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Lochin, Ed. 5 Expires: October 16, 2020 ENAC 6 April 14, 2020 8 Network coding for satellite systems 9 draft-irtf-nwcrg-network-coding-satellites-12 11 Abstract 13 This document is the product of the Coding for Efficient Network 14 Communications Research Group (NWCRG). It conforms to the directions 15 found in the NWCRG taxonomy [RFC8406]. Thus, the scope of the 16 document is network coding as a linear combination of packets in and 17 above the network layer. Physical and MAC layer coding are beyond 18 the scope of the document. The document focuses on a multi-gateway 19 satellite system and identifies the use-cases where network coding 20 provides significant performance improvements. The objective is to 21 contribute to a larger deployment of network coding techniques in and 22 above the network layer in satellite communication systems. These 23 systems generally exploit PHY layer loss recovery mechanisms. The 24 document also identifies open research issues related to the 25 deployment of network coding in satellite communication systems. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on October 16, 2020. 44 Copyright Notice 46 Copyright (c) 2020 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. A Note on Satellite Networks Topology . . . . . . . . . . . . 3 63 3. Use-cases for Improving SATCOM System Performance Using 64 Network Coding . . . . . . . . . . . . . . . . . . . . . . . 5 65 3.1. Two-way Relay Channel Mode . . . . . . . . . . . . . . . 5 66 3.2. Reliable Multicast . . . . . . . . . . . . . . . . . . . 5 67 3.3. Hybrid Access . . . . . . . . . . . . . . . . . . . . . . 6 68 3.4. LAN Packet Losses . . . . . . . . . . . . . . . . . . . . 7 69 3.5. Varying Channel Conditions . . . . . . . . . . . . . . . 8 70 3.6. Improving Gateway Handover . . . . . . . . . . . . . . . 8 71 4. Research Challenges . . . . . . . . . . . . . . . . . . . . . 9 72 4.1. Joint-use of Network Coding and Congestion Control in 73 SATCOM Systems . . . . . . . . . . . . . . . . . . . . . 9 74 4.2. Efficient Use of Satellite Resources . . . . . . . . . . 10 75 4.3. Interaction with Virtualized Satellite Gateways and 76 Terminals . . . . . . . . . . . . . . . . . . . . . . . . 10 77 4.4. Delay/Disruption Tolerant Networks . . . . . . . . . . . 10 78 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 11 79 6. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . 11 80 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 81 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 82 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 83 10. Informative References . . . . . . . . . . . . . . . . . . . 13 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 86 1. Introduction 88 This document is the product of and represents the collaborative work 89 and consensus of the Coding for Efficient Network Communications 90 Research Group (NWCRG); while it is not an IETF product and not a 91 standard it intends to inform the SATellite COMmunication (SATCOM) 92 and Internet research communities about recent developments in 93 Network Coding. A glossary is proposed in Section 6 to clarify the 94 terminology use throughout the document. 96 As will be shown in this document, the implementation of network 97 coding techniques above the network layer of the ISO model, at 98 application or transport layers, offers an opportunity for improving 99 the end-to-end performance of SATCOM systems. While physical- and 100 link-layer coding error protection is usually enough to provide 101 Quasi-Error Free transmission thus minimizing packet loss, when 102 residual errors at those layers cause packet losses, retransmissions 103 add significant delays (in particular in geostationary system with 104 over 0.7 second round-trip delays). Hence the use of network coding 105 at the upper layers can improve the quality of service in SATCOM 106 subnetworks and eventually favorably impact the experience of end 107 users. 