## 6 Result and Analysis
### Cost and Power Consumption Against Data Throughput Analysis  
The second part of this paper analyzes the cost and power consumption against the data throughput of the proposed system. The proposed system is compared with two other systems as was previously detailed in Section 4. Before discussion of the results, the simulation environment is explained. The system model used in this simulation is adopted from [29]. Circular LED deployment is used to conserve the energy. Additionally, since LEDs are used, they use 85% less energy and last 20 times as long as traditional incandescent light. This simulation was done for a four-year period with an average LED lifespan of 40,000 h, after which, the LED was replaced.  
The first simulation is based on the cost and power consumption of the SPU. There are currently many high-quality SPUs available in the market, which are specifically designed for telecommunication purposes. For this simulation, a comparison of the different products of Texas instruments C6000 series DSP boards is done. The list of the DSP boards used is provided in Table 2. From Figure 6, it can be seen that as the computational power of the DSP increased the device cost also increased. The same trend can also be seen with power consumption and cost. Since the DSP industry is now moving towards efficient low power boards, the prices mentioned here are estimated based on this trend. It is expected that as power-efficient boards are introduced in the market, their device and power cost will decrease. For simulation purposes, a basic DSP board capable of handling the proposed system according to its specifications was chosen [34].  
A comparison was made individually between device cost, power cost, and total against data throughput. Figure 7 shows the device cost against the data throughput for each system as described in Section 4. It can be seen that the device cost for the proposed system is initially high but as  
Figure 6: Simulated average device cost and power consumption cost over data throughput for different SPUs (Table 2).  
time passes, the system becomes cheaper due to low maintenance costs. The maintenance cost in this simulation includes replacement of light bulbs and hardware upgrades for the Wi-Fi device. Significantly, there would be no hardware upgrade needed for a VLC system as it would be able to handle the required data throughput for an average smart home for at least the next five years.  
Figure 8 shows the power cost against the data throughput for each system as described in Section 4. From the figure, it can be seen that systems 1 and 2 are expensive as they draw more power against data throughput. In comparison, due to the availability of a power-efficient DSP board, the power cost of the proposed system against data throughput is significantly less, which results in an overall low total cost when compared with that of the other two systems.  
The total cost against data throughput is shown in Figure 9. It can be seen that the initial cost of the proposed system is higher than that of the other two systems, but as they approach the four-year mark, the proposed system turns out to be more cost- and power-effective. The purpose of this result is to illustrate a recurring pattern in the energy industry and resolve any confusion an average person may have on whether we should invest in VLC systems or not. The same trend was seen when LED lights were first introduced. The initial cost was much higher than that of the traditional incandescent lights, but with time, the savings owing to the LED lights were much higher than those for traditional incandescent lights. This has led to LEDs becoming more prominent than their traditional counterparts.  
Figure 8: Power consumption cost comparison of architecture 1 for all three systems.  
Figure 7: Device cost comparison of architecture 1 for all three systems.