Joint Resource Optimization Of OSDM MU-MIMO Downlink Channel

Under a given modulation scheme and a target BER (bit error rate) requirement, itis difficult to increase the number of bits transmitted in each symbol (i.e., the rate),since this generally requires a significant increase of transmit power. In this paper, westudy how to increase the rate in multiuser multiple-input multiple-output (MU-MIMO)broadcast channels using only bit and power loading, without requiring additionaltransmit power.To solve this challenging problem, our approach is to carry out a joint design ofbit loading and power allocation over all streams, and meanwhile take user and streamselection into account. Specifically, we maximize the total number of bits per symbol(rather than the Shannon capacity) over all selected streams, under a target BERconstraint for each stream and a constant total transmit power constraint. To enableflexible user and stream selection as well as achieving a high total rate, we considerOSDM (orthogonal space division multiplexing) rather than BD (block diagonalization)based MU-MIMO broadcast channels. This article’s innovation work are as follows:Firstly we put forward a more practical optimization model in MU-MIMO in thispape. Under the condition of the total transmission power, the optimization goal is notshannon capacity, but the actual transfer rate of the system. And considering the qualityof each channel of communication requirement, we also take the BER constraints intoconsideration in the optimization model. Again considering the number of bits theactual system can achieve, the optimization model limite the highest the number of bitsper symbol can load on. Take MPAM and QAM modulation as an example, wededuced different BER expression with different modulation modes in MU-MIMOchannel. Based on the proposed optimization model we build a similar optimizationproblem.Secondly in order to solve this optimization problem, the user and data flow hasbeen selected and all has been choosed under the condition of parallel sub-channels. Inthis paper we puts forward an improved adaptive bit and power allocation algorithm, in which bit allocation and power allocation will be jointly optimized. Due to the numberof bits loaded in the modulation are all integers, the joint optimization scheme shouldbe integerize. In the optimization model, we take MPAM and QAM as an example.The simulation proves the advantages of the proposed joint optimization algorithm.Finally drew on low complexity users and mode selection joint optimizationalgorithm, and because of its optimization target is the shannon capacity, and does nottake the sub channel BER into consideration, but its computational complexity is low.In this paper, on the basis of this we propose a schme of the improved user selectionand data flow which is applicable to the optimization model. And to parallel theMU-MIMO sub-channels, we study the BD and OSDM algorithms. In order tomaximize the optimization goal we choose OSDM algorithm, and take user selectionalgorithm for joint OSDM algorithm optimization into account.Numerical results show that our proposed joint bit and power loading with OSDMuser and stream selection is effective in increasing the total transmission rate withoutconsuming additional resources. The presented optimization model and its solution canbe extended to other modulation methods except MPAM and QAM.