IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 14, 2015 735 Large-Scale Fading Characteristics of Indoor Channel at 45-GHz Band Jin Zhu, Haiming Wang, Member, IEEE, and Wei Hong, Fellow, IEEE Abstract—The channel measurement and modeling of large- scale fading characteristics of 45-GHz band in three typical indoor environments are investigated. An automatic measurement system owning a sufficient dynamic range is designed to overcome the prominent attenuation in 45-GHz band. After conducting exten- sive measurements, large-scale fading characteristics including path-loss exponent, cross-polarization discrimination ratio, and standard deviation of shadow fading are obtained and compared in different scenario setups. Goodness-of-fit test is applied to val- idate whether the assumed log-normal distribution can describe the shadow fading characteristics. Index Terms—45 GHz, indoor channel, large-scale fading, shadow fading. I. INTRODUCTION R EQUIREMENTS for higher quality and better user expe- rience lead to the booming of various novel wireless com- munication technologies possessing higher throughput. More- over, with the rapid advances of CMOS radio frequency inte- grated circuit technologies and low-cost circuit integration so- lutions, millimeter-wave (mmWave) wireless communication technologies have attracted great interest from academia and in- dustry. As the conventional techniques are limited in the lower frequency bands, e.g. 2.4 and 5 GHz, the mmWave frequency band is considered to be a promising candidate for the new-gen- eration wireless local access network (WLAN) systems due to its availability of unused wide bandwidth. IEEE 802.11aj, which operates on 45-GHz band with bandwidth up to 5.9 GHz, was proposed in 2012 [1]. One of the biggest challenges for the system design of mmWave wireless communications is high propagation loss due to high frequency. Channel measurements on wireless communication systems, such as IEEE 802.15.3c/802.11ad and 5G cellular, include, but are not limited to, [2]–[6]. In this letter, to get a detailed insight into large-scale fading characteristics for the new frequency band, a large amount of measurements in different scenarios have been conducted in three typical environments including a conference room, a living room, and a cubicle office. Using a classical path-loss (PL) model, the fading characteristics of 45-GHz band including PL exponent, Manuscript received October 13, 2014; accepted November 25, 2014. Date of publication December 05, 2014; date of current version March 02, 2015. This work was supported in part by the 973 Program of China under Grant No. 2013CB329002, the NSF of China under Grant No. 61132003, and the NSF of Jiangsu Province of China under Grants BK2011019 and BK20130631. The authors are with the State Key Laboratory of Millimeter Waves, South- east University, Nanjing 210096, China (e-mail: hmwang@seu.edu.cn). Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LAWP.2014.2377952 Fig. 1. Automatic channel measurement setup. TABLE I PARAMETERS OF THREE ANTENNAS cross-polarization discrimination ratio (XPR), and standard deviation of shadow fading are then obtained. II. CHANNEL MEASUREMENT CAMPAIGN A. Measurement Equipment and Setup As shown in Fig. 1, a computer is used to not only control the rotary table via the RS-232 port, but also control the signal generator and the vector network analyzer (VNA) using the LAN. An Agilent signal generator E8257D is used to transmit continuous wave signal in power of 10 dBm. Then, the received signal is recorded by an Agilent VNA N5245A. The signal is transmitted from the independent signal generator instead of the VNA to avoid the large cable loss due to the long cable. Therefore, the dynamic range of this channel measurement system can be increased using such a configuration. Three types of linearly polarized antennas including the horn antenna, the open ended waveguide (OEW) antenna, and the V-dipole an- tenna (VDA) [7], with radiation characteristics listed in Table I, are used in the channel measurements. Both copolarization and cross-polarization measurements are conducted. Before the practical channel measurement, the signal generator is directly connected to the VNA to obtain calibration data. In the line-of-sight (LoS) scenario, the transmit/receive (Tx/Rx) antennas are both rotated to be aligned to each other according to its specific three-dimensional coordinates. In the non-LoS (NLoS) scenario, in conference and living rooms, the 1536-1225 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.