109 While there is an active research Community working on network coding 110 techniques above the network layer in general and in SATCOM in 111 particular, not much of this work made it to commercial systems in 112 the satellite industry. In this context, this document aims at 113 identifying opportunities for further usage of network coding in 114 commercial SATCOM networks. 116 The notation used in this document is based on the NWCRG taxonomy 117 [RFC8406]: 119 o Channel and link error correcting codes are considered part of the 120 PHY layer error protection and are out of the scope of this 121 document. 123 o FEC (also called Application-Level FEC) operates in and above the 124 network layer and targets packet loss recovery. 126 o This document considers only coding (or coding techniques or 127 coding schemes) that use a linear combination of packets and 128 excludes for example content coding (e.g., to compress a video 129 flow) or other non-linear operation. 131 2. A Note on Satellite Networks Topology 133 There are multiple SATCOM systems, for example broadcast TV, point to 134 point communication or IoT and monitoring. Therefore, depending on 135 the purpose of the system, the associated ground segments 136 architecture will be different. This section focuses on a satellite 137 system that follows the ETSI DVB standards to provide broadband 138 Internet access via ground-based gateways [ETSIEN2014]. One must 139 note that the overall data capacity of one satellite may be higher 140 than the capacity that one single gateway supports. Hence, there are 141 usually multiple gateways for one unique satellite platform. 143 In this context, Figure 1 shows an example of a multi-gateway 144 satellite system. More information on a generic SATCOM ground 145 segment architecture for bidirectional Internet access can be found 146 in [SAT2017]. 148 +--------------------------+ 149 | application servers | 150 | (data, coding, multicast)| 151 +--------------------------+ 152 | ... | 153 ----------------------------------- 154 | | | | | | 155 +--------------------+ +--------------------+ 156 | network function | | network function | 157 |(firewall, PEP, etc)| |(firewall, PEP, etc)| 158 +--------------------+ +--------------------+ 159 | ... | IP packets | ... | 160 --- 161 +------------------+ +------------------+ | 162 | access gateway | | access gateway | | 163 +------------------+ +------------------+ | 164 | BBFRAME | | gateway 165 +------------------+ +------------------+ | 166 | physical gateway | | physical gateway | | 167 +------------------+ +------------------+ | 168 --- 169 | PLFRAME | 170 +------------------+ +------------------+ 171 | outdoor unit | | outdoor unit | 172 +------------------+ +------------------+ 173 | satellite link | 174 +------------------+ +------------------+ 175 | outdoor unit | | outdoor unit | 176 +------------------+ +------------------+ 177 | | 178 +------------------+ +------------------+ 179 | sat terminals | | sat terminals | 180 +------------------+ +------------------+ 181 | | | | 182 +----------+ | +----------+ | 183 |end user 1| | |end user 3| | 184 +----------+ | +----------+ | 185 +----------+ +----------+ 186 |end user 2| |end user 4| 187 +----------+ +----------+ 189 Figure 1: Data plane functions in a generic satellite multi-gateway 190 system. More details can be found in DVB standard documents. 192 3. Use-cases for Improving SATCOM System Performance Using Network 193 Coding 195 This section details use-cases where network coding techniques could 196 improve SATCOM system performance. 198 3.1. Two-way Relay Channel Mode 200 This use-case considers two-way communication between end-users, 201 through a satellite link as seen in Figure 2. 203 Satellite terminal A sends a packet flow A and satellite terminal B 204 sends a packet flow B to a coding server. The coding server then 205 sends a combination of both flows instead of each individual flows. 