With the proliferation of mobile devices in recent years, the volume of global mobile data traffic has grown exponentially. As a result, effective approaches for mobile data offloading are urgently required. In the past few years, two main Wi-Fi offloading techniques, namely, opportunistic offloading and delayed offloading, have been widely discussed. A promising L4-approach known as multipath transmission control protocol has recently been standardized, which allows a single transport connection to use multiple paths simultaneously over multiple interfaces, which then calls for a new Wi-Fi offloading model that considers discontinuous Wi-Fi connection periods. This paper presents an analytical model for multipath Wi-Fi offloading in deriving the aggregate offloading time via an alternative path for the use of multipath offloading. Then, the respective offloading volume and ratio are computed. Our theoretical results are supported by extensive simulations. We show how this model further assists the cellular operators to make better decision in resource allocation. Compared with opportunistic offloading, multipath offloading results in a significantly improved performance in the support for a guaranteed minimum bit rate.

In Long-Term Evolution (LTE), the security threat posed by malicious users can be reduced by using the traffic detection function (TDF) in the policy and charging control (PCC) system to inspect the packets passing through the Packet Data Network Gateway. However, as the volume of global cellular data traffic continues to grow, it becomes impossible for the TDF to inspect all of the packets. Consequently, more efficient Intrusion Detection Systems (IDSs) are required. Accordingly, the present study proposes a random packet inspection scheme in which the inspection rate is dynamically adjusted based on the perceived intrusion period of the session. An analytical model is proposed to evaluate the effect of the inspection rate on the intrusion detection rate, inspection cost, and detection latency. The validity of the proposed model is demonstrated through numerical simulations. It is shown that the model provides an effective means of setting the inspection rate in such a way as to maximize the intrusion detection rate, while simultaneously achieving a satisfactory tradeoff between the inspection cost and the detection latency.

Non-orthogonal multiple access (NOMA)-based diamond relaying (NDR) is an efficient approach for combining NOMA and relaying techniques in such a way as to enhance the achievable rate from the source to the destination in the network. This paper examines the problem of joint power allocation among all the transmission phases during the operation of such networks. Based on the Karush-Kuhn-Tucker (KKT) condition and the second-order sufficient condition (SOSC), at least the local optimal solution is derived and analyzed. In addition, a new protocol for NDR networks based on cooperative communications is introduced and the associated joint power-allocation problem is examined. It is shown that this cooperative NDR (C-NDR) network further improves the achievable rate in some typical placements of the relays. Simulation results verify the correctness of the deviation and confirm the effectiveness of the proposed joint power-allocation method for both NDR and C-NDR networks.