Post on 16-Feb-2018
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The Stratus Solution
1.1 Codan and Transportable Radio Systems
When disasters strike, they usually happen at the worst time, in the worst location and somewhere that
no longer has communications. Transportable Radio Systems are quickly deployed ‐ with minimal
complexity ‐ to support portable and temporary communication solutions.
Codan has a long history of making customized Transportable Radio solutions for its various customers
and their many unique requirements. We have learnt over the years that each customer has a
combination of particular requirements that need to be met to make sure their system is going to be
successful in as many of their expected scenarios as possible.
The Codan Vizor is a compact, lightweight, easily deployable repeater system that operates on standard
Land Mobile Radio (LMR) radio frequencies in the VHF and UHF bands. Codan’s HiveNet is a deployable
repeater network connected together over VHF or UHF radio links to create a larger coverage footprint
than a single repeater. Extending communications over the horizon, the MRAY connects LMR repeater
systems together over huge distances using HF radio links.
Stratus combines the compact, lightweight and easily deployable characteristics of the Vizor, adds the
connected network repeater capabilities of the HiveNet and emulates the long distance connectivity of
the MRAY. Stratus goes beyond these capabilities, allowing multiple devices to be connected
dynamically through the Project 25 (P25) Digital Fixed Station Interface (DFSI) protocol.
1.2 How does a Stratus radio system work?
The Codan Stratus radio system is a self‐contained LMR repeater system that can
be used to extend the coverage of VHF or UHF radio signals over a large area and
is ideal for tactical and emergency situations. The Stratus can also be used as a
deployable base station and is operational in Analog and P25 Digital modes of
operation.
However, the power of Stratus extends far beyond that of a stand‐alone repeater
or base station. When a transportable repeater system is deployed, it creates an
“island” of communications. What is truly needed is the capability to extend the
“island” out to all corners of the tactical communications world, and create a communications “world”
encompassing all of the capabilities of an organization. A Stratus radio network accomplishes this by
leveraging existing cellular infrastructure and IT technologies to harness their power in the P25 radio
communications system.
Figure 1 ‐ Stratus Repeater
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A Stratus repeater connects to a cellular 3G or 4G Long Term Evolution (LTE) network, through the
Internet, back to the Local Area Network (LAN), where a P25 DFSI compliant console resides. The
console ties into all radio communications on‐scene at the Stratus repeater location, allowing a
dispatcher to listen and talk to the tactical team at the remote site, virtually anywhere in the world.
Stratus systems use a Virtual Private Network (VPN) to provide a secure encrypted tunnel connection for
information passed over the network.
Figure 2 ‐ Stratus Repeater into LAN over LTE using VPN
The Stratus repeater can be quickly added to an established network without any setup required by the
user. A Stratus will automatically connect into the network over the 3G / 4G LTE connection and
establish a link with the dispatch console. The Sierra Wireless cellular modem connects to the network
using Dynamic Host Configuration Protocol (DHCP).
The power of a stratus network extends far beyond a cellular connection to a single console. The power
of the P25 Common Air Interface (CAI), DFSI, 3G / 4G LTE, VPN and WAN / LAN with IP allows the Stratus
Radio Network to expand into new and powerful interoperable connectivity.
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1.3 Stratus Fixed and Tactical Servers
DFSI is a point to point connection supporting only one device at a time. The Stratus Fixed Server, based
on Codan’s Digital Link Controller technology, acts as an arbitrator for the DFSI allowing many point to
point connections. The Stratus Fixed Server will route digital audio and control signals between multiple
Stratus repeaters and DFSI consoles and also adds functionality that allows dynamic routing based on
the use of the P25 Network Access Code (NAC) or Talk Group ID (TGID).
The Stratus Fixed Server listens to all incoming data from every radio site and every console in the
network. Each connection (from site to site or console to site) uses routing rules configured in the
software to decide on the routing path (determined by NAC or TGID). The Stratus Fixed Server has the
capability to convert from any NAC to any TGID and vice versa. This allows for any combination of
mapping (affiliating) between all sites using any type of P25 code.
The Stratus Fixed Server will work in digital clear or digital secure mode and is fully capable of all routing
operations with encrypted calls. The Stratus Fixed Server will also route analog communications, but
only in a full broadcast mode (ie., Analog signal received at one site will automatically be transmitted at
all sites). DFSI (version 2) will support more analog routing (CTCSS and DCS) and will be incorporated
into the Stratus Fixed Server in the future.
