  Routing in opportunistic networks is a very important and challenging problem
because opportunistic network utilizes the contact opportunities of mobile
nodes to achieve data communication.Social-based routing uses behavior of human
beings which can form a community with the same interests to deliver the
message.In this paper,we analyze the drawbacks of the original friendship-based
algorithm, which defined social pressure metric to determine nodes'friendship
community, but the metric couldn't distinguish the distribution
characterization of the connection length which has an important impact on the
selection of links with better quality. Further, the existing friendship-based
routing doesn't consider the buffer management, which is vital for routing
design in opportunistic networks. We propose a New Friendship-based routing
with buffer management based on Copy Utility, named NFCU. NFCU algorithm, which
not only considers the contact periods in constructing social pressure metric
to solve the drawbacks of the original friendship-based routing scheme
efficiently, but also considers the buffer management, that can efficiently
determine which copy of the message should be deleted timely according to the
copy utility function. Our proposed strategy can reduce the network overhead
significantly, and increase the message delivery ratio. The extensive
simulation results demonstrate that NFCU performs better than the original
friendship-based routing. Moreover, we compare NFCU with other four
classicalrouting schemes in opportunistic networks in terms of message delivery
ratio, average delay, and comprehensive metric- message delivery
ratio*(1/average delay). The simulation results show that our scheme NFCU can
achieve better performance.
