Optimization of Quality of Service in 4G Wireless Networks


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4G radio access technologies should be able to
provide different types of IP services. These services rang from
narrow-band to broadband, from non-real-time to real-time,
and from unicast to multicast broadcast applications. When
the need arises for different levels of user mobility the access
systems are required with advanced capabilities of radio
resource management and Quality of Service (QoS). We
present, in this paper, the different QoS approaches by the
various wireless and connectivity’s networks as well as the
issues that will face their implementations in 4G.

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Optimization of Quality of Service in 4G Wireless Networks

  1. 1. ACEEE Int. J. on Network Security , Vol. 03, No. 02, April 2012 Optimization of Quality of Service in 4G Wireless Networks Firas Ousta*, Nidal Kamel*, Mohd Zuki* and Charles Sarraf** *Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia **mtctouch, Beirut LebanonAbstract—4G radio access technologies should be able to The structure of this paper is as follows, section 2 will providesprovide different types of IP services. These services rang from an Introduction to 4G, Overview of QoS and variousnarrow-band to broadband, from non-real-time to real-time, definitions and specifications, ITU, 3GPP, WiMAX, IP, etc…and from unicast to multicast broadcast applications. When will be presented in Section 3. We present, in section 4, anthe need arises for different levels of user mobility the accesssystems are required with advanced capabilities of radio overview of related work regarding End-to-End QoS in 4Gresource management and Quality of Service (QoS). We Mobile Networks. And finally section 5 will conclude bypresent, in this paper, the different QoS approaches by the summing up, pointing out the main issues and challengesvarious wireless and connectivity’s networks as well as the providing some guidelines for future worksissues that will face their implementations in 4G. II. 4G OVERVIEWIndex Terms—4G Mobile Networks, QoS, Mobile IP, WirelessNetworks In the past decade, the telecommunications industry has witnessed an ever accelerated growth the usage of mobile I. INTRODUCTION communications. As a result, the mobile communications technology has evolved from the so-called second generation Some of the most important trends, over the last decades, (2G) technologies, GSM in Europe, IS-95 (CDMA) and IS-136are the significant developments, deployments and the (TDMA) in USA, to the third generation (3G) technologies,tremendous growth in use of Mobile Networks from one side UMTS/WCDMA in Europe and cdma2000 in USA, beingand the Internet from the other side. Even more, this standardized by 3GPP and 3GPP2. Further the mobile industrytremendous growth, in both technologies, have a great impact has also witnessed an accelerated data transmission andon developing various applications catered for mobility and wireless Internet with higher and higher bandwidth supportedreal-time access that will fundamentally change the from GPRS (General Packet Radio System) to 3¼Genvironment of the telecommunications networks. These new technologies such as HSPDA (High Speed Downlink Packetdevelopment presents important challenges for the Access), through 2.75G EDGE and other packet data accesstelecommunication and Internet industries as well as the in CDMA and TDMA [2].current network architectures and infrastructures. An In the wireless access field, various technologies haveexplosive growth is expected in mobile communications [1], emerged such as Bluetooth which was developed as a newbased heterogeneous wireless access technologies, over the cable replacement technology providing a short-range (~10m),next decade with higher speeds and larger capacities than low bit rate (1Mbps) access in the 2.4GHz spectrums. IEEEprovided by 3G mobile systems. Various generations of also developed a wireless LAN (WLAN) access family ofcellular, broadband wireless, WLANs and WMANs will protocol IEEE 802.11a/b/g/… operating over 100m range andintegrate to support services which vary in bandwidth, delay, different spectrum access such as 2.4 GHz for 802.11b/g andand mobility 5.2 GHz for 802.11a as well as WiMAX (802.16) as WMAN. 3G mobile networks such as UMTS and cdma2000 from Nowadays, 802.11 and 802.16 have become widely popularone side and Wi-Fi (IEEE 802.11) and WiMAX (IEEE 802.16) and easy ways to provide wireless access for laptop andfrom the other side will allow operators to deliver high quality PDA users which can easily use VoIP for voicevoice, video and data services. Therefore 3GPP have defined communication, even