Vhf Datalink

VHF DataLink I. VHF datalink

VDL ( VHF data link ) c¸c giao thøc cÇn thiÕt cho viÖc trao ®æi d÷ liÖu híng liªn kÕt trong ®êng liªn kÕt d÷ liÖu VHF A/G. C¸c kiÓu VHF Data link kh¸c nh©u ®îc ®Þnh nghÜa gåm : - Mode 1 : §a truy nhËp ph¸t hiÖn sãng mang víi ®iÒu chÕ MSK _ AM t¹i tèc ®é 2.4 Kb/s - Mode 2 : §a truy nhËp ph¸t hiÖn sãng mang víi ®iÒu chÕ D8PSK t¹i tèc ®é 31.5Kb/s - Mode 1 : §a truy nhËp ph©n chia thêi gian víi ®iÒu chÕ D8PSK t¹i tèc ®é 31.5 Kb/s tÝch hîp dÞch vô tho¹i vµ d÷ liÖu - Mode 4 : C«ng nghÖ nµy ®ang ®îc xem lµ c«ng nghÖ cho hiÖn t¹i dïng c«ng nghÖ STDMA (§a truy nhËp tù ®éng ph©n chia khe thêi gian ) ®iÒu chÕ GFSK vµ D8PSK. VDL (VHF data link) defines the protocols needed to exchange bit-oriented data across an air/ground VHF data link in an ATN compliant environment. Different forms of VHF data link have been defined: Mode 1 - CSMA with MSK-AM modulation at 2.4 kbit/s (similar to ACARS); Mode 2 - CSMA with D8PSK modulation at 31.5 kbit/s; Mode 3 - TDMA with D8PSK modulation at 31.5 kbit/s providing integrated voice and data services; Mode 4 - current candidate technology for Mode 4 is STDMA providing data only services with GFSK or D8PSK modulation.

1 VDL Mode 1 VDL mode 1 lµ hÖ thèng truyÒn d÷ liÖu híng liªn kÕt tèc ®é thÊp. HÖ thèng nµy sö dông chÕ ®é ®a truy cËp ph¸t hiÖn sãng mang phï hîp víi hÖ thèng ACARS hiÖn t¹i ( t¹i cïng tèc ®é d÷ liÖu) vµ líp thø 2 vµ thø 3 cña m« h×nh OSI. ICAO SARPs ®· hoµn thµnh VDL Mode 1 nµy. VDL Mode 1 is a low-speed bit-oriented data transfer system. It used a CSMA (Carrier Sense Multiple Access) channel access mode. The physical layer conforms with the existing ACARS system (at the same data rate) and layer 2 and 3 to OSI protocols. ICAO SARPs completed.

2 VDL Mode 2 VDL Mode 2 t¬ng tù nh VDL mode 1. nhng CDL Mode2 sö dông kiÓu ®iÒu chÕ hiÖu qu¶ h¬n ®Ó n©ng cao tèc ®é d÷ liÖu. Mét trong nh÷ng h¹n chÕ lín nhÊt cña Mode 2 lµ kh«ng cung cÊp d÷ liÖu cho prioritization. The ICAO SARPs ®· ®îc hoµn thµnh vµ th«ng qua. VDL Mode 2 is similar to the VDL Mode 1 in many ways. Yet VDL Mode 2 uses a much

more efficient modulation scheme to support a greatly improved data rate. One of the most significant limitations of Mode 2 is the lack of support for prioritisation of data. The ICAO SARPs have been completed and validated.

3 VDL Mode 3 VDL Mode 3 is an integrated voice and data link technology based on the TDMA (Time Division Multiple Access) principle. Mode 3 will support a priority scheme. The Mode 3 SARPs are expected to be adopted in Spring 1999. Validation of the vocoder is expected to be completed by late 1998. VDL modo 3 lµ tÝch hîp gi÷a tho¹i vµ ®êng d÷ liÖu c¬ së c«ng nghÖ dùa trªn nguyªn lý TDMA(®a truy nhËp theo thêi gian).Mode 3 sÏ cung cÊp lîc ®å u tiªn. The Mode 3 SARPs ®îc mong chê ®Ó dïng thö trong mïa xu©n n¨m 1999.TÝnh hiÖu lùc cña nã ®îc mong ®îi hoµn thµnh sau n¨m 1998.

