Surface CNS Network Data Requirements Study Summary



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International Civil Aviation Organization

WORKING PAPER |ACP-WGF15/WP26

26/05/06

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AERONAUTICAL COMMUNICATIONS PANEL (ACP)

FOURTEENTH MEETING OF WORKING GROUP F

Cairo, Egypt 7 – 13 June 2006

|Agenda Item 5: |AM(R)S spectrum requirements (Future Communications System (FCS)) |

Surface CNS Network Data Requirements Study Summary

(Presented by Robert Kerczewski, NASA Glenn Research Center)

|SUMMARY |

|In 2004, the Science Applications International Corporation (SAIC – formerly Trios Associates, Inc.) was |

|funded by the NASA Glenn Research Center to characterize the current and expected airport surface data |

|requirements. This effort aimed at developing high level operational requirements for an airport wireless|

|surface network. This report presents the executive summary of a full report, presenting the results, a |

|proposed set of requirements, and recommendations. The full report is available upon request. |

|ACTION |

|The meeting is invited to consider the airport surface communications data requirements relative to AM(R)S|

|allocations needed to support them. |

Abstract

NASA, in cooperation with the FAA, industry, and academia, has been performing research and testing for a new generation of airport surface communications to enable advanced surface CNS systems and improved information distribution and provide lower cost, safer and more efficient airport surface operations. An initial component of this work was an assessment of airport surface communications requirements. NASA commissioned a study to assess current and potential future data communications requirements that could potentially be served by a wireless airport surface network. The study was conducted at a large (Level 12) US airport, namely Dallas-Forth Worth (DFW), in order to obtain an upper limit on data. This paper summarizes the results of the study.

1 - Overview

Air traffic levels have continued to increase, resulting in the Federal Aviation Administration (FAA) and the U.S. Department of Transportation asking the airlines to limit the number of operations at some of the nation’s busiest airports. In the long-term, new runways and airports will be required to address continued growth in air travel, as well as more efficient airport operations, as the airports represent the most significant constraint in increasing air traffic levels overall. In the mid-term, new technologies and procedures are being explored to maximize air traffic throughput at the nation’s airports and airways. The NASA Glenn Research Center is exploring communications concepts and technologies that help to enable the required increases in airport traffic throughput.

The development of an Airport Surface Wireless Network (ASWN) is an important component of this effort. Airport CNS systems are being stressed by this growth and by new applications that require greater telecommunications capacity. In addition, existing infrastructures are aging and are vulnerable to cable cuts and transmission impairments. VHF communications systems used to transport voice have been in use for over 30 years and are limited in their capabilities and unable to meet current and future data communications requirements. A key part of the concepts being explored in the surface movement area is the ability to communicate with sensors and stakeholders that may impact on capacity. To better understand current requirements and project future communication needs, NASA contracted with the Scientific Applications International Corporation (SAIC) (formerly Trios Associates, Inc.) to examine the current and future airport communications requirements with an eye toward developing a high level set of operational requirements for an (ASWN). This paper summarizes the result of the study.

2 – Summary of Results

A summary of the results of each of seven contract tasks is presented below. To adequately address current and future requirements four major stakeholder groups were asked to participate: the Airlines, the FAA, the local airport authority, and airport tenants.

2.1 - Task #1: Airline Operations Communications Systems Requirements

NASA required that an airport with Level 12 traffic be selected to ensure that the bandwidth for this assessment was an adequate representative ASWN. SAIC assessed existing communications systems in use for airline operations at Dallas Fort Worth International Airport (DFW), because it has the third largest number of aircraft operations in the US and it is home to AMR Corporation. AMR Corporation is parent of American Airlines (AA) and American Eagle (AE), the largest airline in the country. AA and AE comprise 73% of all aircraft operations at DFW. In this study, the remaining airlines’ requirements are extrapolated from the AA’s results (backed up by an interview with DFW tenant Continental Airlines). In addition, AA has a major maintenance base at DFW that added significantly to the communications loading, and AA is also one of the most sophisticated users of communications technology in the passenger airline business.

SAIC’s assessment of the AA communications requirements revealed that they have an integrated land-line network, consisting of fiber, copper and wireless elements, that interconnects all AA buildings on airport grounds, including terminals, ramps, baggage handling facilities, hangars, maintenance facilities, and the business center. Flight plans, flight following, Internet, reservations, aircraft maintenance traffic, and baggage identification traffic are examples of the kind traffic that is carried on the American Airlines network

Passenger reservations traffic and ACARS message traffic are the predominant traffic that exists over the AA Networks at the airport. The passenger reservations traffic is destined to the host environment and is used by Systems Operations Control to calculate the weights and balance measurements for the aircraft along with other critical flight parameters. The ACARS message traffic is used to communicate between the air and ground environments information pertaining to the operation of the aircraft. In addition, the messages contained in the ACARS traffic are used to identify changes in flight plans, provide pre departure clearance information to the pilots and communicate aircraft maintenance and performance information to both Systems Operations and Maintenance Operations Centers.

