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XXI Meeting of COM/CITEL will be held in Washington, DC, USA from December 7 to 9, 2009 |
August 1995
The mandate of the Working Group of PCC.III on the use of VSATs in the Americas, coordinated by the Administration of Venezuela, is to "study the application of the use of VSATs in the Americas," as well as to concentrate and disseminate the information on the use of VSATs among the member countries of the CITEL. To that end, the Working Group paid particular attention to the documents prepared and submitted by the Members of the CITEL on that topic, in particular Document PTC.III-157/93.
The Working Group has considered the following documents on VSATs:
The following Delegates participated directly in the Working Group:
The documents submitted and studied by the member Administrations and the fluent exchange of opinions were of considerable value. Consequently, the Working Group was able to draft a general document that included all the papers submitted, with their respective summaries and modifications.
The Working Group, moreover, agreed on the importance of extending the scope of its work so as to keep abreast of technological innovations in the field of Small Aperture Terminals. Furthermore, the members of the Working Group concurred on the importance of continuing their analysis of the data submitted, together with other available research results on the use of VSATs.
The Working Group considered that the availability of a general document embodying the papers submitted by the Members of the CITEL on VSATs would orient its future efforts toward further study of the use of VSATs in the Americas, shifting the focus onto an analysis of trends in VSAT technology, particularly in regard to their impact on the development of rural telecommunications services and on the regulations governing VSATs.
The Working Group deemed it important to continue studying the use of VSATs in the Americas, as well as their impact on the development of telecommunications in isolated, rural areas.
The VSAT (Very Small Aperture Terminal) is an earth station in the Fixed (geostationary) Satellite Service used for a wide range of applications in the field of telecommunications, including interactive data and batch communications under different protocols, operation of networks with packet switching, voice services, data and image transmission, and wide area network operations. VSATs and related technology may be roughly divided into the following areas:
The use of VSAT terminals is suggested when it is necessary to transmit information to and from remote locations. Also, the addition of modulation techniques and low transmission power subsystems (the latter from the earth station) make them attractive for the use of space stations transmitting mainly to regions of higher traffic density.
This document deals mainly with spider network VSATs, because they are the most common. Section 8 includes some considerations on subjects exclusively related to USATs.
At the time this document was written, VSAT technology is in its third generation. The first generation began around 1980 and was mainly used for unidirectional transmissions, using the widened spectrum, of the C-band. The second generation, starting in 1983, added low speed bi-directional operation, using simple contention protocols, witnessed the introduction of Ku-band VSATs, and made the first steps towards network management and operation in general. The third generation, which began approximately in 1987, introduced a more efficient use of bandwidth, multiprotocol port systems defined by software, more modern network management and combined network operations (VSAT - earth station - LAN). USAT systems made their appearance approximately during the 1990s as a natural development of VSAT technology and a growing demand for highly integrated low cost systems.
PTC.III- 99/93 (Venezuela) presents more detailed information on the background, general architecture and operations of VSAT networks.
VSAT: Generic term applied to very small aperture earth stations. In practice it refers to earth stations carrying interactive data traffic.
Master Earth Station (Hub): Central node for the transmission, retransmission and channeling of a spider configuration VSAT network.
C-Band: Region of the radio spectrum of approximately 4 to 7 GHz.
Ku-Band: Region of the radio spectrum of approximately 12 to 14 GHz.
e.i.r.p. (Equivalent isotropically radiated power): A standardized measurement of the power generated from an antenna.
BPSK: Biphase phase shift keying, a modulation technique.
QPSK: Quaternary phase shift keying, a modulation technique.
Inroute: A carrier (channel) assigned to data transmission by satellite, including uplink to one or more VSAT stations and a downlink to the Master Earth Station (Hub); in other words, a channel from VSATs to the Hub.
Outroute: A carrier (channel) assigned to data transmission by satellite that includes the uplink from the Master Earth Station (Hub) and the downlink to a VSAT group; in other words, a channel from the Hub to the VSATs.
Contention Channel: A data channel with multiple source data for available bandwidth using a multiple access protocol.
1.2 Radiofrequency characteristics
VSATs operating on Ku-band transmit at 12-14 GHz, generally with narrow spectrum transmission channels and BPSK or QPSK modulation. Sometimes wide spectrum techniques are used in order to reduce the diameter of the antenna. Burst transmitters are generally of two watts or less. Ku-band VSATs may suffer attenuation due to humidity (rain fading), but there are practically no other problems with Ku-band signals. Currently, VSATs of less than a meter (USATs) use the Ku-band.
