AERONAUTICAL COMMUNICATIONS PANEL (ACP) 21 MEETING OF THE WORKING GROUP F

safflowerpepperoniΚινητά – Ασύρματες Τεχνολογίες

24 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

88 εμφανίσεις

(
7

pages)

safflowerpepperoni_e27b75d3
-
89b2
-
4e03
-
827f
-
fefb7a50b5b6.doc



AERONAUTICAL COMMUNICATIONS PANEL (ACP)


21
st

MEETING OF THE WORKING GROUP F


Bangkok, Thailand, 8


18 December 2009



Agenda Item
xx
:

Xxx



WIRELESS AVIONICS INTRA
-
COMMUNICATIONS (WAIC)


POTENTIAL FREQUENCY BANDS


(Presented by
Joe Cramer US AVSI, Uwe Schwark Germany AVSI
)



SUMMARY

The international aviation industry is studying characteristics of Wireless
Avionics I
ntra
-
Communications systems intended for wireless
communications applications between points on a single aircraft impacting the
safety or regularity of flight. This paper presents initial thoughts on potential
frequency bands for future WAIC systems.

ACTI
ON

To provide guidance and support for the identification of suitable spectrum for
future WAIC systems and to consider ICAO support for a potential proposal
for a new agenda item at WRC
-
12 on the identification of spectrum for WAIC.


1.

INTRODUCTION

Wireles
s Avionics Intra
-
Communication (WAIC) systems are considered as a replacement for existing
aircraft systems employing wires for communications purposes and as an enabler for new on
-
board
wireless communications applications. Deploying WAIC systems impactin
g safety or regularity of flight
requires operating in spectrum recognized by the Convention on International Civil Aviation. The ITU
-
R
Radiocommunication Assembly approved the study question 249/5 to determine the technical
characteristics and operational

requirements of WAIC systems
1
. Resolution of this question is currently



1

ITU Radiocommunication Assembly, QUESTION ITU
-
R 249/5 “ Technical characteristics and operational
requirements of wireless avionics intra
-
communications (WAIC)”, 2009



International Civil Aviation Organization


WORKING PAPER

ACP
-
WGF
21
/
WP
-
06

09/11/27



ACP
-
WGF
21
/
WP
-
xx


-

2
-

being conducted by ITU
-
R WP5B, which continues to study the issue.
2

The United States and CEPT
submitted contributions to the November 2009 ITU
-
R WP5B meeting providing technical char
acteristics,
predicted accumulated data rates, and power level requirements for potential WAIC systems. Brazil
submitted a document providing a glossary of terms. These documents were incorporated into the current
Preliminary Draft New Report (PDNR) on thi
s topic. The revised PDNR is submitted in Annex A. The
Aerospace Vehicle Systems Institute (AVSI) is also working on the next update of this PDNR and is
preparing a preliminary proposal for specific frequency bands that may be considered by the ITU and
ICA
O for accommodating WAIC applications. AVSI has informed ACP WG
-
F and WG
-
W about the
WAIC effort through a series of informational documents and presentations.
3

Based on preliminary analyses, it is most likely that radio frequency spectrum is required in a
eronautical
spectrum below 10

GHz for low data
-
rate WAIC systems and spectrum above approximately 20

GHz for
the high data
-
rate applications. This information document addresses potential frequency bands below
10

GHz for WAIC systems with per
-
node data rat
es lower than 10 kbps and associated low power
transmission. The AVSI member companies believe that a potential band can be found among one of the
already existing aeronautical allocations. An advantage of such a solution is that coexistence studies may
be

essentially restricted to the incumbent and future aeronautical users of such bands. In many cases, the
aeronautical applications utilizing the current aeronautical radio frequency spectrum are under regulatory
and operational control of aviation regulato
rs, aircraft manufacturers and operators who are also
ultimately responsible for coexistence between WAIC and incumbent systems.

This contribution presents three potential frequency bands for discussion. AVSI seeks feedback and
guidance from ACP WG
-
F regar
ding the feasibility of utilizing WAIC applications in one of these radio
frequency bands. These three bands are being initially considered based upon their potential technical
suitability for WAIC systems as well as potential compatibility with incumbent
systems. AVSI realizes
that much more detailed analyses will be required to substantiate a future spectrum proposal.

In addition to the ongoing compatibility studies and selection process the aerospace industry is
considering establishing a new agenda item

(under WRC
-
12 Agenda Item 8.2) identifying spectrum for
WAIC systems. AVSI is asking ICAO to support this potential Agenda Item, e.g. by adding WAIC to the
draft ICAO position paper dealing with WRC
-
12 matters.

To date three frequency bands have been init
ially reviewed as potential candidate bands for
accommodating low data
-
rate WAIC systems. This cursory analysis is not exhaustive. Our initial thoughts
are described below:

2.

