Exploiting the unexploited of coded caching for wireless content distribution

Recent studies show that the coded caching technique can facilitate the wireless content distribution, i.e, push the contents into user terminal, by mitigating the wireless traffic volume during the peak-traffic time, where the contents are partially prefetched to the local cache of mobile devices during the off-peak time. The remaining contents are then jointly coded and delivered in multicast, when many content requests are initiated in the peak-traffic time. The requested contents can be recovered from the local-prefetched and multicast data with requesters experiencing less congestions. However, the benefit of the coded caching scheme is still under estimated, where the potential gain by appropriate caching distribution is under exploited. In this paper, we propose a theoretical model to minimize the average wireless traffic volume required in the coded caching, for which the optimized caching distribution is derived with the content popularity distribution taken into account. In order to improve the computational efficiency for determining the appropriate caching distribution, we transform the objective function from the average wireless traffic volume into the average size of un-prefetched contents. We theoretically show the order optimality of the results derived from our model. Numerical results show that the coded caching performance can be further improved with our caching distribution design.