Ph.D. Thesis titled Next Generation Telecom Network Optimization Submitted in partial fulfilment for award of the degree of Doctor of Philosophy (Electronics and Telecommunication Engineering) By Munir Bashir Sayyad (Reg. No. : 20090304) Research Guide Dr. S. L. Nalbalwar Department of Electronics and Telecommunication Engineering Dr. Babasaheb Ambedkar Technological University Lonere 402 103, Dist. Raighad [M.S.] (August 2013)
In the loving memory of My Late father Abbu, and dedicated to My Mother Ammi, Wife Faimida, Sweet Daughter Alfiya and Loving Son Arslaan. i
Contents Contents List of Figures List of Tables Acknoledgement Declaration of Candidate Acronyms Abstract II VIII X XI XIII XIV XVII 1. Introduction 1 1.1 NGTN architecture 2 1.1.1 Transport functions 3 1.1.2 Transport functions activities 4 1.1.3 Control functions 4 1.1.4 Service functions 5 1.2 Motivation for NGTN Optimization 5 1.2.1 To achieve High bandwidth with access agnostic philosophy 5 1.2.2 To achieve Bandwidth Optimization and QoS enablement 5 1.2.3 Audio, Video Quality Improvements 5 1.3 Problem Statement 6 1.4 Aim 7 1.5 Importance of Next Generation Telecom Networks 7 1.6 Importance of Optimization in Telecom Networks 8 1.7 Importance of the Problem Statement & NGTN Capabilities 9 1.8 Objectives 10 1.9 Research Methodology 11 1.10 Fundamental Characteristics of NGTN 11 1.11 Contributions towards the Thesis 12 1.11.1 First Contribution: Proposed Network Architecture for NGTN 12 1.11.2 Second Contribution: Proposed Method for Network Behaviour optimization 13 1.11.3 Third Contribution: Application Destination Path Based Routing Optimization 15 1.11.4 Fourth ContributionTo provide Signalling Bandwidth Optimization: 16 1.11.5 Fifth Contribution: Using Network Intelligence for Bandwidth Optimization 17 1.11.6 Sixth Contribution: Video Traffic Optimization (Delay Elimination) 18 1.11.7 Seventh Contribution: Proposed Lawful Interception Monitoring System for NGTN 18 1.12 Novelty of the Idea 19 1.12.1 End-to-End Quality of Service 19 1.12.2 Network Management 20 1.12.3 Security Management 20 1.12.4 Generalized mobility 20 1.12.5 Disaster and relief communications capabilities 21 1.13 Organization of Thesis 21 ii
2. Literature Review 25 2.1 History of Next Generation Telecom Technology 25 2.1.1 Standardization Historical Background for NGN from Literature 25 2.1.2 Background History of ITU-T s Work on Next Generation Network 27 2.1.3 At Present 2005 to 2013: NGN Global Standards Initiative (NGN-GSI) 27 2.1.4 Evolution of Telecom Networks to Next Generation Telecom Networks 27 2.1.5 3GPP Work History on NGN IP Multimedia Subsystem 28 2.1.6 Global Status of NGN from Literature Survey 29 2.1.7 Literature review related to Next Generation Services 30 2.1.8 Literature review related to Next Generation Network Optimization 32 2.1.9 Conclusion 40 3. Next Generation Telecom Networks 41 3.1 Legacy and present day telecom networks 42 3.1.1 Public Switched Telephone Network (PSTN) 42 3.1.2 Speech Coding for PSTN 42 3.1.3 Mobile Networks 45 3.1.4 Wireless Cellular Networks 46 3.1.5 GSM 46 3.1.6 GPRS 48 3.1.7 CDMA Cellular Networks 48 3.1.8 UMTS Architecture 50 3.1.9 3G Technology 53 3.2 Basic Theory, principle and Importance: Next Generation Telecom Network 56 3.2.1 Basic Theory of NGN? 56 3.2.2 ITU-T definition of NGN (Feb 2004) 56 3.2.3 NGTN principles 57 3.2.4 Importance of NGTN 58 3.2.5 Present Day Network Realities 59 3.3 Evolution towards Next Generation Telecom Networks 60 3.4 Functional Network Nodes in LTE (4G) for NGTN 61 3.4.1 E-UTRAN: LTE Access Network 62 3.4.2 E-UTRAN Functions 62 3.4.3 EPC: LTE Core Network 64 3.4.4 MME 65 3.4.5 S-GW 65 3.4.6 P-GW 66 3.4.7 HSS 66 3.4.8 PCRF 66 3.5 Functional Network Elements of the Converged Core (IMS) 67 3.5.1 Session Border Controller (SBC 67 3.5.2 Interconnect border control function 69 3.5.3 Transport Gateway (TrGW) 70 3.5.4 Proxy- CSCF (P-CSCF) 71 iii
