1. IALA proposals for PDNR ITU-R M.[VDES] – Annex 2
International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA)
IALA proposals for PDNR ITU-R M.[VDES] – Annex 2
Application Specific Message ASM
Stefan Bober
IALA e-NAV Committee
AIS/COMMS WG

2. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
VDES function: Application Specific Message
ASM exchange:
ship to ship independent from shore station,
ship to shore and shore to ship,
ship to satellite for long range transmission

3. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Use of the channels for Application Specific Message (ASM channels) of the VDES
Application Specific Messages are transferred on the AIS channels today
Application Specific Messages are defined in Rec. ITU-R M.1371.
ASM channels provides additional capacity for transmitting Application specific Messages
Relive the load of the AIS channels from Application Specific Messages

4. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Most of the existing application specific messages and new messages will be moved to the ASM channels
functions:
international ASM defined by IMO (SN Circ. 289)
regional ASM (e.g. IALA ASM collection)
allows for “real” communication including acknowledgement
high reliability of message reception
technical characteristic:
radio channel ASM 1, ASM2,
higher capacity than AIS channels
message structure as for msg 6,7,8,12,13,14,25,26
-> ASM with more capacity and better reliability of message delivery

5. IMO SN.1/Circ.289 „ Guidance on the use of AIS Application Specific Messages
Number of persons on board
VTS-generated/synthetic targets
Clearance time to enter port
Marine traffic signal
Berthing data
Weather observation report from ship
Area notice – broadcast / addressed
Extended ship static and voyage-related data
Dangerous cargo indication
Environmental
Route information – broadcast / addressed
Text description – broadcast / addressed
Meteorological and Hydrographic data
Tidal window

6. Channel Plan A provides channels for ASM
ITU-R M.[VDES] - Annex 2
Application Specific Message
Channel Plan A provides channels for ASM
Channels in the low frequency range of the VHF maritime mobile band
Channels in the high frequency range of the VHF maritime mobile band
Chanel No.
Frequency MHz
Function
Legend: 75
VHF Data Exchange
350 kHz
225 kHz
AIS LR 16 70
DSC
500 kHz 76
1024
1084
1025
1085
1026
1086
4.45 MHz
2024
2084
2025
2085
2026
2086
ASM 1
ASM 2
AIS 1
AIS 2
2027
2028
xxxx
MHz
MHz
Ship station analog voice transmission
Coast station analog voice transmission
VDE ship-shore transmit
AIS-VDE ship receiving bandwidth

7. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Technical characteristics of the Application Specific Message (ASM) channels for the VDES
Technical approach is similar to AIS:
Frame structure: 1 minute, 2250 slots, frame start UTC minute
Synchronisation: UTC direct or to AIS when UTC not available
Channel access: RATDMA, ITDMA, FATDMA, new SCTDMA
Message structure: existing ASM messages + new messages
Messages
Considering:
IMO requirement for AIS, protection of AIS
AIS for surveillance, tracking and VTS
VDES provides capacity for maritime data communications
Recognizing
VDES must ensure DSC, AIS and voice distress, safety and calling communication (Channel 16), are not impaired
Recommends
VDES should be designed in accordance with the Annexes
ASM considering Rec. ITU-R M.3171 and IMO SN Circ. 289
relevant technical requirements, recommendations and guidelines published by IMO, IEC and IALA

8. RF transceiver parameter
ITU-R M.[VDES] - Annex 2
Application Specific Message
RF transceiver parameter
Parameters
Requirements
ASM 1 (2027)
161,950 MHz, ± 500 Hz
ASM 2 (2028)
162,000 MHz, ± 500 Hz
Transmitter power
low: 1 W, high 12,5 W, ±1.5 dB
Slotted modulation mask
∆fc < ±10 kHz: 0 dBc
±10 kHz < ∆fc < ±25 kHz: line −25 dBc to -70 dBc
±25 kHz < ∆fc < ±62.5 kHz: –70 dBc
Spurious emissions
–36 dBm: 9 kHz GHz
–30 dBm: 1 GHz GHz
Receiver sensitivity
- 107 dBm
Adjacent channel selectivity
70 dB
Spurious response rejection
Intermodulation response rejection
74 dB

9. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
ASM has two radio transmission methods using different modulation schemes:
π/4 Quadrature Phase-Shift Keying (QPSK)
Gaussian-filtered minimum shift keying (GMSK)
π/4 QPSK is base modulation scheme
Primary channel access,
Bit rate: 19,2 kbit/s
GMSK provides inherited modulation scheme from AIS
Secondary channel access
Bit rate: 9,6 kbit/s

10. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method π/4 QPSK
π/4 Quadrature Phase-Shift Keying (QPSK)
transmission bit rate 19,2 kbit/s
Training sequence 27 bit
Signal information - selects modulation and coding 0000 – π/4 QPSK no coding;
0001 – π/4 QPSK 1/2 code rate;
0010 – π/4 QPSK 3/4 code rate; and
0011 – π/4 QPSK 5/6 code rate
Forward Error Correction, Interleaving, bit scrambling
Cyclic Redundancy Check: 32 bit ITU-T V.42

11. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Why only 19,2 bit/s?
Constellation diagram
π/4 QPSK
1 symbol = 2 bit
symbol length = 104 us
Interference from ASM transmissions to existing
satellite AIS receive

