Research For The MIMO Detection System And Power Allocation Algorithm

As the core competitiveness of future mobile communication system in physical layer,the purpose of the MIMO technology is to make full use of random fading and multipath propagation in the space to improve the data transmission rate,the channel capacity and the reliability of data transmission.This technology is usually accompanied by high data throughput,but it also means the multiplication of data traffic and higher bit error rate of the data.Moreover,the flow interference from the multiple antenna structure will have an serious effect on system performance.So,in order to guarantee the detection performance at the receiver in the presence of channel fading and flow interference,it needs to combine the effective power allocation technology with MIMO detection algorithm.Then the communication quality and channel capacity can be improved significantly.In this paper,the signal detection and power allocation in MIMO system are studied.The main work of this paper contains following several aspects:1.Considering the mutual restriction of system detection performance and complexity,this paper discussed the MMSE detector which has low complexity and can inhibit the interference from antennas and noise for soft-output MIMO detection system with channel coding.We have obtained the bit log-likelihood ratio of the received signal for deterministic channel estimation model and random channel estimation model separately with the consideration of channel estimation error and flow interference.Moreover,this paper constructed the power allocation optimization problem by minimizing the bit error rate of MMSE receiver.The power allocation algorithm what we have proposed has solved the power allocation for data transmission and pilot transmission in soft-output MIMO detection system under the condition of fixed total power consumption.It effectively improved the resource utilization and detection performance.The simulation results show that comparing to the MMSE detector with no channel estimation error and considering the channel estimation error,the scheme what we proposed can significantly improve the BER performance of the system.It gets performance gain of the detection system.The reasons are that this paper not only considered the existence of channel estimation error and flow interference,but also usedthe optimal method to get the optimal power allocation.Therefore,the communication quality has been improved effectively.2? For the traditional wireless node equipment needs to replace the batteries,this paper adopts the simultaneous wireless information and power transfer(SWIPT),which is one of the new type of energy harvesting,to minimize the system outage probability and has designed the power allocation algorithm for PS scheme in MIMO relay system.The scheme what we have proposed is optimized through KKT conditions.It mainly solves the power allocation problem for data transmission and pilot transmission at the source,the ratio of received information for energy absorption in relay node,and the ratio of data transmission and pilot transmission power for the second transfer of the data in relay node.The simulation results show that the power allocation algorithm can get the maximized detection performance of the system under SWIPT scheme.