3.5.5 Emergency-CSCF (E-CSCF) 72 3.5.6 Location Retrieval Function (LRF) 73 3.5.7 Interrogating-CSCF 73 3.5.8 Serving-CSCF (S-CSCF 75 3.6 Interworking nodes (with other IP networks and other Legacy networks) 77 3.6.1 Breakout Gateway Control Function (BGCF) 77 3.6.2 Media Gateway Control Function (MGCF) 78 3.6.3 Media Gateway (MGW) 78 3.6.4 Signalling Gateway (SGW) 79 3.7 Application Nodes 80 3.7.1 MMTel/TAS 80 3.7.2 Group Calling Service (GCS) 81 3.7.3 Media Resource Function 82 3.7.4 Media Resource Function Controller (MRFC) 83 3.7.5 Media Resource Function Processor (MRFP) 83 3.8 Subscriber Data Repository Servers 84 3.8.1 Home Subscriber Server (HSS) 84 3.9 Service Delivery Platform (SDP) 85 3.9.1 IP Short Message Gateway (IP SMGW) 85 3.9.2 Notification Server 87 3.9.3 Cloud Address Book (CAB) 89 3.9.4 Social Networking Gateway (SNGW) 89 3.9.5 Rich Communication Suite Enhanced (RCSe) 91 3.9.6 Restful API 93 3.10 Charging Servers 94 3.10.1 Off Line Charging Server (OFCS) 94 3.10.2 On-Line Charging Server (OCS) 94 3.11 Support Elements 94 3.11.1 Load Balancer 94 3.11.2 Domain Name Server 95 3.11.3 ENUM Server 99 3.11.4 DRA 100 3.11.5 NTP 101 3.11.6 Number Portability Database (NPDB) 103 3.11.7 IMS generic architecture 103 3.11.8 Service or application plane 104 3.11.9 The control plane 104 3.11.10 User / Transport plane 105 3.11.11 IMS framework 106 3.11.12 IMS Logical Architecture 107 3.11.13 IMS Application Services 108 3.11.14 MMTel Service 109 3.11.15 Communication hold 110 3.11.16 Communication Barring 110 3.11.17 Communication waiting (CW) 111 iv
3.11.18 CRBT Services 111 3.11.19 Announcement Service 111 3.11.20 Advertise Service 111 3.11.21 Message and call tagging 112 3.11.22 Notification Services 112 3.11.23 Cloud Services 114 3.11.24 Messaging Services 115 3.11.25 IPSM (IP shot message) Gateway 116 3.11.26 Social Networking 116 3.12 Conclusion 117 4. Optimization of the Next Generation Telecom network 118 4.1 Proposed Network Elements for Next Generation Telecom Network Architecture 119 4.1.1 Session Control Network Nodes 120 4.1.2 Media Gateway Control Function (MGCF) 120 4.1.3 Interworking nodes (with other IP networks and other Legacy networks) 120 4.1.4 Application Nodes 121 4.1.5 Subscriber Data Repository Servers 121 4.1.6 Service Delivery Platform (SDP) 121 4.1.7 Charging Servers 122 4.1.8 Support Network Elements 122 4.1.9 Advantages of the Proposed Architecture of NGTN 122 4.2 Analysis of Different Methods of Congestion Control in SS 7 Network 124 4.2.1 Introduction to Packet Switched network and SS7 Signaling mechanism 124 4.2.2 Signaling Network Nodes 125 4.2.3 Introduction to Congestion Control 127 4.2.4 MTP Routing and Congestion Control 128 4.2.5 MTP Congestion Control 130 4.2.6 SCCP Routing and Congestion Control 132 4.2.7 Conclusion on SS7 Congestion Control 133 4.3 A Novel Method for bandwidth optimization on retransmitted in SIP 133 4.3.1 Introduction to SIP (Session Initiation Protocol) 134 4.3.2 Mathematical Modelling 140 4.3.3 Bandwidth Optimization result discussion and conclusion 142 4.4 Improvement and optimization of QoS of a Multiple Server Queue 143 4.4.1 Introduction to Server queuing Models 143 4.4.2 Single Server Queue 144 4.5 Multi Server Queue 145 4.5.1 Discussion on LITTLE s Law 147 4.5.2 Use of LITTLE s Law for MSMA 148 4.5.3 Discussion on Results and Conclusion 150 4.5.4 Results 150 4.6 Resolving Network Security Issues in IP-PBX in Converged Architecture 151 4.6.1 Introduction to IP PBX (Internet Protocol Private Branch Exchange) 151 v
