HFLINK Comments to ARRL on Development of New HF Digital Communications Protocols
HFLINK	An international resource for radio operators for ALE Automatic Link Establishment, High Speed and Robust HF Digital Communications, and Ionospheric Propagation.	hflink.com

To: ARRL

Attn: Paul Rinaldo, Chief Technology Officer

Re: HFLINK Comments to ARRL on Development of New Digital Communications Protocols

Date: 14 May 2007

Background

On 22 Feb 2007, the ARRL announced ^{See Note 1} that it seeks comments from amateurs concerning development of an open-source, non-proprietary, data communications protocol suitable for use by radio amateurs over HF fading paths.

HFLINK, an international resource for radio operators, for High Speed and Robust HF Digital Communications, ALE Automatic Link Establishment, and Ionospheric Propagation, with a membership of 1200 radio operators, including more than 900 licensed operators in the amateur radio service of USA, discussed ARRL’s announcement at length in the HFLINK Forum and via private correspondence.

HFLINK now respectfully submits the following comments in response to ARRL’s announcement:

Comments

We don't believe it is necessary to re-invent the HF data wheel for digital communications protocol, or desirable to invent a completely new ham-only standard digital data protocol built from the ground up, especially when we can leverage a suite of existing USA and global HF standards to provide an excellent working protocol for the ham community. Any modulation or coding system proposed should be intellectual property rights free, either by being in the public domain, or by having any patent holders issue a free non-discriminatory license for non-commercial use. Another consideration is that the protocols should bear in mind that such common standards last for decades, and thus should not be tied or limited to today's hardware capability or a unique platform, bandwidth, or present regulatory symbol rate limit. We believe that existing FED, MIL, and STANAG HF data communications standards provide a wonderful basis for expansion and development in amateur radio service. We can leverage and be the beneficiary to the vast research and development that has been expended.

In this document, we offer the following recommendations and research to support our comments:

PSK and MFSK for Data Communications

Recent advanced research and development in the HF industry arena for commercial and governmental applications has shown that PSK and MFSK with single tone physical layers tend to excel in the area of ARQ data HF communications. While OFDM based physical layers with FEC tend to excel in the area of HF Digital Voice applications. With regard to PSK and MFSK, the power levels of the transmitted signal are at nearly constant high amplitude, and the nature of the signal at high speeds does not require the kind of careful transmitter adjustments, high specifications, and linearities that OFDM with amplitude modulation needs for maximum throughput and signal integrity. Therefore, since this comment document is in response to ARRL’s desire for responses concerning data communications protocols, we hereunder recommend the adoption of PSK and MFSK based physical layers for data communication, especially for ARQ data. Since amateur radio equipment of all types will be used by operators, it is important that the physical layer of the data formats be robust and clean with little need for special ALC constraints or stringent IM3 specifications. Slower TR switching is also a requirement if existing ham radio equipment and PC computers are to be enabled by the adopted protocol standards when using ARQ. Successful systems meeting these constraints have been demonstrated, and indeed are already in use by ham operators in USA and internationally.

Digital Voice OFDM and HF Digital Voice Repeater

As an auxiliary comment, we recommend more research and development of OFDM physical layers for digital voice, specifically in the area of a scalable physical layer protocol, able to be time-multiplexed and interleaved, using bursts of compressed voice data, to enable a single-channel digital voice repeater on HF in a 5kHz or 6kHz bandwidth. The application of such a digital voice repeater, with less than 2 seconds realtime delay, on HF in emergency and relief applications is tremendous. The potential for day-to-day popularity of such a system would ensure its ready use, and also extend the amateur radio community in a forefront position for HF technology.

Existing Standards, Especially STANAG 5066, Ready for Further Amateur Development

MIL-STD 188-141, MIL-STD 188-110, FS-1045, FS-1052, and STANAG 5066 standards are ready for hams to use for the purpose of HF digital communications. Existing software and hardware solutions presently exist, and are in use by hams, for most of these protocols. We especially see the 5066 protocol as a wonderful area of data protocol where ARRL could benefit the entire amateur radio community by encouraging and fostering development of a PC-based program. 5066 is a modem-neutral protocol layer that provides a non-proprietary system for HF data communications interface with internet protocols. It is presently in use by governmental and non-governmental entities on HF, as a workhorse for HF digital data communications including HF email and other HFIP applications.

