ISO/IEC 4005-1:2023

INTERNATIONAL ISO/IEC
STANDARD 4005-1
First edition
2023-03
Telecommunications and information
exchange between systems —
Unmanned aircraft area network
(UAAN) —
Part 1:
Communication model and
requirements
Télécommunications et échange d'information entre systèmes —
Réseau de zone de drones (Unmanned aircraft area network -
UAAN) —
Partie 1: Modèle de communication et exigences
Reference number
© ISO/IEC 2023
© ISO/IEC 2023
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© ISO/IEC 2023 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Communication model and requirements . 3
5.1 UA communication model . 3
5.2 UA communication requirements . 3
5.3 Communication structure and operation . 4
5.4 Purpose of the three types of communication and related services . 11
5.4.1 General . 11
5.4.2 Shared communication . 11
5.4.3 Control communication . 13
5.4.4 Video communication . 13
5.5 Interoperation of three types of communication . 13
5.6 Interworking with upper layers . 15
Annex A (informative) Information tone slot example .18
Bibliography .19
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© ISO/IEC 2023 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
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activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
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work.
The procedures used to develop this document and those intended for its further maintenance
are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria
needed for the different types of document should be noted. This document was drafted in
accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives or
www.iec.ch/members_experts/refdocs).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) or the IEC
list of patent declarations received (see https://patents.iec.ch).
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the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 6, Telecommunications and information exchange between systems.
A list of all parts in the ISO/IEC 4005 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.
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Introduction
Unmanned aircrafts (UAs) operating at low altitudes will provide a variety of commercial services in
the near future. UAs that provide these services are distributed in the airspace. In level II, many people
operate their own UAs without the assignment of communication channels from a central control
centre. In this case, wireless fidelity (Wi-Fi) is mainly used as a control channel and a video channel
in the unlicensed band. However, when using Wi-Fi, level II UAs can experience loss of control and
video links due to communication resource collision. In addition, UA-related units, such as vertiports
and obstacles, need a way to exchange information with UAs. This document introduces a wireless
distributed communication model to solve these problems.
The wireless distributed communication described by this document is intended to be used in licensed
frequency bands. By using licensed frequency bands, each unit is able to reliably allocate and use
radio resources at the desired time, various UA communications can coexist and cooperate, and the
probability of radio resource collision is very small.
Many services are required for UA operations. In order to support these services, communication
between units related with UAs, UA control communication, and video communication, are generally
needed.
The ISO/IEC 4005 series consists of the following four parts:
— ISO/IEC 4005-1 (this document): To support various services for UAs, it describes a wireless
distributed communication model and the requirements that this model shall satisfy.
— ISO/IEC 4005-2: It describes communication in which all units that can communicate with UAs can
broadcast or exchange information by sharing communication resources with each other.
— ISO/IEC 4005-3: It describes the control communication for the controller to control the UA.
— ISO/IEC 4005-4: It describes video communication for UAs to send video to a controller.
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© ISO/IEC 2023 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 4005-1:2023(E)
Telecommunications and information exchange between
systems — Unmanned aircraft area network (UAAN) —
Part 1:
Communication model and requirements
1 Scope
This document describes a communication model and requirements for unmanned aircraft area
network (UAAN), which is a wireless distributed communication network for units related with UA
services in level II.
It describes:
— the communication structure and operation;
— the purpose of the three types of communication and related services;
— the interoperation of the three types of communication;
— the interworking with upper layers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 4005-2, Telecommunications and information exchange between systems — Unmanned aircraft
area network (UAAN) — Part 2: Physical and data link protocols for shared communication
ISO/IEC 4005-3, Telecommunications and information exchange between systems — Unmanned aircraft
area network (UAAN) — Part 3: Physical and data link protocols for control communication
ISO/IEC 4005-4, Telecommunications and information exchange between systems — Unmanned aircraft
area network (UAAN) — Part 4: Physical and data link protocols for video communication
ISO 21384-4, Unmanned aircraft systems — Part 4: Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in ISO 21384-4 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
level II
airspace where maximum height is between 15 m (above ground level) and 120 m (above ground level)
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3.2
controller
device that controls an unmanned aircraft (UA) and which can also be equipped with a video receiver
(3.6) device
3.3
obstacle device
device that broadcasts related information, e.g. related obstacle location, radius, and which is mounted
to an obstacle that is placed on the ground or in the air
3.4
landing device
device that broadcasts related location information or information tone signals of a landing site and
which is mounted to a landing site and leads autonomous landing work
3.5
ground equipment
ground-based equipment that collects the information that unmanned aircrafts (UAs) broadcast and
uses the collected information to communicate the location and status of UAs to UA management
systems or UA operators
Note 1 to entry: Ground equipment can use shared communication to deliver the necessary messages to UAs.
