GCSEComputer ScienceEdexcelRevision Notes4. NetworksNetworksNetwork Speeds

Network Speeds (Edexcel GCSE Computer Science)

Revision Note

Robert Hampton

Written by: Robert Hampton

Reviewed by: James Woodhouse

Network Speeds

What is network speed?

  • Network speed is the amount of data that can be transferred across a network in 1 second

  • The higher the network speed, the more data can be transferred, and in less time

  • Network speed is measured in bits per second (bps)

Network speed

Written as

Equivalent to

1 kilobit per second

1 Kbps

1000 bps

1 megabit per second

1 Mbps

1000 Kbps
OR

1,000,000 bps

1 gigabit per second

1 Gbps

1000 Mbps
OR
1,000,000 Kbps

OR

1,000,000,000 bps

File Size, Transmission Rate & Time

  • You can calculate the amount of time it would take to transfer data across a network using the file size and transmission rate

What is transmission rate?

  • Transmission rate is the speed at which data is transferring across a network at that given moment in time

  • Transmission rate is measured in bits per second (bps)

  • Transmission rate is closely linked with network speed but with a subtle difference:

    • Transmission rate = given moment in time, can fluctuate

    • Network speed = fixed value, maximum rate (that you pay for)

Examiner Tips and Tricks

Remember that file size uses the binary (base-2) multiples and network speeds/transmission rates use the denary (base-10) multiples, this means that:

File size
1 KiB = 1024 bytes
1024 x 8 = 8,192 bits

Network speed/transmission rate
1 Kbps = 1000 bps (not 1024!)

  • File sizes are covered in more detail here

How do you calculate amount of time?

  • To calculate the amount of time to transfer data across a network, use the formula:

    • Time = size of file (bits) / network speed (bits)

Examiner Tips and Tricks

In the exam you are only expected to be able to construct expressions involving file size, transmission rate/network speed and time

You DO NOT have to carry out any calculations!

Example

"Construct an expression to show how many seconds it would take to transfer 750 KiB of data on a network with a speed of 5 Mbps"

  • Step 1 - convert file size to bits

File size

Expression

750 KiB

750 x 1024 x 8

(KiB > Bytes > Bits)

  • Step 2 - convert network speed to bits

Network speed

Expression

5 Mbps

5 x 1,000,000
(Mbps > bps)

  • Step 3 - Construct expression


    fraction numerator b i t s space t o space t r a n s f e r space open parentheses f i l e space s i z e close parentheses over denominator b i t s space p e r space s e c o n d space open parentheses n e t w o r k space s p e e d close parentheses end fractionfraction numerator 750 space x space 1024 space x space 8 over denominator 5 space x space 1000000 end fraction

Worked Example

Construct an expression to show how many seconds it will take to transmit 35 MiB of data using a network transmission speed of 1.5 Mbps.

You do not have to do the calculation [4]

Answer

  • File size

    • 35 x 1024 x 1024 [1]

    • x 8 [1]

  • Network speed

    • 1.5 x 1000000 [1]

  • Numerator/denominator

fraction numerator b i t s space t o space t r a n s f e r over denominator b i t s space p e r space s e c o n d end fraction [1]

  • e.g. :

fraction numerator 35 space x space 1024 space x space 1024 space x space 8 over denominator 1.5 space x space 1000000 end fraction

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    Author
    Reviewer
    Robert Hampton

    Author: Robert Hampton

    Expertise: Computer Science Content Creator

    Rob has over 16 years' experience teaching Computer Science and ICT at KS3 & GCSE levels. Rob has demonstrated strong leadership as Head of Department since 2012 and previously supported teacher development as a Specialist Leader of Education, empowering departments to excel in Computer Science. Beyond his tech expertise, Robert embraces the virtual world as an avid gamer, conquering digital battlefields when he's not coding.

    James Woodhouse

    Author: James Woodhouse

    Expertise: Computer Science

    James graduated from the University of Sunderland with a degree in ICT and Computing education. He has over 14 years of experience both teaching and leading in Computer Science, specialising in teaching GCSE and A-level. James has held various leadership roles, including Head of Computer Science and coordinator positions for Key Stage 3 and Key Stage 4. James has a keen interest in networking security and technologies aimed at preventing security breaches.