Frost & Sullivan takes no responsibility for any incorrect information supplied to us by manufacturers
or users. Quantitative market information is based primarily on interviews and therefore is subject to
fluctuation.
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© 2002 Frost & Sullivan www.frost.com

Globalstar and Iridium: A Side-by-Side Performance Comparison

 

Executive Summary

Satellite phones are not a trivial investment. The cost of the phone, the per-minute charges
and the phone's applicability to each end user's needs must be carefully weighed against the
user's telecommunications requirements. A short search will show that there is ample
evidence of a decline in the cost of handsets and per-minute charges. Fortunately, this trend
is expected to continue. Nonetheless, potential customers for satellite phones have had
difficulty in obtaining significant comparative data on how each satellite phone system
performs. The marketing materials provided by the service operators are important sources
of information, yet nothing can really measure up to the ability to test each system
side-by-side in a real world environment.

The following white paper is just that, the results of a rigorous testing of the true functionality
of the latest equipment and services offered for the Iridium and Globalstar satellite phone
systems. Many variables were evaluated and taken into account in this testing and the
results demonstrate that there are a number of statistically significant differences
between the two systems.

The most glaring distinction between the Iridium and Globalstar satellite phones noted
by the more than ten individuals testing the equipment was that of audio quality during
voice calls. It was universally observed and demonstrated in sampling after sampling
that the Globalstar system had a far superior audio quality compared to the Iridium
system. Even under ideal conditions, the Globalstar phone outperformed the Iridium in
the audio quality criteria. More importantly, the Iridium phone was rated as falling below
mission critical quality on anywhere from 10% to 35% of its calls in the two more
challenging test scenarios.

On the data side, both phones suffer from low data rates making web usage and data
downloads difficult. Nonetheless, when comparing the phones against each other, the
technicaladvantage that Globalstar has in data speed allowed this system to outperform
Iridium. Most importantly, Globalstar achieved a 100% success rate in more than 80
download attempts compared to 70% for Iridium.

All in all, Globalstar beat out Iridium for voice calls in most measurements, most
especially in audio quality. On the data side, Globalstar again outperforms Iridium on
the majority of criteria in this category.

Introduction to the Evaluation

Despite the well-publicized financial problems, past and present, of Iridium and
Globalstar, the fact is that both companies are operating their respective systems and
offering services to clients worldwide. For those potential customers looking into the
purchase of a satellite telephone, it is fair to ask, "which one will best suit my needs?"
There are many criteria involved in answering this question, such as planned usage,
handset cost, per-minute charges, quality of service, and each potential user will put
different priority on each of these criteria.

One of the characteristics of satellite telephones amenable to quantitative investigation
is that of "quality of service". The Satellite Communications Group of Frost & Sullivan,
an international market intelligence and growth consulting company, undertook an end
user comparison of the Iridium and Globalstar systems in order to determine their
relative merits in terms of "quality of service". Measurements taken, including call
completion, audio quality, call drop, and data rate, have been statistically evaluated
under numerous environments in order to provide an objective assessment of this
particular comparative criteria.

The study has been designed primarily to examine the call and data service quality of
these two satellite telephones. The methodology assumed a potential customer for a
handheld satellite telephone with the need for making voice calls and simple data
applications. The tests were designed around the idea of measuring, all else being
equal, which satellite telephone system would provide a superior call and data
capability.

Figure 1 provides an overview of the equipment and software used in the product
comparison.

F i g u r e 1

© 2002 Frost & Sullivan www.frost.com

Stacking Up the Voice Calls

In total, well over 1,200 minutes of airtime were accumulated on the two systems in a
series of more than 200 calls. A testing methodology was employed so as to ensure
that any deviations measured would be almost certainly due to the satellite phone
system. As such, all satellite phone calls were made to fixed lines within the
United States. None of the calls used for evaluation purposes were made to overseas
locations nor were calls made into cellular networks. The voice calls were also made
from two geographically different locations, Texas and California.

The primary measures taken for all voice calls were as follow:

- service availability
- call completion (does the call connect when dialed)
- audio quality (measured on a scale of 1 to 5)
- call duration (the duration of the call in minutes and seconds)
- call drop (does the call cut off unexpectedly)

The testing of the voice call capabilities of the two satellite telephone systems was
carried out in two distinct stages. First, both phones were tested side by side under
ideal conditions. This implies a completely clear sky free of any obstruction 10 degrees
above the horizon. Testing was also conducted far from any possible signal interference
that could be generated by airports, industrial zones, or any other such activities.

The results of the testing under ideal conditions showed that in most aspects, the
satellite telephones performed relatively similarly. Both experienced almost no service
outage and a first attempt call completion rate of 97% for Iridium and 100% for
Globalstar was recorded. The first attempt call completion is a measure of the
frequency a call was successfully made on the first attempt to dial a phone number.
The goal of all calls was to maintain the connection for at least 5 minutes and to extend
roughly one third of the calls to 12 minutes in duration. The longer call length was
desirable in order to maintain the call connection long enough to confirm that call
hand-offs from one satellite to another occurred as the satellites traveled across the sky.


