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Voice Over IP in Mobile Networks

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Voice Over IP in Mobile Networks Voice over IP in Mobile Networks Ludde Algell Department of Communication Systems Lund Institute of Technology 1 2 Executive Summary Title: Voice over IP in mobile networks. Author: Ludde Algell Tutor: Ulf Körner Objective: Voice over IP is rapidly transforming fixed line networks. The new technology slashes prices on telephony in an unprecedented manner. However it is not clear if Voice over IP will have the same effect on mobile telephony. The objective of this thesis is to determine if there are essential differences between fixed and wireless voice over IP and in which ways IP will affect mobile operators. Analysis: In order to determine how VoIP will affect mobile operators the following areas were investigated: • A background description of VoIP • The current market for fixed VoIP • Radio access technologies and VoIP • VoIP and new services in the mobile network Conclusions: Mobile operators are unlikely to, in the coming 3 years, experience the same type of competition from VoIP as fixed line operators are experiencing. The main reason is the bandwidth-limited radio interface that requires services, such as voice calls, to be highly optimized. At present VoIP is an inefficient way of delivering voice service. There will also be a lack of attractive VoIP handsets. Currently, VoIP calls made with VoIP applications are not substituting mobile calls. VoIP applications are mainly used for international calling. By offering subscribers the possibility to use VoIP applications over mobile broadband it should therefore be possible for a mobile operator to increase revenue, without cannibalizing on existing voice revenue. The threat from alternative access technologies like WiMAX and WiFi is not imminent for mobile operators’ voice revenue. Mobile operators with 3G networks could however see negative impact on mobile data revenue. WiFi network can be launched fast and at low cost. It is therefore recommendable for operator’s to implement a WiFi strategy. 3 4 Foreword This report is the result of a Masters thesis project at Millicom International Cellular and the Department of Communication Systems at Lund Institute of Technology. Thanks to Won-Suck Song at Millicom and Ulf Körner at the Department of Communication Systems. Also thanks for great support, ideas, and corrections from Thomas Beijar, Philip Henriksson and Anjna Mehta Ludde Algell Stockholm, December 18, 2005 5 6 1 Introduction............................................................................................................... 11 2 Introduction to IP Telephony .................................................................................... 13 2.1 Circuit switched networks .....................................................................................................13 2.2 Packet-switched networks......................................................................................................14 2.2.1 TCP/IP............................................................................................................................................... 15 2.2.2 RTP.................................................................................................................................................... 16 2.3 IP telephony protocols............................................................................................................16 2.3.1 Session Initiation Protocol ............................................................................................................... 17 2.3.2 H.323................................................................................................................................................. 17 2.4 Categories of VoIP ..................................................................................................................17 2.5 Speech Coding and Codecs....................................................................................................19 2.5.1 Codec negotiation in VoIP............................................................................................................... 19 2.5.2 Wideband codecs.............................................................................................................................. 20 2.5.3 Efficiency and Bandwidth................................................................................................................ 20 2.6 Header compression................................................................................................................22 2.6.1 Slow start and congestion control ................................................................................................... 22 2.6.2 Conext ............................................................................................................................................... 23 2.6.3 Robust Header Compression ........................................................................................................... 23 2.6.4 Performance improvements ............................................................................................................. 23 2.7 Measuring voice quality .........................................................................................................24 2.8 VoIP and Quality of Service ..................................................................................................25 2.8.1 Bandwidth ......................................................................................................................................... 25 2.8.2 Latency.............................................................................................................................................. 25 2.8.3 Jitter ................................................................................................................................................... 26 2.8.4 Reliability.......................................................................................................................................... 26 2.8.5 Reliability.......................................................................................................................................... 27 2.9 Provisioning QoS.....................................................................................................................27 2.9.1 IntServ or Flow Based Control........................................................................................................ 28 2.9.2 DiffServ............................................................................................................................................. 28 2.9.3 Smart routing .................................................................................................................................... 28 2.9.4 Blocking VoIP traffic by providing sub par quality....................................................................... 28 2.9.5 Comments ......................................................................................................................................... 29 7 3 Current market for fixed Voice over IP..................................................................... 30 3.1 Business fixed line VoIP .........................................................................................................30 3.2 Residential fixed line replacement VoIP .............................................................................31 3.3 Instant Messaging and Softphones .......................................................................................32 3.4 Major VoIP providers ............................................................................................................36 3.5 Future development ................................................................................................................37 3.6 Market Value ...........................................................................................................................38 3.7 Comments.................................................................................................................................38 4 Voice over IP over Wireless Channels....................................................................... 40 4.1 Basics of Radio Communication...........................................................................................40 4.1.1 Frequency, Power and Coverage:.................................................................................................... 40 4.1.2 Radio Resources and Cost ............................................................................................................... 42 4.1.3 Non Line of Sight Communication ................................................................................................. 43 4.1.4 System Capacity Improvements ...................................................................................................... 43 4.1.5 Bandwidth Limits ............................................................................................................................. 45 4.1.6 Evolution Radio................................................................................................................................ 45 4.1.7 Spectrum Licenses............................................................................................................................ 46 4.1.8 Spectrum Availability ...................................................................................................................... 46 4.1.9 Comments ........................................................................................................................................
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