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Satellite Communications - Applications,
Testing, & Test Tools

Ever since the discovery (invention?) of satellites by Sir Arthur C. Clarke, their use has brought hope, prosperity, entertainment, and knowledge to humanity.  The future is equally optimistic.  The scope of this paper, however is more modest - to take a look at some of the current trends in satellite communications applications, testing, and test tools.


Satellite Applications

Referring to the diagram above, we review some of the unique aspects of the satellite communications channel, especially of geosynchronous satellites:

  • wide area connectivity almost anywhere and everywhere in the footprint of the satellite beam - thus applications such as video broadcast and mobile phone are possible for large populations

  • almost instantaneous network deployment, with no wired infrastructure required - thus voice, data, and video applications can be available almost immediately

  • propagation delay of about 250 milliseconds (up + down) and if you consider round trip, then almost 500 milliseconds

  • an RF channel that is more than 36,000 km long before amplification or repetition - this results in a free space path loss in the range of 190 to 208 dB!! (for frequencies in the 2 GHz to 15 GHz range).  In the older days this was a show stopper, but now - high gain antennas, power amplifiers, ultra-low-noise receiver sensitivities and such that this is no longer a problem!

  • variable channel characteristics that can be totally absent or severely degraded as during sun outages, or bursty errors during rain and snow, or during clear sky low random/gaussian errors if power/signal constrained

  • limited bandwidth since the available electromagnetic spectrum must be shared among all users - one area of world politics in which engineers and scientists have actually cooperated without acrimony!

The above characteristics present challenges and opportunities. This article discusses some of these.


Test Tools, and Requirements for Satellite Backhaul for Mobile Networks

A typical complete wireless network lab suite by GL Communications is shown below -

Visit Wireless Core Networks LAB Solutions 2G, 3G, & 4G for more details.


Satellite Backhaul for Mobile Networks Mobile Core Network Simulator

Satellite Delay Measurement over Voice, T1 E1, Datacom, T3 E3, & Optical Interfaces

  • Test the echo cancellers or simulate the echo cancellation across the network to ensure error-free voice communications.  GL provides many tools to test and measure echo canceller performance - echocan.html.

  • Emulate ISDN / SS7 / SIP networks in the lab, simulate delay, and error rates to measure real life performance of data applications. GL’s Signalling and Traffic Emulation tools are widely used in the industry for such simulations - http://www.gl.com/signaling-and-traffic-simulator.html.

  • Satellite Delay Measurement IP-based satellite mobile backhaul networks - these networks are characterized by the service level agreement (SLA). An Ethernet/IP tester used in satellite communications must support BERT, RFC 2544, and Y.1564 SLA tests at minimum.  GL’s Ethernet Tester are precisely designed to handle these testing requirements - http://www.gl.com/telecom-test-solutions/testing-ethernet-ip-wan-networks.html.

Satellite Delay Echo Cancellation in Satellite Networks
   
Delay Measurement in Satellite Networks Delay Measurement in IP over Satellite Networks


Satellite Delay Compensation Application

 

 

 

 


Satellite Delay, Error, Jitter Simulation


 


Voice and Data Quality Testing of Satellite Channels

  • A versatile test suite by GL allow users to send and receive the simulated voice and data traffic (as seen in real-time) over satellite network and perform the QoS measurements using ITU-T standard – PEQSQ and POLQA. These capabilities are provided within a portable-single-box solution with the flexibility of connecting to and between any network, any service, and any interface - http://www.gl.com/eMedia/network-wide-voice-and-data-quality-monitoring.html.








Testing Satellite WAN Links

  • Application performance over WAN networks can be highly sensitive to bandwidth, latency, jitter, loss, and other WAN impairments. Testing these applications on the local network generally fails to identify critical issues that impact the end user experience. Fortunately, GL provides a new generation of WAN network emulation appliances that makes it simple and affordable to test applications in the lab under real-world conditions, ensuring smooth roll-outs of new applications and helping to optimize the performance of the applications for the end-users. Visit
    IPLinkSim™ - WAN Emulation with PacketExpert™
    ,   IPNetsim™, and IPNetSim™ Handheld for more details.








Testing DCME (Digital Circuit Multiplication Equipment)

  • The DCME testing, analysis and verification can be performed with DCME monitoring software such as GL’s DCME analysis software http://www.gl.com/dcme.html. Additionally, a Facsimile subframe analysis software may be used that permits bit level analysis and verification of fax data sub-multiplexing on the DCME output bearer signal.

 
 
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