We consider distributed storage (DS) to reduce the communication cost of content delivery in wireless networks. Content is stored in some mobile devices using an erasure correcting code. Users retrieve content from other devices using device-to-device communication or from the base station (BS). We address the repair problem when a device that stores data leaves the cell. We introduce a repair scheduling where repair is performed periodically and derive analytical expressions for the overall communication cost of content download and data repair as a function of the repair interval. These expressions are then used to evaluate the communication cost entailed by DS using several erasure correcting codes. Our results show that DS can reduce the communication cost with respect to the case where content is downloaded only from the BS, provided that repairs are performed frequently enough. The required repair frequency depends on the code used for storage and network parameters. If devices storing content arrive to the cell, the communication cost using DS is further reduced and, for large enough arrival rate, it is always beneficial. We show that MDS codes, which do not perform well for classical DS, can yield a low overall communication cost in wireless DS.
Pedersen et al. recently studied the cost of content caching on mobile devices using erasure codes REF .
Distributed Storage in Mobile Wireless Networks with Device-to-Device Communication
IEEE Transactions on Communications
IEEE Transactions on Communications
Computer Science Mathematics