Continued improvement in semiconductor and computing. technologies brought exponential growth to wireless industry. The

Transcription

1 23 Chapter-1 INTRODUCTION Continued improvement in semiconductor and computing technologies brought exponential growth to wireless industry. The huge number of advance mobile devices and integrated applications on it are available at economy price. This increasing popularity has brought the mobile manufacturers and operators with challenges from various aspects. There will be paradigm shift in the way we live, work, and play with these smart innovative devices. Next Generation Networks (NGNs) will have an IP-based infrastructure that supports heterogeneous access technologies. This has enabled people and empowered them to communicate with each other on intelligent environments. Tomorrow s consumers would be offered with wide range of services on mobile through various types of networks and schemes everywhere and anytime. The realization of this type of ubiquitous environment has been possible with convergence of different standards on common platform. This convergence opened up the new challenges and opportunities for research community to address the various challenges such as Mobility Management (MM), Quality of Service, Security, Unified Billing etc. We therefore focused our research to address some of these challenges. In this introduction chapter of the thesis, we provide the evolution of wireless communication

2 24 networks, benefits of convergence in NGNs, 4G networks, challenges in 4G networks, mobility, and billing issues in 4G Networks, Accounting Charging Billing (ACB) issues and challenges,motivation, and objectives of the study and organization of the thesis. 1.1 Evolution of Mobile Wireless Communication Networks The mobile wireless communications evolved, transformed and revolutionized the complete way of communication. In this section, we see the technologies that changed from 1G to 3G.We also see the different standards in each generation and the impact of the same on user services. 1G started in 1980 and all the technologies used analog radio signals. Voice was the main service and traffic in 1G.The various standards used in 1G and their respective features are shown in Table G took over 1G in 1990 with digital radio signal technology, which delivered rich set of features and services with global roaming. The voice service was still the main traffic in 2G. Technologies like GPRS and EDGE were introduced as intermittent technologies (also known as 2.5G & 2.9G respectively) to provide higher data services over existing GSM infrastructure [1] Presently, 2+ generation technology is at transition and to be replaced by 3G that works with the combination of circuit switching plus packet switching. 3G systems promise high rate of

3 25 transmission services, involving voice, facsimile and Internet data transfer capabilities. Generation Family/stan dardization body 1G (1981) 2G ( ) 2.5G ( ) 2.75G (2000) ETSI/3GPP GSMand GSM/CSD 3GPP2 CDMA One (IS- 95 A and B) Others D-AMPS(IS-54 and IS-136), PDC,PHS GSM/3GPP GPRS:HSCSD PS data 3G(IMT- 2000) ( ) 3.5G (2005 and Present 3.75G (2007- present) 3.9G (2010) Technologies Features IMT,AMPS,TAC S Extended coverage, Poor quality, drops. Better mobility, Roaming, Better quality, SMS + low bit rate data 2GPP EDGE /EGPRS Higher data rate, 3GPP2 CDMA2000 PS data 1 RIT(IS-2000) 3GPP 3GPP2 UM TS: WCDMA TD-CDMA TD-SDMA Higher data rate, Global Roaming. 3GPP 3GPP2 HSDPA, HSUPA Higher data rates, less latency,more capacity 3GPP HSPA+ Higher Data rates, 3GPP2 CDMA2000 3x more capacity (EV DO-Rev. B) 3GPP 3GPP-LTE Higher Data rates, Other more capacity, more throughput IEEE e 2005, Flash OFDM, IEEE Table 1.1 Generation evolution with technologies of Mobile communications. It also provides innovative services such as hyper media entertainment and geography centred instant services. The

4 26 standard defined for 3G was IMT-2000 by ITU. The currently available technologies that fulfil these service requirements are CDMA2000, WCDMA, TD-CDMA and EDGE [4]. 3G optimizes the bandwidth usage with these above technologies. Table 1.1 shows these generations and their respective technologies and features. The deployment of 3G was slow due to challenges like any-time, any-where connectivity for end user. This idea connect anytime, anyhow, anywhere could be possible with the convergence of networks on IPv6 core. This would be the main theme for 4G wireless networks [10]. 1.2 Benefits of Convergence in NGN mobile Communications The IP based networks are highly scalable and easily deployable. Today s many applications are easily compatible with IP based networks. The IP in-built applications are easily accessible on WWW. The converged IP core network over comes interoperable and provides an intelligent single common open platform for future communication. The ITUs OECD report [6] proposes Convergence model for NGN (shown in Fig 1.1), wherein the convergence taking place at different levels. The model clearly shows the convergence of all sectors such as Internet, telecom market and all the technologies on IP core network. This convergence will transform the way the application interacts to each other seamlessly. The exponential growth of Internet will enforce this convergence in near future.