4.6.2 IP PBX Overview 152 4.6.3 IP-PBX System Architecture 153 4.6.4 Network Security Issues 154 4.6.5 Prevention of Security Violation 155 4.7 Result Discussion 156 4.8 Proposed Method for Network Behaviour optimization 156 4.9 Application Destination Path Based Routing Optimization for NGTN 159 4.10 Using Network Intelligence for Bandwidth Optimization 161 4.10.1 Experimental setup and Conclusion 163 4.11 Video Traffic Optimization (Delay Elimination) 164 4.12 Conclusion 167 5. Lawful Interception Monitoring Optimization using Distributed Architecture 168 5.1 Next Generation Telecom Network Complexity for LI 170 5.2 Proposed Distributed Architecture for Lawful Interception 172 5.3 What happens during LI of SIP to H323 call? 174 5.4 Call Flow Steps of Proposed LI 175 5.5 Conclusion 178 6. Core Network System Optimization Results 179 6.1.1 Objective: - Open Source OS optimization is focused on the following activities 180 6.2 Technical Discussion and Implementation 181 6.2.1 Initial Environment 181 6.2.2 HSS (Home Subscriber Server) 181 6.2.3 HSS Architecture 181 6.2.5 Desired Performance Metrics 182 6.2.5 HSS Tuning and Optimization 182 6.2.7 Error Detection and Correction (EDAC) units 183 6.2.7 Power Management 183 6.2.8 System Management Interrupts (SMI) 183 6.3 SOFTWARE TUNING 183 6.3.1 HSS Core Build Design & OS Tuning 183 6.3.2 HSS Post Iteration 1 184 6.3.3 PCSCF (IMS) 184 6.3.4 PCSCF Architecture 185 6.3.5 Desired Performance Metrics 185 6.3.6 PCSCF Performance Tuning (ITERATION 1) 185 6.3.7 Power Management 186 6.3.8 Error Detection and Correction (EDAC) units 186 6.3.9 System Management Interrupts (SMI) 187 6.3.10 Observations 187 6.4 Software Tuning 187 6.4.1 PCSCF Core Build Design & OS Tuning 187 6.4.2 PCSCF Post Iteration 1 Tuning and Performance Optimization 188 vi
6.4.3 Objective 188 6.4.4 Experimental set up preparation 188 6.4.5 Overall IMS Optimization Test Results 190 6.4.6 Conclusion 190 7. Conclusion 191 7.1 Objectives achieved 191 7.2 Future Scope 193 Bibliography 195 Published Papers 203 vii
List of Figures Figure 1.1: NGTN Decomposition Layer... 2 Figure 1.2: NGTN Transport Layer... 4 Figure 1.3: NGTN control layer... 4 Figure 1.4: NGTN Proposed Architecture... 13 Figure 1.5: Thesis Organization... 21 Figure 3.1 : GSM system architecture... 47 Figure 3.2 : UMTS architecture... 52 Figure 3.3 : Evolution towards NGTN... 55 Figure 3.4 : NGTN uses... 58 Figure 3.5 : Migration towards NGTN... 61 Figure 3.6 : Overall LTE Architecture... 62 Figure 3.7: Overall E-UTRAN Architecture... 64 Figure 3.8: SBC Interfaces... 69 Figure 3.9: Interfaces of the P-CSCF... 71 Figure 3.10: E-CSCF Interfaces... 73 Figure 3.11: I-CSCF interfaces... 75 Figure 3.12: S-CSCF interfaces... 76 Figure 3.13: BGCF interfaces... 78 Figure 3.14: Media Gateway Interfaces... 79 Figure 3.15: Media Gateway Architecture... 80 Figure 3.16: MMTel/TAS Interfaces... 81 Figure 3.17: GCS Interfaces... 81 Figure 3.18: MRF Interfaces... 82 Figure 3.19: HSS Interfaces... 85 Figure 3.20 : Architecture of the IP SMGW... 86 Figure 3.21: IP SMGW interfaces... 87 Figure 3.22: Architecture of Notification Server... 88 Figure 3.23: NS interfaces... 89 Figure 3.24: CAB Interfaces... 89 Figure 3.25: SNGW Architecture... 90 Figure 3.26: SNGW Interfaces... 91 Figure 3.27: RCSe Architecture... 91 Figure 3.28: RCSe Interfaces... 92 Figure 3.29: DNS Hierarchy... 96 Figure 3.30: DNS Procedure... 97 Figure 3.31: ENUM Mapping... 99 Figure 3.32: ENUM call flow... 100 Figure 3.33: DRA Routing Interfaces... 101 Figure 3.34: NTP Logical architecture... 102 Figure 3.35: IMS architecture... 106 Figure 3.36: IMS framework... 107 Figure 3.37: IMS logical architecture... 107 viii
