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Feasibility of mobile satellite service in Alaska
Feasibility of mobile satellite service in Alaska
Alex Hills
Mobile satellite service, expected to be available in North America within a few years, appears to hold great potential for Alaska, particularly In areas away from population centres. This article examines several specific applications which are of interest to Alaska state agencies, and explores the implications of using the new service in these applications. An economic analysis is presented which compares the cost of mobile satellite service with the costs of alternative systems. In Alaska, as elsewhere, the Implementation decision must be based on comparisons of both the costs and the operating characteristics of competing systems. Alex Hills is Telecommunications Director at the University of Alaska Computer Network, 303 Tanana Drive. Fairbanks, Alaska 99775-5180, USA (Tel: 907-474 j665). This work was supported by the Alaska Department of Transportation and Public Facilities.
Dramatic technological developments are expected to make mobile satellite service (MSS) available in North America within a few years. This new service, which appears to have great potential for Alaska, will make it possible to communicate with radios which are installed in vehicles (mobiles) or radios that can be carried in backpacks (transportables) virtually anywhere on the continent. It is anticipated that the impact on communication services in rural and remote areas will be substantial. Communication satellites transmitting radiated power levels high enough to be usable by mobile and transportable stations will make mobile satellite service possible. Operation will be at 1.5-1.6 GHz. Direct communication links will be established between a satellite and mobiles, transportables, gateway earth stations, base earth stations, and a control earth station. Each base earth station will serve a dispatch console, and each gateway will provide connection to the public switched telephone network. The control earth station, an operations centre, will perform satellite and network control. Because of limited spectrum availability, 1.5-1.6 GHz will be used only for communication with mobile and transportable units. Ku-band (1402 GHz) will be used by base stations, gateways and the control station. The spacecraft will perform the necessary frequency translations. The new technology should perform best in nonurban areas, where there will be few path obstructions. In urban areas, where buildings can cause path blockage and multipath problems, performance will not be as good. Mobile satellite service is seen as a way to improve dramatically many communication services outside metropolitan areas, filling the gaps left by present terrestrial systems.
Candidate applications A number of very promising applications of MSS by Alaska’s state agencies have been identified. These can be divided into three categories: communication with vehicles on the highway system, communication with remote locations, and other communications.
0308-5961188/040369-10$3.00
0
1988 Butterworth
& Co (Publishers)
Ltd
369
Feasibility
of mobile
satellite srrvice
itt Aluska
Vehicles on the high way system The Department of Public Safety and the Department of Transportation and Public Facilities both have major needs for communication with vehicles operating on the highway system: the former to support the Alaska State Troopers and the latter to support highway construction and maintenance operations. In addition, ambulances also have a critical need for such communication. Two-way voice communication with a dispatcher is needed in a!! cases. In addition to the above vehicular needs, it would be helpful for project engineers on Trans-
portation and Public Facilities construction sites to have telephones. A two-way voice communication system is presently operated by the Department of Administration’s Division of Telecommunications Operations. This uses VHF radio, in conjunction with a microwave relay system, to provide highway coverage. Although most areas of the highway system presently have adequate coverage, significant gaps exist along a few of the highways. It is possible that MSS can be used to fill in some of the existing gaps in coverage. It is also possible that in the future MSS will provide a more cost-effective and/or reliable communications system than that presently being used. Remote locatiom The Department of Fish and Game and the Department of Natural Resources both have significant requirements for communication with field personnel in remote locations.
Fish and Game operates about 100 temporary camps each year. These are staffed by biologists and other field personnel, and are operated in connection with fish counting and other management and research activities. Fish and Game also operates a number of vessels in conjunction with the same activities. A!! of these require tvvo-way voice communication. The availability of telephone service would also be desirable in many situations. No present data communication requirement has been identified, but this may be needed in the future in connection with data entry and data access. Two-way voice communication services are presently provided to remote Fish and Game personnel through the use of a variety of systems, depending on individual circumstances. In truly remote areas, single sideband radio, which is often unreliable at high latitudes, is the only option. MSS, on the other hand, has the potential to be a single, reliable communication system for use by temporary camps, vessels, and research and management personnel located at permanent facilities. Within the Department of Natural Resources, the Division of Geological and Geophysical Surveys and the Division of Forestry both have the need for communication to remote locations. Geological and Geophysical Surveys operates remote seismic monitoring stations which transmit low-speed data. These must presently be located so that they can be connected by VHF to existing microwave facilities. MSS could provide this communication link, and with MSS the stations could be located virtually anywhere. The Division of Forestry has responsibility for firefighting over the southern part of Alaska. Firefighters very often work in remote locations, and they have the need for two-way voice communication with their dispatch centres. The need to communicate is obviously quite 370
TELECOMMUNICATIONS
POLICY
December
1988
Frusibility oJ’ mobile sutrllile senke
critical. Various systems are presently used, ances. MSS has the potential to substantially reliability of these communications.
depending improve
in Alusku
on circumstthe ease and
Other candidare applicarions Ships operated by the marine highway system, within the Department of Transportation and Public Facilities, have the need to communicate with shore facilities. Voice communication, presently provided through single sideband radio, is considered generally adequate, but there are some gaps in coverage. The marine highway system is interested in expanding its computer-based reservations systems to include computer terminals and personal computers located aboard the ships. These must be linked through a data communication circuit to a computer ashore. MSS appears to be an ideal \vay to provide the necessary data communication link. The Division of Emergency Services within the Department of Military and Veterans Affairs has a need for communication services when disasters occur. If other communication facilities are unavailable because of disaster conditions, MSS appears to provide an excellent way of establishing the vital links. Single sideband radio is presently used, but its reliability is not always adequate. Shadowing Even if Alaska is illuminated at adequate power levels by an MSS spacecraft, effective utilization of the spacecraft can be disrupted by terrain shadowing. This phenomenon will occur when terrain features block or disrupt the radio path between the spacecraft and the mobile or portable unit. Shadowing is a potentially serious problem for Alaska because, at northern latitudes, communication satellites in geosynchronous orbit appear at low elevation angles, that is, they appear close to the horizon. The shadowing problem has been studied carefully by means of a graphical technique which uses topographic maps. The results of this work, which have been reported elsewhere, indicate that shadowing is not likely to be a serious problem on most of the Alaska highway system or on the Alaska marine highway system.’
