Mcc Quiz II & III

Fading of received radio signals in a mobile communication environment occurs because of multipath propagation. This phenomenon is caused by the signals taking multiple paths to reach the receiver. These paths can include reflections, diffractions, and scattering, leading to the signals arriving at different times and with varying strengths. As a result, the signals can interfere with each other, causing fading or fluctuations in the received signal strength.

In wireless LAN, there are many hidden stations, which are devices that are out of range or blocked by obstacles from detecting each other's signals. As a result, collisions can occur when two or more hidden stations transmit data simultaneously, leading to a loss of data integrity. Therefore, in this scenario, we cannot detect collisions in wireless LAN.

The basic GSM (Global System for Mobile Communications) is based on connection-oriented traffic channels. This means that a dedicated connection is established between the sender and receiver for the duration of the communication, ensuring a reliable and continuous connection. This is in contrast to connectionless communication where each packet is treated independently and may take different routes to reach the destination. Packet switching and circuit switching are alternative methods of handling communication, but in the context of the basic GSM, the emphasis is on connection-oriented communication.

Omni directional antennas are the correct answer because they radiate and receive signals equally in all directions. In the context of centre excited hexagonal cells, omni directional antennas would be suitable as they allow for a wider coverage area and can communicate with multiple base stations simultaneously. Sectored directional antennas, on the other hand, have a narrower beamwidth and are more suitable for providing coverage in specific sectors. Yagi uda antennas are also directional antennas and would not be ideal for center excited hexagonal cells as they have a more focused beam pattern.

A directional antenna is designed to focus its energy in a specific direction, rather than radiating it equally in all directions. This type of antenna is commonly used to improve signal strength and coverage in a specific area or towards a specific target. It is able to achieve higher gain and better signal quality compared to other types of antennas, making it ideal for long-distance communication or point-to-point connections.

The first statement is false because the cells or subdivisions of a geographical area can be hexagonal, but they can also be other shapes such as squares or circles. The second statement is true because a land to mobile call does originate through the telephone exchange.

The given statement mentions that the system is characterized by very small cells, especially in densely populated areas. This characteristic aligns with the 2.5G system, which was an intermediate technology between 2G and 3G. 2.5G systems were known for their improved data transfer rates and the ability to support limited internet access, making them suitable for densely populated areas. Therefore, the correct answer is 2.5G system.

The radio transmitting equipment at the cell-site operates at considerably higher RF power than do the mobile equipments. This means that the cell-site equipment has a much stronger signal compared to the mobile devices. This is necessary to ensure that the signal can reach a larger area and provide coverage to multiple mobile devices within that area. The higher power allows for better signal strength and quality, ensuring reliable communication for the mobile devices connected to the cell-site.

A basic service set is a set that can create either a stationary or mobile wireless station and can also have an optional central base station. It is the fundamental building block of a wireless network, providing connectivity for devices within a limited range. The other options, extended service set, network point set, and access point, do not encompass the full functionality of a basic service set.

An access point is a logical component within a wireless terminal that allows the terminal to connect to a distribution system (DS). It acts as a bridge between the wireless terminal and the DS, providing access to the network. The access point is responsible for transmitting and receiving data between the wireless terminal and the DS, allowing the terminal to access the resources and services available on the network.

In IEEE 802.11 WLAN standard, the physical layer specifies 2 Mbps data rate. DSSS (Direct Sequence Spread Spectrum) is a baseband modulation technique used in this standard. DQPSK (Differential Quadrature Phase Shift Keying) is a carrier modulation scheme that is commonly used with DSSS. Therefore, the correct answer is DQPSK.

A wireless terminal can only be associated with one access point at a time because it needs to establish a direct connection with the access point in order to access the network. Associating with multiple access points simultaneously would result in interference and instability in the connection. Therefore, the correct answer is that a wireless terminal can be associated with one access point only.

The air interface in a cellular system refers to the wireless communication link between the mobile subscriber (user's device) and the cell-site (base station). This interface is responsible for transmitting and receiving voice and data signals between the mobile subscriber and the network infrastructure. It allows the mobile subscriber to connect to the cellular network and access various services provided by the network operator.

In practical WLAN installation, the radio coverage area of the AP is usually larger than that of the wireless terminal in the same operating environment. This is because the AP is designed to provide coverage to multiple wireless devices within its range, whereas the wireless terminal is designed to receive signals from a single AP. Therefore, the AP needs to have a larger coverage area to ensure that all the devices within its range can connect to it and access the network.

Generally, one Tx antenna and two Rx antennas are used at each cell-site or each sector of a cell in a cellular system. This configuration allows for the transmission of signals from the cell-site to the user equipment (Tx antenna) and the reception of signals from the user equipment to the cell-site (two Rx antennas). Having two Rx antennas increases the system's capacity and improves the quality of the received signals by reducing interference and improving diversity reception.

The correct answer is "Fixed and wired". This mode is used for installing networks in wireless communication device characteristics. In this mode, the network is set up with fixed access points that are connected through wired connections. This allows for a more stable and reliable connection compared to a mobile and wireless mode, where the access points are not fixed and the connection can be more prone to disruptions.

Wireless access interface cards are installed as an add-on unit with the wireless access points. These cards enable the access points to connect to the wireless network and provide wireless connectivity to devices. They act as the interface between the access points and the network, allowing the access points to transmit and receive data wirelessly.

In the IEEE 802.11 WLAN system operating at a 2 Mbps data transmission rate, the size of a file transferred in 8 seconds is 2 MB. This can be calculated by multiplying the data transmission rate (2 Mbps) by the time taken (8 seconds) and converting the result from bits to bytes. Since 1 byte is equal to 8 bits, the file size transferred would be 2 MB.

The data transfer time for a fixed size file decreases by two times in the IEEE 802.11 WLAN system operating at 2 Mbps as compared to that of at 1 Mbps.

The correct answer is IEEE 802.11b WLAN standards. This is because IEEE 802.11b is a specific standard within the Wi-Fi technology that specifies the use of the 2.4 GHz frequency band and provides data transfer rates of up to 11 Mbps. It was one of the earlier standards introduced and is still widely used today, although it has been surpassed by newer standards such as IEEE 802.11g and IEEE 802.11n.