4 VDL Mode 4 Self-Organizing Time Division Multiple Access (STDMA). STDMA is a concept that is being promoted as VDL Mode 4 . It uses a number of 25 kilohertz (KHz) channels in the very high frequency (VHF) band. Transmissions are co-ordinated in the sense that only one aircraft transmits in any slot in any channel and each aircraft is equipped with a receiver as well as a transmitter. STDMA data is transmitted at a rate of 31.5 or 19.2 kilobits per second (kbps). Each aircraft’s transmission would be accompanied by an off period (guard time) of several milliseconds to account for differences in transmission times between transmitters and receivers. The STDMA design has yet to be validated and is considered to be unstable at this point in time. Draft SARPs are currently under development. §a truy cËp ph©n chia theo thêi gian tù thiÕt lËp (STDMA). STDMA lµ mét kh¸i niÖm ®ang ®îc t¨ng cÊp nh VDL mode 4. Nã sö dông mét phÇn cña c¸c kªnh 25 KHz trong b¨ng tÇn VHF. Sù truyÒn th«ng lµ b×nh thêng khi ph¸t hiÖn chØ mét tµu bay ph¸t tÝn hiÖu trong mét khe cña mét kªnh vµ mçi tµu bay ®îc trang bÞ mét m¸y thu t¬ng thÝch víi m¸y ph¸t. D÷ liÖu STDMA ®îc truyÒn víi tèc ®é 31.5 hoÆc 19.2 Kb/s. Qu¸ tr×nh truyÒn cña mçi tµu bay cã thÓ kÌm theo mét kÕt thóc chu kú (thêi gian b¶o vÖ) kho¶ng vµi mili gi©y ®Ó ph©n biÖt thêi nh÷ng kho¶ng thêi gian truyÒn gi÷a m¸y ph¸t vµ m¸y thu. X©y dùng STDMA ®· tÝnh ®Õn kho¶ng thêi gian b¶o vÖ nµy. hiÖn nay Draft SARPs kh«ng ph¸t triÓn STDMA.