Economic analysis
‘A. Hills and D.C. Rogers, ‘A technique for assessing the severity of terrain shadowing in mobile satellite service’, /E/Z!!Transactions on Antennas and Propagation. Vol AP-4, No 4, April 1986, pp 601-603.
TELECOMMUNICATIONS
POLICY
The economic feasibility of mobile satellite service in Alaska can be evaluated by developing cost estimates for the use of MSS and the conventional systems it might replace. Such cost estimates are compared here for some of the candidate applications. Unfortunately, some of the costs of using MSS cannot be estimated accurately at this time. Where this is the case, a range of estimates is used. Where communication services are presently provided along the state’s highways, alon, 0 the coast and in remote areas, VHF or UHF systems supported by microwave or high frequency single sideband systems, are used. The costs of microwave-VHF (MW/VHF) and single sideband (SSB) systems will be compared to the cost of MSS. The costs of the three options are dependent on three variables: m = annual minutes of use = number of repeater sites needed u = number of terminal units in service
s
December
1988
371
Feasibility
of mobile
satellite service in Alaska
MSS will involve charges based on minutes of use, and MW/VHF requires the use of repeater sites. The cost of each of the three options will depend on the number of mobile and portable terminal units in service. It is assumed for purposes of comparison that each system includes a single base station and a number of mobile and/or portable terminal units. The annual cost of operating a MSS sytem is: A + Bm + Cu
where A =
annualized cost of a base station cost of one minute of satellite use C = annualized cost of a terminal unit B =
The annual cost of operating a MW/VHF system is: D + Es + FLI
where D =
annualized cost of base/dispatch facility annualized cost of a repeater site F = annualized cost of a terminal unit E =
The annual cost of operating a SSB system is: G + HL( where G = annualized cost of a base station H = annualized cost of a terminal unit Using these expressions, MWIVHF when:
it is clear that MSS will be less costly than
A + Bm + Cu < D + Es + Frc
Equivalently, (A-D)
+ Bm + (C-F)u
< Es
or
(A-D) y
+ “h$
+ (C-F)(u)<
E
s
where 7
is annual minutes of use per repeater
site and +
is number
of terminal units per repeater site. This form of the inequality is most convenient when considering mobile radio service along a highway. Similarly, MSS will be less costly than SSB when A + Bm + CLI < G + Hu
or Bm + (C-H)u Estimation
+ (A-G)
< 0
of Constants
Twelve companies applied to the Federal Communications Commission (FCC) in 1985 for permission to construct, launch and operate MSS satellites. The FCC subsequently announced its intention to license only
372
TELECOMMUNICATIONS
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1988
Feasibility of mobile satellire service in Alaska
one carrier and asked the applicants to form a consortium to provide MSS. In 1987, eight of the applicants formed the American Mobile Satellite Consortium (AMSC). As required by the FCC, a joint $ MWNHF amendment to the original applications was submitted on 1 February 39 700 Base/dispatch communications 116 160 19ss.* Repeater 2 000 Mobile unit The applications submitted by these companies have been examined 1 500 Portable unit in order to estimate the values of the constants A, B and C. All costs are SSB given in 1985 dollars. 8000 Base station The applications which addressed the question of base station cost 3 000 Mobile unit 2 500 contains cost estimates in the range of $50 000-$125 000.’ Since a base Transportable unit station installation will be a fixed earth station using Ku-band and some *Joint Amendment submitted by American terminal equipment, these cost estimates seem reasonable. For present Mobile Satellite Consortium, 1 February purposes, it will be assumed that the installed cost of a base station will 1988. be between $50 000 and $125 000, and probably about $75 000. 3See Application of North American Mobile Satellite, Inc, for Authority to Construct, Assuming that the real cost of capital is 4% (above inflation) and Launch and Operate a Land Mobile Satelequipment life is 10 years,4 and assuming that the annual maintenance lite Communication System, New York, cost is 3% of installed cost, the corresponding annualized cost (constant NY, 30 April 1985; and Application for Mobile Satellite Service, Vol I, Skylink A) will be between $7 664 and $19 161, and probably about $11 496. Corporation, Boulder, CO, 30 April 1985. MSS users will pay for satellite use based on the number of minutes ?So that all costs can be compared, used. The applicants who estimated the cost of satellite use suggested a one-time costs are converted to equivalent annual costs. This conversion is done in wide range of rates and a variety of rate structures.” For present constant 1985 dollars, assuming 1O-year purposes it will be assumed that the cost of satellite use will be based equipment life and a real interest rate of strictly on minutes of use. There is a good deal of uncertainty about 4%. ??ee Ref 2 and Ref 3 (re Shiplake what the rates will be but they will ultimately depend on the cost of Corporation). Also see the Application of building, launching and operating a satellite as well as demand for the Mobile Satellite Corporation for Authority service. They will also depend on what regulatory constraints are placed to Construct, Launch and Operate a Mobile Satellite System, Philadelphia, PA, on the satellite carrier. Here the cost per minute (constant B) will be 30 April 1985; Application of McCaw assumed to be in the range of 20 cents to $1.00. Space Technologies Inc, for Authority to The MSS satellite carrier will probably not manufacture terminal Construct and Operate a Mobile Satellite System, Bellevue, WA, 30 April 1985; equipment. Nevertheless, a number of applicants estimated the cost of Application of Wismer and Becker Conmobile and transportable stations. 6 Based on these estimates, it will be structing Engineers and Transit Comassumed here that costs for transportable and mobile units will be munications, Inc, for Authority to Construct and Operate a Domestic Mobile Satellite between $2 000 and $3 500. Thus, a unit’s annualized cost, including Service System, Pasadena, CA, 30 April maintenance (constant C), will range between $306 and $536. 1985; and Application of Global Land The costs of MW/VHF and SSB systems are well-known because such continued on page 374 Table costs