Currently, VSATs operating in the C-Band transmit at 4-7 GHz and generally use widened spectrum techniques to reduce the power required by the transmitter. Burst transmitters for C-Band VSATs generally have a power below 6 watts and it is also common to find 2 watt transmitters.
The diameter of antennas operating on C-band depends on many factors, among them interference coordination, climatic conditions, antenna beam projection on the earth's surface, etc. In general, the antennas are larger than those used for Ku-band, and the smallest ones are 2.4m in diameter. C-Band is relatively immune to heavy rain conditions, but interference due to ground microwaves is a subject which generally requires much attention for its coordination.
The VSAT spider networks require one or more higher-power carriers for the uplink from the Hub (outroute). Many other narrow band carriers (inroutes) are also assigned for the use of VSAT transmissions. Due to the fact that most VSAT transmitters operate in the burst mode with a contention protocol, many VSAT can share an inroute; the number of required inroutes is therefore significantly less than the number of VSATs in the network.
A VSAT network generally operates as a shared service network or an independent private network, giving a transparent protocol service between VSAT and Hub junction points. Thus, the only use of public networks may be the use of given ground services (such as data connection links between the Hub and network concentration nodes), using established protocols.
Occasionally, a VSAT network may be used to give services as an essential part of a public switched network (PSN). In this case it is particularly important to comply with current standards. There are two applications that require relatively urgent treatment:
ITU-R work group 4/3 also prepared a Draft Recommendation "VSAT Systems Connection to Private Networks and with the Public Integrated Services Digital Network". This Recommendation will be further studied by ITU-T study group 13.
3. Access alternatives for final users and interconnection requirements.
Final-user access to a VSAT network is made through interfaces at the following points:
Regardless of the location of the interface, there are two main aspects related to user access that call for standardization:
Standards for physical interfaces are generally established by the CCITT. The standards for main interfaces include V.11 (RS-422), V.24 (RS-232), V.35, and other LAN medium interface standards. Section 3.0 in document PTC.III-110/93 (Mexico) includes additional information about physical interfaces.
Although they are subject to standardization, the number of protocol or software interfaces currently on the market is practically endless. The VSAT networks currently in use can literally support hundreds of data communication protocols either through transparent framework bypass or the more efficient protocol tunnel.
Matters relating to protocol standardization are dealt with within the VSAT customer/vendor relationship, with the exception of those related to PSTN connections.
Section 9 of document PTC.III-99/93 (Venezuela) offers additional information on user interface protocols, generally called "access protocols". Protocols may be divided into many categories, such as:
VSAT network signal modulation aims at balancing three factors to obtain the highest data transmission speed with the lowest interference and use of band width.
The widened-spectrum and error-correcting techniques can be used to supply the necessary transmission speed without affecting e.i.r.p.
Documents PTC.III-105/93 (USA), PTC.III-106/93 and PTC.III-107/93 (USA) and section 3 of document PTC.III-25/93 (Argentina) offer additional information on modulation techniques.
Modulation techniques should be considered separately from channel-sharing techniques or access techniques. VSAT networks use or have used numerous multiple-access techniques to share available inroute bandwidth between VSATs. These techniques include FDMA, SCPC, CDMA, Aloha, and many variations on TDMA. Document PTC III-99/93 (Venezuela) offers a summary of these techniques (section 8 and Annex 1).
Of the two frequency bands most commonly used for VSAT systems (C- and Ku-bands), systems located in the Ku-band suffer from greater attenuation by rain/humidity (generally called "rain fading"). The seriousness of the problem depends on seasonal average rainfall in the region and the density of the rain. In tropical regions with heavy rain, the Ku-band may be inadequate although the problem may be solved by using larger diameters and adjustable power transmitters. It is also possible to use the bypass on request techniques, in places where they are available.
In zones where precipitation is not an important factor for the network's estimated availability (these calculations are not taken into consideration in this project), the Ku-band is an excellent choice, due to the low use of ground microwave systems.
