e-Parking Meter Management System

 

 

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Hardware:

 

The efficient parking meter consists of three modules: a sensor, a control unit and a transmitter.  Figure 1 shows a block diagram for a parking meter illustrating the three components.

 

Figure 1: A smart parking meter

 

Sensor:  Each parking meter will have a sensor that is able to detect the presence or absence of a car in its spot.  There are a variety of technologies that could be employed for that purpose, ranging from infrared detectors to rudimentary “radar-like” systems that could be combined with the communication sub-system.  In a real system, the choice of a particular technology is likely to be mostly driven by cost considerations.  However, our project is not concerned with the sensor; we will simply assume that a meter is able to detect the presence of a car and pass that information on to the control unit.

 

Control Unit:  The control unit takes input from the sensor and the coin-collecting mechanism (neither of which we will be implementing) and is responsible for implementing the protocol that relays all that information from each parking meter to the central station.  The control unit for our parking meter is a StarEast board.  The baseboard for this platform is based on an Intel® IXP425 network processor and includes 256 MB of on-board SDRAM, and 16 MB of on-board Intel StrataFlash® memory.  The board can support up to two miniPCI cards, one of which will be used for an 802.11b wireless card, and a USB 1.1 port.  The operating system is Linux.  The board controls the wireless card in an efficient manner.  Meter status is determined by the presence or absence of a car and amount of money in the meter.  A packet is formed and made available for transmission.  The parking meter is also able to get the status of nearby meters.  In an effort to combine packets and save energy, the control unit can combine the information from many meters without omissions or duplications.  The responsibility of routing the packets also falls on the control unit.

 

Transmitter:  The transmitter is used for communicating with other parking meters and access points and is responsible for the actual transmission of packets.  A miniPCI wireless card is being used for this.  The wireless protocol used for transmission is IEEE802.11b.  The transmitter has to switch between ad-hoc mode and infrastructure mode.  Ad-hoc mode is used for parking meters to communicate among themselves while infrastructure mode is used for communications between parking meters and wireless access points.

 

Figure 2: One of our parking meters

 

Overall System:  Each parking meter is only a small unit in the overall system.  The entire system is composed of parking meters, access points and the central office.  Parking meters are pre-configured into Groups based on their geographical location.  All parking meters in a Group communicate with each other, either directly or in a multi-hop fashion by acting as relays for other parking meters, and work together to collect and combine information before sending it to the central station for processing.  Each Group has a head meter that collects information from all parking meters in its Group and sends it to the central station through the access point.  In order to distribute power use evenly and that way extend the life of the system as a whole, the head meter position is rotated among all parking meters in the Group.  Therefore, each individual parking meter at one point or another adopts three roles: sender of information to another parking meter, recipient of information from other parking meters, and sender of information to an access point.  The access points then relay the information all the way to the central office where it is examined through a user interface and violations can be identified.  Figure 2 shows a diagram of a Group.  Figure 3 shows a diagram of a city-wide network.

 

Figure 3: A city-wide network