1. Comparative installed eC@pIIIent MWNHF and SSB systems.
of
Table 2. Estimated cost for microwave
repeater,
helicopter access, 6 channels. S
Tower (20 foot stub) 2 radios @ $11 000 2 antennas @ $2 500 Multiplex, comprising common equipment channel shelf channel card signalling termination shelf signalling termination card Erection and transportation 2 buildings (generator and communications) @$8000 Generator Solar plant Battery plant Battery charger Installation 12 man days @ $50/hr and $80 per diem VHF base station VHF base antenna
POLICY
December
2 500 22 000 5000 2 300 + 1 300khannel 1 500 300 600khannel 500 700khannel 15 000 16 8 2 10 2 5
000 000 500 000 500 760
2 500ichannel 300ichannel 116 160
Total
TELECOMMUNICATIONS
S
1988
373
Fusibility
of mobile sarellirr service in Alurka Table 3. Estimated 12 channels.
cost
for
microwave-VHF
base/dispatch
communications
facilities,
6
s
2 500 11000 2 500 2 300 f 1 300ichannel
Tower (20 foot stub) Radio Antenna Multiplex common equipment channel shelf channel card signalling term shelf signalling term card Erection Installation
1 500
300 600khannel 500 700khannel 5 000 800
16 man hours @ $50/hour 39 700
Total
systems are in widespread use. For comparison purposes, see Table 1 for installed equipment costs. The installed cost estimate for a MW/VHF repeater has been developed with the assistance of Alaska Division of Telecommunications Operations. Table 2 shows the components of the cost estimate. The ‘base/dispatch communications’ item includes the communications facilities needed at the dispatch location. The components of its cost estimate are given in Table 3. Using these installed costs, a real cost of capital of 4%, an equipment life of 10 years and an annual maintenance expense of 3% of installed cost, the values for constants D, E, Fl, F2, G, HI, H2 are those shown in Table 4.
Cost comparisons
continued from page 373 Mobile Satellite, Inc. for Authority to Construct and Operate a Land Mobile Satellite System, Washington, DC, 30 April 1985. Also see the Applications of Omninet Corporation for Authority to Construct, Launch and Operate Space Stations in the Land Mobile Satellite Service, Los Angeles, CA, 30 April 1985. %ee Refs 2.3 and 5 (re Omninet Corporation). See also Application of Hughes Communications Mobile Satellite Services, Inc, for a Land Mobile Satellite System, El Segundo, CA, 30 April 1985; and Application for MCCA American Satellite Service Corporation for Authority to Construct, Launch and Operate a Land Mobile Satellite System, Jackson, MI, 30 April 1985.
The cost of MSS can be compared with the cost of existing systems by using the expressions and cost estimates developed. This comparison is carried out in this section for four of the six candidate applications which have been identified. The four applications are: 0 0 0 0
Highway - voice Remote - voice Marine highway - voice Emergency services - voice
Cost comparisons are not performed for data applications because cost estimates for MSS data terminal equipment and transponder time are not generally available. Highway - voice
MSS will be less costly than MWNHF along a highway when Table 4. Summary
374
of constants
and estimated
service for mobile voice service
values.
Constant
Description
Estimated
A B C D E FI F2 G HI H*
Annualized cost of MSS base station Cost of one minute of MSS satellite use Annualized cost of MSS terminal unit Annualized cost of MWNHF base/dispatch facility Annualized cost of MWNHF repeater site Annualized cost of MWNHF mobile terminal unit Annualized cost of MWNHF portable terminal unit Annualized cost of SSB base station Annualized cost of SSB mobile terminal unit Annualized cost of SSB transportable terminal unit
11 496 0.2c-1 .oo 306-536 6 085 17806 306 229 1 226 459 383
TELECOMMUNICATIONS
POLICY
December
value $
1988
Feasibility
(A-D)+
+ BT
Recall
that
system,
7
s is the is annual
+ (C-F,):
snrellire
of microwave
repeater
of use per repeater
+ BT
+ (C-306)+
+ (C-306)+
in Alaskrr
in a given is
the
4,
< 17 806
If we are considering a section of highway repeaters, s = 10, and we have 541 + BT
sites
site, and $
number of mobile terminals units per repeater site. Substituting the values for A, D and Fi from Table 5411;
srrrice
< E
number minutes
of mobile
that requires
10 microwave
< 17 806
The value of B is in the range of $0.20 to $1.00. and the value of C is between $306 and $536. In the low-cost case, where B = $0.20 and C = $306. the inequality becomes 541 + 0.20111~ s
17 806
or F
< 86 325
This means that MSS will be less costly than MW/VHF if the use per repeater station is less than 86 325 minutes per year or 236 minutes per day. In the high-cost case, where B = $1.00 and C = $536. the inequality becomes 541 + % + 230+ If we assume repeater,
< 17 806
10 mobile
units on each section
of highway
served
by one
$- = 10, and
541 + $r + 2 300 < 17 806 or $r < 14 965 In this case, MSS will be less costly than MW/VHF only if the use per repeater station is less than 14 965 minutes per year or 41 minutes per day, a rather low figure. Thus, the economic attractiveness for mobile voice service along Alaska’s highways is quite dependent on the actual cost of transponder time and actual installed costs for mobile terminal units. Remote - voice, and emergency services - voice MSS will be cheaper voice communication Bm + (C-H& TELECOMMUNICATIONS
POLICY
December
1988
than SSB for remote when + (A-G)
and emergency
transportable
< 0 375
Frusibiliry
of mobile sarrllire service in Aluskrr
Substituting
the values for A, G and Hz from Table 1.