The aggregate bandwidth requirement for American Airlines was estimated to be 45 million bits per second (Mbps). Based on the percentage of AA operations at DFW, the bandwidth requirement for all airlines at DFW was extrapolated to be around 58 Mbps. This data includes data, and voice. Video data is transported via direct fiber connections from the cameras to the video processors without going through the network and is not part of this bandwidth total.

When the difference in total number of airline operations between Chicago O’ Hare and DFW is factored in, the maximum bandwidth requirement for an airport can be estimated to be around 69 Mbps.

Wireless communication for all the airlines mainly involve VHF radios for communications between the airline ramp and the pilot. For other surface activities, trunk radio systems that operating in the 400 or 800 MHz ranges are used. At DFW, approximately 70 frequencies are available for airline to pilot communication and around 180 frequencies are used for airline trunk radio systems.

2.2 - Task #2: FAA Communication Systems

DFW was a good choice for examining FAA surface communications because its configuration is unique with two active Air Traffic Control Towers (ATCT): one for air traffic using the east side of the airport and one for the west side. Each tower has its own communications needs and the need to communicate between towers to coordinate when traffic crosses from the east to west or west to east side runways.

DFW’s FAA communication systems utilize many diverse media types such as copper, fiber, microwave, and wireless technology and span various FAA buildings around the airport. These systems carry ATC voice, surveillance, weather, and other traffic that are critical to DFW airport operations. These communications systems also have redundancy and diversity built in as they were designed with criticality and aviation safety in mind.

DFW is also home to an ASDE-X demonstration system. ASDE-X using ADS-B and Multi-lateration combined with ASDE-3 radar enhances situational awareness for the TRACON, the AA Ramp Control Tower, and the Airport Board.

Analysis of the bandwidth requirement for FAA communications at DFW showed that approximately 23 Mbps is required between the TRACON and the two towers and approximately 12 Mbps is required from the TRACON to other FAA facilities on airport. For a busy airport like Chicago O’Hare, these numbers can be extrapolated to 28 Mbps and 15 Mbps respectively.

Spectrum analysis for FAA systems revealed that around 152 frequencies are being used for ATC voice communication, radio navigation and other services.

2.3 - Task #3: Airport Operations Communication Systems

Because of its size and breadth, DFW provided an opportunity to examine the use of communications by the Airport Board. It should be noted that the U.S. Department of Homeland Security raised the terror alert threat level to Orange during the course of this study. The threat level change made it difficult to capture all DFW Airport Board communications requirements.

Based on the network diagrams and responses to the questionnaires obtained from the Airport Board, the network loading was estimated to be less than 10%. Since the network runs at 100 Mbps in the Access Layer, we estimated that any service on the airport board network cannot have a bandwidth requirement greater that 10 Mbps within the airport. Communications to the outside world was estimated to be close to 7 Mbps based on the infrastructure available. The DFW Airport board actively uses a secure land-mobile radio system that operates in the 800 MHz range with about 32 frequencies as well as a 400 MHz radio system with 6 frequencies.

2.4 - Task #4: Tenant Communications Systems

Trunk radio systems are used by most airport tenants as their primary means of communication. These radio systems operate mainly in the 450 MHz band. Radio systems used by various concessionaires and government agencies also operate 30 MHz, 150 MHz and 170 MHz ranges.

Passenger needs were captured by assuming that passengers would utilize an 802.11g-type wireless network. Bandwidth requirements for passengers are assumed to be equal to the maximum provided by the standard.

In addition to the FAA and AA/AE, DFW is home to significant United Parcel Service (UPS) and Federal Express (FedEx) cargo shipment activities. This provided an opportunity to not only look at additional airlines, but also examine the use of wireless networks by two major airport tenants who use wireless networks as part of their day-to-day business.

UPS’s LAN in their package sorting facility was assessed to gather the land-line and wireless communications requirements. Their wired LAN consists of a single LAN with Cisco switches/routers interconnected by fiber and copper. The network does not have outside access to any other entities at the airport. Instead, a phone system is used for this function. A fractional T-1 is used for off airport access to corporate headquarters. An 802.11b wireless LAN system is used for scanning packages from loading gates.

2.5 - Task #5: Existing Systems Assessment

Specific interface characteristics, protocols, and data rates of the communications systems used by airlines were collected. Databases with FAA and airport tenant information are provided with the final report. A summary of the analysis of the data for all stakeholders is included in section 5 of the final report.

2.6 - Task #6: Services Description and Criticality Evaluation

From the document search and on-site interviews the team was able to determine the criticality of the applications that might traverse the ASWN. The FAA, airline, airport board critical applications have been identified in task 6. For airline operations, any service interruptions that affects schedules are critical. For FAA, all communications, navigation, and surveillance systems are critical. Hazardous weather systems are also considered critical. For the airport board, police, fire, and emergency as well as other airport operations in the surface movement area are considered critical.

