1. In LTE network architecture, the interface between the internet and PDN gateway is:
Um
SS7
S5
SGi
Answer.4. SGi
Explanation
In LTE network architecture, the interface between the internet and PDN gateway is SGi.
1. The SGi interface connects the PGW to an external network (PDN), and the Gi interface connects the GGSN to an external network (PDN).
2. The interface is based on the IP packet (user data/payload/data plane), possibly also enabling the exchange of signaling (ex. OSPF, BGP, etc.). The interface can connect to the Radius server if Remote Access Dial-In User Service (Radius) is used.
3. The functions of the SGi interface include access to the Internet, Intranet, or an ISP (Internet service provider) and involve functions such as IPv4 address allocation, IPv6 address autoconfiguration, and may also involve specific functions such as authentication, authorization, and secure tunneling to the intranet/ISP.
4. The implementation Gi, SGi Interface in a real topology network. All IP various packets combine in one routing table (virtual-router or routing-instance).
2. What is Mobile communication?
Allows to communicate from different locations without the use of physical medium
Allows to communicate from different locations with the use of physical medium
Allows to communicate from same locations without the use of physical medium
Allows to communicate from same locations with the use of physical medium
Answer.1. Allows to communicate from different locations without the use of the physical medium
Explanation
Mobile communication is talking, texting, or sending data or image files over a wireless network. Mobile Communication is the use of technology that allows us to communicate with others in different locations without the use of any physical connection (wires or cables). A mobile phone (also called a mobile cellular network, cell phone, or handphone) is an example of mobile communication (wireless communication).
3. Which of the following is not a service offered by SS7?
Alternate billing services
Touchstar
400 services
800 services
Answer.3. 300 Hz
Explanation
Signaling System 7 (SS7) is a set of protocols allowing phone networks to exchange the information needed for passing calls and text messages between each other and to ensure correct billing. It also allows users on one network to roam on another, such as when traveling in a foreign country.
There are three main types of services offered by the SS7 network. They are the Touchstar, 800 services, and alternate billing services.
4. On which of the following frequencies does a Wi-Fi network work?
2.4 MHz
5 MHz
10 GHz
5 GHz
Answer.4. 5 GHz
Explanation
Wi-Fi is the wireless network system most commonly used in homes to connect multiple electronic devices through the internet. An instrument called a router is needed to connect several instruments through the internet.
WiFi uses radio frequencies to send signals between devices. WiFi works at a frequency of 2.4 GHz and 5 GHz.
5. If the voice activity interference reduction factor is 2.5, antenna sectorization gain factor is 2.5, and interference increase factor is 1.6, then the performance improvement factor in CDMA digital cellular system is
1.2
2.5
3.1
3.9
Answer.4. 3.9
Explanation
Given voice interference reduction factor and antenna resize factor is 2.5 and 2.5 respectively.
The interference factor is 1.6
Performance Improvement Factor = GV.GA/P
Where
GV: Voice interference reduction factor
GA: Antenna sectoring factor
P: Interference increase factor
= 2.5 × 2.5/1.6 = 3.9625
Performance improvement factor = 3.9
6. Global positioning system (GPS) uses:
CDMA
SDMA
TDMA
FDMA
Answer.1. CDMA
Explanation
The global positioning system (GPS) is a network of satellites and receiving devices used to determine the location of something on Earth. Some GPS receivers are so accurate they can establish their location within 1 centimeter (0.4 inches). GPS receivers provide location in latitude, longitude, and altitude.
Global positioning system (GPS) uses CDMA.
CDMA (Code Division Multiple Access) uses a digital modulation technique called Direct Sequence spread spectrum which spreads voice data over a very wide spectrum using user or cell-specific pseudo-random codes.
7. What is wireless communication?
Sending data from one location to with the use of a physical medium
Sending data from one location to another without the use of a physical medium
Sending data from one location to another without the use of virtual medium
None of the mentioned
Answer.2. Sending data from one location to another without the use of the physical medium
Explanation
Wireless Communication is a method of transmitting information from one point to other, without using any connection like wires, cables, or any physical medium. Generally, in a communication system, information is transmitted from transmitter to receiver that is placed over a limited distance.
8. Which of the following is true for first-generation wireless systems?
Low rate
Efficient
High data rate
Digital technology
Answer.1. Low rate
Explanation
1G or (1-G) refers to the first generation of wireless telephone technology (mobile telecommunications). These are the analog telecommunication standards that were introduced in 1979 and the early to mid-1980s and continued until being replaced by 2G digital telecommunications.
First-generation wireless systems provide analog speech and inefficient, low rate, data transmission between the base station and mobile user.
First-time calling was introduced in mobile systems.
It used analog signals.
It used an FDD scheme and typically allocated bandwidth of 25 Mhz.
The coverage area was small.
No roaming support between various operators.
Low sound quality.
Speed :- 24 kbps.
9. If a total of 33 MHz of bandwidth is allocated to a particular FDD cellular telephone system that uses two 25 kHz simplex channels to provide full-duplex voice and control channels, compute the number of channels available per cell if a system uses 4-cell reuse
55
660
95
165
Answer.4. 165
Explanation
Given,
Cluster size (N) = 4
Total bandwidth = 33 MHz
Channel bandwidth = 25 kHz × 2 simplex channel
Channel bandwidth = 50 kHz/duplex channel
Total available channels = (33,000 × 103)/(50 × 103)
Total available channels = 660 channels
Total number of available channels per cell = (Total available channels)/N
Total number of available channels per cell = 660/4
Total number of available channels per cell = 165
10. If a cellular system has p number of co-channel interfering cells, S is the desired signal power from the serving base station and IP is interference power from pth interfering co-channel cell base station, then what is the signal to interference ratio for a mobile receiver in the functioning cell?
$\dfrac{S}{\sum_{i = 1}^P I_P}$
$\dfrac{2\times S}{\sum_{i = 1}^P I_P}$
$\dfrac{\sum_{i = 1}^P I_P}{S}$
$\dfrac{S}{I_P}$
Answer.1. $\dfrac{S}{\sum_{i = 1}^P I_P}$
Explanation
The signal to interference ratio for a mobile receiver in the functioning cell is given by:
$\dfrac{S}{\sum_{i = 1}^P I_P}$
S = Desired signal power from the desired base station
Ii = Interference power caused by the ith interfering co-channel cell base station
i0 = Number of co-channel interfering cells
The average received signal strength at any point decays as a power law of the distance of separation between a transmitter and receiver (Propagation measurements).
The average received power (Pr) at a distance ( => R from the transmitting antenna is approximated by: