Review Article

Wireless Communications in Smart Rail Transportation Systems

Table 4

Example of different wireless communications systems customized for critical and noncritical communications.

ParameterCriticalNoncritical
GSM-RLTE-RLTEWLAN 802.11xxSatellite

FrequencyUplink: 876–880 MHz 
downlink: 921–925 MHz
450 MHz, 800 MHz, 
1.4–1.8 GHz
800 MHz, 1.8 GHz, 2.6 GHz2.4/5.7 GHz, 24/28/33 mmW12/14 GHz
Bandwidth0.2 MHz1.4–20 MHz1.4–20 (100) MHz80 (160) MHz10–16 MHz
Modulation/multiple accessGMSKQPSKM-QAMM-QAMQPSK
FDD + TDMFDD + OFDMFDD + OFDMTDD + OFDMFDD
Peak data rate, downlink/uplink172/172 Kbps50/10 Mbps100/50 Mbps433.3 Mbps10/1 Mbps
Peak spectral efficiency0.33 bps/Hz2.55 bps/Hz16.32 bps/Hz4.8 bps/Hz1 bps/Hz
Maximum transmission delay<50 ms<100 ms<1 s<1 s<1.5 s
Data transmissionRequires voice call connectionPacket switchingPacket switchingPacket switchingPacket switching
Packet retransmissionNo (serial data)UDP packets, 0 retransmissionsIP packets with up to 5 retransmissionsIP packets, up to 5 retransmissionsIP packets, 0 retransmissions
MIMOSISO, ,, up to 15no
(diversity)
MobilityMax. 500 km/hMax. 500 km/hMax. 350 km/hMax. 250 km/h>500 Km/h
Handover success rate≥99.5%≥99.9%≥99.5%≥99.5%
Handover procedureHardSoftHard/softHard/softNo handover
All IP (native)NoYesYesYesyes