Part A: In your point of view, what are the main challenges and considerations of an outdoor link design for radio systems? [2 Marks] Part B: Virtual Private Networks are great way to establish a secure network. Explain what is a VPN and what are two different types of VPN implementations? [3 Marks] Part C: Referring the figure below. At 30km what is path-loss value in free space and Urban area at 1500MHz frequency? Mention one reason why path loss in urban area is greater than free space? [3 Marks] Path Loss Lpu (dB) Path Loss Lf (dB) 100 110 120 130 180 170 160 150 140 130 120 110 100 Path Loss in Urban Area in Large City 0 10 20 30 Distance d (km) Path Loss in Free-space 0 5 10 15 20 25 301 Distance d (km) fc-200MHz fc-400MHz fc=800MHz fc=1000MHz fc1500MHz f150MHZ c-150MHz -fc-200MH2 fc=400MH2 fc-800MHz -1000MH2 - 1500MH2