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BlueTooth Interview Questions Answers

Question 1 : Give a generic description of Bluetooth?

Answer 1 : Bluetooth is a low-cost, short-range (RF) links between mobile PCs, mobile phones and other portable devices. Bluetooth can transmit through solid, non-metal objects.

Question 2 : How does Bluetooth use frequency hopping for security?

Answer 2 : Bluetooth picks a random frequency out of 79 and then hops around the range about 1600 times per second.

Question 3 : How many devices can communicate concurrently?

Answer 3 : A Bluetooth device playing the role of the “master” can communicate with up to 7 devices playing the role of the “slave”. This network of “group of up to 8 devices” (1 master + 7 slaves) is called a piconet. A piconet is an ad-hoc computer network of devices using Bluetooth technology protocols to allow one master device to interconnect with up to seven active slave devices (because a three-bit MAC address is used). Up to 255 further slave devices can be inactive, or parked, which the master device can bring into active status at any time.

Question 4 : How many SCO links are there in a piconet?

Answer 4 : In a piconet, there can be up to three SCO links of 64,000 bits per second each.

Question 5 : How secure a Bluetooth device is?

Answer 5 : Bluetooth uses the SAFER+ algorithm for authentication and key generation. The E0 stream cipher is used for encrypting packets. This makes eavesdropping on Bluetooth-enabled devices more difficult.

Question 6 : What are Bluetooth profiles?

Answer 6 : A profile is a description of how to use a specification to implement a particular function. The International Standards Organization (ISO) first came up with the idea of profiles. In Bluetooth, there are several profiles available and they are arranged in a hierarchical fashion. For example, in order to use the headset profile, a device must also include the lower level profiles such as the serial port and general access profiles.

Question 7 : What are Different Classes in Bluetooth?

Answer 7 : Bluetooth is a radio standard and communications protocol primarily designed for low power consumption, with a short range (power class dependent: 1 meter, 10 meters, 100 meters) based around low-cost transceiver microchip in each device. Bluetooth lets these devices communicate with each other when they are in range. The devices use a radio communications system, so they do not have to be in line of sight of each other, and can even be in other rooms, so long as the received power is high enough.

Question 8 : What are some of the uses of Bluetooth?

Answer 8 : Depending on the Bluetooth profiles included on the device, Bluetooth technology has the capability to wirelessly synchronize and transfer data among devices. The Bluetooth audio capabilities can be used for headset and hands free applications. The exact functionality provided by a Bluetooth enabled device depends on the Bluetooth profiles included.

Question 9 : What are the other (competing or not) wireless technologies?

Answer 9 : Wi-Fi, IrDa, EDGE, UWB (Ultra Wide Band)

Question 10 : What are the problems with older versions (1.0 and 1.0 B)?

Answer 10 : Versions 1.0 and 1.0 B had numerous problems and the various manufacturers had great difficulties in making their products interoperable. 1.0 and 1.0B also had mandatory Bluetooth Hardware Device Address (BD_ADDR) transmission in the handshaking process, rendering anonymity impossible at a protocol level, which was a major setback for services planned to be used in Bluetooth environments, such as Consumerism.

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