Internet DRAFT - draft-draft-li-istn-addressing-requirement
draft-draft-li-istn-addressing-requirement
Internet Engineering Task Force Y. Li
Internet-Draft H. Li
Intended status: Informational J. Liu
Expires: 28 April 2022 Tsinghua University
25 October 2021
Problems and Requirements of Addressing in Integrated Space-Terrestrial
Network
draft-li-istn-addressing-requirement-00
Abstract
This document presents a detailed analysis of the problems and
requirements of network addressing in "Internet in space" for
terrestrial users. It introduces the basics of satellite mega-
constellations, terrestrial terminals/ground stations, and their
inter-networking. Then it explicitly analyzes how space-terrestrial
mobility yeilds challenges for the logical topology, addressing, and
their impact on routing. The requirements of addressing in the
space-terrestrial network are discussed in detail, including
uniqueness, stability, locality, scalability, efficiency and backward
compatibility with terrestrial Internet. The problems and
requirements of network addressing in space-terrestrial networks are
finally outlined.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
Li, et al. Expires 28 April 2022 [Page 1]
Internet-Draft Problems and Requirements of Addressing October 2021
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Basics of Space-Terrestrial Network . . . . . . . . . . . . . 3
3.1. Space Segment . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Ground Segment . . . . . . . . . . . . . . . . . . . . . 5
3.3. Space-Ground Internetworking . . . . . . . . . . . . . . 6
4. Problems in Space-Terrestrial Network Addressing . . . . . . 7
4.1. Unstable Space-Terrestrial Topology . . . . . . . . . . . 7
4.2. Inconsistent "Locations" for Space/Terrestrial Nodes . . 8
4.3. Impact on Routing: Frequent Routing Updates . . . . . . . 9
5. Requirements of Addressing in Space-Terrestrial Network . . . 10
5.1. Uniqueness . . . . . . . . . . . . . . . . . . . . . . . 10
5.2. Stability . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3. Locality . . . . . . . . . . . . . . . . . . . . . . . . 11
5.4. Scalability . . . . . . . . . . . . . . . . . . . . . . . 11
5.5. Efficiency . . . . . . . . . . . . . . . . . . . . . . . 11
5.6. Backward Compatibility with Terrestrial Internet . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The future Internet is up in the sky. We have seen a rocket-fast
deployment of mega-constellations with 100s-10,000s of low-earth-
orbit (LEO) satellites, such as Starlink [STARLINK], Kuiper [KUIPER]
and OneWeb [ONEWEB]. These constellations promise competitive low
latency and high capacity to terrestrial networks. They expand
global high-speed Internet to remote areas that were not reachable by
terrestrial networks, resulting in a tens-of-billions-of-dollar
market with 3.7 billion users in rural areas[ITU-Measure], developing
countries, aircraft, or oceans.
Li, et al. Expires 28 April 2022 [Page 2]
Internet-Draft Problems and Requirements of Addressing October 2021
A salient feature for LEO mega-constellations is their high relative
motions to the rotating earth. Unlike geosynchronous satellite or
terrestrial networks, each LEO satellite moves fast (e.g., 28,080 km/
h for Starlink), causing short-lived coverage for terrestrial users
(less than 3 minutes). This yields diverse challenges for the
traditional network designs.
This memo outlines the problems and requirements of addressing in
integrated space-terrestrial network. It starts with the basics of
satellite mega-constellations, terrestrial ground stations/terminals,
and their inter-networking. It analyzes how high space-terrestrial
relative motions yields challenges for logical topology, addressing
and their impacts on routing. Then it discusses the requirements of
network addressing in space-terrestrial network for uniqueness,
stability, locality, scalability, efficiency and backward
compatibility with terrestrial Internet.
2. Terminology
GSO: Geosynchronous orbit (at the altitude of 35,786 km).
NGSO: Non-geosynchronous orbit.
LEO: Low Earth Orbit (at the altitude of 180-2,000 km).
MEO: Medium Earth Orbit (at the altitude of 180-35,786 km).
ISL: Inter Satellite Link.
NAT: Network Address Translation.
GS: Ground Station, a device on ground connecting the satellite.
FIB: Forwarding Information Base.
