Chapter 5: Satellite Networks
5.1: Ku-band and Ka-band
While many rural areas of Canada fall along major highways and major ![Figure 37: Anik F2 [45]](figures/37.jpg)
Internet backbones, the truth is that some communities live in remote areas well off the beaten path. Sparsely populated areas more than 100 or 200 kilometres from the nearest broadband pipeline likely have little chance of being connected by fibre or wireless backhaul. Fortunately one form of broadband Internet service covers all of Canada, from the largest cities to the wildest forests. Satellite Internet service has gone through a rebirth in the last couple of years with the deployment of new technologies, and is now more affordable and available than ever before.
Geosynchronous communications satellites are like giant broadcast repeaters in the sky. A single satellite costs hundreds of millions of dollars [8] and can broadcast television, radio, Internet, and other services to an area the size of a continent from about 35,000km above the Earth. Satellites can operate in one of several microwave frequency bands, two of which are used by the satellites that provide broadband Internet access: Ka-band and Ku-band. The Ka-band is the name given to frequencies between 20 and 30 GHz, while the Ku-band ranges from 11 to 14 GHz [72: 111]. The 2004 launch of Anik F2, one of the largest and most powerful communications satellites ever built, was the first time the Ka-band was commercially utilized [8].
To receive signals from a satellite, a parabolic microwave antenna called a satellite dish is installed outdoors and pointed toward the southern sky. A 
clear view is needed; trees or heavy precipitation will interrupt the signal. The process of aligning a satellite dish can sometimes be difficult, so professional installers are often needed. While satellite television dishes are receive-only and can be installed by anyone, most satellite Internet dishes also transmit data. In that case, Industry Canada and the FCC require licensed installers to install these satellite transmitters because an improper installation could cause interference on other satellites. The satellite dishes used for Internet service are often a metre across, about twice as large as your typical satellite television dish. A satellite service provider will operate a 
teleport or uplink facility where a very large satellite dish, usually a few metres across, is used to send all data up to the satellite. In the case of satellite Internet providers, this teleport will have a very high capacity Internet pipeline connection and plenty of computers and other hardware for managing the subscribers. When a subscriber requests data from some Internet server, the request will be transmitted by the dish up to the satellite, and the satellite will relay it back down to the teleport. From there, it will go out onto the Internet through the pipeline, and the requested data will come back to the teleport. The data is transmitted up to the satellite, and the satellite will broadcast it back down to the subscriber's dish.
Internet service has been available by satellite in Canada for about ten years. The first consumer technology was called terrestrial return because it used the satellite connection to receive data and a dial-up connection to send data. One provider of this service was Bell ExpressVu, which operated their DirecPC Internet service on their “Nimiq” Ku-band satellite. Using a $300 PCI or USB modem connected to an ExpressVu TV dish, a subscriber could pay about $80 a month for a downlink speed of up to 1 Mbps. The dial-up uplink connection, however, was limited to a maximum speed of 56 Kbps, so things like videoconferencing were not possible. By the time ExpressVu's DirecPC service was terminated in June 2005 [40], two-way satellite Internet services had already made significant inroads into the market.
In early 2002, DirecWay satellite Internet service was introduced in Canada by LinCsat Communications Inc. and is now operated by Xplornet. Using the 
Ku-band Galaxy 11 satellite [32], DirecWay reaches every corner of Canada and doesn't require a dial-up connection for the uplink. DirecWay requires the professional installation of a 1-metre-wide two-way satellite dish, which needs to be very precisely aligned. Indoors, a satellite modem that resembles a DSL or cable modem is installed and connected to the computer by a cat-5 Ethernet cable. The hardware plus installation costs about $1000. DirecWay can operate at up to 2 Mbps for downloads and 1 Mbps for uploads [68]. Unfortunately bandwidth on a satellite is limited, so these kinds of speeds come with a premium monthly fee. Packages start at $80 a month for 700 Kbps down and 128 Kbps up, which is slow compared to DSL or cable but is a significant improvement over dial-up. A package with speeds of 1.5 Mbps down and 300 Kbps up, which is comparable to DSL or cable, comes with a monthly bill of $150. To increase the download speed to 2.0 Mbps and the upload speed to 1.0 Mbps, the monthly bill jumps to nearly $500 [68]. Performance of a DirecWay system can be unpredictable, especially when it's windy or raining outdoors, as the dish is extremely sensitive to misalignment. While throughput can be adequate, latency due to the satellite's altitude often exceeds 1 second. This renders bidirectional synchronous communication like videoconferencing, VoIP and virtual private networking useless.
