Question 1: Why are we not using stationary sensors only at the parking slot? Why do we need mobile sensor?

Answer: Stationary sensors are costly. From stationary sensers, we can get information only for fixed parking slot. We can get all road side parking information by using mobile sensors. Mobile sensor (ultrasonic sensor) is very cheep.

Question 2: Can we get information for multi-lane road?

Answer: Not, from this ParkNet system. Because we installed ultrasonic sensor only on one side; so, we can't get information from other side. This system was only for two-lane road side parking. If we install more sensors, we can get information from other sides. But, the cost will be increased.

Question 3: How to solve the problem with big data?

Answer:The authors didn't focus on this problem.