## 4 Methodology for the Performance Analysis of the Physical Layer Proposals
### PLC Performance Metrics Based on ETSI TS 103 909 v1.1.1  
The test metrics used for this PLC performance study are defined by ETSI TS 103 909 V1.1.1 [15]. The usage of these metrics is thoroughly described in [10]. These metrics are given in terms of the link budget and effective data rate.  
Effective packet layer data rate (DR\({}_{\text{PKT}}\)) [15] is the number of bits delivered to the data-link layer divided by a full formatted packet cycle time. It provides a measurement of the cost of the physical mechanisms in the data rate available to upper layers.  
The link budget is a measure of how much signal attenuation can be present between transmitter and receiver such that a specified level of successful message delivery is achieved. That level of successful message delivery is established as a frame error rate (FER) of 5% [15]. As described in [10], given a physical configuration of the transmitter and a specific noise pattern, the Virtual PLC Lab calculates through iterations the minimum reception power that matches the target FER, which compared with the nominal transmission power provides the link budget.  
ETSI TS 103 909 V1.1.1 [15] specifies link budget metrics for each of the disturbance types defined in the document and some composite ones:  
* _Tonal noise link budget:_ First, the 25 individual measured link budgets are calculated and identified as \(LB_{tonal,i}\) for \(i\) from 1 to 25, corresponding to switching frequencies of \(21+5\)\(i\) kHz. These individually calculated link budgets are averaged. To provide added statistical weight to the most challenged result, while also considering the average, the overall tonal noise link budget is specified to be the lowest of the 25 individually measured link budgets, averaged with the previously calculated average, giving equal weight to those two figures.
* _Periodic impulse noise link budget:_ Defined as the link budget measured in presence of the periodic impulse noise.
* _Random impulse noise link budget:_ Defined as the link budget measured in presence of the random impulse noise.
* _Intentional communicator link budget:_ Defined to be the smallest of the four individual intentional communicator link budget values.
* _Composite link budget (\(LB_{\text{PHY}}\)):_ Defined to be the average of the following measurement values: _Unimpaired link budget_ (obtained for a noiseless environment), _tonal noise link budget, periodic impulse noise link budget, random impulse noise link budget_, and _intentional communicator link budget_. The _ununimpaired link budget_ averaged for the _composite link budget_ is capped to 80 dB.  
These metrics have been extended following the same approach to the non-intentional emissions selected from DER:  
* _dernu link budget_ (where _nn_ is _04, 06 34 36, 50_ and _51_): Each of these link budgets is defined as the link budget measured in presence of one of the der noises that gives its name.
* _der average link budget_: Defined to be the average of the six individual link budget values of DER.  
The information given by these metrics is complemented with new metrics defined as part of the research process described in [10]:  
* _Signal to Noise Ratio (SNR) required for AWGN:_ The minimum SNR required in order to decode physical packets with FER lower than 5% in the presence of AWGN. Reference the metric for the analysis of the results.
* _Tonal in-band noise link budget:_ A new metric defined in [10] to avoid the bias effect caused by some of the tonal noises included in [15] that are out of the bands of the communication systems under test. It considers only the disturbances in the communication band.
* _Composite in-band link budget:_ In a similar way to the _tonal in-band noise link budget_, the aim is to avoid the bias effect of the high link budgets related to noises in frequencies outside the communication band.