II. Mode S Data Link §êng d÷ liÖu mode S

The Mode S is an evolution of the traditional Secondary Surveillance Radar (SSR), which is based upon Mode A/C interrogation/reply scheme. In the Mode S system, this scheme has been enhanced, by uniquely identifying each aircraft using a world wide 24 bit aircraft address, and by allowing the transmission of interrogations selectively addressed to a single aircraft, instead of being broadcast in the whole antenna beam. Mode S lµ mét ph¸t triÓn cho truyÒn th«ng rada gi¸m s¸t thø cÊp (Secondary Surveillance Radar SSR), Mode S dùa trªn c¬ së lîc ®å hái ®¸p mode A/C. Trong hÖ thèng mode S, s¬ ®å hái ®¸p ®îc x©y dùng bëi sù nhËn d¹ng duy nhÊt mçi tÇu bay sö dông trªn thÕ giíi víi ®Þa chØ nhËn d¹ng tµu bay 24 bÝt, vµ cho phÐp lùa chän tÝn hiÖu dß hái ®Þa chØ truyÒn ®i ®Õn mét tµu bay thay v× c¸ch ph¸t qu¶ng b¸ cho toµn bé tµu bay. A Mode S radar is able to perform surveillance (i.e. to output the aircraft position, in addition to the standard SSR modes (Mode 3/A, Mode C)). It also has data-link capabilities, i.e. the ability to send or extract frames containing binary data. The data-link can operate only on aircraft being tracked by the surveillance processing. From an operational point of view, the priority is always given to the surveillance processing (the detection of a target and the transmitting of the corresponding information shall never be degraded for any data-link reasons). Mét rada sö dông mode S cã thÓ thùc hiÖn gi¸m s¸t (vÝ dô nh c¨n cø vµo tÝn hiÖu ph¸t ra tõ vÞ trÝ tµu bay, trong phÇn tÝn hiÖu bæ xung tíi c¸c chÕ ®é rada gi¸m s¸t thø cÊp tiªu chuÈn (Mode 3/A, Mode C)). Nã còng cã kh¶ n¨ng liªn kÕt d÷ liÖu b»ng c¸ch göi hoÆc trÝch tõ c¸c khung chøa d÷ liÖu d¹ng nhÞ ph©n. §êng liªn kÕt d÷ liÖu cã thÓ ho¹t ®éng xö lý gi¸m s¸t chØ víi tµu bay ®ang bay. Tõ mét ®iÓm ho¹t ®éng trong hµnh tr×nh, quyÒn u tiªn lu«n ®îc giöi ®Õn hÖ thèng xö lý gi¸m s¸t (môc tiªu ®îc ph¸t hiÖn vµ truyÒn th«ng tin gãc ®ång vÞ th«ng tin nµy sÏ kh«ng bao giê bÞ suy gi¶m trªn ®êng liªn kÕt d÷ liÖu víi bÊt kú lý do nµo). The selective addressing ability of Mode S lends itself to be the basis of a data link. ICAO has developed (and overseen the validations of) SARPs for the Mode S subnetwork. The Mode S subnetwork comprises a ground component (GDLP) and an airborne component (ADLP) that provide an ATN compliant interface to the airborne and ground routers respectively . Kh¶ n¨ng lùa chän ®Þa chØ cña chÝnh mode S trë thµnh c¬ së cña ®êng liªn kÕt d÷ liÖu. ICAO ®· ph¸t triÓn (vµ gi¸m s¸t tÝnh hiÖu lùc cña )SARPs cho Mode S subnetwork . Mode S subnetwork bao gåm thµnh phÇn mÆt ®Êt

(GDLP) vµ thµnh phÇn trªn kh«ng (ADLP) chóng cung cÊp cho mét ATN theo giao diÖn víi phÇn trªn kh«ng vµ ®Þnh tuyÕn mÆt ®Êt riªng biÖt.

III. Analysis Options for Initial Air/Ground Data

Networks (EATCHIP COM.ET2.ST15) ph©n tÝch lùa chän cho m¹ng d÷ liÖu Air/Ground ban ®Çu 3.1 General- Tæng quan:

The objectives of the EATCHIP COM.ET2.ST15 were to : “to identify the most mature application(s) (from an operational point of view), amongst ATC applications; to propose two or three schemes of both data link applications and air/ground communication technologies which can be implemented in the various homogeneous ECAC areas within the next five to ten years; to propose an implementation plan for each scheme with special care to its integration into the ATN environment.” Môc ®Ých cña EATCHIP COM.ET2.ST15 lµ: • “NhËn diÖn phÇn lín c¸c øng dông ®· sö dông (c¨n cø vµo mét ®iÓm trong hµnh tr×nh), øng dông trong ATC;

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§a ra hai hoÆc ba kÕ ho¹ch thùc hiÖn cña c¶ hai øng dông ®êng liªn kÕt d÷ liÖu vµ kü thuËt truyÒn th«ng air/ground nã cã thÓ trë thµnh ph¬ng tiÖn trong vïng ECAC kh«ng ®ång nhÊt trong vßng 5 ®Õn 10 n¨m tíi;

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§a ra mét kÕ ho¹ch kh¶ thi cho mçi kÕ ho¹ch víi sù thËn träng ®Æc biÖt ®Ó thèng nhÊt trong m«i trêng ATN “

To reach these objectives the study was accordingly divided in three main steps : Nghiªn cøu c¸c môc ®Ých trªn ®îc chia lµm ba bíc chÝnh: Phase 1: Inventory and Analysis of air/ground ATS applications, of experiments and trials, of the planned or existing air/ground data networks and of the plans and policies of the different actors (CAAs, Airlines, Industry, and Network Service Providers). Phase 2: Criteria selection and choices for the most appropriate combination of ATS applications and air/ground data networks. From this set of choices two or three options will be selected. The list of criteria will be established in considering both the ground

side for the different homogeneous areas and the airborne side. Phase 3: Feasibility study, a subsequent deployment strategy plan (one per option) will be provided. All three Phases have been completed.