206 This results in non-negligible capacity savings that has been 207 demonstrated in the past [ASMS2010]. In the example, a dedicated 208 coding server is introduced (note that its location could be 209 different based on deployment use-case). The network coding 210 operations could also be done at the satellite level, although this 211 would require a lot of computational resource on-board and may not be 212 supported by today's satellites. 214 -X}- : traffic from satellite terminal X to the server 215 ={X+Y= : traffic from X and Y combined sent from 216 the server to terminals X and Y 218 +-----------+ +-----+ 219 |Sat term A |--A}-+ | | 220 +-----------+ | | | +---------+ +------+ 221 ^^ +--| |--A}--| |--A}--|Coding| 222 || | SAT |--B}--| Gateway |--B}--|Server| 223 ===={A+B=========| |={A+B=| |={A+B=| | 224 || | | +---------+ +------+ 225 vv +--| | 226 +-----------+ | | | 227 |Sat term B |--B}-+ | | 228 +-----------+ +-----+ 230 Figure 2: Network Architecture for Two-way Relay Channel using NC 232 3.2. Reliable Multicast 234 The use of multicast servers is one way to better utilize satellite 235 broadcast capabilities. Multicast is proposed in the SHINE ESA 236 project [I-D.vazquez-nfvrg-netcod-function-virtualization] [SHINE]. 237 This use-case considers adding redundancy to a multicast flow 238 depending on what has been received by different end-users, resulting 239 in non-negligible savings of the scarce SATCOM resources. This 240 scenario is shown in Figure 3. 242 -Li}- : packet indicating the loss of packet i of a multicast flow M 243 ={M== : multicast flow including the missing packets 245 +-----------+ +-----+ 246 |Sat term A |-Li}-+ | | 247 +-----------+ | | | +---------+ +------+ 248 ^^ +-| |-Li}--| | |Multi | 249 || | SAT |-Lj}--| Gateway |--|Cast | 250 ===={M==========| |={M===| | |Server| 251 || | | +---------+ +------+ 252 vv +-| | 253 +-----------+ | | | 254 |Sat term B |-Lj}-+ | | 255 +-----------+ +-----+ 257 Figure 3: Network Architecture for a Reliable Multicast using NC 259 A multicast flow (M) is forwarded to both satellite terminals A and 260 B. However packet Ni (respectively Nj) gets lost at terminal A 261 (respectively B), and terminal A (respectively B) returns a negative 262 acknowledgment Li (respectively Lj), indicating that the packet is 263 missing. Using NC, either the access gateway or the multicast server 264 can include a repair packet (rather than the individual Ni and Nj 265 packets) in the multicast flow to let both terminals recover from 266 losses. 268 This could also be achieved by using other multicast or broadcast 269 systems, such as NACK-Oriented Reliable Multicast (NORM) [RFC5740] or 270 File Delivery over Unidirectional Transport (FLUTE) [RFC6726]. Both 271 NORM and FLUTE are limited to block coding, none of them supporting 272 more flexible sliding window encoding schemes that allow decoding 273 before receiving the whole block an added delay benefit 274 [RFC8406][RFC8681]. 276 3.3. Hybrid Access 278 This use-case considers improving multiple path communications with 279 network coding at the transport layer (see Figure 4). This use-case 280 is inspired by the Broadband Access via Integrated Terrestrial 281 Satellite Systems (BATS) project and has been published as an ETSI 282 Technical Report [ETSITR2017]. 284 To cope with packet loss (due to either end-user mobility or 285 physical-layer residual errors), network coding can be introduced 286 both at the CPE and at the concentrator. Apart from packet losses, 287 other gains from this approach include a better tolerance to out-of- 288 order packet delivery which occur when exploited links exhibit high 289 asymmetry in terms of RTT. Depending on the ground architecture 290 [I-D.chin-nfvrg-cloud-5g-core-structure-yang] [SAT2017], some ground 291 equipment might be hosting both SATCOM and cellular network 292 functionality. 