# Full-Duplex MAC Protocol for CSMA/CA-Based Single-Hop Wireless Networks
## 4 Numerical Simulation and Analysis
The values of the parameters used in the simulation are shown in Table 1, which are consistent with those used in [2]. \(L_{RTS}\), \(L_{CTS}\), and \(L_{Ack}\) denote the size of the RTS, CTS, and Ack frames, respectively. The first two are used in the traditional CSMA/CA protocol. Subsequently, in Figure 9, we provided the numerical simulations for the performance of our proposed FD MAC protocol and compared it with that of the CSMA/CA protocol traditionally applied to the HD networks. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Frame payload & 8184 bits \\ Frame header & 272 bits \\ Channel rate & 1 Mbps \\ ACK frame & 112 bits \\ Slot time & 50 us \\ RTS frame & 160 bits \\ CTS frame & 112 bits \\ SIFS & 28 us \\ DIFS & 128 us \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Value of each simulation parameter. In general, regardless of the values of \(n\) and \(W\), compared with the traditional CSMA/CA protocol, our protocol can significantly (at least twice) increase the system throughput. Basically, at a time slot, the \"active\" transmission probabilities of the nodes for the two protocols are similar. When only one node \"actively\" sends the frame, the latter produces twice as much throughput as the former. Furthermore, when two nodes \"actively\" send the frames, according to the traditional CSMA/CA protocol, a collision will occur. However, our protocol can coordinate the FD communication. For the proposed FD MAC protocol, we further discuss two details. First, as shown by the \(Th_{FD}\) curve in Figure 9, when \(n=5\) and \(W>40\), the value of \(Th_{FD}\) will decrease as \(W\) increases because when the size of \(W\) is large, the probability that each node is in the \(T_{1}\) state is low. If we have only a small value of \(n\), then the network is more likely in the idle state. For example, when \(n=5\) and \(W=64\), the sum of \(P_{sgl}\) and \(P_{dbl}\) is only 0.1156, while \(P_{idle}=0.8843\). Although the value of \(T_{idle}\) is much smaller than the transmission time of the frames, according to Equation (26), the larger \(P_{idle}\) and smaller \(P_{sgl}\) and \(P_{dbl}\) will also reduce the system throughput. Second, when the value of \(n\) is large and the size of \(W\) is small, the value of \(Th_{FD}\) is low. This is because in these cases, contrary to the above, the network is more likely to be in the collision state. For example, when \(n=30\) and \(W=8\), we have \(P_{col(FD)}=0.9759\), and the transmission collisions in the network waste considerable channel access time. Given that \(P_{col(FD)}<P_{col(HD)}\), this problem is more prominent in the traditional CSMA/CA protocol. In this case, the value of \(Th_{HD(basic)}\) is close to 0. Note that when the protocol uses the RTS/CTS mechanism, the system throughput will be significantly increased because although this mechanism cannot change the value of \(P_{col(HD)}\), it can reduce the channel access time wasted by the collisions from \(T_{Hdr}+T_{Pyl}\) to \(T_{RTS}\). Furthermore, in Figure 10, we kept the contention window of the nodes unchanged and compared the throughput produced through our protocol and that in [5] (denoted by \(Th_{FD(basic)}\)) versus the different value of \(n\). Here we assumed that \(W=32\). When \(W\) takes on other values, we have similar conclusions. Figure 9: System throughputs for the proposed FD MAC protocol and the traditional CSMA/CA protocol versus the different values of \(n\) and \(W\). In [5], the contention mechanism of the nodes is \(p\)-persistent CSMA, where \(p\) is considered to be the \"active\" transmission probability at each time slot. Briefly speaking, when a node senses that the channel is idle, at the first time slot, it sends the frame with probability \(p\). Even if it does not send the frame at this slot (with probability 1-\(p\)), the probability that it sends at the second time slot is still \(p\), and so on. The nodes have no contention windows.