Bm + (C-353)0
+ 10 270 < 0
The value of B is in the range of $0.20 to $1.00 and the value of C is between $306 and $536. In the low-cost case, where B = $0.20 and C = $306, the inequality becomes 0.20m
- 77~ + 10 270 < 0
Even if we assume 100 transportable 0.20m
units in the field (U = loo), then
+ 2 570 < 0
and it is impossible for the inequality to be satisfied for positive values of m.
Since, even in the low-cost case the inequality is not satisfied, it appears that MSS will not be cheaper than SSB for remote transportable voice communication. Marine highway - voice
MSS will be cheaper than SSB for marine highway voice service when Bm + (C-H&
Substituting
+ (A-G)
< 0
the values for A, G and HI from Table 4,
Bm + (C-459)~
+ 10 270 < 0
The value of B is between $0.20 and $1.00, and the value of C is between $306 and $536. In the low-cost case, where B = $0.20 and C = $306, we have 0.20m
- 153~ + 10 270 < 0
Assuming 10 mobile units (U = lo), the inequality reduces to 0.20m
+ 8 740 < 0
It is clear that the inequality cannot be satisfied for positive values of m. Thus, for marine highway voice communication, MSS will not be cheaper than SSB. Of the four applications examined in this section, MSS is economically attractive for only one. For this application, mobile voice service along the highway, MSS will be less costly than the present MW/VHF service if the cost of transponder use and mobile terminal units are in the lower portions of the presently anticipated ranges. Estimate of MSS costs for four applications
In order to assist in assessing the cost of MSS, capital and operating cost estimates have been developed for the four applications just discussed. Three cost figures are given in Table 5: capital cost, operating cost Table 5. Capital, operating and annualized
376
cost estimates.
Scenario
Annual minutes of use (m)
No of terminal units (u)
Capital
Operating
Annualized
Highway - voice Remote - voice Marine highway - voice Emergency services - voice
110000 110000 110000 36000
20 200 10 10
130 630 102 102
58915 73 900 58 082 21 082
75 151 70 33
TELECOMMUNICATIONS
Cost estimates ($)
500 000 750 750
POLICY
December
004 572 750 750
1988
Feasibility
of mobile
satellite service in Alusko
and annualized cost. Capital cost is the initial cost of purchasing and installing necessary equipment; operating cost is the annual cost of operating and maintaining the system; annualized cost is the sum of annualized capital cost and annual operating cost. Capital cost is annualized assuming an equipment life of 10 years and a real interest rate of 4%. The cost estimates are based on the following assumptions: 0 0 0 0
The installed cost of a base station/dispatch facility is $75 000. Transponder use costs $0.50 per minute. The installed cost of a mobile or portable terminal unit is $2 775. Annual maintenance cost is 3% of installed equipment cost.
For each application, representative number of terminal units have been based on these values.
values for minutes of use and chosen. The cost estimates are
Conclusions A number of promising Alaskan applications of MSS have been identified. In these applications, MSS would provide more reliable and, in some cases, more convenient service than that which is presently
Table 6. Candidate
application
summary.
Candidate application
Existing system
Is MSS cheaper?
MSS advantages disadvantages
Highway - voice
microwaveNHF (some gaps exist)
depends on ultimate MSS costs
advantage:
disadvantage:
usually SSB
Remote - voice
no
advantage:
disadvantage: Remote - low-speed data
microwaveNHF
?
advantage:
disadvantage: advantage:
quick and easy setup more reliable than HFlSSB more costly than HFlSSB remote monitoring stations can be located anywhere within view of satellite (presently restricted to within VHF range of a microwave site) cost dependent on usage
SSB
fl0
Marine highway - data
none
?
advantage:
no existing system can handle this traffic MSS may be cheaper than installing any other new system
Emergency voice
SSB
no
advantage:
quick and easy to set up more reliable than HFISSB more costly than HFISSB
services -
disadvantage:
POLICY
no remote sites no related maintenance potential for high reliability incompatible with existing system cost dependent on usage
Marine highway - voice
disadvantage:
TELECOMMUNICATIONS
and
December
1988
more reliable than HFISSB more costly
Ftwsibiliry
oJ’ mobile
surrllire serricr
in Alasku
available. While there are no substantial technical barriers to the use of MSS in these applications, economic feasibility must be judged by comparing MSS costs with the costs of using existing systems to provide the same service. Shadowing is not expected to be a serious problem along Alaskan highways or along the Alaska marine highway. Table 6 lists each of the six candidate applications that have been identified. For each application, the advantages and disadvantages of using MSS are listed and, where service is presently being provided, the type of existing system is shown, as well as whether or not MSS will be cheaper. It has not been possible to do cost comparisons for two of the six applications, but of the remaining four there is only one application for which MSS may offer a cost advantage. This application is highway mobile voice service. The real appeal of MSS is not in the area of cost but in reliability and convenience, particularly in applications where HF/SSB is presently used. There is no present-day technology which will allow one to move into a remote area and establish a reliable voice communication link within just a few minutes. It is this capability that offers dramatic potential for remote area and emergency communications. MSS also promises the most reliable voice and data communications for the Alaska marine highway. For highway mobile voice service, MSS must compete with the present microwave VHF-based system. MSS would eliminate the need for mountaintop repeater sites, thus reducing maintenance expense and possibly improving reliability. On the other hand, if MSS were used on some portions of the highway system and MW/VHF on other portions, it would be advisable to use a mobile terminal unit capable of working with either system.
