# Towards the Internet of Smart Trains:
## 4 Long Term Evolution (LTE): One Step Ahead of Broadband Communication Systems
### Current Status of Standardization  
The UIC General Assembly of 2008 proclaimed that the rise of the LTE communication system was threatening the life-cycle of GSM technology and affecting the maintenance of the equipment. As a consequence, the UIC presented a technical report with the results after examining \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **GSM-R** & **LTE-R** \\ \hline All-IP in native mode & No & Yes \\ Frequency & DL: 921–925 MHz, UL: 876–880 MHz & 450 MHz, 800 MHz, 1.4 GHz and 1.8 GHz \\ Bandwidth & 0.2 MHz & 1.4–20 MHz \\ Modulation & GMSK & QPSK and 16-QAM \\ Peak data rate & DL/UL: 172 Kbps & DL: 50 Mbps, UL: 10 Mbps \\ Peak spectral efficiency & 0.33 bps/Hz & 2.55 bps/Hz \\ Cell range & 8 Km & 4–12 Km \\ Cell configuration & Single sector & Single sector \\ Data transmission & Requires voice call connection & Packet switching, UDP data \\ Packet retransmission & No (serial data) & Reduced (UDP packets) \\ MIMO & No & \(2\times 2\) \\ Mobility & 500 Km/h & 500 Km/h \\ Handover success rate & \(\geq\) 99.5\% & \(\geq\) 99.9\% \\ Handover type & Hard & Soft (no data loss) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: System characteristics of GSM-R and LTE-R.  
whether LTE communication system would be applicable to the integrated railway wireless network. The main outcomes were that LTE technology might be relatively suitable for the near-future railway communication network and meet various requirements of railway, but noted that additional research would be required. Consequently, UIC officially launched the Future Railway Mobile Telecommunication System (FRMTS) project in 2013, which was aimed at developing the next-generation of railway communication solutions. In particular, UIC further strengthened its cooperation with the 3 GPP standard body in order to reflect requirements of the next-generation network in LTE standards. Furthermore, the future of transportation will rely on intermodal networks combining the railway, the subway, and road transportation. For example, in this scenario train-to-ground communications systems will be based on Wi-Fi and LTE-A systems. In a EU context, with the aim of develop cross-border connections between neighboring countries, and foster innovation and competitiveness, the strategic long-term policy includes the completion of the single European Railway Area (SERA, Directive 2012/34/EU). The ERA (Regulation (EC) No 881/2004) was established to promote SERA and to help revitalize the sector while reinforcing its essential advantages in terms of safety. As from 2016, the ERA will unify the large number of national technical rules and develop an improved safety culture (common methods, targets and indicators) under the Directive (EU) 2016/798. After a three year transition period, the ERA will be empowered to issue single EU-wide certificates for rolling stock and railway undertakings. Future wireless systems for railways need to address many issues like cost, spectrum allocation, and interoperability. Depending on the point of view, current technology is very expensive and sometimes it is not interoperable. GSM-R is, in some cases, a possible exception in terms of interoperability. However, open standards like 3 GPP LTE imply heavy costs and a possible dependence on mobile operators, which is unlikely to be accepted by railway operators, apart from other disadvantages. Despite all these issues, one of the aims of several research groups in Asia and Europe, and projects all over the world (for example, the Roll2 Rail Project [55]) is to study feasible wireless communication technologies for both train-to-infrastructure, inter-train and inside-train communications. 3 GPP LTE introduced some functionality on its latest releases that targets the railway sector, like mobile relays, or Device-to-Device (D2D) communications. The maturity of LTE standards to address railway requirements is briefly summarized in Table 8. Moreover, it is also important to notice the ongoing work on Cognitive Radio (CR) [56].