In Canada, the United States and Mexico, the greatest part of the 12/14 GHz band does not have frequency allocations for ground services. This factor has facilitated the implementation of VSAT terminals in urban, semi-urban and rural zones that are coordination-free. The smaller diameters of the antennas required by the Ku-band, and an atmosphere with less interference, have favored the accelerated growth of VSAT services in the above countries. This growth, meanwhile, has created economies of scale based on the mass production of VSAT terminals. To protect the thousands of terminals that are already installed, and assure the proliferation of VSAT networks in the American continent, it is vital to maintain access to the exclusive spectrum for fixed satellite service in the Ku-band. In order to assure the use of VSATs in the 12-14 GHz bands, the future ITU conferences should not allocate additional services in this band.
VSATs in the C-band generally have two problems. The first is antenna diameter: C-band reception characteristics make antenna diameters less than 2.4 m impractical, considering the speed of data transmission currently used (512 Kb/s outroute). The second problem is spectrum interference, especially from ground microwave applications in urban areas. Section 5.1 of Document PTC.III-110/93 (Mexico) refers to specific problems of this nature.
It may be of interest to investigate the possibilities of multi-central systems utilizing a mixture of Ku- and C- band VSATs, thus benefiting from the resistance of each. Section 8 contains more information in this respect.
5.2 Available Capacity by Country
It is not currently possible to offer a wide database dealing with the availability,
coverage and utilization of the C and Ku spectrum. Documents PTC.III-99/93 (Venezuela) and
PTC.III-110/93 (Mexico) can be summarized as follows:
MEXICO:Current and projected availability of transponders
Morelos II: current Ku operation by VSATCOM (Mexico) and private networks.
SOLIDARIDAD I and II (1993-1994): Ku-band, 16 transponders of 54 MHz each; also C-band, with 12 transponders of 36 MHz each and 6 transponders of 72 MHz each.
LATIN AMERICA: Current and projected availability of transponders:
Mexico, Brazil and Argentina have satellites available. In addition, there is great transponder capacity in Intelsat and Panamsat.
Alpha Lyracom ORBX: new satellites for Latin America in 1994-1995.
There are plans for regional satellites for the Andean nations.
Telesat Canada, the owner of the Canadian Anik satellites, provides two standard services known as Anikom 200 and Anikom Access. Both are available in the C-band and the Ku-band, although VSATs in Canada are operated much more frequently in the Ku-band. The users of Anikom 200 utilize the "spider" topology with two shared Hubs located in Toronto and Montreal. Anikom Access is essentially a voice network in "mesh" topology, and utilizes Dama satellite access. There are also three companies that provide VSAT services to Canadian users over the Anik satellites: Canadian Satellite Communications (CANCOM), AT&T Tridom and Scientific-Atlanta.
5.3 Coordination of Interference
Document PTC.III-107/93 (USA) supplies further details about the collective license-granting agreements that have been developed for C- and Ku-band VSAT installations in the United States, as well as about the interference standards that must be complied with in order to efficiently prevent most interference problems. In particular, it covers the use of the 29-25 log theta curve (see CCIR Rec. 580 rev.2) for side lobe gain at angles from 1.5 to 7 degrees.
In Canada, the ground stations that comply with the Canadian government's VSAT definition have the advantage that the license approval process is carried out in a much shorter time period than under any other circumstances. The simplified license issuing process is possible since there are no requirements for the coordination of the Ku-band frequencies: neither Canada nor the United States operates ground installations in the 12/14 GHz bands. For this reason, interference is limited to the adjacent satellite networks, which can be coordinated for each transponder use by utilizing characteristics typical of ground stations, independent of the exact location of these ground stations within the satellite beam over the surface of the earth.
It is important to note that in spite of the existence of a large number of cases of interference from other services with VSAT operations (ground microwave, FM/TV analog satellites and SCPC, for example), the only known interference problem generated by VSATs to date has been inter-satellite interference (off-axis e.i.r.p.). This problem can be counteracted through the balance of the antenna diameter, the shape of the beam and the utilization of widened beam where necessary. In any case, coordinating the VSAT carriers with other C- and Ku-band services is necessary to avoid carrier interference problems.
Documents PTC.III-107/93 (USA) and PTC.III-105/93 (USA) offer a detailed study of inter-satellite interference problem and other matters that affect VSAT spectrum interference and interference coordination. It will also be necessary to refer to Section 7, where the regulatory aspects of interference coordination are described.
