# Cross-Layer Methods for Ad Hoc Networks--Review and Classification
## 1 Introduction
Publications [28; 38; 39; 40] focus on classifying not all cross-layer methods but cross-layer methods belonging to the same layer: cross-layer routing protocols, cross-layer transport protocols, and cross-layer applications for streaming video. [PERSON] et al. [38] consider the routing protocols for vehicular ad hoc networks. The protocols are divided into two types: with the use of composite metrics from combining the physical and channel \begin{table}
\begin{tabular}{c c c} \hline \hline
**Title** & **Year** & **Citations** \\ \hline Ref. [9]: Cross-layer design: a survey and the road ahead & 2005 & 1538 \\ Ref. [36]: Review of the cross-layer design in wireless ad hoc and sensor networks & 2010 & 8 \\ Ref. [37]: A survey of cross-layer design for VANETs & 2011 & 159 \\ Ref. [38]: Routing mechanisms and cross-layer design for vehicular ad hoc networks: a survey & 2011 & 43 \\ Ref. [39]: Survey of cross-layer proposals for video streaming over mobile ad hoc networks (MANETs) & 2012 & 28 \\ Ref. [28]: Routing in vehicular ad-hoc networks: a survey on single- and cross-layer design techniques, and perspectives & 2017 & 139 \\ Ref. [40]: A study on cross-layer [TCP] performance in wireless ad hoc network & 2018 & 12 \\ Ref. [41]: Review of cross-layer design for cognitive ad-hoc and sensor network & 2020 & 9 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Review publications on cross-layer methods in ad hoc networks. Figure 5: Cross-layer methods as the iterative optimization of multiple-layer configuration. layer metrics and joint work of the network and channel layer. [PERSON] et al. [28] deal with cross-layer routing protocols in ad hoc networks. The authors created a table with reviewed methods and what metrics and layers are used by methods. [PERSON] et al. [40] focus exclusively on the transport layer (the TCP protocol modifications) and the interaction of the transport layer with other layers to improve transport protocol performance. [PERSON] et al. [39] focus on cross-layer methods that implement video streaming applications in ad hoc networks. The authors categorized methods according to the layers used in the methods. The categorization and distribution of methods by categories are the following: 1%--all except network and transport layer, 9%--use all layers (holistic approach), 40%--all layers except application layer, 50%--application layer, network and channel layer. Every method for network control has a main goal or set of goals to achieve:  
1. **Line throughput**. Line throughput is the volume of successfully delivered data through the line per unit of time. 2. **Energy consumption**. The less the node energy spent per successful information transmission, the more battery life, and the greater the longevity of network connectivity. 3. **Line packet error rate**. Line packet error rate is inversely proportional to line throughput with regard to the line bandwidth, which is the line transmission rate. 4. **Line latency**. Line latency is the sum of multiple delays: queueing delay, propagation delay, transmission delay, etc. 5. **Route throughput**. Route throughput is the minimal throughput of lines inside the route. 6. **Route packet error rate**. Route packet error rate is the complimentary of the lines inside route probabilities of successful packet delivery multiplication. 7. **Route stability**. Route stability is how long all lines in the route remain existing and within the desired range of parameters. 8. **Route latency**. Route latency is the sum of line latencies inside the route. 9. **Interference**. Interference is the simultaneous transmission of multiple nodes when the total power of other nodes transmitted, except the sender, corrupts the received packets. Low interference is not harmful. High interference causes packet collisions. 10. **Data overhead**. The volume of service data. The more, for example, the routing protocol sends route request packets, the lower the throughput.