Introduction

SkyFrames, Inc. is pleased to offer a turnkey system for the supply of Two-Way broadband communications. SkyFrames is continuously developing advanced broadband satellite systems to allow reliable, efficient communications at a low cost for the growing IP base market. 

The SkyFrames proposal is based on the companies own developed and commercially available SkyFrames system. The SkyFrames system has an extensive customer base with leading satellite service providers.

SkyFrames proposal is fully compliant to the RFP, meeting all requirements and in some cases, exceeding them.

1 Advantages of choosing SkyFrames Integration 

The SkyFrames Proposal offers many advantages including:

1. No Development needed. System is already available through other major service providers and has mature market base.
2. Cost effective: Forward DVB carrier share the same resources.
3. Fast delivery schedule allows for fast deployment.
4. Turnkey system uses SkyFrames as single primary supplier.
5. Reliable & cost-effective integration.
6. Modular and scalable solution for current and future needs.
7. Company dedicated to the continuous development of IP based products via satellite.
   
   SkyFrames is engaged in the development, integration and sale of state-of-the-art satellite communication systems. 
   
   SkyFrames is among the first company that adapts and offer a line of satellite L-band modems in both variable and burst capabilities. The modems implement the latest in DSP technology, algorithms, FPGA, and direct digital synthesizer components, all on a dual compact digital board. Since SkyFrames introduced these modems, other satellite communication companies have invoked the L-band philosophy, which became a standard for all VSAT and Broadband systems. L-band technology was embraced for its reliability and cost.

Figure 1. SkyFrames L-band Modulator / Demodulator Digital Cards

The modems were designed for VSAT and Hub stations for variety of online applications such as voice, data, and video. The L-band modem provides full support to the outdoor Remote Frequency Terminal (RFT). SkyFrames also introduced a low cost VSAT for satellite networks using low cost Block up-Converters that use L-band IF input and convert to standard Ku-band or C-band frequencies. The development objectives of this project were successfully achieved by mid-1998 by its Manufacturer. During the project, the company developed a proprietary innovative technology and a novel system architecture, which resulted in a significant cost reduction of the modem and the complete VSAT. 

SkyFrames Two-Way via Satellite Broadband Network System SkyFrames was again among the first company to commercially offer a Two-Way via satellite broadband network system that is fully IP based. The SkyFrames system incorporates the DVB-S / MPEG2 (Digital Video Broadcasting for Satellite / Moving Picture Experts Group) as the broadcasting waveform mechanism to allow multimedia streaming of Video, Data and Voice on a single wideband channel. The Return path, also via satellite, uses SkyFrames L-band modulator/ demodulator technology. SkyFrames has also adapted to the development of its own Network Management System that uses a Bandwidth On Demand protocol with a DAMA (Demand Assigned Multiple Access) controller to efficiently use and control satellite frequency resources. 

The SkyFrames platform provides voice and data services (including Video Multicasting) for local and regional Internet Access & Service Providers (IAP, ISP), Small Businesses, and Shared Facilities in business campuses, universities, Local Area Networks (LAN) and Wide Area Networks (WAN). All LANs are connected under a star configuration to a central Hub that can share multiple users. The SkyFrames Remote Gateway uses a standard Ethernet connection protocol allowing easy installation under a LAN environment. The system can be easily integrated into the existing phone infrastructure to provide both the VoIP and data services required. The proposed system offers the subscriber an efficient, reliable, and cost effective solution in accessing multimedia services and eliminates the long delays in accessing the Internet.

 Back To The Top

General Overview

2 General

The SkyFrames system was designed from the beginning as a Two-Way via satellite fast Internet access system. The system’s superiority lies in its unique features, which are described below. 

