Technology Research On Simultaneous Wireless Information And Power Transfer Systems

Energy constrained wireless networks, such as sensor networks, is a typical powered by battery, only having a limited service life. Although charging battery can extend within a certain range, usually this is costly and inconvenient, in certain scenarios, it is even impossible,(for example, embedded in the body of a patient or construction sensor). A more convenient and secure way is to use multiple nodes simultaneous wireless information and power transfer technology.This thesis studys the problems of wireless system synchronization signal and energy transmission through various scenarios, and the corresponding power allocation algorithm to get the balance between maximize capacity and maximize the energy received. The main contents of this thesis can be summarized as follows:1. Study on the single-user scenarios of integrated optimization about wireless signal and energy synchronous transmission. First of all, we consider under the transmit power constraints, the receiving energy optimization problems based on the channel capacity, due to the optimization problem is difficult to discuss, so we try to solve the relaxation of optimal solution; then, we discuss the optimization of the case of SISO, we divide the sender into two types, it is unknown or known channel state information. Respectively, the power allocation strategy, the transmission power allocation and the receiving power allocation optimization problem are established, and the optimal solution of the two optimization problems is obtained. Secondly, we consider under the transmission power constraint, the optimization problem of the rate based on energy is considered, the mathematical optimization model is established, and the solving algorithm is proposed based on the theoretical analysis. Finally, the boundary line of the capacity energy tradeoff region is verified by numerical results, and the total energy of the system increases linearly with the increasing of the transmission power.2. Study on multi-user scenarios of the integrated optimization about wireless signal and energy synchronous transmission. Firstly, we discuss multiuser MISO scene under the capacity and energy constraints, the optimization problem of the maximization of the sum of energy received by all energy receives is established, and we consider signal receiver can eliminate the energy signal interference and can not eliminate the interference, so we can get two non convex quadratic constrained quadratic programming problem, through semi fixed relaxation and uplink and downlink duality method, we can solve the optimization problem. Then, the multi user MIMO system is discussed, and the optimization problem is transformed into a convex problem of SDP, and a two point iterative search method is proposed to solve the optimization problem. Finally, the numerical results show that with the increase of transmission power, capacity--energy region will continue to extend; if there is more energy receivers in the system, the total energy will become greater; the same, if there is more signal receivers, then system capacity will also become larger.3. Study the optimization problem of the wireless signal and energy transmission synchronous under the security communication scenario. We consider the wiretaps that may be encountered in security communication, and the use of artificial noise in MISO security communication system can ensure secure communication, at the same time, the energy will transfer to the free receiver, a multi-objective optimization problem of power allocation is established. In this paper, a new power allocation algorithm based on SDP is proposed, and by using the semi definite programming relaxation we can solve it. In addition, we will further propose two sub optimal solutions, numerical results show that the dual use of artificial noise, but also show the excellent performance of the sub optimal solutions.