Figure 2 summarizes the findings of voice calls made under ideal conditions.

F i g u r e 2

The Globalstar system had a very low drop rate, measured at 2.6%, under ideal
conditions. The Iridium system did not perform quite as well in this measure, recording
a drop rate of 18.4% under ideal conditions. The most dramatic difference between the
two systems was the assessment of audio quality. While audio quality of the call can
be a subjective measure, it was universally noted that the Globalstar audio quality was
significantly superior to that of Iridium. The effects of degradation in the audio signal and
a noticeable time lag gave the Iridium calls a universally lower scoring in this measure
in almost every instance. The effect was most noticeable on the call receiver end of the
conversation (i.e., the person receiving a call from someone speaking into a satellite
phone). Repeated comments related to the frequent loss of words or parts of words
most likely due to the loss of data packets. There was also a distinctive "Iridium drawl"
that gave the caller on the satellite phone a slurred voice. Under the ideal scenario, the
Iridium scored an average on 3.1 on a scale of 1 (unintelligible) to 5 (excellent) with
actual score ranging from a low of 1 to a high of 4.

Conversations over the Globalstar satellite telephone were regularly superior to Iridium
and could even be described as approaching that of a good quality cellular phone call.
In 23% of the instances under ideal conditions, the Globalstar audio quality could be
described as equivalent or better than a cell phone, while Iridium never achieved cell
phone quality in any of its ideal calls. This was defined by scoring 4.5 or better in audio
quality. Figure 3 shows the scores on audio quality for both phones in different calling
environments.


F i g u r e 3




The second stage of the research was to undertake extensive testing of the two satellite
telephone handsets in significantly more challenging environments. The two other
environments were urban and rural. In both cases, the same measures listed above
were made. In many ways, the testing took the two satellite telephones to their limits.
The methodology was devised so that each satellite telephone would be tested under
conditions of increasingly severe signal degradation. The urban testing measured the
effect of the proverbial "urban canyon" and the rural testing brought in elements such as
foliage cover and rugged landscapes.
The two systems performed as expected under difficult situations: the greater the
physical interference with the signal, the greater the rate of calls drops and
unobtainable service was noted. It was fairly remarkable that both phone systems were
in fact able to perform under circumstances that would not be recommended by the
service provider.

In the case of the urban environment, call completion rates were 77% for Iridium and
89% for Globalstar. This compared with 87% and 87% respectively in the rural
environment. (These figures represent call completion within 4 attempts; completion
rates on first attempt are provided in the charts that follow.) All in all, numerous
successful calls were made under situations with rather severe environments. Yet
again, the striking difference between the Iridium satellite telephone calls and that of
Globalstar was Iridium's distinctly poor audio quality. The audio quality scale was set
up so that any audio quality score of 2 or lower (on a scale of 1 to 5 as described
above) would be considered below the minimum needed for any mission critical
applications.

Of all calls that were completed (i.e. a call connection was established) in the urban
environment, Iridium's audio quality could be considered above mission critical for only
67% of the total completed calls compared to 100% for Globalstar. In the rural
environment, Iridium scored above mission critical for 85% of its completed calls
compared to 100% for Globalstar.

The other main factor was call drops. Here we noted similar percentages of call drops.
A rate of 70.4% in urban areas and 40.7% in rural areas for Iridium and 64.5% in urban
areas and 37.0% in rural areas for Globalstar.

Overall, it can be said that signal blockage is signal blockage, no matter which system.
If there was sufficient clear sky, both systems would be operable and the main
differentiator was audio quality. Under all types of conditions, Globalstar showed time
and time again a significant and measurable superiority over the Iridium system in this
aspect. Figures 4 and 5 summarize the findings for use of the two satellite phone
systems in rural and urban environments.

F i g u r e 4




F i g u r e 5




Figures 6 and 7 show the comparison of call connection rates and call drop rates for the
Iridium and Globalstar phones across calls made in all environments, indicating an
advantage for Globalstar in call connection and in call drop rates.

F i g u r e 6




F i g u r e 7




The Bits and Bytes of Data Calls

The typical application envisaged for this part of the investigation would be the use of the
Globalstar or Iridium handsets connected to a laptop computer for e-mail access and
simple data downloads. Often, these applications make use of an http-based Internet
browser. This posed a problem for our testing, since there is no simple methodology to
easily compare in a quantitative sense the browsing of web pages on the two satellite
telephone systems. Issues such as caching, spoofing, web page architecture, lost
packets, and busy servers make it difficult to set up an analysis such that any
potential problems can be isolated to the satellite system end of the network. If it is
unsure where the delays are introduced, then it is difficult to make a fair quantitative
assessment.