1. The SkyFrames system has a DVB-S compliant forward link from the SkyFrames Hub to the remote terminals, which enables multiplexing of TV and IP over the same signal and enables users to receive TV and IP with the same antenna and equipment. This allows customers to add the SkyFrames Hub to existing Digital TV Hubs with marginal investment. 
2. The SkyFrames Forward link data rates are between 2.0 - 72 Mbps. This enables the service provider to start with a network that leases small portions of the space segment and later expand the network with a simple NMS command. 
3. The SkyFrames Return link from the RG-384B Remote Gateways is configured, on the fly, for data rates of 16-384 KBPS. This enables small enterprise connections as well as local ISP connections to the Internet backbone.
4. The SkyFrames Remote Gateway is designed to provide the basic routing features and capabilities needed to support Local Area Network users. The Remote Gateway can be connected to Ethernet hub, which enables multiple users to connect to the Internet
5. The SkyFrames Remote Gateway includes the latest technology in satellite communications such as an L-band IF interface, low cost Block Up-Converters, and standard DRO LNB units. This creates an exceptional price/performance ratio.
6. The SkyFrames system comes with a state-of-the-art Network Management System and provides Demand Assigned Multiple Access (DAMA) and Bandwidth On Demand (BOD). 
7. The SkyFrames system measured data rates per un-accelerated TCP/IP session of 1-1.5MBPS. The user can have several TCP/IP sessions running on his computer all supporting these data rates. 
8. The SkyFrames system delivers IP (Internet Protocol) over satellite, ensuring compatibility with any user application. 
9. The SkyFrames system and Remote Gateways support multiple private and standard IP addresses. This provides flexibility in the network and resource allocation and design.
10. The SkyFrames system has been tested with the following applications: Netscape, Explorer, other browsers, FTP software, Video Conferencing, Voice over IP, Distance Learning, IP/TV, Real Video/Audio, VPN, IPSEC, PC Anywhere and others. The system’s open network design allows it to deliver any IP based application. 
11. The SkyFrames system supports Multicasting to the Remote Gateways. 
12. The SkyFrames network was designed to support QOS on both the Forward and Return links with flexible capabilities. 
13. The SkyFrames system can be provided with accounting and billing software.
14. For the Voice Over IP user a Gatekeeper provides authentication of calls. It also provides the pre-paid calling card administrative capabilities.
15. The SkyFrames system is the focal point of the company’s efforts, thus ensuring future advanced features and capabilities.

There are several other unique features, but we believe that the list provided above will lead you to the conclusion that the SkyFrames system provides the most advanced and complete solution in the market today. 

In this document we have provided a technical description (high level) of the SkyFrames system.

Back To The Top

Overview

3 System Description

SkyFrames is a Two-Way Communications System via Satellite that provides Fast Internet and Interactive Multimedia, as well as a wide variety of IP applications. The SkyFrames system enables end-users and service providers to bypass terrestrial communication bottlenecks, thus a fast and reliable solution. The SkyFrames system supports all IP transport protocols: TCP/IP, UDP/IP, unicast and multicast addressing. 

Integrating the Remote Gateway units with base-stations of a Wireless-Data system can extend the range and capability of the remote units to provide service to users located up to 13 KM from the remote units. This implementation is especially useful in suburban and rural scenarios, as the price per single user is dramatically reduced by connecting to a wireless remote unit instead of connecting to an SkyFrames Remote Gateway. There are additional solutions (e.g. EDSL for building connectivity for residential users) to maximize the full performance of the Remote Gateway and to reduce price per user. SkyFrames will plan for each scenario the optimum solution to achieve the above goals. The wireless-satellite integrated system is useful also in buildings shared by many individual users.

A partial list of applications that have been actually tested within the SkyFrames system includes Internet access - TCP/IP, FTP, HTTP, Voice over IP, IP/TV, Real Video/Audio, Distance Learning, VPN, IPSEC, protocol accelerators, and more. 

The SkyFrames system may be configured as a one-way via satellite, with a terrestrial return link, or a hybrid system.

The SkyFrames is a star configuration system. It is comprised of a central Hub and remote terminals, called Remote Gateways, which enable Two-Way communication.