378
TELECOMMUNICATIONS
POLICY
December
1988
Alex Hills
Mobile satellite service, expected to be available in North America within a few years, appears to hold great potential for Alaska, particularly In areas away from population centres. This article examines several specific applications which are of interest to Alaska state agencies, and explores the implications of using the new service in these applications. An economic analysis is presented which compares the cost of mobile satellite service with the costs of alternative systems. In Alaska, as elsewhere, the Implementation decision must be based on comparisons of both the costs and the operating characteristics of competing systems. Alex Hills is Telecommunications Director at the University of Alaska Computer Network, 303 Tanana Drive. Fairbanks, Alaska 99775-5180, USA (Tel: 907-474 j665). This work was supported by the Alaska Department of Transportation and Public Facilities.
Dramatic technological developments are expected to make mobile satellite service (MSS) available in North America within a few years. This new service, which appears to have great potential for Alaska, will make it possible to communicate with radios which are installed in vehicles (mobiles) or radios that can be carried in backpacks (transportables) virtually anywhere on the continent. It is anticipated that the impact on communication services in rural and remote areas will be substantial. Communication satellites transmitting radiated power levels high enough to be usable by mobile and transportable stations will make mobile satellite service possible. Operation will be at 1.5-1.6 GHz. Direct communication links will be established between a satellite and mobiles, transportables, gateway earth stations, base earth stations, and a control earth station. Each base earth station will serve a dispatch console, and each gateway will provide connection to the public switched telephone network. The control earth station, an operations centre, will perform satellite and network control. Because of limited spectrum availability, 1.5-1.6 GHz will be used only for communication with mobile and transportable units. Ku-band (1402 GHz) will be used by base stations, gateways and the control station. The spacecraft will perform the necessary frequency translations. The new technology should perform best in nonurban areas, where there will be few path obstructions. In urban areas, where buildings can cause path blockage and multipath problems, performance will not be as good. Mobile satellite service is seen as a way to improve dramatically many communication services outside metropolitan areas, filling the gaps left by present terrestrial systems.
Candidate applications A number of very promising applications of MSS by Alaska’s state agencies have been identified. These can be divided into three categories: communication with vehicles on the highway system, communication with remote locations, and other communications.
0308-5961188/040369-10$3.00
0
1988 Butterworth
& Co (Publishers)
Ltd
369
Feasibility
of mobile
satellite srrvice
itt Aluska
Vehicles on the high way system The Department of Public Safety and the Department of Transportation and Public Facilities both have major needs for communication with vehicles operating on the highway system: the former to support the Alaska State Troopers and the latter to support highway construction and maintenance operations. In addition, ambulances also have a critical need for such communication. Two-way voice communication with a dispatcher is needed in a!! cases. In addition to the above vehicular needs, it would be helpful for project engineers on Trans-
portation and Public Facilities construction sites to have telephones. A two-way voice communication system is presently operated by the Department of Administration’s Division of Telecommunications Operations. This uses VHF radio, in conjunction with a microwave relay system, to provide highway coverage. Although most areas of the highway system presently have adequate coverage, significant gaps exist along a few of the highways. It is possible that MSS can be used to fill in some of the existing gaps in coverage. It is also possible that in the future MSS will provide a more cost-effective and/or reliable communications system than that presently being used. Remote locatiom The Department of Fish and Game and the Department of Natural Resources both have significant requirements for communication with field personnel in remote locations.
Fish and Game operates about 100 temporary camps each year. These are staffed by biologists and other field personnel, and are operated in connection with fish counting and other management and research activities. Fish and Game also operates a number of vessels in conjunction with the same activities. A!! of these require tvvo-way voice communication. The availability of telephone service would also be desirable in many situations. No present data communication requirement has been identified, but this may be needed in the future in connection with data entry and data access. Two-way voice communication services are presently provided to remote Fish and Game personnel through the use of a variety of systems, depending on individual circumstances. In truly remote areas, single sideband radio, which is often unreliable at high latitudes, is the only option. MSS, on the other hand, has the potential to be a single, reliable communication system for use by temporary camps, vessels, and research and management personnel located at permanent facilities. Within the Department of Natural Resources, the Division of Geological and Geophysical Surveys and the Division of Forestry both have the need for communication to remote locations. Geological and Geophysical Surveys operates remote seismic monitoring stations which transmit low-speed data. These must presently be located so that they can be connected by VHF to existing microwave facilities. MSS could provide this communication link, and with MSS the stations could be located virtually anywhere. The Division of Forestry has responsibility for firefighting over the southern part of Alaska. Firefighters very often work in remote locations, and they have the need for two-way voice communication with their dispatch centres. The need to communicate is obviously quite 370
TELECOMMUNICATIONS
POLICY
December
1988
Frusibility oJ’ mobile sutrllile senke
critical. Various systems are presently used, ances. MSS has the potential to substantially reliability of these communications.
depending improve
in Alusku
on circumstthe ease and
Other candidare applicarions Ships operated by the marine highway system, within the Department of Transportation and Public Facilities, have the need to communicate with shore facilities. Voice communication, presently provided through single sideband radio, is considered generally adequate, but there are some gaps in coverage. The marine highway system is interested in expanding its computer-based reservations systems to include computer terminals and personal computers located aboard the ships. These must be linked through a data communication circuit to a computer ashore. MSS appears to be an ideal \vay to provide the necessary data communication link. The Division of Emergency Services within the Department of Military and Veterans Affairs has a need for communication services when disasters occur. If other communication facilities are unavailable because of disaster conditions, MSS appears to provide an excellent way of establishing the vital links. Single sideband radio is presently used, but its reliability is not always adequate. Shadowing Even if Alaska is illuminated at adequate power levels by an MSS spacecraft, effective utilization of the spacecraft can be disrupted by terrain shadowing. This phenomenon will occur when terrain features block or disrupt the radio path between the spacecraft and the mobile or portable unit. Shadowing is a potentially serious problem for Alaska because, at northern latitudes, communication satellites in geosynchronous orbit appear at low elevation angles, that is, they appear close to the horizon. The shadowing problem has been studied carefully by means of a graphical technique which uses topographic maps. The results of this work, which have been reported elsewhere, indicate that shadowing is not likely to be a serious problem on most of the Alaska highway system or on the Alaska marine highway system.’