DISCUSSION

2.1

Potential WAIC candidate band 4200


4400 MHz

The 4 200


4 400 MHz band

is allocated to the aeronautical radionavigation service and is, according to
footnote 5.438 of the ITU
-
R Radio Regulations exclusively reserved for radio altimeters installed on



2

ITU
-
R Radiocommunication Stud
y Groups Annex 15 to Document 5B/296
-
E, “Technical Characteristics and
Operational Objectives for Installed Wireless Avionics Intra
-
Communications (WAIC)”, 2 June 2009.
http://www.itu.int/md/R07
-
WP5B
-
C
-
0296/en

3

ACP
-
WGF 17/WP19, “Dedicated Frequency Alloca
tion for Aircraft On
-
Board Wireless Systems”, Nairobi, 19
-
25
September 2007. ACP
-
WGF 18/WP05, “The Technical Characteristics and Performance Objectives for Installed
Wireless Avionics Intra
-
Communications (WAIC) Systems”, Montreal, 15
-
19 May 2008. ACP/WG
F 20/WP07,
“Draft Revisions to Working Document on Technical Characteristics and Operational Objectives for Installed
Wireless Avionics Intra
-
Communications (WAIC)”, Montreal, 24 March


3 April 2009

ACP
-
WGF
21
/
WP
-
xx


-

3
-

board aircraft and associated transponders on the ground. This band is predo
minantly used for low range
radio altimeter applications on board civil and military aircraft depending on the implementation of the
Radio Regulations on individual national level. For civil aircraft the predominant radar principle used is
FMCW (Frequency
Modulated Continuous Wave). Military aircraft apply both FMCW and pulsed type
radars.

Typical characteristics and the usage profile of low range radio altimeters on board civil aircraft suggest
that coexistence with future WAIC applications could be possib
le due to the following:

a)

Low range radio altimeters apply radio magnetic waves emitted and received predominantly over
transmit/receive paths, which are orthogonal to the earth's surface using directive antennas
usually installed underneath the aircraft fu
selage. This fact suggests that coexistence of both
applications in the same band is viable by adequate spatial separation and a thorough design of
the antennas applied by both applications. A joint optimization of the antennas on the aircraft is
reasonabl
e since both systems including their installation are under the full control and
responsibility of the aircraft manufacturer. The directivity of radio altimeter signals and low
power transmissions of WAIC systems may also ensure that WAIC systems do not ca
use
interference to the radio altimeter of another aircraft.

b)

In radar systems, the signal
-
to
-
interference ratio at the radar receiver input increases as the
distance to the target decreases, assuming the interference power level remains constant. With
resp
ect to the low range radio altimeter case, this means the reception quality and hence the
precision of the altitude
-
over
-
ground measurement, increases with decreasing altitude during an
approach to an airport. This factor makes the low range radio altimete
r inherently robust against
in
-
band and adjacent band interference.

c)

The commonly used principle in low range radar altimeter implementations for commercial
aircraft is the FMCW principle. FWCW
-
based radars apply a linear up
-
chirp followed by a down
-
chirp s
ignal with a given constant frequency variation rate. The difference in frequency between
the instantaneous transmit frequency and the frequency of the receive signal reflected by the
target object (the ground) is proportional to twice the distance between

the radar antenna and the
target object. Usually the frequency sweep of the chirp signal occupies between 100 and
150

MHz of bandwidth in state
-
of
-
the
-
art implementations. But, in a given time interval, the
bandwidth instantaneously occupied, is only a fe
w kHz. This fact may be exploited when
designing a medium access protocol for WAIC systems actively avoiding interference with radio
altimeter transmissions.

2.2

Potential WAIC candidate band 5 030


5 091 MHz

The 5 030


5 091 MHz band is currently allocated
to two aeronautical services:

Aeronautical Radio Navigation Service (ARNS)

This allocation supports implementation of the Microwave Landing Systems (MLS) and takes precedence
in this band (per footnote 5.444 of the ITU
-
R Radio Regulations). MLS is a precis
ion approach and
landing guidance system that provides position information and various ground
-
to
-
air data from ground
transmitters to airborne receivers at altitudes up to 20,000 feet and ranges out to 22.5 nautical miles. A
regional frequency assignment
and implementation plan for MLS has been prepared for Europe. In March
2009 an MLS system was commissioned at Heathrow airport that supports Cat III operations.
Additionally, mobile MLS stations are utilized to support precision approach capability at mili
tary
airfields that have limited or no installed navigation aids.

ACP
-
WGF
21
/
WP
-
xx


-

4
-

Typical broad characteristics and usage profiles of MLS systems suggest that coexistence with future
WAIC applications could be possible due to the following:

a)

For WAIC systems collocated on
the same aircraft with an MLS receiver, the WAIC system
could be designed to have knowledge of the selected MLS channel, and avoid utilizing that
channel.

b)

The low power level of WAIC systems combined with aircraft attenuation and free
-
space loss due
to min
imum aircraft separation requirements may ensure that WAIC systems do not interfere with
MLS receivers on adjacent aircraft (operating in the same airspace or at the same airport).

c)

WAIC systems could also deploy algorithms, which would detect MLS transmitt
ers and select
not
-
occupied channels to ensure reliable WAIC operation. This would also serve to prevent
WAIC interference to MLS receivers on adjacent aircraft.

The frequency band study to support control links for UAS, Preliminary Draft New Report under
WRC
-
12 Agenda Item 1.3, provides a good description of and protection requirements for MLS systems. This
document will be utilized for future potential compatibility studies.

