This work, for the first time, tackles channel estimation design with pilots in the context of covert wireless communication. We consider Rayleigh fading for the communication channel from a transmitter to a receiver, both additive white Gaussian noise (AWGN) and Rayleigh fading for the detection channel from the transmitter to a warden. Before transmitting information signals, the transmitter has to send pilots to enable channel estimation at the receiver. For the case with AWGN detection channel, we first analytically prove that transmitting pilot and information signals with equal power minimizes the warden's detection performance. This motivates us to consider the equal transmit power and then optimize channel use allocation between pilot and information signals under this case. Our analysis shows that the optimal number of the channel uses allocated to pilots increases as the covertness constraint becomes tighter. For the case with Rayleigh fading detection channel, we present a general framework to optimally allocate transmit power and channel uses between pilot and information signals. Our examination shows that the covert communication performance gain achieved by this general framework is not remarkable relative to the scheme with equal transmit power and this gain diminishes as the covertness constraint becomes stricter.

Various application scenarios with multi-services are rising to prominence in Intelligent Transportation Systems (ITS). To better optimize ITS based-on Wideband Code Division Multiple Access (WCDMA) networks, the soft handover management is an indispensable technology. In this paper, a dual handover prioritization (DHP) scheme which is composed of two layers prioritization design is proposed to guarantee different Quality of Service (QoS) requirements of multi-services in ITS, where the first layer is operated by reserving dedicated channels and building handover buffer for handover calls to guarantee the QoS of handover calls from the macro-perspective. And the second layer is executed by scheduling the waiting handover calls according to its priority level which is proportional to its QoS requirement from the micro-perspective. Then, an analytical model is built to evaluate the performance of the proposed DHP scheme in ITS based-on WCDMA. Results show the superiority of the proposed DHP scheme compared with conventional soft handover schemes in ITS based-on WCDMA.

Machine-to-Machine (M2M) communication is rising to prominence in wireless networks. Besides the research hotspot on the random access (RA) overload solution, the energy consumption (EC) problem of massive synchronized machine type communications (MTC) devices should also be considered urgently. In this paper, a joint energy-saving mechanism is proposed for M2M communication, which composed of overload protection and resources allocation. The first phase is operated by clustering technology, which preliminary achieve a relatively minimum system EC. The second phase is executed by resources allocation to further minimize EC of M2M system. The analysis and simulation show that the joint control mechanism can perfectly minimize EC of M2M communication, which consistent with the concept of green communication. Furthermore, the introduction of overload protection scheme can greatly decrease RA blocking probability and largely minimize system signaling consumption, which consistent with the new proposed concepts of low-cost UE design in M2M system.