by Peter J. Brown

Several companies are making substantial contributions in terms of enhancing the performance of satellite networks. Greater reliability and efficiency means getting more bang for the buck out of a typical satellite transmission, while making satellite services more affordable helps to attract lots of new customers as well.

Three years ago or so, for example, the typical null packet in a digital satellite transmission was viewed by the satellite industry as something that was simply along for the ride. Today, thanks to advanced techniques available, allowing null packets to slip by undetected or transmitting any signal that is not crammed full of content is unacceptable.

The companies mentioned in this article deserve lots of credit for their creativity, and their stubborn pursuit of opportunities where, in many cases, none existed previously. They have crafted new sets of tools for their clients, and they have opened new doors by transforming many a hypothesis into a viable, user-friendly solution.

With this planet increasingly crisscrossed by fiber optic cables and by terrestrial wireless networks, many of the companies identified here have pursued earthbound markets too. And in many instances, you will encounter these companies not as competitors, but working together in pairs or threesomes, offering layers of products that can produce dazzling results for satellite network providers and users alike.

Focusing On Open Architecture

Jim Olson, president and CEO of Skystream Corp. in Mountain View, CA, believes his company has made a major contribution not only to the effort to help ease broadcasters through the sometime-difficult transition to an open architecture-based environment, but also to the establishment of DVB Simulcrypt as a worldwide standard. Both Skystream’s new DBN-26 Media Router, and its predecessor, the DBN-25, feature null packet optimization (NPO) software that injects data, including IP content, into the MPEG 2 stream after detecting and replacing null packets.

"We’re the enabler. With our DBN-26 Media Router, a broadcaster can pick whatever conditional access or compression system is appropriate, and our technology can make them work together. We believe that a unifying platform is something that is always needed. And that’s what we have created," says Olson. "In a business where the stratification of content is ongoing, we offer two value-add contributions in a single solution. The DBN-26 can add data seamlessly to whatever digital transport is used, scramble some or all of the content, and do so while offering complete interoperability at the same time."

A year ago, for example, Skystream took part in a HDTV-related trial with PBS and Intel Corp.-an investor in Skystream-where empty null packets flowing onto Gateway PCs were filled with IP content by the DBN-26. Olson indicates that while this particular demonstration did not entail a satellite feed, null packets make up to anywhere between 2 to 10 percent of a typical DVB satellite feed.

"NPO finds empty bandwidth, and fills it with data opportunistically. In a typical one-hour HDTV transmission, for example, we can fill 2 percent of the 19.4 Mbps HD feed with the equivalent of approximately 15,000 Web pages. By the way, that 2 percent is on the lower end of the empty packet scale," Olson adds. "On some satellites using the DVB standard, the presence of null packets can run as high as 30 percent, and yet with statistical multiplexing in place, the number has often been closer to well below 2 percent."

According to Olson, the DBN-26 also allows the operator to run multiple versions of conditional access (CA), so long as the CA vendor in question provides a DVB-Simulcrypt compliant CA interface.

"This allows a company like Echostar Communications Corp., for example, to purchase the lowest cost, highest performance conditional access and encoding equipment, and interface them with the DBN-26. In effect, we can tie companies together. In this instance, I am referring to Nagra and Divicom," Olson says. "We formed a relationship with Nagra, for example, and helped to move them into DVB-Simulcrypt."

Skystream is building powerful partnerships with other companies like Scientific-Atlanta Inc., International Datacasting Corp., Philips Electronics, NDS Ltd., Tiernan Communications and Irdeto, the California arm of the Netherlands-based Mindport.

At the State University of New York (SUNY) in Albany, Skystream’s DBN-26 has been installed at Sunysat, the satellite services arm of The New York Network, by Miralite Communications, which is serving as the systems integrator. As part of a near video-on-demand (NVOD) pilot test involving 11 sites, the DBN-26 Media Router is allowing Sunysat engineers to combine Nagra’s conditional access technology for the first time ever with General Instrument Corp.’s Magnitude DVB encoder. Harmonic Data System’s Cyberstream Sat1 MPEG 2 PC/PCI receiver cards are deployed at the desktop.

