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Radiowave Propagation
Published in Indrakshi Dey, Propagation Modeling for Wireless Communications, 2022
Some unwanted factors like interference, noise, inter-symbol interference (ISI), and intermodulation products also degrade the system performance of wireless radio communication. Introduction of MIMO systems and spatial reuse of radio spectrum have resulted in co-channel interference. When two transmitters separated by a certain distance transmit over identical carrier frequency, co-channel interference will result. Both the desired and the interfering signals may travel to the receiver through the same or different paths; in the latter case, the two signals fade independently with or without identical distributions. Impact of co-channel interference can be measured through the signal to interference-plus-noise ratio (SINR).
Intelligent O&M on an Intent-Driven Campus Network
Published in Ningguo Shen, Bin Yu, Mingxiang Huang, Hailin Xu, Campus Network Architectures and Technologies, 2021
Ningguo Shen, Bin Yu, Mingxiang Huang, Hailin Xu
A campus network has multiple types of service nodes and network nodes, and each node has many indicators. These nodes and indicators are associated one another, resulting in complex and changeable network fault patterns. In some cases, the same fault symptom may have different root causes. For example, a user authentication failure on a Wi-Fi network may be caused by a weak Wi-Fi signal or a certificate error. In contrast, the same root cause may contribute to different fault symptoms. For example, co-channel interference may cause poor bandwidth experience and/or high channel usage on a Wi-Fi network. As a result, a data association system has been designed based on large amounts of network O&M data to identify the association and causal relationship between different service nodes from the O&M data relationship diagram. This helps O&M personnel locate the root causes of faults. Figure 7.21 shows the correlated root cause analysis process.
Channel Impairments
Published in Mário Marques da Silva, Cable and Wireless Networks, 2018
Co-channel interference occurs when two different communications using the same channel interfere with each other. In a cellular environment, this occurs when a communication is interfered by another communication being transmitted in the same carrier frequency but typically coming from an adjacent cell. In cellular networks using TDMA/FDMA, this type of interference can be mitigated by avoiding the use of the same frequency bands in adjacent cells, introducing the concept of a frequency reuse factor higher than 1.† In CDMA networks, this kind of interference is always present because the whole spectrum is typically reused in all cells, making the reuse factor as 1. The reuse factor refers to the reutilization of the same frequency bands in adjacent cellular networks. In Figure 3.21a, different letters in different cells mean that different sets of frequency bands are utilized in different cells. In this case, because each group of seven cells use different frequency bands, and the overlapping of frequency bands is only reutilized in another adjacent group of seven cells, the reuse factor is 7.
Interference Cancellation in Wireless Communications: Past, Present, and Future
Published in IETE Journal of Education, 2022
S. M. Zafaruddin, Pranay Bhardwaj
Generally, multiple users accessing the same frequency band can create interference among them. From the beginning, orthogonal multiple access techniques have been instrumental to avoid multi-user interference. Frequency division multiple access (FDMA) is a simple technique that allocates non-overlapping channels to each user [4]. However, the non-linearity of power amplifiers to generate FDMA signals causes the inter-modulation effect giving signals of undesired frequencies. The concept of frequency reuse in a cellular wireless system increases the number of users in a frequency band; however, with a cost of co-channel interference [10]. The cognitive radio is another potential technology to limit the spectrum scarcity by allowing secondary users to occupy the idle channels of primary users without increasing the interference of thenetwork.
Resource allocation of offshore ships' communication system based on D2D technology
Published in Systems Science & Control Engineering, 2022
Yu Wang, Jiaming Zhang, Shuo Xu, Baihai Zhang
However, in the real environment, when D2D communication device pairs coexist with cellular network users which is communicating with the base station, the communication between them will inevitably cause mutual interference (Feng et al., 2013); and as the number of D2D communication device pairs in the network increases, D2D communication equipment pairs will reuse the spectrum resources of cellular network users due to the lack of spectrum resources. This process will inevitably cause co-frequency interference between D2D users and cellular users. If there is no corresponding coordination strategy, serious co-channel interference will greatly reduce the communication performance of the communication system.
Performance Evaluation of Co-Channel Interference on Wireless Networks
Published in Journal of Computer Information Systems, 2022
Joong-Lyul Lee, Joobum Kim, Myungjae Kwak
In recent years, numerous Internet of Things (IoT) devices are being used in our real life due to the development of wireless technology. For example, a smart light bulb, a smart home assistant, a smart wearable device, a smart door lock, a smart TV, a smart refrigerator, a smart vacuum cleaner, etc. are used in a smart home. These numerous IoT devices use the 2.4 GHz or 5 GHz frequency in which is an unlicensed Industrial, Scientific, and Medical (ISM) spectrum under the Federal Communications Commission (FCC). In addition, microwave ovens, cordless phones, Bluetooth devices, wireless security cameras, and ZigBee devices also used the ISM band. The IEEE 802.11 standard use in 2.4 GHz, 5 GHz, and 6 GHz frequency ranges. The Wireless LAN (WLAN) in the 2.4 GHz band provides 11 channels (1–11), each 20 MHz wide. Many of these devices cannot avoid the co-channel interference (CCI) phenomenon caused by using the same frequency and the adjacent channel interference (ACI) phenomenon caused by using adjacent frequencies. Even though it is recommended to use channels 1, 6, and 11 in order to avoid these channel interference phenomena, the interference phenomenon is inevitably experienced due to an increase in the number of IoT devices. Currently, new WLAN technology (IEEE 802.11 ac/ax) have been proposed to avoid these issues. However, this topic is still an ongoing issue as interference represents significant network performance degradation in WLAN, as many devices still use 2.4 GHz. Therefore, in this paper, we compare and analyze the CCI phenomenon with the simulation results in the ns-3 simulator and the real experiment results, and analyze how this phenomenon affects the network performance at the TCP layer.