Figure 3 ‐ Stratus Network with Multiple Repeaters and Consoles Interconnected using Fixed or Tactical Servers
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The Stratus Fixed Server has a Graphical User Interface (GUI) for remote configuration and monitoring of
the Stratus network, using any standard web browser with a secure login. Real‐Time Site Monitoring is
available through the GUI that displays frequently updated (< 5 seconds) system status. Priorities can be
set per site, for each NAC or TGID, to allow different users or groups higher or lower routing priority if a
signaling conflict occurs.
Figure 4 ‐ Stratus Server GUI
Some organizations have a LAN with restrictions that make it difficult or impossible to add external
servers or to use for mission‐critical communications. The optional Stratus
Tactical Server is housed in a rugged transportable case for quick
deployment anywhere with a 3G / 4G LTE signal, without the hassle of tying
into an existing LAN. The Stratus Tactical Server comes complete with a VPN
Server and has the same functionality and capabilities of the Fixed Server,
but with a limitation of 10 repeater / console connections.
P25 DFSI consoles can be connected via Ethernet directly to the Stratus
Tactical Server, or even directly into a Stratus repeater. A P25 DFSI Console
can also be connected into the cellular network with the use of an aircard. An aircard is a wireless
broadband modem used for connecting to 3G or 4G LTE cellular networks to provide roaming access to
the Internet from mobile computers.
Figure 5 ‐ Stratus Tactical Server
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1.4 Stratus Fixed Equipment and Stratus Console Gateway
Codan MT‐4E radio systems at fixed site installations can be reconfigured by the addition of a few
control modules to be a part of the Stratus Radio Network. The Stratus Fixed Sites can be fully
integrated into an existing Stratus network, allowing DFSI through the 3G / 4G LTE network. A Stratus
Fixed Site can also be connected directly to the RF Sub‐System (RFSS) / LAN through a direct Ethernet IP
interface.
The Stratus Console Gateway is a software product that translates DFSI voice traffic and control
messages to a proprietary signal used to communicate with multiple disparate endpoint devices over
the LAN. These endpoint devices could include VoIP (SIP‐based) telephony devices, legacy tone remote
consoles, other radio systems, or even a network of multiple Stratus Consoles.
Figure 6 ‐ Stratus Network with Fixed Equipment and Console Gateway
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1.5 Stratus Storm Mobile Application
The Stratus Storm Mobile Application is a free downloadable application for iOS, Windows or Android
mobile devices that allows all the same features and capabilities (including encryption) as a P25
subscriber radio. The Stratus Storm Mobile Application connects to the Stratus Radio Network through
the 3G or 4G LTE cellular network (or Wi‐Fi) and connects to the Stratus Storm Mobile Application
Gateway Software embedded in the Stratus Server. The Stratus Storm Mobile Application
communicates using the DFSI protocol and is recognized in the same way as an actual transmission from
a P25 subscriber radio.
This Stratus Storm Mobile Application allows for maximum flexibility by providing radio communications
and interoperability capability to multiple users, allowing the users to “bring your own device” (BYOD).
The Gateway Software authenticates the license for each Stratus Storm Mobile Application and
determines the number of maximum allowable users based on the number of licenses purchased. The
Gateway Software also allows the system administrator to enable remote radio features.
Figure 7 ‐ Stratus Network with Stratus Storm Mobile App
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1.6 Stratus Accessories
1.6.1 Stratus Rapid Antenna
The Stratus Rapid Antenna is a compact, lightweight and robust rapidly deployable antenna solution.
The antenna is enclosed in a mast made of composite material that transports as a flat coil then rapidly
expands into a rigid mast. The Stratus Rapid Antenna is available for VHF, UHF 400 MHz and UHF
700/800 MHz frequencies.
Figure 8 ‐ Stratus Rapid Antenna
1.6.2 Stratus Power Center
The Stratus Power Center is a 35 Ah battery housed in a compact and rugged transportable case for
power support of the Stratus Repeater. The power center provides a 12 Vdc power source to the Stratus
repeater. The battery in the power center is charged and maintained by a 15 Vdc input from an AC/DC
power supply, solar panel or vehicle. The Stratus Power Center also includes a 60 Watt solar panel made
of a rugged flexible material.
Figure 9 ‐ Stratus Power Center and Solar Panel
1.6.3 Stratus Duplexer Case
The Stratus Duplexer Case is a compact lightweight case designed to hold up to three additional mobile
duplexers, mounted on a quick‐swap panel, allowing for quick and easy frequency agile setup.
