“…5 Let r b k ,ℓx,0 (d j,ℓx,0 ) denote the distance between BS b k ∈ Φ k (jammer j ∈ Φ J ) and ℓ x,0 . Based on (3), the received signal at ℓ x,0 is given by (4), as shown at the top of this page, where b n,k,0 ∈ Φ n,k,0 denotes the index of the serving BS of the typical user ℓ ,0 in tier k ,0 ∈ K, 6 b n,ke,0 ∈ Φ n,ke,0 denotes the index of an arbitrary BS storing file n in tier k e,0 ∈ K, and (·) T denotes the conjugate transpose operation. Then, the SIR at ℓ x,0 can be expressed as (5), as shown at the top of this page, where I x b n,k x,0…”