Communication
1. ATS Service Network, ASN
The existing communication circuits (both voice and data) of current CAA ATS facilities use point-to-point dedicated leased lines. To increase the circuit availability and to provide redundancy, two leased lines are often run in parallel. Because of the large number of circuits, the workload on the maintenance personnel to ensure circuit availability is correspondingly high. The cost associated with circuit lease and maintenance represents a significant part of ANWS’s operational budget. With the advent of digital networking, there is a huge incentive to replace most of the leased circuits with a network dedicated to the CAA’s ATS-related traffic.
Asynchronous Transfer Mode (ATM) network technology is a mature technology, and it improves service availability by providing circuit rerouting to circumvent circuit failures. To meet the Taipei FIR’s intra-FIR communications requirements, the CAA has selected ATM network technology for the ATS Service Network (ASN). Furthermore, the increased reliability and maintainability of the ASN will significantly reduce the maintenance workload.
To cope with unexpected interruptions on ground circuits, which would normally cause the stoppage of the ground-ground communications network service, satellite communications could be included as part of the ASN to provide backup connections from radar sites to the North and South ATS Parks, and to connect voice channels between ATS facilities. Satellite communications network service will be implemented as the ASN Phase IV, the implementation of which will begin in 2009.
ASN will provide data transmission between all systems in the CNS/ATM program, including between the next generation ATMS and its peripheral support system. Network security will play a very important role and will be enhanced with VPN and firewall technologies. This program will be implemented in the four phases described below:
a.Phase I:
Beginning in 2003, adopted non-synchronized network transmission mode to implement the ATM backbone network to connect ATS facilities (Shan Tiao Chiao Radar, Chiayi Navigation Aid Station, Hengchun Navigation Aid Station, etc.), towers, communication maintenance units (Xiang An), aerodromes (Taoyuan Airport, Kaohsiung Airport, Taitung Airport, etc.) and airlines, etc. Figure 1 shows the network configuration.
Figure 1. ASN Network configuration
b.Phase II:
From 2005 to 2006, complete Northern digital microwave ring data protection routing system. The system will connect Taoyuan Aviation Facilities Sector, Da-dong Mountain, Linkou, Songshan Aerodrome, Da-tun Mountain and Xiang-An Building to form a two-way ring data protection routing system. This system will ensure that ATC data will continue to be transmitted if there is a failure in any section of the network.
c.Phase III:
From 2007 to 2008, extend the ASN network to the new North and South ATS Parks. The expansion of ASN in this phase will also include upgrade of the ASN with NGSDH functionality to meet the new ATMS networking needs.
d.Phase IV:
Begin to implement satellite links for redundancy in 2009.
2. ATS Message Handling System, AMHS
According to the planning concept of ICAO, the AMHS was to be broadly used in the Asia-Pacific Region by 2005. The CAA has planned the AMHS implementation in accordance with the ICAO CNS/ATM plan and augmented with the specific requirements of the Taipei FIR. The AMHS implementation is part of the Communications Sub-plan of the CNS/ATM Plan. Currently, Hong Kong and Fukuoka FIRs (2 ATN Backbone Sites) are connected to Taipei FIR through the AMHS Bridge and Gateway. Other ATN Backbone Sites (Australia, China, India, Singapore, Thailand, and US) and ATN Site would be connected to Taipei FIR through these 2 ATN Backbone Sites. The AMHS system will connect directly to the adjacent FIRs’ AMHS systems when the implementation is accomplished. The Asia/Pacific ATN network configuration is shown as Figure 2.
Figure 2. The Asia/Pacific ATN network configuration
The AMHS system will be implemented on ATN and replace the current AIMS system. The AMHS system will exchange information with other FIRs in the future. In the Asia-Pacific Region, most countries have not implemented the AMHS system. The CAA will connect with these countries through the AMHS Bridge as part of the AMHS system, to provide uninterrupted services.
After the completion of the North and South ATS Parks and ASN network expansion in 2007, the AMHS system will be relocated to the new North ATS Park in 2009. The website configuration of CNS/ATM AMHS system terminal user is divided into internal user and external user. The external user access through internet and the airlines log in the system through the VPN. Non-CAA users will be restrained by adopting the firewall and the internal users can connect with other units through the internal internet. The Figure 3 depicts the AMHS terminal user network configuration in the CNS/ATM plan.
Figure 3. AMHS terminal user network configuration
3. AMHS Spare Parts Procurement
To effectively maintain the AMHS, the CAA together with Thales IS identified the inventory of spare parts that will be required to maintain the procured AMHS.The contract for the spare parts procurement was signed on 14 July 2004, and the spare parts procurement was completed in October 2005.
4. Implementation of D-VOLMET and D-ATIS
According to the regulations of ICAO Annex 3, the meteorological authority should report meteorological information including METAR, SPECI, TAF, SIGMET, AIRMET, and Special Air-reports not contained in SIGMET etc., to aircraft in flight. This service is called “VOLMET”. VOLMET service uses Very High Frequency (VHF) or High Frequency (HF) transmitters to broadcast voice meteorological information, or data link transceivers to provide data meteorological information, to aircraft in flight, including specific aerodromes’ meteorological information.
Because the CAA is not a member of ICAO, ICAO assigned Taipei FIR’s VOLMET broadcast service to Hong Kong. To achieve conformity with ICAO international standards, the CAA resolved to implement Voice/Data link VOLMET. In addition to planning the Voice/Data link VOLMET system, the CAA decided to upgrade the current ATIS systems in Taoyuan, Kaohsiung, and Songshan aerodromes. After the commissioning of AMHS, the upgraded system is able to extract the meteorological text from AMHS and incorporate some additional system functions as suggested by controllers, the CAA plans to implement Voice/Data link VOLMET and ATIS via system integration to provide complete meteorological information service and promote operational efficiency in Taipei FIR at aerodromes, in terminal airspace and in en-route airspace. The final system acceptance of this program has been completed in December 2005 and the system is now operational. The data will be uploaded to the VOLMET server of the Information Management Center by the VOLMET working station of Taipei Aeronautical Meteorological Center. Afterwards, the Information Management Center will transmit the data to the ATIS server of other units by the digital audio ATIS. The aircraft is able to receive the data by the radio or satellite. The structure of D-VOLMET and D-ATIS is shown in Figure 4.
Figure 4. Structure of D-VOLMET and D-ATIS
5. Data Link Service Provider Selection
The DSPs offer global service. Through their air-ground (radio and geostationary satellites) and ground-ground communication service networks, aircraft operators can connect to the air traffic service information stations and to terminals through the DSPs’ air-ground and ground-ground communication service networks. DSPs offer a sound network management control system, and can service flights using different ACARS specifications (AEEC, 620, 623).
At present most international aircraft have ACARS capability, and use it to communicate via air-ground data-link with the data communication ground stations. Because data-link service provides worldwide coverage, system facilities and network maintenance require large investment. Most countries do not set up their own global data-link service network; instead, they lease data link services from SITA and ARINC.
DSPs have offered data link communication services to airlines and air traffic service providers, giving their ATC units the ability to provide more efficient CPDLC, PDC, and AIDC through data link; this includes the ability to provide dynamic surveillance data to the cockpit. The CAA’s initial implementation of these services via a DSP is in line with ICAO FANS and relevant industry standards. Data link communications system configuration is shown as Figure 5.
Figure 5. Data link communications system configuration
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