12. Radio transmission method π/4 QPSK
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method π/4 QPSK
Slot access: one slot = 26,66 ms
one frame = 2250 slots = 1 min, sync. to UTC
Packet format for π/4 QPSK (total 512 bits)
Long transmission packets up to 5 slots (5x512bits)

13. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method π/4 QPSK
Access to the data link – channel access schemes
ITDMA, RATDMA, FATDMA as defined in ITU-R M.1371
Cooperation on the data link:
ASM must give priority to AIS
Candidate slots selection:
4 candidate slots out of 150 slot selection interval
Following rules: (available slot = most distant station)
Free on AIS and ASM channels
Available on one AIS channel and free on all other channels
Available on both AIS channels and free on ASM channels
If not: don‘t transmit

14. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method π/4 QPSK
Broadcast messages
Addressed messages
User ID: 30 bits (e.g. MMSI)
Message structure: example for ITDMA message with ComState

15. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method π/4 QPSK
Messages as defined by IMO
Example from IMO

16. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method GMSK
Frequency modulated Gaussian filtered minimum shift keying (GMSK/FM)
transmission bit rate 9,6 kbit/s
BT-product tx = 0,4; rx = 0,5
Training sequence 24 bit
Encoding NRZI
No Forward Error Correction
No bit scrambling
Cyclic Redundancy Check: 16 bit according HDLC

17. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method GMSK
Access to the data link – channel access schemes
FATDMA as defined in ITU-R M.1371
Slot carrier sense TDMA / SCTDMA, (new)
Carrier sense timing

18. Radio transmission method GMSK
IALA proposal for ITU-R M.[VDES]
- Annex 2 -
Radio transmission method GMSK
Packet format for GMSK (total 256 bits) - autonomous mode
Long transmission packets up to 5 slots (5x256bits), FATDMA only
Carrier sense period
28 bits
Ramp up
8 bits
Training sequence
24 bits
Necessary for synchronization
Start flag
In accordance with HDLC (7Eh)
Data
140 bits
Default
CRC
16 bits
In accordance with HDLC
End flag
Buffer
Bit stuffing distance delays and jitter
Total
256 bits
Single slot packet bit structure for GMSK

19. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method GMSK
Broadcast messages
Addressed messages
User ID: 30 bits (e.g. MMSI)
Message structure of GMSK transmission using SCTDMA

20. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message
Radio transmission method π/4 QPSK
Satellite uplink may be provided by VDES equipment. It also may provide by dedicated equipment using slot carrier sense TDMA (SCTDMA) access scheme to consolidate AIS communications and terrestrial ASM communications.
The long-range ASM broadcast message should be transmitted only on ASM channels and not on the AIS channels (AIS channels: 75, 76, AIS 1, AIS 2 or regional channels).

21. Satellite uplink message for ITDMA, RATDMA, FATDMA
ITU-R M.[VDES] - Annex 2
Application Specific Message
Satellite uplink message for ITDMA, RATDMA, FATDMA
Slot composition
Bits
Notes
Ramp up 16
Standard
Pre training sequence
100
0011 (repeat for 100 bits)
Training sequence 27
Signal information 7
Decoded from Hamming (7,4)
0000 – not coding
0001 – 1/2 code rate
0010 – 3/4 code rate
0011 – 5/6 code rate
Data length 10
Default : “ ” (412) encoded data and crc;
Data field
166
Without encoding: 166 bits ; With encoding: varies according to coding rate defined in the Signal Information field
CRC 32
Without encoding: 32 bits; With encoding:  varies according to coding rate defined in the Signal Information field;
Only the data length and data field are included in the CRC
Buffer
154
Synch jitter (mobile station) = 6 bits Synch jitter (mobile/satellite) = 2 bits Propagation time delay difference = 144 bits; Spare = 2 bits
Total
512
Maximum 512 bits for 19.2 kbits/s π/4 QPSK

22. Satellite uplink message for SCTDMA
ITU-R M.[VDES] - Annex 2
Application Specific Message
Satellite uplink message for SCTDMA
Slot composition
Bits
Notes
Carrier sense period 56
Not transmitting (2 917 µs, equivalent to 56 bits)
Ramp up 16
Standard
Pre training sequence 44
0011 (repeat for 44 bits)
Training sequence 27
Signal information 7
Decoded from Hamming (7,4)
0000 – not coding
0001 – 1/2 coding
0010 – 3/4 coding
0011 – 5/6 coding
Data length 10
Default : “ ” (412) encoded data and crc;
Data field
166
Without encoding: 166 bits; With encoding: varies according to coding rate defined in the Signal Information field
CRC 32
Without encoding: 32 bits; With encoding:  varies according to coding rate defined in the Signal Information field;
Only the data length and data field are included in the CRC
Long-range ASM receiving system buffer
154
Synch jitter (mobile station) = 6 bits Synch jitter (mobile/satellite) = 2 bits Propagation time delay difference = 144 bits; Spare = 2 bits
Total
512
Maximum 512 bits for 19.2 kbits/s π/4 QPSK

23. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message

24. Application Specific Message
ITU-R M.[VDES] - Annex 2
Application Specific Message