Recommending Adoption of a Protocol Suite

In the following comments, HFLINK proposes the adoption of several existing data protocols for different purposes of data communications, along with some new protocol development, forming a suite of protocols as a standard. ARRL is in a good position to develop and adopt such a standard, and for that standard to be used throughout the international ham community. HFLINK especially sees the advantages of such development for application by amateur radio service in Emergency and Disaster Relief. In order for the ham community to establish readiness in this area, it is necessary for hams who use the protocol and standards to have good familiarity and daily operations communicating via the standards. It is only with common use of these communications that emergency capability will be ensured. Thus, the standard should provide day-to-day utility that serves the needs of hams for common texting, calling, email, SMS, and data messaging. The various levels of protocol recommendations are described below, and detailed in Tables 1, 2, 3, 4, 5, 6, of this document.

Foundation of Protocol Suite: Physical Access

We propose that new HF digital standard protocols be based upon a foundation of Automatic Link Establishment (commonly known as 141 ALE) for access at the primary connection level between station-to-station and station-to-server, and that a multi-tiered approach to protocol standard levels and data transfer methods be used to accommodate existing equipment and anticipate future needs and development.

The use of 141 ALE at the foundational Access Protocol Level provides an existing system with a proven track record, that bridges all operating systems and platforms. It is currently available embedded in HF transceivers. 141 ALE is presently in use in the amateur radio community, and successful implementation of ham radio friendly ALE standards of operation, forged and developed by HFLINK over the past 6 years, has enabled 141 ALE to exist without interference problems. This includes the international coordination of HF channel frequencies, the use of polite and busy-channel recognition procedures, and the use of ALE protocol settings that are optimized for ham radio. ALE was originally envisioned as a way for unskilled operators to establish communications on HF. The amateur radio community has adopted and molded ALE into something more than the originators had envisioned. In the hands of a skilled amateur radio operator, ALE is a wonderful tool for communicating. It enables the unparalleled excellence in use and discovery of HF ionospheric band openings, the ease of selective calling of stations, the calling-up of hot-standby nets, instant CQ answers, bulletin dissemination, along with brief text messaging as an added bonus. It also includes the use of busy-channel detection, and fluid SSB voice in various embodiments.

Proposed ALE Station Installation at W1AW

We propose that ARRL set an encouraging example for the ham community by installing a 141 ALE HF station at W1AW and immediately begin transmitting QST announcement bulletins using ALLCALL address ALE on the internationally recognized amateur radio ALE data and voice channels. The proposed format for QST announcement data bulletins using 141 ALE is initial AMD header, followed by 141 ALE -based 8FSK using non-ARQ DBM. Such a 141 ALE station at W1AW is a perfect flagship platform for implementation of the communication protocol standards developed by ARRL through this comment process.

141 ALE is completely OS neutral. It is a US federal standard, published and free for hams to use worldwide. Over the past 5 years, 141 ALE has become the defacto universal global standard for HF connectivity for voice and/or data communications. Until recently, only about a thousand hams had 141 ALE capability, using commercial ALE transceivers and ALE controllers or PCALE software with amateur transceivers. In 2006, two new embedded HF ALE transceivers became available on the market in the amateur radio price range (under $US1500), the Icom IC-F7000, and the Vertex VX-1700 (Yaesu). In 2007, MULTIPSK software added 141 ALE with ARQ data. HFLINK is presently corresponding with other ham software authors who are working to add 141 ALE in their products. The addition of 141 ALE into the popular MULTIPSK software has greatly expanded 141 ALE among thousands of hams worldwide, practically overnight.