Economic analysis
‘A. Hills and D.C. Rogers, ‘A technique for assessing the severity of terrain shadowing in mobile satellite service’, /E/Z!!Transactions on Antennas and Propagation. Vol AP-4, No 4, April 1986, pp 601-603.
TELECOMMUNICATIONS
POLICY
The economic feasibility of mobile satellite service in Alaska can be evaluated by developing cost estimates for the use of MSS and the conventional systems it might replace. Such cost estimates are compared here for some of the candidate applications. Unfortunately, some of the costs of using MSS cannot be estimated accurately at this time. Where this is the case, a range of estimates is used. Where communication services are presently provided along the state’s highways, alon, 0 the coast and in remote areas, VHF or UHF systems supported by microwave or high frequency single sideband systems, are used. The costs of microwave-VHF (MW/VHF) and single sideband (SSB) systems will be compared to the cost of MSS. The costs of the three options are dependent on three variables: m = annual minutes of use = number of repeater sites needed u = number of terminal units in service
s
December
1988
371
Feasibility
of mobile
satellite service in Alaska
MSS will involve charges based on minutes of use, and MW/VHF requires the use of repeater sites. The cost of each of the three options will depend on the number of mobile and portable terminal units in service. It is assumed for purposes of comparison that each system includes a single base station and a number of mobile and/or portable terminal units. The annual cost of operating a MSS sytem is: A + Bm + Cu
where A =
annualized cost of a base station cost of one minute of satellite use C = annualized cost of a terminal unit B =
The annual cost of operating a MW/VHF system is: D + Es + FLI
where D =
annualized cost of base/dispatch facility annualized cost of a repeater site F = annualized cost of a terminal unit E =
The annual cost of operating a SSB system is: G + HL( where G = annualized cost of a base station H = annualized cost of a terminal unit Using these expressions, MWIVHF when:
it is clear that MSS will be less costly than
A + Bm + Cu < D + Es + Frc
Equivalently, (A-D)
+ Bm + (C-F)u
< Es
or
(A-D) y
+ “h$
+ (C-F)(u)<
E
s
where 7
is annual minutes of use per repeater
site and +
is number
of terminal units per repeater site. This form of the inequality is most convenient when considering mobile radio service along a highway. Similarly, MSS will be less costly than SSB when A + Bm + CLI < G + Hu
or Bm + (C-H)u Estimation
+ (A-G)
< 0
of Constants
Twelve companies applied to the Federal Communications Commission (FCC) in 1985 for permission to construct, launch and operate MSS satellites. The FCC subsequently announced its intention to license only
372
TELECOMMUNICATIONS
POLICY
December
1988
Feasibility of mobile satellire service in Alaska
one carrier and asked the applicants to form a consortium to provide MSS. In 1987, eight of the applicants formed the American Mobile Satellite Consortium (AMSC). As required by the FCC, a joint $ MWNHF amendment to the original applications was submitted on 1 February 39 700 Base/dispatch communications 116 160 19ss.* Repeater 2 000 Mobile unit The applications submitted by these companies have been examined 1 500 Portable unit in order to estimate the values of the constants A, B and C. All costs are SSB given in 1985 dollars. 8000 Base station The applications which addressed the question of base station cost 3 000 Mobile unit 2 500 contains cost estimates in the range of $50 000-$125 000.’ Since a base Transportable unit station installation will be a fixed earth station using Ku-band and some *Joint Amendment submitted by American terminal equipment, these cost estimates seem reasonable. For present Mobile Satellite Consortium, 1 February purposes, it will be assumed that the installed cost of a base station will 1988. be between $50 000 and $125 000, and probably about $75 000. 3See Application of North American Mobile Satellite, Inc, for Authority to Construct, Assuming that the real cost of capital is 4% (above inflation) and Launch and Operate a Land Mobile Satelequipment life is 10 years,4 and assuming that the annual maintenance lite Communication System, New York, cost is 3% of installed cost, the corresponding annualized cost (constant NY, 30 April 1985; and Application for Mobile Satellite Service, Vol I, Skylink A) will be between $7 664 and $19 161, and probably about $11 496. Corporation, Boulder, CO, 30 April 1985. MSS users will pay for satellite use based on the number of minutes ?So that all costs can be compared, used. The applicants who estimated the cost of satellite use suggested a one-time costs are converted to equivalent annual costs. This conversion is done in wide range of rates and a variety of rate structures.” For present constant 1985 dollars, assuming 1O-year purposes it will be assumed that the cost of satellite use will be based equipment life and a real interest rate of strictly on minutes of use. There is a good deal of uncertainty about 4%. ??ee Ref 2 and Ref 3 (re Shiplake what the rates will be but they will ultimately depend on the cost of Corporation). Also see the Application of building, launching and operating a satellite as well as demand for the Mobile Satellite Corporation for Authority service. They will also depend on what regulatory constraints are placed to Construct, Launch and Operate a Mobile Satellite System, Philadelphia, PA, on the satellite carrier. Here the cost per minute (constant B) will be 30 April 1985; Application of McCaw assumed to be in the range of 20 cents to $1.00. Space Technologies Inc, for Authority to The MSS satellite carrier will probably not manufacture terminal Construct and Operate a Mobile Satellite System, Bellevue, WA, 30 April 1985; equipment. Nevertheless, a number of applicants estimated the cost of Application of Wismer and Becker Conmobile and transportable stations. 6 Based on these estimates, it will be structing Engineers and Transit Comassumed here that costs for transportable and mobile units will be munications, Inc, for Authority to Construct and Operate a Domestic Mobile Satellite between $2 000 and $3 500. Thus, a unit’s annualized cost, including Service System, Pasadena, CA, 30 April maintenance (constant C), will range between $306 and $536. 1985; and Application of Global Land The costs of MW/VHF and SSB systems are well-known because such continued on page 374 Table costs