5 27 Fig 1.1 Convergence model [6] 1.3 4G Networks The 4G Network would be convergence of heterogeneous networks over IPv6 core. Recent survey done on 4G deployment status across globe shows that there are 22 LTE technology networks in 16 countries; nearly 50 launches expected before end of 2012, 86 in trail and 168 planned for deployment [13]. When fully implemented, users of 4G devices will have the ability to access to applications ranging from basic voice communication to seamless real time streaming video at very high speed [2]. The technologies employed by 4G will be LTE Advanced, WiMAX, and Ultra Mobile Broadband

6 28 etc. 4G will provide high throughput transmission with theoretical 100Mbps download. From the user perspective, the 4G would be offering the features such as user friendliness, user personalization, user trust and security, lower power consumption, low cost, good Quality of Service, etc.,[10].typical 4G network is shown in Fig 1.2 Fig 1.2 Typical 4G Convergent network Features of 4G Networks The key features [11] of 4G networks revolve on the theme of Anytime, Anywhere and Any service connectivity.

7 29 User mobility across different multiple interfaces. User mobility and device mobility across multiple heterogeneous technologies Seamless information exchange among Inter-operators QoS levels guaranties to traffic flows (New SLAs will emerge with respect to QoS) Dynamic and instant network monitoring functions for optimum usage of resources. High throughput with minimum resource consumption The 4G infrastructure involves core technologies that will facilitate all the above features and accomplish ubiquitous environment. The following are the key technologies that will enable 4G implementations over this infrastructure [12] 1. Orthogonal Frequency Division Multiplexing (OFDM) [35] The main goal of 4G is to provide high-speed wireless broadband services. 4G is equipped with the proper arrangements at the physical layer to meet all the demands of those applications that are sensitive to high bandwidth. OFDM has the ability to optimize the consumption of resources. Due to the orthogonal nature of the carriers used for different channels, it is possible to overlap the bands on each other and still recover them in the receiver without losing any quality. Because of this, OFDM is very effective in saving bandwidth. In low bandwidth systems where the demand for

8 30 spectrum is very high, OFDM comes naturally as the first choice. Therefore, 4G handles bandwidth efficiently. OFDM also efficiently handles Inter-Symbol Interference (ISI) problem, which is a big problem that reduces quality of services in present broadband services [35]. 2. Software Defined Radio for the 4G System [9] Software defined radio (SDR) is an emerging radio technology that can be used in various digital networks and can be controlled and programmed through software. 4G would be using SDR. SDR can handle the implementation of multi-mode, multi-band and multistandard terminals. SDR also has the ability to support wireless applications in various networks like Bluetooth, WLAN, GPS, radar, WCDMA and GPRS[9]. 3. MIMO Antenna Systems for 4G[12] 4G like its predecessor 3G would be using the advanced versions of the MIMO Antennas. The antennas used for the 3G system were smart enough to take care of many advanced operations at the signal level. This system must continue for 4G as well, and may even be made more sophisticated for 4G, as the number of signallevel decisions would be far greater in the case of 4G compared to 3G [12].

9 Challenges in 4G Networks With many technologies facilitating 4G communications, 4G still possess many challenges. Few challenges illustrated as below [12]. Design of user terminal: The user terminal needs to support multimode operations. The device should be capable to auto reconfigure among all the modes to adjust itself to diverse wireless networks.the terminal should be equipped to choose preferred network operator for specific service. Service discovery over multiple interfaces will be the biggest challenge in 4G networks. SDR based terminal is proposed to be used, but needs to evolve with respect to 4G deployment. Seamless mobility management: 4G promises Anytime, Anywhere and Any service connectivity. Two major challenges such as Handoff management and location management need to address to fulfill above promises. Security: All the existing security mechanisms and protocols are designed to address specific services. We need flexible, compatible integrated security framework, which can dynamically reconfigure and provide strong security. QoS provision on converged infrastructure: As discussed earlier 4G is integrated heterogeneous network. The existing QoS designs are done based on specific system or technology in mind. These solutions do not work anymore in 4G. It

10 32 requires an integrated approach to assure end-to-end good QoS. Unified Billing: 4G will provision independence to user to choose any network operator for any specific services. In this scenario, the user should have a provision to get single unified bill for the service used from varied network operators. 1.5 Mobility management challenges in 4G networks Mobility management is the critical and important issue of 4G networks. In this section, we have highlighted few MM challenges as below [57]. Choice of BEST access technology 4G envisioned to provision user to choose the any service provider for any specific service; mobility management mechanism should facilitate user to choose the BEST radio access technology for the service the user looking for. The handoff management unit need to measure the BEST access technology and handover the user connectivity for that service. Therefore, network selection mechanism should consider the type of service, QoS parameters, etc., before handover establishment.