3. Basics of Space-Terrestrial Network
As shown in Figure 1, a space-terrestrial network for terrestrial
users consists of the space segment and ground segment. The space
segment includes the satellite or constellation. The ground segment
comprises satellite terminals and ground stations.
Li, et al. Expires 28 April 2022 [Page 3]
Internet-Draft Problems and Requirements of Addressing October 2021
3.1. Space Segment
Satellites can be classified based on their relative motions to the
earth. A satellite can operate at the geosynchronous orbit (GSO, at
about 35,786 km altitude) or non-geosynchronous orbits, such as low
earth orbits (LEO, <=2,000km) and medium earth orbits (MEO, between
2,000 km and 35,786 km). Satellites at higher altitudes offer
broader coverage, while satellites at lower altitudes move faster.
Historically, communications in space were dominated by GSO
satellites. As shown in Table 1, GSO offers excellent coverage at
high altitudes, but at the cost of long space-terrestrial RTT
(>=200ms) and low bandwidth (<=10Mbps, due to bit errors in long
distance transmission). Instead, recent efforts seek to adopt
satellites at lower non-geosynchronous orbits, with a special
interest in low-earth orbits. Together with Ku (12-18 GHz) and Ka
(26.5-40GHz) bands, these satellites promise competitive bandwidth
and latency to terrestrial networks( [LOWLATENCY-ROUTING-SPACE],
[SPACE-RACE], [NETWORK-TOPO-DESIGN]). Due to low coverage for each
LEO satellite, a mega-constellation is necessary to retain global
coverage. Table 2 exemplifies popular LEO mega-costellations in
operation. They are enabled by recent advances in satellite
miniaturization and rocket reusability.
+-----------+ +-----------+
| Satellite |_______ISL_______| Satellite | (Space Segment)
_ _|___________| _ _|___________|
/| \ /|
/ | \ / |
/ (Bent pipe) \ | /
/ _ _\| /
+---------+ +------------+
| Mobile | | Ground |
| Station | | Station | (Ground Segment)
|_________| |____________|
Figure 1: A simplified space-terrestrial network architecture
Li, et al. Expires 28 April 2022 [Page 4]
Internet-Draft Problems and Requirements of Addressing October 2021
+============+===============+==========+
| Orbit | Altitude (km) | RTT (ms) |
+======+=====+===============+==========+
| GSO | GEO | 35,786 | 240 |
+------+-----+---------------+----------+
| NGSO | MEO | 2,000-35,786 | 12-240 |
| +-----+---------------+----------+
| | LEO | 500-2,000 | 2-12 |
+------+-----+---------------+----------+
Table 1: Differences between GSO and
NGSO.
+===============+=================+=============+===============+
| Constellation | Num. satellites | Num. orbits | Altitude (km) |
+===============+=================+=============+===============+
| Starlink | 1584 | 72 | 540/550 |
| +-----------------+-------------+---------------+
| | 720 | 36 | 570 |
| +-----------------+-------------+---------------+
| | 348 | 6 | 560 |
| +-----------------+-------------+---------------+
| | 172 | 4 | 560 |
+---------------+-----------------+-------------+---------------+
| Kuiper | 1156 | 34 | 630 |
| +-----------------+-------------+---------------+
| | 1296 | 36 | 610 |
| +-----------------+-------------+---------------+
| | 784 | 28 | 590 |
+---------------+-----------------+-------------+---------------+
| Telesat | 351 | 27 | 1015 |
| +-----------------+-------------+---------------+
| | 1320 | 40 | 1325 |
+---------------+-----------------+-------------+---------------+
| Iridium | 66 | 6 | 780 |
+---------------+-----------------+-------------+---------------+
Table 2: Low-earth-orbit (LEO) satellite mega-constellations
in operation.
3.2. Ground Segment
Terrestrial users access satellite networks via terminals (e.g.,
satellite phones, onboard dishes, IoT endpoints) or ground stations.
Ground stations can serve as network gateways (e.g., carrier-grade
NAT in Starlink [STARLINK-CGNAT] and Kuiper [KUIPER-CGNAT]) and
remote satellite controllers (e.g., telemetry, tracking, orbital
update commands, or centralized routing control).
Li, et al. Expires 28 April 2022 [Page 5]
Internet-Draft Problems and Requirements of Addressing October 2021
3.3. Space-Ground Internetworking
Early satellite communications favor the simple "bent-pipe-only"
model (Figure 1), i.e., satellites only relay terrestrial users'
radio signals to the fixed ground stations without ISLs or routing.