SkyFrames enables multiple users to enjoy multimedia applications at unprecedented speeds. Its Forward link DVB-S/MPEG-2 technology can transmit data rates between 2-72 Mbps. A Remote Gateway can handle traffic of 15 Mbps, processing up to 1.1 Mbps per TCP/IP session and more, if accelerated. The Return path from the Remote Gateway to the central Hub, also via satellite, offers data rates of up to 384Kbps and optional rates of up to 2 Mbps for each terminal. 

Using the DVB-S technology for the Forward link enhances the efficiency of the space segment usage because of the natural feature of broadcasting information to multiple users. 
The SkyFrames Network Management System (NMS) enables dynamic channel assignment of the Return channels for each Remote Gateway by using Demand Assigned Multiple Access (DAMA), and Bandwidth On Demand (BOD).

Back To The Top

SkyFrame Remote Gateway

4 SkyFrames Remote Gateway
The SkyFrame is shown in Figure 4.

Figure 4 –SkyFrame Remote Gateway general view

4.2.1 Remote Gateway Hardware
The SkyFrame Remote Gateway is a terminal consisting of
· Industrial PC housing
· DVB receiver card
· FDMA modem based on a unique patented technologies
· 10/100 Base T NIC
· Dial-up Modem
· SkyFrame software - The SkyFrame software serves as an agent of the NMS to control the hardware. In a later section, there is a detailed description of the Remote Gateway capabilities and the SkyFrame software.

A typical installation with the SkyFrame is shown in figure 5. 

Figure 5 – SkyFrame Remote Gateway on shared Video Carrier

The Remote Gateway is composed of indoor and outdoor units. The Remote Gateway Indoor Unit is an Industrial PC-based unit, including a DVB-S receiver for the outbound received signal, with a LAN processor, a satellite L-band modulator and supporting units such as power supply and 10MHz reference for the outdoor unit, Ethernet LAN with 10/100BaseT interface. The SkyFrame Gateway is designed to receive data rates of 2-72 MBPS process up to 15 MBPS (data rate per unaccelerated TCP/IP session of up to 1 MBPS) and transmit data rates of up to 384 KBPS with the standard offering The Remote Gateway Outdoor Unit (ODU) consists of a Block Up Converter, a standard DRO LNB and an antenna. 
Two elements that manage the Return channel allocation reside in the Remote Gateway:
· SkyFrame – Remote Network Management Agent – software package that communicates with the NMS and receives the list of available FDMA channels.
· Traffic Analyzer – continuously measures the inbound traffic from users.
When the traffic analyzer senses inbound traffic data sent by the users, it reports to the SkyFrame. The SkyFrame then requests a channel from the available channel list, with bandwidth according to the measured traffic. If the bandwidth measured by the traffic analyzer changes, the SkyFrame requests a new channel in accordance with the updated bandwidth.

The modulator at the Remote Gateway uses advanced Digital Signal Processing (DSP) technology, housed on a compact digital board. The unique L-band interface (950-1525 MHz) reduces SkyFrames Remote Gateway cost and allows exceptional price-performance ratio. 

SkyFrame Remote Network Management Agent .The SkyFrame Software resides in the SkyFrame Remote Gateway. It controls the operation of the transmitter and receiver inside the Remote Gateway. It supports the initial connection to the network and monitors the activity of the LAN users. The SkyFrame enables the NMS to control the Remote Gateway. It continuously monitors the M&C messages broadcast over the DVB Forward channel by the NMS and acts accordingly.

End User Configurations The Remote Gateway provides an RJ-45 Ethernet 100 Base-T output; this gives the unit very high flexibility. Within in a system, each terminal may be configured in a different manner. In most cases, the LAN equipment located at one Remote Gateway communicates directly either with equipment at the Hub or at another Remote Gateway.