294 -{}- : bidirectional link 296 +---+ +--------------+ 297 +-{}-|SAT|-{}-|BACKBONE | 298 +----+ +---+ | +---+ |+------------+| 299 |End |-{}-|CPE|-{}-| ||CONCENTRATOR|| 300 |User| +---+ | +---+ |+------------+| +-----------+ 301 +----+ |-{}-|DSL|-{}-| |-{}-|Application| 302 | +---+ | | |Server | 303 | | | +-----------+ 304 | +---+ | | 305 +-{}-|LTE|-{}-+--------------+ 306 +---+ 308 Figure 4: Network Architecture for a Hybrid Access Using Network 309 Coding 311 3.4. LAN Packet Losses 313 This use-case considers using network coding in the scenario where a 314 lossy WIFI link is used to connect to the SATCOM network. When 315 encrypted end-to-end applications based on UDP are used, a 316 Performance Enhancing Proxy (PEP) cannot operate hence other 317 mechanism need to be used. The WIFI packet losses will result in an 318 end-to-end retransmission that will harm the end-user quality of 319 experience and poorly utilize SATCOM bottleneck resource for non- 320 revenue generating traffic. In this use-case, adding network coding 321 techniques will prevent the end-to-end retransmission from occurring 322 since the packet losses would probably recovered. 324 The architecture is shown in Figure 5. 326 -{}- : bidirectional link 327 -''- : Wi-Fi link 328 C : where network coding techniques could be introduced 330 +----+ +--------+ +---+ +-------+ +-------+ +--------+ 331 |End | |Sat. | |SAT| |Phy | |Access | |Network | 332 |user|-''-|Terminal|-{}-| |-{}-|Gateway|-{}-|Gateway|-{}-|Function| 333 +----+ +--------+ +---+ +-------+ +-------+ +--------+ 334 C C C C 336 Figure 5: Network Architecture for dealing with LAN Losses 338 3.5. Varying Channel Conditions 340 This use-case considers the usage of network coding to cope with sub 341 second physical channel condition changes where the physical-layer 342 mechanisms (Adaptive Coding and Modulation (ACM)) may not adapt the 343 modulation and error-correction coding in time: the residual errors 344 lead to higher layer packet losses that can be recovered with network 345 coding. This use-case is mostly relevant when mobile users are 346 considered or when the satellite frequency band introduces quick 347 changes in channel condition (Q/V bands, Ka band, etc.). Depending 348 on the use-case (e.g., very high frequency bands, mobile users) or 349 depending on the deployment use-cases (e.g., performance of the 350 network between each individual data block), the relevance of adding 351 network coding is different. 353 The system architecture is shown in Figure 6. 355 -{}- : bidirectional link 356 C : where network coding techniques could be introduced 358 +---------+ +---+ +--------+ +-------+ +--------+ 359 |Satellite| |SAT| |Physical| |Access | |Network | 360 |Terminal |-{}-| |-{}-|Gateway |-{}-|Gateway|-{}-|Function| 361 +---------+ +---+ +--------+ +-------+ +--------+ 362 C C C C 364 Figure 6: Network Architecture for dealing with Varying Link 365 Characteristics 367 3.6. Improving Gateway Handover 369 This use-case considers the recovery of packets that may be lost 370 during gateway handover. Whether for off-loading a given equipment 371 or because the transmission quality differs from gateway to gateway, 372 switching the transmission gateway may be beneficial. However, 373 packet losses can occur if the gateways are not properly synchronized 374 or if the algorithm used to trigger gateway handover is not properly 375 tuned. During these critical phases, network coding can be added to 376 improve the reliability of the transmission and allow a seamless 377 gateway handover. 379 Figure 7 illustrates this use-case. 381 -{}- : bidirectional link 382 ! : management interface 383 C : where network coding techniques could be introduced 384 C C 385 +--------+ +-------+ +--------+ 386 |Physical| |Access | |Network | 387 +-{}-|gateway |-{}-|gateway|-{}-|function| 388 | +--------+ +-------+ +--------+ 389 | ! ! 