ERA Key System Technologies for future satellite …...Infrastructure may be intentionally blocked or jammed May not be unavailable following a natural disaster / terrorist incidence

Key System Technologies for future satellite mobile systems

R A Pearson and M W Shelley, ERA Technology Ltd

2 Antenna and Electronic Systems

Presentation Overview

Evolution of Ka-band satellite systems for mobile comms

Advantages / disadvantages of these systems

Key antenna technology issues

ERA work in Ka-band for mobile applications

S-band satellite systems

Overview of new S-band systems and applications

Ancillary Terrestrial Component

Use of an Ad-hoc Terrestrial Component for disaster recovery, security & humanitarian applications

ERA demonstration programme

Evolution of Ka-band satellite systems for mobile communications Systems


Why Ka-Band?

Greater available spectrum

Smaller terminal equipment

Less inter-satellite interference

In the mobile environment, simpler antenna technology due to the use of circular polarisation


Why not?

Higher cost of equipment

Fewer high power satellites

Greater link losses

Wide frequency separation between TX and RX, creating significant antenna challenges for mobile systems


Ka-Band satellite segment

50 Ka-band satellites in orbit, 34 are active.

Most use old-fashioned “bent-pipe” technology

New satellites are being designed and built using on-board processing (e.g., multi-beam antennas with flexible antenna pointing systems)

frequency re-use

increased capacity

reduced transponder costs

Eutelsat Ka-Sat

multi-spot satellite providing good QoS at an affordable price

80 spot-beams, offering capacity equivalent to 10 Ku-band satellites

charges reduced by factor of eight compared to Ku-Band

Launch scheduled for 2010


Ka-Band satellite segment

Avanti Communications Hylas

two-way data communications for:

Resilient, ultra-high speed corporate networks

Two-way broadband access services

IPTV platform distribution

Ka-band Interactive TV return channel

HylasOne launch scheduled for 2009


Target markets

emergency services (e.g., humanitarian disaster relief)

homeland security

broadcasting

military communications


Fixed antennas for Ka-Band

No problem……


Mobile antenna solutions

Given the widespread need for low profile and small size, this is probably the most critical ground terminal component

Key challenges:

accommodating wide frequency separation in single aperture

achieving hemispherical or near hemispherical coverage

Opportunity for smaller mobile and on-pause broadcast

Air transport, also UAV (civil & military)


Circular reflector

Advantages

Simple design

Lightweight reflector, allowing high dynamic performance

Simple dual band operation

Full hemispherical coverage possible

Uniform system performance for all locations

But …

Not low profile (typically > 20”)


Elliptical reflector

Design options

Dual offset for compactness

Single offset for simplicity

Advantages

Lightweight reflector, allowing high dynamic performance

But …

Difficult to control illumination and efficiency

Medium height profile (typically 15-18”)

Scan limitations


Fixed beam array

Fixed beam array, mechanically steered in two planes

Advantages

Highly adaptable geometry

Excellent control of azimuth illumination

Simple to balance for high dynamics


Low profile (6-10”) – radome dependent

But …

Complex feed structure

Difficult to configure for Ka-Band TX and RX

ERA Ku-band system


Cylindrical reflector

Offset reflector with azimuth array feed

Advantages

Highly compact geometry

Very high efficiency

Excellent control of azimuth illumination & sidelobes

Simple to balance for high dynamics


But …

Complex array feed

Low/medium height profile (10-12”)

ERA Ku-band proof of concept aperture


Hybrid flat plate arrays

Cobham Ku-band “G2” dual aperture hybrid array: 3” height

Azimuth rotation; elevation scan without change of profile

Advantages

Generally good control of

azimuth illumination

Ultra-low profile 3” / multi-panel 6-8”

Single band designs

But …Variable elevation pattern

Limited instantaneous

bandwidths (frequency scan)

Coverage limited close to

horizon (typically > 20°)

Complex mechanical actuation

Poor elevation radiation patterns for multi-panel


Phased arrays

Electronic scan in two planes “holy grail”

Advantages

Excellent radiation patterns

Solid state design

high dynamics/multibeam

Ultra-low profile

But …

Two aperture required for RX/TX operation; wideband studies

Order of magnitude more expensive than other solutions

Coverage limited towards horizon (> 20° above horizon)

Complex RF electronics and control circuitry

ERA proof-of-concept Ka-band phased array tile (+/-70°, 40% bandwidth)


Antenna developments needed

Launch Products:

Low profile reflector systems

Future:

Hybrid antennas using single electronic scan

Dual band apertures with full electronic scan

ERA development of Ka-band demonstrator for use with Hylasstarted April 2008

Based on cylindrical reflector

Modular upgrade to Ku-band Spitfire system

Further R&D needed to advance the Ka-band tile technology

S-band Satellite and TerrestrialAd-hoc Mesh Networks


The case for S-band

Other bands:

L-band systems provide modest data rates (<500Kbit/s)

Require high gain antennas to realise higher data rates

Iridium: global coverage, but modest data rates

Ku-band systems: Mbit/s data rates but large antenna terminals

Ka-band system: Mbit/s data rates, similar terminals (rain fade)

A new generation of S-band satellite systems being developed:

Video and multimedia services – mainstream market

Emergency service use – niche market

Handheld / very small terminals:

Video and interactive services

Adjacent band to terrestrial mobile systems – dual mode handsets

Auxiliary Terrestrial Component (ATC) proposed for urban areas


Ancillary Terrestrial Component (ATC)

Urban areas: good terrestrial coverage – fixed sites link to satellite and link to mobile via terrestrial infrastructure; notyet developed – business case (will it fly?)