4.2.1.1 VOIP
For a system with Voice Over IP capabilities, the equipment at the remote site depends on the amount of voice traffic. If only a few call are required, and the local site does not have a PBX, then FSX equipment best suits the customer needs. 

On one side a standard telephone connects directly to the FXS equipment. On the other side, the FXS equipment connects directly to the Remote Gateway LAN.

However, this is not the only possible configuration. The VOIP portion of the terminal comes in multiple configurations to fit the needs of the site. The FXO and FXS units are available with these features and options:
· Embedded hardware design
· 2 and 4 line options
· 2 line unit with option to convert both lines to FXO or FXS
· 1 or 2 Ethernet ports
· Selectable code
· Selectable sampling rate

The basic carrier units comes with the following features:
· Embedded hardware design
· E1/T1 selection
· Supports all well known signaling protocols
· Clock can be configured as master or slave
· Versatile configuration


4.2.1.2  VPN
The figure below shows a typical installation with a VPN appliance. The public leg of the device is connected to the Remote Gateway. In this case, the network device has two interfaces. One interface supports a secured network and the other does not. The networks can operate on registered public IP addresses, NAT, or the device can provide addresses using DHCP.

4.2.1.3 Videoconference
IP based Video Conference equipment is another end user option. For decent quality audio and video, a bandwidth of between 128-256 KBPS is required. These data rates are within the working range of the Remote Gateway. Video Conferencing is a two-way application.

The specific equipment depends on the user requirements. The figure above shows videoconference equipment with a non-IP output. In this case, the videoconference feeds a television monitor.

Back To The Top

General Principle of Operation

5 General Principle of Operation

5.1   Access Method and Basic BOD Operation

5.1.1   System Physical Layout
The SkyFrames system is a star-based asymmetric network. 

On the outbound link, the SkyFrames Hub transmits a shared TDM (Time Division Multiplexed) DVB-S (Digital Video Broadcasting – Satellite), MPEG-2 compatible signal at data rates of 2-72Mbps. All Remote Gateways receive the same signal. The outbound signal is used to transmit data pushed and pulled to/by the Remote Gateways, and to transmit control data to the Remote Gateways.

On the inbound link, the Remote Gateway uses a SCPC (Single Channel Per Carrier) FDMA (Frequency Division Multiple Access) carrier with data rates of 16-384 KBPS for transmission of data and networking commands to the Hub. What is unique about the SkyFrames system is that both the operating frequency and the bandwidth are dynamically assigned.

5.1.2   Bandwidth Management
The NMS provides bandwidth management in an on-demand environment. Bandwidth management is provided on a single or multiple transponder basis. All space segment portions dedicated for Return channels are shared among the active users and are available for new demands. Sharing is based on an FDMA scheme where each Return channel has its own carrier frequency and bandwidth.

The Return channel bandwidth can be any fraction of a transponder. The SkyFrames system allows for the DVB carrier and the Return channels to be located on different transponders. Also, the return channel bandwidth can be in multiple non-contiguous segments.

5.1.3   Connection Channel Assignment
During system configuration, the start frequency and stop frequency to be used for Return channels is entered into the NMS. The NMS generates a list of connection channel. The list is broadcast over the DVB channel to all Remote Gateways.

The frequency channels are assigned to each Remote Gateway by DAMA (Demand Assigned Multiple Access) only when actual data is sent from the users towards the Hub. The bandwidth of the channel is assigned according to the actual data rate that is measured and is dynamically adapted to the measured data rate. The initial channel assigned to each connection is according to the base system data rate, and then is modified according to the measured traffic. The system operator selects the base system rate according to the service provided. The base system rate is always an integer multiple of 16 KBPS.

The RNMA monitors the users’ requests for connection based on their measured traffic sensed by the traffic analyzer (no dialer is required), and chooses one of the free return traffic channels to transmit a connection initiation request to the SkyFrames Hub NMS. The NMS then sends an acknowledgment command to the SkyFrames remote gateway and updates the list of the free channels that are transmitted every 10 seconds to all of the Remote Gateways.

