# The Role of Smart Meters in Enabling Real-Time Energy Services for Households: The Italian Case
## 6 Communications Technologies for Real-Time Home Services
### Wireless Technologies
One additional benefit of IoT Dedicated Networks is the traffic offload from the legacy mobile cellular networks. However, they typically support low-rate streams (especially in the downlink channel) due to the need for reduced power consumption and to the narrow transmission bandwidths. * _wM-Bus_[55] is the reference ETSI standard EN13757-4 for gas smart metering over the 169-MHz band, but can also be applied to water and electricity meters, possibly enabling multi-utility \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Characteristics** & **NB-IoT** & **LTE-M** & **EC-GSM** \\ \hline Frequency (MHz) & 700-800 & LTE Band & 800–900 \\ Bandwidth (MHz) & 0.005 (UL); 0.00375 (DL) & 1.4 & 0.2 \\ DataRate Upload & 48 kbps & 20 kbps & 100 kbps \\ DataRate Download & 200 kbps & \textless{1 Mbps} & 100 kbps \\ Duplex & half & half & half \\ Interference tolerance & good, licensed spectrum & good, licensed spectrum & good, licensed spectrum \\ Coverage range & 2–15 km & \textless{11 km} & \textless{15 km} \\ Specs/Standard & 3 GPP R 13 & 3 GPP R 12/13 & 3 GPP R 13 \\ Transmission power & 23 dBm & - & 23–33 dBm \\ Licensed/unlicensed band & Licensed & Licensed & Licensed \\ Standard \& commercial products & Available & 2016 & 2016 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of LTE-M, NB-IoT, and EC-GSM technologies. mtering services. It supports only star-network topologies and requires the installation of dedicated concentrators. * _LoRaWAN_[56] is a protocol stack defined by the LoRa Alliance for low-power, wide area IoT communications technologies supporting deep-indoor transmission. It can be operated over different spectrum portions according to local regulations and supports a two-tier star-like topology, with gateways collecting data from field devices and forwarding them to dedicated NetServers associated to a cloud platform. The medium access control layer specifies three different classes with different downlink capacities. Authentication and encryption capabilities are also supported. * _SIGFOX_[57] exploits ultra-narrowband transmitters incorporated in the field devices. Like LoRaWAN, it supports a two-tier topology where SIGFOX gateways convey the traffic to cloud servers. The communications is mostly uplink, but it is possible to activate a tiny downlink control channel. Messages of at most 12 bytes are repeated multiple times over different frequency channels to increase the transmission robustness. A maximum of 140 messages per day is allowed for transmission. A comparison of the three above presented technologies is reported in Table 5.  
_Multi-Tier Networks_ leverage gateway nodes that concentrate the traffic generated by field devices through short-/medium-range wireless technologies and convey it to the backhand via a long-range backhaul infrastructure. They are specifically tailored for applications involving limited numbers of field devices and requiring low communications ranges. To compensate for such short ranges, the field devices may be organized in a mesh network topology supporting multi-hop transmission. Among the major solutions for low-power wireless personal area networks, we focus _on Bluetooth Low Energy (BLE)_ and _Wi-Fi HaLow_ (802.11 ah). * _BLE_[58] aims at reducing the power consumption of the legacy Bluetooth for application to long-lasting battery-powered devices. Its protocol stack is designed for easy integration with IPv6, and supports packet segmentation and cryptographic capabilities. Presently, it supports only star topologies, though an extension to a mesh scenario is currently under study. * _Wi-Fi HaLow_[59; 60] extends the coverage range of previous Wireless Fidelity (Wi-Fi) solutions while maximizing the number of connected devices (up to 8000). It supports power-saving operating modes that deactivate the radio module during idle periods and includes optimization mechanisms to effectively alternate short data transmission periods and long sleeping periods.