6.1 Signal levels
Signal levels are determined by adjusting the ground
station's e.i.r.p. Then the input and output levels of each of the ground station's
subsystems are adjusted. Finally, these adjustments are made on the transmitted and
received signal interfaces. These interfaces can be for voice, data, fax, video, etc.
Other transmission characteristics are determined by the technical parameters of the national satellites. VSAT link calculations are based on many factors, but the basic equation for ground stations is indicated below:
(C/N)= e.i.r.p. + (G/T) - K - B - LWhere:
e.i.r.p. = equivalent isotropically radiated power
(G/T) = ratio of system gain to system temperature
K = Boltzman's constant (-228.6 dB)
B = Bandwidth
L = Path attenuation; L = 20 log F(MHz) + 20 log D(Km) + 32.4 Ls
Ls = Additional path loss
The following is an illustration of a C-band installation in South America; the information is taken from document PTC.III-25/93 (Argentina).
Band: C
Latitude of the ground receiving station: 54S48
Longitude of the ground receiving station: 68W19
Longitude of the sub-satellite point: 71W
Reception frequency: 4.0 GHz
e.i.r.p. = 20 dBw
Receiving system temperature: 120 Kelvin
Receiving antenna gain: 33 dBi
Path attenuation: 195.2 dB
Receiver bandwidth: 500 Mhz
Carrier-noise ratio: 97.6 dB
6.2 Noise/interference performance
Earth stations operating in the C-band are
the stations most severely affected by interference caused by microwave systems operating
in the 4 and 6 GHz bands.
Potential users should carry out a prior analysis. For the theoretical analysis of this interference, the carrier/noise (C/I) ratio should be set to at least 25 dB.
6.3 Power requirements
Power requirements are based on the technical
characteristics of national satellites.
VENEZUELA: REGULATIONSIn Venezuela, use of the VSAT network is governed by the "Operating Regulations for Private Telecommunications Networks" of 3 October 1991. It covers all considerations relating to licenses and permits, including satellite use, interference, speed, radio spectrum, compatibility with public switched networks (PSNs), etc. The details of these regulations are given below.
Satellite use:
The space segment shall be administered by the regulatory body CONATEL (National Telecommunications Commission) in accordance with the guidelines contained in the International Telecommunication Union's Radio Regulations.
Companies that have signed agreements for satellite communications shall require the allocation of the satellite space requested by an operator on a non-discriminatory basis and in accordance with the principle of equal treatment.
Interference: The regulations establish that operators must use equipment that does not cause interference with other services on previously assigned frequencies, and they stipulate the measures to be taken by regulatory body in cases of proven interference.
Fees: Fees shall be set for all services provided by licensees with maximum and minimum values and for the use of the space segment. However, licensees may offer their users different conditions and rates in accordance with the particular features of the services they offer.
Use of the radio spectrum:
Compatibility: The systems and equipment installed shall be compatible with or provide a suitable interface for connection to the Basic Telecommunications System and to Venezuela's security and defense systems.
MEXICO: REGULATIONS
The Ministry of Communications and Transport (SCT), the governing body for communications systems, and Telecomunicaciones de México (TELECOMM), a decentralized agency in charge of the operation, use, and maintenance of Mexico's satellite systems, are responsible for creating and implementing communications policies and standards to allow the operation and coexistence of the different services and equipment that desire access to communications through the Morelos and Solidaridad I and II satellites. Thus, once the SCT has received a request for the installation and operation of a satellite service that is to function as either a private or public network, it proceeds to review, study, and issue a ruling on the request. If the request observes the requirements set down in Mexican legislation and therefore receives a favorable ruling, the system is authorized. For this purpose different legal documents are used, such as concessions, permits, and registrations; as a part of such authorizations, the satellite systems are required to obtain a standardization certificate from the SCT. Once these formalities have been completed, the recipient of the concession or permit is granted a period of 30 days to present the frequencies contracted with TELECOMM. This contracting of frequencies follows a procedure similar to that of the authorization. In addition, users of the authorized satellite network are required to effect satellite-access testing, in order to adjust operating levels and parameters.
