# A Novel Self-Forming Virtual Sub-Nets Based Cross-Layer MAC Protocol for Multihop Tactical Network
## 4 Working of Algorithm
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Application Category** & **Protocols and References** & **Comments** \\ \hline \multirow{6}{*}{A cross-layer framework for SDR based multihop tactical network} & & A TDMA-based cross-layer MAC for multihop tactical networks exploits empty slots and provides route calculation using AODV control messages, whereas our proposed VSCL-MAC eliminates the use of control packets to perform route discovery and uses the same NBR\_table. All the requests for intended transmissions are forwarded directly to the selected next-hop neighbor instead of sending the broadcast message to all neighbors. It also schedules dynamic slot allocation for collision-free simultaneous data transmission, which increases the network throughput. & \\ \hline \multirow{6}{*}{Cross-layer design for routing and route discovery in VANETs} & & The protocol is designed for vehicular networks and uses stochastic approaches for global coordination and slot allocation at MAC layer, such as ant colony and particle swarm optimizations, which take uncertain convergence time. The probability distribution can change for each iteration of the algorithm. These techniques are generally not suitable for real-time, mission-critical networks. Our proposed VSCL-MAC design enables dynamic slot allocation and frequency selection autonomously without using any global coordination among nodes of the network. It provides guaranteed communication with performance gain in throughput. & \\ \hline \multirow{6}{*}{Cluster-based routing protocols for ad hoc networks} & & The designed protocols use clustering concepts to find reliable relay nodes as cluster heads and optimal paths. constant bit rate (CCBR) uses average relative velocity to elect cluster head. The cross-layer neighbor discovery ND\_HC algorithm exchanges helps messages using hexagonal clustering and GPS over TDMA. These approaches inhibit the autonomous behavior of network and induce control overhead not only in routing but also to select cluster heads. The VSCL-MAC involves no central points and exchanges minimum control messages to enable multihop routing. & \\ \hline \multirow{6}{*}{Energy-efficient and position-aware routing mechanisms for WSNs} & & The designed protocols are suitable for event-based applications and use energy levels and hop distance for data forwarding. ERS-RIP uses routing information protocol to measure optimal paths between source and destination, whereas VSCL-MAC is fully decentralized and does not incorporate any routing protocol for route discovery, which reduces control overhead induced by routing protocols. The continuous and updated neighbor information keeps the nodes updated for multihop routes without sending any extra control messages. & \\ \hline \hline \end{tabular}
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Table 12: Qualitative comparison of VSCL-MAC protocol with other cross-layer protocols. ### Quantitative Comparison with Conventional TDMA-Based MAC Design

The quantitative comparison for control and data latency is performed between proposed VSCL-MAC and conventional TDMA design for the different number of messages \(M\). We considered multiple hops to evaluate the latency for both packet types, i.e., control and data. The proposed scheme has low latency values for every hop network compared with TDMA, as shown in Figure 22. In the proposed design, with an increase in the number of hops \(k\), the number of control frames \(L\) also increases with the count of one, e.g., \(L+1\), whereas in conventional TDMA design, \(L\) is large, as each transmission consumes an individual slot for every transmission. The increase in latency lowers the maximum throughput for the channel and makes it intelligible that the network performance lessens with an increase in the number of nodes.