Figure 3.38: IMS Services... 108 Figure 3.39: Service Flow Diagram... 117 Figure 4.1 : NGTN Proposed Architecture... 119 Figure 4.2 : Single Level Hierarchy... 126 Figure 4.3: Two Level Hierarchies... 127 Figure 4.4 : Failed STP condition... 131 Figure 4.5 : Registration process.... 136 Figure 4.6 : Proxy server example... 137 Figure 4.7 : Request redirection.... 138 Figure 4.8 : SIP Session setup... 140 Figure 4.9 : Message length versus message flow... 143 Figure 4.10 : Components of a Basic Queuing Process... 144 Figure 4.11 : Single Server Queue... 145 Figure 4.12 : Little s Law Representation... 148 Figure 4.13 : Practical set up of Interfacing IP-PBX with MSC through SBC... 153 Figure 4.14 : SIP call flow for a call originated from IP- PBX and terminating on cell phone... 154 Figure 4.15 : A part of SIP invite message (611)... 154 Figure 4.16 : IP-PBX server as a separate network element for managing IP-PBXs... 156 Figure 4.17 : Traffic Characteristics per AS Path... 160 Figure 4.18 : Use of Network intelligence for Bandwidth optimization... 162 Figure 4.19 : Video traffic optimization setup... 164 Figure 5.1 : NGN layered structure... 171 Figure 5.2 : Distributed architecture diagram... 173 Figure 5.3 : SIP to H323 call Setup... 174 Figure 5.4 : Call flow for LI during SIP to H323 call... 176 Figure 6.1 : IMS Test Setup... 180 Figure 6.2: HSS Schematic... 182 Figure 6.3 : PCSCF Schematic... 186 Figure 6.4 : Experimental setup flow for kickstart... 189 ix
List of Tables Table 3.1 : Tandem Coding Performance of Some PSTN Narrowband Codecs... 43 Table 3.2 Tandem Coding Performance of Some PSTN Narrowband Codecs... 44 Table 3.3 : Characteristics of Wideband Speech Coding Standards for PSTN... 45 Table 3.4 : 3G Characteristics... 53 Table 4.1 : Session Control Functions... 120 Table 4.2 :Media Gateway Functions... 120 Table 4.3 : Interworking Nodes... 120 Table 4.4 : Application Nodes... 121 Table 4.5 : SDR Servers... 121 Table 4.6 : SDP Servers... 121 Table 4.7 : Support Network Elements... 122 Table 4.8 : Mapping table at MSC end... 155 Table 4.9 : Video Call packet analysis... 166 Table 6.1 : Hardware tuning HSS... 182 Table 6.2 : Tuning and Performance Data... 184 Table 6.3: Hardware tuning - PCSCF... 185 Table 6.4 : Tuning and performance optimization PCSCF... 188 x
Acknowledgements The endless thanks goes to Lord Almighty for all the blessings he has showered upon me. During the period of my research I have been blessed with some extraordinary people who have spun a web of support around me. Words can never be enough in expressing how grateful I am to those incredible people in my life who made this thesis possible. I am deeply indebted to my research supervisor, Professor Dr. Sanjay Nalbalwar for presenting me such an interesting thesis topic. Each meeting with him added invaluable aspects to the implementation and broadened my perspective. He has guided me with his suggestions, lightened up the way in my darkest times and encouraged me a lot in the academic life. From him I have learned to think critically, to select problems, to solve them and to present their solutions. I would like to thank him for furthering my education in many subjects like probability theory, Computer network, Telecom networks and Multirate Signal Processing. His drive for scientific excellence encouraged me to go for research in the latest research area of my interest. Sometime we are just (or incredibly) lucky!!! To get such wonderful, inspiring and motivating Guide. It was a great pleasure for me to have a chance of working with him. I consider it a great honour to have been part of Rancore lab, and I salute the efforts of my Mentor Mr. P.K. Bhatnagar for his contributions towards furthering the cause of Indian innovations in Telecommunication world. He has always been an inspiration and source of motivation for me to continue striving for research and keep learning. I would like to thank Mr. K. T. Subramanian for His invaluable support and guidance. Subramanian Sir has given me confidence and encouraged me xi
