making nets work CNS 1 Aviation Wireless Communications Chris Wargo Presented to IAB Workshop on Wireless Internetworking February 29 - March 2, 2000 Computer Networks & Software, Inc.

making nets work CNS 2 Agenda n Today's Aeronautical Telecommunication Network (ATN) n Potential of TCP/IP Architecture for Aviation n Mobility Management Requirements n Summary n Discussion

making nets work CNS 3 Wireless Application Categories (Voice and Data) n Air Traffic Management (ATM) –Air Traffic Control (ATC) –Air Traffic Services (ATS) –Communication, Navigation, & Surveillance (CNS) n Airline Operational Communications (AOC) –Flight Operations –Maintenance –Airport/Ramp Operations n Airline Administrative Communications (AAC) n Airline Passenger Communications (APC) n Entertainment

making nets work CNS 4 Global Customers of the Wireless Aviation Market Type Size Indication Commercial Aviation 15,000 Aircraft plus ( times # of passengers) Business Aviation 25,000 Aircraft plus General Aviation 100,000 Aircraft plus Cargo Aviation 10,000 Aircraft plus Military 50,000 Aircraft plus Government184 Countries of ICAO

making nets work CNS 5 Aeronautical Telecommunication (ATN) Network Environment ATN ROUTER Avionics SubnetworkMode S SubnetworkHF SubnetworkSatellite SubnetworkVHF Subnetwork CAA Ground Subnetwork Management Processor ATN End System Aeronautical Operations Data Base ATN End System Data Display Processor ATN End System Data Entry Processor ATN End System Management Processor ATN End System Aeronautical Operations Control ATN End System Weather Data Base ATN End System ATC ATN End System FIS Data Base ATN End System Weather Data Base ATN End System Service Provider Ground Subnetwork Airline Ground Subnetwork

making nets work CNS 6 Evolution of Aviation Wireless Communications PanAm Satcom Demo FANS Committee VDL Mode 2 CPDLC I&IA PETAL II & LINK 2000 ATN - ISO Definition GPS SATCOM (ATS,AOC,APC) CPDLC II & III NEXCOM VDL Mode 3 VDL Mode 4 CNS/ATM - FANS 1&A ACARS EACARS & AVPAC Attempts Passenger Telephone Systems HF Data Link ATN - IPv? Definition SATS

making nets work CNS 7 Consists of Applications and communication services that allow ground, air-ground, and avionics sub-networks to inter-operate End System(ES) Application Entity Upper Layer Communications Service Internet Communications Service Intermediate System (IS) Application Entity Upper Layer Communications Service Internet Communications Service Intermediate System (IS) Subnetwork End System(ES) ATN Architecture Context Management (CM) Application Automatic Dependent Surveillance (ADS) Controller Pilot Data Link Communication (CPDLC) Flight Information Service (FIS) ATS Message Handling Services (ATSMHS)

making nets work CNS 8 Aeronautical Communication Requirements n Interoperability with existing subnetworks n High availability n Mobile Communication n Message prioritization n Policy based routing n Security n Bit Efficiency n Support for multiple mobile subnetworks n Mobile platform forms its own Routing domain

making nets work CNS 9 Today’s ATN Status n ICAO - 91 Nations Agreement 1991 n Published Standards - SARPS Edition 3, end of 2000 n Several Cooperative Attempts - Stalled Out n FAA Funded Router Development - ATNS,Inc. n Limited ATN Router Availability n End System Applications under development n Wireless Components not yet “Red Label” n European, Eurocontrol lead early trials ongoing n FAA CPDLC I - Initial Operation 2002

making nets work CNS 10 Application Connection Oriented Session Protocol (COSP) Transport Layer (TP4) Network Layer (CLNP) Air-Ground Subnetwork Ground-Ground Subnetwork Application Service Element (ASE) Dialog Service (DS) Control Function (CF) Application Layer Application Transport Layer (TP4) Network Layer (CLNP) Air-Ground Subnetwork Ground-Ground Subnetwork ASE DS ACSE CF Fast Byte COPP and COSP ATN Protocol Architecture Connection Oriented Presentation Protocol (COPP) Sub Networks Association Control Service Element (ACSE) ISO Air-Ground Fast Byte approach selected to obtain bit efficiency over the Air-Ground Link

making nets work CNS 11 Transport Layer (TCP) Network Layer (IP) Air-Ground Subnetwork Ground-Ground Subnetwork ATN and TCP/IP Protocol Architecture Transport Layer (TP4) Network Layer (CLNP) Air-Ground Subnetwork Ground-Ground Subnetwork Application ASE DS ACSE CF Fast Byte COPP and COSP Application ATN Architecture TCP/IP Architecture With the Fast Byte enhancements, the two architectures appear similar in structure

