# QoS-Guaranteed Radio Resource Management in LTE-A Co-Channel Networks with Dual Connectivity
## 2 System Model
### Guarantee Quality of Service (QoS)  
In order to evaluate the system performance such as throughput, most literature assume UEs have full buffer. However, in reality, each UE has its own traffic characteristic and quality of service requirement. Allocating resources more than a UE's needs does not increase system throughput. In this work, we considered two types of traffic, each with its own bandwidth requirement. By considering voice traffic and video traffic, we classified two types of the traffic into two QoS categories: Guaranteed bit rate (GBR) and maximum bit rate (MBR). The characteristics of each QoS requirement are described as follows [26]:  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Configuration** \\ \hline Simulation time & 500 TTI \\ Cellular layout & Wrap around, 7 Macros, 3 sectors per site \\ Carrier frequency & 2.14 GHz \\ Bandwidth & 10 MHz \\ Number of RBs & 50 \\ Number of UEs per sector & 5 \\ Macro transmit power & 46 dBm \\ Thermal noise & \(-\)174 dBm/Hz \\ Pathloss model & As in 3 GPP TS 36.942 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Simulation parameter of the optimal resource allocation.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Similarity** & **Degradation of Obj. Func. (1)** & **Degradation of Obj. Func. (2)** \\ \hline Max method & 93.96\% & 0.43\% & 0.67\% \\ Random method & 36.03\% & 37.99\% & 48.42\% \\ Max-Min method & 87.62\% & 0.47\% & 0.83\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Experimental results.  
* **Guaranteed bit rate (GBR):** Some applications, such as audio, require a fixed amount of bandwidth continuously during their lifetime. Thus, the traffic characteristic as well as QoS requirement of this kind of traffic is a constant data rate.
* **Maximum bit rate (MBR):** Yet, other types of applications, such as video, require a variable amount of bandwidth. The traffic may be bursty, and is usually characterized by a peak data rate and a sustainable data rate. Thus, we set the QoS requirement of MBR with two parameters, namely a minimum of the sustainable data rate (or average data rate) and a peak (maximum) data rate.  
We took the QoS requirement into consideration while scheduling RBs. That is, when a base station allocates RBs to UEs under its coverage, it will try its best to guarantee the QoS of each UE under the constraint of limited RBs. Specifically, to provide QoS guarantee to UE \(u\), the number of RBs to be allocated depends on its QoS requirement and channel condition. For GBR traffic, the required data rate is its guaranteed data rate while for MBR traffic, it is its minimum data rate. The number of required RBs for UE \(u\) can be calculated by following equation [24]:  
\[NRB_{u}=\left[\frac{UE_{u,QoS}}{RB_{data\_rate}}\right] \tag{5}\]  
where \(UE_{u,QoS}\) is QoS requirement for UE \(u\), \(RB_{data\_rate}\) is data rate of a RB, and \(NRB_{u}\) is the minimum number of the required RBs to satisfy the QoS of UE \(u\). If the base station has abundant RBs, it will not allocate more RBs to UEs with GBR traffic, instead, it will allocate to UEs with MBR traffic, but only up to their peak data rate.