The impact of directional antenna use and restriction of end-to-end delay on different performance metrics in wireless sensor networks

Wireless Sensor Networks (WSN), which have an important place in terms of wireless communication and the internet of things (IoT), are still up-to-date due to their various advantages and allow new potential workspace areas for the future. Due to limited battery life, optimization and energy efficiency are very important in the WSN. Although the current WSN can be used in many different areas, updates are needed for some special cases. The first of the special cases that are dealt with in this thesis is to be able to communicate with the low delay specified in the Ultra-Reliable Low- Latency Communication (URLLC) architecture, thus ensuring data freshness. To achieve the aforementioned situation in this thesis, it is recommended to restrict the delay or end-to-end (E2E) delay that is required for transmitting the data from each generator sensor to the base station. The second special case discussed in this thesis is to increase the performance for the places where the omnidirectional antennas in the WSN are insufficient. Since it is desired for a node to communicate with many nodes around it, an omnidirectional antenna is generally preferred as the antenna type for the WSN. On the other hand, the low bit error rates (BER) that are achieved in other communication systems cannot be achieved for this antenna type. In addition, due to the use of omnidirectional antennas, methods for dealing with interference between different nodes in the WSN are more limited and inefficient. Furthermore, unnecessary energy loss occurs due to communication within all directions for this antenna type. In order to overcome these problems in the second special case, the use of directional antennas is encouraged. Thanks to the use of the directional antenna, low bit error rates that cannot be reached in cases with omnidirectional antennas are achieved. Using a directional antenna also allows us to create more efficient methods by providing different working opportunities to get rid of the effect of interference. Limiting the E2E delay at this stage is also beneficial for creating more efficient methods. In addition to these, energy efficiency is also increased thanks to the possibility of communication in only a certain direction. Considering all these mentioned situations, four different studies are carried out for this thesis: In the first study, the effect of restricting the delay on the lifetime is examined while using only omnidirectional antennas. In this study, it is seen that restricting the delay has a negative effect on the lifetime. Furthermore, it is observed that increasing the number of nodes in the WSN also increases the lifetime. The second study examines the effect of restricting E2E delay on the lifetime and average BER. In the related study, the advantages of directional antennas are highlighted by using both omnidirectional and directional antennas for each scenario. In this study, it is observed that restricting the E2E delay not only reduces lifetime but also increases average BER. In addition, a large increase in the lifetime and a large decrease in average BER is observed while using directional antennas. In the third study, only directional antennas are used, but two different analyses are carried out. In the first analysis, the minimum E2E delay required for communication with a particular BER is calculated, considering the density of the sensor network. The second analysis examines the impact of restricting E2E delay and BER on the lifetime. In both analyses, very low BER values can be used for the restriction by taking advantage of the benefits provided by the directional antenna. As a result of this study, it is seen that as the number of nodes in the WSN increases, the minimum E2E delay required to reach a certain BER decreases. Additionally, it is seen that restricting BER decreases the lifetime like the E2E delay restriction. In the last study, considering the advantages of using directional antennas and limiting the E2E delay, two different methods are discussed to prevent interference. For the first of these methods, Time Division Multiple Access (TDMA), which is currently a popular method, is preferred. The second method is the Interference Preventing Model (IPM), which is designed for this thesis and makes more use of the advantages of directional antennas so that efficiency can be increased. Performance evaluation is made by comparing the bit rates and lifetimes that are calculated by using both methods. Accordingly, a higher bit rate is achieved by using IPM compared to TDMA. Moreover, in cases where IPM has the same bit rate as TDMA, there is an increase in lifetime.