The advent of fifth-generation (5G) systems and their mechanics have introduced an unconventional frequency spectrum of high bandwidth with most falling under the millimeter wave (mmWave) spectrum. The benefit of adopting these bands of the frequency spectrum is two-fold. First, most of these bands appear to be unutilized and they are free, thus suggesting the absence of interference from other technologies. Second, the availability of a larger bandwidth offers higher data rates for all users, as there are higher numbers of users who are connected in a small geographical area, which is also stated as the Internet of Things (IoT). Nevertheless, high-frequency band poses several challenges in terms of coverage area limitations, signal attenuation, path and penetration losses, as well as scattering. Additionally, mmWave signal bands are susceptible to blockage from buildings and other structures, particularly in higher-density urban areas. Identifying the channel performance at a given frequency is indeed necessary to optimize communication efficiency between the transmitter and receiver. Therefore, this paper investigated the potential ability of mmWave path loss models, such as floating intercept (FI) and close-in (CI), based on real measurements gathered from urban microcell outdoor environments at 38 GHz conducted at the Universiti Teknologi Malaysia (UTM), Kuala Lumpur campus. The measurement data were obtained by using a narrow band mmWave channel sounder equipped with a steerable direction horn antenna. It investigated the potential of the network for outdoor scenarios of line-of-sight (LOS) and non-line-of-sight (NLOS) with both schemes of co- (vertical-vertical) and cross (vertical-horizontal) polarization. The parameters were selected to reflect the performance and the variances with other schemes, such as average users cell throughput, throughput of users that are at cell-edges, fairness index, and spectral efficiency. The outcomes were examined for various antenna configurations as well as at different channel bandwidths to prove the enhancement of overall network performance. This work showed that the CI path loss model predicted greater network performance for the LOS condition, and also estimated significant outcomes for the NLOS environment. The outputs proved that the FI path loss model, particularly for V-V antenna polarization, gave system simulation results that were unsuitable for the NLOS scenario.

The current propagation models used for frequency bands less than 6 GHz are not appropriate and cannot be applied for path loss modeling and channel characteristics for frequency bands above 6 GHz millimeter wave (mmWave) bands, due to the difference of signal propagation characteristics between existing frequency bands and mmWave frequency bands. Thus, extensive studies on channel characterization and path loss modeling are required to develop a general and appropriate channel model that can be suitable for a wide range of mmWave frequency bands in its modeling parameter. This paper presents a study of well-known channel models for an indoor environment on the 4.5, 28, and 38 GHz frequency bands. A new path loss model is proposed for the 28 GHz and 38 GHz frequency bands. Measurements for the indoor line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios were taken every meter over a separation distance of 23 m between the TX and RX antenna locations to compare the well-known and the new large-scale generic path loss models. This measurement was conducted in a new wireless communication center WCC block P15a at Universiti Teknologi Malaysia UTM Johor, Malaysia, and the results were analyzed based on the well-known and proposed path loss models for single-frequency and multifrequency models and for directional and omnidirectional path loss models. Results show that the large-scale path loss over distance could be modeled better with good accuracy by using the simple proposed model with one parameter path loss exponent PLE (n) that is physically based to the transmitter power, rather than using the well-known models that have no physical base to the transmitted power, more complications (require more parameters), and lack of anticipation when explaining model parameters. The PLE values for the LOS scenario were 0.92, 0.90, and 1.07 for the V-V, V-H, and V-Omni antenna polarizations, respectively, at the 28 GHz frequency and were 2.30, 2.24, and 2.40 for the V-V, V-H, and V-Omni antenna polarizations, respectively, at the 38 GHz frequency.

The recent advancement in the 5G wireless technologies is demanding higher bandwidth, which is a challenging task to fulfill with the existing frequency spectrum i.e. below 6 GHz. It forces operators and researchers to go for higher frequency millimeter-wave (mm-wave) spectrum in order to achieve greater bandwidth. Enabling mm-wave, however, will come with various path loss, scattering, fading, coverage limitation, penetration loss and various different signal attenuation issues. Optimizing the propagation path is much essential in order to identify the behavior of channel response of the wireless channel before it is implemented in the real-world scenario. In this paper, we have analyzed the potential ability of mm-wave frequency band such as 28 and 73 GHz and compare our results with the existing 2.14 GHz LTE-A frequency band. We utilize the most current potential Alpha Beta Gama (ABG) propagation path loss model for designing urban microcell line of sight (LOS) scenario. We investigate the network performance by estimating average user throughput, average cell throughput, cell-edge user's throughput, peak user throughput, spectral efficiency and fairness index with respect to different user's capacity. The results express the significant improvement in spectrum efficiency of up to 95% for 28 GHz and 180% for 73 GHz is achieved in comparison with 2.14 GHz. It results also show that the 28 and 73 GHz frequency band is able to deliver up to 80 and 170% of enormous improvement in average cell throughput respectively as compared to currently LTE-A frequency band.

In order to achieve higher data rate for the next-generation 5G communication network, utilization of millimeter waves (mm-waves) frequency bands is the major advancement for getting the higher bandwidth. Despite the fact, various challenges are coming to light such as propagation loss, time delay, fading, and scattering losses, when radio signals are propagated at mm-waves frequencies. Propagation parameters optimization is crucial for achieving better performance for the given wireless network. In this paper, we will characterize the propagation channel and investigate the potential ability of 28 GHz and 38 GHz mm-wave frequency bands for two 5G currently most prospective propagation path loss model such as Close-in (CI) and Alpha-Beta-Gamma (ABG). Our results have been evaluated by estimating the average user throughput, cell-edge user throughput, average cell throughput, spectral efficiency and fairness index with respect to a different number of users in a cell. The results show that the 38 GHz frequency model giving more throughput performance as compared to 28 GHz frequency band due to higher bandwidth availability on a higher frequency. Furthermore, in this paper, it is quantitatively proved that due to using only one model parameter [i.e. path loss exponent (PLE)] in CI path loss model, it performs significantly better in comparison with ABG path loss model.