This model has been popular in GSO satellites with broad coverage (2G
GMR [GEO-MOBILE-RADIO-INTERFACE] [ETSI-TS-101], 3G BGAN [BGAN]
[ETSI-TS-102], and DVB-S [SATELLITE-COMMUNICATIONS]), and recently
adopted by LEO satellites in OneWeb (4G) [ONEWEB] and 5G NTN
[STUDY-NR-SUPPORT] [SOLUTION-NR-NTN]. However, this model suffers
from low LEO satellite coverage. To access the network, both
terrestrial users and ground stations must reside inside the
satellite's coverage. Due to each LEO satellite's low coverage, most
users in remote areas with sparse or no ground stations cannot be
served. As shown in Table 3, under current Starlink (no ISLs so far)
and ground station deployments ([STARLINK-GS-FOUND], [AZURE-GS],
[AWS-GS], [GOOGLE-DATA-CENTER], [AZURE-CLOUD-STARLINK],
[STARLINK-GS-MAP]), 27%-52% global populations cannot be served by
the "bent-pipe-only" model (depending on how many satellites each
ground station can simultaneously associate to). Most under-served
users are from remote areas (e.g., Africa), thus causing revenue loss
for operators. Deploying dense ground stations in these remote areas
could mitigate this. However, it is expensive and lowers commercial
competitive advantages to terrestrial networks.
Instead, modern LEO mega-constellations favor satellite routing to
expand global coverage or enable Internet backbones
[Giuliari20Internet]. To date, inter-satellite links are still under
early adoption([BEIDOU-TEST], [TheVerge-STARLINK-SPEED]). The recent
"burn on re-entry" regulations from FCC also slows down the adoption
of ISLs[SPACEX-CLAIM]. As a near-term remedy, ground station-
assisted routing is currently adopted. There are two variants. The
GS-as-gateway is adopted by Starlink and Kuiper. Each ground station
is a carrier-grade NAT that offers private IP[RFC0791] for
terrestrial users. The GS-as-relay [USE-GROUND-RELAY] mitigates ISLs
with ground station-assisted routing, but is vulnerable to
intermittent space-terrestrial links in Ku/Ka-bands. Like the "bent-
pipe only" model (Figure 1), both heavily rely on ubiquitous ground
station deployments in remote areas and even oceans, thus lowering
competitive edges to terrestrial networks. Instead, we take a
forward-looking view to exploring inter-satellite routing for its
long-term success.
Li, et al. Expires 28 April 2022 [Page 6]
Internet-Draft Problems and Requirements of Addressing October 2021
+=============+======+======+=======+=======+======+========+=======+
| |Global|Africa|Oceania| South | Asia |European| North |
| | | | |America| | |America|
+=============+======+======+=======+=======+======+========+=======+
| 1-SAT |48.71%|19.52%| 42.85%| 49.63%|43.49%| 91.00% | 87.50%|
| assicoation | | | | | | | |
+-------------+------+------+-------+-------+------+--------+-------+
| 2-SAT |57.30%|24.37%| 56.58%| 53.90%|55.91%| 94.33% | 91.23%|
| assicoation | | | | | | | |
+-------------+------+------+-------+-------+------+--------+-------+
| 4-SAT |67.04%|26.13%| 60.31%| 63.16%|71.34%| 95.46% | 95.04%|
| assicoation | | | | | | | |
+-------------+------+------+-------+-------+------+--------+-------+
| 8-SAT |73.04%|29.17%| 60.68%| 65.65%|80.28%| 96.91% | 98.86%|
| assicoation | | | | | | | |
+-------------+------+------+-------+-------+------+--------+-------+
Table 3: Global population that could access Starlink in its
current "bent- pipe-only" model.
4. Problems in Space-Terrestrial Network Addressing
In terrestrial and GEO satellite networks, the logical network
topology, addresses, and routes are mostly stationary due to fixed
infrastructure. Instead, LEO mega-constellations hardly enjoy this
luxury, whose satellites move at high speeds (about 28,080 km/h).
