VSAT Designs

Satellite Network Topology

Satellite sites can be interconnected in 3 different ways each topology with its application advantages or purposes.  The network sites may connect in a Star, Meshed or Hybrid topology. The Meshed topology allows direct communications from any site to any site while the Star option depends on a central site to which every branch site connect.

myiQ has engineering teams experienced in the implementation and support of VSAT dish terminlas in the challenging circumstances of Africa. We connect organizations throughout Europe, Middle East and Africa as well as other parts of the world.

Star Topology

All messages converge to a central site. There is no direct communication between the difference sites. Not suitable for voice between the different sites.

Mesh Topology

Ideal for voice and data when direct communication from any site to any site in the network is required

Hybrid Topology

Hybrid is a combination of the Star and Mesh topologies. Hybrid can't do anything that mesh cannot do. The reason for going hybrid is a tradeoff with cost.  Parts of the network might need mesh and other sites might only need to talk to one central site thus connecting with a Star topology

Satellite Access Topologies

Are the features of different software to access the networked sites.

• TDM (Time Division Multiplex) or DVB (Digital Video Broadcaster): Used in the STAR topology. Slow response, collision rate of 80% (loss of throughput), double hop, cannot be meshed and it has a management system.
• SCPC (Single Channel Per Carrier): Suitable for 2 sites to communicate to each other. The Star and Mesh topologies can be emulated if a modem for each site is stacked in each site but it will be an expensive and cumbersome solution to achieve the same and it does not provide a management system.
• TDMA (Time Division Multiplex Access): Fully meshed, network management, frame relay, voice and data. The more flexible and manageable solution.
• DAMA (Demand Assigned Multiple Access): A technique to use bandwidth when required only and applicable to voice. When a telephone dials a call, a control center allocates bandwidth to the call and the bandwidth is thereafter voice activated. Data can be transmitted as done over a dial up telephone line. However the voice activation and deactivation of the bandwidth results in poor quality and slow transmission.
• DVB (Digital Video Broadcaster): It is attractive to use DBV with C Band for the “down” transmission of Internet. The pages requested are sent to the Internet through the C Band network and the download from the Internet is transmitted through the DBV. The advantage of using a combination of the two VSAT technologies is the much lower cost of DVB and the fact that the C Band, more expensive, is free for the transmission of critical data.

Satellite Frequency

Determines, amongst other, the footprint covered on Earth and the quality of the signal.

• C Band: Low frequency, large foot print (recommended when sites to be networked are far apart), large dish and least expensive equipment but more expensive dish. The lower frequencies used by C Band perform better under adverse weather conditions (including rain) than the Ku band or Ka band frequencies.
• Ku Band: Medium frequency, medium foot print, medium dish, affected by rain (as the snow seen on TV), stronger signal and more sophisticated and expensive equipment though cheaper dish. The most common Ku band digital reception format is DVB (Digital Video Broadcaster).
• Ka Band: High frequency, small foot print, small dish, highly affected by rain, strongest signal, highly sophisticate and expensive equipment though the cheapest dish. Ka band dishes can be much smaller than C band dishes. Ka band dishes vary from 2' to 5' in diameter. Ka band satellites typically transmit with much more power than C band satellites. The higher frequencies of Ka band are significantly more vulnerable to signal quality problems caused by rainfall, known as rainfade.

We offer dedicated frequencies when advisable for the envisaged customer applications. Our solutions deliver the most effective satellite connectivity within VSAT technologies.

Networks and Bandwidth

Applied to Satellite, Radio and Terrestrial networks, it is the capacity of the "pipe" transporting the messages from site to site (voice and/or data). It is the amount of traffic that is allowed to occur from one network point and the rest of the network per second.

Dedicated Bandwidth:

The bandwidth is dedicated to a service, application, site or customer. Network operators refer to dedicated bandwidth as not shared by other customers.

Shared Bandwidth:

The bandwidth can be dedicated to a customer and within the customer organization shared by different sites, services and applications or the bandwidth can be shared by a number of customers of the network operator.

Sharing with other customers of the network operator reduces costs but is not advisable for applications that required fast and consistent response times.

We allocate and guarantee a minimum bandwidth to each service, application, site or customer. These bandwidth are then placed in a pool and available to every service, application, site or customer when not in use. It is practically impossible that every user is accessing data at the same time and instance and therefore users end up having more bandwidth than that contracted for.

However at peak times when most users are accessing data the extra bandwidth is not available and the systems will slow down as opposed at off-peak times. It is not advisable for applications that required fast and consistent response times.