390 +---------+ +---+ +---------------+ 391 |Satellite| |SAT| | Control plane | 392 |Terminal |-{}-| | | manager | 393 +---------+ +---+ +---------------+ 394 | ! ! 395 | +--------+ +-------+ +--------+ 396 +-{}-|Physical|-{}-|Access |-{}-|Network | 397 |gateway | |gateway| |function| 398 +--------+ +-------+ +--------+ 399 C C 401 Figure 7: Network Architecture for dealing with Gateway Handover 403 4. Research Challenges 405 This section proposes a few potential approaches to introduce and use 406 network coding in SATCOM systems. 408 4.1. Joint-use of Network Coding and Congestion Control in SATCOM 409 Systems 411 Many SATCOM systems typically use Performance Enhancing Proxy (PEP) 412 RFC 3135 [RFC3135]. PEPs usually split end-to-end connections and 413 forward transport or application layer packets to the satellite 414 baseband gateway that deals with layer-2 and layer-1 encapsulation. 415 PEPs contribute to mitigate congestion in a SATCOM systems by 416 limiting the impact of long delays on Internet protocols. A PEP 417 mechanism could also include network coding operation and thus 418 support the use-cases that have been discussed in the Section 3 of 419 this document. 421 Deploying network coding in the PEP could be relevant and be 422 independent from the specifics of a SATCOM link. This however leads 423 to research questions dealing with the potential interaction between 424 network coding and congestion control. This is discussed in 425 [I-D.irtf-nwcrg-coding-and-congestion] 427 4.2. Efficient Use of Satellite Resources 429 There is a recurrent trade-off in SATCOM systems: how much overhead 430 from redundant reliability packets can be introduced to guarantee a 431 better end-user QoE while optimizing capacity usage ? At which layer 432 this supplementary redundancy should be added ? 434 This problem has been tackled in the past by the deployment of 435 physical-layer error-correction codes, but there remains questions on 436 adapting the coding overhead and added delay for, e.g., the quickly 437 varying channel conditions use-case where ACM may not be reacting 438 quickly enough as was discussed in Section 3.5. 440 4.3. Interaction with Virtualized Satellite Gateways and Terminals 442 In the emerging virtualized network infrastructure, network coding 443 could be easily deployed as a Virtual Network Functions (VNF). The 444 next generation of SATCOM ground segments will rely on a virtualized 445 environment to integrate to terrestrial networks. This trend towards 446 Network Function Virtualization (NFV) is also central to 5G and next 447 generation cellular networks, making this research applicable to 448 other deployment scenarios 449 [I-D.chin-nfvrg-cloud-5g-core-structure-yang]. As one example, the 450 network coding VNF deployment in a virtualized environment has been 451 presented in [I-D.vazquez-nfvrg-netcod-function-virtualization]. 453 A research challenge would be the optimization of the NFV service 454 function chaining, considering a virtualized infrastructure and other 455 SATCOM specific functions, in order to guarantee efficient radio-link 456 usage and provide easy-to-deploy SATCOM services. Moreover, another 457 challenge related to a virtualized SATCOM equipment is the management 458 of limited buffered capacities in large gateways. 460 4.4. Delay/Disruption Tolerant Networks 462 Communications among deep-space platforms and terrestrial gateways 463 can be a challenge. Reliable end-to-end (E2E) communications over 464 such paths must cope with very long delays and frequent link 465 disruptions; indeed, E2E connectivity may be available only 466 intermittently. Delay/Disruption Tolerant Networking [RFC4838] is a 467 solution to enable reliable internetworking space communications 468 where both standard ad-hoc routing and E2E Internet protocols cannot 469 be used. Moreover, DTN can also be seen as an alternative solution 470 to transfer data between a central PEP and a remote PEP. 472 Network Coding enables E2E reliable communications over a DTN with 473 potential adaptive re-encoding, as proposed in [THAI15]. Here, the 474 use-cases proposed in Section 3.5 would legitimize the usage of 475 network coding within the DTN stack to improve the physical channel 476 utilization and minimize the effects of the E2E transmission delays. 