The earth's rotation further complicates the relative motions between
space and ground. In this section, we will analyze how high relative
motion between space and ground challenges addressing due to topology
instability, and its impact on routing[INTERNET-IN-SPACE].
4.1. Unstable Space-Terrestrial Topology
High physical mobility incurs frequent link churns between space and
terrestrial nodes, thus causing frequent logical network topology
changes. For all mega-constellations in Table 2, the topology
changes every 10s of seconds[INTERNET-IN-SPACE]. The link churn
populates with more satellites and ground stations.
In terrestrial mobile networks (e.g., 4G/5G), such physical link
churn can be masked by handoffs without incurring logical topology
changes. This method works based on two premises. First, all link
churns occur at the last-hop radio due to user mobility, without
affecting the infrastructure topology. Second, all cellular
infrastructure nodes are fixed, resulting in a stable logical
topology as "anchors".
Li, et al. Expires 28 April 2022 [Page 7]
Internet-Draft Problems and Requirements of Addressing October 2021
However, neither premise holds in non-geosynchronous constellations.
Instead, infrastructure mobility between satellites and ground
stations becomes a norm rather than an exception. This voids
cellular handoffs' merits to avoid propagation of physical link
churns to logical network topology: They are designed for user
mobility only, and heavily rely on the fixed infrastructure as
"anchors." Therefore, 5G NTN lists satellite handoffs as an unsolved
problem ([STUDY-NR-SUPPORT], [SOLUTION-NR-NTN]), and the latest 3GPP
5G release 17 defers its mobility support for satellites
[TEC-SPECI-GROUP-MEETING] due to significant architectural changes.
While Starlink uses handoffs to migrate physical links between
satellites and ground stations (every 15s [STARLINK-CGNAT]), its
logical topology and routing are still be repeatedly updated at high
costs.
4.2. Inconsistent "Locations" for Space/Terrestrial Nodes
Each space/terrestrial node has two notions of "locations": The
logical location in its topological address, and the physical
location in reality. With repetitive topology changes, a static
network address can hardly ensure its logical location in the
topology is consistent with the fast-moving node's physical location
in reality. Then to correctly forward data, a network should choose
one of the following designs:
a. Dynamic address updates
A node can repetitively re-bind its physical location to its
logical network address, thus incurring frequent address updates
or re-binding. Under high mobility, this could severely disrupt
user experiences or incur heavy signaling overhead. Table 4 and
Table 5 project the address update frequency when using legacy IP
addresses[RFC0791] for logical interfaces. In this scheme, the
terrestrial users' logical IP[RFC0791] address changes if it re-
associates to a new satellite (thus new interfaces and subnets)
to retain its Internet access. Due to high LEO satellite
mobility, each user is forced to change its logical IP
address[RFC0791] every 133-510s. Every second, we observe
2,082-7,961 global users per second should change their IP
addresses.
Li, et al. Expires 28 April 2022 [Page 8]
Internet-Draft Problems and Requirements of Addressing October 2021
+============+============+============+============+
| Starlink | Telesat | Kuiper | Iridium |
+============+============+============+============+
| Every 133s | Every 510s | Every 510s | Every 458s |
+------------+------------+------------+------------+
Table 4: Frequency of each user's logical IP
address update.
+==========+=========+========+=========+
| Starlink | Telesat | Kuiper | Iridium |
+==========+=========+========+=========+
| 7961 | 2082 | 5673 | 2379 |
+----------+---------+--------+---------+
Table 5: Number of terrestrial users
that change logical IP address per
second.
b. Static address binding to a fixed gateway
This is adopted by the cellular networks and Starlink
[STARLINK-CGNAT] and Kuiper's[KUIPER-CGNAT] initial rollouts.
Each user gets a static address from the remote ground station
(via carrier-grade NAT), which masks the external address changes
and redirects users' traffic. This mitigates user address
updates, but cannot avoid gateway's external address updates when
changing satellite interfaces (detailed below). It also incurs
detours and long routing latencies for remote users from ground
stations (e.g., 18,000 km detours and 370 ms extra delays in
[lai2021icnp]).
4.3. Impact on Routing: Frequent Routing Updates
The inconsistent locations in addressing further impact the network
routing. As space and terrestrial infrastructure nodes physically
move fast, the logical routing in cyberspace expires frequently. It
must be updated frequently, thus threatening various routing schemes:
a. Distributed routing: Repetitive re-convergence.