Aeronautical Mobile
-
Satellite (Route) Service (AMS(R)S)

A primary allocation for
AMS(R)S is also provided per footnote 5.367 of the ITU
-
R Radio Regulations.
Footnote

5.367

states that AMS(R)S has a primary allocation from 5 000 to 5 150 MHz. Since footnote
No.
5.444
states that the requirements of MLS take precedence over other uses of

the 5 030
-
5 091 MHz
frequency range, any 5 030
-
5 091 MHz AMS(R)S or WAIC system would have to give precedence to
MLS.

A proposal to develop a satellite
-
based UAS control link within the 5 000
-
5 150 MHz band was recently
introduced in the European Organiza
tion for Civil Aviation Equipment (EUROCAE) and other forums.
4

2.3

Potential WAIC candidate band 9 300


9 500 MHz
5

The 9 300


9 500 MHz band is allocated to a variety of primary status services including:


-

Airborne weather radar (AWR) systems (according to f
ootnote 5.475 of the ITU
-
R Radio
Regulations),

-

Radionavigation, including ground based meteorological, maritime coast and shipborne radars,

-

Earth
-
Exploration Satellite Service (EESS) and

-

Space Research Service.


Initial compatibility assessments between po
tential WAIC applications and incumbent services must
address the following:


a)

Radars operated in the band 9 300


9 500 MHz are likely to remain in service for many
years into the future. Sharing between AWR and meteorological radars on one hand and
mariti
me radars on the other hand is possible and practical because of the different
geographical usage, and good coordination between these services. Sharing with other
services including WAIC needs careful study.




4

A. Klaeyle,
The 5 GHz “Safety Satcom” Infrastructure,

UAS_305.1, EUROCAE WG
-
73, 31

December

2008.

5

The 9 000


9 200 MHz band may also be a viable candidate but has not yet been analyzed in detail.

ACP
-
WGF
21
/
WP
-
xx


-

5
-


b)

Ground
-
based radars may interfere with WAIC sy
stems. This may even be true for the
case of WAIC applications located inside the aircraft fuselage. Dynamic channel
selection methods, similar to those used by RLANs in the 5

GHz radar bands, may
support co
-
existence.


c)

Maritime and shipborne radars may in
terfere with WAIC systems under certain
circumstances, e.g. when aerodromes and maritime facilities are located in close vicinity.
As in the case of ground
-
based radars, techniques actively avoiding interference may
support coexistence between these radars

and WAIC systems.



d)

AWR signals may interfere with WAIC transmissions and vice versa. In particular this is
true for the case of landing gear sensors. Appropriate mitigation strategies will have to be
developed.


e)

Co
-
existence between the EESS and WAIC ap
plications


f)

Co
-
existence between the Space Research Service and WAIC applications


2.4

Future band candidates for high data
-
rate systems

This document addresses only candidate frequency bands for low data
-
rate WAIC systems. A parallel
effort is under way at AV
SI to identify suitable candidate bands for high data
-
rate WAIC systems.
Because of the wider bandwidth required, this will most likely yield bands above 20

GHz that do not
currently include aeronautical safety allocations. A future contribution to ITU
-
R W
P5B will provide a
spectrum proposal for low data
-
rate systems, based on feedback to this document, and a spectrum
proposal for high data
-
rate systems, which is not addressed here.

3.

CONCLUSION

The ability to use WAIC applications globally is extremely impor
tant to the commercial aviation industry
and presents a significant challenge given the international nature of air travel. The aviation industry is
striving to utilize wireless systems for both system upgrades on current aircraft, and in new aircraft desi
gn
that will be at least as safe as current wired systems, while reducing costs. The support of ICAO in
enabling WAIC applications to benefit from the certification efficiencies provided to avionics systems
and to benefit from the protections provided to a
viation spectrum is essential for implementing such
applications. WAIC systems will require to be defined as a safety service on a global basis. First analysis
of suitable frequency bands indicates that sufficient spectrum necessary for accommodating the i
dentified
WAIC applications may not be obtained without modification of the existing Radio Regulations. The
aviation industry will depend upon ICAO and its member administrations in order to obtain the necessary
spectrum. Early indication of support for a
potential Agenda Item from ICAO in this matter will help in
acquiring support from Administrations.

4.

ACTION BY THE MEETIN
G

The ACP WGF is invited to:

a)

provide guidance and support for the identification of suitable spectrum for future WAIC
ACP
-
WGF
21
/
WP
-
xx


-

6
-

systems.

b)

consider
ICAO support for a potential proposal for a new agenda item at WRC
-
12 on the
identification of spectrum for WAIC.

ACP
-
WGF
21
/
WP
-
xx


-

7
-

ANNEX A

ITU
-
R WP5B, “PRELIMINARY DRAFT NEW REPORT ITU
-
R M.[WAIC]
-

TECHNICAL
CHARACTERISTICS AND OPERATIONAL OBJECTIVES FOR INSTALLED WIRELE
SS
AVIONICS INTRA
-
COMMUNICATIONS (WAIC)”, December 2009