## 3 Survey Results
### Networking Stack
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Nr** & **Codename** & **Custom MAC** & **Channel access** & **Routing used** & **Custom routing** & **Reactive routing** & **or** & **IPv6** & **Safe delivery** & **Data priority-** \\ \hline
19 & Biomotion & y & Time & n & - & - & n & n & n \\  & & & Division & & & & & & \\  & & & Multiple & & & & & & \\  & & & Access & & & & & & \\  & & & (TDMA) & & & & & & \\
20 & AID-N &? &? & y & n & proactive & n & y & n \\
21 & Firefighting & n & CSMA & y, static & n & proactive & n & n & n \\
22 & Rehabil & n & CSMA & n & - & - & n & n & n \\
23 & CargoNet & y & CSMA & n & - & - & n & n \\
24 & Fence monitor & n & CSMA? & y & y & proactive? & n & n & n \\
25 & BikeNet & y & CSMA & y & y & reactive & n & y & n \\
26 & BriMon & y & TDMA & y & y & proactive & n & y & n \\
27 & IP net & n & CSMA & y & y & proactive &? &? &? \\
28 & Smart home &? &? & y &? &? & n &? &? \\
29 & SVATS & n & CSMA & y & n &? & n & n & n \\
30 & Hitchinker & y & TDMA & y & y & reactive & n & y & n \\
31 & Daily morning & n & CSMA & n & - & - & n & n & n \\
32 & Heritage & y & TDMA & y & y & proactive & n & y & y \\
33 & AC meter & n &? & y & n & proactive & y & y & n \\
34 & Coal mine & n & CSMA & y & y & proactive & n & y & n \\
35 & ITS & y? & CSMA? & y & y & reactive & n & y & n \\
36 & Underwater & y & TDMA & n & - & - & n & n & n \\
37 & Pipe-Probe & n &? & n & - & - & n & n & n \\
38 & Badgers & n & CSMA & y & y & proactive & y & n & y \\
39 & Helens volcano & y & TDMA & y &? &? & n & y & y \\
40 & Tunnels & n & CSMA & y & y & proactive & n & n & n \\ \hline \hline \end{tabular}
\end{table} 
Table 12: _Cont._Routing can be proactive: routing tables are prepared and maintained beforehand; or it can be reactive: the routing table is constructed only upon need. The proactive approach is used in 85% of the cases; the remaining 15% use reactive route discovery. As already mentioned above, the operating system must provide a simple, yet efficient, routing protocol, which performs fair enough for most of the cases. A proactive protocol is preferred. _Design rule 20_: The interface for custom MAC and routing protocol substitution must be provided. Although Internet Protocol version 6 (IPv6) is a widely discussed protocol for the Internet of Things and modifications (such as 6 lowpan [73]) for resource-constrained devices have been developed, the protocol is very novel and not widely used yet: only 5% of surveyed deployments use it. However, it can be expected that this number will increase in the coming years. TinyOS [4] and Contiki OS [5] have already included 6 lowpan as one of the main networking alternatives. _Design rule 21_: It is wise to include a IPv6 (6 lowpan) networking stack in the operating system to increase interoperability. Reliable data delivery is used by 43% of deployments, showing that reliable communication in the transport layer is a significant requirement for some application classes. Another quality-of-service option, data stream prioritizing, is rarely used, though (only 10% of cases). _Design rule 22_: Simple transport layer delivery acknowledgment mechanisms should be provided by the operating system.