many cellular phones and smart phonesmany paths to 4G migration including W-CDMA, UMTS, that have the capabilities to access WiFi have recently beencdma2000, WiFi and WiMAX based networks available in the market. The end-to-end Quality of Service (QoS) of an application Even though a universal consensus on what is going todepends on the overall performance achieved by the different be 4G is not yet reached in the industry or the literature, therecomponents, spread over many domains and owned by is a reasonable understanding of some characteristics of 4Gdifferent network and service providers, therefore the issue mobile networks [3]. Some of the accepted characteristicsof End-to-End QoS must be addressed when designing and are:deploying 4G networks and applications as well as mapping  All-IP based network architecture;between the different QoS parameters and messages at setup  Higher bandwidth;level as well as when roaming, including handovers, vertically  Support for different access networks, includingand horizontally.© 2012 ACEEE 6DOI: 01.IJNS.03.02.75
  2. 2. ACEEE Int. J. on Network Security , Vol. 03, No. 02, April 2012 WLAN and WiMAX technologies; ITU-T Rec. E-800 is widely used and referred to from most  Worldwide roaming capability; publications, its framework does suffer from not being  Full integration of “hot spot” and “cellular”; application-oriented and in many areas, too vague to use.  Support for multimedia applications. The ITU-T recommendation [6] focuses on four different Location management deals with tracking user mobility, points of view:and handling information about original, current and (if  Customer’s QoS requirements;possible) future cells and networks. Moreover it also must  Service provider’s offering of QoS;deal with authentication issues and QoS assurances [4]. Fig.  QoS achieved or delivered;1 depicts a logical architecture of 4G mobile networks. Such  Customer survey rating of QoS.architecture may consist of several Access Service Networks Relationships between these four points of views is(ASN) of different technologies. presented if Fig. 2. The ASN may be connected to Connectivity ServiceNetwork (CSN) of a visited network, which may be connectedover an IP-based network to the home mobile network.Connections to the Internet may occur at either the visitingnetwork or the home network. There are so many keychallenges to migrate the current systems to 4G. The researchareas that present key challenges to migrate current systemsto 4G are many but can be summarized in the following:Mobile Station, System and Service [4]. Stations’ mobility must be able to provide wirelessservices anytime, everywhere. This implies that roamingbetween different networks must be automatic and transparent Figure 2. The four viewpoints of QoSto the user. There are two major issues in stations’ mobility,location management and handoff management. However the main problems in this ITU-T Rec. were not being specific by defining target and/or thresholds values for acceptable criteria’s. Reference [7] defines a model for multimedia Quality of Service categories from an end-user viewpoint. By considering user expectations for a range of multimedia applications, eight distinct categories have been identified, based on tolerance to key parameters impacting the user such as delay and information loss, as shown in Fig. 3. Figure 1. Local architecture of a 4G Mobile Network III. OVERVIEW OF QOS Some of the major challenges of migrating the currentsystems to 4G are QoS provisioning and security servicesfor mobile users’ communication flows [4]. The QoS problemsconsist of two major issues: 1. Mapping QoS parameters over different access/ Figure 3. Mapping of user-centric QoS Requirements connectivity network at call setup. B. QoS in UMTS 2. Maintain these QoS when Users move to different access networks that may cause changes in Frameworks for QoS within UMTS [8] and end-to-end backbone and connectivity’s networks. QoS involving GPRS[17] have been provided by 3GPP. The The different radio access and connectivity networks main purpose in [8] is to specify the list of attributes applicablehave, through their standardization and specifications, to UMTS Bearer Service and Radio Bearer Service, as well asdefined QoS parameters and classes. describe the Quality of Service architecture to be used in UMTS networks, while [9] describes a the interaction betweenA. ITU the TE/MT Local Bearer Service, the GPRS Bearer Service, ITU-T [5] defines QoS as “the collective effect of service and the external Bearer Service, and how these togetherperformance which determine the degree of satisfaction of a provide Quality of Service for the End-to-End Service. Suchuser of the service”. Even though the definition of QoS in architecture is depicted in Fig. 4.© 2012 ACEEE 7DOI: 01.IJNS.03.02.75
