Secrecy guaranteed optimal traffic offloading via dual-connectivity in small cell networks

We investigate mobile user's (MU's) uplink traffic offloading based on the new paradigm of small-cell dual-connectivity (DC) that allows a MU to simultaneously offload traffic to a small-cell base station (sBS) and send data to a macro base station (mBS). In spite of the benefit of reducing the MU's power consumption, traffic offloading via DC leads to a security issue, i.e., a malicious node close to the sBS might intentionally eavesdrop the MU's offloaded data by receiving the MU's radio signal. Therefore, we formulate an optimization problem that jointly determines the MU's traffic scheduling and transmit-powers to the sBS and mBS, with the objective of minimizing the MU's total power consumption, while guaranteeing both the MU's secrecy requirement and traffic demand requirement. To solve the formulated joint optimization problem, we propose an effective layered-algorithm (which exploits the hidden convexity of the problem) to solve it and compute the MU's optimal offloading solution. Numerical results validate the efficiency of our algorithm and the significant influences of the MU's secrecy requirement.