477 In this context, the use of packet erasure coding techniques inside a 478 Consultative Committee for Space Data Systems (CCSDS) architecture 479 has been specified in [CCSDS-131.5-O-1]. One research challenge 480 remains on how such network coding can be integrated in the IETF DTN 481 stack. 483 5. Conclusion 485 This document introduces some wide-scale network coding techniques 486 opportunities in satellite telecommunications systems. 488 Even though this document focuses on satellite systems, it is worth 489 pointing out that some scenarios proposed here may be relevant to 490 other wireless telecommunication systems. As one example, the 491 generic architecture proposed in Figure 1 may be mapped onto cellular 492 networks as follows: the 'network function' block gathers some of the 493 functions of the Evolved Packet Core subsystem, while the 'access 494 gateway' and 'physical gateway' blocks gather the same type of 495 functions as the Universal Mobile Terrestrial Radio Access Network. 496 This mapping extends the opportunities identified in this document 497 since they may also be relevant for cellular networks. 499 6. Glossary 501 The glossary of this memo extends the glossary of the taxonomy 502 document [RFC8406] as follows: 504 o ACM : Adaptive Coding and Modulation; 506 o BBFRAME: Base-Band FRAME - satellite communication layer 2 507 encapsulation work as follows: (1) each layer 3 packet is 508 encapsulated with a Generic Stream Encapsulation (GSE) mechanism, 509 (2) GSE packets are gathered to create BBFRAMEs, (3) BBFRAMEs 510 contain information related to how they have to be modulated (4) 511 BBFRAMEs are forwarded to the physical-layer; 513 o CPE: Customer Premises Equipment; 515 o COM: COMmunication; 516 o DSL: Digital Subscriber Line; 518 o DTN: Delay/Disruption Tolerant Network; 520 o DVB: Digital Video Broadcasting; 522 o E2E: End-to-end; 524 o ETSI: European Telecommunications Standards Institute; 526 o FEC: Forward Erasure Correction; 528 o FLUTE: File Delivery over Unidirectional Transport; 530 o IntraF: Intra-Flow Coding; 532 o InterF: Inter-Flow Coding; 534 o IoT: Internet of Things; 536 o LTE: Long Term Evolution; 538 o MPC: Multi-Path Coding; 540 o NC: Network Coding; 542 o NFV: Network Function Virtualization - concept of running 543 software-defined network functions; 545 o NORM: NACK-Oriented Reliable Multicast; 547 o PEP: Performance Enhancing Proxy [RFC3135] - a typical PEP for 548 satellite communications include compression, caching and TCP 549 acceleration; 551 o PLFRAME: Physical Layer FRAME - modulated version of a BBFRAME 552 with additional information (e.g., related to synchronization); 554 o QEF: Quasi-Error-Free; 556 o QoE: Quality-of-Experience; 558 o QoS: Quality-of-Service; 560 o SAT: SATellite; 562 o SATCOM: generic term related to all kinds of SATellite 563 COMmunication systems; 565 o SPC: Single-Path Coding; 567 o VNF: Virtual Network Function - implementation of a network 568 function using software. 570 7. Acknowledgements 572 Many thanks to John Border, Stuart Card, Tomaso de Cola, Vincent 573 Roca, Lloyd Wood and Marie-Jose Montpetit for their help in writing 574 this document. 576 8. IANA Considerations 578 This memo includes no request to IANA. 580 9. Security Considerations 582 Security considerations are inherent to any access network, and in 583 particular SATCOM systems. The use of FEC or Network Coding in 584 SATCOM also comes with risks (e.g., a single corrupted redundant 585 packet may propagate to several flows when they are protected 586 together in an Inter-Flow coding approach, see section Section 3). 