INCREASED WAVEFORM CAPACITY WITH PHASE OVERLAY
This Solution was formerly part of PJ.14-04-03-W1
Implementation of a wide range of surveillance technologies, including ADS-B, impacts data transmission. This solution addresses the future ADS-B communications link, in particular phase overlay for Mode S and ADS-B datalink.
This solution is using phase overlay techniques, which consists of overlaying phase-shift keying (8PSK) onto the pulse position modulation (PPM) messages to carry separated information, avoiding the need to modify the structure of the current extended squitter message or assigned spectrum. The extended number of bits in a phase overlay message allows additional data to be transmitted.
As such, phase overlay technology opens the possibility for future applications. This extension can be used for different applications, from transmitting new types of data (such as weather information), add cybersecurity layers (ADS-B technology is currently not protected and its service can be degraded by spoofing or eavesdropping attacks) or reduce the 1090MHz frequency congestion (diminishing the transmission rate sending the same amount of data in less messages). All these possibilities could be studied in future SESAR research projects. In addition, as the new modulation does not affect the original one, backwards compatibility is ensured. All these possibilities could be studied in future SESAR research projects.
Specifically, during Wave 2, PJ14-W2-84d has validated the improvement of the transmitted bit rate, increasing the data transmission from 112 to 448 bits (from 56 to 204 useful bits). The solution has also validated the waveform and performances required for the phase overlay transmitter and receiver currently standardised on ED-102B / DO-260C and ED-73F / DO-181F and has contributed to ongoing standardisation activities by RTCA SC-186 and SC-209, and EUROCAE WG-51.
BENEFITS
Depending on how the additional data bits are going to be used, the potential benefits could be:
- Cost efficiency,
- Increased security (hence safety),
- Or spectrum efficiency
Datapack