»Dual-Gateway

UHP Dual-Gateway™: Optimum Solution for Hierarchical VSAT Networks
Highlights:
  • Hierarchical topologies
  • Minimum latency
  • Cost-efficient terminals
  • High bandwidth efficiency
  • Low cost of network ownership
Description

VSAT networks are widely used for connectivity of remote offices with central infrastructure, including IP backbone. One of the challenges facing VSAT operators is how to design a satellite network with multiple layers of hierarchy. Enterprise networks comprise central and regional control offices, which must be connected to local branch offices via satellite links. In SCADA networks, regional offices use centralized backup. In cellular backhaul over satellite, there may be a requirement to direct some of the traffic locally, while the rest of the traffic is routed to a central gateway.

While it is possible to implement hierarchical networks with the help of standard Star (Hub-Spoke) network topology, such implementation will inevitably include double satellite hops between the regional offices and the local remote terminals (branch offices). In many applications, avoiding double satellite hop for local traffic is critical in order to minimize latency of voice calls and to eliminate double bandwidth allocation, especially for bandwidth-hungry video calls and large data transfers. One way of solving this problem is to use the Mesh feature in TDMA or TDM/TDMA networks, whereby single-hop links between regional offices and local terminals are established via one or more Mesh TDMA carriers.  Mesh TDMA has been an intrinsic feature of the UHP technology from its inception, with many of the UHP customers using it in hierarchical VSAT networks. At the same time, the Mesh approach has its limitations. First, the remote terminal equipment becomes significantly more expensive since it requires mesh routers and PLL LNB. Second, the outbound traffic (regional to local offices) in the sub-network adds to the size of the Mesh carrier and further increases the equipment cost at local offices.

The innovative technology UHP Dual-Gateway™ provides optimum solution for hierarchical networks and makes it possible to design such networks with single-hop connectivity using low-cost VSAT terminals and low-cost Regional Gateways (RGW). The Central Gateway (CGW) has a UHP TDM/TDMA Hub with at least one DVB carrier (TDM) and several TDMA return carriers. The Regional Gateway (RGW) also transmits a DVB (TDM) carrier and is capable of receiving one or more TDMA carriers.

UHP remote routers can simultaneously receive two TDM carriers from both Gateways (CGW and RGW), whereas each carrier can use its own MODCOD all the way to 32APSK. These two carriers provide single-hop connections from CGW and RGW to each remote terminal. In the return link, TDMA bursts transmitted by a given remote can be received by CGW and/or RGW, hence the connection is also single-hop. If required (when a remote terminal needs to transmit a high amount of traffic via a high-speed channel with a throughput of tens of Mbps), the remote terminal can also transmit its own DVB carrier (SCPC or MCPC) which can be received by CGW and RGW.

The Central Gateway (CGW) with its sophisticated Network Management System (NMS) is responsible for network control, which includes station access, timing, and resource assignment. Number of Regional Gateways (RGW) in the network is unlimited. Each remote is at all times connected with CGW and one RGW. UHP Dual-Gateway™ network employs standard UHP router models UHP-100 and/or UHP-200 with low-cost DRO LNB. Each of the remote routers has the dual DVB receiver option activated. CGW is a regular UHP TDM/TDMA Hub without any additional hardware or software options. RGW is implemented using another standard UHP product: dual router UHP-240, whereby one router is transmitting the DVB (TDM) Overlay carrier and the other is configured in TDM/TDMA Mesh mode in order to receive bursts from the local terminals. CGW treats RGW in the network as remote terminals, and has single-hop connectivity with all of them. If required, some or all RGW can also be connected with single-hop links via TDMA or DVB (TDM) Overlay.

Equipment cost for a VSAT hierarchical network with UHP Dual-Gateway™ architecture is comparable with that of a classic VSAT Star network. At the same time, UHP Dual-Gateway™ delivers superior value: single-hop connectivity in the regional sub-networks reduces latency and saves bandwidth by eliminating double bandwidth allocation.

Total Cost of Ownership (TCO) for UHP Dual-Gateway™ network is more than 40% lower than for a comparable Mesh TDMA network. Compared to Mesh, UHP Dual-Gateway™ also has a much lower cost of equipment (CAPEX). Besides, the software-defined architecture of the UHP products ensured that UHP Dual-Gateway™ network can be reconfigured to support Star and TDMA Mesh topologies without changing the equipment.

Since 2005 UHP Networks and the Romantis Group have been bringing disruptive innovation to the VSAT industry. The UHP product line is known for a number of industry firsts: from software defined remote, which achieves 8 times higher processing power per cubic inch than the nearest competitor, to the most versatile and lowest-cost Hub infrastructure with geographical redundancy. The time has come to revolutionize the design of hierarchical VSAT networks, radically improving their performance while at the same time making those networks more affordable. UHP Dual-Gateway™ is one major step in that direction.