IPSTAR Key Technology on Ground

Air Interface designed for Via-Satellite Broadband Applications

• Forward channel (TOLL)
  
  

  ::	Use of OFDM together with Turbo Coding to minimize overall Power-Bandwidth resources
  ::	Assign Modulation, Coding and Gain per user basis. The parameters can be adjusted by GW per frame basis to allow committed capacity at nominal code rate and high link availability at reduced code rate
  ::	As of today, Bit-efficiency ranges from 0.6 bits/Hz to 2.4 bits/Hz

  
  
• Return Channels (STAR)
  
  

  ::	Five Bandwidth channelization to support different sizes of ODU
  ::	Return Channel Separation of bursty and continuous traffic for better time-slot utilization
  ::	Use of Turbo Coding for Power utilization

Design Concept

The target of our design is to build a broadband infrastructure that increase ability to deal with a broad variety of applications such as internal corporate data, Internet browsing, telephone and entertainment multimedia. This is achieved with fast and economic satellite resources and low-cost ground equipment.

The design of system environment is based on the use of industry standard interfaces, components and solutions. The architecture of the gateway resembles the architecture of an ordinary ISP. Furthermore, the system specific features of the gateway is well understood and implemented within well-defined subsystems. This makes it possible to benefit from the rapid product developments of industry standard products, while ensuring that the gateway as a whole is maintainable and can evolve both in terms of capacity and functionality.

The design of gateway is based on maximum use and adaptation of Commercial-Off-The-Shelf (COTS) products, wherever possible. The COTS products are provided for the following functions in the gateway:

• IP Routers, and internal switches
• Firewall
• TCP/IP Enhancements or Accelerators (TCPA)
• Accounting Server (or Call Record Server)
• XOIP/ PSTN Gateway (option)
• Voice Mail Server & Fax Server (option)
• WAN Router (option)
• Web Server (option)
• E-Mail Server (option)
• Web Caches (option)

Some functions are unique to the gateway, and a COTS solution is thus not feasible. This includes in particular the TOLL Interface, the STAR Interface, TOLL transmitter (TTx), STAR receiver (SRx), the RRM subsystem and parts of the AAA functions. The division of work between the COTS products and the system specific features has been clearly identified, making it possible to integrate these two parts of the gateway in a seamless and consistent manner.

Services and Applications

The gateway integrates different capabilities of various applications to provide broadband access to individual subscribers, corporate users and ISP operators. Those applications include Internet access, Intranet Network, Videoconference, Broadcast and multicast multimedia, Transaction services and, of course, Telephony (more application detail please see Application Note).

Any applications that run on top of IP and are satisfied by the CoS/QoS can efficiently run over SG gateway platform.

System Overview

The IPSTAR system comprises of a gateway earth station communicating over a IPSTAR satellite to provide broadband packet-switched communications to a large number of small Terminals. Its network, physically, has a star configuration. The wide-band data traffic from the Gateway to the low-cost terminals are sent out in a Time Division Multiplex(TDM) platform over one or more Orthogonal Frequency Division Multiplexing(OFDM) channels. To get greater performance, these forward channels also use highly efficient transmission methods including Turbo Product Codes (TPCs) and higher order modulation (L-codes). In the terminal to Gateway direction or return link, the narrow-band channels using the same efficient transmission methods are multiplexed and carried by channels that operated in different types of multiple-access techniques based on bandwidth usage behavior. Those techniques include Slotted-ALOHA, TDMA, pre-assigned TDMA.

IPSTAR Gateway Components