ELEC5511 Optical Communication Systems - Assignment 3: Optical Communication System Design
ELEC5511 Optical Communication Systems
Assignment 3: Optical Communication System Design
This problem is concerned with the design of an optical communication system to meet specified system requirements for a terrestrial link.
The required specifications of the communication system are:
You are asked to select the specification for the transmitter, optical fibre, and receiver, and to determine the number of repeaters that will be required.
Assume that the wavelength of transmission is 1.55 µm
The following components are available to implement the design:
Assume that the noise bandwidth of the receiver Δ f = B/2, and that the front end preamplifier has noise current of 𝜎𝜎2 𝑡𝑡ℎ=1.7×10−16 𝐴𝐴2
i. Initially assume that a receiver sensitivity of 1500 photons/bit can be achieved.
For the fibre assume:
Hence determine the maximum length between repeaters arising from the loss limit.
ii. Calculate the dispersion limit and the corresponding maximum length of fibre.
iii. Hence specify the limiting factor that determines the maximum distance between repeaters, and specify the repeater length.
iv. Find the BER requirement for each repeater section.
v. Find the sensitivity of the PIN receiver. Does it meet the system requirements? If not, suggest how the subsystem components may be modified to meet the transmission specifications.
vi. Consider the case if an APD photodiode is used in the optical receiver. Find the optimum APD gain. Determine the sensitivity of the APD receiver. Does it meet the system requirements?
vii. Discuss how the systems performance requirements specified can be met in your design, and give a summary of the operating characteristics of your proposed system.
Constants: h = 6.626 x 10-34 Js, q = 1.6 x 10-19 C, c = 3 x 108 ms-1
Hand in: 31 /5/2023 by 23:59 online on Canvas.