Sunysat recently acquired a full 54 MHz Ku-band transponder aboard GE 5, which has been split in half to allow for three analog channels and three digital channels, although this number should soon double, according to William F. Snyder, executive director of The New York Network/Sunysat. The NVOD capability allows users to access a database of SUNY programming, preview educational content on Quicktime, and then download the appropriate video file into a Pentium 2 PC.

"The change is significant, and we are growing with it. We are trying to determine what speed we will be running at, so for now we are testing at 50 kbps at the low end, up to 400 to 500 kbps. We are running IP multicast with Skystream’s NPO through Nagra’s conditional access system," says Jack Hanna, Sunysat’s chief engineer.

"Skystream’s Streamnet and Streamview software modules run with the DBN-26 Media Router and allow the system to efficiently and dynamically adapt to changes in bandwidth. This ensures the most optimal use of the transmission spectrum," Olson says. "Streamnet automatically controls the TCP/IP and UDP/IP data flows, while Streamview provides a real time view of each program’s instantaneous bandwidth utilization."

Skystream has an additional software module known as Jetstream, which manages the aggregation and scheduling of content, while providing an integrated electronic programming guide (EPG) that is sent directly to users, according to Olson. With the acquisition of Ontario-based Varuna Software Inc. in late September 1999, Skystream is adding considerable depth to its already impressive software-related capabilities. In December, Ibeam Broadcasting Corp. announced that it had selected Skystream’s DBN-26, and Lucent Digital Video announced that it would team up with Skystream.

Tapping Into The Cyberstream

Atlanta-based CNN Newsource provides 17 daily weekday news feeds and 12 daily weekend news feeds to more than 550 North American network affiliates and independent TV stations. In addition, there is a low-resolution browse system that enables users at the receive sites to scan material available from Newsource-On-Demand. This year, CNN Newsource selected San Diego-based Harmonic Data Systems’ (HDS) Cyberstream Data Gateway TRX100 and Cyberstream SAT1 PC/PCI satellite receiver cards in order to make the transition to a new digital solution. Kencast’s Fazzt is also used here to enhance the data broadcasting process.

"We are using IP multicast for the first time and it is a big plus," says Todd Fantz, supervising director of technology for CNN Headline News. "We are using the Cyberstream for file distribution. There have been no failures, and set-up time for the system is reduced dramatically. The Cyberstream card can handle low-, mid- and high-resolution traffic. It can handle a full transport stream if necessary.

"The Cyberstream Gateway represents an investment, but the cost of the cards is non-existent. It is easily scaled up because it is very cost-efficient to add new clients," Fantz adds. "We are using a fraction of what the system is capable of."

Not all the receiving stations run IP to the desktop, and working with so many stations where everyone is a little different in terms of LAN access and other capabilities requires a bit of fine-tuning, according to Fantz. In addition, the sheer scope of the CNN Newsource daily operation does not allow for retransmission in the event of a misfire.

"There is no mechanism which allows an affiliate to request missing packets, so to minimize the chances that someone might drop one, we run 25 percent error correction on top of it. Because of the volume, we are not in any position to retransmit the whole feed," Fantz says.

Before CNN Newsource activated Cyberstream, a hodge-podge of equipment not designed to provide data broadcasting was in place, according to Fantz. This set-up required much more bandwidth to operate, and CNN Newsource sent out video in a continuous 16- to 17-hour analog feed each day. Now, the digital video feed goes out in bursts over GE 3, while a simultaneous low-resolution recording is made of the outbound digital feed. The low-resolution version is beamed out on a separate transponder to news producers who view the low-resolution video with its time code, and then select the news they want to air by pulling up the high-resolution versions using video clip IDs.

"The low-resolution browsing system is dumped into a Kencast Fazzt hot folder, and the contents are then mirrored to all the affiliates via IP multicast. Kencast software controls all the drives," Fantz says.

