Wireless Communication - Study Mode

[#71] Which one of the following 2G standard is used in Japan?
Correct Answer

(C) PDC

Explanation

Solution: First, let's define 2G (Second Generation) wireless technology. 2G refers to the second generation of cellular network technology. It's a significant improvement over its predecessor (1G), offering improved digital voice quality, increased capacity, and data transmission capabilities, though at a relatively lower speed compared to later generations (3G, 4G, 5G). Now, let's examine the options: Option A: IS-136 - This is a TDMA (Time Division Multiple Access) based 2G standard, primarily used in North America. Option B: GSM (Global System for Mobile Communications) - This is a widely adopted 2G standard, used globally, but not originally in Japan. Option C: PDC (Personal Digital Cellular) - This is the correct answer. PDC is a TDMA-based 2G standard that was specifically developed and deployed in Japan. Option D: AMPS (Advanced Mobile Phone Service) - This is an older 1G analog cellular technology, not a 2G standard. Therefore, the correct answer is Option C: PDC because it was the dominant 2G cellular standard used in Japan before the widespread adoption of 3G and beyond. While GSM is a global standard, PDC held its own in the Japanese market for a considerable period.

[#72] W-CDMA works in FDD mode only.
Correct Answer

(B) False

Explanation

Solution: W-CDMA (Wideband Code Division Multiple Access) is a 3G mobile communication technology that utilizes code division multiple access (CDMA) to allow multiple users to share a single frequency band. FDD (Frequency Division Duplex) is a duplexing method where the uplink (from mobile device to base station) and downlink (from base station to mobile device) transmissions occur on separate frequency bands. The statement "W-CDMA works in FDD mode only" is False . While W-CDMA is predominantly used in FDD mode, it is also capable of operating in TDD (Time Division Duplex) mode. In TDD, the uplink and downlink transmissions use the same frequency band but are separated in time. Therefore, the statement is incorrect because W-CDMA's functionality extends beyond FDD to include TDD operation. The flexibility to operate in both modes makes it adaptable to different network deployments and frequency allocation scenarios.

[#73] Which of the following 3G standard is used in Japan?
Correct Answer

(C) UMTS

Explanation

Solution: 3G Standard: 3G (Third Generation) refers to the third generation of mobile telecommunications technology, offering higher speeds for data transmission and more efficient wireless communication compared to its predecessors. Option A: Cdma2000 Cdma2000 is a 3G mobile telecommunications standard based on code-division multiple access (CDMA). It is widely used in North America and some parts of Asia, including South Korea. However, it is not the primary 3G standard used in Japan. Option B: TD-SCDMA TD-SCDMA (Time Division Synchronous Code Division Multiple Access) is a 3G standard primarily used in China. It is a homegrown Chinese technology and not the standard used in Japan. Option C: UMTS UMTS (Universal Mobile Telecommunications System) is a 3G standard used in Europe and other parts of the world. It uses WCDMA (Wideband CDMA) as its air interface technology. Although it is a common 3G standard, it is not the standard used in Japan. Option D: UTRA UTRA (UMTS Terrestrial Radio Access) is the radio access technology used in UMTS. It is not a standalone 3G standard but part of the UMTS framework. Since UMTS is not the primary standard in Japan, UTRA is also not the answer. Correct Answer: Option A: Cdma2000 Japan predominantly uses Cdma2000 for its 3G services. The country's major telecom operators, such as KDDI, have adopted this standard for efficient mobile communication.

[#74] Which of the following is specified by a specific number of bit errors occurring in a given transmission?
Correct Answer

(C) Bit error rate

Explanation

Solution: Bit Error Rate (BER) is defined as the ratio of the number of bits received in error to the total number of bits transmitted during a specific period. The question asks which option is specified by a specific number of bit errors in a given transmission. The correct answer is Option C: Bit Error Rate . BER directly relates the number of bit errors to the total number of transmitted bits. A higher BER indicates a worse communication channel quality, with more errors occurring during transmission. Let's look at why the other options are incorrect: Option A: Equally likely event refers to a situation where each possible outcome of an event has the same probability of occurrence. This is a probabilistic concept and doesn't directly define a specific number of bit errors. Option B: Exhaustive events describes a set of events where at least one of the events *must* occur. This is also a general probabilistic concept, not directly tied to a count of bit errors. Option D: Outage event refers to a situation where the signal quality falls below a predetermined threshold, rendering the communication link unusable. While an outage event often *results* from a high bit error rate, it's not directly defined by a *specific* number of bit errors. An outage is triggered when the BER exceeds a certain level, but it doesn't describe a specific number of bit errors itself.

[#75] W-CDMA requires a complete change of RF equipment at each base station.
Correct Answer

(A) True

Explanation

Solution: W-CDMA (Wideband Code Division Multiple Access): W-CDMA is a 3G mobile communication technology that uses code division multiple access for transmitting data. It provides higher data rates and supports better voice and data communication compared to earlier technologies. W-CDMA is a part of the UMTS standard, which is used in many countries worldwide. W-CDMA requires upgrades to existing base station equipment rather than a complete change, making "False" the correct answer.