to continue the research work. My deep gratitude towards Prof. G. R Sreenivasan for his support and encouragement. I would also like to thank Mr. Kuppu Sridhar for His valuable suggestions and all the technical discussions. I would like to convey my gratitude to Prof. Dr. S.B. Deaosarkar for His precious inputs and suggestions. It is with sincere gratitude that I wish to thank Dr. Milind Pandey, Dr. J.W.Bakal, Dr.Sandeep Inamdar, for being particularly supportive during times of need. I take this opportunity to dedicate this work to my parents who have made me what I am, wife and children who have given consistent support throughout my research, and my guide who have shown faith in my work and enthusiasm. I will be failing in my duty if I don t acknowledge some of my friends who had helped me to continue my research work. I would like to thank Mr. Aayush Bhatnagar for giving insight of many telecom protocols in IMS. I would like to mention my sincere thanks to Mr. Atul Agrawal and Mr. Amrish Bansal for their Support and co-operation. I would like to mention my special thanks to Mr. Anup Patil for his invaluable inputs, critique and long discussions on the research topic. His quality of deep diving in to the subject has motivated me a lot. My sincere thanks to Prof. Shankar Nawale for his support and encouragement during the research. There are so many known or unknown individuals, who have helped me directly or indirectly in this period. It is impossible to name each and every one. My sincere thanks to all of them. Munir Bashir Sayyad xii
Declaration by the Candidate I hereby declare that the work being submitted in this thesis titled Next Generation Telecom Network Optimization in partial fulfilment for the requirements for the award of degree of Doctor of Philosophy and submitted in the Department of Electronics & Telecommunication Engineering, Dr. Babasaheb Ambedkar Technological University, Lonere-Raigad, is an authentic record of my own work carried out during the period from 4 th July 2009 to 20 th July 2013 under supervision of Prof. Dr. Sanjay L. Nalbalwar (Head of the Department of Electronics & Telecommunication Engineering, DBATU, Lonere). The matter presented in this thesis has not been submitted for award of any other degree of this or any other University /Institute. Munir Bashir Sayyad Name of the Candidate: Munir Bashir Sayyad Registration No.: 20090304 This is to certify that the above declaration made by the candidate is correct to the best of my/our knowledge and belief. Dr. S.L Nalbalwar (Supervisor) xiii
Acronyms AKA AS BG Authentication and Key Agreement Application Server Border Gateway BGCF Breakout Gateway Control Function CDR CS Charging Data Record Circuit Switched CSCF Call Session Control Function CSR Cell Site Router DHCP Dynamic Host Configuration Protocol DNS DRA Domain Name System Diameter Routing Agent ENUM E.164 Number Mapping GMLC Gateway Mobile Location Centre HSS IBCF Home Subscriber Server Interconnection Border Control Function I-CSCF Interrogating-CSCF IETF IMS IMSI IN IP Internet Engineering Task Force IP Multimedia Core Network Subsystem International Mobile Subscriber Identifier Intelligent Network Internet Protocol IPv4 Internet Protocol version 4 IPv6 Internet Protocol version 6 IP-SM-GW IP Short Message Gateway ISDN ISIM Integrated Services Digital Network IMS SIM xiv
ISUP ISDN User Part IWF Interworking Function MGCF Media Gateway Control Function MME Mobility Management Entity MRFC Multimedia Resource Function Controller MRFP Multimedia Resource Function Processor NAI Network Access Identifier NAPT Network Address Port Translation NAT Network Address Translation NA(P)T-PT Network Address (Port-Multiplexing) Translation-Protocol Translation NPDB Number Portability Database NTP OCS Network Terminal Point Online Charging System OFCS Offline Charging System OIP OIR Originating Identification Presentation Originating Identification Restriction P-CSCF Proxy-CSCF PCC Policy and Charging Control PCEF Policy and Charging Enforcement Function PCRF Policy and Charging Rules Function PDN PDP Packet Data Network Packet Data Protocol e.g., IP PLMN Public Land Mobile Network PSI Public Service Identity PSTN Public Switched Telephone Network PSAP Public Safety Answering Point QoS RFC Quality of Service Request for Comments xv
