Research On Capacity Optimization Of Multicast System With Imperfect Channel State Information

In recent years, wireless communication has been developing rapidly. Both the rising of information volume and the rapid spreading of new media make it hard that traditional point-to-point transmission mode meet the increasing demand, point to multi-point multicast transmission business naturally gets the attention of scholars: on the one hand, based on the mobile data traffic statistics : video traffic accounts for more than half of the whole share, most of which have the characteristic that different users need receive the same data content, such as video on demand, mobile television, remote education, etc. on the other hand, space electromagnetic wave transmission makes wireless channel have the radio properties, users owing keys can receive information from the same content provider at the same time.In this article, we analyze the multicast system, based on that the transmitter can get imperfect channel state information, set up capacity optimization mathematical model under different scenarios, solving the corresponding optimization problem for transmit strategy, then simulation analysis. The main work is: First of all, analyze the scenario that receiver with single antenna, taking use of the feedback of the instantaneous channel state information, considering the imperfect of feedback and transmission power restriction, set up maximize the worst channel capacity optimization model, prove it as a convex optimization problem, solve effectively by the convex optimization theory; Second, to overcome the shortcoming that the capacity is limited by the worst user channel state, set up system sum capacity optimization model, at the expense of all users receiving reliable performance to improve system throughput. Then, analyzing system sum capacity maximization model, prove it can be converted to a convex optimization problem under the condition of low signal-to-noise ratio, efficiently solve by CVX; Finally, analyze scenario of receiver with multiple antennas, because of the increasing amount of system feedback and delay,instantaneous channel state information feedback is not cost-effective, in this case, we use the relevant statistics channel model, set up capacity optimization problem under the restriction of system power, taking advantage of the statistical channel state information we have known to simplify the optimization problem, a lower bound of system sum capacity is obtained by analyzing the expression, get the solution of optimization problem that maximize the lower bound with restrict conditions, then simulate results, compare strategic performance.