# A Novel Self-Forming Virtual Sub-Nets Based Cross-Layer MAC Protocol for Multihop Tactical Network
## 4 Working of Algorithm
In the case of data latency, TDMA uses more control frame cycles and takes a relatively great amount of time to start data transmission, as shown in Figure 23. This transpires because each SDR will have to wait for its data slots for its next data transmission, whereas in VSCL-MAC, the simultaneous data transmission in the same time slot makes the latency lower, and dynamic allocation of slots increases \(TH_{network}\) due to sub-nets formation. Figure 23: Data latency comparison between proposed design and conventional TDMA. Figure 22: Control latency comparison between proposed design and conventional TDMA. ## 8 Observations and VSCL-MAC Design Constraints

Several important observations were made over an analysis of performance measures. 1. The protocol is valid for both single and multihop communications. Moreover, each radio can be engaged in only one call at a time. 2. Increase in \(R_{t}\) and combined REQ/REQ_ACK packets significantly reduces call setup time. An increase in \(S_{d}\) has a significant impact on \(TH_{network}\). 3. Latency increases if different relay nodes are selected for control transmissions and protocol starts functioning as conventional TDMA. 4. The control packet size increments with the expansion in \(N\) and subsequently impacts call setup delay. The proposed design can deal with conventional MAC issues, i.e., transmission on different frequency sub-bands mitigates collisions and interference among radios. It does not involve retransmissions as radios transmit control messages in their slot, whereas virtual confinement of SDRs avoids collisions in data messages. The distant radios may go for retransmissions that deal with the respective TCP and ARQ mechanism provided by the network layer protocol. The VSCL-MAC protocol favors concurrent transmissions over multiple channels without disturbing each other's transmissions. It gives numerous advantages with less control signaling and can schedule bidirectional correspondence among peer nodes. Utilizing the method, a network can uphold diverse transmission strategies, i.e., broadcast and multicast, by just referring to sub-nets address. ## 9 Conclusions

In accordance with the multihop tactical communication, we proposed a novel self-forming virtual sub-nets based MAC-centric cross-layer design. Given the impact of network connectivity in MANETs, it is a difficult and essential task to manage time-sensitive communication with the dynamic behavior of the network. Therefore, we presented a distributed intelligent design that allows parallelization of computation and leads to a significant reduction in routing overhead. The proposed VSCL-MAC provides an efficient neighbor discovery process (embedded in control frames) that keeps the nodes updated about their neighbors. The design does not employ any route discovery mechanism and purges system-wide broadcast, reducing call setup time. The idea of virtual sub-nets formation enables simultaneous collision-free multihop data transmission. The self-forming and self-operating capabilities make the design stand out in terms of network throughput and lower the data latency up-to 76.98% compared to conventional TDMA. Furthermore, the qualitative comparison of the proposed design with other state-of-the-art cross-layer designs proves its validity for tactical applications. Conceptualization, S.A.K. and R.R. ; methodology, R.R. and S.A.K. ; software, R.R. and M.U.F. ; validation, R.R., S.A.K., and M.U.F. ; formal analysis, R.R. ; investigation, R.R. ; resources, F.H. ; writing--original draft preparation, R.R. ; writing--review and editing, R.R., M.U.F., and F.H. ; visualization, R.R. ; supervision, S.A.K. and R.R. All authors have read and agreed to the published version of the manuscript. This research received no external funding. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** All the data supporting the results is provided in the article.