"IP is still very new, with new standards coming out all the time," says David Price, HDS’s vice president for business development. "Video streaming in IP multicast is rapidly developing into the new killer app. The range of applications is quite broad. Among the simplest applications are both the delivery of linear and non-linear video files and streams. Bubbling up alongside of these are the virtual private network applications, interactive distance learning (IDL), telemedicine and Intranet connectivity."

"We want to see ‘Powered by Cyberstream’ as common in broadband networks as ‘Intel Inside’ is in the PC world," Price adds, as he highlights the tremendous strides made by HDS in the area of IP multicasting over satellite in particular.

Among other things, the HDS Cyberstream Enterprise1 router/receiver has been selected by STM Wireless in Irvine, CA, as part of its new Spaceweb two-way VSAT system, a fully IP multicast-enabled platform. Besides STM Wireless, CNN Newsource and the above-mentioned Sunysat pilot project, HDS’s Cyberstream TRX Gateways and SAT1 PCI/PC cards have been selected by host of international satellite players such as Panamsat, Teleglobe, Loral Cyberstar, Satcast, Seachange International, IP Planet, Video Networks Inc., Europe Online, Interpacket and Satcom Systems. HDS is also partnering with Irdeto Access (Mindport) to incorporate Irdeto’s IP scrambling system into Cyberstream.

Driving E-Commerce

Large MPEG 2 video files require delicate care, and being able to guarantee delivery of these immense blocks of IP data on a one-shot basis represents a quantum leap forward. Boosting the confidence level in the emerging e-commerce realm is not the only reason Stamford, CT-based Kencast Inc. developed its Fazzt Forward Error Correction (FEC) technology. The company also wants to reinforce existing networks as routine file transfers and data streaming take off in a wide range of new applications such as corporate Intranets, Extranets, BTV overlays, and kiosks.

"With standardization, the market is drastically different. There are more than 15 major PCI IRD card vendors, and prices for their satellite cards have fallen below $300 per card. Video playback cards can play back MPEG 2 very well, and they are having an enormous impact on the desktop video side," says William E. Steele, Kencast’s president. "In addition, IP multicast software is everywhere, and PCs with upwards of 38 GB of storage are becoming the norm. This represents the IP foundation for real, mass-market applications.

"And as these mass markets emerge, building a business plan around a return signal or any form of ack-nack (this is a reference by Steele to any form of return path-based acknowledgement/no-acknowledgement sequence in the data feed) is not technically or economically practical," he adds.

Kencast is essentially an FEC middleware provider that prefers to remain as transparent as possible. With Kencast’s Fazzt, the user can make repairs to damaged content in a file or live stream from seconds up to minutes in length, according to Steele. Kencast introduced Fazzt 6.0 at IBC ’99, and Steele indicates that Fazzt 6.0 incorporates a fundamentally different underlying infrastructure. Fazzt 6.0 propels Kencast well beyond its established leadership in terms of ultra-reliable broadband delivery, opening the door to a new class of fault-intolerant applications in the process.

"We can protect live feeds as well as file transfers, regardless of the streaming or Webcast software involved, such as Realvideo, Zing, Netshow, etc. Content providers get back exactly what they hand us," Steele says. "We realized that traditional FEC would not work. Like Dolby, which takes the noise out of music, we take the noise out of the satellite feed. Reed-Solomon FEC, for example, works only at the bit level, and while it deals well with random noise, there is no possibility of validation, and no way to tackle extended outages in the manner that Fazzt addresses and solves them."

Steele emphasizes that the outage problem is becoming more critical for a variety of reasons, and not simply because rain for years has traditionally been a four-letter word in the vocabulary of the satellite industry.

"As we move from C-band and Ku-band to Ka-band, the spectral waves which were once a city-block long are now less than the diameter of a raindrop, so heavy rain absorbs the waves and causes outages. At the same time, as I indicated a moment ago, the shift to a mass market means the files are becoming much bigger. Finally, the growing emphasis on mobile satellite transmissions means that terrain-related reception issues are becoming more significant," Steele says. "Besides, the Internet is exploding and it is completely open. Satellite is going to continue to play an enormous role in the Internet backbone, where there will be no room for proprietary technology. Fazzt works with any standards-based DVB equipment."

