Unchaining from the channel: Cooperative computation over multiple-access channels

Motivated by recent work applying lattice codes to physical-layer network coding, we study a system in which the receiver computes a finite-field linear combination of users´ messages. Previous lattice techniques require that the linear combination be closely matched to the channel coefficients in order to achieve a non-trivial computation rate. To overcome this issue, we present a cooperative computation scheme based on a lattice-coding approach to block Markov encoding. In addition to improving the computation rate, the cooperative approach significantly increases the set of linear combinations that can be recovered at the receiver, increasing the flexibility of wireless network-coded systems.