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Giai ®o¹n 1: ®¸nh gi¸ vµ ph©n tÝch c¸c øng dông cña air/ground ATS, cña thö nghiÖm vµ th¨m dß, cña kÕ ho¹ch vµ m¹ng d÷ liÖu air/ground hiÖn cã, vµ cña kÕ ho¹ch vµ chÝnh s¸ch kh¸c nhau (CAAs, c«ng ty hµng kh«ng, nhµ cung cÊp dÞch vô m¹ng).

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Giai ®o¹n 2: lùa chän tiªu chuÈn vµ lùa chän phÇn lín c¸c kÕt hîp thÝch hîp cña c¸c øng dông ATS vµ m¹ng d÷ liÖu air/ground. Tõ 2 hoÆc ba c¸c bé chän trªn sÏ ®îc chän. Danh s¸ch cña c¸c tiªu chuÈn sÏ ®îc chÝnh thøc ho¸ trong c¶ hai phÇn mÆt ®Êt cho vïng kh«ng ®ång nhÊt vµ phÇn phÇn trªn kh«ng. Giai ®o¹n 3:nghiªn cøu tÝnh kh¶ thi, mét kÕ ho¹ch chiÕn lîc ph¸t triÓn sau (mét trªn sè lùa chän) sÏ ®îc cung cÊp

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3.2 Phase 1 Report - Inventory and Analysis of A/G Applications and Data Networks B¶n b¸o c¸o giai ®o¹n 1 – b¶n tãm t¾t vµ ph©n tÝch c¸c øng dông cña A/G vµ c¸c m¹ng d÷ liÖu The Phase 1 study [EAT13] concluded with a number of possible combinations of data link technology and services as summarised in the table below which is reproduced from the Phase 1 report. The SARPs for TP4/ATN/VDL/CSMA1 (Mode 2) have since been completed and validated. “The table lists, in an ATN perspective, the 11 main datalink services (consisting of a protocol stack, equipment type and/or access method over a given air-ground medium) and the main technical; operational and political factors favouring or hampering their availability in the 1995-2005 time range. Nghiªn cøu giai ®o¹n mét [EAT13] kÕt thóc víi mét sè kh¶ n¨ng kÕt hîp cña kü thuËt ®êng liªn kÕt d÷ liÖu vµ c¸c dÞch vô nh tæng kÕt trong b¶ng cho díi ®©y nã ®îc sao chÐp l¹i tõ b¶n b¸o c¸o giai ®o¹n 1. The SARPs for TP4/ATN/VDL/CSMA1 (Mode 2) ®· ®îc hoµn thµnh vµ th«ng qua. “b¶ng danh s¸ch, trong mét m«i trêng ATN, 11 dÞch vô cña ®êng liªn kÕt chÝnh (gåm cã mét giao thøc, kiÓu thiÕt bÞ vµ hoÆc ph¬ng ph¸p truy cËp

vµo mét air-ground trung b×nh ) vµ kü thuËt chÝnh; chÝnh s¸ch u ®·i ho¹t ®éng cho ngêi qu¶n lý hoÆc c¶n trë tÝnh hiÖu lùc trong kho¶ng thêi gian 1995-2005 ”

