Sectorised base stations for FSO ground‐to‐train communications

Performance Analysis and Software-Defined Implementation of Real-Time MIMO FSO With Adaptive Switching in GNU Radio Platform

“…where x(t) is the transmitted signal,  is the photodetector responsivity and n(t) is the additive white Gaussian noise (AWGN) with variance 2 . Ii = -lIohi is the received signal intensity from the i th Tx, where Io is received signal intensity for the ideal channel, ℎ is the channel irradiance, l is the link distance, and is the weather-dependent attenuation coefficient (in dB/km) typically 0.43, 42.2 for the clear air and moderate fog, respectively [6]. For an FSO link, the channel gain due to the atmospheric conditions is defined by ℎ = − [23].…”

“…This results in channel impairments and fluctuations of both the amplitude and phase of the propagating optical signals particularly over longer transmission link spans [1]. To overcome this problem, several techniques, including multiple-input multiple-output (MIMO) and relay-assisted FSO systems have been proposed in the literature [4][5][6]. Among the available techniques, MIMO is a reliable technology to realize spatial diversity and to alleviate the atmospheric turbulence induced fading and fog induced attenuation in long distance data transmissions [2].…”

Relayed FSO Links for Ground-to-Train Communications

“…In this section numerical simulation has been performed to evaluate the performance of amplify and forward (AF) relaying system and AF with the combination of 2R regenerator and an OEO regenerator. In all cases, the data rate considered is 10 Gbps with RZ-OOK, λ = 1550 nm, L atm is -17.5 dB/km with a visibility of 800 m and the inter relaying distance is 210 m [9]. The average transmit power P tx is estimated from (9).…”

“…In all cases, the data rate considered is 10 Gbps with RZ-OOK, λ = 1550 nm, L atm is -17.5 dB/km with a visibility of 800 m and the inter relaying distance is 210 m [9]. The average transmit power P tx is estimated from (9). The noise contribution from the background radiation is assessed from (15) and the amplifier noise contribution is estimated from the noise figure given in Table 1.…”

“…Two receivers (Rxs) are mounted on the roof of the train to provide seamless connectivity. The BSs, which are placed 210 m apart as the coverage area L cov for each BS is 210 m, transmit the received signal from the relays to the train [9]. The Tx 1 is connected to an AR connected to the backbone fibre network.…”