# Evaluating 60 GHz FWA Deployments for Urban and Rural Environments in Belgium
## 3 Evaluation Framework
### Link Budget and Channel Modelling  
The considered system operates in the V-Band, particularly in channels 1-6 for the IEEE 802.11 ad standard [12], with a bandwidth of 2.16 GHz per channel. One channel is used for the access network (CPE-EN), while up to four channels are considered for the backhaul network, depending on capacity requirements. Table 3 lists the parameters utilised by the transceiver to calculate the link budget parameters in the network. Detailed realistic 3D antenna gains and beamforming codes implemented are modelled based on specific hardware design [66]. In addition, Table 4 defines the required signal-to-noise ratios (SNR) used to achieve the requested bit rates for the spirit module from confidential information provided by Pharrowtech partner [66]. All CPE nodes should support at least 1 Gbps (SNR = 3.5 dB), while the backhaul links at least 2.5 Gbps (SNR = 7.5 dB). Higher modulation schemes are used to improve link usage. The 60 GHz channel model is based on actual measurements in this band [67]. The path loss attenuation is modelled as follows:  
\[PL(\mathrm{d})[\mathrm{dB}]=PL_{\mathrm{p}}+PL_{\mathrm{refl}}+PL_{\mathrm{rain }}+PL_{\mathrm{veg}} \tag{1}\]  
where \(PL_{\mathrm{p}}\) is the loss due to propagation, \(PL_{\mathrm{refl}}\) is the reflection loss, \(PL_{\mathrm{rain}}\) is the loss due to the rain and \(PL_{\mathrm{veg}}\) the excess loss due to vegetation. \[PL_{\mathrm{p}}[\mathrm{dB}]=PL_{0}+10\eta\log_{10}(d)+\chi \tag{2}\] \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Unit** & **Value** \\ \hline Frequency Band & GHz & 60 (57–71) \\ Channel bandwidth & GHz & 2.16 \\ TDD duty cycle DL & \% & 75 \\ TDD duty cycle UL & \% & 25 \\ Spatial duty cycle & \% & 15 \\ TX RF Paths & \# & 32 \\ TX Patches/Path & \# & 2 \\ TX Patch Gain & dBi & 5 \\ TX Subarray Gain & dBi & 2 \\ TX Total antenna Gain & dBi & 25.1 \\ Total radiated power & dBm & 39 \\ TX array feed loss & dB & 2.5 \\ Receiver noise figure & dB & 10.2 \\ Implementation Margin & dB & 4 \\ Azimuth Steering & \(\circ\) & \(+\)\(-\)45 \\ Elevation Steering & \(\circ\) & \(+\)\(-\)30 \\ Beam Codebook size & \# & 1024 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Transceiver network parameters for the simulation. For \(PL_{\text{P}}\), \(PL_{\text{0}}\) is the reference path loss at 1 m (\(PL_{\text{0}}\) = 71 dB), \(\eta\) is the the path loss exponent (\(\eta\) = 1.78) and \(\chi\) is a lognormal variable representing shadowing fading with \(\sigma\) = 3.5 dB. \(PL_{\text{refl}}\) is the attenuation due to the reflection of the multi-bouncing ray tracing. We implement a two bouncing ray tracing method, where each ray launches a ray every 5 degrees, looking for an intersection in a circumference with a 10 m radius. Up to two wall bounces are accounted until a ray is discarded [68]. We select two types of walls: bricks and concrete, representing the material of the reflecting wall. We assume that concrete is for new houses with a probability of appearance of 30%, while 70% of the houses are considered to be made of brick [6]. The reflection loss depends on the bouncing angle \(\alpha\) and the type of material and is described in Equation (3). \[PL_{\text{refl}}[\text{dB}]=\left\{ \begin{matrix}15(1-\frac{\alpha}{50})&\text {Brick}&70\%\\ 8(1-\frac{\alpha}{50})&\text{Concrete}&30\%\end{matrix} \right. \tag{3}\]  
The \(PL_{\text{rain}}\) is the attenuation due to rain, and it depends on the area where it is used. For Belgium, a 0.1% outage probability is found for a rain intensity of 10 mm/h, which is considered light rain. For heavy rain, a 0.001% outage probability corresponds to 50 mm/h [69]. The rain attenuation measurements we presented in [70] for light rain are consistent with the values reported in the ITU-P 530-16 838 [71; 72; 73]. In addition, the heavy rain values tend to differ in different regions; the attenuation value for western Europe is reported to be slightly higher than in other areas, particularly in fixed wireless links [74].