1Evolution, Organization and StandardsNetwork Evolution, Standards, and Layered Architectures #22Evolution, Organization and StandardsOutline Network Evolution What makes communication systems work? How the network evolved?  How network provided more services for less cost? Predict where technology is going.  Standards  Organization Objectives Standards Organizations Layered Architectures OSI reference (layered) model TCP/IP network architecture (layered) model Goal: Understand how networks are described3Evolution, Organization and Standards(1)INVITE sip: [email protected]= IN IPv4 192.168.12.5m=audio 35092 RTP/AVP 0INVITE sip: [email protected]= IN IPv4 192.168.12.5m=audio 35092 RTP/AVP 0(2) (3)(4)(5) ringing(6)SIP/2.0 200 OKSIP/2.0 200 OK(7)ACK(8)Media flow(9)proxyregistrarElements of Current Communication Paradigm Session Initiation Protocol (SIP) for Voice over IP (VoIP)Modified From: Communication Networks: Fundamentals Concepts and Key ArchitecturesAuthors: A. Leon-Garcia and I. Widjaja4Evolution, Organization and StandardsElements of a Communications SystemTransmission Switching/Routing Signaling5Evolution, Organization and StandardsTimeEvolution of TransmissionAccess Technology• Twisted pair copper• Coax• Wireless• Others Powerline Satellite6Evolution, Organization and StandardsTransmission Network Resources Time When and how long a user gets to talk Frequency What part of the spectrum (channel) is used What “code” is used.7Evolution, Organization and StandardsTDMTime Division MultiplexingTime FDMFrequency Division Multiplexing**Modified from: Computer Networks, A. S. Tannenbaum, 4thEd, Prentice Hall, 2003Normally, users are not directly involved in resource allocationTransmission Network ResourcesTypical for analog voice8Evolution, Organization and StandardsFDMA and TDMA:Multiple Access (MA) is a channel access method; allowing several users to share the resource in time or frequency. The users transmit in “order”, each using his own frequency channel/time slot. FDMA= Frequency Division Multiple AccessfrequencytimeTDMA= Time Division Multiple Accessfrequency4 usersExample:Modified from: Computer Networking: A Top Down Approach Featuring the Internet, 2nd edition. Jim Kurose, Keith RossAddison-Wesley, July 2002.timeChannelTimeSlotFrameNormally, in MA networks users are directly involved in resource allocation9Evolution, Organization and StandardsSpectrogram of Downlink Physical Channel for Long Term Evolution (LTE)From: Peter Cain, Using Wireless Signal Decoding to Verify LTE Radio signals, Agilent Technologies, July 2011 Frequency Time 10 ms20 MhzTransmission Network Resources10Evolution, Organization and Standards Code Division Multiple Access (CDMA) Assume three users share same medium in time and frequency Users are synchronized & use different 4-bit orthogonal codes: {-1,-1,-1,-1}, {-1, +1,-1,+1}, {-1,-1,+1,+1}, {-1,+1,+1,-1}Section 6.4.3CodeBit timeBit timeModified From: Communication Networks: Fundamentals Concepts and Key Architectures Authors: A. Leon Garcia and I. WidjajaTransmission Network Resources11Evolution, Organization and Standards Downlink, e.g. , base station  smartphone Uplink, e.g., smartphone  base station Frequency-division duplexing (FDD) Downlink on frequency carrier 1, f1 Uplink on frequency carrier 2, f2 Time-division Duplexing (TDD) Downlink is time slots 1, k Uplink in time slots k+1, MTransmission Network Resources12Evolution, Organization and StandardsFrom: Agilent, 3GPP Long Term Evolution:System Overview, Product Development, and Test Challenges, Application NoteLTE Operating Bands: 15 use FDD and 8 use TDDTDD: Same Band for:BSUE & UE  BSLTE definitionsUE = User Equipment, e.g., smartphoneeNB = Evolved NodeB=Base station13Evolution, Organization and StandardsSwitching Manual Step-by-step Crossbar with stored program control Digital Switching Packet Switching Optical Switching14Evolution, Organization and StandardsStep-by-Step Switch15Evolution, Organization and StandardsStored Program Control System16Evolution, Organization and StandardsCrossbar Switch17Evolution, Organization and StandardsDigital Switching18Evolution, Organization and StandardsPacket Switching (Statistical Multiplexing) Packet switching provides flexibility and the dynamic allocation of bandwidth The Internet is a packet switched network Packet switching is leading to the integration of all services on one infrastructure: One infrastructure for voice, data, video Examples: VoIP and Video over IP (over the top)ArrivingPacketsBuffer(Queue)Server (b/s)DepartingPackets19Evolution, Organization and StandardsOptical Switching All current switches are electronic Current switches require photon-to-electron conversions (optical to electronic (E/O)) interfaces Optical switching will eliminate these interfaces Faster Cheaper Lower power required20Evolution, Organization and StandardsSignaling Signaling/Control: Governs network elements, e.g., telephone switches or packet switches (routers) Sets-up a communications capability  Maintains a communications capability  Ends (tears down) a communications capability  The signaling network carries the messages that controls the network elements Pulses  In the same transmission path as voice signal Tones  In the same transmission path as voice signal Computer Messages  Outside of the transmission path.– Common Channel interoffice signaling (CCIS)– Signaling System #7, (SS7)– Session Initiation Protocol (SIP) for VoIP – H.323– Others….. IP routing protocol messages, packets sent between processors that control IP routers21Evolution, Organization and Standards22Evolution, Organization and StandardsSurvivability  FIBER CUT  Jan., 4, 1991 - New York metro area – 6 million homes without long-distance service – New York Mercantile Exchange and New York Commodity Exchange shut down – Fiber cuts are common Survivability - SS7 FAILURE  June, 10, 1991 - California 2 million homes without phone service  June, 26, 1991 – Baltimore-10 million homes in 4 states without service & U.S. government phones affected  Survivability-SWITCH and POWER FAILURE  September, 17, 1991 - New York metro area – 2 million homes without long-distance service – 3 major New York airports close