1. Comparative installed eC@pIIIent MWNHF and SSB systems.
of
Table 2. Estimated cost for microwave
repeater,
helicopter access, 6 channels. S
Tower (20 foot stub) 2 radios @ $11 000 2 antennas @ $2 500 Multiplex, comprising common equipment channel shelf channel card signalling termination shelf signalling termination card Erection and transportation 2 buildings (generator and communications) @$8000 Generator Solar plant Battery plant Battery charger Installation 12 man days @ $50/hr and $80 per diem VHF base station VHF base antenna
POLICY
December
2 500 22 000 5000 2 300 + 1 300khannel 1 500 300 600khannel 500 700khannel 15 000 16 8 2 10 2 5
000 000 500 000 500 760
2 500ichannel 300ichannel 116 160
Total
TELECOMMUNICATIONS
S
1988
373
Fusibility
of mobile sarellirr service in Alurka Table 3. Estimated 12 channels.
cost
for
microwave-VHF
base/dispatch
communications
facilities,
6
s
2 500 11000 2 500 2 300 f 1 300ichannel
Tower (20 foot stub) Radio Antenna Multiplex common equipment channel shelf channel card signalling term shelf signalling term card Erection Installation
1 500
300 600khannel 500 700khannel 5 000 800
16 man hours @ $50/hour 39 700
Total
systems are in widespread use. For comparison purposes, see Table 1 for installed equipment costs. The installed cost estimate for a MW/VHF repeater has been developed with the assistance of Alaska Division of Telecommunications Operations. Table 2 shows the components of the cost estimate. The ‘base/dispatch communications’ item includes the communications facilities needed at the dispatch location. The components of its cost estimate are given in Table 3. Using these installed costs, a real cost of capital of 4%, an equipment life of 10 years and an annual maintenance expense of 3% of installed cost, the values for constants D, E, Fl, F2, G, HI, H2 are those shown in Table 4.
Cost comparisons
continued from page 373 Mobile Satellite, Inc. for Authority to Construct and Operate a Land Mobile Satellite System, Washington, DC, 30 April 1985. Also see the Applications of Omninet Corporation for Authority to Construct, Launch and Operate Space Stations in the Land Mobile Satellite Service, Los Angeles, CA, 30 April 1985. %ee Refs 2.3 and 5 (re Omninet Corporation). See also Application of Hughes Communications Mobile Satellite Services, Inc, for a Land Mobile Satellite System, El Segundo, CA, 30 April 1985; and Application for MCCA American Satellite Service Corporation for Authority to Construct, Launch and Operate a Land Mobile Satellite System, Jackson, MI, 30 April 1985.
The cost of MSS can be compared with the cost of existing systems by using the expressions and cost estimates developed. This comparison is carried out in this section for four of the six candidate applications which have been identified. The four applications are: 0 0 0 0
Highway - voice Remote - voice Marine highway - voice Emergency services - voice
Cost comparisons are not performed for data applications because cost estimates for MSS data terminal equipment and transponder time are not generally available. Highway - voice
MSS will be less costly than MWNHF along a highway when Table 4. Summary
374
of constants
and estimated
service for mobile voice service
values.
Constant
Description
Estimated
A B C D E FI F2 G HI H*
Annualized cost of MSS base station Cost of one minute of MSS satellite use Annualized cost of MSS terminal unit Annualized cost of MWNHF base/dispatch facility Annualized cost of MWNHF repeater site Annualized cost of MWNHF mobile terminal unit Annualized cost of MWNHF portable terminal unit Annualized cost of SSB base station Annualized cost of SSB mobile terminal unit Annualized cost of SSB transportable terminal unit
11 496 0.2c-1 .oo 306-536 6 085 17806 306 229 1 226 459 383
TELECOMMUNICATIONS
POLICY
December
value $
1988
Feasibility
(A-D)+
+ BT
Recall
that
system,
7
s is the is annual
+ (C-F,):
snrellire
of microwave
repeater
of use per repeater
+ BT
+ (C-306)+
+ (C-306)+
in Alaskrr
in a given is
the
4,
< 17 806
If we are considering a section of highway repeaters, s = 10, and we have 541 + BT
sites
site, and $
number of mobile terminals units per repeater site. Substituting the values for A, D and Fi from Table 5411;
srrrice
< E
number minutes
of mobile
that requires
10 microwave
< 17 806
The value of B is in the range of $0.20 to $1.00. and the value of C is between $306 and $536. In the low-cost case, where B = $0.20 and C = $306. the inequality becomes 541 + 0.20111~ s
17 806
or F
< 86 325
This means that MSS will be less costly than MW/VHF if the use per repeater station is less than 86 325 minutes per year or 236 minutes per day. In the high-cost case, where B = $1.00 and C = $536. the inequality becomes 541 + % + 230+ If we assume repeater,
< 17 806
10 mobile
units on each section
of highway
served
by one
$- = 10, and
541 + $r + 2 300 < 17 806 or $r < 14 965 In this case, MSS will be less costly than MW/VHF only if the use per repeater station is less than 14 965 minutes per year or 41 minutes per day, a rather low figure. Thus, the economic attractiveness for mobile voice service along Alaska’s highways is quite dependent on the actual cost of transponder time and actual installed costs for mobile terminal units. Remote - voice, and emergency services - voice MSS will be cheaper voice communication Bm + (C-H& TELECOMMUNICATIONS
POLICY
December
1988
than SSB for remote when + (A-G)
and emergency
transportable
< 0 375
Frusibiliry
of mobile sarrllire service in Aluskrr
Substituting
the values for A, G and Hz from Table 1.
