2016/05/23 by Ahmed Wagdy Shaban, Amr El‐Keyi, Shaban, Ahmed Wagdy +6
Computer Science · Engineering · Mathematics · #Advanced MIMO Systems Optimization #Advanced Wireless Communication Technologies #Cooperative Communication and Network Coding #FOS: Computer and information sciences #Information Theory (cs.IT) #cs.IT #math.IT
paper · pdf · doi:10.48550/arxiv.1605.07069
30 pages, 5 Figures, To be submitted soon isA. A part of this paper was published on IEEE ISIT 2014 and available, arXiv:1404.6348
arxiv created 2016/05/23 · openalex publication_date 2016/05/23 · arxiv updated 2016/05/24 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In this paper, we consider the two-user single-input single-output (SISO) X-channel and K-user SISO X-network in fast fading environment. It is assumed that the transmitters have access to synergistic alternating channel state information (CSI). Specifically, the CSIT alternates between three states, namely, perfect, delayed and no-CSIT, in a certain manner to enable these states to work together cooperatively. These states are associated with fractions of time denoted by λP, λD and λN, respectively. For the two-user X-channel, simple upper bound is developed to prove the tightness of the achievability result of 4/3 DoF under a certain distribution of the availability of three CSIT states for Λ(λP=1/3, λD= 1/3, λN=1/3). For the K-user X-network, it is shown that the sum Degrees of freedom (DoF) is at least 2K/(K + 1), using two-phase transmission schemes over finite symbols channel extension and under the same distribution of the availability of Λ(λP=1/3, λD= 1/3, λN=1/3).This achievability result, can be considered as a tight lower bound, coincides with the best lower bound known for the same network but with partial output feedback in stead of alternating CSIT. Hence, we show that the role of synergistic alternating CSIT with distribution Λ(1/3,1/3,1/3) is equivalent to the partial output feedback. Also, this lower bound is strictly better than the best lower bound known for the case of delayed CSI assumption for all values of K. All the proposed transmission schemes are based on two phases transmission strategy, namely, interference creation and interference resurrection, which exploit the synergy of instantaneous CSI and delay CSIT to retrospectively align interference in the subsequent channel uses.