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1.7 What if there is no 3G or 4G LTE cellular coverage where the LMR system needs to be deployed?
A Stratus Radio Network can easily be interconnected with other Codan Transportable radio systems to
effectively extend the range of the P25 signal over a larger LMR coverage area, even to areas without 3G
or 4G LTE signal coverage.
Figure 10 ‐ Stratus Network with Accessories and Extended Repeater Coverage
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1.8 Radio Internet Protocol Communications Module (RIC‐M)
The Radio Internet Protocol Communications Module (RIC‐M) is a radio system interoperability solution
developed by the Department of Homeland Security (DHS), Science and Technology Directorate (S&T).
The RIC‐M is an external, stand‐alone, interface device that connects repeaters, base stations, consoles
and other RF equipment over a network using the Internet Protocol (IP). The RIC‐M converts voice and
control messages from a commonly used V.24 serial communications protocol to the P25 open‐standard
Digital Fixed Station Interface (DFSI). P25 digital communications (encrypted and unencrypted) are
supported as well as operation with other analog communication equipment.
The RIC‐M allows the Stratus Radio Network to interconnect with existing legacy equipment and
become a small or large component of the existing communications system. This allows for an easy
upgrade path away from proprietary radio systems manufactured by a single company, to an open
interface P25 radio network that can be interconnected and supported by multiple vendors, making the
communications system truly interoperable. The RIC‐M will allow users to continue to use installed
legacy systems, while upgrading to more economical equipment or systems with better capabilities and
options.
The RIC‐M allows the Stratus Radio Network to be connected to legacy equipment such as a Voting
Comparator, Key Management Facility or other vendors’ RF equipment.
A Voting Comparator can be used to evaluate the incoming digital or analog radio signals and pick the
best quality signal from multiple sites. Once the best quality signal is determined, it can then send the
signal to P25 DFSI (or legacy) consoles and/or Stratus repeaters. The Voting Comparator also has the
ability to send the signal to a single radio site or to multicast to many radio sites (P25 Multicast
Capability).
A Key Management Facility (KMF) is a complex software program that is connected to a P25 radio
system and is used to transmit, store and manage P25 encryption keys. Agencies and organizations
utilize a KMF for key management when their radio network includes a large number of subscriber
radios or numerous groups requiring different levels of secure encryption. A KMF transmits the
encryption keys and receives radio authentication, using over‐the‐air rekeying (OTAR) packet data
through the Stratus Radio Network and over the Common Air Interface, to and from P25 subscribers.
The RIC‐M also allows seamless integration of the Stratus Radio Network into an existing radio network
that uses the V.24 serial communications protocol. This allows organizations to replace failed or aging
radio systems with lower cost, open standards equipment from other manufacturers.
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1.9 Complete Stratus Radio Network Diagram
Figure 11 ‐ Complete Stratus Radio Network Diagram
This diagram shows all of the capabilities of a Stratus Radio Network.
Ask your Codan representative, “what more can the Stratus Radio Network do for me?”
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1.10 Stratus Radio Network Key Features and Benefits
Utilizing leading technology from Codan, the Stratus Radio Network has unique features and benefits
unparalleled in the market, these include:
• 3G and 4G LTE Connectivity: The Stratus Repeater uses a Sierra Wireless cellular modem to
connect the MT‐4E series radio systems to existing 3G and 4G LTE cellular networks, allowing
the repeater to become part of a much larger wide area network.
• Frequency Agility: Internal “quick change” duplexer mounting capability and easy to use Service
Software allows for frequency agile programming and setup of up to 32 channels.
• Integrated LTE Antenna: The Stratus Repeater uses a compact, covert profile diversity antenna
mounted inside the Stratus enclosure.
• Ease of Use and Rapid Deployment: Instant communications as easy as turning on the repeater,
connecting the antenna and power source, and then talking. After initial configuration, the 3G /
4G LTE connection is automatic.
• P25 Interoperability: Interoperable with P25 subscriber radios and repeaters from all P25
supported vendors.
• Environmentally Tough: With an IP65 rating and an industry leading compact size and weight,
it’s easy to transport while being tough, rugged and water resistant.
• Secure Encryption: Inherently repeats and transports all P25 encryption (AES‐256) both over the
network (cellular and WAN/LAN) as well as over the air to P25 subscribers, to ensure your
communications are confidential and secure. With VPN, communications are effectively double‐
encrypted over the network (VPN encryption and P25 encryption).
• Multi‐Mode capability: Can operate as a P25 digital or analog, repeater or base station (includes
a lightweight OTTO headset).
