Our main results Constant-factor gap between the lower bound (rib)and the achievable (upper) bound(rub)of the expected backhual transmission rate Rb≤87Rb+2□R2b≤55Rb The achievable bound (rub) is attained by a simple coded Popularity caching scheme similar to [iet al 14 Perform coded caching only among the most popular KM Files However, all N, popular files are N1 File treated uniformly Index The key step is to show a matching lower bound Arbitrary Popularity Distribution! 8Our Main Results • Constant-factor gap between the lower bound (𝑅𝑙𝑏) and the achievable (upper) bound (𝑅𝑢𝑏) of the expected backhual transmission rate: 𝑅𝑢𝑏 ≤ 87𝑅𝑙𝑏 +2 𝑅𝑢𝑏≤ 55𝑅𝑙𝑏 • The achievable bound (𝑅𝑢𝑏 ) is attained by a simple coded caching scheme similar to [Ji et al ’14] – Perform coded caching only among the most popular N1 files – However, all N1 popular files are treated uniformly • The key step is to show a matching lower bound 8 Arbitrary Popularity Distribution! File Index Popularity 1 𝐾𝑀 𝑁1