ubiquiti antenna network - Uvic-Robotics-Club/uvic-rover-2027 GitHub Wiki

What is a Base Station?

Represents an access point for a wireless device to communicate within its coverage area. It acts as a radio that connects end devices (rovers) to the network backbone (our control computer). This Base Station is responsible for managing network connections, sending commands to the Rover and receiving telemetry and video feeds.

In our setup, the Rocket M2 Ubiquiti serves as a base station where it handles wireless protocol, encryption, and device management.
The omnidirectional antenna determines how far and in which pattern (directional coverage) the signal travels – in this case, a full 360 degrees.
- Slight issues, an omni-directional antenna typically has a shorter range in any single direction compared to a directional antenna.

What is a Dual Polarity Antenna?

A MIMO (Multiple Input Multiple Output) increases network bandwidth by utilizing multiple planes (2 in a dual polarization setup) for sending and receiving data. For dual polarization, this typically means the horizontal and vertical plane which allows two widely different signals to be sent and received simultaneously on the same frequency range.

A 2x2 MIMO typically means cross polarization, where two antennas will be positioned on top of one another in an “x” or “+” form. Allows for two different data streams to be sent and received simultaneously.
Why this matters? Since the rover and base station might tilt or change orientation (rover moves over uneven terrain or rotates), using dual-polarized antennas ensures that at least one polarization maintains a strong link which minimizes data loss.

What does our Communication System look like?

We are using the Rocket M2 Ubiquiti base station. This is a radio unit transceiver (2.4Ghz) that is designed for Point-to-Point wireless links. Key Specs to know:

Frequency: ~2.4GHz
Throughput: ~150 Mbps TCP/IP
Range: Claims +50 km under ideal conditions.
Services: Web Server, SNMP, SSH Server, Telnet, Ping Watchdog, DHCP, NAT, Bridging, Routing
Software: Ubiquiti’s airOS (and airMAX) features allowing TDMA scheduling, QoS, scalable client support, etc.
What is TDMA Scheduling? This is Time Division Multiple Access which allocates dedicated time slots for each client. This prevents packet collisions and reduces latency.

This will be paired with the airMAX Omni Antenna (AMO 2G10 or AMO 2G13), a 2x2 dual-polarity MIMO Omnidirectional antenna. Key Specs to know:

Coverage: 360 degrees
Frequency: 2.4 GHz
Performance: LoS (Line of Sight) or NLoS (Non-Line of Sight)
Gain: 10dbi or 13dbi (model-dependent)
Polarization: Dual Linear
Cross-Polarization Isolation: ≥25 dB

Communication Setup

For our setup, we use two Rocket M2 Tranceivers: one for the base station and one for the Rover. At the Network Layer, the Base Station Transceiver acts as the Central Communication Hub (master) that distributes commands to the Rover, while the Rover Transceiver acts as a client connecting to the base station network.

However at the Application Layer (ROS Software), the laptop is the client, sending control commands, while the Rover is the server, executing those commands and returning telemetry.

Rover Communication Setup

The Rover’s Transceiver connects to the main microcontroller (Jetson, Raspberry Pi, or Arduino) which coordinates communication with other microcontrollers.

This ensures all subsystems (motors, cameras, sensors) communicate through a single hub before reaching the network link.

What is Serialization?

This is the process of converting structured data (like speed, sensor readings, or control commands) into a sequence of bytes that can be transmitted across a communication channel.

It occurs at multiple levels – the microcontroller interfaces (UART, SPI), the network layer (TCP/UDP packets), and the application layer (ROS messages).
Serialization ensures data integrity, compatibility between systems using different architecture, and efficient communication through compact binary or structured packet formats.