141 ALE is currently implemented in many different operating systems such as:
Hardware - no external computer required) embedded in transceivers such as Icom IC-F7000, Vertex VX-1700, Micom, Harris, Rockwell, R&S, Codan, etc. etc.
Software - PCALE, MULTIPSK, or MARS-ALE running on PC computers interfaced to ham or commercial transceivers.
External ALE hardware controllers: such as Harris and Rockwell, interfaced to HF commercial or mil transceivers.

Some advantages of 141 ALE for amateur radio use:
1) Message send/receive by portable transceivers, visible on panel display, without computer attached
2) Audible alarm call-up for individual operators or nets
3) Enables Hot Standby Nets 24/7/365
4) Global Standard and Interoperability with other agencies and services
5) Bulletins/Messages QSTs, with verification for unattended/attended
6) Different platforms available (including free and low cost software)
7) Good blend of Fast and Robust
8) Standardized HF freqs for ham radio (already internationally and regionally coordinated)
9) Common system for both data and voice
10) Geo-Position Reporting and status reporting
11) HF to SMS phone messaging or short text internet email possible with HF servers
12) ARQ and high speed modem handoffs for files and/or texting
13) Proven track record

ACCESS INITIAL PROTOCOL LEVEL ^{See TABLE 1}

We recommend adoption of protocol MIL STD 188-141, FED-1045 for calling, Automatic Link Establishment, alerting, connecting, CQ, QSY, interoperability, and net management.

DATA BASIC PROTOCOL LEVEL ^{See TABLE 2}

We recommend adoption of protocol MIL STD 188-141, FED-1045 for short text messaging, bulletin transmissions, QSTs, SMS-messaging, short email text messaging, and interoperable messaging.

DATA MEDIUM PROTOCOL LEVEL ^{See TABLE 3}

We recommend adoption of 8FSK ARQ, derived from MIL STD 188-141, FED-1045, for medium speed text-based and binary-based messaging, email, keyboarding chat, etc.

DATA ADVANCED PROTOCOL LEVEL 1 ^{See TABLE 4}

We recommend adoption of PSK - ARQ, derived from MIL STD 188-110, using a modified physical layer 6PSK at 2400 baud ARQ and non-ARQ, and the 110 standard 8PSK up to 4800 baud ARQ and non-ARQ, for high speed email, chat, chatroom, mobile web browser, internet functions, etc. These formats are presently available in the PCALE, MARS-ALE, and RFSM-2400 software modems, and usable with amateur equipment. They provide impressive throughput and robustness.

DATA ADVANCED PROTOCOL LEVEL 2 ^{See TABLE 5}

We recommend the new development and adoption of existing higher speed PSK with FEC and ARQ for high speed email, digital voice, mobile web browser, internet functions, etc. ARQ functions should be compatible with slow TR switching.

DATA HF-IP PROTOCOL LEVEL ^{See TABLE 6}

We recommend the adoption of Stanag 5066 (Open 5066) and FS-1052 in the interim, for higher protocol layers, for interface with the internet, management of data traffic, and interface between networks. We recommend that ARRL fosters and encourages development of 5066, and commences a project to develop a 5066 software program for PC, and use it as an open standard protocol for the Amateur Radio Service for HF internet.

Further Development

If a development path for new physical and protocol layers is embarked upon, it is suggested that it includes the following:

1)The ability to rapidly detect the presence of the waveform on channel even if off tune for CSMA (busy-channel detection) purposes.
2) Scaleable to different channel bandwidths 
3) Support ARQ and Broadcast.
4) Bitpipe including a sync on data capability 
5) Packet mode
6) Open source
7) Channel Adaptive 
8) Tolerant of transmitter misalignment
9) Ability to track Doppler shift and transmitter drift
10) Ability to tolerate Doppler spreading
11) Can be used on VHF as well as HF
12) Support for digital voice
 

CONCLUSION

HFLINK respectfully asks ARRL to carefully consider the comments and recommendations provided in this document. We believe ARRL is in a unique position to encourage and foster development of standards in the amateur radio service of USA and the ham community worldwide.