• Transparent P25 Repeater: Transparent communications with a true digital connection between
all devices on the Stratus Radio Network.
• High Power Output: With up to 30 Watts of RF power output, the Stratus repeater can perform
with exceptional radio coverage. A Low/High power selection switch can be used for down to 15
Watts output.
1.11 Stratus Radio Network Summary
The Stratus Radio Network is a unique and innovative communications solution allowing for wide
ranging interoperability between tactical units, first responders and many other mission critical users.
Quick to set up and easy to use, it provides on‐the‐ground instant communications when seconds count.
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2. P25 and LTE: A Powerful Team
2.1 What is LTE?
Long Term Evolution (LTE) is the project name of a high performance air interface for cellular mobile
communication systems. It is a 4th generation (4G) technology designed to increase the capacity and
speed of mobile telephone networks. It is a project of the 3rd Generation Partnership Project (3GPP), a
collaboration of global telecommunications standard development organizations.
Unlike older cellular technology that uses Code Division Multiple Access (CDMA) and Time Division
Multiple Access (TDMA), LTE uses Orthogonal Frequency Division Multiple Access (OFDMA) for the
downlink (tower to user equipment), and a discrete Fourier transform spread of OFDMA that generates
a Single Carrier Frequency Division Multiple Access (SC‐FDMA) signal for the uplink (user equipment to
tower). SC‐FDMA has a lower power ratio that reduces battery power consumption and improves uplink
coverage. OFDMA is a multi‐carrier scheme that allocates radio resources to multiple users and assigns
each user the bandwidth needed for their transmission
Multiple In, Multiple Out (MIMO) is used to provide better signal performance and higher data rates by
the utilization of the multipath reflections that exist. MIMO utilizes the multipath signal propagation by
connecting multiple antennas at the transmitter and receiver and using significant processing power to
take advantage of the different RF signal paths. MIMO uses multipath reflections constructively, rather
than allowing it to destructively interfere, as it can on standard LMR equipment.
The higher signal‐to‐noise ratio at the receiver enabled by MIMO, along with OFDMA, provides
improved coverage and throughput, especially in dense urban areas. LTE also has low data transfer
latencies (less than 5 ms latency for small IP packets in optimal conditions), as well as lower latencies for
handover and connection setup time than with previous radio access technologies.
LTE has flexible duplex methods; both Frequency Division Duplex (FDD) and Time Division Duplex (TDD)
are valid spectrum allocations. This allows LTE to accommodate various RF channel bandwidths in the
available spectrum. The RF channel bandwidths allowed are 1.4, 3, 5, 10, 15 and 20 MHz. The most
common duplex method being used is FDD which uses separate frequencies for downlink and uplink in
the form of a band pair. TDD uses one single range of frequencies in a frequency band, but that band is
segmented to support transmit and receive signals in a single frequency range.
LTE is based on a flat IP architecture and supports peak data rates of up to 100 Mbps on the downlink
and 50 Mbps on the uplink when using a 20 MHz channel bandwidth with a single transmit antenna at
the user equipment, and two receive antennas at the Base Station. This can be increased up to 300
Mbps downlink and 75 Mbps uplink when using four transmit and four receive antennas.
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The IP‐based network architecture, called the Evolved Packet Core (EPC) is designed to replace the GPRS
Core Network, and supports seamless handovers for both voice and data to cell towers with older
network technology such as W‐CDMA, GSM, UMTS and CDMA2000 and other non‐3GPP systems.
The different LTE frequency allocations or LTE frequency bands are allocated numbers. Currently LTE
bands 1 to 22 are for paired spectrum (FDD), while LTE bands 33 to 41 are for unpaired spectrum (TDD).
Below is a partial list of LTE frequency band allocations along with some countries that currently use
those allocations.
Band Uplink (MHz)
Downlink (MHz)
Width of Band (MHz)
Duplex Spacing (MHz)
Band Gap (MHz)
Duplex Mode
Prevalent Countries
3 1710 ‐ 1785 1805 ‐1880 75 95 20 FDD Australia & New Zealand
4 1710 ‐ 1755 2110 ‐ 2155 45 400 355 FDD USA & Canada
5 824 ‐ 849 869 ‐ 894 25 45 20 FDD Australia
7 2500 ‐ 2570 2620 ‐ 2690 70 120 50 FDD Australia & Canada
12 698 ‐ 716 728 ‐ 746 18 30 12 FDD USA
13 777 ‐ 787 746 ‐ 756 10 ‐31 41 FDD USA
14 788 ‐ 798 758 ‐ 768 10 ‐30 40 FDD USA ‐ FirstNet
17 704 ‐ 716 734 ‐ 746 12 30 18 FDD USA
28 703 ‐ 748 758 ‐ 803 45 55 10 FDD Australia & New Zealand
40 2300 ‐ 2400 100 x x TDD Australia
Figure 12 ‐ LTE Frequency Bands
Figure 13 – LTE Frequency Band Information Diagram
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2.2 What is FirstNet?
