27-08-2012, 05:14 PM
Infra red vs radio transmission
[attachment=32868]
One technology is based on the transmission of infra red light (e.g., at 900 nm
wavelength), radio transmission (e.g., 2.4 GHz in the license-free ISM band).
● The main advantages of infra red technology are its simple and extremely
cheap senders and receivers which are integrated into nearly all mobile
devices available today. No licenses are needed for infra red
technology and shielding is very simple. Electrical devices do not interfere
with infra red transmission.
● Disadvantages of infra red transmission are its low bandwidth compared to
other LAN technologies. However, their main disadvantage is that infra red
is quite easily shielded. Infra red transmission cannot penetrate walls or
other obstacles. Typically, for good transmission quality and high data rates
a LOS, i.e., direct connection, is needed.
Radio waves for data transmission,
● Advantages of radio transmission include the long-term experiences made
with radio transmission for wide area networks (e.g., microwave links) and
mobile cellular phones. Radio transmission can cover larger areas and can
penetrate (thinner) walls, furniture, plants etc. Additional coverage is
gained by reflection. Radio typically does not need a LOS if the frequencies
are not too high. Furthermore, current radio-based products offer much
higher transmission rates (e.g., 54 Mbit/s) than infra red (directed laser
links, which offer data rates well above 100 Mbit/s. These are not considered
here as it is very difficult to use them with mobile devices).
● Again, the main advantage is also a big disadvantage of radio transmission.
Shielding is not so simple. Radio transmission can interfere with other
senders, or electrical devices can destroy data transmitted via radio.
Additionally, radio transmission is only permitted in certain frequency
bands. Very limited ranges of license-free bands are available worldwide and
those that are available are not the same in all countries.
[attachment=32868]
One technology is based on the transmission of infra red light (e.g., at 900 nm
wavelength), radio transmission (e.g., 2.4 GHz in the license-free ISM band).
● The main advantages of infra red technology are its simple and extremely
cheap senders and receivers which are integrated into nearly all mobile
devices available today. No licenses are needed for infra red
technology and shielding is very simple. Electrical devices do not interfere
with infra red transmission.
● Disadvantages of infra red transmission are its low bandwidth compared to
other LAN technologies. However, their main disadvantage is that infra red
is quite easily shielded. Infra red transmission cannot penetrate walls or
other obstacles. Typically, for good transmission quality and high data rates
a LOS, i.e., direct connection, is needed.
Radio waves for data transmission,
● Advantages of radio transmission include the long-term experiences made
with radio transmission for wide area networks (e.g., microwave links) and
mobile cellular phones. Radio transmission can cover larger areas and can
penetrate (thinner) walls, furniture, plants etc. Additional coverage is
gained by reflection. Radio typically does not need a LOS if the frequencies
are not too high. Furthermore, current radio-based products offer much
higher transmission rates (e.g., 54 Mbit/s) than infra red (directed laser
links, which offer data rates well above 100 Mbit/s. These are not considered
here as it is very difficult to use them with mobile devices).
● Again, the main advantage is also a big disadvantage of radio transmission.
Shielding is not so simple. Radio transmission can interfere with other
senders, or electrical devices can destroy data transmitted via radio.
Additionally, radio transmission is only permitted in certain frequency
bands. Very limited ranges of license-free bands are available worldwide and
those that are available are not the same in all countries.