Technologies

Advantages

Disadvantages

Accuracy

Ultrasound

-Simple and cheap equipment

-Precision measurement possibilities

-The necessity of the establishment of the recipients in every room

-Negative influence a high density-tone

-A few centimeters when it is placed frequent enough

RFID

-The transmitter and receiver don’t need to see each other directly.

-Opportunity to work in all types of environments

-Fast interactions

-Passive tags have low precision than active tags.

-RFID Readers are expensive

1 - 10 meters (extendable)

Bluetooth

-Any kind of Bluetooth device can be monitored (cell phone, mp3 player etc.)

-Variable reading distance (1 m vicinity)

-Cost effective for large scale installation

-Limited bandwidth

-Transmission delay.

-The possibly of a maximum of seven sub-links corresponds to main connection

2 - 10 meters

WLAN (Wi-Fi)

-The possibility of use the infrastructure of IEEE 802.11

-Low cost

-Poor performance for multilayered and very dense areas.

-Due to signal reflection and dynamic network structure variable signal strength.

1 - 3 meters (in range of 50 meters)

Infrared

-Compact

-Low power consumption

-Sensitive to daylight

-Receiver and transmitter needs to see each other directly

5 - 10 meters