## 2 Background  
### Missions and Requirements  
A major motivating example of the need for MAV networks is shown in Figure 1. In this example, a MAV has dropped a number of nodes in an unknown environment, and is wirelessly communicating with a base station over the resulting stationary infrastructure. A star topology on the underlying network would limit communication to only those nodes a single hop from the base station, while a multihop tree topology would be susceptible to loss of connectivity from the failure of a single node. As such, the network must form a multihop mesh topology, where nodes can have multiple neighbors, and data can pass through several nodes on their way to and from the base station. These stationary network nodes serve the purpose of relaying information between the MAV agent and the base station, while also acting as a long-term persistent sensing platform, which can be left in place indefinitely to collect information about its environment. The challenge of designing such a system thus lies in adapting the wireless network to both long-term, low data rate reliable sensing missions, while accommodating the burst of short-term, high data rate transmissions of MAV agents. The specific MAV mission will define the tradeoffs necessary to design its underlying network. However, many of those design decisions can be accomplished by tuning various parameters in a general framework. At its most general, a MAV mission has the following components:  
* Navigate through the environment
* Deploy sensors and repeater nodes
* Relay data back from MAV and deployed sensors  
The arbitrary topology of an unknown environment means that line-of-sight communication from the MAV to the outside world is often impossible. Thus, the MAV must carry along and deploy a payload of repeater nodes along its flight path. These drop-off nodes must establish a wireless network over which the MAV can communicate to an external base station. The objective of the general MAV mission is to relay data from inside the unknown environment to the outside world. This data can come from the sensors on the MAV, using the deployed network nodes merely as a communications infrastructure, or it can also be generated by sensors on the deployed nodes themselves. In the case of reconnaissance-type missions, data from MAV sensors will be composed of short, high volume bursts (camera feeds, microphones, _etc._). The stationary network nodes will generate low rate data over the long-term for purposes of anomaly detection or the monitoring of slowly-changing environmental phenomena (footstep detection, smoke detection, _etc._). Figure 1: This schematic shows a deployed wireless sensor network infrastructure for a MAV mission. The laptop represents a base station and acts as a network manager, coordinating communications while serving as a sink for data generated by the MAV and sensor mesh. Data generated by the MAV is sent through the multihop mesh. The most significant design constraints in such missions are weight and power consumption; the two go hand-in-hand. The lower the mass of the MAV with its payload, the less power is needed to fly, thus permitting longer missions. Similarly, the lower the power consumption, the smaller and lighter the battery needed for a given mission. Since the deployed network is initially dead payload weight on the MAV, minimizing overall network power consumption minimizes the battery requirements on the dropped-off nodes (or eliminates in entirely in favor of energy scavenging sources), thus lightening the load and increasing the scope of possible missions. Guidance of the MAV can either be handled remotely, via a central base station, or autonomously through on-board processing. Remote control simplifies flight processing by offloading guidance and navigation decisions to a central operator. However, it imposes high throughput and low latency requirements on the network. On-board data must be passed rapidly to the operator to facilitate real-time control of the MAV.