STEM help / Data dialogs

Service / Demand

In this dialog you describe the forecast demand in the market for the service, first in terms of the number of customers or connections, as a market penetration, and then the average load or traffic per customer or connection. Not all of the traffic inputs are required, depending on the type of service and the preferred formulation for calculating the results. The Distribution parameters allow the peak traffic to be inferred from the traffic volume, or vice versa; these contrasting approaches to the calculations are common choices for voice and data services, respectively. The pivotal Traffic Calculation input (see below) determines which inputs will drive the calculation, and which will be ignored.

Connections

Connections Unit

The unit of connections, e.g., Customers, Establishments, Homes. Either type a unit or choose from the drop-down list.

The selection has no mathematical effect on the model but the text is used to label the y-axis on results graphs.

Default: none.

Customer Base

The number of potential customers for a Service, e.g., the total number of businesses, the number of small, medium or large businesses or the adult population of an area.

The Customer Base for a Service can be defined directly as a time series, or as a reference to a separate Market Segment or Transformation element.

Default: Constant {0.0}.

Penetration

The proportion of a Service’s Customer Base taking up the service. This can be defined directly as a time series, or as a reference to a separate Transformation element.

Default: Constant {1.0}. All potential customers are connected.

Traffic Volume

Traffic Unit

The unit of traffic volume, e.g., Calls, Call Minutes, Mbit. Either type in a unit or choose from the drop-down list.

The selection has no mathematical effect on the model but the text is used to label the y-axis on results graphs.

Default: none.

Traffic per Connection

The average traffic that each connection generates in a Traffic Period. This can be defined directly as a time series, or as a reference to a separate Transformation element.

For a data service (i.e., with Traffic Calculation set to Peak Driven) this input is ignored.

Default: Constant {1.0}. Each connection generates one unit of traffic per year.

Traffic Period

Defines a reference period for the Traffic per Connection input (which is interpreted as traffic per traffic period, such as Call Minutes per month or archive GBytes per annum). This indicates how the traffic per connection input should then be scaled in proportion to the length of the current period for calculation.

Default: Year.

Distribution

Traffic Calculation

This pivotal input determines which inputs in this dialog will drive the calculations of results, and which will be ignored, as follows:

Volume Driven: the Busy Hour Traffic result is inferred from the (average) Traffic per Connection input, according to the stated Distribution parameters, and the Nominal Bandwidth per Connection and Contention Ratio inputs are ignored

Peak Driven: the Busy Hour Traffic result is calculated directly from the Nominal Bandwidth and Contention Ratio inputs, the Annual Traffic result is then inferred from the busy hour traffic, according to the stated Distribution parameters, and the Traffic per Connection input is ignored

Independent: used for some media services for which the peak traffic and traffic volume can be estimated directly without reference to the Distribution inputs which are ignored in this case.

In most cases, the Distribution parameters in this dialog allow the peak traffic to be inferred from the traffic volume, or vice versa; these contrasting approaches to the calculations are common choices for voice and data services, respectively.

Default: Volume Driven.

Busy Days per Year

The number of days in a year when there is significant traffic, used as part of the calculation of busy-hour traffic from traffic volume.

Default: Constant {250.0}. Assumes that there are 250 days per year when traffic is significant, based on 50 working weeks per year and 5 working days per week. 365 would be more appropriate for a domestic service.

Prop. Of Traffic in Busy Hour

The proportion of daily traffic that will be carried by a Service in the busy hour, used as part of the calculation of busy-hour traffic from annual traffic.

Default: Constant {0.2}. Assumes that 20% of the total daily traffic is carried during the busy hour.

Annual to Busy-Hour Unit Ratio

The number of Traffic Units per Busy Hour Traffic Unit per hour, used as part of the calculation of busy-hour traffic from traffic volume.

Default: 60.0. Assumes the Traffic Unit is Call Minutes and the Busy Hour Traffic Unit is Erlangs: there are 60 Call Minutes per hour. This ratio must be changed if different units are used.

For a data service, enter a ratio in accordance with the given annual and busy-hour traffic units. For example, if the Busy Hour Traffic Unit is Mbit/s and the Traffic Unit is GBytes, the conversion factor is 3600 (going from seconds to hours) divided by 8 (bits to bytes), divided by 1024 (MBytes to GBytes).

Busy Hour Traffic

Busy Hour Traffic Unit

The unit of busy-hour traffic, e.g., Erlangs, Mbit/s. Either type a unit or choose from the drop-down list.

The selection has no mathematical effect on the model, but the text is used to label the y-axis on results graphs.

Default: None.

Nominal Bandwidth per Connection

For a data service, the nominal bandwidth of each connection.

Default: Constant {0.00}.

Contention Ratio

For a data service, the ratio of the theoretical maximum demand to the demand that can be met by the network. For a voice service (i.e., with Traffic Calculation set to Volume Driven) this input is ignored.

Default: Constant {10.00}. Assumes that the network is dimensioned to meet one tenth of the theoretical maximum demand if all users required the service simultaneously.

 

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