Aricent Technologies Technical Interviews Question Bank continued from Part 2
Q-11. What is TDMA and FDMA? Explain their difference.
A : TDMA refers to Time Division Multiple Access which is a channel multiplexing technique where users are assigned different time slots such that eight simultaneous calls can be made using the entire bandwidth. FDMA stands for Frequency Division Multiple Access which is also a channel multiplexing technique where users are assigned different frequency bands within which they can operate at any point of time.
Q-12. In which case is noise low – CDMA or GSM and why?
A : Noise is low in the case of CDMA because it uses orthogonal codes for different users which are non-overlapping so there is no interference due to other coded signals even if they overlap with the desired signal.
Q-13. What is transducer? Give an example.
A : Transducer is a device that converts any physical quantity into an electrical signal for example Cathode Ray Oscilloscope (CRO).
Q-14. What is transponder?
A : Transponder refers to TRANS-resPONDER which is a device that receives, amplifies, and then retransmits the (reply) signal to a different frequency upon proper verification of the received signal.
Q-15. What is handoff? Give a brief description about its types.
A : When a mobile user moves from one cell to another (i.e. changes its cell), earlier channels are required to be disconnected and new channels have to be allocated by the new cell. A process must be there to avoid call drop due to low minimum usable power of the Mobile Station. This process is called handoff or handover. There are two types of handoffs – Soft (in which new connection is established before disconnecting the previous one thus is more efficient but more costly, mostly used for cell phone calls) and Hard (in which connection from previous cell is disconnected before establishing a connection with the new cell. More affordable but is used for the services that can allow slight delays, such as mobile broad band internet).
Gautam Vashisht, JIIT Noida
Continued to Part 4