It Is Urgent: Due In 15 Hours — 5 Questions

It Is Urgent It Is Due In 15 Hours5 Questions1 If You Have 20 Sta

It is urgent. it is due in 1.5 hours. 5 questions: 1. If you have 20 stations all connected to the same wire and all using digital transmission. What method of sharing the media must be used? Why do you need a sharing method?

2. Wiring specifications for a protocol such as Ethernet have a maximum length for a wire between two stations. Why does there have to be a maximum length for a wire?

3. What transmission impairment(s) are improved when moving from twisted pair to coax cable?

4. What are the three types of transmission circuits? Briefly describe each.

5. List the different types of modulation and briefly describe each.

Paper For Above instruction

In modern digital communication networks, the method of sharing media among multiple stations is crucial for efficient and collision-free data transmission. When 20 stations are connected to the same physical wire and utilize digital transmission, a media access control (MAC) protocol must be employed. One common method is the Carrier Sense Multiple Access with Collision Detection (CSMA/CD), especially in Ethernet networks. CSMA/CD allows stations to listen to the medium before transmitting to avoid collisions, and in case-of collision detection, it ensures data integrity. This sharing method is necessary to prevent data collisions that occur when multiple stations transmit simultaneously, causing loss or corruption of information. Without an effective media sharing mechanism, the network might encounter frequent collisions, leading to reduced throughput and degraded performance, particularly as the number of stations increases (Tanenbaum & Wetherall, 2011).

Wiring specifications, such as maximum cable length in Ethernet standards, are critical to maintaining signal integrity and network performance. The primary reason for this max length restriction is the signal attenuation and timing constraints inherent to the physical medium. As signals travel over cables like twisted pair or coaxial, they weaken — a phenomenon known as attenuation. If the cable is too long, the signal deteriorates and becomes indistinguishable from noise, leading to increased error rates. Moreover, in protocols like Ethernet, maximum length ensures timing accuracy for collision detection — essential for the CSMA/CD mechanism to function properly. If a station cannot detect a collision due to long wiring, it might transmit simultaneously with another station, resulting in data corruption (Keshav, 1997).

Switching from twisted pair to coaxial cables substantially improves transmission in various impairments. Twisted pair cables are prone to electromagnetic interference (EMI) and crosstalk, which can distort the transmitted signal. Coaxial cables, with their solid metal shield, significantly reduce susceptibility to external EMI, providing a cleaner signal path. Consequently, moving to coaxial cables enhances the signal-to-noise ratio (SNR), reducing noise-induced errors. Furthermore, coaxial cables support higher bandwidths, allowing for faster data transmission rates. They also offer better shielding that minimizes crosstalk between signals, which is a common issue in twisted pair cables especially in high-density environments (Oppenheim & Willsky, 1996).

There are three main types of transmission circuits, each serving different communication needs: (1) Simplex circuits, (2) Half-Duplex circuits, and (3) Full-Duplex circuits. Simplex circuits allow data to travel in only one direction—like traditional radio broadcasting—meaning communication is unidirectional. Half-duplex circuits enable two-way communication, but only one station can transmit at a time; a good example is walkie-talkies, where users take turns speaking. Full-duplex circuits provide simultaneous two-way communication, allowing stations to send and receive data simultaneously, akin to telephone conversations. Each type suits different applications depending on communication latency, complexity, and bandwidth requirements (Gagliardi, 1991).

Modulation is the process of varying a carrier wave to encode information, and several types enable different communication requirements. Amplitude Modulation (AM) varies the amplitude of the carrier wave, traditionally used in radio broadcasting. Frequency Modulation (FM) varies the frequency and provides better noise immunity, common in audio transmissions. Phase Modulation (PM) varies the phase of the wave, often used in satellite and digital radio. Digital modulation schemes include Phase Shift Keying (PSK), where the phase is changed to encode digital data; Quadrature Amplitude Modulation (QAM), which combines amplitude and phase variations to increase data rates; and Frequency Shift Keying (FSK), which uses different frequencies to represent digital bits. Each modulation type is selected based on bandwidth efficiency, power constraints, and noise resilience (Proakis, 2001).

References

• Tanenbaum, A. S., & Wetherall, D. J. (2011). Computer Networks (5th ed.). Pearson.
• Keshav, S. (1997). An Engineering Approach to Computer Networking. Addison Wesley.
• Oppenheim, A. V., & Willsky, A. S. (1996). Signals and Systems. Prentice Hall.
• Gagliardi, R. M. (1996). Digital Communication. Thieme.
• Proakis, J. G. (2001). Digital Communications (4th ed.). McGraw-Hill.
• Forouzan, B. (2007). Data Communications and Networking. McGraw-Hill.
• Stallings, W. (2007). Data and Computer Communications. Pearson.
• Kurose, J. F., & Ross, K. W. (2010). Computer Networking: A Top-Down Approach. Addison Wesley.
• Rappaport, T. S. (2002). Wireless Communications: Principles and Practice. Prentice Hall.
• Haykin, S. (2001). Communication Systems. John Wiley & Sons.