3.6
video receiver
receiver that is mounted on a controller (3.2) and performs one-to-one communication with unmanned
aircrafts (UAs)
Note 1 to entry: For special services, separated multiple video receivers can receive video from a single UA.
3.7
unit
all objects that have transmitting or receiving functions, e.g. unmanned aircraft (UA), controller (3.2),
obstacle device (3.3), landing device (3.4), ground equipment (3.5)
3.8
data slot
slot constituting a data channel
3.9
tone slot
slot constituting a tone channel
3.10
slot clearing
transmission of a tone signal in subslot 0 in order to continue to occupy a slot already allocated from
the previous frame
3.11
slot map
bit string indicating whether slots are available
Note 1 to entry: In wireless distributed communication, the slot map of each unit (3.7) is generally different.
3.12
slot planning
specification by the upper layer on the type, usage, transmission power, and whether to apply a super
frame, for all slots of the channel in advance
© ISO/IEC 2023 – All rights reserved

3.13
tone subslot
subslot constituting a tone slot (3.9)
3.14
tone signal
signal transmitted in a tone subslot (3.13)
4 Abbreviated terms
CC Control Communication
RF Radio Frequency
SC Shared Communication
TDMA Time Division Multiple Access
TRX Transmission and Reception
UTC Coordinated Universal Time
VC Video Communication
5 Communication model and requirements
5.1 UA communication model
This document describes wireless distributed communication as a communication model. The
reason is that UAs and other related units on the surface or at low altitude are randomly distributed
in the airspace. These units need a way to communicate with each other. However, the problem
with distributed wireless communication is that there is no control station that manages resources
efficiently. Therefore, the communication model of this document is designed so that units can allocate
resources by themselves, occupy resources by themselves, detect resources collisions by themselves,
and return resources by themselves.
5.2 UA communication requirements
There are three commercial requirements for UA communication:
— safety;
— economy;
— convenience.
UA communication shall also meet this requirement in a wireless distributed communication
environment.
First, safety is the most important aspect in UA communications. Many UA services cannot be
provided without safety. Therefore, the UA communication link shall have the necessary functions and
performance. The necessary function is that all units that communicate with UAs can communicate with
each other when necessary. The main means of communication for UAs are control communications
and video communications. In addition, communication between UAs, communication between
UAs and ground equipment, communication between UAs and landing devices, and communication
between UAs and obstacles are also required. In particular, communication between UAs can
provide an optimal solution for small UAs to detect each other. Wireless distributed communication
is best suited to supporting these functions for UAs distributed in the airspace. In order for wireless
© ISO/IEC 2023 – All rights reserved

distributed communication to operate effectively, low probability of resource collision, real-time
resource collision detection, and rapid communication environment investigation are required. UA
communication is provided in an environment where multiple units are moving simultaneously. The
real-time movement of various units changes the communication environment in real time. Therefore,
the UA communication needs to quickly investigate such changes in the communication environment,
allocate necessary resources with a low probability of collision, and detect collisions in real time for the
occupied resources.
Second, this document supports many communication links simultaneously. Many communication
links are required to operate UAs. If each communication hardware supports communication between
UAs, communication between UAs and ground equipment, communication between UAs and landing
devices, and communication between UAs and obstacles, it is economically burdensome, so it should be
supported with as little hardware as possible.
The third requirement is convenience. Convenience can be divided into convenience from a
manufacturer's point of view and convenience from a user's point of view. Users want as many services
as possible with one communication device. Also, users generally want long battery life. Manufacturers
prefer the lowest hardware complexity. Low hardware complexity means smaller size and less weight.
Therefore, the requirements for UA communication are as follows:
a) All units that can communicate with UAs shall be able to communicate with UAs when necessary.
b) The wireless distributed communication with features of low resource collision probability, real-
time resource collision detection, and fast communication environment investigation shall be used.
c) Communication devices shall support as many services as possible with as little hardware as
possible.
d) Communication devices shall have as low a hardware complexity as possible.