5.1.4 Bandwidth on Demand Operation
If the SkyFrames senses traffic data rates that are equal or less to the already occupied channel, then the session continues with the same data rate. If the traffic analyzer senses output data that cannot be accommodated by Return channel, then it sends a request for additional bandwidth to the NMS. Assuming that the configuration parameters permit additional bandwidth allocation, the NMS allocates a frequency and new data rate to the Remote Gateway. The SkyFrames software reconfigures the modem to continue transmission on the newly assigned channel. Therefore, the data rates change dynamically during a connection based upon instantaneous needs.

5.1.5 Disconnection Process
When the SkyFrames senses a total cessation of Return channel traffic, it sends a disconnect request message to the NMS. The NMS acknowledges the request. At this point, a number of actions occur. The Remote Gateway ceases transmission. The NMS adds the released bandwidth back into the free channel list making it available to other terminals.

For more information, please see the accompanying white paper describing the advantages of the combination of FDMA, DAMA, and BOD over other access schemes.

5.2 Management
Each element in systems is individually configurable. The SkyFrames system is a closed loop system Intergraded by SkyFrames. Once the Remote Gateway and Traffic Network Management Agent (TNMA) are initially configured, they are managed automatically by the NMS. For connection to a higher-level system, SNMP agents can be made available.

Back To The Top

VOIP Description

6 VOIP Description

6.1 Bandwidth Calculations
Both via satellite and via public Internet bandwidth are expensive commodities. The public telephone system allocates 64 KBPS for a call. In order to save bandwidth, VOIP equipment employs advanced compression and decompression algorithms. The following is a brief explanation of the data rate required to support Voice over IP. There are slight differences between vendors, however the general approach is the same.

The G723.1 is the relevant standard for compression of voice calculation below 

VOIP packets are divided between the header and the data payload (compressed voice). The standard packet size is 118 bytes. Of this (depending on the vendor), the header is 40-46 bytes. The header is composed of four sections: IP header, UDP header, RTP header, and MLPPP header.

While some vendors send packets every 90 milliseconds (11.2 packets per second), others offer variable transmission rates of 30, 60, 90, and 120 milliseconds. Some equipment is auto-ranging in that it finds the optimal data rate for a given pipe.

The data rate calculation for a packet sent every 90 millisecond is:
11.2 (packet/second) * 118 (bytes/packet) * 8 (bits/byte) = 10572.8 (bits/second)

However, in practice the actual value is even lower due to silence suppression. In the event that one side is listening (no voice to transmit), the voice payload is significantly reduced. During silence the data rate may be as low as 6.7 KBPS.

The SkyFrames Voice Sky Gateway supports a return channel data rate of up to 384 KBPS. An E1 line contains thirty time slots of voice. Therefore, the Remote Gateway can transmit the VOIP data produced by a full E1. If less conversations are transmitted, than there is no problem for voice and data to share the same Remote Gateway.

6.2 FXO
An FXO unit does not provide voltage; it imitates a telephone. An FXO unit provides a two-wire analog connection.

The figure above shows a typical FXO VOIP connection at two locations. An FXO unit can either connect directly to the PSTN or it can connect to the PSTN with a PBX in the middle. The drawing also illustrates a simple rule: telephone equipment connects to telephone equipment and IP equipment to IP equipment.

It should be noted that each FXO could communicate with almost unlimited number of other VoIP units. The limitation is essentially the number of locations operated by a single system owner.

Typical FXO-FXO Data Flow and Operation
The best way to understand how a VOIP network functions is to follow a call. A person calling from a telephone anywhere in the world dials the PSTN phone number connected to FXO #1. The FXO box answers the phone and generates a synthetic dial tone. The caller enters a code that defines another VoIP box (for simplicity only one box is shown in the drawing). The call then reaches FXO #2. FXO #2 connects the call to the PBX. At this time, the caller is given two options: he can either dial an extension or enter the digit used to access the PSTN.

