay network—consisting of several universal access points (UAPs) that store user, network, and device information—performs a handoff as the user moves from one UAP to another.

·         A device capable of automatically switching between networks is possible if wireless networks can support a common protocol to access a satellite-based network and another protocol for terrestrial networks.

4.1 Multimode devices:

One configuration uses a single physical terminal with multiple interfaces to access services on different wireless networks. Early examples of this architecture include the existing Advanced Mobile Phone System/Code Division Multiple Access dual-function cell phone and the emerging Global System for Mobile telecommunications/Digital Enhanced Cordless Terminal dual-mode cordless phone. The multimode device architecture may improve call completion and expand effective coverage area. It should also provide reliable wireless coverage in case of network, link, or switch failure, incorporates most of the additional complexity without requiring wireless network modification or employing networking devices as shown in fig. 4. The user, device, or network can initiate handoff between networks. Each network can deploy a database that keeps track of user location, device capabilities, network conditions, and user preferences.

Fig. 4 Multimode Device Concept

4.2 Overlay Network

In this architecture, a user accesses an overlay network consisting of several universal access points. UAPs in turn select a wireless network based on availability, QoS specifications, and user defined choices. It performs protocol and frequency translation, content adaptation, and QoS negotiation-renegotiation on behalf of users. This, rather than the user or device, performs handoffs as the user moves from one UAP to another as illustrated in fig 5 below. A UAP stores user, network, and device information, capabilities, and preferences also can keep track of the various resources a caller uses, which supports single billing and subscription.

Fig. 5 Overlay Network Concept

4.3 Common Access Protocol

This protocol becomes viable if wireless networks can support one or two standard access protocols. One possible solution, that require networking between different networks, uses wireless asynchronous transfer mode. To implement wireless ATM, every wireless network must allow transmission of ATM cells with additional headers or wireless ATM cells. One or more types of satellite-based networks might use one protocol while one or more terrestrial wireless networks use another protocol as illustrated in figure below.

Fig. 6 Common Access Protocol Concept

4.4 Quality of Service

Supporting QoS in 4G networks will be a major challenge due to varying bit rates, channel characteristics, bandwidth allocation, fault-tolerance levels, and handoff support among heterogeneous wireless networks. QoS support can occur at the packet, transaction, circuit, user, and network levels.

·   Packet-level QoS applies to jitter, error rate. Network resources such as buffer space and access protocol are likely influences.

·   Transaction-level QoS describes the time it takes to complete a transaction and the packet loss some may be time sensitive, while others cannot tolerate.

·   Circuit-level QoS includes call blocking for new as well as existing It depends primarily on a network’s ability to establish and maintain end-to-end circuit. Call routing location management are two important circuit-level attributes.

·   User-level QoS depends on mobility and application type. New location may not support minimum QoS needed, even adaptive applications.

5.  Focal Area for 4G researches:

To provide high data rates everywhere in a way i.e. affordable to the public. The cost of providing wireless bandwidth everywhere, with the current “cellular” design paradigm, should proportional to the data rate; i.e., the cost per bit is almost constant, independent of the instantaneous data rate of the system.

5.1 Wireless Infrastructure Architecture

Propagation at VHF suffers high free-space loss, strong shadowing by humans, and high attenuation by common building materials. The number of wireless access points (APs) required achieving sufficient coverage is therefore high.

5.2 Smart Antennas

In order to provide high date rates at a low cost, smart antenna systems have been proposed for short-range WLAN-type systems. Using the 60 GHz band requires an increased number of access points, but may allow inexpensive radio access equipment. Systems at 5 GHz offer greater range, and have the advantage that several users can share one access point, which offers flexibility for the operator at the cost of more complex access points. 

5.3 Seamless IP Mobility Support for Mobile Applications

Since the network infrastructure is not deployed in an orderly fashion, protocols need to be flexible and robust. IP mobility will be an indispensable feature of future mobile communications services. Although both mobile communications and the Internet have been extremely successful during the last decade, the seamless integration of these two is still a great challenge in both areas.

6. Conclusion:

Although 4G wireless technologies offers higher bit rates and the ability to roam across multiple heterogeneous wireless networks, several issues like secure access and service require further research and development. Mobile communication of 4^th Generation will come around 2010, with data rate of 20M-100Mbps, fully coverage services and ubiquitous mobile access. Core feature of 4G are described as diversity and adaptability of the target, leading to seamless diversity.  IPv6 backbone will be the core future wireless Internet. IPv6 is of major interest with remarkable growth of the Internet.  Being architecture specially targeted to support real time communications over packet networks. It is of vital importance that security mechanisms, and in particular user authentication, are integrated for the next generation of networks and services. Based on a single electronic device representing the user’s identity we envision a seamlessly integrated whole of different networks and services, allowing the end user to access information anywhere anytime with only a single service subscription. 4G mobile communication systems will provide an efficient and cost-effective solution to future wireless multimedia communications. 4G would be driven by intelligent software auto configuration, which will have frequency 3G-5GHz or 60 GHz unlicensed band has been proposed for this purpose, offering at least 10-20MHz or 5 GHz of available bandwidth respectively.