3.3 Phase 2 Report - Criteria Selection and Options B¶n th«ng b¸o giai ®o¹n 2 – tiªu chuÈn lùa chän vµ sù lùa chän Having defined various criteria for the selection of data link technology/service combinations (e.g. only addressing those data link services and air-ground technology that will be available in the 2000 and 2005 time-frames) the Phase 2 study concluded the following: §Þnh nghÜa tiªu chuÈn kh¸c nhau cho sù lùa chän c«ng nghÖ/dÞch vô kÕt hîp cña ®êng d÷ liÖu (vÝ dô nh: chØ m×nh dÞch vô ®Þa chØ c¸c ®êng d÷ liÖu ®ã vµ c«ng nghÖ air-ground ®ã sÏ cã hiÖu lùc trong kho¶ng thêi gian 20002005) giai ®o¹n 2 nghiªn cøu gi¶i quyÕt nh sau: Recommendations for 1997 – 2000 KhuyÕn nghÞ 1997-2000 1997 - 2000: Due to the very short time horizon, only existing technology can be considered. Therefore, an ACARS based Datalink is considered for providing non mandatory and non time and safety critical Services. The concerned services are Automated Terminal Information Service (ATIS), Oceanic Clearance Message (OCM) and Departure Clearance (DCL). 1997-2000: cã hiÖu lùc trong ph¹m vi thêi gian rÊt ng¾n, chØ c«ng nghÖ hiÖn cã míi cã thÓ ®¸p øng ®îc. Tuy nhiªn, mét ACARS ®êng d÷ liÖu c¬ së ®· ®îc xÐt kü ®Ó chuÈn bÞ ®Çy ®ñ kh«ng cã tÝnh b¾t buéc vµ kh«ng thêi gian vµ an toµn khi dÞch vô nguy cÊp. DÞch vô cã liªn quan lµ dÞch vô cung cÊp th«ng tin ®Çu cuèi tù ®éng (ATIS), th«ng b¸o rêi bÕn ngoµi biÓn (OCM), vµ dÉn ®êng rêi bÕn (DCL). Option 1: OCM, DCL and ATIS over ACARS/VHF Tuú chän 1: OCM, DCL vµ ATIS qua ACARS/VHF Option 2: NAT-ADS over ATN/SatCom Data 3 Tuú chän 2: NAT-ADS qua ATN/SatCom Data 3 Option 1 represents early continental applications that can be deployed on the ACARS system (then migrated in one step to the VDL/Mode 2). Tuú chän 1 tr×nh bµy ban ®Çu øng dông ë lôc ®Þa nã cã thÓ triÓn khai trªn hÖ thèng ACARS (sau ®ã lan dÇn tong bíc mét ®Õn VDL/Mode 2) Option 2 represents early NAT area applications, which are mentioned here for the sake of completeness. Tuú chän 2 tr×nh bµy ban ®Çu øng dông ë vïng NAT, ®iÒu ®ã ®îc ®Ò cËp ë ®©y v× lêi Ých céng ®ång. Recommendations for 2000 – 2005

KhuyÕn nghÞ 2000 - 2005 “2000 to- 2005: For this time period it was proposed to study the VDL (Mode 2) system as a candidate for a main subnetwork. It was also proposed to study the VDL Mode 4, the Mode S and the SATCOM systems as possible complementary options. The COM Team amended the proposal of the Phase 2 study by requesting that the VDL Mode 4 subnetwork be examined as a candidate for a main subnetwork in addition to VDL Mode 2 subnetwork”. [EAT 19] “2000-2005 thêi gian nµy lµ thêi kú trong kÕ ho¹ch nghiªn cøu hÖ thèng VDL (Mode 2) nh mét øng cö cho mét m¹ng con chÝnh. Nã còng ®îc ®Ò nghÞ ®Ó nghiªn cøu VDL Mode 4, the Mode S vµ hÖ thèng SATCOM cã thÓ nh lµ bæ sung cho sù lùa chän. The COM Team söa ®æi ®Ò xuÊt trong giai ®o¹n 2 nghiªn cøu bëi yªu cÇu cho the VDL Mode 4 m¹ng con ®îc xem nh mét øng cö cho m¹ng con chÝnh bæ sung cho m¹ng con VDL Mode 2 ” [EAT 19] The study concluded that: Nghiªn cøu kÕt luËn : “Continental area : Taking into account the results of the datalink ranking (chapter 3.4) and the results of the QoS matching analysis (conducted in chapter 4), the VDL-CSMA/Mode 2 can be proposed as the main option. This is due to its position in the datalink ranking and the fact that most of the applications requirements are met by the VDL-CSMA/Mode 2. For providing a secondary/backup option, we have to choose among the remaining datalinks which satisfy most of the applications requirements. Using the compliance matrix introduced in chapter 4, there are two possible options: the Mode S ATN full network scenario and the STDMA ATN integration scenario. The comfort margins matrices for throughput and transfer delay show that both Mode S ATN and STDMA ATN provide the same margins. However, for STDMA the margins decrease noticeably when the number of aircraft increases, whereas for Mode S this is not the case. On the other hand, STDMA presents more advantages in terms of adaptability to other applications and especially to Navigation. As a consequence, we propose jointly Mode S and STDMA for building up a second option

