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PURPOSE AND SCOPE
Introduction and Purpose of Document
This document contains Minimum Aviation System Performance Standards (MASPS) for
coexistence of Wireless Avionics Intra-Communication (WAIC) systems operating within
the 4200-4400 MHz radio frequency band. The term WAIC refers to a broad class of
onboard wireless communication systems intended to provide data links between various
aircraft functions . This document provides designers of WAIC systems with guidance
on how to demonstrate coexistence of WAIC with other aircraft systems using the same
radio frequency spectrum.
The notion of WAIC was first introduced when the aviation industry requested the
International Telecommunication Union (ITU) to introduce a new frequency spectrum
allocation to enable operation of wireless data links on board aircraft related to safety and
regularity of flight. Resolution 424 of the 2015 World Radiocommunication Conference
(WRC-15)  defined WAIC systems as “radiocommunication between two or more
aircraft stations located on board a single aircraft, supporting the safe operation of the
aircraft”. The conference added to the Table of Frequency Allocations of the Radio
Regulations (RR) a new aeronautical mobile (R) service allocation in the frequency band
4200-4400 MHz, which is reserved exclusively for WAIC. Per Article 1.33 of the RR, the
aeronautical mobile (R) service is reserved for communications related to safety and
regularity of flight. Thus, non-safety-related uses such as in-flight entertainment or
passenger connectivity are expressly excluded from the scope of WAIC. The restriction of
WAIC to safety and regularity of flight related uses in absence of existing certification
guidance has created a need to develop such guidance for this new class of aircraft systems.
The need to address WAIC coexistence performance stems from the fact that the frequency
band 4200-4400 MHz also contains a preexisting allocation to the aeronautical radio
navigation service reserved exclusively for radio altimeters , . The new allocation for
WAIC was introduced under the condition that the use of WAIC cannot disrupt or degrade
operation of radio altimeters. Resolution 424 (WRC-15) expressly states that WAIC shall
not cause harmful interference to, nor claim protection from, radio altimeters . This in
effect grants priority to the aeronautical radio navigation allocation used by radio
altimeters. It poses a requirement on WAIC designers to assure protection of radio
altimeters, without creating any corresponding reciprocal requirement on radio altimeter
designers. The purpose of this MASPS is to provide WAIC designers with acceptable
means of demonstrating such protection.
Another purpose of this document is to assist the International Civil Aviation Organization
(ICAO) in the development of Standards and Recommended Practices (SARPs) for WAIC.
As part of World Radiocommunication Conference 2015 Resolution 424 mandated that
WAIC must comply with ICAO SARPs, which are currently in development. The crucial
aspects of these SARPs are that WAIC systems:
shall not interfere with radio altimeters on other aircraft,
shall not interfere with WAIC systems on other aircraft,
have to tolerate interference coming from radio altimeters on other aircraft.
Further detail on the above aspects can be found in the relevant sections of this document.
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