hfgcs digital hf developments and concepts · hfgcs digital hf developments and concepts 7 february...

HFGCS Digital HF HFGCS Digital HF Developments and

ConceptsConcepts

7 February 2008

Gary BoesdorferRockwell Collins(972)[email protected]

© 2008 Rockwell Collins, Inc. All rights reserved.

HFGCS Description

• High Frequency Global Communication System, f.k.a. SCOPE Command

• Network of 13 worldwide, high power, HF ground stations• Operations centralized at CNCS at Andrews AFB• United States Air Force program, HFGCS SPO at Tinker AFB• Lead Command

– Air Mobility Command

© 2008 Rockwell Collins, Inc. All rights reserved. 2

HFGCS Station Locations

CROUGHTON

ELMENDORF

LAJESWEST COASTOFFUTT

CROUGHTON

YOKOTA

SIGONELLAANDREWS

HAWAII

Central Network Control Station DIEGO GARCIA

GUAMPUERTO RICO

Control StationASCENSION


HFGCS Missions

• Primary command and control for mobility air forces• Presidential and executive DOD support • National Command Authority dissemination of Emergency War

Orders through Emergency Action Messages – Single Integrated O ti l PlOperational Plan

• Spanish speaking network between US, Southern and Central American Air Forces

• Global Humanitarian/NATO Mission support• Global Humanitarian/NATO Mission support• High Frequency Secure Email to the AWACS Fleet• US Navy

Voice data broadcast Link-11– Voice, data broadcast, Link-11

• Space Command– Eastern/Western test ranges support


Typical Station Node

High Power HF Communications

Receiver T itt Site: 2-30 mhzTransmitter Site: 4 kw

DISA Network (GIG)Control SiteIntersite Communication via

Microwave or Cable


Microwave or Cable

Basic Features

• 10 to >30 radio levels at each station with Navy consolidation

• Automatic Link Establishment (ALE)G ALE t M lti l

• Automatic Air/Ground Phone Patching

• Group ALE supports Multiple Simultaneous ALE Calls per Station

• Scanning Receivers/Voice Detection with Automatic Handoff• World-Wide All-Frequency Broadcasts (Within 60 Seconds)• Web-Based Automatic Ground/Air Phone Patching (with ALE)• HF Email• Ground Routing Automatically Locates Best Station For ALE Call

– Knowledge of Actual Aircraft Position Not Required


WebCall Feature

• Command Center Able to Establish Voice Comm with ALE-Equipped A/C Through Web Browser– No HFGCS operator

involvementA t ti ti t – Automatic routing to best station

– Requestor telephone called when ALElink established to complete phonepatch

• Accessibility Via ccess b ty aNIPRNET

• Future Availability Via SIPRNET


HF Email Capabilities

• Both secure (SIPRNET) and non-secure (NIPRNET) networks• Forwards standard email between ground network users and

mobile nodes over HF• Best station routing used for ground-to-air deliveries• Messages queued for later delivery if immediate delivery not

possible• Standards-based implementation

2G ALE f li k t bli h t– 2G ALE for link establishment– Up to 9600 bps modem (STANAG 4539, MIL-STD-188-110B)– STANAG 5066 & CFTP client used for reliable over-the-air data

delivery y– Standard SMTP email protocols into the ground network

• Adding ability for multiple ALE networks in each HF email domain


Current Activities

• NCS-West expected to be operational by end of calendar 2008– Both NCSs to be capable of using and controlling assets at all

stations• Audio and data connectivity between NCS and stations

migrating to “over IP”• AoIP for voice & modem audio connectivity between NCS and

station– Audio Access Points (AAP) at station provide audio for up to 10

simultaneous users for each radio circuit using AoIPsimultaneous users for each radio circuit using AoIP– Sets the stage for future user access directly to station via IP

without NCS access• Serial, synchronous data over IP

Q9604 HF modems at station accept IP data & control – Q9604 HF modems at station accept IP data & control – For HF Email, S9600 at NCS-E converts serial-to-IP to station

• Studies performed for implementation of digital voice & mobile IP over HF


Digital Voice Developments

• A two stage digital voice program was recommended in a just completed study– Stage 1 implements a clear voice capability– Stage 2 implements secure voice capability

Stage 1 clear voice implementation• Stage 1 clear voice implementation– Next step is proof of concept demonstration– Ground Gateway at the NCS performs PCM-to-MELPe transcoding– HF modem located at station with IP connectivity to Ground HF modem located at station with IP connectivity to Ground

Gateway– Supports operator voice as well as phone patch operation & voice

broadcast at NCSN d ith MELP di it l i– Need users with MELP digital voice

• Ground tactical community already using• Not yet in airborne community


Digital Secure Voice Considerations

• End-to-end encryption desired, i.e. mobile-to-telephone, bil t tmobile-to-operator

• Current telephone (STU-III/STE) and HF radio voice cryptos (ANDVT) are not interoperable – Interoperation requires decrypt & interconnect baseband audiop q yp

• Secure Communication Interoperability Protocol (SCIP) envisioned as the protocol to link users regardless of transport– 2400 bps MELP required

SCIP capable telephones currently available– SCIP capable telephones currently available• STE• Cell phones

– SCIP not yet implemented for two-way radio opsVi ANDVT C t M d i ti (VACM) l ki • Vinson ANDVT Crypto Modernization (VACM) program looking at replacement for Vinson & ANDVT cryptos– VACM initial requirements do not include SCIP– SCIP needs to become a VACM requirement


The Need For Mobile IP over HF

• Primary objective is to provide access to IP-based services on the SIPRNET/NIPRNET to mobile users

• Potential Users– AF Airborne (AWACS, B-52, AMC fleet, JSTARS, etc.)

