[9] “3GPP Technical Report 36.842. Small cell enhancements for E-UTRA and E-UTRANHigher Layer Aspects”, V1.0.0 (2013-11) www.3gpp.org [10] S. Jha, et.al., “Dual Connectivity in LTE Small Cell Networks,” in IEEE Globecom. , Dec. 2014. [11] Y. Wu, et.al., “Joint Scheduling and Power Allocations for Traffic Offloading via Dual-Connectivity,” in ArXiv. , Sep. 2015. [12] Y. Wu, et.al., “Traffic Scheduling and Power Allocations for Mobile Data Offloading via Dual-Connectivity,” in IEEE ICC , 2016. [13] Y. Wu and L. P. Qian, “Energy-Efficient NOMA-enabled Traffic Offloading via Dual-Connectivity in Small-Cell Networks,” in IEEE Commun. Lett. , 2017. [14] S. Singh, et.al.,“Proportional Fair Traffic Splitting and Aggregation in Heterogeneous Wireless Networks,” in IEEE Commun. Let. , May. 2016. [15] H. Wang, et.al., “Dual connectivity for LTE-advanced heterogeneous networks,” in Springer, Wireless Networks , May. 2016. [16] M. Kim, et.al., “Sum-Rate Maximizing Cell Association via Dual-Connectivity,” in International Conference on Computer, Information and Telecommunication Systems (CITS) , 2015. [17] P. Legg et. al., “Load balancing and aggregation algorithms for LTE dual connectivity”, in IEEE VTC , 2016. [18] S. A. Ahmad and D. Datla, “Distributed Power Allocations in Heterogeneous Networks With Dual Connectivity Using Backhaul State Information”, in IEEE Trans. Wireless Commun. , Aug. 2015. [19] M. A. Lema et. al., “Flexible Dual-Connectivity Spectrum Aggregation for Decoupled Uplink and Downlink Access in 5G Heterogeneous Systems,” in IEEE JSAC , Nov. 2016. [20] M. S. Pan et.al., “Downlink Traffic Scheduling for LTE-A Small Cell Networks With Dual Connectivity Enhancement”, in IEEE Commun. Lett. , Apr. 2016. [21] V. Singh, et.al.,“Optimizing user association and activation fractions in heterogeneous wireless networks,” in IEEE WiOpt , June. 2015. [22] Q. Ye, et.al., “User association for load balancing in heterogeneous cellular networks,” in IEEE Trans. on Wireless Comm. , June 2013. [23] J. Lee, et.al., “Non-monotone submodular maximization under matroid and knapsack constraints,” in STOC , 2009. [24] M. Minoux, “Accelerated greedy algorithms for maximizing submodular set functions,” in Optim. Tech., LNCS , 1978.