Study On Spectral Efficiency And Resource Allocation In Massive MIMO Uplink Systems

Recently,Massive Multiple-Input Multiple-Output(MIMO)have attracted a lot of attention because of it can excavate space resources deeply and improve the system spectrum efficiency and energy efficiency.Previous studies are based on Rayleigh fad-ing channel model,but Rice fading channel is more widely applied in practice.However,uplink transmission rate and energy consumption will have different changing trends in Rice fading channel because of the existence of line-of-sight transmission component.The performance of Massive MIMO is largely determined by the accuracy of the chan-nel status information(CSI),so the base station usually uses the pilot signal in uplink to estimate CSI of the uplink and downlink.Equal power allocation policy causes that the spectral efficiency decreases dramatically in the low SNRs.Based on the above back-ground,this thesis will study the spectrum efficiency and resource allocation of mul-ti-user MIMO uplink systems over Rayleigh and Rice fading channels respectively.Firstly,the thesis studys the massive MIMO uplink system spectrum efficiency.At MRC or ZF reciever,the thesis analyzes the expression of uplink spectrum efficiency over Rayleigh channel model,and derives approximate expression of uplink in Massive MIMO system over Rice fading channels.Moreover general power scaling laws are discussed in above channel models.The theoretical and simulational results show that the spectrum efficiency of uplink is convergent to a non-zero value in Rayleigh fading channel,when the sum of power scaling factor of data signal and pilot signal is one.In Rice fading channel,the transmission rate performance is not reduced while the trans-mission power of each user's data signal can be reduced to 1/M where M is the number of base station antennas.At last,the pilot design problem and power resource allocation problem in Massive MIMO system are studied from the perspective of uplink resources.The uplink resource allocation mechanism is introduced into Rice fading channel.In the case of fixed total emission power,the spectrum efficiency can be maximized with jointly optimization pilot signal length,the power of pilot signal and data signal.The simulation results show that the uplink resource allocation can improve system performance in Rayleigh channel.The pilot signal needs more power resource with low transmitted power,and the data signal power resources needed to increase gradually with the increase of trans-mission power.In Rice fading channel,the optimal length of the pilot signal is proved to be equal to the number of users in the cell,and the power resource allocation is affected by the Rice factor.It is more efficient to optimize that allocation of uplink resource when the Rice factor is small.The lower Rice factor,the more transmit power resources are required by pilot signal.With the increase of Rice factor,the gain of uplink resource allocation gradually decreases,and more transmitting power is used to transmit data signals.