Below are some important Bluetooth interview questions which are asked in most MNC company interviews for beginners or professionals.
21. What is the data throughput speed of a Bluetooth connection?
Bluetooth transfers data at a rate of 721 Kbps, which is from three to eight times the average speed of parallel and serial ports, respectively. This bandwidth is capable of transmitting voice, data, video and still images
22. Will Bluetooth and Wireless LAN (WLAN) interfere with each other?
No, both Bluetooth and WLAN can co-exist. Since Bluetooth devices use Frequency Hopping and most WLANs use Direct Sequence Spreading techniques they each appear as background noise to the other and should not cause any perceivable performance issues.
23. Will other RF (Radio Frequency) devices interfere with Bluetooth Devices?
No. Bluetooth radios operate on the unlicensed 2.4 GHz (Industrial, Scientific and Medical) frequency band that is shared among other devices (microwave ovens, cordless phones, garage door openers, etc. ). Bluetooth radios switch frequencies at such a rapid pace (1,600 times per second) and the data packets are so small that interference from other RF sources is highly unlikely. Bluetooth is a robust communication system.
24. What is Frequency-Hopping Spread Spectrum (FHSS)?
Frequency-Hopping Spread-Spectrum (FHSS) is a spread spectrum modulation scheme that uses a narrowband carrier that changes frequency in a pattern known to both transmitter and receiver. Properly synchronized, they maintain a single logical channel. To an unintended receiver, FHSS appears as short-duration impulse noise. More simply, the data is broken down into packets and transmitted to the receiver of other devices over numerous “hop frequencies” (79 total) in a pseudo random pattern. Only transmitters and receivers that are synchronized on the same hop frequency pattern will have access to the transmitted data. The transmitter switches hop frequencies 1,600 times per second to assure a high degree of data security
25. How secure is a Bluetooth network?
Bluetooth is extremely secure in that it employs several layers of data encryption and user authentication measures. Bluetooth devices use a combination of the Personal Identification Number (PIN) and a Bluetooth address to identify other Bluetooth devices. Data encryption (i.e., 128-bit) can be used to further enhance the degree of Bluetooth security. The transmission scheme (FHSS) provides another level of security in itself. Instead of transmitting over one frequency within the 2.4 GHz band, Bluetooth radios use a fast frequency-hopping spread spectrum (FHSS) technique, allowing only synchronized receivers to access the transmitted data
26. What is the future direction of the Bluetooth standard?
At this time, we anticipate the Bluetooth SIG to evolve the Bluetooth technology to provide greater bandwidth and distances, thus increasing the potential platforms and applications used in the emerging personal area networking marketplace.
27. How is Bluetooth used?
Bluetooth can be used to wirelessly synchronize and transfer data among devices. Bluetooth can be thought of as a cable replacement technology. Typical uses include automatically synchronizing contact and calendar information among desktop, notebook and palmtop computers without connecting cables. Bluetooth can also be used to access a network or the Internet with a notebook computer by connecting wirelessly to a cellular phone.
28. Do you Know about OBEX Protocol?
IrOBEX (shortly OBEX) is a session protocol developed by the Infrared Data Association (IrDA) to exchange objects in a simple and spontaneous manner. OBEX, which provides the same basic functionality as HTTP but in a much lighter fashion, uses a client-server model and is independent of the transport mechanism and transport API, provided it realizes a reliable transport base. Along with the protocol itself, the “grammar” for OBEX conversations between devices, OBEX also provides a model for representing objects and operations. In addition, the OBEX protocol defines a folder-listing object, which is used to browse the contents of folders on remote device. In the first phase, RFCOMM is used as sole transport layer for OBEX.
29. What is Service Discovery Protocol?
Discovery services are crucial part of the Bluetooth framework. These services provide the basis for all the usage models. Using SDP, device information, services and the characteristics of the services can be queried and after that, a connection between two or more Bluetooth devices can be established. SDP is defined in the Service Discovery Protocol specification.
30. What is Link Manager Protocol?
The link manager protocol is responsible for link set-up between Bluetooth devices. This includes setting up of security functions like authentication and encryption by generating, exchanging and checking of link and encryption keys and the control and negotiation of baseband packet sizes. Furthermore it controls the power modes and duty cycles of the Bluetooth radio device, and the connection states of a Bluetooth unit in a piconet.
