Wireless Communication MCQ || Wireless Communication Questions and Answers

Answer.4. Modulation

Explanation

Equalization, diversity, and channel coding techniques are three independent techniques that are used separately or in combination to process the signal to improve received signal quality and link performance within small-scale time and distances. Three different effects are the main reasons for multi-path propagation. These are reflection, diffraction and scattering.

Answer.3. 300 Hz

Explanation

Interim Standard 95 (IS-95) is a second-generation (2G) mobile telecommunications standard based on code division multiple access (CDM technology, which guarantees multiple access when sending voice and data between mobile phones and cell sites. It is marketed under the brand name CDMA One (cdmaOne).

Answer.4. Outage event

Explanation

• In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors.
• The probability of outage is another means to judge the effectiveness of the signaling scheme in a mobile radio channel.
• An outage event is specified by a specific number of bit errors occurring in a given transmission. Bit error rates and probability of outage for various modulation schemes under various types of channel impairments can be evaluated either through analytical techniques or through simulations.
• While simple analytical techniques for computing bit error rates in slow flat-fading channels exist, performance evaluation in frequency selective channels and computation of outage probabilities are often made through computer simulations.

Answer.2. GSM

Explanation

• GSM stands for Global System for Mobile Communication. It is a digital cellular technology used for transmitting mobile voice and data services.
• GSM devised a combination of TDMA/FDMA as the method to divide the bandwidth among the users.
• 2G systems combined with general packet radio services (GPRS) are often described as 2.5G, that is, a technology between the 2G and third-generation (3G) of mobile systems.
• GSM (Global System for Mobile) is a TDMA standard for a 2G network. HSCSD (High-Speed Circuit-Switched Dat, GPRS (General Packet Radio Service) and EDGE (Enhanced Data rates for GSM Evolution) are TDMA standards of 2.5G technology.

Answer.2. Hopset

Explanation

• Frequency hopping (FH) communication is one of the main types of spread spectrum. communication. The carrier frequency of the FH signal hops under the control of a pseudo-noise. (PN) code, by which the spectrum is spread.
• It provides a very robust transmission path in the presence of interferences such as multipath, noise, and other wireless transmissions, etc. due to the support of wide bandwidth.
• It can be employed in point to multipoint applications.
• The set of possible carrier frequencies in FH-SS is called hopset.
• Hopping occurs of a frequency band that includes a number of channels. Each channel is defined as a spectral region with a central frequency in the hopset.

Answer.3. W-CDMA

Explanation

• The 3G evolution for GSM, IS-136, and PDC systems leads to W-CDMA (Wideband CDM.
• WCDMA (Wideband Code Division Multiple Access) UMTS standard for 3G digital mobile networks, using CDMA technology. It is the evolution path for GSM and EDGE to UMTS and offers increased voice capacity and theoretical peak data speeds of up to 2 Mbps.

Answer.2. Variable envelope

Explanation

• In Minimum-shift keying, bits are separated into even and odd bits, and each bit’s duration is doubled.
• Minimum shift keying, MSK offers advantages in terms of spectral efficiency when compared to other similar modes, and it also enables power amplifiers to operate in saturation enabling them to provide high levels of efficiency.
• MSK has a constant envelope. It is a spectrally efficient scheme. It possesses properties such as constant envelope, spectral efficiency, good BER performance, and self-synchronizing capability.

Answer.4. GPRS

Explanation

• CDMA2000 is a family of technology for 3G mobile cellular communications for transmission of voice, data, and signals. It supports mobile communications at speeds between 144Kbps and 2Mbps. It has a packet core network (PCN) for high-speed secured delivery of data packets.
• Cdma2000 is a 3G technology evolved from the IS-95 CDMA technique. WCDMA is a 3G technology that evolved from GSM technology.
• 3G Cdma2000 is based on the original IS-95 and IS-95A CDMA standards, as well as the 2.5G IS-95B air interface.
• While upgrading, Cdma2000 maintains backward compatibility with existing IS-95, IS-95A, and IS-95B equipment.
• Thus, Cdma2000 allows wireless carriers to introduce a family of new high data rate Internet access capabilities within existing systems.

Answer.4. FSK

Explanation

• Linear modulation is a scheme in which the baseband signal is linearly related to the modulated signal; that is, the modulated signal reflects a continuously variable range of values of the base-band signal. Linear modulation has very limited use in space systems.
• OQPSK, π/4 QPSK, and BPSK are the most popular linear modulation techniques. They have very good spectral efficiency. However, FSK is a non-linear modulation technique.