# QoS-Guaranteed Radio Resource Management in LTE-A Co-Channel Networks with Dual Connectivity
## 1 Introduction
Many studies indicated that the RSRP is conducive to large base stations (e.g., Macro BS), but not obvious for small cells (e.g., pico BS). In [16], the cell range expansion (CRE) scheme is investigated, in which the coverage of pico BS is extended by adding additional reference signal such that more UEs could select the pico BS rather than Macro BS. However, increasing the CRE bias value alone does not improve the performance of the small cell, as the cell edge users are significantly affected by the intercell interference. In [17], the serving cell is selected according to the signal-to-interference plus noise ratio (SINR) which considers not only the transmission power of the base station, but also the interference between the base stations. Many other factors are also considered in cell selection in the literature, such as load balance, utility function of proportional fair, dynamic strategy, and data transfer rate [18; 19; 20; 21]. In this paper, based on the special features of DC, we consider load balancing and downlink data transfer rate in the cell selection. Specifically, we first estimate CQI based on SINR and then estimate the number of resource blocks that a UE can be assigned, and finally calculate the actual data transfer rate. In the study of the enhanced intercell interference coordination, some previous works took the Almost Blank Subframe (ABS) into consideration [22; 23], in which a ratio of time slots of a frame of the Macro BS were preserved for the pico BS to achieve time domain coordination. Most of previous works adopted static ABS setting and showed that the ratio of 0.5 yielded the best performance. However, it may waste a lot of wireless resources of the Macro BS. In this paper, we proposed a better method to adjust the ABS ratio dynamically according to the network conditions. It would decrease the ABS ratio when the Macro BS is overloaded, and increase the ABS ratio to improve the throughput of pico BS when the load of Macro BS is low. Simulation results are given to substantiate theoretical findings with a comparison with fixed ABS configuration. Besides, there are various types of small cell and UEs with different bandwidth requirements in HetNet. Most literature focused on single traffic, which is not able to reflect the real-world situation [24]. Thus, in this work, multiple types of applications with different QoS requirements were considered. By considering voice traffic and video traffic, we classify two types of the traffic into different QoS indicators: Guaranteed bit rate (GBR) and maximum bit rate (MBR). The QoS requirement of GBR is a guaranteed fix transmission rate, while that of MBR is a guaranteed of minimum rate and a limit of maximum rate. The numerical results show that our proposed schemes had significant improvement in the QoS satisfaction ratio than previous works in the literature. The rest of this paper is organized as follows. Section 2 introduced system design. The proposed Max-min Threshold Scheduler (MTS), HetNet Congestion Indicator (HCI), and Q-learning dynamic ABS will be described in detail in Section 3. The system deployment and the simulation results present in Section 4. Finally, in Section 5, conclusion and future works are discussed.