Bm + (C-353)0
+ 10 270 < 0
The value of B is in the range of $0.20 to $1.00 and the value of C is between $306 and $536. In the low-cost case, where B = $0.20 and C = $306, the inequality becomes 0.20m
- 77~ + 10 270 < 0
Even if we assume 100 transportable 0.20m
units in the field (U = loo), then
+ 2 570 < 0
and it is impossible for the inequality to be satisfied for positive values of m.
Since, even in the low-cost case the inequality is not satisfied, it appears that MSS will not be cheaper than SSB for remote transportable voice communication. Marine highway - voice
MSS will be cheaper than SSB for marine highway voice service when Bm + (C-H&
Substituting
+ (A-G)
< 0
the values for A, G and HI from Table 4,
Bm + (C-459)~
+ 10 270 < 0
The value of B is between $0.20 and $1.00, and the value of C is between $306 and $536. In the low-cost case, where B = $0.20 and C = $306, we have 0.20m
- 153~ + 10 270 < 0
Assuming 10 mobile units (U = lo), the inequality reduces to 0.20m
+ 8 740 < 0
It is clear that the inequality cannot be satisfied for positive values of m. Thus, for marine highway voice communication, MSS will not be cheaper than SSB. Of the four applications examined in this section, MSS is economically attractive for only one. For this application, mobile voice service along the highway, MSS will be less costly than the present MW/VHF service if the cost of transponder use and mobile terminal units are in the lower portions of the presently anticipated ranges. Estimate of MSS costs for four applications
In order to assist in assessing the cost of MSS, capital and operating cost estimates have been developed for the four applications just discussed. Three cost figures are given in Table 5: capital cost, operating cost Table 5. Capital, operating and annualized
376
cost estimates.
Scenario
Annual minutes of use (m)
No of terminal units (u)
Capital
Operating
Annualized
Highway - voice Remote - voice Marine highway - voice Emergency services - voice
110000 110000 110000 36000
20 200 10 10
130 630 102 102
58915 73 900 58 082 21 082
75 151 70 33
TELECOMMUNICATIONS
Cost estimates ($)
500 000 750 750
POLICY
December
004 572 750 750
1988
Feasibility
of mobile
satellite service in Alusko
and annualized cost. Capital cost is the initial cost of purchasing and installing necessary equipment; operating cost is the annual cost of operating and maintaining the system; annualized cost is the sum of annualized capital cost and annual operating cost. Capital cost is annualized assuming an equipment life of 10 years and a real interest rate of 4%. The cost estimates are based on the following assumptions: 0 0 0 0
The installed cost of a base station/dispatch facility is $75 000. Transponder use costs $0.50 per minute. The installed cost of a mobile or portable terminal unit is $2 775. Annual maintenance cost is 3% of installed equipment cost.
For each application, representative number of terminal units have been based on these values.
values for minutes of use and chosen. The cost estimates are
Conclusions A number of promising Alaskan applications of MSS have been identified. In these applications, MSS would provide more reliable and, in some cases, more convenient service than that which is presently
Table 6. Candidate
application
summary.
Candidate application
Existing system
Is MSS cheaper?
MSS advantages disadvantages
Highway - voice
microwaveNHF (some gaps exist)
depends on ultimate MSS costs
advantage:
disadvantage:
usually SSB
Remote - voice
no
advantage:
disadvantage: Remote - low-speed data
microwaveNHF
?
advantage:
disadvantage: advantage:
quick and easy setup more reliable than HFlSSB more costly than HFlSSB remote monitoring stations can be located anywhere within view of satellite (presently restricted to within VHF range of a microwave site) cost dependent on usage
SSB
fl0
Marine highway - data
none
?
advantage:
no existing system can handle this traffic MSS may be cheaper than installing any other new system
Emergency voice
SSB
no
advantage:
quick and easy to set up more reliable than HFISSB more costly than HFISSB
services -
disadvantage:
POLICY
no remote sites no related maintenance potential for high reliability incompatible with existing system cost dependent on usage
Marine highway - voice
disadvantage:
TELECOMMUNICATIONS
and
December
1988
more reliable than HFISSB more costly
Ftwsibiliry
oJ’ mobile
surrllire serricr
in Alasku
available. While there are no substantial technical barriers to the use of MSS in these applications, economic feasibility must be judged by comparing MSS costs with the costs of using existing systems to provide the same service. Shadowing is not expected to be a serious problem along Alaskan highways or along the Alaska marine highway. Table 6 lists each of the six candidate applications that have been identified. For each application, the advantages and disadvantages of using MSS are listed and, where service is presently being provided, the type of existing system is shown, as well as whether or not MSS will be cheaper. It has not been possible to do cost comparisons for two of the six applications, but of the remaining four there is only one application for which MSS may offer a cost advantage. This application is highway mobile voice service. The real appeal of MSS is not in the area of cost but in reliability and convenience, particularly in applications where HF/SSB is presently used. There is no present-day technology which will allow one to move into a remote area and establish a reliable voice communication link within just a few minutes. It is this capability that offers dramatic potential for remote area and emergency communications. MSS also promises the most reliable voice and data communications for the Alaska marine highway. For highway mobile voice service, MSS must compete with the present microwave VHF-based system. MSS would eliminate the need for mountaintop repeater sites, thus reducing maintenance expense and possibly improving reliability. On the other hand, if MSS were used on some portions of the highway system and MW/VHF on other portions, it would be advisable to use a mobile terminal unit capable of working with either system.
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December
1988