making nets work CNS 12 TCP and TP4 Features Comparison Both support Connection-oriented and Connectionless Transport services Source: Aeronautical Related Applications Using ATN and TCP/IP Research Report, prepared by CNS for the NASA Glenn Research Center, November 23, 1999

making nets work CNS 13 IP and CLNP Features Comparison Both support Connectionless Network services Source: Aeronautical Related Applications Using ATN and TCP/IP Research Report, prepared by CNS for the NASA Glenn Research Center, November 23, 1999

making nets work CNS 14 IP and CLNP Features Comparison Source: Aeronautical Related Applications Using ATN and TCP/IP Research Report, prepared by CNS for the NASA Glenn Research Center, November 23, 1999

making nets work CNS 15 Challenge for the Aeronautical World Could TCP/IP protocol meet Aeronautical requirements? n Benefits: –Lower Infrastructure cost –Potential for new services: »VoIP »Multicast »Security »Integration with Public Infrastructure Challenges: n Modifying Political agreement/ Industry Standards n Addressing Technical Issues for: –Mobility Management –Policy based routing capability

making nets work CNS 16 Subnetworks Air-Ground (A/G): n Aeronautical Mobile Satellite n VHF Data Link n Mode S n HF Data link n Passenger Telephony Ground-Ground: n X.25 PSDNs n Frame Relay n LANs n Leased Lines n NADIN

making nets work CNS 17 Overview of VDL Modes Mode DataVoice VDL Mode 1Yes No VDL Mode 2 YesNo VDL Mode 3 Yes VDL Mode 4Yes No Characteristics Provide 4 logically independent channels in a 25kHz frequency assignment. Each channel can be allocated to voice or data. Uses differentially encoded 8-phase shift keying (D8PSK) at 31.5 kbps Standard media access control based on 4 slots structure Extended range uses 3 slot structure Uses Self-organizing Time division multiplexing (STDMA) Uses TDMA based short time slots Uses a reservation protocol to gain link access Data rate of 1200 bps Channel shared among all using aircraft Channel access based Carrier Sense Multiple Access (CSMA) Uses the same frequency band as Mode1, but uses better data encoding modem Differentially encoded 8-phase shift keying (D8PSK) with channel data rate of 31.5 kbps Channel access based Carrier Sense Multiple Access (CSMA)

making nets work CNS 18 Subnetworks Requirements n Byte and code independence n Address individual systems n Provide error detection –Undetected error better than 1 in 10 8 n Packet mode technology n Connectionless and Connection mode n Prioritization of data –Important for safety related data n QoS Management –Throughput and Transit delay guarantees n Mobile subnetworks –Ability to report aircraft joining the subnetwork –Ability identify aircraft leaving a subnetwork

making nets work CNS 19 Mobility and Roaming n Mobility between subnetworks while staying in contact –Supported by the data link layer n ATN must support Roaming between networks –Aircraft may move from one mobile subnetwork to another –Aircraft may be simultaneously attached to more than one mobile subnetwork

making nets work CNS 20 Mobile Routing Issues n Routes cannot be aggregated –Mobile addresses not related to topology n Route changes every time aircraft changes point of attachment –High rate of routing updates n Routers have to keep a route for each aircraft –ATN size limited by router table capacity

making nets work CNS 21 ATN Solutions for Mobility n Uses Inter Domain Routing Protocol (IDRP) for routing n Implements distributed IDRP directory using Boundary Intermediate Systems (BISs) n Two level directory –ATN Island concept consisting of backbone BISs –Home BISs concept n Scalability obtained by the two level structure n Resilience is provided by the distributed approach

making nets work CNS 22 ATN Island Routing Domain Confederation ATN TRD ATN Backbone RDC ATN TRD ATN ERD ATN Island RDC Mobile RD Another ATN Island

making nets work CNS 23 Mobile Routing Example RD1RD2 RD3 RD4 n RD1, RD2 and RD3 support air/ground data links and RD4 depends on the other three (3) for A/G communication. n Using IDRP RD1 and RD2 advertise a route to the aircraft and RD4 can choose one of the route based on Routing policy.