For this reason, the data service part of the experiment was divided into two segments.
First, in order to enable quantitative measures, the phones were tested using file
transfer protocol downloads (ftp) from a server located on a high-speed connection to the
Internet. Two files were chosen and multiple downloads were made in order to determine
the actual data rates.

The second part of the research was a qualitative assessment of web browsing on both
systems. These results are presented in the following section.


F i g u r e 8



In terms of data downloads, each file was downloaded 80 times which translates to
more than 20 MB downloaded over the combined systems. This was done equally over
the packet and dial-up modes offered by each service provider. Packet mode is where
Globalstar or Iridium provide access to the Internet through their respective gateways
and dial-up mode is where an independent Internet service provider (ISP) is used to
provide Internet access (essentially a dialup connection via satellite).

The potential compressibility of the files is important because Iridium employs a
proprietary data compression technology to improve its data rates when using its
packet service. The software automatically compresses files before they pass over the
satellite network. Of course, certain files are more amenable to compression than
others. Hence, the two files chosen for this research have very different potential
compression ratios and, as will be seen in the data below, this leads to a number of
important findings.

Figure 9 and Figure 10 provide a breakout of the data rates and download times for the
highly and minimally compressible files in both packet and dial-up scenarios.
Additionally, the percentage of successful downloads is given.

© 2002 Frost & Sullivan www.frost.com

F i g u r e 9






F i g u r e 1 0




It must be noted that compared to data rates most end users have grown accustomed
to in the business and home environments, the two systems are quite slow. This is not
surprising given that the two systems were both designed to primarily serve a market for
voice calls. Nonetheless, the research demonstrates that Iridium is only comparable to
Globalstar in the single category of downloading highly compressible files while using
their packet data service. This is due to Iridium's above mentioned use of data
compression technology. In every other measure, Globalstar is significantly superior to
Iridium.

While both systems are looking to improve data rates, any potential heavy data users
would find unacceptable the 2.28 to 7.62 Kbps data rates of either of the satellite
telephone systems. Yet, if an end user's requirement is the download of files or e-mails
limited to a few 100 kilobytes, then the side-by-side testing shows that the Globalstar
system offers a relatively superior data rate compared to the Iridium system under all
conditions. This is not unexpected, given the basic technical differences that are
inherent in the design of each system. It also indicates that while Iridium can (and does)
obtain up to 8 Kbps, the typical data rate will be much lower since most files used
today, especially those on web pages, are already compressed to an certain extent.
Iridium's compression technology will only be beneficial in a minority of instances.


Figures 11, 12, 13 & 14 provide a graphical illustration of the comparative data rates and
download times for the various scenarios studied.

F i g u r e 1 1



F i g u r e 1 2




F i g u r e 1 3


F i g u r e 1 4



 

F i g u r e 1 5



The Web and The Satellite Phone

As mentioned above, the second part of this phase of the research was an investigation
of applicability of satellite phone systems to web browsing. This was done simply by
accessing a number of different web sites and surfing through each site. A variety of
sites were chosen from "light" sites such as www.Google.com to heavy sites such as
"www.NBC.com." In addition, web pages in the United States, Japan and Australia were
browsed in order to seek a comparison between sites directly linked to the U.S.
backbone (to which both satellite telephone gateways are also connected) and those
remote from the U.S. backbone.

Both Globalstar and Iridium make ample warning to the end user that they should not
expect connections speeds similar to those we have grown accustomed to in our offices
and our homes. Even being fully armed with these warnings, web browsing is neither a
fun or pleasant experience when using satellite telephones. To speed the "surfing"
along, images and other multimedia downloads were turned off in the browser. Yet, it
was quickly realized that significant content is lost when this option is implemented.
And as web design advances in the future, it can be expected that there will be less and
less simple html text to view. As soon as the images where reinstated, the time to
download was greatly multiplied on both systems.

This said, how does Globalstar stack up to Iridium in this particular element of the
review? It is clear that the relatively greater data speed of the Globalstar system makes
web browsing possible, albeit at a rather slow rate. The much lower data rate for the
Iridium system makes web browsing a very unpleasant task. Add to this the relatively
high number of connection drops and stalled downloads, and web browsing becomes
a more or less impractical option with the Iridium system.

Fortunately, it is not expected that web browsing will be a major requirement for an end
user considering the purchase of a satellite telephone. Access to e-mail and ftp are
foreseen to be more typical data applications and as the results above indicate, the
Globalstar system is superior to Iridium in most measures within this research.

For more detailed information on the evaluation procedures utilized, the Satellite Communications
Group of Frost & Sullivan can be contacted through Juliette Salvati, Program Leader,
jsalvati@frost.com
Globalstar LP has funded this study, in order to provide an independent assessment of the Globalstar
and Iridium systems. Frost & Sullivan as an institution has no financial or material interest in
Globalstar LP or Iridium Satellite LLC.