for the whole ECAC area, owing to their mutually complementary coverage. Note again that we recommend them only as a backup to VDL CSMA/Mode 2. Satcom data 3, which has been already retained as the main option for the NAT area by year 2000, could also be envisaged as a backup to VDL for the ECAC area in the timeframe 2000-2005. vïng lôc ®Þa: kÕt qu¶ tÝnh to¸n cña hµng datalink (ch¬ng 3.4) vµ kÕt qu¶ cña OoS khíp víi ph©n tÝch (dÉn ra trong ch¬ng 4), the VDL-CSMA/Mode 2 cã thÓ ®îc ®Ò xuÊt nh lµ sù lùa chän chÝnh.§©y lµ quyÒn cña vÞ trÝ trong hµng datalink vµ sù thËt lµ phÇn lín øng dông ®ßi hái ®îc cung cÊp bëi the VDL-CSMA/Mode 2. Cho dù phßng thø hai / sù lùa chän sao chÐp dù phßng, chóng cã thÓ ph¶i chän gi÷a phÇn cßn l¹i cña c¸c datalink ®iÒu ®ã lµm tho¶ m·n phÇn lín øng dông ®ßi hái.Trong ch¬ng 4 giíi thiÖu c¸c sö dông chÊp nhËn ®îc, cã hai nsù lùa chän cã thÓ thùc hiÖn ®îc lµ: the Mode S ATN m¹ng ®Çy ®ñ t¬ng lai vµ the STDMA ATN sù më réng t¬ng lai. C¸c ma tr©n dù tr÷ thuËn tiÖn cho th«ng lîng vµ trÔ chuyÓn giao chØ ra r»ng c¶ hai Mode S ATN and STDMA ATN chuÈn bÞ sè dù tr÷ .Tuy nhiªn, ®¸ng lu ý lµ STDMA gi¶m bít sè dù tr÷ khi sè tµu bay t¨ng, nhng ngîc l¹i Mode S nµy kh«ng cã trêng hîp nµy. MÆt kh¸c, STDMA hiÖn t¹i thuËn lîi h¬n trong giíi h¹n cña kh¶ n¨ng thÝch øng ®Õn c¸c øng dông kh¸c vµ ®Æc biÖt ®Õn sù ®iÒu híng. Nh mét kÕt qu¶, chóng ®Ò xuÊt Mode S and STDMA cïng nhau x©y dùng nªn sù lùa chän thø hai cho toµn bä vïng ECAC , nhê cã sù bæ sung qua l¹i tin tøc ®a ra. Chó ý lÇn n÷a r»ng chóng ta giíi thiÖu nã nh lµ mét sao chÐp dù phßng cho VDL CSMA/Mode 2. Satcom data 3,®· ng¨n l¹i nh sù lùa chän chÝnh cho vïng the NAT n¨m 2000,cã thÓ dù tÝnh nh mét sao chÐp dù phßng tíi VDL cho vïng the ECAC trong kho¶ng thêi gian 2000-2005. NAT area: For the non-continental side, the QoS matching results (chapter 4), it seems logical to propose Satcom data 3 as the first option for the best datalink to support non-continental applications. As shown in chapter 3.4, the HF datalink is seen as a good candidate in terms of cost. But since the proposed throughput is too low (see the throughput margins matrix), HF is proposed only as a secondary/backup option in the NAT area.” Vïng NAT: Cho n¬i kh«ng ph¶i lµ lôc ®Þa, the QoS kÕt qu¶ phï hîp (ch¬ng 4), nã cã vÎ nh logic ®Ó ®Ò xuÊt Satcom data 3 nh sù lùa chän thø nhÊt cho datalink tèt nhÊt ®Ó cung cÊp øng dông ë n¬i kh«ng ph¶i lµ lôc ®Þa. Nh chØ ra trong ch¬ng 3.4, the HF datalink nh lµ øng cö tèt trong giíi h¹n chi phÝ. Nhng tõ th«ng lîng ®îc ®Ò nghÞ trong kÕ ho¹ch lµ qu¸ thÊp (nh th«ng l-