21. What is the data throughput speed of a Bluetooth connection?
Bluetooth transfers data at a rate of 721 Kbps, which is from three to eight times the average speed of parallel and serial ports, respectively. This bandwidth is capable of transmitting voice, data, video and still images
22. Will Bluetooth and Wireless LAN (WLAN) interfere with each other?
No, both Bluetooth and WLAN can co-exist. Since Bluetooth devices use Frequency Hopping and most WLANs use Direct Sequence Spreading techniques they each appear as background noise to the other and should not cause any perceivable performance issues.
23. Will other RF (Radio Frequency) devices interfere with Bluetooth Devices?
No. Bluetooth radios operate on the unlicensed 2.4 GHz (Industrial, Scientific and Medical) frequency band that is shared among other devices (microwave ovens, cordless phones, garage door openers, etc. ). Bluetooth radios switch frequencies at such a rapid pace (1,600 times per second) and the data packets are so small that interference from other RF sources is highly unlikely. Bluetooth is a robust communication system.
24. What is Frequency-Hopping Spread Spectrum (FHSS)?
Frequency-Hopping Spread-Spectrum (FHSS) is a spread spectrum modulation scheme that uses a narrowband carrier that changes frequency in a pattern known to both transmitter and receiver. Properly synchronized, they maintain a single logical channel. To an unintended receiver, FHSS appears as short-duration impulse noise. More simply, the data is broken down into packets and transmitted to the receiver of other devices over numerous “hop frequencies” (79 total) in a pseudo random pattern. Only transmitters and receivers that are synchronized on the same hop frequency pattern will have access to the transmitted data. The transmitter switches hop frequencies 1,600 times per second to assure a high degree of data security
25. How secure is a Bluetooth network?
Bluetooth is extremely secure in that it employs several layers of data encryption and user authentication measures. Bluetooth devices use a combination of the Personal Identification Number (PIN) and a Bluetooth address to identify other Bluetooth devices. Data encryption (i.e., 128-bit) can be used to further enhance the degree of Bluetooth security. The transmission scheme (FHSS) provides another level of security in itself. Instead of transmitting over one frequency within the 2.4 GHz band, Bluetooth radios use a fast frequency-hopping spread spectrum (FHSS) technique, allowing only synchronized receivers to access the transmitted data
26. What is the future direction of the Bluetooth standard?
At this time, we anticipate the Bluetooth SIG to evolve the Bluetooth technology to provide greater bandwidth and distances, thus increasing the potential platforms and applications used in the emerging personal area networking marketplace.
27. How is Bluetooth used?
Bluetooth can be used to wirelessly synchronize and transfer data among devices. Bluetooth can be thought of as a cable replacement technology. Typical uses include automatically synchronizing contact and calendar information among desktop, notebook and palmtop computers without connecting cables. Bluetooth can also be used to access a network or the Internet with a notebook computer by connecting wirelessly to a cellular phone.
28. Do you Know about OBEX Protocol?
IrOBEX (shortly OBEX) is a session protocol developed by the Infrared Data Association (IrDA) to exchange objects in a simple and spontaneous manner. OBEX, which provides the same basic functionality as HTTP but in a much lighter fashion, uses a client-server model and is independent of the transport mechanism and transport API, provided it realizes a reliable transport base. Along with the protocol itself, the “grammar” for OBEX conversations between devices, OBEX also provides a model for representing objects and operations. In addition, the OBEX protocol defines a folder-listing object, which is used to browse the contents of folders on remote device. In the first phase, RFCOMM is used as sole transport layer for OBEX.
29. What is Service Discovery Protocol?
Discovery services are crucial part of the Bluetooth framework. These services provide the basis for all the usage models. Using SDP, device information, services and the characteristics of the services can be queried and after that, a connection between two or more Bluetooth devices can be established. SDP is defined in the Service Discovery Protocol specification.
30. What is Link Manager Protocol?
The link manager protocol is responsible for link set-up between Bluetooth devices. This includes setting up of security functions like authentication and encryption by generating, exchanging and checking of link and encryption keys and the control and negotiation of baseband packet sizes. Furthermore it controls the power modes and duty cycles of the Bluetooth radio device, and the connection states of a Bluetooth unit in a piconet.
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