Multiple FXO units may be connected to a single PBX. The PBX can define a “hunting group” for multiple FXO access.

6.3 FXS
FXS equipment is active; it supplies voltage to operate a telephone.

A telephone can be plugged directly into an FXS unit. The FXS unit cannot require a direct connection to either a PBX or the PSTN.

When connected to a PBX, an FXS unit simulates a trunk of the telephone system.

Typical FXS Data Flow and Operation
One of the functions performed by a PBX is to determine the cheapest rate to call a specific destination. This is known as least cost routing (LCR). Based on predefined parameters, the PBX selects the trunk that will minimize the cost of the phone call.

A person placing an outgoing call from an extension attached to the PBX will dial a number for outside access (typically ‘9’ or some other digit) followed by the desired phone number. The PBX looks at the LCR table to analyze the number. It can either select the PSTN or the FXS equipment for carrying the call to its destination. The selection of PSTN or VoIP equipment is transparent to the person placing the call.

Using the LCR table is not the only method for accessing the FXS connection. Alternately, the VoIP connection can be selected by assigning the FXS trunk a unique code. For example, a company that uses VoIP for intra-office communication would assign a prefix digit to access the outside offices.

Please be aware that an FXS unit cannot call another FXS unit. It violates the principles of telephone network operation. However, an FXS unit can be matched with an FXO and an FXO can be matched with another FXO.

6.4 T1 Connections
For digital PBX systems, a T1 can be connected to the VOIP equipment. This equipment can use any fraction of the E1 line according to configuration. The equipment communicates with the PBX through the digital signaling on the line.

6.5 Voice Quality
All the technology may be interesting, but the important issue is the sound of the voice. There are many factors affecting voice quality, each in a different way.

6.5.1 Equipment Sound Quality Enhancements
VoIP equipment does not simply transmit voice “as is.” Rather it combines multiple techniques to guarantee the sound quality. Compression and decompression is used to reduce the quantity of data transmitted. This allows data to pass through a smaller pipe, thereby increasing its success of reaching its destination. Echo cancellation is used to remove noise that is generated by reflection in phone lines. Jitter buffering combined with lost packet interpolation cancels out gaps that occur due to packet loss. Taken all together, VoIP equipment provides outstanding sound quality that is far better than that provided in many cases by cellular phones.

6.5.2 Voice Quality and Data Traffic
Voice over IP and other IP traffic co-exist on a single network and compete with one another for the available bandwidth. Proper network design is necessary in order to maintain the voice quality. IP Quality of Service is employed to provide the bandwidth required for the number of calls defined by the customer. The SkyFrames system is compatible with industry standard QoS equipment. In the future, the Remote Gateway will have a native QoS agent to provide VoIP with the bandwidth it requires.

6.5.3 Satellite Delay
It takes just over 250 milliseconds for a signal transmitted from earth to reach a geo-stationary satellite and to return to earth. In a conversation, a speaker anticipates a response. The round trip time is twice the delay of a single direction, a delay of over ½ second.

In the system shown in Figure 2, the Hub has an Internet backbone connection for data communication: a leased line for IP communications with the corporate headquarters, and a PSTN connection for telephone services. A corporation consisting of a headquarters and branch offices use a satellite link for communications. The typical round trip (single hop) delay for a phone call made from the headquarters to a branch office is 600-700 milliseconds. A call from one branch office to another branch office (double hop) is twice as long. Despite this delay, our experience is that customers are very impressed by the sound quality.

One of the factors affecting the quality of the voice is jitter. Jitter occurs because IP networks are connectionless. Calls placed between VoIP equipment within the SkyFrames system are relatively free of the jitter present in the public Internet, resulting in a high quality voice transmission.

Back To The Top

SkyFrames Remote
Gateway Specifications

  Back To The Top