## 3 QoS Self-Provisioning and Interference Management Concept
### Step 2--Uplink Parameter Verification  
Next, it is assumed that a single virtual MUE representing all uplink traffic generated towards the overlaying macrocell is located just outside the femtocell coverage. Such a case corresponds to the situation where the HNB is exposed to the highest possible uplink interference from overlaying MUEs, hence it is the worst-case scenario. This step is necessary to properly evaluate the dependencies between pilot channel configuration and uplink QoS agreed between end-user and an operator. Secondly, it is assumed that the femtocell boundary is a single apartment or house. The path loss from MNB to HNB can be computed from the known macro CPICH power and the measured macro RSCP at the HNB. Therefore, in order to estimate the path loss from MNB to MUE, and according to the assumptions the virtual MUE is located at femto cell edge and outside the building, the path loss from MNB to MUE, \(PL_{\textit{MUE}-\textit{MNB}}\), is described as  
\[PL_{\textit{MUE}-\textit{MNB}}=\frac{P_{CPICH\_macro}}{RSCP_{CPICH}^{macro}} \cdot\frac{1}{PL_{femto}\cdot L_{p}}=\frac{P_{CPICH\_macro}}{P_{CPICH}^{opt} \cdot L_{p}} \tag{2}\]  
where \(L_{p}\) is the external wall penetration loss and \(P_{CPICP\_macro}\) is the common pilot channel transmit power of the surrounding macro. The external wall penetration loss is included here since we assume that the desired femtocell coverage area is confined to the indoor space. If the femtocells are installed outdoor with a certain desired coverage area, the value of \(L_{p}\) should be set to 0 dB. This virtual MUE is having a transmission power in the way that it contributes to the full macro-layer noise rise within its own macrocell. The total power from this virtual MUE received at the nearest macro is thus calculated taking into account the allowed NR and the NR consumed from ohtercell interference, which is not mapped into the virtual MUE. The received power at the nearest macro from the virtual MUE can thus be estimated as \[P_{MNB-MUE}^{RX}=P_{Noise}\cdot\left(\frac{NR_{macro}-1}{1+iF}\right) \tag{3}\]  
where the constant \(P_{Noise}\) is the thermal noise power measured at the MNB which equals \(-102.7\) dBm. The parameter \(iF\) represents the other macrocells interference to own macrocell interference ratio and is further described in [1]. Knowing the path loss from the virtual MUE to the MNB as well as an assumed fading margin, \(F_{Margin}\), needed to accommodate the expected fading observed by the MUE, we get to the final expression for virtual MUE transmit power as  
\[P_{MUE}^{TX}=P_{MNB-MUE}^{RX}\cdot PL_{MUE-MNB}\cdot F_{Margin}. \tag{4}\]  
The transmission power of the virtual MUE has a significant impact on the interference reception at the HNB and has an influence on the transmission power of the HUE in order to guarantee a certain femto uplink performance. Still assuming the virtual MUE being located just outside the femto house/apartment received power from the virtual MUE at the target HNB, \(P_{HNB-MUE}^{RX}\), is computed as  
\[P_{HNB-MUE}^{RX}=\frac{P_{MUE}^{TX}}{PL_{fmmo}\cdot L_{p}}. \tag{5}\]  
Not only does the virtual MUE cause interference at the HNB, also MUEs connected to other macrocells create interference to the HNB as the virtual MUE only represents the UL traffic for the overlaying macrocell. Therefore, the received power at the HNB from other MUEs is also calculated, \(P_{HNB-Iother}^{RX}\).