Neighbors’ interference situation-aware power control scheme for dense 5G mobile communication system

Abstract

The next generation mobile communication (5G) systems is targeting very high data rate by deploying more number of small cells, but this deployment results in high cross-tier interference because of using the same frequency band. To solve this challenge, an efficient power control scheme is desired specially for the case of uplink scenario. Thus, to solve this challenge, we propose the neighbors’ interference situation-aware uplink power control (IA-ULPC) scheme to reduce the cross-tier interference. In this scheme, we consider the interference situation of the neighbor cells while controlling the power of the users. Moreover, we also derive the target signal-to-interference and noise-ratio ($P_0$) equation to dynamically adjust it based on the neighbors’ base station interference situation. We compare the performance of the proposed IA-ULPC with the conventional fractional power control scheme (C-FPC). The extensive system-level simulations are carried out to prove the validity of the proposed IA-ULPC scheme which almost doubles the user average throughput and also decreases the interference around 20% in dense two-tier heterogeneous network environment as compared to C-FPC.

Appendix

The transmit power of the FUE/MUE in the serving FeNB/eNB is derived as follows:

$$\begin{aligned} P_{\textit{PUSCH}}^{\textit{serv}}=\textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}+PL^{\textit{serv}}+\overline{\textit{IOT}}^{\textit{interf2serv}} \end{aligned}$$

(13)

By utilizing (4) in (13), we can describe it as:

$$\begin{aligned}&P_0^{\textit{serv}}+\alpha PL^{\textit{serv}}=\textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}\nonumber \\&\quad +\,PL^{\textit{serv}}+\overline{\textit{IOT}}^{\textit{interf2serv}}\nonumber \\&P_0^{\textit{serv}}=\textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}+(1-\alpha )PL^{\textit{serv}}\nonumber \\&\quad +\,\overline{\textit{IOT}}^{\textit{interf2serv}} \end{aligned}$$

(14)

By substituting (9) in to (14), we can write as:

$$\begin{aligned} P_0^{\textit{serv}}= & {} \textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}+(1-\alpha )PL^{\textit{serv}}\nonumber \\&\quad +\,10\log _{10}\left( \sum \nolimits _{n=1}^{N}P_{n\_0}^{\textit{lin}\_{\textit{interf}}}\times \delta _n\right) -N_{\textit{therm}} \end{aligned}$$

(15)

Suppose $P_{n\_0}^{\textit{lin}\_{\textit{interf}}}$ is same for all the neighbor cells, then we have

$$\begin{aligned} P_0^{\textit{serv}}= & {} \textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}+(1-\alpha )PL^{\textit{serv}}\nonumber \\&\quad +\,10\log _{10}\left( \underbrace{P_{n\_0}^{\textit{lin}\_{\textit{interf}}}}_{\text {A}}\times \underbrace{\sum \nolimits _{n=1}^{N}\delta _n}_{\text {B}}\right) -N_{\textit{therm}} \end{aligned}$$

(16)

By applying log product rule, that is, $\log (A \times B)=\log (A)+\log (B)$. Thus we have:

$$\begin{aligned} P_0^{\textit{serv}}= & {} \textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}+(1-\alpha )PL^{\textit{serv}}\nonumber \\&\quad +\,10\log _{10}\left( P_{n\_0}^{\textit{lin}\_{\textit{interf}}}\right) +\,10\log _{10}\left( \sum \nolimits _{n=1}^{N}\delta _n\right) -N_{\textit{therm}}\nonumber \\ \end{aligned}$$

(17)

Since, $P_{n\_0}^{\textit{interf}}=10\log _{10}(P_{n\_0}^{\textit{lin}\_\textit{interf}})$. Thus, we can write (17) as:

$$\begin{aligned} P_0^{\textit{serv}}= & {} \textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}+(1-\alpha )PL^{\textit{serv}}\nonumber \\&+\,P_{n\_0}^{\textit{interf}}+10\log _{10}\left( \sum \nolimits _{n=1}^{N}\delta _n\right) -N_{\textit{therm}}. \end{aligned}$$

(18)

Thus, by rearranging (18) the total interference can be calculated as:

$$\begin{aligned} P_{n\_0}^{\textit{interf}}= & {} P_0^{\textit{serv}}-\textit{SINR}_{\textit{min}\_\textit{target}}^{\textit{serv}}\nonumber \\&\quad +\,(\alpha -1)PL^{\textit{serv}}-10\log _{10}\left( \sum _{n=1}^{N}\delta _n\right) +N_{\textit{therm}}.\nonumber \\ \end{aligned}$$

(19)