îng ma trËn dù tr÷), HF ®îc ®Ò xuÊt chØ nh thø hai / b¶n sao chÐp dù tr÷ sù lùa chän trong vïng NAT”

3.4 Status of Phase 3 - Feasibility Study Nghiªn cøu tÝnh kh¶ thi tr¹ng th¸i cña giai ®o¹n 3 The objective of this phase is to study the feasibility of the options selected in Phase 2 in terms of the technical feasibility, cost and implementation programme. Taking into account the Phase 2 proposal and the decision of the COM Team, the Phase 3 was split into two parts: one dealing with the short term horizon (1997 2000) and another dealing with the medium term horizon (2000 - 2005). The Phase 3.1 report, deals with an implementation plan for ACARS [EAT8] and the Phase 3.2 report deals with the implementation feasibility of the Air/Ground data subnetworks identified by Phase 2 of the ST15 study Môc ®Ých cña giai ®o¹n nµy lµ nghiªn cøu tÝnh kh¶ thi cña giíi h¹n tÝnh kh¶ thi kü thuËt trong sù lùa chän ë giai ®o¹n 2, cã gi¸ trÞ nh mét ch¬ng tr×nh bæ sung. TÝnh to¸n ®Ò xuÊt trong giai ®o¹n 2 vµ sù gi¶i quyÕt cña nhãm COM, giai ®o¹n 3 ®· chia ra lµm 2 phÇn: mét phÇn cã ph¹m vi giíi h¹n ng¾n (19972000) vµ mét cã ph¹m vi giíi h¹n trung b×nh (2000-2005). B¸o c¸o giai ®o¹n 3 phÇn mét, gi¶i quyÕt víi mét kÕ ho¹ch bæ sung cho ACARS [EAT8] vµ b¸o c¸o giai ®o¹n 3 phÇn hai víi gi¶i quyÕt phÇn bæ sung tÝnh kh¶ thi cña m¹ng con d÷ liÖu Air/Ground nhËn biÕt bëi giai ®o¹n 2 cña nghiªn cøu ST15.

3.5 Analysis and Conclusions Ph©n tÝch vµ kÕt luËn The ST15 study scope and results to date are considered to be directly applicable to this WP. This conclusion is further reinforced by the fact that both the ST15 study and ACCESS WP202 have been based on the ODIAC defined air/ground data link services with respect to the identification of air/ground communications service requirements. Of key interest to this Work Package are the ST15 conclusions of Phase 2, i.e.: VDL Mode 2 as the primary air/ground subnetwork to be deployed in the ECAC area; VDL Mode 4 (STDMA), Mode S and/or SATCOM as possible back-up or complementary options to the primary VDL Mode 2 subnetwork. Ph¹m vi nghiªn cøu ST15 vµ kÕt qu¶ x¸c nhËn ®a ra ¸p dông trùc tiÕp ®Õn WP nµy. KÕt luËn nµy ®îc t¨ng cêng thªm bëi trªn thùc tÕ lµ c¶ hai nghiªn cøu cña ST15 vµ ACCESS WP202 ®Òu dùa trªn ODIAC ®Þnh nghÜa c¸c dÞch vô ®êng liªn kÕt d÷ liÖu air/ground víi sù thõa nhËn ®Ó nhËn biÕt nhu cÇu dÞch vô truyÒn dÉn air/ground.

