The introduction of mobile edge computing (MEC) in vehicular network has been a promising paradigm to improve vehicular services by offloading computation-intensive tasks to the MEC server. To avoid the overload phenomenon in MEC server, the vast idle resources of parked vehicles can be utilized to effectively relieve the computational burden on the server. Furthermore, unbalanced load allocation may cause larger latency and energy consumption. To solve the problem, the reported works preferred to allocate workload between MEC server and single parked vehicle. In this paper, a multiple parked vehicle-assisted edge computing (MPVEC) paradigm is first introduced. A joint load balancing and offloading optimization problem is formulated to minimize the system cost under delay constraint. In order to accomplish the offloading tasks, a multiple offloading node selection algorithm is proposed to select several appropriate PVs to collaborate with the MEC server in computing tasks. Furthermore, a workload allocation strategy based on dynamic game is presented to optimize the system performance with jointly considering the workload balance among computing nodes. Numerical results indicate that the offloading strategy in MPVEC scheme can significantly reduce the system cost and load balancing of the system can be achieved.

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The design method is proposed for the community health emergency ambulance system based on Zigbee. The frontend sensors monitor vital physiological data and diagnosis. When the patient needs help, rescue request is send to rescue centers through the wireless sensor network. And localization algorithm estimates the location information in order to rescue the patient at the first time. Experiment shows that the system is safe and effective, and communication network is reliable.

The Chirp Spread Spectrum(CSS) based wireless communication has been widely used in Wireless Sensor Network(WSN). These sensors generally have slow speed, and is becoming more demand for higher data rate. However, due to the low transmission rate of CSS, there are still many problems to be studied. A new modulation method based on the linear chirps is introduced in this paper. Unlike the BOK(Binary Orthogonal Keying) and DM(Direct Modulation) methods, this modulation technique is to implant Doppler frequency shift into the linear chirps. M-ary modulation is realized in a single pulse by this proposed modulation technique. Demodulation is accomplished by calculating the position of the compress pulse peak within the pulse duration, or by using different reference chirp signals in the matching filter.

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