# Optical Wireless Fronthaul-Enhanced High-Throughput FC-AE-1553 Space Networks
## 4 Network Resource Allocation Algorithm Design for the HSN
### Selecting a channel  
The connection relationship between the HSN terminals, formed by fiber channels, is represented by \(G.fEdge\), whereas the connection relationship formed by wireless visible light channels is represented by \(G.lEdge\).  
\[S=Bur\_Traffic_{k}[p][q].\ s\_id \tag{26}\]  
\[D=Bur\_Traffic_{k}[p][q].\ d\_id \tag{27}\]  
The path formed by wireless Li-Fi channels has no relay, whereas the path formed by fiber channels may cross the FC-AE-1553 backbone network, which means that the traffic needs queueing on the next jump.  
Since the arrival time of packets is random, the ideal scenario is for this type of traffic to be serviced in the next cycle, whereas the worst-case scenario is when this type of traffic has just been serviced. If the relay terminal has p levels of priority traffic, the waiting time range extends from 0 to the duration of executing the entire multi-priority queue.  
\[0\leq queueing\ time\ \leq SP\times\left(\sum_{p=1}^{P_{max}}pQ_{p,max}-p\right) \tag{28}\]  
The comprehensive cost evaluation equation is  
\[score =Bur\_Traffic_{k}[p][q].eff\_bandwidth_{uf}\times G.Edge(S,D). Bandwidth\] \[-Bur\_Traffic_{k}[p][q].ave\_latency_{uf}\times G.Edge(S,D).Latency\] \[-Bur\_Traffic_{k}[p][q].packet\_loss_{uf}\times G.Edge(S,D).Loss \tag{29}\]  
Since the transmission rates of FC and Li-Fi are not equal, the same traffic is quantized in different time slots on the FC and Li-Fi timelines.  
\[Bur\_Traffic_{k}[p][q].fc\_slot=l_{fpq},\ \ l_{fpq}\in Z_{+}^{*},l_{fpq}<N_{s} \tag{30}\]  
\[Bur\_Traffic_{k}[p][q].lif\_slot=l_{lpq},\ \ l_{lpq}\in Z_{+}^{*},l_{lpq}<N_{s} \tag{31}\]  
When choosing FC-AE-1553, the remaining time slots should not be larger than the total minus the time slot of the periodic traffic.  
Figure 9: Multi-priority execution queue.  
\[l_{fpq} \leq\frac{Bur\_Traffic_{k}[p][q].buffer}{G.fEdge(Bur\_Traffic_{k}[p][q] \_s\_id,Bur\_Traffic_{k}[p][q].d\_id).eff\_bandwidth\times\Delta\tau} \tag{32}\] \[<\left(l_{fpq}+1\right)\]  
\[l_{fpq}=\left\{\begin{array}{ll}l_{fpq},&l_{fpq}<N_{\rm s}-\sum_{j=1}^{n}l_{ j}\\ N_{\rm s}-\sum_{j=1}^{n}l_{j},&\mbox{else}\end{array}\right. \tag{33}\]  
When choosing Li-Fi,  
\[l_{fpq} \leq\frac{Bur\_Traffic_{k}[p][q].buffer}{G.lEdge(Bur\_Traffic_{k}[p] [q]\_s\_id,Bur\_Traffic_{k}[p][q].d\_id).eff\_bandwidth\times\Delta\tau} \tag{34}\] \[<\left(l_{fpq}+1\right)\]  
\[l_{fpq}=\left\{\begin{array}{ll}l_{fpq},&l_{fpq}<N_{\rm s}\\ N_{\rm s},&\mbox{else}\end{array}\right. \tag{35}\]  
**Filling in the timeline**  
It is assumed that the FC time-slot occupancy is represented by the array FC_ST and the Li-Fi time-slot occupancy is represented by the array LiFi_ST.  
In a small cycle, when the multi-priority bursty traffic queue selects a traffic transmission for transmission through the FC for the first time and there is an available Li-Fi time slot, the queue needs to select another traffic transmission from the queue in an orderly manner for transmission through the Li-Fi channel.  
Similarly, when the multi-priority bursty traffic queue selects a traffic transmission for transmission through the Li-Fi channel for the first time and there is an available FC time slot, the queue needs to select another traffic transmission from the queue in an orderly manner for transmission through the FC.  
If both the Li-Fi and FC time slots have been selected for the multi-priority bursty traffic queue and there are still available Li-Fi time slots, the pending traffic can continue to be selected from the pending execution list in the multi-priority bursty traffic queue in a sequential manner until the Li-Fi time slot is fully occupied.