Fazzt currently ships with 140-plus applications off the shelf, according to Steele, who indicates that Kencast has well over 300 customers worldwide. Besides the above-mentioned Sunysat pilot project, other ventures using Fazzt include Atlanta-based College Television Network, where General Instrument Digicipher 2 4100 encoders are deployed, and People’s Einst Bank in Germany, which uses Israel-based Tadiran encoders and Fazzt to reach 1,600 sites in a satellite network integrated by Thyssen. Loral Cyberstar also uses Fazzt as part of its Worldcast service for the multicast distribution of large file transfers involving all kinds of media, multimedia and data.

Optimizing Enterprise Applications

Using standards-based and proprietary protocols, Fourelle Systems in Santa Clara, CA, focuses on data compression and protocol optimization to achieve significantly faster throughput for IP-based applications over satellite, according to Patrick Glenn, chairman and CEO of Fourelle Systems.

"Fourelle Systems’ Venturi Transport Protocol, or VTP, offers value in network environments where efficiency, speed and bandwidth are significant issues. We are leveraging our core competency in Web acceleration," Glenn says. "We believe that you have to understand the application to make it smart. VTP is an UDP-based transport protocol, and UDP is absolutely blind. UDP is not like TCP, with lots of acknowledgements. With Venturi, we have built an intelligent protocol that does not send traffic if it does not have to.

"Our solution is targeted for enterprise applications, not video applications, although we would consider using MPEG 4. We can handle speeds up to 6 Mbps. We operate both on the remote side and on the enterprise side, where you find T1s and T3s," Glenn adds. "With VTP, we reduce the amount of transmitted data by as much as 85 percent."

Increasing the amount of bandwidth by adding more T1s, or putting more servers in place, does not solve the congestion problem by itself, according to Glenn. This is an expensive solution that is avoidable. After all, Glenn points out that going all the way to a DS-3 (45 Mbps) will not solve the problem. High latency will persist and, in many instances, the DS-3 simply adds to rather than helps to overcome the nagging problem of congestion on the network.

"In a satellite network, the ideal placement for Venturi is as close to the application server as possible. We put what we call our Venturi Compression Server on the enterprise side, and the Venturi Personal Client or Workgroup software at the remote site," Glenn says. "Using this model will enable us to build services on top of the same platform."

Venturi Personal Client software works with Windows 95/98/NT4.0, Mac OS-8, Solaris and Linux. In August, Fourelle Systems added Venturi Workgroup Client software to its product line, thus eliminating the need to perform time-consuming installations on all PCs tied into a specific workgroup LAN. A maximum of 50 Windows-equipped PCs can be supported using a 10/100 BaseT Ethernet interface. The Venturi Workgroup Client-equipped host PC can run at speeds ranging as low as 14.4 kbps up to speeds in excess of 1.5 Mbps.

Atlanta-based Scientific-Atlanta selected Fourelle Systems Venturi when it installed a 225-site Skyrelay.IP-based VSAT network for Saab Cars USA Inc. in Norcross, GA, which extends out to 1,200 PCs nationwide. This Intranet-based Retailer Information System (IRIS) runs at 1.5 Mbps, although it can run up to 4 Mbps, according to Mark J. O’Shaughnessy, Saab Cars USA’s manager for retail systems. IRIS was designed to achieve operating cost reductions of 75 percent when compared to terrestrial alternatives.

"We’ve gone with an unusual solution. We have no server at the dealerships, so it is completely thin on the other end. We are pumping this IP into the dealership, and Fourelle makes this possible. It has really made latencies insignificant," says O’Shaughnessy. "We finished the rollout in late October, and we are certainly planning to upgrade this network."

