(2)Billing methods
“Billing” refers to the process of charging fees for the use of services.
There are various billing methods including flat, metered, and base plus
metered.
Billing
method
Reference
Transmission speed
The “transmission speed” indicates the
amount of data that can be transferred
within a specific time. It is expressed in
units such as “bps (bits per second)” or
“B/s,” which is the amount of data that
can be transmitted in one second.
Fee structure
Flat
Usage fees are always billed at a flat rate regardless of the length of
usage, such a “flat 1,000 yen monthly fee.”
Metered
Billed according to the length of usage such as “10 yen per three minutes.”
Base plus
metered
Billed at a base fee plus additional metered charges, with the additional charges covering usage that exceeds the amount covered by the
base fee.
Cap
Capped at a maximum fee such as “10 yen per three minutes up to
one hour, not over 1,000 yen per month regardless of usage.”
●Calculation of transmission time/communications fee
The “transmission time” refers to the time required to transmit data. The
following formula can be used to calculate the transmission time, and the
communications fee for the transmission time.
Formula for calculating transmission time
Transmitted data ÷ (Line transmission speed × Transmission efficiency)
Reference
Transmission efficiency
Example 1
The “transmission efficiency” is the percentage of actual data that is contained
within all the transmitted data. Due to
the inclusion of other data such as control codes, the transmission efficiency
normally ranges from 60 to 80%.
Approximately how many minutes are required to transmit data
under the following conditions?
Transmission data
: 2000 × 1,500 pixel JPEG image, 16.77 million colors, compressed to one-tenth size
Line speed
: 33.6kbps modem
Transmission efficiency : 60%
① Calculation of transmission data volume
2000 pixels × 1500 pixels × 24 bits per dot
(16.77 million
(Total pixels)
colors is 224)
1
10
(Compression rate)
×
= 7,200,000 bits
② Calculation of transmission time
7,200,000 bits ÷ (33,600 bits per second × 60%)
(Line transmission speed) (Transmission
(Transmission
data volume)
efficiency)
≒ 357 seconds ≒ 6 minutes
Therefore, approximately six minutes are needed to transmit the data.
277