Submitted on behalf of the members of HFLINK Forum and HFLINK,

//s//

Bonnie Crystal, KQ6XA

Founder, HFLINK

Attachments:

1. TABLES

2. NOTES

ATTACHED NOTES AND TABLES

TABLE 1 - INITIAL ACCESS LEVEL

STATUS	Existing Protocol
SIGNAL TYPE	8FSK tones at 750Hz to 2500Hz
NECESSARY BANDWIDTH	1.75 kHz
OCCUPIED BANDWIDTH	2.1 kHz
SYMBOL RATE	125 Symbols/sec
BIT RATE	375 bits/sec
SNR	-3dB
BASIS	Non-Proprietary MIL-STD 188-141 / FS-1045
METHOD	Amateur Radio Subset of 2G ALE
ACCESS SEEKING	Multi-channel scanning, manual channel selection, or VFO dial selection
PILOT CHANNELS	1 channel for each ham band currently (expandable with auto-QSY)
ACCESS METHOD	Time-shared channels, scanned by base stations
INITIAL ACCESS TIME	30 seconds per band maximum
FUNCTIONS:	-a) Direct Call with alerting peer-to-peer or peer-to-server -b) Net callup with alerting -c) Bulletin with alerting (one-to-many) -d) Initialize contact and negotiate data level -e) Activity detection and busy channel detection -f) Negotiate remote QSY and auto-QSY -g) Instant stand-alone server or node -h) 24/7 "Hot Standby" Nets -i) Scan for connections to any station from any station -j) Emergency Alerting Signaling to/from stations -k) Emergency response signaling to/from stations -l) Access connection on an optimum channel -m) Ad-hoc networks or QSOs -n) Standard channels -o) Ending or clearing the connection -p) Manage network organization
ADVANTAGES:	-a) World standard for HF connectivity -b) Proven effective and efficient -c) Available at low cost, running on PCs -d) Available embedded in HF transceivers -e) No research and development program needed -f) Dependable -g) No prior network registration needed
DISADVANTAGES:	-a) Format presently unfamiliar to most hams -b) Network management needs planning

TABLE 2 - DATA BASIC LEVEL

STATUS	EXISTING
SIGNAL TYPE	8FSK tones at 750Hz to 2500Hz
NECESSARY BANDWIDTH	1.75 kHz
OCCUPIED BANDWIDTH	2.1 kHz
SYMBOL RATE	125 Symbols/sec
BIT RATE	375 bits/sec
SNR	-3dB
BASIS	Non-Proprietary MIL-STD 188-141 / FS-1045
FORMAT	AMD Automatic Message Display, aka Orderwire
FUNCTIONS	-a) Texting and Simplex Chat between operators -b) Interoperable texting to/from other Emergency Services -c) SMS to/from cell phones -d) Internet IM -e) Emergency Alerting -f) Stored Message when operator unavailable -g) Station or Operator Status Reports -h) Short Email -i) Geo Position Reporting (see ALE-GPR) -k) Commands for QSY, mode change, or Control of equipment
ADVANTAGES:	-a) Provides simple robust text messaging between stations -b) Provides 2-way internet text messaging connectivity -c) Uses existing standard non-proprietary methods and equipment. -d) Provides Interoperability with other Emergency Services -e) No external computer or modem required in the field! -f) Proven technique, available now -g) Available embedded in off-the-shelf HF transceivers -h) Bulletin QSTs (one-to-many transmissions) -i) Net (one-to-few) transmissions. -j) Provides optional verified message receipt -k) Modulation compatible with standard SSB ham rigs -l) No special IF filter, ALC, or mic level adjustments -m) Moderately robust, QSB and QRM-resistant -n) Many users can compatibly time-share same channels
DISADVANTAGES	-a) Limit 80 or 120 characters per message -b) Alphanumeric only, no binary -c) Fixed speed