New Modulation Techniques

Barry Hobbs, director of engineering and field support at Tandberg NDS in Newport Beach, CA, sees a lot of exciting developments on the horizon as modulation techniques, in particular 8-PSK, evolve. Back in September, Norway-based Tandberg Television ASA acquired all of U.K.-based NDS’ digital broadcasting subsidiary, known as DBB. One result of this transaction, subject to approval, is that News Corp., the parent company of NDS, will have a 20 percent stake in Tandberg.

"New modulation schemes are bringing lots of enhancements to the pipeline, both satellite and fiber. We are seeing these specific modulation techniques being implemented in silicon. The shift from QPSK to 8-PSK involves increasing capacity by about one-third, for example. Going from 2 bits per hertz with QPSK to 3 bits per hertz with 8-PSK means that the average 36 MHz C-band transponder, which previously operated at 50 Mbps, can now handle upwards of 80 Mbps," Hobbs says. "Another option is 16 QAM, which involves a substantial factor gain when another 2 dB of power is added."

Hobbs points out that while the transponders that handle QPSK today can handle 8-PSK too, this transition requires an additional 4 dB of power. This increase in power can be attained either by deploying higher-powered satellites or larger Standard A-type dishes. As a result of this higher cost barrier to implementation, Hobbs sees a shift to 16 QAM as more feasible, and expects it to precede any industry-wide shift to 8-PSK by a few years.

"Large enterprise broadcasters may already have the larger antenna base installed, and so they currently have a margin of 5 to 10 dB to play with. They can achieve payback in two to three years by making the jump to 8-PSK, as opposed to maintaining current modulation techniques over any existing transponder with a ten-year lease," Hobbs says.

According to Hobbs, the advances in modulation techniques are right in stride with gains in forward error correction, and over the next 18 to 24 months, Hobbs believes that even more impressive results will be achieved as more efficient encoders requiring fewer bits appear on the market. Hobbs attributes much of this substantial progress to the explosion in the digital television market and the need to address rapid motion sports programming as part of the DTV equation.

"Encoding is all done at far better rates today. Over the past year or so, the digital video component of HDTV was running around 18 to 18.1 Mbps out of the total ATSC stream of 19.39 Mbps. Now we are seeing the data rate for video dropping to 14 Mbps for things such as sports," Hobbs says. "As far as HDTV movies are concerned, we have seen the video in 1080i/24 drop down as low as 10 to 12 Mbps, while 720p video is now down in the 7 to 8 Mbps range. And just as we are seeing the video rates coming down, similar changes in audio are also taking place."

When National Technological University Corp. (NTUC) in Fort Collins, CO, decided to recently upgrade its nationwide satellite network, which links dozens of downlink sites to more than 40 universities that have their own satellite uplinks, NTU selected the NDS E5610 encoder.

According to Andy Casiello, NTUC’s vice president of delivery technologies, with what he describes as "the usual start-up teething problems" now behind them, NTUC is looking forward to exploiting E5610’s broad range of capabilities.

"The real benefits, in addition to the image and audio quality, will come into play in the near future, when we begin exploiting the desktop delivery capabilities of the MPEG 2 system. We’re in the beginning testing phase of the PC receivers, and other techniques which will allow us to deliver very high quality content to the desktop," Casiello says.

"Regarding the decision to use NDS equipment, we are very pleased for a number of reasons, including the combination of image quality at low bit rates; the efficiency of the RF aspect of the DVB system, which allows for the use of smaller, inexpensive antennas; and a terrific range of computer and set-top receivers," he adds. "The flexibility of this suite of NDS software and hardware for data delivery along with the addition of IP encapsulation capabilities makes this the perfect system for NTUC."

Casiello indicates that NTUC is also exploring the use of the NDS Mediastorm system. Mediastorm handles the scheduling and delivery of media.

Breathing New Life Into Existing Infrastructure

J. Mitchell Robinson, president and CEO of Viacast Networks Inc. (formerly Intelligent Devices Inc.) in Ijamsville, MD, likes to point to what he sees as the single unifying force in the world of satellite communications.

