In this paper, the issue of content placement in multiple Cloud Radio Access Networks (CRANs) is addressed. In a CRAN, the contents are placed into the facilities of remote radio heads (RRHs) and baseband unit (BBU) pools to improve the performance of the content transmission. We aim to approach the objective of minimizing the total cost of content transmission to the users of multiple CRANs by considering joint content placement and storage allocation of RRHs and BBU pools. The problem is formulated as mixed-integer linear programming (MILP), which will be solved by a proposed algorithm in utilizing the rounding technology. We prove that the proposed algorithm can obtain the feasible solution of the MILP and has a competitive approximation ratio to the MILP. Further, the simulation results also validate that its solution obtained is very close to the optimal one of the MILP.

本文解决了多个云无线电接入网（CRAN）中的内容放置问题。在CRAN中，将内容放入远程无线电头（RRH）和基带单元（BBU）池中，以提高内容传输的性能。我们的目标是通过考虑RRH和BBU池的联合内容放置和存储分配，来实现将向多个CRAN用户传输内容的总成本降至最低的目标。该问题被表述为混合整数线性规划（MILP），将通过使用舍入技术的拟议算法解决该问题。我们证明了所提出的算法能够获得MILP的可行解，并且对MILP具有竞争性的近似值。进一步，