# Optical Wireless Fronthaul-Enhanced High-Throughput FC-AE-1553 Space Networks
## 4 Network Resource Allocation Algorithm Design for the HSN
### Periodic Traffic Allocation Scheme  
Periodic traffic \(Per\_Traffic_{j}\) is predictable traffic whose transmission size \(l_{j}\), period \(pt_{j}\), source \(s_{j}\), and destination \(d_{j}\) are determined. In space application networks, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Space Traffic Type** & **Rate** & **Time Sensitivity** & **Reliability** & **Traffic Freq.** \\ \hline Spacecraft system status & \(10^{3}\) bps & High & High & Periodic \\ Mission management & \(10^{3}\) bps & High & High & Bursty \\ Space navigation and & \(10^{3}\) bps & High & High & Periodic \\ localization & \(10^{1-2}\) bps & High & High & Periodic \\ Time & \(10^{1-2}\) bps & High & High & Periodic \\ Voice & \(10^{4-6}\) bps & High & Middle & Bursty \\ Video & \(10^{7-8}\) bps & Middle & Middle & Bursty \\ File & \(10^{4-7}\) bps & Low & Middle & Bursty \\ Astronomical observation & \(10^{8-9}\) bps & High & Low & Bursty \\ Experiment & & & & \\ Biology and & \(10^{6-8}\) bps & Low & Low & Bursty \\ biorechnology experiment & & & & \\ Material science & \(10^{3-4}\) bps & Low & Low & Bursty \\ experiment & & & & \\ Physical science & \(10^{3-6}\) bps & Low & Low & Bursty \\ experiment & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics of space traffic. the network bandwidth occupied by periodic traffic is extremely small (e.g., broadcasting time, broadcasting attitude information, etc.). \[Per\_Traffic_{j}=\left[s_{j},\ d_{j},\ p_{j},\ l_{j}\right] \tag{11}\]  
All the periods of periodic traffic can be divided by the time of the small cycle \(SP\). The larger the small cycle, the higher the network bandwidth utilization. The shorter the time of the small cycle, the more flexible the traffic allocation, and the shorter the time it takes for traffic to be transmitted. The small period can be divided by the greatest common divisor of the periods of all tasks, ensuring that periodic tasks can be arranged in an orderly and spaced manner within the periodic zone. \[\frac{GCD\{pt_{1},pt_{2},\cdots,pt_{N}\}}{SP}\ \in Z_{+}^{*} \tag{12}\]  
In space application systems, the periods of periodic traffic are usually on the order of seconds, whereas the period of the small cycle is usually on the order of microseconds. Periodic traffic is not required to be transmitted one by one and scheduled in different small cycles so that the ratio \(\eta_{i}\) is kept relatively small. If there are only a few periodic traffic  
When the minimum period of the periodic traffic is the greatest common denominator of all periodic traffic (in space information systems the periods are always integer multiples of 0.5 s), different types of periodic traffic will not occur in the same small cycle, as a type of periodic traffic will not repeat before the period limit is reached. \(n_{period}\) denotes the number of periodic traffic transmissions in one small cycle, and it increases linearly with the total number of periodic traffic, \(N\), as shown below. \[n_{period}=\left\{ \begin{array}{l}[1:0],\\ [2:0]\\...\\ [n_{pt}:0],\end{array} \right. \begin{array}{l}N\leq\frac{MIN\{pt_{1},pt_{2}, \cdots,pt_{N}\}}{SP}\\ (n_{pt}-1)\frac{MIN\{pt_{1},pt_{2},\cdots,pt_{N}\}}{SP}<N\leq 2\frac{MIN\{pt_{1}, pt_{2},\cdots,pt_{N}\}}{SP}\end{array}  \tag{14}\]  
To facilitate time-slot management, the small cycle is divided into a number of equal parts, \(\Delta\tau\), which is the minimum particle size. \(N_{s}\) indicates the number of slices in one small cycle. \[\frac{SP}{\Delta\tau}=N_{s} \tag{15}\]  
The occupation by the traffic in a small period can be represented by the time-slot array \(ST\). \(t_{l}\) denotes the index of the time slot. \[ST[t_{l}]=\left\{ \begin{array}{l}0,\;\;unoccupied\\ 1,\;\;occupied\end{array} \right. \tag{16}\]  
\(l_{j}\) indicates the factor of \(\Delta\tau\), a multiple that denotes the allocated transmission time slot for periodic traffic, \(Per\_Traffic_{j}\).