The United States First Responders Network Authority (FirstNet) was created in 2012 as an Independent
Authority within the US National Telecommunications and Information Association (NTIA) to provide
public safety agencies with a nationwide broadband digital network dedicated to public safety.
The intent of FirstNet is to provide a US wide broadband data network that will enable public safety
agencies access to high speed data for items such as video feeds, detailed maps, biometrics for first
responders and on‐scene victims, access to virtual medical teams and other emergency response
specialists, detailed building and location blueprints, access to full Material Safety Data sheets for
appropriate chemical responses and full connectivity for Incident Command posts.
FirstNet is based on the 4G LTE standard and will operate in LTE Band 14. A requirement of FirstNet is to
provide 99 percent coverage of the populated areas and the National Highway System. Tens of
thousands of tower sites will be required to achieve this coverage and the sites and network are
required to be hardened for resiliency and redundancy against Earthquakes, Hurricanes, Tornados and
Terrorism.
FirstNet is not intended to replace LMR, instead it is designed to provide mission‐critical data and
applications to augment the voice capabilities of land mobile radio (LMR) networks.
FirstNet plans to offer Voice over LTE (VoLTE) for daily public safety telephone communication. VoLTE is
the ascendant method for delivering standardized voice and Short Message Service (SMS) text messages
over LTE networks. The standards for VoLTE are still under development and will determine the
functionality and performance requirements for mission critical voice. FirstNet is actively involved in the
standards setting process, but the latest date for VoLTE standards to be finalized is 2018.
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2.3 What is DFSI?
The conventional Fixed Station Interface (FSI) is a P25 open interface that provides for communication
between a Fixed Station and either an RF Sub‐System (RFSS) or a Console Sub‐System.
The FSI defines both an Analog Fixed Station Interface (AFSI) and a Digital Fixed Station Interface (DFSI).
Either one of these interfaces can be used to connect to a fixed station operating in analog, digital or
mixed mode. The AFSI configuration is 2 or 4‐wire audio with E&M or Tone Remote Control.
The DFSI defines a set of mandatory messages, supporting analog voice, digital voice (clear or encrypted)
and data (under development). These messages are in a standard format passed over an IP based
interface. Manufacturers can enhance this functionality using manufacturer specific messages.
The physical layer is an Ethernet 100 Base‐T with an RJ45 connector and the network layer is IPv4. The
DFSI utilizes UDP for control information and RTP on UDP for voice information. Digital voice
information is IMBE™ and analog voice information is PCM audio.
Since DFSI is an IP based interface, DFSI signaling can be easily passed through an LTE network, which is
based on IP architecture. Analog voice, Clear or Encrypted voice, manufacturer messages and
proprietary data can all be passed transparently through the LTE (or 3G) network.
Figure 14 ‐ DFSI Protocol Suite
Application
Link
Network
Transport
Physical
ControlProtocol
IPv4
UDP
Ethernet 100 Base-T withan RJ-45 connector
or other industry standard
RTP RTCP
VoiceConveyance
Protocol
Internet Architecture Layers DFSI Protocol Suite
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2.4 What is VPN?
A Virtual Private Network (VPN) is a network technology that creates a secure network connection over
a public network such as the Internet or a private network owned by a service provider, like a public 3G
/ 4G LTE network provider. VPN technology is used to enable remote users to securely connect to a
private network. A VPN creates a Wide Area Network (WAN) to securely connect multiple sites over
large distances.
IP security (IPSec) is a VPN protocol that secures the transport of data traffic over a public network.
IPSec traffic can use either transport mode or tunneling to encrypt data traffic in a VPN. Transport mode
encrypts only the message (payload) within the data packet while tunneling encrypts the entire data
packet.
A firewall between the client and the host server requires the remote user to establish an authenticated
connection with the firewall using a unique identification and a password. VPN technology also employs
encryption algorithms such as AES‐128 and AES‐256, among others, to ensure secure data integrity and
privacy.