"We understand that everyone is like us, a thrifty organization, and we are trying to take their infrastructure and breathe new life into it. We don’t see any need, except in extremely rare circumstances, for anyone to gut their existing infrastructure," Robinson says. "Our first product, the Corridor, was a non-DVB, high-speed data broadcasting engine for leveraging existing VSAT and BTV satellite networks. And yet even then we were able to see where the market was going, and that it was very important to move into the DVB arena. So, we introduced our IP-Companion 6500, which is an MPEG 2/DVB high-speed data broadcast receiver and IP router.

"At a time when both multicast and high-speed unicast IP networks are taking off, we have to be able to sustain and support both simultaneously. And we achieve that with the IP Companion 6500 as well as our other products," Robinson adds.

Viacast Networks is a tiny company with only 16 employees that has attracted a curious mix of clients over the years, including Ford Motor Company, Echostar Communications Corp., Merrill Lynch, TVguide and Skycache, to name a few. There may be no common thread, but with Viacast Network’s input, the results seem to be the same.

"We fought our way in, knocking down the barriers to entry by diversifying our product line," Robinson says. "It is all about positioning, and knowing how to be more cost-effective."

Viacast Networks does not openly state that it relishes the challenge of creating customized solutions for its clients. But after a discussion with Robinson and a look at Viacast products and specifications, it is clear that there is ample room for Viacast to dovetail the finished product to meet any network’s operating requirements. For example, Viacast Networks created a special version of its Turbolinx Broadband IP Router, which features a 12-MIP processor that can handle up to 54 Mbps, for Echostar’s Dish Network Business Television, according to Robinson. Turbolinx features an HTTP Daemon for remote command and control, and it can support DVB multi-protocol encapsulation. In this instance, the result allows for total mobility and portability

Among other things, this permits Echostar to beam its Dish Network BTV programming directly to any laptop. It represents a classic case of win-win.

"You cannot put a PCI card in a laptop. So, we made a version of our Turbolinx that is specifically ported to Echostar’s receivers. This allows Echostar to do high-speed IP direct to the PC or the laptop in the user’s home using their standard DVB-based DBS feed, while also allowing them to handle business-to-business networks," Robinson says. "Now, they can walk in to a prospective BTV customer and say, ‘All you have to pay for is the data service and the data module. We don’t crack the PC or load special software, and you can do a multi-Megabit download instantly.’ The added benefit for Echostar is that the customer’s work force also becomes part of Echostar’s DBS customer base."

"We’re pleased to be working with Viacast on a business to business communications solution for Echostar’s business television clients. With Viacast’s technology, we can deliver streaming video and large amounts of data materials to our clients who need to provide training materials to their employees," says Doug McGary, data products manager at Echostar.

With a new name and a recent injection of funds from two venture capital groups, Robinson intends to continue Viacast Networks’ successful track record.

"We are in the business of offering service providers and enterprise customers a comprehensive broadband IP solution over satellite," Robinson says. "This is our mission today. Tomorrow we intend to support other broadcast media with new technology which is just beginning to roll out of our development group."

Encapsulating And Encrypting IP Multicast

San Diego-based Logic Innovations Inc. introduced its IP Encapsulator Data Gateway (IPEDG) last year in order to tap quickly and effectively into the rapidly expanding market for IP multicast solutions in the IP data broadcasting sector. IPEDG represents a strong follow-on to Logic Innovations’ Data Stream Transport System (DSTS). With open network architecture rapidly displacing proprietary solutions at a brisk pace, the company believes that its DVB-based IPEDG is in the right place at the right time.

The IPEDG feeds the DVB compliant transport stream to a DVB-S modulator, such as the EF Data SDM-2020, and then it passes on to an upconverter and HPA, such as the Radyne Comstream CUC101. Any DVB receiver, such as the Philips Clevercast, Broadlogic Satellite Express or Viacast Networks’ IP Companion, can be accessed through the IPEDG.

