Physical layer simulation study for the co-existence of WLAN standards

by 1981- Kiger, Chad Joseph

Interference is a prime factor that limits the performance of devices within the 2.4 GHz ISM Band. Due to the ISM Band being unlicensed and free to all users, there is an abundance of devices within this frequency range. The three most prominent of such devices used for data communication consist of Bluetooth, Wifi, and Zigbee. In order to understand whether these three protocols can co-exist with each other, a physical layer system model will be developed for each protocol. These systems models will be combined and their interaction with each other examined to determine the effects of the interference under different channel conditions. The channel models will consist of general AWGN and Rayleigh fading channels, along with a sitespecific case involving both Ricean and Rayleigh fading. v Preface In today’s world, there is a growing concern regarding the state of the environment and the effects that pollution will have on the future existence of mankind. Words such as global warming and the ozone layer are predominantly finding their way into the news coverage. Some experts believe that the increase of CO2 in the atmosphere due to the burning of fossil fuels for electricity generation is at the heart of the cause of the depleting ozone layer and the increase in global warming. Because of the diminishing natural resources and the effects that the burning of fossil fuels has on the atmosphere, there is an expanding desire to reduce the dependency on fossil fuels for electricity and focus more on nuclear power. With this shifting of demand stems a need for more efficient processes from current nuclear facilities and also requires for newer plants to be constructed. This results in a revamping of the way in which power plants will be constructed because since the Three Mile Island incident at the Pennsylvania facility in 1979, no new nuclear facilities have been constructed in the United States. Since then there have been major advancements in technology, which could be used to improve the efficiency of these plants. Therefore, not only do the facilities being constructed need to be updated, but also updates to the legacy systems in use in current plants need to be installed. One small area in which these updates need to take place in is in the monitoring and sensing aspect of a nuclear power plant. One convenient and cost effective practice that could be employed would be to shift from a dependency on wired communications to wireless. Everything from accessing the Internet to monitoring reactor conditions could be done using wireless devices that are already developed. This is not only convenient from the aspect of the portability and unobtrusiveness of wireless devices, but it is also cost effective in that running wires in a nuclear power plant can cost up to $2,000 per foot for the required specialized wiring.[1] Two obstacles prevent the widespread use of wireless devices within the confines of a nuclear power plant, and they are security and robustness. Security stems from either information being captured form an outside source, or an outside saboteur introducing his or her own data into different aspects of the facility. Since security deals more with data encryption, it will not be dealt within this report. This report will therefore deal with the robustness or reliability of wireless vi devices. More specifically, the ability for wireless devices to coexist in an environment where there is the presence of other interfering devices. The Nuclear Regulatory Commission (NRC), the governing body over the rules and guidelines imposed upon nuclear power plants, is very interested in this topic of interference caused by wireless devices because in order for new procedures and applications to be installed into nuclear facilities, they must first pass the strict policies of the NRC to allow for safety. The NRC will not authorize the use of wireless devices until they are confident the devices will work properly and not harm other aspects of nuclear power production. This is the task that the NRC has placed upon Oak Ridge National Labs and me in particular, to develop a software tool to be used in conjunction with other methods of determining the coexistence of wireless devices within a nuclear power plant. vii