SAEGW SAE Gateway SCS Service Capability Server S-CSCF Serving-CSCF SDP SLF SSF Session Description Protocol Subscription Locator Function Service Switching Function SS7 Signalling System 7 SIM SIP Subscriber Identity Module Session Initiation Protocol S-GW Signalling Gateway THIG Topology Hiding Inter-network Gateway TIP TIR Terminating Identification Presentation Terminating Identification Restriction TrGW Transition Gateway xvi
Abstract The emergence of convergence created a need to articulate altogether different telecommunication architecture. Application Convergence, Services Convergence and Network Convergence are to be considered while preparing the converged network architecture. The Legacy network architecture does not support multiple services and functions which are becoming necessary today (Voice, Video and Data etc.). At the same time internet architecture is evolving to provide some blended converged services but do not comply with telephony service architecture and regulations. The telecommunication technologies evolution was planned by many standardization bodies across the world like 3GPP, 3GPP2, ETSI, ARIB etc. Each one of them has proposed different ways and means to get high throughput at the user end with various methods. Also the methods vary on the basis of services provided at user end. But the concept of convergence and planning of providing all services like voice, video and data at user end gives rise to various possibilities and many technical challenges as well. The presented research work focuses on the problems of converged architecture of Next Generation Telecommunication Network. This work focuses on End to End Network optimization in particular. As the Next Generation Telecommunication Network will be completely heterogeneous in nature and a different approach is required for its optimization. The research work also incorporates the access agnostic IP Multimedia Subsystem in NGTN. The use of IMS also creates multiple possibilities to optimise the network. This becomes a special case of NGTN optimisation as well. The test setup of open source IMS was created to realise various scenarios. Novel method of Lawful Interception Monitoring is proposed to provide adequate security and comply the NGTN with regulatory procedures. Attempt is made to optimise end to end Next Generation Telecommunication Network by taking 360 degree view of the network. RF optimization, Backhaul optimization, Core Network and System Optimization methods are generalised. Use of network intelligence is done as much as possible to make adaptive optimization reality in heterogeneous network environment. While thinking of next generation xvii
telecommunication network special consideration is given to keep legacy network functioning intact. Bandwidth Consumption aware and call status aware type of optimization methods are introduced in the Network for Self-healing of the network. Traffic segregation at system end and deep packet classification at network end are the concepts introduced for network optimization. Network Optimization performance matrix is prepared along with the predefined KPI s and drills down work flow analysis structure is proposed for effective manageability of the NGTN. Thus the thesis is concluded and dedicated for end to End Optimization of NGTN. xviii
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