Last May, Madrid-based Infoglobal S.A. used an IPEDG to transfer a 29 MB file at just over 1.9 Mbps. Using 2 Mbps of transponder bandwidth on Hispasat, with a 28.8 kbps return channel and no protocol spoofing, the estimated round-trip packet time was 300 ms or less during this trial run.

"We have taken a network-centric approach to IP encapsulation. Our IPEDG should be viewed as a specialized router. In this regard, it looks much more like a Cisco Systems router in a satellite headend," says Fred Kokaska, Logic Innovations’ product manager. "We address concerns such as latency reduction with our hardware solution where we can easily achieve performance improvements of two orders of magnitude. And then there is the question of managing Quality of Service. With our very user-friendly graphical user interface (GUI), it is easy to set minimum and maximum user rates on what constitutes our router table. This GUI replaces lots of reference books."

Logic Innovations is focused on the systems integration and OEM level, according to Rene Savalle, director of sales.

"Right now the limit for our IPEDG is about 70 Mbps. In fact, we are far outrunning any of the receivers on the market today in terms of throughput speed. How soon 8-PSK receivers will appear on a widespread basis is unclear, although we know that 8-PSK gives you 35 percent better throughput. With your typical 36 MHz transponder, that amounts to a big jump from 60 to 70 Mbps up to 90 to 100 Mbps," Kokaska says.

In September at IBC ’99, Logic Innovations and Mindport’s Irdeto Access teamed up to demonstrate the IPEDG with an integrated IP unicast and multicast scrambling system. The encryption of IP data in an IP multicast mode, for example, means that users can be addressed on an individual basis.

"The beauty of this is that you are encrypting the information, not the header, so it winds up completely transparent as it passes over the network. It is routed normally, and it uses a rotating key system. This Irdeto conditional access system is not a conventional PID-level access control system," Kokaska says. "We have provided the integration hooks. All the subscriber management tools are operating on the same interfaces as the GUI."

Kokaska agrees that the cache update model is popular among Logic Innovations’ customers.

"The companies that offer cache services know what a router is, and they also have server farms so they want to generate high-bit-rate traffic. It does not matter if the traffic is unicast or multicast, TCP or UDP," Kokaska says. "Beyond that, another trend that is just beginning involves TDMA system operators using IP encapsulated data to replace TDM data to take advantage of the push capability. A lot of traditional-type services are finding that the performance and cost is very attractive." In December a majority interest in Logic Innovations was acquired by U.K.-based Xyratex International, Ltd.

Echo Control Is Essential

Ditech Communications Corp. in Mountain View, CA, is a leading provider of echo cancellation technology. Ditech has introduced Far End Echo Cancellation (FEEC) which is designed to address the specific needs of the satellite industry. Customers come to Ditech primarily for voice quality solutions whenever the network-inherent delays produce unwanted echo or propagation noise. Larger, more pronounced echoes adversely impact voice traffic on geosynchronous satellites due to the long transmission times involved. Delays are part of the LEO equation as well. For example, the LEO-based Iridium system has 210 ms of delay in its network.

According to Tim Hult, Ditech’s senior product manager, in a standard geosynchronous satellite path, the propagation delay alone is at least 270 ms and can easily be in excess of 540 ms for the large hub and spoke VSAT configurations, which constitute the bulk of satellite-based virtual private networks (VPNs). This problem is eliminated when using Ditech’s 624 FEEC, which features 624 ms of available path cancellation, or Ditech’s Global Span which Hult describes as "a super-FEEC" which can accommodate 2 seconds of path delay.

"For double hop satellite networks or single satellite hops with an undersea cable links and local RBOC termination, our Global Span will handle up to 2 seconds of path delay present in these satellite networks," Hult says.

Delays introduce echo into the network far in excess of what constitutes normal provisioning. In terms of terrestrial echo control, both standalone echo cancellers and echo cancellers that have been integrated into switches, normal provisioning is in the 64 ms to 128 ms range, according to Hult.

