  Caching of popular content on wireless nodes is recently proposed as a means
to reduce congestion in the backbone of cellular networks and to improve
Quality of Service. From a network point of view, the goal is to offload as
many users as possible from the backbone network to the wireless caches while
at the same time offering good service to cache-unrelated users. Aggressive
offloading can lead to an unbalanced user association. Some wireless nodes can
be overloaded by cache-related traffic while the resources of others remain
underused. Given a fixed content placement, this work proposes an efficient
distributed algorithm to control and balance the association of cache-related
traffic among cellular cache memories. The algorithm allows the network to
achieve the globally optimal solution and can be executed on base stations
using a limited amount of information exchange between them. It is based on a
novel algorithm we call Bucket-filling. The solution limits the cache-users per
node by balancing the total load among the nodes in a fair way. The improvement
compared to common user assignment policies is highlighted for single- as well
as for multi-tier random networks.