Another important aspect for which the SCT and TELECOMM are responsible is the internal and external coordination of the levels of interference received and generated by the Mexican satellite system as well as by adjacent satellites, or between ground and microwave systems. For this reason, Mexico has an operating agreement with the United States for the 4-6 GHz band. A great number of both satellite and microwave systems operate in this band within the common border, while the 12-14 GHz band follows the guidelines established in the radiocommunications regulations of the International Telecommunications Union, as specified in appendixes 28 and 29.
USA: REGULATIONS
The regulation of installations and the granting of VSAT licenses in the USA is the responsibility of the Federal Communications Commission (FCC). A list of relevant publications appears at the end of this section.
About a decade ago, when satellite communications systems and applications were undergoing rapid growth in the United States, the government detected the need for special regulations to grant licenses and the operation of VSAT systems in order to maintain an efficient use of the radio spectrum and the geostationary orbit (GSO). It also became evident that it was necessary to accelerate the authorization procedures for VSAT networks with a large number of ground stations. The frequency bands allocated to the fixed satellite service (FSS) generally used in national satellite communications systems in Region 2 are to be found in the 4-7 GHz and 12-14 GHz bands.
To satisfy the great demand for fixed satellite services in these bands in the United States, the government designed an orbit plan with two degrees of separation between satellites in the corresponding segment of the GSO. Since VSAT systems use very small aperture terminals with relatively low antenna discrimination levels, it was necessary to set limits on transmission power flow densities and minimum antenna diameters. These limits, based on compatible operations with two-degree satellite orbit separations, gave rise to the VSAT standards for the US national satellite industry. To accelerate the granting of licenses for a large number of VSAT terminals, the accepted systems were granted "collective authorizations" covering all the VSATs in a network.
The following FCC publications deal with the granting of licenses and the operation of VSATs:
GUATEMALA: REGULATORY FRAMEWORK
First of all it should be pointed out that current Guatemalan legislation, through congressional decree, indicates that GUATEL -- the Guatemalan telecommunications company -- is the only company that can provide domestic and international telecommunications.
There is currently no specific regulatory framework in Guatemala regarding the treatment of VSAT-type terminals. However, a regulatory project is being carried out in GUATEL so that this type of technology can be used and supplied in such a manner that the possibilities for its complete utilization are increased, to the benefit of its users.
Some of the important aspects that have been included in the temporary operating contracts, and which are worthy of mention, include the fact that the VSAT service may have interconnection variants depending on the point of the Hub location and on whether it is national or international. Since this determines the location of the terminal antennas or A and B users, Guatemala has been divided into the following categories.
Domestic Hub: the service in which the master station is installed and operates in Guatemalan territory. This configuration includes the following cases:
International Hub: a service in which the master station is installed and operates outside of Guatemalan territory. This configuration includes the following cases:
INTEGRATION OF VIDEO AND VOICE
[Also see document PTC.III-110/93 (Mexico)]
It is probable that we will see the integration of video into low-cost, small-antenna VSATs, based on the beginning operation of direct broadcasting satellites (DBS). The integration of voice (packet spider switched networks, and direct mesh networks) will increase in importance to the degree that more efficient and capable systems are put into place. And voice service is of special interest in remote and rural zones. Another future possibility is the inclusion of integrated services digital networks (ISDNs) into private commercial networks.
MULTI-CENTRAL NETWORKS
In the near future it is possible that we will see the introduction of software-integrated multi-central networks that will permit the general switching of packets between different outroute VSATs. Thus we would have the possibility of much wider networks and the possibility of networks that mix C- and Ku-band VSATs, or VSATs that utilize distinct speeds and outroute encoding methods.
INTEGRATION OF NETWORK MANAGEMENT
The subsequent integration of VSAT NMS (Network Management Systems) with NMS platforms such as Netview, UNMA and others, is expected by the mid-1990s.
USAT NETWORKS
[Also see document PTC.III-106/93 (USA)]
The diffusion of VSAT networks in fixed-satellite service (FSS) with small-antenna ground stations at distant locations -- such as the terraces of office buildings, hotels, shopping centers and other useful locations -- has stimulated the development of antennas that are even smaller than VSATs, generally with an effective aperture of less than 1 m. In general, they are known as ultra small aperture terminals (USATs). The antenna's discrimination naturally deteriorates as its size decreases.