TABLE 3 - DATA MEDIUM LEVEL

STATUS	EXISTING
SIGNAL TYPE	8FSK tones at 750Hz to 2500Hz
NECESSARY BANDWIDTH	1.75 kHz
OCCUPIED BANDWIDTH	2.1 kHz
SYMBOL RATE	125 Symbols/sec
BIT RATE	375 bits/sec
SNR	-3dB non ARQ -6dB ARQ
BASIS	Non-Proprietary MIL-STD 188-141 / FS-1045
FORMAT	DBM-ARQ as in PCALE software DBM- non-ARQ as in PCALE software ARQ-FAE as in Multipsk software Unproto as in Multipsk software
FUNCTIONS:	-a) Texting and Realtime "Duplex" Chat between operators -b) SMS to/from cell phones -c) Email, primarily text-based -d) Internet IM -e) Stored Messages when operator unavailable -f) Remote File storage/retrieval -g) Control of equipment or servers -h) FTP of text or binary files -i) TCP/IP or binary internet communications -j) BBS
ADVANTAGES	-a) Uses existing proven method -b) Modulation compatible with standard SSB ham rigs -c) No special IF filter, ALC, or level adjustments -d) Available now in PC soundcard programs -e) ARQ compatible with normal PC computers/soundcards -f) Provides verified message receipt -g) Bulletin QSTs (one-to-many transmissions) -h) Same signal type as Initial Access Level signal -j) Simultaneous FTP with operator duplex chat -k) Binary, Ascii, or Alphanumeric -l) ARQ requirements are flexible and non-synchronous -m) Moderately robust, QSB and QRM-resistant -n) Ready to use now -o) Does not need regulatory action
DISADVANTAGES	-a) Not currently embedded in HF transceivers -b) Requires external PC computer -c) Fixed speed 375 bits/second -e) Optimum only for small-medium files/email - f) Not fast enough for large images

TABLE 4 - DATA ADVANCED LEVEL 1

STATUS	EXISTING
SIGNAL TYPE	6PSK (6 phase positions) centered on 1500Hz
OCCUPIED BANDWIDTH	2.5kHz
SIGNAL SYMBOL RATE	2000 Symbols/sec
BIT RATE	50-2000 bits/sec variable as needed for conditions
SNR	-10dB low speed to +10dB high speed
BASIS	FS-1052 MIL-STD 188-110 Serial Tone PSK Modem adapted for Amateur Radio
FORMAT	ARQ as in RFSM-2400 or MARS-ALE Non-ARQ as in MARS-ALE
FUNCTIONS	a) Texting and Realtime "Duplex" Chat between operators -b) SMS to/from cell phones -c) High Speed Email including images -d) Internet IM -e) Stored Messages when operator unavailable -f) Remote File storage/retrieval -g) Control of equipment or servers -h) FTP of text or binary files -i) HFIP or binary internet communications -j) BBS
ADVANTAGES	-a) Uses existing proven method currently in use worldwide -b) Bandwidth compatible with standard SSB ham rigs -c) Available now in PC soundcard programs -d) High speed robust ARQ -e) ARQ compatible with normal PC computers/soundcards -f) Provides verified message receipt -g) Variable speed automatically optimized for conditions -h) Moderately robust in fading and multipath -j) Simultaneous FTP with operator duplex chat -k) Binary, Ascii, or Alphanumeric -l) PSK is very good for data transfer with ARQ -m) Utilizes maximum transmitter power signal -n) Good noise immunity -o) Good for image files
DISADVANTAGES	-a) Not currently embedded in HF transceivers -b) Requires external PC computer -c) Requires some care in ALC level adjustment -d) Doesn't conform exactly to FS-1052 standard -e) Needs regulatory action re: USA’s 300 Symbol/s limit