Rural areas: limited coverage – direct link to satellites


Competitor Service Providers

Inmarsat Global Ltd; established player – ATC authorisation from FCC

Iridium; Next - improved data rates – ATC authority from FCC

Globalstar – next generation – ATC authority from FCC

Terrestar/TMI

Plans for 4G (satellite and terrestrial)

Terrestar-1; spots -CONUS, Canada, Alaska, Hawaii, Puerto Rico

ATC for urban canyons, dense forests, areas where will be blocked

Mobile Satellite Ventures; ATC authorisation

MSAT-1 & MSAT-2 aim to deliver mobile wireless voice & data

Public safety, security, fleet & asset tracking in U.S. & Canada

ICO Global Communications

Created in 1990’s out of a programme called Project 21

MEO 1st satellite (UK entity) – ground infrastructure, 10 satellite in storage

First GEO (US entity); launched in April 2008

Eutelsat/SES

Supported by ARTES

W2A satellite in 2009


ICO S-band: CONUS and MEO

GEO; launched 14th April MEO; initial satellite in orbit

Future constellation illustrated


Mobile Services

Example services (ICO)

ERA was involved in Ku-band TV to car – large antennas required

New S-band service only requires low gain terminal antennas

$15-25 per month subscription


Ad-hoc Terrestrial Component (Ad-TC)

Could be made compatible with ATC but will function independently

Why is this important?

ATC may not develop

May not be available in a given region

Infrastructure may be intentionally blocked or jammed

May not be unavailable following a natural disaster / terrorist incidence

Ad-hoc network will:

Extend coverage in urban areas, even into collapsed buildings and underground train systems

Can be used independent of satellite if the link cannot be formed

Will enable multiple groups to be networked together or backhauled to a remote operations centre

Will enable talk-through multiple radio and satellite hops

Provide data transfer via an IPv6 overlay


Emergency & Disaster Recovery

Essential voice and data communications

Fire Rescue

Chemical and Biological Hazards

Collapsed sites


Disaster Life Cycle Management

Stage 1: Immediate: Rapidly deployable, highly portable, small,lightweight equipment

Ease of use – non technical users

Voice & data – voice & SMS contact with HQ

Internet & VPN – initial access to emergency management application

Stage 2: 48 hours: Networked communications with a high level ofinteroperability

Voice & data – on-going coordination

Internet & VPN – increasing activity via emergency management – higher data

Stage 3: beyond 48 hours: Longer term installations

Voice & data – on-going coordination

Internet & VPN – heavy traffic via emergency management systems

Technical operators

Humanitarian life cycles are typically much longer, but “disaster” area can be huge (size of a country)


How does an ad-hoc network work?

Radios talk with each other via other radios in the group

No master radio – dynamically finds radio at “centre” of mesh

Range rapidly reduces in urban or disaster conditions:

Inside buildings/collapsed structures, underground, inside-to-outside communications

Satellite link will generally fail under such circumstances

Combined satellite/terrestrial provides local & reach-back communications

Not infrastructure dependent

User A User B

2.4GHz Ad-hoc Mesh Network

Node 1

Node 3

Node 5

Node ANode

B


Self-adaptingmesh network

Self-healing

Mesh network nodesoffer potential to extend range

ERA Ad-hoc Mesh Radio

Emergency Scenarios:- Collapsed buildings

- Mines / Caves / Metro- Fires and chemical hazards

- Outdoor-to-indoor connectivity


Initial Ad-hoc Mesh Trials

Initial ERA radio trials at 2.4GHz undertaken in US using mesh network radio

ERA trials in Centre for National Response – network of mines

Indicate terrestrial coverage maintained inside-to-outside


Vision: Ad-TC with satellite connectivity

Separate ad-hoc groups can communicate:

Terrestrially with each other within local ad-hoc mesh

Terrestrially mesh-to-mesh when in range

Via satellite between ad-hoc mesh groups

Via satellite to control centre/web – single link possible

No dependence on ANY terrestrial infrastructure

Satellite Gateway:

voice or data to control

centre or web access

One or more radios in mesh is satellite enabled/ linked to satellite

modem

voice & data enabled handheld IPv6 radios

Ad-hoc mesh 1

Terrestrial link up to

~1kmIn-building comms

Ad-hoc mesh 2


Conclusions

S-band offers:

Mainstream multimedia services, e.g. to cars – removes need for large Ku-band antennas

Convergence between terrestrial and satellite communications

Emergency and Disaster Recovery use – EU allocated spectrum

Question marks about the commercial viability of ATC

Large infrastructure investment - sense of deja-vu

Satellite with Ad-hoc Terrestrial Component (AdTC):

Provide seamless connectivity for emergency services, NGOs, Govt users; local & global

Fulfils niche disaster recovery applications

Interoperable with ATC, but not dependent on it


Future Work

Further development of mesh network technology is required to demonstrate:

Dual mode terrestrial-satellite connectivity

Voice and data

In-building/outdoor connectivity

Enhanced network connectivity and scenario specific operation

Benefits of mesh network nodes

IPv6 will be critical as an overlay for such networks

ERA started a project April 2008 to adapt its military ad-hoc radio technology, add IPv6 & develop functionality for disaster management application & link to satellite system

Aiming to demonstrate with S-band satellite as part of a hybrid terrestrial / satellite network for humanitarian application in 2009

Have interest for trial by humanitarian charity

Documents

ERA Key System Technologies for future satellite …...Infrastructure may be intentionally blocked or jammed May not be unavailable following a natural disaster / terrorist incidence