## 5 Hybrid Network
### MAV Burst Mode  
When the MAV has high volumes of data to transmit, or when latency is a primary concern, sending packets through existing mesh traffic becomes insufficient. In this case, the MAV requests a network mode switch in its ADV ACK. If this is confirmed by the stationary node in the MAV slot (see Figure 5), then a dedicated multihop route will be opened up between the MAV and the base station. This route from MAV to base station is determined during standard operation of the mesh, e.g., as described in [10], and is unlikely to change over the duration of a slot-frame. Starting from the node in contact with the MAV, each node in the mesh informs its direct parent of the mode switch, and then shifts to the burst mode.  
This upstream notification can happen in two ways. The standard TSMP communication could be used, in which case the notification would reliably propagate upstream over the course of a slot-frame. Burst mode could then be executed in the following slot frame. Alternately and preferably, a separate slot following the MAV slot could be dedicated to this function, in which every node would listen for a mode-switch notification, and immediately switch to burst mode if required.  
Figure 4: If the MAV has a small amount of data to send, it can request a number of slots to communicate to its nearest neighbor in the mesh. These slots can be predetermined by the manager or stationary nodes. That data then gets routed over the mesh as would any other data generated in the mesh.  
Figure 5: In burst mode, the nodes along the direct path from the MAV to the base station remove themselves from the TSMP network and communicate in a separate high throughput, low latency mode.  
The burst mode communication happens over an independent set of channels from the main mesh. During the streaming mode slot-frame, nodes not involved in the direct path from the MAV to the base station carry on network operations as usual. Meanwhile, those nodes directly in-route between the MAV and base station establish a separate communications schedule over their channels. While burst communication schedule is similar to the standard TSMP communication, there are a number of important differences.  
Since the data is a single, unidirectional, burst mode stream over a predefined path, most of the TSMP headers can be stripped out of the packets to yield a higher data throughput. For similar reasons, the slot length can be narrowed to transmit at maximum radio output (about 5 ms per slot in an IEEE 802.15.4E setting) to facilitate higher packet density. For a standard IEEE 802.15.4E network, this can have the effect of doubling the number of available transmission slots. Link level ACKs are also eschewed in favor of higher bandwidth as this sort of data typically does not require very high reliability. This mode is shown in Figure 5.  
This burst mode subnetwork persists for one slot-frame. On the next frame, the network returns to its original state. Data still in transit along the path can either be discarded or stored for transmission over the default channels. If the MAV has additional data it needs to transmit, it can again request burst mode operations by responding to the next ADV packet it receives.