N i b (P 3E E 2C)– Navy airborne (P-3E, E-2C)– Ground mobile users

• Applications - currently support HF email but need others:– IRC Chat– IRC Chat– MIL-STD-3011 JREAP– FTP– SMTP– NetMeeting– others


Joint Airborne Networking Vision

• HFGCS can serve as an HF ground entry point to terrestrial networks for airborne and other mobile usersnetworks for airborne and other mobile users

HiHi


Graphic from Joint Airborne Network Services Suite Functional Description Document, Version 1.0, 1 Jun 2006

Architecture Drivers

• Primarily support mobile-to-ground traffic, not mobile-to-mobileG d t ti t G d E t P i t (GEP) f bil d– Ground station acts as Ground Entry Point (GEP) for mobile nodes

– Hub-spoke architecture• HF may not be the only pipe

– Airborne platforms have limited bandwidth Na o band SATCOM BLOS UHF LOS HF BLOS– Narrowband SATCOM BLOS, UHF LOS, HF BLOS

– Airborne integrators desire to use all available pipes simultaneously– Limits ability to provide application layer proxies

• Full period connections required by some applicationsNeed method for mobiles to join/unjoin network– Need method for mobiles to join/unjoin network

• TCP Performance Enhancing Proxy needed• Dynamic IP address mechanism required• KIV-7 crypto for over-the-air encryption• Skywave propagation

– Frequencies for mobile-to-ground may not support mobile-to-mobile– Need to optimize modem data rate for each mobile-to-ground link

• IPv4 & IPv6


Each Station Can Support Multiple HF Subnets

Subnet 3Subnet 3 Subnet 3

Subnet 2

Subnet 3

Subnet 2

Subnet 1

StationY

Subnet 1

StationYX


Preliminary Solution

• Multiple HF subnetworks for each station– e.g. 13 stations x 3 freqs per station = 39 HF subnetworks– Frequencies can be reused based on station separation – Frequencies may change based on time of day

E h bil d b f l HF b t• Each mobile node a member of only one HF subnet• Mobile node directed net entry and departure• Mobile IP address management and routing based on RFC 3344

and as modified by the JCAN program for subnet registrationand as modified by the JCAN program for subnet registration– Home agents, foreign agents

• Routing between nodes performed at Layer 3


Items for Further Study

• TCP PEP Selection– Navy HFIP does not use any TCP PEP– AF JCAN uses modified SCPS-TP– Don’t know how well SCPS-TP will work when subjected to variable

throughput delays– Have recommended performance evaluation of SCPS-TP & other

PEPs• MAC Protocol Considerations

– Skywave connectivity between mobile nodes & ground stations Skywave connectivity between mobile nodes & ground stations frequently results in inability of mobile nodes to hear each other

– Ground station uplink bandwidth needs to be comparable to total bandwidth of all mobiles

– Must support adaptive data rates between ground station & mobilesMust support adaptive data rates between ground station & mobiles– Must support network join & unjoin by mobile nodes– Must support adaptive transmission slot size for each node based

on amount of queued traffic


MAC Candidates

• STANAG 5066 E2 defines two MACsA K CSMA– Annex K CSMA

• Works best for lightly loaded networks where all nodes can hear each other– Annex L HF Token Ring Protocol

• Designed for ring topology vs. hub-spoke• Frequent token relaying due to lack of connectivity between mobile nodes limits q y g y

network size to 2 mobiles plus 1 ground station• Frequent lost tokens in skywave environment reduces effective network throughput

• Remaining MAC Candidates to be modeled– Centrally managed Adaptive TDMA protocol

• Variable size slot assignments can be made based on the bandwidth needs of the • Variable size slot assignments can be made based on the bandwidth needs of the mobile node as well as the data rate the channel should support.

• Ground station allocates and broadcasts slot assignments to mobile nodes– Centralized Token Management Protocol (CTMP)

• Similar to polled networkG o nd station passes token to each mobile node g anting ight to t ansmit fo a • Ground station passes token to each mobile node granting right to transmit for a predetermined amount of time

• Lost token recovery time minimized since tokens only passed between GEP and mobile nodes.

– Selected protocol can be added to STANAG 5066


hfgcs digital hf developments and concepts · hfgcs digital hf developments and concepts 7 february...

Documents