Bus Lot Wireless Network Installation Guidelines

Bus Lot Wireless Network Installation Guidelines

The Transportant system requires a wireless network in the bus parking lot. This guide collects Transportant's experience assisting customers with building and troubleshooting those networks.

Environmental Concerns

In rare cases, other activity in the surrounding area can interfere with wireless networks use of the unregulated 2.4 GHz and 5 GHhz spectrum. Examples are the use of radar (e.g. near military bases) or other facilities that manufacture or use large amounts of same-spectrum wireless gear, such as a baby monitor factory.

Upstream Networking Requirements

Upload Bandwidth

Site bandwidth requirements for video upload based on typical use patterns are 60-120 megabits per second, per 100 school buses. For example, a 200 bus school lot might need as much as 240 megabits of upstream bandwidth. These estimates are on the common average of 1 hour of offload video per 10 buses, and a 6 camera bus system.

Network Segmentation

For security reasons, we recommend that the bus network be isolated from the rest of the network. Devices on the bus network should be able to make connections out to the Internet, but not to other parts of the organization's network.

IP Address Ranges

Please avoid using the address range 172.16.0.0/12 for the bus parking lot network segment. Using that address will complicate routing, as this is the network range the buses use for serving student Wi-Fi clients.
Please note that "172.16.0.0/12" includes addresses from 172.16.0.0 through 172.31.255.254 because of the /12 netmask.
Not everything in the district needs to be modified to not use 172.16.0.0/12, just the specific subset the buses connect to. It is fine if other adjacent or upstream subnets use those ranges.

Firewall Allow Lists

In most cases, no changes will be necessary. Buses will make VPN connections to Transportant's upstream cloud services. In some cases, it may be appropriate to allow-list these addresses to prevent firewalls from identifying the reply traffic as a denial of service attack. The buses make UDP connections to the following IP addresses on ports 8172-9173:
  1. 159.89.253.199
  2. 138.68.248.111

Allow Unattended Access Without User Interaction

The wireless network must allow for devices to connect and reach the Internet automatically, without prompting a user for agreement to terms of service or subsequent browser based authentication. Operations of the bus networking systems are automated, so there will be no user to consent to such agreements or perform subsequent authentication steps.
We do not recommend using a hidden SSID, but it is possible. It requires extra work to configure and makes troubleshooting more difficult as we offload video from buses. It does not improve security.

Access Point Placement Near Buses

Transportant adds external wireless antennas to the roof of most buses. In some unusual cases where roof installation is problematic, antennas may be installed on the side of a bus instead of near the roof.
Placing access points (APs) near the school buses in parking lots is the most important step.
  1. Access points should be at a minimum height of 10 feet above the roofline of a bus.
    1. Typically this means an access point mount height of 20 feet or more.
    2. Standard utility/light poles with band and screw mounting are a common choice.
  2. Every bus should be within 150 feet of an access point.
  3. Access points should be within 200 feet of each other.
  4. Every bus should have a line of sight from the front-middle of the roof to at least one access point.
  5. To avoid access point over-saturation, each access point should serve no more than 10-20 buses. Over-saturation will increase offload times, leading to buses shutting down before completing offloads and updates.
The most common problems we see in access point placement are:
  1. Access points placed at an insufficient height
  2. Access points placed too far away from buses
  3. Parking arrangements where some buses occlude others
    1. Buses are metal, so Wi-Fi signal does not pass through them reliably
    2. Signal may, however, reflect around occlusions from other surfaces to create confusing situations where things sometimes work
    3. It's important to test signal strength when most buses are present
Low access points increase data loss
Higher access points reduce data loss
Keeping all that in mind let’s take a look at a smaller lot with 32 buses:
Lot with 32 buses
And here’s a bigger lot with 180 buses:
Lot with 180 buses
The four access points in blue would be one unique network, and each other row would also be its own unique network. In some instances, the buses would have assigned parking and multiple SSIDs would be created forcing buses to connect only to assigned APs. In other instances, a single SSID may be used by all.

Access Point Network Backhaul: Wired vs Mesh

In most cases, it is not necessary to provide a wired (Ethernet) uplink connection to all access points in a parking lot. A typical network might have one or more access points that have an Ethernet connection, and these access points serve as upstream mesh connections to other access points located deeper in the parking lot. Access points should preferably be within 200 feet of an upstream access point.

Access Point Power

Most bus parking lots already have power on-site for light poles, engine heaters, battery chargers, and other accessories. Transportant also offers solar/battery power kits for access points, that in many environments can eliminate the need to supply power. We recommend unswitched or dedicated power. Please note: solar solutions require UAP-AC-M (not Pro) and shorter distances between access points.

Specific Hardware Recommendations

We use and recommend Ubiquity outdoor mesh access points priced around $200:
  1. UAP-AC-M-PRO AC Mesh Pro, 10db omni directional
  2. UAP-AC-M AC Mesh used in conjunction with UMA-D AC Mesh Dual-Band Antenna, 10db directional, for greater distance
  3. For a gateway router and Power Over Ethernet (POE) injector: Router, POE switch

Network Troubleshooting

  1. Turn on all the buses and confirm they are live on the Buses page.
  2. Look at the Wifi Report - it may be easier to copy it to an excel sheet.
    1. First sort by time. Any buses that have not connected to the Wi-Fi network in the last 10 minutes are not getting a good signal.
      1. Then sort by Wi-Fi quality. Any buses that say Not Good are not getting a good signal.
    2. Finally, sort by frequency. You want buses to see 5000 or above. Any buses around or below 2400 are not getting a good signal.
  3. Then you can reference the map of where your buses park and figure out if there are zones that need attention.

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