Reduction Of Ofdm Systems Papr Minimum Coverage Round

Peak-to-Average Power Ratio(PAPR) is one of the two major drawbacks of an Orthogonal Frequency Division Multiplexing(OFDM) system,which makes it a hot topic these years.This thesis conducts research on reducing the PAPR of an OFDM system utilizing its spare sub-carriers,as a result of low SNR or surplus after resource scheduling.By using tone-reservation(TR) method,we can largely reduce PAPR of the system,without consuming effective bandwidth,without transmitter-receiver symbol handshake,in-band distortion and out-of-band radiation,only with a little add on signal transmission power.But the original TR method has the problem of large computational complexity and low converge speed as well.The thesis will first convert the TR method into a Minimum Spanning Circle(MSC) problem and prove that it can be commonly solved by using sequential quadratic programming(SQP).Further,the problem can also be optimized by our Minimum Spanning Circle Method (MSCM).The creative work has less computational complexity and faster converge speed than the one through SQP.Our Simulation will show that MSCM method has similar PAPR reduction performance with SeLected Mapping(SLM),a most frequently discussed PAPR reduction method.The advantage of MSCM over SLM is that MSCM doesn't need to change the receiver side,and can be easily merged into any existing OFDM protocols or systems.MCSM also has its application in Multiple Input Multiple Output(MIMO) OFDM system,an extension of OFDM system in space dimension.In V-BLAST MIMO-OFDM system,data transmitted by different antennas are independent and irrelevant in time domain.We can use Extended MSCM (EMSCM) in different antennas' optimization.While in MIMO-OFDM system with Space Time Block Code(STBC),we will prove that when comes the second OFDM symbol,the optimized result of MSCM in the first OFDM system can be directly used after some simple calculation is used,and so are the rest OFDM symbols in one MIMO period.This characteristic largely reduces the computational complexity of MSCM in STBC MIMO-OFDM system.When there are many spare sub-carriers or we don't want to use all the spare sub-carriers to reduce the PAPR due to the constraints of hardware's computation ability,we propose criteria to always choose the most the effective spare sub-carriers to reduce the PAPR,called Best Tone Selected Extended MSCM(BTS-EMSCM).The algorithm with the criteria further reduces the computational complexity with a little performance degradation.The effectiveness of the criteria will be proved by our simulation.