  3. 3. ACEEE Int. J. on Network Security , Vol. 03, No. 02, April 2012 not cover the needed requirements for 4G. Many mechanisms have been therefore proposed to introduce traffic differentiation in IEEE 802.11 [10][11][12]. All these proposals require substantial changes to the current MAC protocol, leading to both higher channel utilization and effective differentiation among traffic flows. Although a wide consensus exists on a new standard, named IEEE 802.11e, including most of these mechanisms [13], more work is still needed to make this proposal fully operational and to fully support the 4G requirements. E. QoS in WiMAX (802.16) Similar to 802.11, the QoS in WiMAX networks is usually Figure 4. UMTS End-to-End QoS architecture managed at the medium access control (MAC) layer. [14][15][9] Also defines four QoS classes, corresponding to different detail the QoS support in WiMAX networks issues. Howevertraffic QoS requirements (mainly, delay tolerance): the latest specification of WiMAX, 802.16e [16] has defined  Conversational class. Audio and video 5 different categories for QoS as outlined in Table 1. communications with real time constraints. TABLE 1. WIMAX QOS CATEGORIES  Streaming class. This class comprises applications for downloading multimedia contents (audio and video) that are reproduced on-line.  Interactive class. Remote access applications, in which a human or a machine sends requests to a distant server and waits for an answer in a “reasonable” time.  Background class. A whole range of data applications for which delay is not a concern. A framework for IP end-to-end QoS negotiation and policyrequirements is also provided through the definition of alogical element, the Policy Decision Function (PDF), whichenables the coordination between events in the applicationlayer and resource management in the IP bearer layer, thatcan be realized by different ways including: signaling alongthe flow path (e.g. RSVP, LDP); packet marking or labeling(e.g. DiffServ, MPLS); interaction between Policy Control and/or Resource Management elements; and Service LevelAgreements (SLA) enforced by the border routers betweennetworks. F. QoS in IP networkC. QoS in cdma2000 In addition, the QoS of IP networks, both mobile and fixed The CDMA2000 standard is well poised to provide a IP/IPv6 are also very important issues in providing the End-simplified and an elegant solution to not only meets the needs to-End QoS in 4G mobile networks. During the last years theof user perception of end-to-end QoS at the application layer Internet community spent many efforts to develop an Internetbut ensures efficient utilization of system resources. QoS architecture based on various protocols such asCDMA2000 defines two modes of QoS [18]: Assured Mode Integrated Services (IntServ) [19], Resource ReservationQoS and Non-assured mode QoS. The different modes of Protocol (RSVP) [20] and Differential Services (DiffServ) [21].packet data services are in turn are determined by an exclusive However, RSVP and IntServ approach may not beset of Mobile Station specified QoS parameters. [17] Presents deployed in large-scale Internet backbones due to scalingan overview of the architecture and implementation of an and billing problems. Also, these protocols have beenend-to-end QoS for CDMA2000 networks designed in the context of fixed environments (hosts andD. QoS in WiFi (802.11) networks) and as result, they may not fully adapted to mobile Despite the great success of the IEEE 802.11 standard, environments when Mobile IP is used for mobilityseveral problems concerning security, power consumption management. As matter of fact, there are several issues aboutand quality of service of wireless LANs remain partially QoS in Mobile IPv6: Handover and roaming in heterogeneousunsolved. Although the current standard includes an optional QoS domains, roaming between dissimilar media and notraffic differentiation mechanism based on polling, it does advanced resource reservation [22] [23].© 2012 ACEEE 8DOI: 01.IJNS.03.02.75