11 33 Seamless mobility across multiple access technologies The other design challenge that concerns in MM is to develop seamless connectivity mechanisms that support real time applications on run time. These mechanisms need to exhibit low handoff latency with minimum packet loss Provision of multimedia services on mobility 4G promises multimedia services, transmission and handover of multimedia services from one access point to other is of great challenge in 4G networks. There will be radical changes in QoS of networks provisioning these types of services. Network quality will affect the quality of these sensitive services. Therefore, the MM should support multimedia services. Therefore, we require a new level of mobility support to address these new challenges in 4G networks. It is not just sufficient to upgrade or change the existing protocols and mechanisms to address the above emerging issues. We require new architectural approach and principles for provision of MM in 4G networks. Therefore, this dissertation has proposed novel mobility management architecture that is suitable for 4G networks. The architecture mainly designed to address user mobility scenario and the issues related to only this context

12 Handoff Management over MIPv6 Handoff management techniques are vital for mobility provisioning in 4G networks. The handoff management in ubiquitous environments is more complex than that in traditional environments. The complexity is because of some scenarios that can occur when a mobile device changes its attached access point (handover) during service delivery. Conventionally, handoff management handled by link layer in 2.5G and 3G. Since 4G will all be IP based architecture, link-layerindependent solutions are required at network layer for realizing IP mobility support over wireless IT infrastructure. To address this issue, MIP and consequently MIPv6 proposed and standardized by IETF [19]. Handoffs could be broadly classified as horizontal handoff, vertical handoff, [20], soft handoff and hard handoff [26]. Mobility support for IPv6 is still very naive and much development has to be yet carried out towards it realization and acceptance. MIPv6 a layer 3 protocol defined by RFC3775 [19] provides support for mobility. In recent years many protocols were proposed within IETF, each protocol has its own strengths and weakness. Debashis and Amitava [27] have classified all these protocols based on their operations at different levels as shown in the Fig 1.3 below. Few

13 35 popular among them are FHMiPv6 [21], PHMiPv6 [22], key based handoff mechanisms [20], RSS based handoff mechanisms [24]. This thesis has done extensive literature survey on handoff management protocols and decided to implement handoff management over MIPv6 protocol. Many researchers have proposed handoff management implementations on Linux platforms. Mobility support on windows based systems have seen less or negligible growth. Our work presented here discusses the handoff techniques using the Fast Binding Acknowledgement (FBA) algorithm on a window s platform. Fig 1.3 Classifications of Mobility Protocols [27]

14 Accounting, Charging, Billing issues and challenges in 4G Networks As discussed earlier the convergent 4G network will give independence to user to choose any network operator for any service and get unified single bill for the varied service used from different network operators. Therefore, ACB on integrated platform will be of greater challenge. Today billing models are simple and confined to home network operator. The subscribers mainly charged based on flat rate for the duration of the connectivity. There will paradigm shift in ACB approaches. Assuming convergence happening at all levels, Accountability and Billing of such convergent networks is an open issue of research. Billing Accounting and Charging Architectures based on Authentication, Authorization, and Accounting (AAA)[18] have been used by many researchers. Intra Network operation currently supports handoff only while on roaming. The billing of Intra Network operators is achieved on the basis of the Service Level Agreements (SLAs) existing between them [28] [29]. HP, Cisco, and AT&T also provide efficient scalable solutions, which are currently utilized by the network operators [30] [31]. Flat Billing Architectures [17], Compensation Billing Architectures [33], and reusable ticket architectures [34], have been analysed for the work presented. The use of third party for accounting, charging and billing is proposed by ANWIRE Project [32] and has been considered by researchers.