In distributed routing, network nodes distribute topology
information to others, locally compute forwarding tables, and
eventually reach a global consensus on routing paths (i.e.,
convergence). Before global routing convergence, there is no
guaranteed network reachability. With high mobility, each LEO
satellite can only offer very short-lived access for a ground
station(<=3 minutes in Starlink). Frequent topology updates
Li, et al. Expires 28 April 2022 [Page 9]
Internet-Draft Problems and Requirements of Addressing October 2021
cause repetitive routing re-convergence and thus low network
usability. For intra-domain routing (e.g., OSPF[RFC2328], IS-
IS[RFC1142]), most mega-constellations suffer from low network
usability. Even the the size of constellation is samll, the
network needs more than fifty seconds to converge after each
handoff while using OSPF[TIMESLOT-DIVISION]. For inter-domain
routing (e.g., BGP[RFC4271]), [Giuliari20Internet] and
[NETWORK-IN-HEAVEN] show frequent logical topology changes cause
BGP[RFC4271] re-peering, thus sharpening the instability of
global Internet routing.
b. Centralized routing: Repetitive global updates.
In the centralized routing, a ground station predicts the
temporal evolution of topology based on satellites' orbital
patterns, divides it into a series of semi-static topology
snapshots, schedules the forthcoming global routing tables for
each snapshot, and remotely updates the routing tables to all
satellites (e.g., via SDN[RFC7426], MPLS[RFC3031], or
SRv6[RFC8754]). LEO mega-constellations pose stresses on
centralized routing's scalability, stability, and complexity.
Due to frequent link churns, the topology snapshots and FIBs
explode with more satellites, ground stations, and faster
mobility. Moreover, every satellite should locally load these
new FIBs upon snapshot changes, which is vulnerable to transient
global routing inconsistencies and thus black holes or loops.
5. Requirements of Addressing in Space-Terrestrial Network
Except from the basic properties like clusterability, network
addressing in space-terrestrial network should also meet the
following requirements:
5.1. Uniqueness
In integrated space-terrestrial networks, each user's address should
be globally unique. This property calls for address allocation and
duplicate address detection mechanisms.
5.2. Stability
This property ensures that the addressing of each node does not
change with the movement of users or satellites. With this property,
location-based routing will be more stable, avoiding routing
convergence caused by the high dynamics of integrated space-
terrestrial network. It also reduces the frequency of network
addresses updates and reduces the impact on users' network services.
Li, et al. Expires 28 April 2022 [Page 10]
Internet-Draft Problems and Requirements of Addressing October 2021
5.3. Locality
For any two users or satellites, this property ensures that if their
addresses are closer, their actual physical distances should be
closer. It not only guarantees the unified logical and physical
locations, but also simplifies the design and implementation of
location-based routing.
5.4. Scalability
The addressing of integrated space-terrestrial network should be
designed to accommodate as many satellites and terrestrial nodes as
possible. What's more, it should scale to more satellites and
terrestrial users if needed.
5.5. Efficiency
In order to avoid frequent addresses updates, the design of
addressing in space-terrestrial network should not require static
address binding to remote gateways (e.g., carrier-grade NAT). The
addressing method should ensure consistent cyber-physical locations,
thus easing physically shortest paths without detours.
5.6. Backward Compatibility with Terrestrial Internet
To ensure seamless expansion of the global Internet ecosystem, the
addressing in space-terrestrial network should be backward compatible
with terrestrial Internet. It should be compatible the standard IPv6
addressing formats, and facilitates inter-networking to external
networks without modifying terrestrial infrastructure. For backward
compatibility with IPv4, we recommend adopting 4over6 transition for
integrated space-terrestrial networks.
6. IANA Considerations
This memo includes no request to IANA.
7. Security Considerations
The present memo does not introduce any new technology and/or
mechanism and as such does not introduce any security threat to the
TCP/IP protocol suite.
8. References
8.1. Normative References
Li, et al. Expires 28 April 2022 [Page 11]
Internet-Draft Problems and Requirements of Addressing October 2021
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC1142] Oran, D., "OSI IS-IS Intra-domain Routing Protocol",
RFC 1142, DOI 10.17487/RFC1142, February 1990,
<https://www.rfc-editor.org/info/rfc1142>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<https://www.rfc-editor.org/info/rfc2328>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271,
January 2006, <https://www.rfc-editor.org/info/rfc4271>.
[RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
Defined Networking (SDN): Layers and Architecture
Terminology", RFC 7426, DOI 10.17487/RFC7426, January
2015, <https://www.rfc-editor.org/info/rfc7426>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
8.2. Informative References
[AWS-GS] "Amazon AWS Ground station: Easily control satellites and
ingest data with fully managed Ground Station as a
Service, 2021", <https://aws.amazon.com/ground-station/>.
[AZURE-CLOUD-STARLINK]
"CNBC. Microsoft partners with SpaceX to connect Azure
cloud to Musk's Starlink satellite Internet, 2020",
<https://tinyurl.com/ybcwn7ft>.
[AZURE-GS] "Microsoft Azure. New Azure Orbital, ground station as a
service, now in preview, 2020",
<https://tinyurl.com/ejfpre>.
Li, et al. Expires 28 April 2022 [Page 12]
Internet-Draft Problems and Requirements of Addressing October 2021
[BEIDOU-TEST]
"China tests inter-satellite links of BeiDou navigation
system", <https://tinyurl.com/3cufz6dt>.
[BGAN] "Broadband Global Area Network (BGAN)",
<https://en.wikipedia.org/wiki/
Broadband_Global_Area_Network>.
[ETSI-TS-101]
"ETSI. TS 101 376-1-3: GEO-Mobile Radio Interface
Specifications; Part 1: General specifications; Sub-part
3: General System Description",
<https://en.wikipedia.org/wiki/ETSI>.
[ETSI-TS-102]
"ETSI. TS 102 744-3-6: Satellite Earth Stations and
Systems (SES); Part 3: Control Plane and User Plane
Specifications; Sub-part 6: Adaptation Layer Operation",
<https://en.wikipedia.org/wiki/ETSI>.
[GEO-MOBILE-RADIO-INTERFACE]
"GEO-Mobile Radio Interface",
<https://en.wikipedia.org/wiki/GEO-
Mobile_Radio_Interface>.
[Giuliari20Internet]
Giuliari, G., Klenze, T., Legner, M., Basin, D., Perrig,
A., and A. Singla, "Internet backbones in space", ACM
SIGCOMM Computer Communication Review, 2020, 50(1): 25-37,
<https://dl.acm.org/doi/abs/10.1145/3390251.3390256>.
[GOOGLE-DATA-CENTER]
"ZDNet. SpaceX to put Starlink ground stations in Google
data centres, 2021", <https://tinyurl.com/pzy8vstx>.
[INTERNET-IN-SPACE]
Li, Y., Li, H., Liu, L., Liu, W., Liu, J., Wu, J., Wu, Q.,
Liu, J., and Z. Lai, ""Internet in Space" for Terrestrial
Users via Cyber-Physical Convergence", Proceedings of the
20th ACM Workshop on Hot Topics in Networks. 2021,
<https://conferences.sigcomm.org/hotnets/2021/>.
[ITU-Measure]
"ITU. Measuring digital development: Facts and figures
2020, 2020".
[KUIPER] "Amazon receives FCC approval for project Kuiper satellite
constellation.", <https://tinyurl.com/bs7syjnk>.
Li, et al. Expires 28 April 2022 [Page 13]
Internet-Draft Problems and Requirements of Addressing October 2021
[KUIPER-CGNAT]
"Amazon Kuiper", <https://eurospace.org/wp-
content/uploads/2020/11/information-note-amazon-
kuiper_18112020.pdf>.
[lai2021icnp]
Lai, Z., Li, H., Zhang, Q., Wu, Q., and J. Wu,
"Cooperatively constructing cost-effective content
distribution networks upon emerging low earth orbit
satellites and clouds", 2021 IEEE 29th International
Conference on Network Protocols (ICNP). IEEE, 2021.
[LOWLATENCY-ROUTING-SPACE]
Handley, M., "Delay is Not an Option: Low Latency Routing
in Space", Proceedings of the 17th ACM Workshop on Hot
Topics in Networks. 2018,
<https://dl.acm.org/doi/abs/10.1145/3286062.3286075>.
