A Prototype Orthogonal Vertical Beamforming for Indoor Wireless Communications Paleerat Wongchampa Department of Electronics Engineering Technology, College of Industrial Technology, King Mongkut’s University of Technology North Bangkok, Thailand Email: paleerat.w@cit.kmutnb.ac.th Abstract —The concept of Orthogonal Vertical Beamforming (OVB) is proposed in this paper to eliminate interference when users remain at the same angle in the horizontal plane but are positioned at different distances. This orthogonal property helps systems avoid interference in the vertical direction of the mainbeam. A fully constructed prototype tested in a real indoor environment validates the proposed concept, revealing that the proposed OVB provides higher Signal Interference plus Noise Ratio (SINR) and Packet Error Rate (PER) in the vertical plane than conventional vertical beamforming and Orthogonal Beamforming. Index Terms—Beamforming, reduce interference, orthogonal, smart antenna, multiple antennas I. INTRODUCTION Indoor wireless communication is mainly accomplished through the use of a wireless local area network (WLANs). WLANs have become highly popular [1]-[3] because of the lots of benefits they provide. WLANs not only provide us with the ease and flexibility to utilize them, but they may also be used to link in-home or office computer networks, and wireless devices have evolved over the years. In the current generation, these technologies have become an essential part of our daily lives, and the significance of wireless communication cannot be overstated. As the number of personal wireless devices increases, so would the problem of interference, increased data traffic, and capacity as the RF spectrum gets more overcrowded. Developing interference mitigation technologies and appropriate radio resource allocation technology to improve communication reliability and enable high data rate applications is essential in such an environment. One technique is to use several antennas 2–4 to use the spatial domain of the communication channel. Multiple antenna systems are important in improving wireless system spectral efficiency [4]-[6]. To overcome the problem of interference, the combination of multiple antenna arrays with beamforming technologies assists in suppressing interfering signals and receiving signals from the desirable ones. The fundamental principle of Manuscript received April 1, 2021; revised October 15, 2021. This work was supported by College of Industrial Technology, King Mongkut’s University of Technology North Bangkok, Thailand. Corresponding author email: paleerat.w@cit.kmutnb.ac.th doi:10.12720/jcm.16.11.516-521 beamforming is the cancellation of interfering signals by creating signals that produce constructive interference at appropriate angles and destructive interference at other angles. According to the research reported in [7] the Orthogonal Beamforming (OBFM) primarily evaluated the gain provided by the horizontal plane while ignoring to include the gain provided by the vertical plane shown in Fig. 1. Figs. 1(a) and (b) depict the top and side views of a situation in which users are pointing in the same direction (angle in horizontal plane) but are separated by a distance. In this scenario, the proposed OBFM is inefficient since it can only produce one horizontal beam to a single user. The conventional vertical beamforming approach [8], [9] has a low Signal to Interference plus Noise Ratio (SINR) due to interference from other users, as seen in Fig. 2. As a result, this paper proposes Orthogonal Vertical Beamforming (OVB) to eliminate interference in an indoor vertical plane environment. The following is the rest of this paper: Section II follows the brief introduction by describing a short system model of the OVB. Then, in Section III, experimental results in an orthogonal vertical beamforming prototype are carried out to demonstrate the performance of the suggested idea. The article is finally concluded in Section IV. 0 degrees 90 degrees User 1 User 2 User 3 User 1 User 2 User 3 Horizontal Plane (a) (b) Fig. 1. Top view (a) and side view (b) in the horizontal beamforming. User 1 User 2 User 3 Horizontal Plane Interferences Fig. 2. Conventional vertical beamforming. 516 ©2021 Journal of Communications Journal of Communications Vol. 16, No. 11, November 2021