As a result, in an environment of geostationary orbit satellites (GOS) that are separated by 1, 2 or 3 degrees in orbit, it is not possible to operate with carriers that use the same frequency in adjacent satellite systems. The reason is that the main USAT beam affects the receiving beam of the adjacent satellite. For example, in the Ku-band (12-14 GHz), a center-fed parabolic antenna and a diameter of 1 m (ratio of diameter to length of wave: D/l =50) would have an average main beam width (HMBW) of approximately 1.4 to 2.3 degrees. An antenna with a D/l of 50 (0.8 m of diameter) would have an HMBW of approximately 1.7 to 2.9 degrees. The USAT antenna is generally designed as a horizontal or truncated ellipsoid, restructuring the main beam to reduce interference in the direction of adjacent satellites. This is normally adjusted with an equatorial mount to preserve alignment during aiming.
However, the resulting increase in interference between satellite systems that share the same frequency and coverage in the GSO may have a negative effect on the communicating capacity of the FSS systems. There should be more in-depth study of the topic. This document investigates potential problems in the use of USATs in the current FSS environment, and offers some suggestions for mitigating potential interference by decentralizing the carrier frequencies and utilizing widened spectrum modulation techniques. Care must be taken in understanding and handling the relationship among the following three factors in order to minimize interference:
VSAT and USAT characteristics (20 GHz-30 GHz)
In September 1993, the United States launched the advanced communication technology satellite (ACTS), which began to function in December of the same year.
The main purpose of the ACTS is to demonstrate the capacity of advanced technology in order to permit the use of fixed-satellite service (FSS) bands of 20 GHz (approximately) for space-to-earth telecommunications links, and 30 GHz (approximately) for earth-to-space links. The use of these bands will be beneficial since it will introduce new services, increase the capacity of satellite systems, and allow efficient use of the spectrum and the geostationary orbit. Document PCC.III 23/94 includes a more complete technical description of the satellite, as well as of VSAT and USAT ground equipment.
An Example of an International USAT Network
The proposed international system of interconnected networks in mesh with ultra small aperture terminals (VSATs of less than 1 meter) was described by an administration (see Doc. PCC.III-22/94). The system would operate in the Ka band frequencies allocated to fixed-satellite service (FSS) (27.5-30.0 GHz for uplinks and 17.7-20.2 GHz for downlinks), using satellites in the geostationary satellite orbit (GSO). This system would offer direct access on demand to completely digital bi-directional and interactive circuits, that would fluctuate from 16 Kb/s for telephones up to 384 Kb/s and 1,544 Mb/s (T1) for data, video and videoconferencing.
The greatest majority of USAT terminals would employ cheap antennas with a diameter of 66 centimeters, together with transmitters of 0.1 W, whose output would increase in proportion to rain attenuation, up to a maximum of 0.5 W. This size antenna was chosen in order to allow orbital spacing of 2 degrees and facilitate the installation of USATs at residential and commercial locations.
Worldwide USAT coverage would be carried out by means of a total of 17 geostationary satellites (GSO), pencilbeamed to space in two phases between 1997 and 2003. Conglomerates of four satellites would be located in each of the nominal orbital positions in order to provide service to all the continents and islands territories, with an additional satellite that would establish one-jump links between Asia and North America. These conglomerates would be connected by wide-band inter-satellite links, operating at 60 GHz, in order to achieve global connectivity. Each satellite would have up to 48 point beams (24 beams geographically separated at each polarization) connected to repeaters of 20 W and 120 @, which would re-utilize each frequency 12 times.
The 9 satellites in the phase I system (two satellites per conglomerate) would offer 100,000 simultaneous simplex circuits of 384 Kb/s, equivalent to more than 2 million telephone calls, by means of 66-cm diameter USAT terminals. The 17-satellite system in phase 2 would offer twice these capacities.
PTC.III-107/93 V-SAT Performance Standards Adopted by the U.S. (USA)
PTC.III-105/93 VSAT Intersatellite Interference Considerations (USA)
PTC.III-106/93 Interference Considerations of Ultra-Small Earth Stations Used in the Fixed
Satellite Service (USA)
PTC.III-99/93 VSAT networks: Mobile Services Coordination (Venezuela)
PTC.III-110/93 Comments on VSAT Systems (Mexico)
PTC.III-25/93 Use of VSAT Terminals Presented by Argentina (Argentina)
PTC.III-131/95 Response to the Report on the Utilization of VSAT-type Terminals in
Guatemala
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