Policy Based Architecture for 4G Wireless Networks S.Rajeev1 Member IEEE, K.V.Sreenaath2, A.S.Bharathi Manivannan3 1

Department of Electronics and Communication Engineering, PSG College of Technology, Coimbatore 2 Software Engineer, Motorola India Pvt. Ltd., Bangalore 3 Software Engineer, Caritor India Pvt. Ltd., Chennai email : [email protected], [email protected], [email protected]

Abstract – Over the technologically heterogeneous infrastructure, a plethora of disparate services and multimedia applications will have to be deployed in an efficient yet flexible manner, using an all IP backbone. Mobile users will expect seamless global roaming across different wireless access systems and ubiquitous access to personalized applications and content via a universal user-friendly interface that are provided by 4G wireless Networks. In such an environment, an adaptable and intelligent service provisioning mechanism that focuses on user driven, user controlled and contextaware applications are necessary. This could be achieved through a Policy based approach that co-ordinates various business players in such a dynamic environment. In this paper, we propose Policy Based Architecture for 4G Wireless Networks. Keywords –4G Wireless, Policy Provisioning, QoS, Service Level Agreement.

I.

INTRODUCTION

With the rapid development of wireless communication networks, it is expected that fourth generation mobile systems will be launched in within decades. 4G networks are all-IP based heterogeneous networks that has a vision of “always on, always best connected” mode of communication [1]. Service provisioning in such an environment is cumbersome. Thus we go for a policy-based approach for service provisioning in 4G networks. Policies are rules that govern the choices in the behavior of the system. Policies define what actions need to be carried out when specific events occur within a system, as well as what resources must be allocated under specific conditions. Policy setting and implementation, approval workflows, physical resource setup/teardown (provisioning), account maintenance, reconciliation of actual resource assignments with approved user lists, audit, and overall service management are some example of those. They are together called as Policy-based provisioning [2]. This paper is organized as follows: Section 2 introduces to the emerging issues in 4G wireless networks. Policy based architecture for service provisioning in 4G networks is given in Section 3. SLA Trading Algorithm is given in Section 4. Policy specification for SLA Trading and Billing Users are presented in Sections 5 and 6 respectively. Finally, Section 7 concludes the paper.

II. KEY ISSUES AND CHALLENGES IN 4G WIRELESS NETWORKS All printed material, including text, illustrations, and charts, must be kept within a print area of 6-7/8 inches (17.5 cm) wide by 8-7/8 inches (22.54 cm) high. Worldwide many mobile operators, industry experts, and researchers have diverse visions of potential 4G features and implementations. In general, 4G systems are expected to provide at least the following features: A. Service Personalization: In order to overcome the saturated mobile communications market, operators will seek new 4G users in widely different locations, occupations, and economic classes. In order to meet the demands of these diverse users, service providers should design personal and highly customized services for them. B. Context-aware applications: The behavior of applications adapts itself to user profile/preferences, terminal/ network capabilities, user environment and mobility. This is possible by the use of software-defined radio and smart antennas. C. Multimedia Support: The user must be able to receive high data rate multimedia services (e.g. video streaming). This requires high bandwidth and data rate. D. Untethered connectivity and global roaming: The end user terminals must be compatible with any technology. The user experiences seamless connectivity when he moves for example from GPRS to WLAN. High Network Capacity: Network capacity should be at least 10 times that of 3G systems. This will quicken the download time of a 10-Mbyte file from 200 s on 3G to 1 s on 4G, enabling high-definition video to stream to phones and create

