Cellular Communications Coverage Prediction Techniques: A Survey and Comparison
A lot of effort and time is utilized in the planning and building of the cellular wireless networks to use minimum infrastructural components to provide the best network coverage as well as delivery of quality of service. Generally, path loss models are used for the prediction of wireless network coverage. Therefore, detailed knowledge of the appropriate path loss model suitable for the proposed geographical area is needed to determine the coverage quality of any wireless network design.
... work design. However, to the best of our knowledge, despite the importance of path loss models, as used for the prediction of wireless network coverage, there doesn't exist any comprehensive survey in this field. Therefore, the purpose of this paper is to survey the existing techniques and mechanisms which can be addressed in this domain. Briefly, the contributions of this paper are: (1) providing a comprehensive and up to date survey of the various network coverage prediction techniques, indicating the different frequency ranges the models were developed, (2) the different suitable terrains for each of the model and the best suit mobile generation were presented, and lastly, (3) providing comparative analysis to aid the planning and implementation of the cellular networks. INDEX TERMS Path loss model, prediction, wireless, propagation scenarios, mobile generations, signal. 113052 This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ VOLUME 8, 2020 O. O. Erunkulu et al.: Cellular Communications Coverage Prediction Techniques The effects of the propagated signals are usually mathematically represented. In other words, the channel model addresses the medium in which the signal is transmitted. On the other hand, propagation models predict the distance the signal will travel before attenuation, which is the coverage area of the transmitted signal. The propagation models require the properties of the proposed geographical area to determine the coverage quality of any wireless network design. Various researches on channel prediction techniques had been carried out - for various wireless channel systems such as multiple input and multiple output systems (MIMO) -. Reference  surveyed wireless channel standardized models and radio propagation models for MIMO systems while  presented the preliminary outcomes of extensive research on mmWave massive MIMO. Some of the models discussed are not only used for cellular communication but other wireless systems such as unmanned aerial vehicle (UAV) , , digital terrestrial television (DTT) system , Digital Video Broadcasting -Terrestrial DVB-T , . Conventionally, the cellular coverage map is built by service providers using a time consuming and an expensive campaign known as a drive-test. The Radio Frequency (RF) parameters are subject to various tuning process to determine the optimum values. According to various researches, the prediction of network coverage areas theoretically, is quite difficult to actualize -  . However, wireless network coverage prediction can be solved mathematically by using computer algorithms (software simulations) and initial assumptions for the planning of any wireless communication networks, and it mathematically estimates the anticipated network characteristics which assist in the design process. The models are expected to be as precise as possible for the easier development of wireless networks  . On the other hand, the frequency bands have been exploited worldwide for various mobile wireless communication infrastructures. As a result of this, organizations were set up to govern the worldwide allocation of spectrum for the 5G networks systems. These organizations to provide the guidelines are the International Telecommunication Union for Radiocommunication sector (ITU-R)  and the World Radio Conference (WRC-15)  . Presently, all wireless systems make use of spectrum in the range 300MHz to 3GHz band while the future communication network (5G and so on) will use the millimeter wave (mmWave) band as the channel. These frequency bands are known to have different channel propagation characteristic that affects signal transmission. Therefore, the accurate selection of the propagation model for different frequency bands and terrains is essential. In this paper, a comprehensive comparative and up to date study of the various network coverage prediction techniques at different frequency ranges, the best suit mobile generation, as well as the suitable terrains for each of the models was carried out. It had also provided a comparative analysis to aid the planning and implementation of the cellular networks. The paper focuses on the propagation models for large-scale fading in mobile communication. The rest of this paper is organized as follows: Section II highlights related work. Section III discusses the propagation phenomena of wireless propagation. In Section IV, the various propagation models used for coverage prediction for cellular communications are discussed. In Section V, the classification of the models is presented. Section VI discussed the emerging technology, and finally, conclusions are drawn in Section VII. II. RELATED WORK Over the years, many studies have investigated and surveyed the propagation models for various frequency bands in different environments (indoor and outdoor) and scenarios (line of sight and non-line of sight). Most of the surveys done had focused mainly on a few PL models. Prior research had focused on models applicable to one or two of the cellular communication networks. Table 1 presents a comparison of a few surveyed and reviewed research work on PL models. III. PROPAGATION PHENOMENA The mechanism for wireless propagation is quite complicated and diverse. Signals are not bonded to any physical conductor or cable like the case of wired transmission; instead, it makes use of EM wave, which is an unguided and unbounded system for the transmission of signals through the medium. Due to the attenuation of the transmitted signals, such phenomena like diffraction, reflections, scattering, refractions, among others, affect the radio wave , as illustrated in Figure 1 .