  4. 4. ACEEE Int. J. on Network Security , Vol. 03, No. 02, April 2012 IV. END-TO-END QOS IN 4G None of works presented in Section (IV) has addressed the full scope of End-to-End QoS in 4G networks. Theses works General and En-to-End QoS in mobile heterogeneous have either addressed some, most likely 2, of the accessenvironments have been studies and may architecture have networks or addressed the QoS for specific applications suchbeen proposed. In [24] the authors presents a comparative as multimedia.analysis of alternative approaches that have been developed The following are some issues related to QoS that needby IEEE, 3GPP and others for handover of PSTN and Internet to be addressed in order to have smooth migration from thesessions among multiple wireless technologies including current mobile systems to 4G mobile networks:UMTS, WiFi, WiMAX, Mobile-Fi and WPANs. [25] proposes Some standards need special measurement equipments.a possible architecture of integrating UMTS and 802.11 It makes very difficult for normal users to verify theWLAN. parameters of their Service Level Agreements. New functionalities and interfaces in addition to some  Mappings between different standards andextension to the existing SIP signalling are defined in [26] to specifications (ITU, ETSI, UMTS, IETF, WiMAX, WiFi,resolve some of the existing problems existing in UMTS that cdma2000, etc…) are not clear.don’t let End-to-End QoS control between different Mapping between Telecom standards and IP standardstechnologies and domains. The authors of [27] presents a is not clear. The 3GPP specifications have addressednetwork and mobile client architecture that provides seamless this at very high level by defining a PDF element androaming and mobility while maintaining connectivity across, the need for coordination; however the specificUMTS and 802.16 these wireless networks providing quality mechanisms have not been addressed.of service (QoS) support. [28] proposes a mechanism that  Target values and thresholds for End-to-End QoSsupports Always Best-Connected (ABC) Quality of service parameters shall be defined in clear way. These values(QoS) to the application in a heterogeneous network. The should be simple enough for the end-user to measureheterogeneous network consists of IEEE 802.11e WLAN and and manage.IEEE802.16d WiMAX access networks.  Applications, that are currently exist, in the service A policy-based multi-domain QoS management provider domain (the Internet) may need somearchitecture that provides consistent QoS control over an modifications to communicate with the PDF elementintegrated UMTS and WLAN system is proposed in [29]. and other QoS mechanisms of different Access Service[30] describes a global QoS architecture for multimedia traffic Networks.in mobile heterogeneous environments covering WiFi and  Mobility, through routing, link error rate, availableWCDMA. This architecture supports both multiple access bandwidth and throughput, service and user location,networks and multiple service provider scenarios. The security, handoff, may add other complications to QoSarchitecture is able to provide QoS per user and per service, management and measurements and need to addressedimplementing the notion of a user profile associated with among the different Access Service Networks as wellcontrol element functions. A solution allow for two-hop as the Connectivity’s Networks and IP based networks.wireless paths between WLAN and 3G systems, and Roaming agreements between Access Service Networksperforming control over-high layer issues, specifically (ASN) providers, Connectivity Service Network (CSN)focusing on End-to-End QoS provisioning is proposed in providers and external backbone providers should[31]. consider the promised QoS of the end-users. The authors in [32] present architecture for supporting  QoS measurements and analysis should be measuredEnd-to-End QoS in WiFi and WCDMA based networks. This in real and simulated networks based on differentQoS architecture is able to support multi-service, multi- standards and proposals in order to better define theoperator environments, handling complex multimedia services, QoS architecture, attributes, parameters and mainly thewith per user and per service differentiation, and integrating target values.mobility aspects. VI. CONCLUSIONS V. DISCUSSIONS Though there exist different architectures and mechanisms One of the major problems, in migrating the current that have been proposed to support QoS in heterogeneoussystems to 4G are End-to-End QoS provisioning. These networks, there are a number of issues that need furtherproblems could be addressed from two different angles: studies for smooth migration from the current mobile systems  Mapping QoS parameters over different access/ to 4G mobile networks. Among these issues is the mapping connectivity networks at call setup. between different standards, mobility, routing, and handover  Maintain these QoS when Users handover, both between different access service networks and connectivity vertically and horizontally, by moving to different networks. Access Service Networks. Moving across different Access Service Networks may cause the route to move to different Connectivity’s service Networks and external backbone networks.© 2012 ACEEE 9DOI: 01.IJNS.03.02.75
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