MGRMB

Question 3 [20 Marks] Multiple technique access techniques are used to increase the number of users to access the communications system with the shared spectrum at the same time. In Satellite communications, based on the Shannon Capacity Theorem, one approach to increase the number of simultaneous users is to improve the capacity of utilized multiple technique access technique through the power of transmitted signals. And another way is to change the bandwidth efficiency through utilized modulation scheme. Since the capacity of system is in nonlinear relation with the power of signal, and bandwidth efficiency, we have to consider different region for signal power and bandwidth efficiency to calculate the rate of capacity improvement. As a design problem, to increase the number of users by a factor of two, we consider the following cases: i) Case 1: Increasing the number of users from 2 to 4. ii) Case 2: Increasing the number of users from 8 to 16. a) For each case, calculate the required SNR for different multiple access techniques including, FDMA, TDMA, and CDMA for a given attainable modulation efficiency of 0.5. [9 Marks) b) For each case, calculate the required modulation efficiency for considered multiple access techniques for a given SNR of 30 dB. [8 Marks] c) Compare the results obtained in parts (a) and (b). [3 Marks] Question 3 [20 Marks] Multiple technique access techniques are used to increase the number of users to access the communications system with the shared spectrum at the same time. In Satellite communications, based on the Shannon Capacity Theorem, one approach to increase the number of simultaneous users is to improve the capacity of utilized multiple technique access technique through the power of transmitted signals. And another way is to change the bandwidth efficiency through utilized modulation scheme. Since the capacity of system is in nonlinear relation with the power of signal, and bandwidth efficiency, we have to consider different region for signal power and bandwidth efficiency to calculate the rate of capacity improvement. As a design problem, to increase the number of users by a factor of two, we consider the following cases: i) Case 1: Increasing the number of users from 2 to 4. ii) Case 2: Increasing the number of users from 8 to 16. a) For each case, calculate the required SNR for different multiple access techniques including, FDMA, TDMA, and CDMA for a given attainable modulation efficiency of 0.5. [9 Marks) b) For each case, calculate the required modulation efficiency for considered multiple access techniques for a given SNR of 30 dB. [8 Marks] c) Compare the results obtained in parts (a) and (b). [3 Marks]