587 However, this is not specific to the SATCOM use-case and this 588 document does not further elaborate on it. 590 10. Informative References 592 [ASMS2010] 593 De Cola, T. and et. al., "Demonstration at opening session 594 of ASMS 2010", Advanced Satellite Multimedia Systems 595 (ASMS) Conference , 2010. 597 [CCSDS-131.5-O-1] 598 "Erasure correcting codes for use in near-earth and deep- 599 space communications", CCSDS Experimental 600 specification 131.5-0-1, 2014. 602 [ETSIEN2014] 603 "Digital Video Broadcasting (DVB); Second Generation DVB 604 Interactive Satellite System (DVB-RCS2); Part 2: Lower 605 Layers for Satellite standard", ETSI EN 301 545-2, 2014. 607 [ETSITR2017] 608 "Satellite Earth Stations and Systems (SES); Multi-link 609 routing scheme in hybrid access network with heterogeneous 610 links", ETSI TR 103 351, 2017. 612 [I-D.chin-nfvrg-cloud-5g-core-structure-yang] 613 Chen, C. and Z. Pan, "Yang Data Model for Cloud Native 5G 614 Core structure", draft-chin-nfvrg-cloud-5g-core-structure- 615 yang-00 (work in progress), December 2017. 617 [I-D.irtf-nwcrg-coding-and-congestion] 618 Kuhn, N., Lochin, E., Michel, F., and M. Welzl, "Coding 619 and congestion control in transport", draft-irtf-nwcrg- 620 coding-and-congestion-02 (work in progress), March 2020. 622 [I-D.vazquez-nfvrg-netcod-function-virtualization] 623 Vazquez-Castro, M., Do-Duy, T., Romano, S., and A. Tulino, 624 "Network Coding Function Virtualization", draft-vazquez- 625 nfvrg-netcod-function-virtualization-02 (work in 626 progress), November 2017. 628 [RFC3135] Border, J., Kojo, M., Griner, J., Montenegro, G., and Z. 629 Shelby, "Performance Enhancing Proxies Intended to 630 Mitigate Link-Related Degradations", RFC 3135, 631 DOI 10.17487/RFC3135, June 2001, 632 . 634 [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, 635 R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant 636 Networking Architecture", RFC 4838, DOI 10.17487/RFC4838, 637 April 2007, . 639 [RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker, 640 "NACK-Oriented Reliable Multicast (NORM) Transport 641 Protocol", RFC 5740, DOI 10.17487/RFC5740, November 2009, 642 . 644 [RFC6726] Paila, T., Walsh, R., Luby, M., Roca, V., and R. Lehtonen, 645 "FLUTE - File Delivery over Unidirectional Transport", 646 RFC 6726, DOI 10.17487/RFC6726, November 2012, 647 . 649 [RFC8406] Adamson, B., Adjih, C., Bilbao, J., Firoiu, V., Fitzek, 650 F., Ghanem, S., Lochin, E., Masucci, A., Montpetit, M-J., 651 Pedersen, M., Peralta, G., Roca, V., Ed., Saxena, P., and 652 S. Sivakumar, "Taxonomy of Coding Techniques for Efficient 653 Network Communications", RFC 8406, DOI 10.17487/RFC8406, 654 June 2018, . 656 [RFC8681] Roca, V. and B. Teibi, "Sliding Window Random Linear Code 657 (RLC) Forward Erasure Correction (FEC) Schemes for 658 FECFRAME", RFC 8681, DOI 10.17487/RFC8681, January 2020, 659 . 661 [SAT2017] Ahmed, T., Dubois, E., Dupe, JB., Ferrus, R., Gelard, P., 662 and N. Kuhn, "Software-defined satellite cloud RAN", 663 International Journal on Satellite Communnications and 664 Networking vol. 36 - https://doi.org/10.1002/sat.1206, 665 2017. 667 [SHINE] Pietro Romano, S. and et. al., "Secure Hybrid In Network 668 caching Environment (SHINE) ESA project", ESA project , 669 2017 on-going. 671 [THAI15] Thai, T., Chaganti, V., Lochin, E., Lacan, J., Dubois, E., 672 and P. Gelard, "Enabling E2E reliable communications with 673 adaptive re-encoding over delay tolerant networks", 674 Proceedings of the IEEE International Conference on 675 Communications http://dx.doi.org/10.1109/ICC.2015.7248441, 676 June 2015. 678 Authors' Addresses 680 Nicolas Kuhn (editor) 681 CNES 682 18 Avenue Edouard Belin 683 Toulouse 31400 684 France 686 Email: nicolas.kuhn@cnes.fr 688 Emmanuel Lochin (editor) 689 ENAC 690 10 Avenue Edouard Belin 691 Toulouse 31400 692 France 694 Email: emmanuel.lochin@enac.fr