## 1 Introduction
The Ericsson 2016 [2] report has illustrated this trend Figure 3. According to this report, there were 3.9 billion smartphone subscribers in 2016, of which 1700 million are 4G, 1800 million are 3G (UMTS/HSPA), 300 million are 2G (GSM/EDGE), and another one million subscribers use other cellular mobile networks. It is estimated that by the year 2022, 2700 million persons will be added to 4G subscribers and 540 million persons to 5G subscribers, while 3G, 2G, and other mobile network technologies will lose 65 million, 95 million, and 130 million subscribers, respectively. According to an analysis by the Ministry of Information and Communications Technology (ICT) of Iran [5], the total portfolio of domestic operators was 6250 billion dollars in the year 2015, 74.1% of which was voice and SMS, and only 4.6% was mobile data. With the development of mobile infrastructure and the availability of high-speed broadband, as well as the widespread diffusion of various OTT technologies such as Telegram, a penetration rate of 78%, and Instagram with a penetration rate of 54% by the end of spring 2017, it is forecast that of the 20,937,500,000 dollar revenues for domestic operators in 2020, only 35.1% would be voice and SMS, and 26.9% for mobile data. It reflects the fact that by 2022, the share of voice and SMS will be halved, and the data share will roughly get six times higher. The portfolio revenue change of Iranian operators is shown in Figure 4. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Item** & **1G** & **2G** & **3G** & **4G** \\ \hline
**Development** & & & & \\
**time** & & & & \\
**Commercialization** & & & & \\
**time** & & & & \\
**Technical features** & Analog voice & Digital voice & Live podcast speed up & IP-based, multimedia, long-distance \\
**International** & AMPS, TACS, NMT & GSM, TDMA, DAMPS, CDMA, PDC & WCDMA, CDMA2000, DETC, TDSCDMA & 3 GPP \\
**Speed** & 1.9 Kbps & 9.6–172 Kbps & 382 Kbps-2 Mbps & 86–326 Mbps \\
**Application** & Voice & Voice and data & Voice, data, video call & voice, data, video call, online game, HD TV \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Different generations of MTTs from 1G to 4G [7]. Since the introduction of LTE technology for the first time in Iran (i.e., September 2014), domestic mobile operators have been investing heavily in developing this technology. The increase in coverage of this network from 47.86% in November 2016 to 58.82% in June 2017 indicates an increase in the number of 4G transmitter/receiver base stations (BTS) across the country. However, in spite of the large investments of the three main domestic operators, namely MCI, Irancell, and Rightel, in the development of 4G LTE network, as well as the increasing penetration of mobile broadband in the country--about 42.5% by the end of the spring of 2017--the LTE mobile penetration rate in Iran is estimated to be 10% by the end of spring 2017. This indicates that the main volume of mobile broadband subscribers in the country is still using UMTS/HSPA 3G networks. In other words, about 26 million of total mobile broadband subscribers (i.e., 34 million subscribers by the end of spring 2017) are currently using 3G cellular networks. Given the mobile broadband penetration rate and the third-generation share in it (85%), it is clear that mobile broadband subscribers are locked in these  
Figure 4: Evolution of revenue portfolio of Iranian Operators from 2015–2020 [5]. Figure 3: Number of smartphone users according to the type of cellular technology [2]. third-generation UMTS/HSPA networks, and the poor reception of the fourth generation will slow down future investments in LTE networks. This can result in some unintended negative consequences as following:  
* _Failure to provide a large number of high-quality services:_ With the help of LTE technology, operators can provide much more diverse and high-quality services.