Research On Interface Between Link Simulation And System Simulation For Wireless Communication

System level simulation is usually used for evaluating performance of the whole wireless communication system. As a kind of simulation of multipoint to multipoint, it needs the support of link performance between every two points. However, measurement of link level performance in system level simulation is so costly, that we need introduce a so-called link to system interface method to separate link level simulation from system level simulation. Among numerous interface technologies, Exponential Effective SNR Mapping (EESM) method and Mutual Information Effective SNR Mapping (MIESM) method are most widely used. They both predict the link performance through mapping SNR of each subcarrier to an effective value. This paper mainly researched on these two algorithms.EESM is an approximate algorithm derived from symbol error rate of each subcarrier, providing us the ability to predict link performance with simple calculation. However, a precipitous decline occurs under the condition of high order modulation due to the lack of strict mathenmatical derivation. At first, this paper proposed a reference curve model to reduce the accidental error and applied it to simulation. Then for the purpose of improving algorithm performace of high order modulation, an enhanced method based on Logistic model was proposed. Through simulation result, it proved to be an effective method to improved prediction performance in the situation of high order modulation with simple computation.MIESM is a kind of L2S interface method based on information theory. It uses mutual information of every bit as the measurement of channel quality indicator. Consequently, it achieves the best performance among all existing L2S algorithm in terms of the whole curve. However, upper level simulation often focuses on a smaller area of the curve and errors from the other areas will have a negative influence on computing parameters. To solve this problem, this paper proposed a weighted parameter optimization method, aiming at improving predication accuracy in the key area. Via simulation, we validate the effect of this method.The existing link level simulation methods are almost completed with software.However, channels generated by software are too ideal to reflect all features of physical channel. Therefore, this paper proposed a combination of hardware and software design scheme of simulation platform, which uses software to process baseband sigmals and hardware to simulate channels. As it avoided designing electronic circuit, this schme could control the simulation cost, and it was more closed to real scene. To prove the feasibility of this scheme, a systematic test is completed.