## 6 Deployment Guidelines for NB PLC System Deployment
### PLC Performance Assessment  
As it has already been discussed, PLC LV networks cannot be planned as some other telecommunications technologies, as the topology and electricity elements of the LV grid are not generally known, and their influence over PLC communication channels cannot be generally predicted. This situation, combined with the variability of the loads in the LV grid (heavily dependent on end-user consumption patterns, and always producing some kind of noise), make ex-ante planning efforts worthless for Smart Metering networks. The alternative for network quality assurance in PLC based Smart Metering systems over LV grids is post-deployment performance monitoring and analysis. This monitoring should preferably be performed while Smart Metering networks are running in normal operation; however, the limited bandwidth characteristic of CENELEC A band LV Smart Metering PLC systems [53; 148], even more constrained if low frequency band is avoided as it happens in modern systems such as G3 and PRIME, make it difficult to develop real time supervision systems in networks comprising thousands of end-points sharing bandwidths of tens of kbps. As a consequence, intensive performance monitoring of network behavior suggested in [100; 150] appears to be the soundest alternative. Performance monitoring is intended to characterize the performance of a NB PLC systems subnetworks in terms of availability and stability, the two main concepts that show how a Smart Metering network behaves. Availability is defined in [150] for devices as \"_the accumulated time (relative to total time) when a device is accessible in the subnetwork_\" and for complete subnetworks as \"_related to the statistical values of the subnetwork elements as a group_\". Stability is defined in [150] for devices as \"_the capability of a subnetwork element to remain in a non-disconnected state_\", and for complete subnetworks as \"_related to the ability to maintain a stable number of registered elements_\". These concepts are crystalized in different measurable parameters that are reproduced in Table 2, adapted from [150]. Once the stage for network monitoring process is over, and the data are elaborated with the existing grid information, both the SSs and the smart meters' behaviors can be studied. Grid data is fundamental to correlate communications network behavior with LV grid existing information, to serve the triple purpose of detecting the location of the problems, understanding the effect of grid configuration, and assisting grid operations. The detection of the location of the problems is based on the identification of the elements (smart meters) in a LV grid that could be underperforming, through a correlation of the measured results and the grid location of these elements, and those that could subsequently communicate through them using PLC repetition capabilities. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Group** & **Subgroup** & **Type** & **Parameter** \\ \hline \multirow{8}{*}{A.1 Topology stability} & \multirow{8}{*}{A.1.1} & \multirow{8}{*}{Graph} & Time evolution of registered nodes: number of nodes _vs._ time. \\ \cline{3-5}  & & & Number of changes in the network (increment or decrement in the number of registered nodes) \\  & & & per minute. \\ \cline{3-5}  & & & Statistical values (maximum, minimum, average and standard deviation) of the availability of communications nodes measured along time. \\ \cline{3-5}  & & & & Statistical values (maximum, minimum, average and standard deviation) of the availability of communications nodes measured along time. \\ \cline{3-5}  & & & & Statistical values (maximum, minimum, average and standard deviation) of successful meter readings in each cycle. \\ \cline{3-5}  & & & & Statistical values (maximum, minimum, average and standard deviation) of the duration of successful reading attempts in each cycle. \\ \cline{3-5}  & & & & Statistical values (maximum, minimum, average and standard deviation) of successful reading attempts in each cycle.