Queueing Theoretic Models for Uncoded and Coded Multicast Wireless Networks With Caches

Mahadesh Panju, Ramkumar Raghu, Vinod Sharma, Vaneet Aggarwal, Rajesh Ramachandran

Abstract: We consider a server connected to several users over a shared finite capacity link. Each user is equipped with a cache. File requests at the users are generated as independent Poisson processes according to a popularity profile from a fixed finite library of files. The server has access to all the files in the library. Users can store parts of the files or full files from the library in their local caches. The server should send missing parts of the files requested by the users. The server attempts to fulfill the pending requests with minimal transmissions exploiting multicasting and coding opportunities among the pending requests. We consider a queue in which requests for the same file from different users is merged and transmitted simultaneously to all the requested users. We study and compare the performance of this queuing system in terms of queuing delays when LRU caches are used and when coded caching schemes proposed in the literature are used. We provide approximate expressions for the mean queuing delay for these models and establish their effectiveness with simulations. We extend the analysis to the case when transmission errors are also taken into account.

External IDs:doi:10.1109/twc.2021.3103422