# A Novel Power-Saving Transmission Scheme for Multiple-Component-Carrier Cellular Systems
## 5 Results and Discussion  
In this section, numerical examples are presented to compare the power consumption of the proposed scheme for transmitting data in a multi-CC BS system with that of a conventional scheme in order to quantify the amount of power that could be saved by using the proposed scheme. In the conventional scheme, important elements of the proposed scheme, namely, the SAC, TPE, and SAD components, are simply excluded; in other words, all the CCs are constantly activated, regardless of any fluctuations in the traffic load. For our experiments, the example of a medium-sized urban macro-cell in which the BS utilizes three CCs for data transmissions was considered. Of the three CCs, one was assumed to be in the 700 MHz frequency band, while the other two were assumed to be in the 2 GHz frequency band. Recall that the three CCs were indexed with \(i\), with \(i\) = 1, 2, and 3, respectively. In addition, the following parameters were also assumed: \(T_{i}\) = 5 MHz; \(b_{\text{sub}}\) = 180 kHz; \(p_{i}\) = 10 W; \(p_{\text{trans,max},i}\) = 10 W; and one OFDMA downlink frame spans 25 sub-channels. We further assumed that all the users of the cell had a uniform spatial distribution, while the movements of the users were assumed to occur at 3 km/h in random directions. Path loss was assumed as the channel propagation model, with the Hata and COST 231 models being adopted for one CC in the 700 MHz frequency band and the other two CCs in the 2 GHz frequency band, respectively [31; 32]. The Hata path loss, denoted as \(L_{\text{Hata}}\) (in dB), is expressed as:  
\[L_{\text{Hata}}=69.55+26.16\log_{10}f_{1}-13.82\log_{10}h_{\text{b}}-\varphi(h _{\text{d}})+(44.9-6.55\log_{10}h_{\text{b}})\log_{10}d \tag{14}\]  
Note that, in Equation (14), \(f_{1}\) is the carrier frequency for the Hata path loss model, which is herein set equal to 700 MHz, \(h_{\text{b}}\) is the effective BS antenna height (in m), \(h_{\text{d}}\) is the user-terminal antenna height (in m), \(\varphi(h_{\text{d}})\) is a correction factor for the user-terminal antenna height, which is given by:  
\[\varphi(h_{\text{d}})=3.2\log_{10}(11.75h_{\text{d}})^{2}-4.97 \tag{15}\]  
and \(d\) is the distance between the BS and the user-terminal (in km). In turn, the COST 231 path loss, denoted as \(L_{\text{COST231}}\) (in dB), is expressed as:  
\[L_{\text{COST231}}=46.3+33.9\log_{10}f_{2}-13.82\log_{10}h_{\text{b}}-\varphi( h_{\text{d}})+(44.9-6.55\log_{10}h_{\text{b}})\log_{10}d \tag{16}\]  
where \(f_{2}\) is the carrier frequency for the COST 231 path loss model, which is herein set equal to 2000 MHz. In compliance with the application-layer service trend of the 4G and future 5G networks, we looked at RT sessions consisting of YouTube activities and NRT sessions consisting of file transfer protocol, hypertext transfer protocol, and social network activities as a study case. Session times of RT users were set to have a mean of 3 min and an exponential distribution. For NRT users, 20% of the total file size was assumed to be contributed from file sizes with a truncated lognormal distribution and a mean of 2 MB, while the other 80% was assumed to be contributed from files with a fixed size of 100 kB each. For a given user, the inter-arrival time of user session requests, meaning the period of time between the end of a session and the generation of a new request, was assumed to have an exponential distribution and a mean of 1 s. For the sake of convenience, \(\Re^{(m)}\) refers to the set of type-\(m\) users in the given cell. For the NRT users, the minimum required data rate \(r_{\text{req},k},k\in\Re^{(1)}\) was set to 300 kbps, while for the RT users, the minimum required data rate \(r_{\text{req},k},k\in\Re^{(2)}\) was set to 500 kbps.