On the Degrees of Freedom of SISO X-Channel with Alternating CSIT

Abstract

In this paper, we establish the degrees of freedom (DoF) of the two-user single input single output (SISO) X-channel with alternating channel state information at the transmitters (CSIT). Three cases are considered for the availability of CSIT; perfect, delayed and no-CSIT. Each state is associated with a fraction of time denoted by ${\lambda }_P,{\lambda }_D$ and ${\lambda }_N$, respectively. We provide new results for DoF of the two-user SISO X-channel when the available CSIT alternates between these three cases under a certain distribution $\Lambda ({\lambda }_P,{\lambda }_D,{\lambda }_N)$. Specifically, we show that the X-channel with alternating CSIT for $\Lambda (1/8,3/8,1/2)$ can achieve $5/4$ DoF. The interesting thing about $5/4$ is that it represents a position of compromise or a middle ground between the channel knowledge that transmitters need to steer interference and the degrees of freedom that the network can achieve. Moreover, $5/4$ is strictly greater than $6/5$ which is the upper bound for the X-channel with \textit{fixed} delayed CSIT.

It is only a draft insha'Allah. arXiv admin note: substantial text overlap with arXiv:1404.6348

References in corpus (1)

• A DoF-Optimal Scheme for the two-user X-channel with Synergistic Alternating CSIT