## 4 The Architecture of IoT-Enabled Smart City
### Networking and Communication
#### 4.3.1 Evolutions of GSM and LTE  
The cellular network working groups handle the functions of administration of GSM/GPRS and Edge Radio Access Networks (GERAN). Their efforts are focused on introducing alternative methods to enhance the efficiency of GSM/GPRS for M2M communication. Various methods are available to improve M2M (machine-to-machine) communication efficiency. These approaches comprise upgrading the uplink capacity, extending the coverage for control and data channels, and reducing the power consumption and complexity of M2M devices [79]. Extended Coverage GSM (EC-GSM) is another progressive technique that utilizes Frequency Division Multiple Access (FDMA) in conjunction with Code Division Multiple Access (CDMA) on the uplink to accommodate a more significant number of IoT devices transmitting on the same frequency band. Bind repetition is achieved for all transport channels and extended the coverage regions. It is a technique where the transmitter repeats the same data block several times to achieve higher receiving gains. Different devices are used for different repetition levels in the blind repetition technique. Another approach is to support the narrowband GSM spectrum with channelization of 200 kHz. Narrowband Cellular IoT (NB-IoT) accommodates narrow asymmetric bands in downlink and uplink, where 200 kHz is divided into 48 narrowband channels are downlinkchannels, and 36 narrowband channels are divided into uplink channels. The Orthogonal Frequency Domain Multiple Access (OFDMA) is employed for the downlink, while the uplink uses Frequency Division Multiple Access (FDMA) to comply with the specific requirements of each device.  
One of the evolutions of LTE is LTE Rel-11 [80], which has focused on improving the overload functionalities of RAN for handling the access of many IoT devices with reduced capabilities. The complexity and the cost are reduced by reducing the radio transceiver and limiting the transport block sizes by allowing half-duplex FDD during the operation mode. Moreover, device power saving was also introduced, a significant advantage for IoT applications. Another substantial evolution is the LTE Rel-13 [80] which is improved at the physical layer by including the characteristics of narrowband transmission and provides a better response for M2M requirements. EC-GSM enables the use of cost-effective and low-power hardware while simultaneously enhancing coverage areas. Additionally, Rel-12 has undergone further enhancements and now features an Enhanced Power Saving mode (EPS) and Extended Discontinuous Reception (DRX) functionality.  
[PERSON] et al. have reported a framework for various applications from the perception of different communication technologies in a smart city scenario [81]. LTE technology has concentrated on leveraging small-cell technology to augment bandwidth within this framework. Small cell technology allows for inexpensive and low-power intelligent devices for various applications. LTE service can be deployed over a larger geographical area and can fulfil all communication necessities, including interoperability, low power consumption, resilient communication, and multi-modal access, which can enhance the overall quality of user experience. Thus, LTE service can be utilized for many applications and may be a superior option for smart cities.