Experimental Evaluation of the Mobile Radio Channel Capacity in the 2.48 GHz Band

Abstract

Abstract-This paper deals with the effect of the Single-Input Multiple-Output spatial diversity on the OFDM mobile radio signal propagating in an urban channel. From measurements performed in Rio de Janeiro city, Brazil, by using two receiving antennas at diversity, the calculated capacity presented an improvement when compared to the individual one.Index Terms-delay spread, OFDM , SIMO, spatial diversity, urban channel. I. INTRODUCTIONOver the last years, the OFDM (Orthogonal Frequency Division Multiplexing) technique has received special attention to the mobile radio communication in the cellular systems [1][2][3]. Since the available bandwidth is divided into narrower bands, each one experimenting flat fading, this technique presents robustness against time-varying frequency-selective fading. Therefore, such technique offers advantages considering its ability in dealing with high-data-rate transmissions over dispersive channels with low equalization complexity [3]. It is also an efficient solution to operate in Non-LineOf-Sight (NLOS) conditions, normally subject to multipath fading, because it uses cyclic prefix (CP) in order to avoid intersymbol interference. However, the mobility demanded by the users degrades the received signal, worsening it due to the increasing speed which leads a Doppler shift that desynchronizes the OFDM subcarriers, consequently, causing intercarrier interference [4].There have been some solutions to improve final user's delivered signal. Among them is the spatial diversity which is most referred in several studies and it has been used in the reception of the OFDM signal. Ali et al. deals with simulations of blind estimation techniques that exploit the receive antenna diversity [5]; Yagishita et al. [6] studies the effects of diversity in the receiving antenna using Fasterthan-Nyquist (FTN) signaling in a multipath fading channel; Kim et al. [7] analyzes the macrodiversity in LTE-Advanced. However, most of results presented in those studies were obtained from simulations. In this context, this paper provides experimental results for the capacity obtained in a 2.48 GHz band using the spatial diversity in a SIMO (Single-Input Multiple-Output) system. Two branches were used in the reception of a 40 MHz-OFDM signal in the 2.48 MHz band. In order to accomplish it, an urban channel was sounded and the signals from both branches of diversity were

Spatial Diversity Effect on the Experimental Gain of Capacity of the Outdoor Mobile Radio Channel in the 700 MHz Band

“…Based on the measurements performed, this function is experimentally determined for the 760  10 MHz band in both diversity branches: transmitter-receiver 1 (TX-RX1) and transmitter-receiver 2 (TX-RX2). Based on [8,9] if the received signal passes through a filter matched to the transmitted signal (s(t)), the transfer function of the channel is the output of this filter when an impulsive input is used. Then, the filtering process is equivalent to a correlation process (RS), which will result in the instantaneous transfer function h(ti, ) of the channel probed along the delays:…”

Influence of Vegetation on the Outdoor-to-Indoor Mobile Radio Propagation in 700 MHz Band

“…The randomness of the mobile radio channel makes stochastic the transfer function ℎ( , ) defining the behavior of the propagation channel [12]. Based on [12]- [13] if the received signal passes through a filter matched to the transmitted signal (s(t)), the transfer function of the channel is the output of this filter. Therefore, the filtering process is equivalent to a correlation process (Rs), which will result in the instantaneous transfer function h(ti,) of the channel:…”