# An Accurate Probabilistic Model for TVWS Identification
## 3 Prototype Description  
Before describing the prototype and its hardware configuration, it is necessary to review the proposed model. Six blocks are visualized in Figure 3, starting with block 1 that refers to sensing the information of the composite signal \(X(f)\) and the noise signal \(W(f)\) in a separate manner. Block 2 refers to how the samples obtained are processed by each device, i.e., the RF Explorer (RFE) and the Spectrum Analyzer (SA). In block 3, the statistical parameters of each sensed signal are calculated and saved. Block 4 shows the calculated \(P_{fa}\), \(P_{d}\), Missed-detection Probability (\(P_{m}\)), the optimum values for Margin (\(M\)), and Threshold (\(T\)), and other information needed to analyze the UHF-TV spectrum. Block 5 features the Energy Detection (ED) procedure to identify unused channels and PU's presence. Finally, block 6 explains how the output information is represented, detailing the amount of TVWS. Based on this model, the prototype must consider the elements listed in Table 2.  
We designed a Mobile Spectrum Sensing Station (M-SSS) to measure TVWS over the UHF-TV spectrum in the city of Windsor and surroundings. Figure 4a shows that the M-SSS is composed of two Data Acquisition Instruments (DAI), in this case, two RFE installed in parallel, one device connected to a Winegard antenna to collect information of the composite signal \(X(f)\) and the other device with a 50 \(\Omega\) impedance attached and used to sense the noise of the system \(W(f)\). These devices are employed to detect the energy of TV signals over the UHF band. This mobile configuration also has attached a GPS antenna to collect the geographical location for each reading. The M-SSS was designed to be mounted on a vehicle. For this, a supporting structure was assembled using a plastic pipe that fits in a Dodge Grand Caravan vehicle, as shown in Figure 4b-d. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Name** & **Frequencies** & **Channels** & **Partial BW** & **ITU Regions** \\ \hline Band I & 54–72 & 2 to 4 & 18 MHz & R1, R2, R3 \\ Band I (Cont.) & 76–88 & 5 to 6 & 12 MHz & R2 \\ Band III & 174–216 & 7 to 13 & 42 MHz & R1, R2, R3 \\ Band IV & 500–644 & 19 to 42 & 144 MHz & R1, R2, R3 \\ Band V & 644–698 & 43 to 51 & 54 MHz & R1, R2, R3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Bands assigned to the TV broadcasting service, and their corresponding frequencies, channel numbers, partial Bandwidth (BW), and ITU regions. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Ord** & **Device** & **Observation** \\ \hline
1 & External Antenna & Omni, 5 MHz to 1000 MHz range \\
2 & GPS Antenna & USB connector \\
3 & Attached Impedance & 50 \(\Omega\) \\
4 & RF Explorer & Sub 1 G, 240 MHz to 960 MHz range \\
5 & Spectrum Analyzer & High accuracy, 50 kHz–3 GHz \\
6 & Portable Computer & Hardware and software needed \\
7 & External Hard Disk & To save readings and information \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Hardware measurement setup of mobile spectrum sensing station. Figure 3: Chart flow of the proposed model. The antenna and the designed structure, support a speed up to 120 Km/h, verified, and theoretically, a speed up to 144 Km/h, according to data provided by the manufacturer. We used two antennas in our system, a Winegard antenna, model MS-3005 VHF/UHF, 14.9\({}^{\prime}\), and a Global Sat BU-353-S4 USB low consumption GPS antenna. The Winegard MS-3005 is an omnidirectional antenna for receiving VHF and UHF-TV channels. Its frequency range is from 5 MHz to 1000 MHz. It can be installed in indoor or outdoor environments, and we used it to collect information with the deigned M-SSS. Two Winegard antennas were used in this research, one installed on the laboratory roof and another in the M-SSS, both aimed to collect information of the UHF-TV spectrum.