a virtual reality experience on high-resolution handset screens. Nonetheless, there are some challenges that raise the bar on service management and provisioning in 4G networks. The possible cases are as follows E. Selection of Wireless Access System: The user terminals must be able to select automatically the best wireless access system. Given that wireless access systems differ in their strengths and limitations in terms of coverage area and supported bandwidth - mobile terminal and access network capabilities should also be considered along with other important flavors of context information (e.g., user location, mobility patterns) for the efficient adaptation of the service provision process to each particular environment and situation. F. Quality of service & Intelligent Billing: A flat rate billing as in 3G systems, based on subscribed services, call durations, and transferred data volume is usually enough in many situations. However, with the increase of service varieties in 4G systems, more comprehensive billing and accounting systems are needed. The service provision process must interact dynamically with the charging process. The multitude of players in the 4th generation value chain and plethora of applications necessitates the need for some differentiated pricing and billing schemes. G. Mobility issues and Universal Roaming: Inter-system signaling and handover procedures, incorporation of user preferences, quality of service requirements of traffic flows, pricing information from higher layers in mobility management procedures. These requirements arise from the need to consider pricing information alongside with QoS levels in the decision stages of the service provision process. H. Security and Privacy: New security systems need to be developed when multiparty activities are involved in the new enterprise model for 4G networks. III. MAIN POLICY BASED ARCHITECTURE FOR SERVICE PROVISIONING IN 4G NETWORKS The growing interest in the field of Policy-Based Networking [3] to monitor and control the access rights of resources in large distributed systems, and in areas like Quality of Service (QoS), Wireless Networks [4], Network Security, Service Level Agreement (SLA) and IP address

allocation etc., signifies the dynamicity supported by the policy based approach. Hence Policy Based approach for service provisioning is ideal for 4G networks. A Service Level Agreement (SLA) [5] is a service contract between a customer and a service provider that specifies the forwarding service a customer should receive. SLA is a very static procedure that is done manually, whereas 4G wireless networks are dynamic to provide personalized and ubiquitous services to customers. Hence a policy-based approach to SLA is needed. Policy based architecture for 4G wireless network (See Figure 1) is structured into a layered abstraction. The lower layer forms the access networks in 4G communication systems. The IP end-to-end communication provider (IPe2eCP) provides basic IP connectivity. The service platform provider layer is like a packager [6] a business role that maintains customer relation. For Third Party Service Providers (3PSP’s) the service platform provider acts as a one-stop-shop for providing their services to End-users connected to and roaming between any possible access networks. End-users and corporate users can both be customers. SLA trading component (SLAT) is present in customers, service platform provider and IPe2eCP to negotiate service provisioning using the SLA Trading Algorithm given in Section 3. When two or more service agreements satisfy user preferences the policy server takes the decision by applying high-end policies as to select the best possible SLA. Whenever the mobile user desires to get connected to the access network, the user passes a unique identity to the service platform provider. The service platform provider has a policy server installed that embodies decision-making capabilities. The policy server with the aid of Authorization, Authentication and Accounting (AAA) server validate the user’s request. If the user is found to be an authenticated one and his request for service is an authorized one, the policy server fetches the appropriate policies for the user from the directory server through LDAP [7] and provides connectivity. Since 4G networks operate under heterogeneous access systems seamless mobility of users is seen as one of the key issues in resource and mobility management. Cost of service, availability of network resources, radio link quality and user preferences determine which system to use. SLA is traded between the service platform provider and IPe2eCP for performance metrics like bandwidth, delay, throughput, mobility factor etc., using the SLA Trading Algorithm given in Section 3 to provide best possible IP connectivity. Once connectivity is provided to users, the QoS levels are carefully monitored and tweaked to different operating levels (varying rate channel characteristics, bandwidth allocation, fault tolerance levels etc.) subjected to user preferences. For example, end-to-end signaling between application endpoints could be routed via UMTS, because of its predictable performance and quality of service guarantees, while the media stream is routed via a nearby WLAN to take advantage of its significantly greater bandwidth capacity. SLA is also

traded between the service platform provider and 3PSP’s, which will take up the role of current ISP’s [6] in the future. They perform functions like web hosting, email, virus scanning etc. Maximizing revenue and minimizing network usage levels whilst satisfying quality of service requirements for all traffic flows is the drive behind 4G wireless networks. The service provider platform thus acts as a value added communication provider that takes care of user profile management, QoS, personalization and customization of user services.

