The Uncontended Option

Over the years, a divide has developed between the two primary networks used in designing communications solutions. Single channel per carrier (SCPC) networks assign users with a single signal at a given frequency and bandwidth. Time division multiple access (TDMA) networks differ from SCPC in that multiple users can share the same frequency channel by dividing the signal into different time slots.

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Service providers have historically deployed a TDMA network as a contended service with a guaranteed committed information rate (CIR). This contention rate may be as low as four-to-one or as high as 100-to-one. The contention ratio is the ratio of the potential maximum demand to the actual bandwidth. The higher the contention ratio, the greater the number of users trying to access the actual bandwidth at any one time and therefore lowers the effective bandwidth offered. As such, TDMA became known as the “shared” network while SCPC became referred to as the “dedicated” network.

What many customers don’t know, though, is that service providers have the ability to offer uncontended TDMA networks with a dedicated CIR. Under this network model, an uncontended CIR is like a dedicated lane on the freeway that can only be used by a single company, allowing the company to send any mix of cars, vans and trucks they like. The dedicated lane is unaffected by rush hour, or activity in other lanes.

As a matter of fact, TDMA networks are able to react to changing traffic requirements from the VSAT to the hub much faster than an SCPC network. This makes a TDMA network much more appealing when dealing with bursty traffic. TDMA also allows for a Maximum Information Rate (MIR) to be incorporated into the SLA. In the event a very large file needs to be transmitted, the bursting capability may exceed a customer’s CIR if the bandwidth is available.

With highly mobile assets that need to move from one region of the world to the next, TDMA networks are much more flexible in supporting those migrations which is a key factor in the complexity of offshore communications.merchant vessel-017272-edited.jpg

While TDMA networks are capable of delivering network speeds up to 20 megabits per second (Mbps) up and 10 Mbps down, which likely covers the majority of connectivity requirements, we’re aware that there are some instances where SCPC is the more suitable network due to very high bandwidth demands combined with lower latency.

At the end of the day, a service provider should be able to determine the network that makes the most sense for your communications needs. We need to remove the biases that have grown over the years and recognize that when it comes to delivering quality communications, there is a TDMA option that can stand up to the reliability of SCPC.

Topics: Solutions