5.3 Communication structure and operation
A new communication model is required to meet the UA communication requirements mentioned above.
It is a synchronous wireless distributed communication model. Among three types of communication,
video communications and control communications use a lot of communications resources. Therefore,
separate frequency channels are required. All communication except video communication and control
communication is supported as shared communication.
Therefore, the minimum required channels are shared channels, control channels, and video channels.
These channel configurations are shown in Figure 1.
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Key
1 shared link
2 control link
3 video link
4 controller
5 obstacle device
6 ground equipment
7 landing device
G level II
a
The altitude of level II.
b
Location broadcast and data exchange.
c
Broadcast.
Figure 1 — Three types of communications
As mentioned in 5.2, all three wireless distributed communications should feature low probability
of resource collision, real-time resource collision detection, and rapid communication environment
investigation.
To this end, three wireless distributed communications perform resource allocation, occupation,
collision detection and communication environment investigation using a tone channel. Data are
transmitted through a separate data channel with a centre frequency that is different from that of
the tone channel as shown in Figure 2. This multi-channel structure features low resource collision
probability, real-time resource collision detection, and fast communication environment investigation.
Figure 2 — Multichannel structure and the role of each channel
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In particular, the tone channel performs the following functions:
a) resource allocation;
b) resource occupation;
c) removal of hidden nodes;
d) real-time resource collision check;
e) transfer of information;
f) communication environment investigation.
The tone channel can investigate the communication environment in real time. In general, investigating
a multi-channel communication environment requires a lot of hardware and time. However, the tone
channel makes it possible to quickly investigate the communication environment of multiple channels
with one hardware.
As such, this communication model can perform as many functions as possible with as little hardware
as possible. Shared communication, control communication and video communication work in the same
way, which further allows the three types of communication to coexist.
A detailed description of the common communication model is as follows.
This communication model uses synchronous TDMA technology. Synchronization can be obtained from
signals received from the UTC system, or from signals transmitted by other units synchronized with
UTC.
The tone channel consists of 500 slots, and each slot consists of 33 subslots as shown in Figure 3. If a
unit allocates one tone slot, it is assumed to allocate the communication resource mapped with that tone
slot. For example, in shared communication, one tone slot is associated with one data slot assignment.
Key
1 1 frame = 1 second = 500 Ts
2 data channel
3 tone channel
4 tone slot
Figure 3 — Mapping concept of tone slot and data slot in shared communication
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Figure 4 — Mapping concept of tone slot and subchannel in control channel
In control communication and video communication, one tone slot is associated with one subchannel
allocation as shown in Figure 4.
Control communication resources and video communication resources exist in several frequency
channels. The unit does not need to examine all channels of all frequencies to determine which
subchannels are empty. If the unit receives only one tone channel, it can determine which subchannel of
which frequency is empty. This reduces the number of required RF hardware to a minimum. In wireless
distributed communication, in order to allocate several frequency resources by themselves, the state of
the corresponding frequency resources needs to be investigated in real time. If there is no tone channel,
the unit will need as many RF hardware as different frequencies to know the channel status of different
frequencies in real time.
This document describes a tone channel for shared communication and a tone channel for control
communication and video communication as shown in Figure 5, i.e. the control channel and the video
channel share one tone channel.
Key
SC shared communication
CC control communication
VC video communication
Figure 5 — Mapping of tone channels, shared channels, control channels, video channels
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Simply explained, communication resource allocation using the tone channel is performed in the tone
slot. The tone slot consists of 33 subslots. For resource allocation, the unit performs two competitions
in the related tone slot. The first competition is to randomly select the first subslot among subslots from
subslot 1 to subslot 32 with same probability. In this competition, the units that choose the earliest
number of slots win. For example, if three units A, C, and D each choose subslot 2, 5, and 31 respectively,
then unit A wins as shown in Figure 6 because unit A performs carrier sensing from subslot 0 to subslot
1 and transmits its tone signal from subslot 2 since the channel is empty. On the other hand, the C and D
units lose the competition because A's signal is sensed in subslot 2.
Key
Tx transmission
CS carrier sensing
A, C, D unit
a
Tone slot.
Figure 6 — First competition example
The second competition is performed by the units winning the first competition. The second competition
is to randomly select the second subsl
...