# Interference Aware Resource Control for 6G-Enabled Expanded IoT Networks
## 3 Interference-Aware Scheduling of APs and Nodes
### Proposed Algorithm
The pilot \(t^{\prime}\) at which the interference metric is maximum for a given node-AP link is assigned to node \(i\) for\(i\in N_{k}\)do for\(t\)=1:\(\tau_{p}\)do \(t^{\prime}=argmax\{\tau\in 1,2\ldots\tau_{p}\}I_{i,l,\tau}\) \(t_{i}\gets t^{\prime}\) return\(\rho_{kl}\) and \(t_{i}\)=0
```  
**Algorithm 1**Interference-aware scheduling algorithm  
``` Input : \(L\), \(\tau_{p}\), \(K\), \(\xi_{kl}\) Output : \(\rho_{kl}\) and \(t_{k},\forall k\in\{1,2\ldots K\},l\in\{1,2\ldots L\}\)  1. Initialize \(\rho_{kl}=0\) and \(\mu_{kl}=0\). 2. Each user node finds an AP with the strongest channel gain to it for\(k\)=1:\(K\)do for\(l\)=1:\(L\)do  find \(\xi_{kl}\) \(l_{k}=arg\ max\ l_{\in\{1,\ldotsFigure 2: Flowchart of the proposed algorithm. ## 4 Results and Discussion

The proposed cell-free network with an expanded IoT framework is modelled in a MATLAB simulation environment [55]. The results of the performance evaluation are presented in this section. The simulation model considers deployment of large number of APs in a given area of 1 km \(\times\) 1 km to give service to massive user nodes. The APs are installed with uniform linear array. The size of the array is \(N=4\). The model considers a 3 GPP microcell urban scenario with propagation parameters listed in Table 2. In the proposed model, an interference-aware scheduling scheme is presented whose performance evaluation is also carried out under different conditions. The performance parameters used for the evaluation of the proposed model include the number of connected nodes, number of APs, node locations, pilot length and spectral efficiency. The impact of different precoding schemes under different network operations on the performance is also investigated. A data or message flow diagram is presented in Figure 3.

The performance of the proposed cell-free IoT network is quantified in Figure 4 for spectral efficiency achieved by the IoT nodes. The four precoding schemes are used under different cell-free operations. LPMMSE and MR precoding are used for distributed operation while PRZF and PMMSE are used for centralized operation. The comparison is evaluated in Figure 4 in which the cumulative distribution function (CDF) of the spectral efficiency in the downlink operation is plotted. The spectral efficiency obtained is 2.949 bits/s/Hz for MR precoding and 8.592 bits/s/Hz for scalable LPMMSE precoding. For the centralized operation, the PRZF and PMMSE precoding have similar performance, which gives 9.207 bits/s/Hz downlink spectral efficiency. In the proposed model, the scheduling of nodes and serving APs is achieved using the proposed scheme, which takes into account the interference caused by the neighbouring nodes as well as the interfering APs. The CDF is obtained for the downlink operation to assess the performance of the proposed algorithm in Figure 5 for the precoding schemes defined in Section 2. The incorporation of proposed scheduling method, which facilitates optimal association of sensor nodes and the APs results in improved system performance. It \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Parameters** & **Value** & **Parameters** & **Value** \\ \hline \(N\) & 4 & \(L\) & 50 \\ \(K\) & 40 & \(\alpha\) & 3.76 m \\ \(\tau_{p}\) & 10 & \(\eta_{p}\) & 100 mW \\ \(\tau_{c}\) & 200 & \(\eta_{k}\) & 100 mW \\ \(B\) & 20 MHz & \(\sigma^{2}\) & \(-94\) dBm \\ \(B_{c}\) & 100 KHz & \(T_{c}\) & 1 ms \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Simulation parameters. Figure 3: Illustration of data or message flow in the proposed network model. has been observed that centralized precoding outperforms the LPMMSE and MR precoding achieving 18.9% improvement in achieved spectral efficiency with the proposed scheduling. The communication model with proposed scheduling is compared with two other system models, one that is not incorporating any user-AP association and another that is using random scheduling to assign the nodes with the APs.