Optimal Scheduling of Content Caching with recommendation and Freshness of Information

• Content caching at the network edge has been considered an effective way of mitigating backhaul load and improving user experience. Caching efficiency can be enhanced by content recommendation and by keeping the information as fresh as possible. To the best of our knowledge, there is no work that jointly takes into account both these aspects in content caching. By content recommendation, a requested content that is not in the cache can be alternatively satisfied by a related cached content recommended by the system. Informationfreshness, arising naturally in content caching can be quantified by age of information (AoI). We address, optimal scheduling of cache updates for a time-slotted system accounting for both content recommendation and AoI, subject to cache capacity as well as backhaul capacity for updating the cache. For each content, there are requests that need to be satisfied and there is a cost function capturing the freshness of information which is monotonically increasing in the AoI. We present the following contributions. First, we prove that the problem is NP-hard even with contents of uniform size. Second, we derive an integer linear formulation for the problem, by which the optimal solution can be obtained for small-scale scenarios. Third, we develop an algorithm based on Lagrangian decomposition. Fourth, we develop efficient algorithms for solving the resulting subproblems. In addition, our algorithm computes a bound that can be used to evaluate the performance of any suboptimal solution. Finally, we conduct simulations to show the effectiveness of our algorithm in comparison to a greedy schedule.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Kommunikationssystem (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Communication Systems (hsv//eng)

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