using their laptop may be willing to pay a premium price for the greater assurance levels the VPN service offers, while typical users browsing for content may be comfortable with a lower security level – and cost. Such differentiated pricing policies need to be effectively employed in 4G wireless networks. IV. SLA TRADING ALGORITHM FOR 4G NETWORKS Provisioning algorithm and Profitability Analysis algorithm [9], does not suit the framework as it takes into consideration very few performance metrics for trading. So, provisioning algorithm and Profitability Analysis algorithm with appropriate enhancements is proposed and given in Table 2. The constants used in Table 2 are given in Table 1. We call the algorithm responsible for the determination of what resources are needed. A passive provisioning algorithm does wait for requests from its customers to select which resources to buy. An active provisioning algorithm tries to forecast future needs. It will then buy resources in advance, before they become scarce. Buying in advance may be based on statistical information (e.g. previous weeks usage by time of day) or on trend analysis. Once an SLA trader knows it needs to buy some resource from one of its peers, it will have to select one of the bids and buy it. The selection of the bid is made based on the bid’s value for the SLA trader and its price. For bids of equal value, if no special policy is applied, the bid with the lower price will be selected. Table 1: Parameters for SLA algorithm

UPDATE_PERIOD volume () send bid()

Figure 1: Policy based architecture for 4G Wireless networks

The CAB module is responsible for the overall control of the charging process, providing advanced charging, accounting and billing services to different service providers and end users [10]. Customers may no longer belong to only one operator, but instead subscribe to many services from a number of service providers at the same time. It may be very inconvenient for a customer to deal with multiple service providers. Customers do not have to waste time handling all the financial transactions involved. The CAB collects charging information from both the network infrastructure and the Metering Devices (MDs), applies the appropriate pricing model based on policies for the particular user, calculates the portions that are due to each business entity, and produces a single itemized bill for each subscriber. Users can be segmented into the following categories: Gender, Age, Internet Usage, Income Brackets, and Mobile Professional [8]. Business users wishing to access corporate databases

accept bid() known dests MIN_REQUIREDBW

MAX_ALLOWED_DELAY

MAX_ ALLOWED_PL

MIN_ REQUIRED_BC

Time for updating volume function for an SLA object(time × bandwidth) sends an offered SLA to peer sends an accept message reachability list Minimum required bandwidth expressed in Mbps or in Kbps Maximum allowed delay expressed in unit of time such as seconds or in milliseconds Maximum allowed packet loss expressed as numeral representing the no. of packets Minimum required buffer capacity expressed as numeral repressing the number of packets.

MAX_ ALLOWED_QD

MIN_ REQUIRED_TP

MAX_ ALLOWED_JI

MAX_ ALLOWED_C

MAX_ ALLOWED _BC

MIN_ REQUIRED_MF

MAX_ ALLOWED_COST

Maximum allowed queuing delay expressed in unit of time such as seconds or in milliseconds Minimum required throughput expressed as numeral with each numeral representing throughput in the network Maximum allowed jitter expressed as numeral with each numeral representing jitter severity in the network Maximum allowed congestion factor expressed as numeral with each numeral representing congestion severity in the network Maximum allowed Battery Consumption expresses in terms of mw or in watts Minimum required mobility factor expressed in units of time such as minutes or hours Maximum allowed cost expressed in unit of currency such as rupees or in $

Table 2: SLA trading algorithm

struct bid { Host_dest, // Destination Host bw, // bandwidth delay, packet_loss, buffer_capacity, queuing_delay, throughput, jitter, congestion, battery_consumption, mobility_factor, cost } process trading () { while (true) { for each d in known_Host_dests { /* buy bids */ if(bw_to_Host(d)>MIN_REQUIREDBW) and (delay_to_Host(d)
(buffer_capacity_at_Host(d)>MIN_ REQUIRED_BC) and (queuing_delay_to_Host(d)MIN_ REQUIRED_TP) and (jitter_to_Host(d)MIN_MF) and (cost_to_Host(d)
Trading is done by the method ‘process trading()’ which finds the bid with the highest volume/cost ratio and finds out if that bid is profitable using the ‘is_profitable(bid)’ method and if found profitable accepts the bid using the ‘accept_bid(bid)’ method. Then for each neighbour (Hosts) if bid is not already sent then bid is sent for every UPDATE_PERIOD. The profitability is tested by comparing the bid price with the expected income. Bidding with the neighboring hosts is done using the ‘make_bid()’ method.

