# The Role of Smart Meters in Enabling Real-Time Energy Services for Households: The Italian Case
## 7 Assessment of the Available Architectures
### Awareness Category  
This category comprises two use cases, namely A5 and A10, with strict latency requirements and sampling rates, both on the order of seconds, as well as several other use cases with loose latency requirements, ranging from 1 min to 1 h.  
Architecture 1 is suitable for the use cases in this category in case of PLC-C or dedicated cabling, while 6 loWPAN, BLE, or Wi-Fi HaLow can only be used if the SM is sufficiently close to the IHD (up to a few meters). With respect to use cases A5 and A10, which have stricter requirements, PLC-C can meet those requirements if the number of SMs communicating over the same power line is low enough. In fact, the limited available bandwidth, together with the usage of the CSMA protocol, may result in transmission delays or even lost messages.  
Most of the use cases can be implemented by installing a stand-alone device at the user premises, except for A3, A7, and A8, which require information from external sources such as retailers, DSOs, and the electricity market, and therefore need a connection to an external communications network.  
Architecture 2 leverages on the customer HAN, which generally has higher bandwidth, lower access delays, and also access to external sources of data through the public Internet, making this architecture suitable for all the services in the Awareness category. The main drawback of this architecture, which affects all the service categories, is that the SM may be out of reach of the customer HAN, or may not support its technology.  
Architecture 3 is also a viable choice, making it possible to provision the use cases in this category without installing additional devices at the user premises, but only requiring the customer's authorization to deliver data from the SM to a third party service provider. Technologies suitable for this kind of architecture can be cellular technologies like LTE-M, EC-GSM, NB-IoT, or even dedicated LPWAN solutions such as LoRa, SIGFOX, and wM-Bus. The former generally provide higher service availability, stemming from the usage of licensed bandwidth, but require the involvement of a third party. It is worth noting that these technologies provide low bit-rate channels, making use cases A5 and A10 unfeasible if there are many subscribers. Latencies are generally low enough for any use case, but may vary according to the number of active nodes. In this case cellular-based technologies generally cope better with higher traffic conditions. It is also worth noting that some LPWAN solutions do not support downlink transmissions well, making these technologies less useful or not adequate for the use cases requiring access to external data, such as A3 (cost estimation).  
The two-tier Architecture 4 uses the same technologies as Architecture 1, typically PLC-C, from the SM to an IHD-GW node and the same technologies as Architectures 2 and 3 from the IHD-GWto the end user. Architecture 4 makes it possible to receive data both from external sources and from SMs out of the HAN range, making it possible to satisfy the requirements of all the use cases in the Awareness category. With respect to the use cases with stricter latency requirements, the PLC-C segment or the LPWAN segment, if present, might become a bottleneck if there are many subscribers.