Mobility-Aware Caching in D2D Networks

Rui Wang, Jun Zhang, S. H. Song, Khaled B. Letaief

Research output: Journal article publicationJournal articleAcademic researchpeer-review

111 Citations (Scopus)


Caching at mobile devices can facilitate device-to-device (D2D) communications, which may significantly improve spectrum efficiency and alleviate the heavy burden on backhaul links. However, most previous works ignored user mobility, thus having limited practical applications. In this paper, we take advantage of the user mobility pattern by the inter-contact times between different users, and propose a mobility-aware caching placement strategy to maximize the data offloading ratio, which is defined as the percentage of the requested data that can be delivered via D2D links rather than through base stations. Given the NP-hard caching placement problem, we first propose an optimal dynamic programming algorithm to obtain a performance benchmark with much lower complexity than exhaustive search. We then prove that the problem falls in the category of monotone submodular maximization over a matroid constraint, and propose a time-efficient greedy algorithm, which achieves an approximation ratio as 12. Simulation results with real-life data sets will validate the effectiveness of our proposed mobility-aware caching placement strategy. We observe that users moving at either a very low or very high speed should cache the most popular files, while users moving at a medium speed should cache less popular files to avoid duplication.

Original languageEnglish
Article number7932468
Pages (from-to)5001-5015
Number of pages15
JournalIEEE Transactions on Wireless Communications
Issue number8
Publication statusPublished - Aug 2017
Externally publishedYes


  • Caching
  • device-to-device communications
  • human mobility
  • matroid constraint
  • submodular function

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics

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