mainPanel.add("Center",Trader); window.setContentPane(mainPanel); window.pack(); window.setSize(200,100); window.setLocation(100,50); window.setVisible(true); //the code for SLA Trading Algorithm Given in section IV should be added here }// end of method execute

V. POLICY SPECIFICATION FOR SLA TRADING VI. POLICY SPECIFICATION FOR BILLING USERS The Policy Specification for the SLA trading is given in Table 3. The policy specification takes into account various performance metrics. // On a trading event the action trade sends a pop-up displaying that the trading is being analyzed to check if all the performance metrics constraints are satisfied with minimal cost.

The policy Specification for billing is given in Table 5. The policy specification takes into account various performance metrics. On a billing event the action billuser sends a pop-up displaying that the trading is being analyzed to check if all the performance metrics constraints are satisfied with minimal cost

Table 3: Policy specification for SLA trading

Table 5: Policy specification for billing users

inst oblig/Policies/TradingPolicy { on trading (host_name,required_bandwidth,battery_consumption, Mobility_factor,delay,battery_consumption, mobility_factor,s,congestion,queuing_delay, buffer_capacity,throughput); subject /PMAs/TradePMA; do trade(host_name,required_bandwidth,battery_consumpt ion,Mobility_factor,delay,battery_consumption,mobility _factor,congestion,queuing_delay,buffer_capacity throughput); } The rule /Policies/Trading Policy will invoke the action trade within the /PMAs/TradePMA’s engine, when the event trading is dispatched to the PMA from the trading event service. The corresponding java code, which enforces this policy, is given in Table 4.

inst oblig/Policies/BillingPolicy { on billing (user_ID,HomeOperator, serviceproviders[]); subject /PMAs/BillTradePMA; do billuser (user_ID,HomeOperator,serviceproviders[]); } The rule /Policies/Trading Policy will invoke the action billuser within the /PMAs/TradePMA’s engine, when the event billing is dispatched to the PMA from the billing event service. The corresponding java code, which enforces this policy, is given in Table 6.

Table 4: Java code for policy specification of SLA trading

public void execute(LinkedList params) throws Exception { // parameter0: The string representing the trade that will be considered // For debugging: if (DEBUG) { System.out.println("*******"); System.out.println("Trading the offer of : "+ (String) params.get(0)); } // Pop up the action window JFrame window = new JFrame(); window.setTitle("Trading Console"); JLabel traders = new JLabel("Trader: "+ (String) params.get(0)); JPanel mainPanel = new JPanel();

Table 6: Java code for policy specification of billing users

public void execute(LinkedList params) throws Exception { // parameter0: The string representing the trade that will be considered // For debugging: if (DEBUG) { System.out.println("*******"); System.out.println("Billing the offer of : "+ (String) params.get(0)); } // Pop up the action window JFrame window = new JFrame(); window.setTitle("Billing Console"); JLabel bill = new JLabel("Billing: "+ (String) params.get(0)); JPanel mainPanel = new JPanel(); mainPanel.add("Center",Billing); window.setContentPane(mainPanel); window.pack(); window.setSize(200,100); window.setLocation(100,50); window.setVisible(true); //the code for SLA Trading Algorithm Given in section IV should be added here }// end of method execute

VII. CONCLUSION This paper proposes Policy based architecture for efficient service provisioning in 4G wireless networks. SLA is traded between the service platform provider and different business entities in 4G wireless networks using the SLA Trading Algorithm. Applying the Policy Specifications, an effective SLA is drawn to meet user preferences. Thus the proposed framework benefits both the users and service providers. Users benefit from faster access to a range of multimedia services with reasonable QoS and lower cost. It allows service providers to rapidly develop customized and personalized services to gain competitive advantage. REFERENCES [1]

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