"Most commercial C- and Ku-band satellite operators do not provide echo control as part of their lease services, leaving the customers to manage their own voice quality. With Ditech’s FEEC or Global Span, you can deploy all the necessary echo cancellation for your network in a single gateway hub site. This can lower costs and simplify deployment. This adds a lot of flexibility for existing satellite networks, and for the new generation of Ka-band satellites too," says Hult.

Hult points out that the first generation of the new Ka-band birds, such as Spaceway and Astrolink, will do their packet routing on the ground using ATM or IP switches, and this will add to the path length for these networks as well.

"The key thing for us is that we are currently deploying echo cancellers in terrestrial packetized (ATM, IP, Frame Relay) virtual private networks (VPNs) and carrier class networks now. There is no reason to think that we will not see them in satellite networks as well. Our customers tell us that the issue of voice quality is a big part of achieving low customer churn rates for both the wireline and wireless telephony market," Hult says.

"Furthermore, we are finding that while many of these new packet switches or gateways advertise the fact that they have echo control on board, the service providers are finding that this capability is insufficient for a number of reasons. These reasons include not enough delay capacity-64 ms is typical-or what we refer to as not a long enough tail, or not enough processing capacity as the switch load approaches peak levels," Hult adds. "Hence, end users may want to consider incorporating their own discrete echo control to protect the voice quality of their service over a wider range."

It Doesn’t Stop Here

These satellite network performance-enhancing companies are making the satellite sector a place where anything is possible. We have mentioned just a few, and yet numerous other companies are in this race as well. For example, Ottawa, Ontario-based International Datacasting Corp.’s (IDC) Superflex system, together with Skystream Corp.’s DBN-26, Kencast Inc.’s Fazzt and Broadlogic’s satellite receiver cards have been selected by Loral Cyberstar for its broadband Internet backbone infrastructure known as Worldcast.

For Ron Clifton, IDC’s president and CEO, the satellite networks that are on the cutting edge of interactive distance education stand to benefit enormously, both in terms of flexibility and operating costs, when they adopt the performance enhancement technologies such as those identified in this article. And interactive distance learning ranks very high on Clifton’s list of priorities of hot growth areas in urgent need of attention.

"This is essential for the information technology work force of the future. We are witnessing the migration from talking heads to convergence at the desktop. This is a model where the student who wants information can access it using browsers, e-mail, and viewers to engage in self-teaching," Clifton says.

With two projects underway in Mexico, including one with the Virtual University in Monterrey using Satmex 5, as well as other projects unfolding with companies such as Telesat Canada and Spain’s Telefonica, IDC has taken an aggressive global approach. Bedford, U.K.-based Kingston Satellite Services used IDC’s Superflex to get a head start in the European Internet via satellite market in late 1998. Beyond rolling out a new dimension in IDL technology, IDC is an emerging satellite networking superstar that can provide the complete end-to-end DVB-based solutions, including IDC’s SR2000 receivers and Echonet software.

Los Angeles-based Mentat Inc. is another good example. Mentat’s TCP over satellite performance technology lies at the heart of Mentat’s SkyX Gateways, including a new high-speed version, Mentat’s XH45. For example, Inter Universities Computation Center (IUCC) in Israel recently implemented the first global satellite link to the Internet 2 network, using Mentat’s XH45 and a 45 Mbps link on Intelsat 801 to tie into academic institutions in the United States.

Companies such as Starburst Communications, Imedia, Helius, Adaptive Broadband, Combox, Xedia, Radyne Comstream and V-Bits-which has been acquired by Cisco Systems- are also companies on our constantly-growing list of satellite network performance enhancers.

All of the companies mentioned above may not dominate the satellite industry, yet they have been instrumental in propelling the satellite industry to new heights. These companies have been providing their customers with a new set of tools to do the job, while saving them a tidy sum of money in the process. Happy, satisfied customers who have confidence in their vendors tend to spread the word, and a few more satellite transponders might be required to handle the surge in traffic as all these satisfied customers fan out across the countryside.

Peter J. Brown tracks the global satellite industry, focusing primarily on Internet and multimedia applications. He lives on Mount Desert Island, ME.

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