2.7 - Task #7: Current Wireless Systems

To get a better understanding of the frequencies in and around DFW, SAIC obtained the output of the National Telecommunications and Information Administration (NTIA) frequency database for an 8 mile radius with origin being at the center of the DFW area. The Aeronautical Frequency Committee (AFC), operated by ARINC for the industry,

provided the Federal Communications Commission (FCC) equivalent that included the ARINC used frequencies at DFW. SAIC combined both of these outputs into a single database. The database contains approximately 20,000 frequency assignment records, with a minimum of overlap (~approx. 500 records). When scaled down to address only the frequencies used inside the fence line of the airport, there are approximately 4800 assignments.

One of the largest users and re-users of frequencies is NEXTEL with approximately 2500 assignments, of which 700 are unique, in the 800 MHz range. DFW also crosses multiple jurisdictions (e.g., Grapevine, Irving, Ft. Worth). Communications occurring inside the airport fence line, whether they are municipal or commercial are also included in our study and database. With the spectrum use database, the number of frequencies, the range of channels used, and the power levels a good overview of spectrum use and the identity of the users was obtained. The users range from MacDonald’s to the FAA to NEXTEL to ARINC.

802.11b type wireless LAN systems are currently deployed at DFW airport terminal area for passenger Internet and VPN access.

Questionnaires, literature searches, documentation searches, and on-site interviews were also performed. Documentation searches were conducted on the following sources: the FAA, the Airline Electronic Engineering Committee (AEEC), RTCA, International Civil Aviation Organization (ICAO), and NASA. Most of this data is available on-line. The websites are listed in the reference section. On-site interviews were conducted and proved to be valuable in understanding the operating environment for the ASWN, criticality of the applications traversing the ASWN, and discovering various network diagrams for all of the participating stakeholders. In addition, SAIC was able to use data generated from some of its FAA contracts to obtain needed expertise or information.

With the information gathered, Excel Spreadsheets were generated that enabled the determination of the communications traffic loading requirements for the ASWN based on the current copper, fiber, and microwave systems.

So that operational requirements other than traffic load could be identified, a set of assumptions was created that helped to bound the answer. Should any of the assumptions be changed then the requirements will need to be reviewed and possibly revised. Should the requirements change as they are being validated and decomposed then the assumptions should be checked for validity.

3 - Proposed Set of Requirements:

The main result of this study is a set of proposed requirements including technical, performance, security, system safety and policy aspects, whether the ASWN is used for wireless, wire-line replacement, aircraft to controller voice, or data link systems. Below is a subset of the performance requirements:

1. The ASWN, for aircraft to ground, communication shall meet the required communication technical performance of 770 ms 95% of the time and the continuity, availability and integrity numbers as specified in, Appendix C1, section 5, RTCA DO-284 and DO-284 change 1, Table 5-2.1.

2. The ASWN shall have the following minimum data rates for each segment of the user community:

a. FAA: ~28 Mbps (TRACON to Tower), ~15 Mbps (TRACON or ATCT to RTRs, NAVAIDS, ASR-9 Radar, DBRITE, Weather Sensors, etc.). Does not include ASDE-3.

b. Airlines: ~ 69Mbps

c. Airport: 7 Mbps for data

d. Passengers: 54 Mbps

3. The ASWN shall be expandable, at a minimum, to 200% of its minimum data and voice capacity requirements to support growth.

4. The ASWN shall be capable of supporting end-to-end services that have 0.99999 availability with a six second mean-time-to-restore in accordance with FAA Order 6000.36 and the NAS-SR-1000.

5. The ASWN latency, when used as a wire-line replacement to an ATC voice and data communication site, shall not exceed 25 ms in one direction.

4 - Concerns/Limitations/Recommendations

Based on the data gathered and analysis performed, the authors of this study offer the following concerns, limitations, and recommendations:

• Based on FAA requirements, do not combine the radar, ADS-B, and NAV/Landing systems in with the communications functions. No load for NAV/Landing signals to the aircraft is assumed in this analysis. Any load estimate would be based on conjecture and a proposed system design that does not exist.

• ASDE-3 radar data rate (~400 Mbps) is well beyond the capabilities of current digital RF technology. Therefore it was not included in the bandwidth calculations listed in the requirements section of this report.

• To meet the 200% growth in communications needs, new technology may be required.

• Communications requirements for the ASWN will need re-assessment as concepts and resulting systems evolve.

5 – Summary

The SAIC study covered all airport communications requirements that could potentially be served by a future airport surface wireless network. These requirements represent the maximum for the largest airports in the United States. The total for all services is approximately 173 Mbps. A wireless network configured to service only ATC, AOC and other safety-related services would require a subset of this total, depending on how services are allocated between critical and non-critical safety services, would probably require approximately 40 to 50% of this total.

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