making nets work CNS 24 Mobile Routing Example n As the aircraft travels it may lose contact RD1, RD1 informs others using the route withdraw message. n RD4 now has one path to the aircraft through RD2 and thus routes all traffic through RD2. n Further along in the flight, the aircraft may come in contact with RD3. A data link is established and routing information is exchanged. RD3 then advertises a new route to the aircraft. n RD4 again has two routes to the aircraft and chooses a route based on local routing policy. The aircraft goes through a similar process to select a route.

making nets work CNS 25 ATN Mobile Protocol Requirements n Shall support wide variety of mobile communications networks including aeronautical mobile- satellite service (AMSS), VHF digital link (VDL), HF digital link and SSR Mode S. Shall be possible to communicate with airborne avionics in any part of the world. n Shall support wide range of Organizational and National polices, including the enforcing of restrictions on what types of traffic can pass over both ground and air/ground data links, and control over which air/ground data link types are used by which applications n BISs shall advertise routes to each other, where a route consists of the set of addresses which identifies the destinations reachable over the router, and information about the route's path including the Quality of Service and Security available over the route. n Shall support policy based routing that enables users to control external access to their communications resources, and to protect themselves from problems elsewhere in the internetwork. n The ATN, mobile “platforms” on board an aircraft shall form a Routing Domain and must include an ATN Router that is also a BIS. n Shall support a two level concept of default route providers (ATN Island and Home) for containing high rate of information flow, and also to avoid the problems of routing instability caused by a rapid turnover of routing information. n Mobile routing shall support the user requirement that the users can specify, on a per application basis, routing control requirements.

making nets work CNS 26 NASA System Testbed Configuration

making nets work CNS 27 Summary n Aviation’s use of TCP/IP could yield significant benefits. n Without a common solution for mobile routing, Aviation’s ISO oriented ATN will remain in place. n Adopting IDRP-like mechanisms for mobile IP versus a BGP-like approach is a step in Aviation’s direction.

making nets work CNS 28 Wireless Application Categories (Voice and Data) n Air Traffic Management (ATM) –Air Traffic Control (ATC) –Air Traffic Services (ATS) –Communication, Navigation, & Surveillance (CNS) n Airline Operational Communications (AOC) –Flight Operations –Maintenance –Airport/Ramp Operations n Airline Administrative Communications (AAC) n Airline Passenger Communications (APC) n Entertainment Mobile IP ?

making nets work CNS 29 Acronym List ATNAeronautical Telecommunication Network ACARSAircraft Communications Addressing and Reporting System ACSEAssociation Control Service Element AMSS Aeronautical Mobile-Satellite Service ASEApplication Service Element BISBoundary Intermediate System CFControl Function COPPConnection Oriented Presentation Protocol COSPConnection Oriented Session Protocol CPDLCController-Pilot Data Link Communications DS Dialogue Service ERDEnd Routing Domain ICAOInternational Civil Aviation Organization FANSFuture Air Navigation System IDRP Inter Domain Routing Protocol NADINNorth American Digital Information Network (FAA) PETALPreliminary European Test of Air/Ground Data Link RDRouting Domain RDCRouting Domain Confederation TRDTransit Routing Domain VDL VHF Digital Link

making nets work CNS 30 Industry Initiatives n ATN –Context Management (CM) Application –Automatic Dependent Surveillance (ADS) –Controller Pilot Data Link Communication (CPDLC) –Flight Information Service (FIS) –ATS Message Handling Services (ATSMHS)

making nets work CNS 31 Air Traffic Management (ATM) n Predeparture Clearance n Taxi Clearance n Context Management n Controller to Pilot Data Link Communication n Automatic Dependent Surveillance n Waypoint Position Reporting n Emergency Messages n Future Air Navigation System n Oceanic Clearance n Future Free Flight n Flight Information Services n Airport Terminal Information Service n Digital Airport Terminal Information Service n Flight Information Services Broadcast n Notice to Airmen n METAR n Terminal Weather Information to Pilots n Local Area Augmentation System n Wide Area Augmentation System n Cockpit Voice (ATC)

making nets work CNS 32 AOC, AAC, APC and Entertainment Data Link Related System Control, Peripherals, and Subsystems (6 Applications/61 Formats) Flight Operations (14 Applications/30 Formats) Maintenance Operations (6 Applications) Airport/Ramp Area Operations Cockpit Voice Operations (Company ) Airline Administrative Communications (AAC) Airline Operational Communications (AOC) Airlines Gate Connections Medical Assistance Requests Crew Schedule and Lodging Information Miscellaneous Freetext Crew Information Future Applications – Passenger Handling Telephony Internet Services Facsimile Airline Passenger Communications (APC) Entertainment Games Movies/Videos Gambling Shopping Automated Teller Machines