## 4 Simulation Results
The latter is naturally a result  
Figure 6: Displayed key performance metrics for the three considered HNB Tx power setting methods in the dense urban scenario: **(a)** Probability that a UE with matching CSG identity inside the same apartments as its own HeNB experience a downlink throughput lower than 256 kbps; **(b)** average HNB transmit power. interference from nearby CSG HNB(s), causing macro-layer coverage holes, or dead-zones as it is also sometimes called. The best MUE performance is clearly observed for QoS-SP-IM algorithm. Here it is also visible that the cost of increasing the minimum target throughput inside their home with an accessible HNB comes at a cost of lower throughput for MUEs. As discussed earlier, a key benefit of our proposed algorithm is the dynamic adaptation of the CPICH and the HS-DSCH powers to reach optimal tradeoff among coverage and capacity. Figure 9 illustrates the potential of our proposed algorithm in the suburban case when compared to NOPC. In the method here, the target coverage of the algorithm is set to infinite which automatically instructs the algorithm to maximize the cell coverage to the point where target QoS in both downlink and uplink can still be maintained and ensuring that NR conditions are still met (see e.g., Table 2). Compared to the NOPC algorithm, we now also accept the use of maximum transmit power in the femtocell but we redistribute it optimally to the control and data channels to get the right balance. The result is clear: A net  
Figure 8: Dense urban downlink performance of macro users _versus_ algorithm for setting transmission powers (CSG case). Figure 7: Cumulative distribution function of HNB CPICH to total Tx power for the dense urban scenario. coverage gain of 10-15 meters is obtained in most cases. This is a clearly perceived advantage for remote buildings where femtocells are deployed mainly for coverage and safety (e.g., for emergency calls). As stated earlier, the joint optimization of downlink and uplink is important in order to scale the capacity and coverage of the cell (downlink parameters) while ensuring that the allowed budget for NR contribution as well as uplink performance of the femtocell is critically met. To simulate the different approaches, we deploy a large set of uplink users and they attempt to get a 3.8 Mbps uplink service (to test high noise rise risks). If a user gets reliable connection but less SINR, it is allocated the possible maximum uplink data rate. The NR statistics at the MNB is compiled and results are shown in Table 3.  
It is seen that without any uplink protection, the macro network is severely impacted by the presence of the HUE population. Across all simulations and cell locations, a NR of nearly 24 dB was experienced by a single HUE at the nearby MNB. Numbers are smaller on average but still significantly high to pose a threat to the macro-layer. With a fixed power capping of \(-20\) dBm, the noise rise contribution is effectively controlled, _i.e._, contributions in the 0.01 dB range. It is seen that the dynamic method of our solution, although it provides higher HUE transmit powers and performance when conditions are right, still effectively controls the NR contribution from the HNBs. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Uplink Interference Metrics**} & **No power control,** & **No power control,** & **QoS-SP-IM** \\  & **HUE allowed to** & **HUE power capping** & **(256 kbps), Adaptive** \\  & **transmit up to 24 dBm** & **of \(-20\) dBm** & **uplink power capping** \\ \hline Noise rise from worst-case HUE, & 23.95 dB & 0.21 dB & 0.14 dB \\ found across all simulated cells & 23.95 dB & 0.21 dB & 0.02 dB \\ \hline Mean noise rise from worst-case & 8.48 dB & 0.02 dB & 0.02 dB \\ HUE found in each simulated cell & 4.82 dB & 0.01 dB & 0.01 dB \\ \hline Mean per HNB NR contribution & 4.82 dB & 0.01 dB & 0.01 dB \\ across all HUE in all cells & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Uplink simulation results in a dense urban scenario.