Because this paper conducted experiments in real world apartments to study the impact of interference on wireless networks, the observations it found should be more applicable to real-world environments compared with the study using simulations. The drawback of using real homes is that it is time-consuming and costly. Thus, the paper can only collect data from limited number of homes and time periods. Nonetheless, the conclusions and findings of this paper are still very valuable. For example, it found that the commonly-held assumption that channel 26 will be open is not true in the real-world situation. Only careful study on real world like this paper can have such kind of findings.
The methods of data analysis in this paper were well-considered. For example, to investigate spectrum usage change with time, it computed the standard deviation of occupancy using various time periods: day-to-day, hour-to-hour and every 5 minutes. By considering both long and short time scale, the conclusion that there is significant variability overtime for spectrum occupancy was supported much more strongly.
Although, overall the quality of analysis in this paper is very good, some aspects are not fully investigated. For example, in the analysis of Wi-Fi interference, the paper claimed there are other non-negligible interferences apart from Wi-Fi, but it didn’t investigated what they are concretely. It should investigated why the situations in apartment 4 and apartment 5 are different from others as indicated in Figure 5 of the paper.
This paper had many insightful findings about HAN, a natural extension and improvement of this paper is to address how we solve the problems found and apply the knowledge learned such as HAN design that can decrease the interferences of Wi-Fi and other sources and the combination of channel diversity and transmission power control.