15 37 From the existing business models, it is evident, an external entity is required to monitor and provide for convergent services from varied network operators to the users. The billing architectures studied provide solutions for varied problems but no architecture could provide a complete solution offering unified billing, financial security, and transparency in accounting and grievance management features. The proposed Convergent Framework Architecture (CFA) addresses many of the issues related to unified billing. 1.7 Motivation and Problem Statement The convergence in 4G networks will drive all proprietary hardware, software, and protocols to a standards based model that benefits all the stakeholders of communication industry and mainly the end user. With this happening in near future in 4G networks, the user will have the provision to choose varied services from different service providers. This service oriented intelligent network environment will pose new integration challenges such as seamless mobility, lower latency, enhanced reliability, and higher throughput and unified billing etc... It is proposed in many research forums that it is not just sufficient to upgrade or change the existing protocols and mechanisms to address the above emerging issues. We require new architectural approach and principles to fulfil the future needs for diverse mobile

16 38 communication. We find many proposed research implementations are based on Linux environment. We see very few research implementations done on windows platform. Therefore, this thesis has proposed novel mobility management architecture that is suitable for 4G networks with implementation on windows environment. The consumers in 4G networks would have the freedom to select a service or services provided by one or many providers and obtain a single bill based on their usage. This would result in an integrated billing Service Oriented Architecture (SOA), where consumers be charged based on their usage of different services from varied service providers. Therefore, accounting, charging and billing of such convergent networks is an open issue of research. There is very less research work happening in this direction. This research work has also proposed a convergent framework architecture that constitutes a trusted convergent operator on IPv6 core that is responsible for unified bill generation. 1.8 Objective and Scope The research work proposed here addresses issues related towards the realization of 4G networks. Very few deployments of 4G networks exist and are on a very small scale [13]. Seamless Mobility

17 39 management and unified billing provision are major challenges in converged 4G networks. Therefore, the work presented here mainly addresses issues related to Mobility Management Architecture for 4G Networks over MIPv6 Accounting, Charging and Unified BillingArchitectures in 4G networks Mobility Management Architecture for 4G Networks over MIPv6 4G networks integrated over an IPv6 core need effective Mobility management architecture to reduce handoff latency and provide better QoS. A Handoff Management Unit (HMU) is introduced which incorporates the Fast Binding Acknowledgement (FBA) algorithm to provide seamless mobility management. The HMU is capable of handling both horizontal handoff and vertical handoff operations across interfaces connected to the mobile user node. The experimental study concentrates on creating test beds created on the Windows platform with incorporation of varied interfaces through virtual routers to support IPv6 switching. The performance study of this architecture conducted and demonstrated with the simulation results. The experimental evaluation conducted exhibited average handoff latency time of approximately 1sec.

18 Unified Billing Architecture for 4G Networks Currently users are compelled to use the services provided by the network operators to whom they are registered. 4G networks would provide freedom to use services from multiple network operators without prior subscription. Billing of such complex heterogeneous networks is a major issue. In the research work presented here, we have introduced Convergent Framework Architecture (CFA) that constitutes a third party secure agent named Convergent Network Operator (CNO) to facilitate unified billing. The CNO introduced is assumed to be governed by the local or international governing bodies like ITU, IETF, IEEE, 3GPP etc. A prototype implementation is further discussed and the generation of unified billing for a user utilizing varied services from different network operators is demonstrated. 1.9 Organization of the Thesis Remaining part of the thesis organized as below: Chapter 2 presents the literature survey conducted on the realization of 4G networks. The related work started with the IP core networks and the advantages of transition from IPv4 to IPv6.We have discussed the need for convergence and the work happening at different standardizing bodies towards realization of the same. Different handoff management schemes and their performances with respect to different parameters are discussed. We have

19 41 discussed different existing billing models and their features available with home network operators. The discussion also supplements with open research work done by other researchers towards unified billing in future Next generation networks. Chapter 3 introduces design and performance of our proposed Mobility Management Architecture that is suitable for 4G networks. At the outset, the chapter provides the problem scenario considered and the problems associated with it for mobility. The working of the proposed architecture is discussed by describing the functions of HMU (Handoff Management Unit) and FBA (Fast Binding Algorithm). We have discussed the simulation environment used to test the proposed mobility management architecture and presented various analysis and results on Horizontal handoff, Vertical Handoff and Handoff between multiple interfaces. Chapter 4 introduces design and performance of our proposed Unified Billing Architecture that is suitable for 4G networks. We have discussed the operations of our proposed Convergent Framework Architecture (CFA) with an analytical model. The performance of CFA is discussed and the results for different billing scenarios are generated and analyzed. Chapter 5 concludes the thesis by providing few future directions for the proposed work.