Ch×a kho¸ quan träng ®Ó Work Package are the ST15 nµy kÕt luËn trong giai ®o¹n 2 nh sau:

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VDL Mode 2 Nh m¹ng con s¬ cÊp air/ground ®Ó ph¸t triÓn trong vïng ECAC VDL Mode 4 (STDMA), Mode S and/or SATCOM Cã thÓ quay l¹i hoÆc bæ sung sù lùa chän cho m¹ng con s¬ cÊp VDL Mode 2

The results of the ST15 Phase 3 study were presented to the COM Team at the COMT-11 meeting held in Brussels (10-11/2/98). COMT endorsed the ST15 report and recommended “ to implement in the ECAC States the VDL Mode 2 system, as the first ATN air-ground subnetwork, to support initial ATS and Airline data link services” [EAT20]. The COMT also made recommendations regarding the use of other air-ground subnetworks e.g. Mode-S, SATCOM and VDL Mode 4. In particular “to include, inside the EATCHIP Communication Work Program, complementary activities relating to: The definition or selection of the QoS requirements that will be representative of future Air/Ground datalink services; The availability of necessary standards; To assess the ability of VDL Mode 4 to fulfil these requirements; and if the assessment is positive to: develop the operating concept of VDL Mode 4 conduct a safety analysis for VDL Mode 4. To continue to monitor VDL Mode 3 developments and assess its capabilities as appropriate.” [EAT 20] KÕt qu¶ cña ST15 giai ®o¹n 3 nghiªn cøu ®· ®îc nhãm COM tr×nh bµy t¹i cuéc häp COM-11 ë Brussels (10-11/2/98). COMT chøng thùc b¶n b¸o c¸o cña ST15 vµ giíi thiÖu “®Ó thùc thi trong tr¹ng th¸i hÖ thèng VDL Mode 2, nh subnetwork ATN air-ground ®Çu tiªn, hç trî ban ®Çu cho ATS vµ c¸c dÞch vô ®êng liªn kÕt d÷ liÖu hµng kh«ng” [EAT20]. The COMT còng giíi thiÖu sö dông c¸c air-ground subnetworks kh¸c ch¼ng h¹n nh Mode-S, SATCOM and VDL Mode 4. Chi tiÕt trong “®Ó bao gåm, phÇn trong ch¬ng tr×nh truyÒn th«ng the EATCHIP , bæ sung ho¹t ®éng ®Ó :

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®Þnh nghÜa hoÆc lùa chän nh÷ng ®iÒu kiÖn cña QoS ®iÒu ®ã sÏ ®îc thÓ hiÖn ë ®Æc tÝnh c¸c dÞch vô ®êng liªn kÕt d÷ liÖu Air/Ground.

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TÝnh hiÖu lùc cña c¸c chuÈn cÇn thiÕt

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®¸nh gi¸ n¨ng lùc cña VDL Mode 4 ®Ó hoµn thµnh c¸c ®iÒu kiÖn nµy; vµ nÕu sù ®¸nh gi¸ ®îc kh¼ng ®Þnh

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ph¸t triÓn kh¸i niÖm ho¹t ®éng cña VDL Mode 4

híng dÉn mét ph©n tÝch tÝnh an toµn cña VDL Mode 4 §Ó tiÕp tôc gi¸m s¸t sù ph¸t triÓn VDL Mode 3 vµ ®¸nh gi¸ kh¶ n¨ng nã thÝch hîp ” [EAT 20]