In the Spring of 2005, DirecWay gained a competitor when Telesat's Ka-band broadband Internet service was introduced on the Anik F2 satellite. Telesat has a small network of service providers including Xplornet, Infosat, ![Figure 41: Ka-band Dish [42]](figures/41.jpg)
NetKaster, NorthernTel, and Télébec, with Xplornet being the only provider that serves the entire country [6]. In the United States, WildBlue is the sole service provider [7]. This new Ka-band service is capable of higher throughput for a lower price thanks to advantages introduced by higher frequencies and wider bandwidths of the Ka-band. The hardware setup for Ka-band Internet service is similar to DirecWay. The dish is about 30% smaller and can transmit and receive data to and from the satellite. It is connected to a satellite modem indoors, which is connected to a computer by a cat-5 Ethernet cable. Two interesting differences give this Ka-band service a performance advantage over DirecWay. DirecWay's Galaxy 11 satellite has a single spot beam covering all of North America, while Anik F2 has 45 spot beams divided into six groups. These spot beams allow the satellite to dynamically shift unused bandwidth from one spot beam to another when demand is high in one geographic area. Spot beams allow frequencies to be reused in each of the six groups, giving the satellite a much improved capacity over ![Figure 42: Ka-band Modem [42]](figures/42.jpg)
DirecWay's Galaxy 11 Ku-band satellite [7]. The other advantage is that while DirecWay uses a modem technology developed exclusively for satellite communication, the modems used with the Ka-band service are based on the industry standard DOCSIS cable modem standard. Because DOCSIS technology is so widely used, it allows for significantly less expensive customer premises equipment [7].
Internet speeds through this service are comparable to DirecWay, but pricing is significantly lower. Through Xplornet, hardware can cost as low as $600 and speeds can be as high as 2.0 Mbps down and 500 Kbps up (for $180/mo). The cheapest package gives you a throughput of 512 Kbps down and 128 Kbps up for $55 a month. For speeds comparable to DSL or cable (1.5 Mbps down, 300 Kbps up), the monthly bill is $135 [68]. Performance of this Ka-band system is reported to be better than DirecWay, though this hasn't been verified. Likely due to the spot beam technology and the high-performing DOCSIS modem standard, latency is slightly better and the service is more reliable. Latency remains significant, however, with a theoretical minimum of about half a second for a request and reply. Xplornet does, however, claim that the latency is low enough that VoIP is possible.
DSL, cable, WiFi mesh, 3G cellular, Canopy and WiMAX will all provide a higher quality of service for less money, so consumer-grade satellite systems should usually be a last resort. With Ka-band service costing less and performing better than DirecWay, it is clearly the superior technology. It will likely continue to gain a larger slice of the satellite Internet market over the next couple of years. When wired or wireless broadband Internet access isn't feasible in an area due to geography or economics, satellite broadband is an excellent alternative. With wireless technologies like WiMAX posed to bring broadband Internet service to many rural areas over the next couple of years, however, Canadians living in rural but not remote areas may soon not have to resort to satellite-based Internet access.
© Jake Cormier, 2006 [jake (at) stormcloudstudios.com]
Completed as a partial requirement for the degree of Bachelor of Science (specialized)
Department of Computer Science :: Algoma University College :: Sault Ste. Marie, Ontario :: Spring 2006