Cache-aided cooperation with no CSIT

Cache-aided Cooperation with No CSIT

Eleftherios Lampiris, Jingjing Zhang, Petros Elia EURECOM, France

Assumptions

• No backhaul during content delivery

• Topology: Weak and Strong Interference

• No CSIT: Blindly Harness Topology

• Content: Partially close, partially far

Key Questions

•What’s the role of Tx Caching?

– Content Closer, Cooperation, Boost Rx caching

•What’s the role of Rx Caching?

– Use unwanted movies to remove interference

• Topology : Friend or Foe?

– Interference Enhancement Result

T (γ_T ,γ_R) = K ^γ_T (1 − γ_R) K(1−τ )+ (Kγ_R+1)

(

min{₁^2τ₋⁻_γT¹, τ }⁾⁺

+ K(1−γ_T )(1−γ_R)

K_g min

{ τ

1−γ_T , 1

} x_s

• Transmitter Side Caching

• Interference Enhancement

• Coded Caching

Cache at the Edge

•Tx caching for variable Rx caching

•A lot of Tx caching needs no Rx caching

Kγ_R = 0 Kγ_R = 1 Kγ_R = 2 Kγ_R = 10 Kγ_R = 20

0.1 0.3 0.5 0.7 0.9 150

250 350

0 γ_T

T

50

Cache at the Users

•Tx caching for variable Rx caching

•Even a little Rx caching can do a lot

150 250 350

0

Kγ_T = 1 Kγ_T = 20 Kγ_T = 80

0.04 0.08 0.12 0.16 γ_R T

50

Take home message

•Tx & Rx caching complement each other

•Adding backhaul can help increase per- formance

References

[1] I. Maric, R. Dabora, and A. J. Goldsmith, “Relaying in the presence of interference:

Achievable rates, interference forwarding, and outer bounds,” IEEE Transactions on Information Theory, 2012.

[2] A. G. Davoodi and S. A. Jafar, “Generalized DoF of the symmetric K-user Interfer- ence Channel under finite precision CSIT,” in IEEE International Symposium on Information Theory (ISIT), 2016.

[3] M. A. Maddah-Ali and U. Niesen, “Fundamental limits of caching,” IEEE Trans- actions on Information Theory, 2014.

[4] E. Lampiris, J. Zhang, and P. Elia, “Cache-aided cooperation with no CSIT,” in IEEE International Symposium on Information Theory (ISIT), 2017.