[NETWORK-IN-HEAVEN]
Klenze, T., Giuliari, G., Pappas, C., Perrig, A., and D.
Basin, "Networking in heaven as on earth", Proceedings of
the 17th ACM Workshop on Hot Topics in Networks. 2018:
22-28,
<https://dl.acm.org/doi/abs/10.1145/3286062.3286066>.
[NETWORK-TOPO-DESIGN]
Bhattacherjee, D. and A. Singla, "Network Topology Design
at 27,000 km/hour", Proceedings of the 15th International
Conference on Emerging Networking Experiments And
Technologies. 2019,
<https://dl.acm.org/doi/abs/10.1145/3359989.3365407>.
[ONEWEB] "OneWeb constellation", <https://www.oneweb.world/>.
[SATELLITE-COMMUNICATIONS]
Roddy, D., "Satellite communications. McGraw-Hill
Education",
<https://ui.adsabs.harvard.edu/abs/1977ph...book.....S/
abstract>.
[SOLUTION-NR-NTN]
"Solutions for NR to support non-terrestrial networks
(NTN)",
<https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=3525>.
Li, et al. Expires 28 April 2022 [Page 14]
Internet-Draft Problems and Requirements of Addressing October 2021
[SPACE-RACE]
Bhattacherjee, D., Aqeel, W., Bozkurt, I.N., Aguirre, A.,
Chandrasekaran, B., Godfrey, P.B., Laughlin, G., Maggs,
B., and A. Singla, "Gearing up for the 21st century space
race", Proceedings of the 17th ACM Workshop on Hot Topics
in Networks. 2018,
<https://dl.acm.org/doi/abs/10.1145/3286062.3286079>.
[SPACEX-CLAIM]
"Spacex claims to have redesigned its starlink satellites
to eliminate casualty risks",
<https://tinyurl.com/yryp2upy>.
[STARLINK] "SpaceX Starlink", <http://www.starlink.com/>.
[STARLINK-CGNAT]
"Petition of Starlink Services, LLC for Designation as an
Eligible Telecommunication Carrier",
<https://tinyurl.com/ury6rzw5>.
[STARLINK-GS-FOUND]
"Tesmanian. SpaceX Starlink Gateway Stations Found In The
United States and Abroad, 2021",
<https://tinyurl.com/4m5uah43>.
[STARLINK-GS-MAP]
"SpaceX Starlink Ground Station Map, 2021",
<https://tinyurl.com/pu59m7j3>.
[STUDY-NR-SUPPORT]
"Study on New Radio (NR) to support nonterrestrial
networks",
<https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=3234>.
[TEC-SPECI-GROUP-MEETING]
"Technical Specification Group Meeting #91E",
<https://www.3gpp.org/ftp/tsg_ran/TSG_RAN/TSGR_91e/Inbox/
RP-210915.zip>.
[TheVerge-STARLINK-SPEED]
"With latest Starlink launch, SpaceX touts 100 Mbps
download speeds and "space lasers" (though the system
still has a ways to go)", <https://tinyurl.com/hj8juyun>.
[TIMESLOT-DIVISION]
Li, J., Li, H., Liu, J., Lai, Z., Wu, Q., and X. Wang, "A
Timeslot Division Strategy for Availability in Integrated
Li, et al. Expires 28 April 2022 [Page 15]
Internet-Draft Problems and Requirements of Addressing October 2021
Satellite and Terrestrial Network", 2021 IEEE Wireless
Communications and Networking Conference (WCNC). IEEE,
2021: 1-7, <https://ieeexplore.ieee.org/document/9417256>.
[USE-GROUND-RELAY]
Handley, M., "Using ground relays for low-latency wide-
area routing in megaconstellations", Proceedings of the
18th ACM Workshop on Hot Topics in Networks. 2019:
125-132,
<https://dl.acm.org/doi/abs/10.1145/3365609.3365859>.
Authors' Addresses
Yuanjie Li
Tsinghua University
Beijing 100084
China
Email: yuanjiel@tsinghua.edu.cn
Hewu Li
Tsinghua University
Beijing 100084
China
Email: lihewu@cernet.edu.cn
Jiayi Liu
Tsinghua University
Beijing 100084
China
Email: liu-jy21@mails.tsinghua.edu.cn
Li, et al. Expires 28 April 2022 [Page 16]
