2.2 FACTORS INFLUENCING THE CHOICE OF DIGITAL COMMUNICATION IN A NETWORK

Question 1

WHAT ARE THE FACTORS THAT STOP BITS FROM REACHING ITS DESTINATION WHEN DEVICES TRANSFER DATA?

Answer 1

• Transfer method
• Interference
• Blockages
• Distance

Question 2

WHAT ARE THE TWO TYPES OF TRANSFER METHODS?

Answer 2

Wired
Wireless

Question 3

FEATURES OF WIRED TRANSFER METHODS

Answer 3

• More bandwidth available
• Copper cables carry more frequencies - conducts electricity
• Cables are cheap if purchased for a smaller number of devices
• Risk of tripping over cables.
• Faster speed
• Less affected interference
• Not portable
• May need signal booster if connection is more than 100m long.
• More secure
• High maintenance - using wires for a while may damage them

Question 4

FEATURES OF WIRELESS TRANSFER METHODS

Answer 4

• Works on limited number of frequencies
• No need to buy cables
• May need wireless access point
• Slight radiation concern
• Slower speed
• Affected by interferences and obstacles
• Portable within a single range
• Tidy
• Less secure - easy to intercept using a wireless signal
• No maintenance required

Question 5

WHAT IS INTERFERENCE?

Answer 5

Other electromagnetic systems that interfere with wired and wireless systems. Interferences can be carried by signals from wireless devices/routers/appliances emitting electromagnetic fields.

Question 6

EXAMPLE OF DEVICES EMITTING ELECTROMAGNETIC FIELDS?

Answer 6

Fridges
Microwaves

Question 7

HOW ARE CABLED CONNECTIONS SHIELDED FROM INTERFERENCE?

Answer 7

Has wires wrapped with a thin layer of metal.

Question 8

WHAT ARE BLOCKAGES?

Answer 8

Walls and furniture that reduce strength of wireless signals.

Question 9

WHAT DO BLOCKAGES REDUCE?

Answer 9

Bandwidth

Question 10

HOW DOES DISTANCE AFFECT DIGITAL COMMUNICATION?

Answer 10

Strength of wired/wireless is reduced when distance increases.

Question 11

WHAT DOES THE SPEED OF DATA TRANSFER DEPEND ON?

Answer 11

Depends on the bandwidth of the connection.
Latency

Question 12

WHAT IS BANDWIDTH?

Answer 12

Number of bits that can be carried by a connection in one second.

Question 13

WHAT IS LATENCY?

Answer 13

Latency is the amount of time taken to send data between devices.

Question 14

WHAT DOES HIGHER BANDWIDTH MEAN?

Answer 14

Faster uploads and downloads. More data can be transferred every second. Large data can be transferred in a short time.

Question 15

WHAT DOES LOWER LATENCY MEAN?

Answer 15

Smoother gaming and streaming.

Question 16

EXAMPLES OF IMPACTS ON USER EXPERIENCE?

Answer 16

• Games - HIGH BANDWIDTH = Smooth gameplay. HIGH LATENCY = Lag, unresponsive.
• TV - HIGH LATENCY = Delay in real-time events. Delay in videos being recieved.

Question 17

WHAT IS A BROADBAND?

Answer 17

Provides fast access to internet through connection to ISP.

Question 18

WHAT IS ISP?

Answer 18

Internet Service Provider. Provides access to internet fiber optic cable.

Question 19

HOW DO INTERNET FIBER OPTIC CABLES WORK?

Answer 19

Sends data using light signals. Copper cables that send data through electrical signals are conducted through copper wires.

Question 20

WHAT IS A MOBILE BROADBAND?

Answer 20

Provides high speed wireless. Connectivity using 3G/4G technology. Connect using a mobile phone network - acting as the users ISP.

Question 21

WHAT IS A BUFFER?

Answer 21

Area of memory used to temporarily store data, used when streaming videos.

Question 22

HOW DOES A BUFFER WORK WHEN STREAMING A VIDEO?

Answer 22

• Portion of video data is stored temporarily in buffer. Video will not start when there is enough data in buffer to play a few seconds of the video. When the seconds are playing, more data is downloaded to continue filling buffer.
• If buffer is empty, there is no more video to play and pauses until more data is downloaded.
• To avoid this, data must be constantly downloaded (filling it faster than emptying)