TABLE 5 - DATA ADVANCED LEVEL 2

STATUS	EXISTING
SIGNAL TYPE	8PSK (8 phase positions) centered on 1800Hz
OCCUPIED BANDWIDTH	3kHz
SIGNAL SYMBOL RATE	2400 Symbols/sec
BIT RATE	75-4800 bits/sec variable, as needed for conditions
SNR	-10dB low speed to +20dB high speed
BASIS	FS-1052 MIL-STD 188-110 Serial Tone PSK Modem
FORMAT	Non-ARQ and ARQ as in RFSM-2400, PCALE, or MARS-ALE
FUNCTIONS	-a) Texting and Realtime "Duplex" Chat between operators -b) SMS to/from cell phones -c) High Speed Email with images -d) Internet IM -e) Stored Messages when operator unavailable -f) Remote File storage/retrieval -g) Control of equipment or servers -h) FTP of text or binary files -i) TCP/IP or binary internet communications -j) BBS -k) HFIP
ADVANTAGES	a) Uses existing proven method currently in use worldwide -b) Conforms to Fed Standard and worldwide standards -c) Available now in PC soundcard programs -d) High speed robust ARQ -e) ARQ compatible with normal PC computers/soundcards -f) Provides verified message receipt -g) Variable speed automatically optimized for conditions -h) Moderately robust in fading and multipath -j) Simultaneous FTP with operator duplex chat -k) Binary, Ascii, or Alphanumeric -l) PSK is very good for data transfer with ARQ -m) Utilizes maximum transmitter power signal -n) Good noise immunity -o) Good for image files
DISADVANTAGES	-a) Not currently embedded in HF transceivers -b) Requires external PC computer -c) Requires Transceiver with 3kHz passband -c) Requires some care in ALC level adjustment -d) Needs regulatory action re: USA’s 300 Symbol/s limit

TABLE 6 - DATA HF-IP LEVEL

STATUS	EXISTING
STANDARD TYPE	FS-1052 STANAG-5066 Open-5066
BASIS	Non-Proprietary Federal Standard International Standard Open Standard
FUNCTIONS	-a) Interface with TCP/IP Internet -b) Interface with FTP Internet -c) Interface with Email Internet -d) Interface with IM Internet -e) Interface with Internet SMS
ADVANTAGES	-a) Uses existing proven method currently in use worldwide -b) Conforms to existing worldwide Standard -c) Runs on PCs -d) Some parts of it available for development -e) Working systems already developed by hams -f) Does not require central server or proprietary network
DISADVANTAGES	-a) Not currently embedded in HF transceivers -b) Requires external PC computer -c) Requires complex development

NOTE 1 - ARRL Seeks Comments on New HF Digital Protocol

NEWINGTON, CT, Feb 22, 2007 -- The ARRL is seeking comments from amateurs concerning development of an open-source (non-proprietary)data communications protocol suitable for use by radio amateurs over high-frequency (HF) fading paths. This is not a Request for Proposals(RFP). An RFP may or not be forthcoming depending on evaluation of the information received.

Specifically, the League is asking for comments and information on the following issues:

*

Access Method: Is Orthogonal Frequency-Division Multiplexing (OFDM) the best candidate technology, or should other competitive technologies be considered?
*

Data Rate and Bandwidth: What data rates/throughputs are achievable at various bandwidths up to 3 kHz bandwidth?
*

Adaptivity: What adaptive features should be considered, such as automatic adjustment of transmitter power, modulation waveform and coding, in order to maximize throughput and efficiency in two-way contacts?
*

Robustness: What is achievable for reliable operation at power levels typical in the Amateur Radio Service and low signal/noise and interference ratios?
*

Error control: What are the appropriate applications of error control suitable for HF channels? For example, how should Repeat reQuest (ARQ) and Forward Error Control (FEC) be applied to two-way contacts and one-to-many (roundtable and bulletin) transmissions?
*

Activity Detection: What is an effective method of determining whether a frequency is busy prior to transmission?
*

Operating System: What operating systems (such as Windows or Linux) are appropriate for Amateur Radio use with this protocol?
*

Hardware: What practical and affordable hardware platforms are suitable for amateur stations? Consider the use of personal computers with or without sound cards. Provide any information about the need for an additional "box" if needed.

Please provide the following with your response: (1) name of respondent, (2) respondent's contact information, (3) related experience, and (4) type of respondent: (individual, partnership, corporation or group). Do not include proprietary information as part of your response.

END OF DOCUMENT