Linear Degrees of Freedom of the X-Channel With Delayed CSIT

被引:48
作者
Lashgari, Sina [1 ]
Avestimehr, Amir Salman [2 ]
Suh, Changho [3 ]
机构
[1] Cornell Univ, Sch Elect & Comp Engn, Ithaca, NY 14850 USA
[2] Univ So Calif, Dept Elect Engn, Los Angeles, CA 90089 USA
[3] Korea Adv Inst Sci & Technol, Dept Elect Engn, Taejon 305701, South Korea
基金
美国国家科学基金会;
关键词
Delayed effects; channel state information; interference channels; interference suppression; wireless networks; INTERFERENCE ALIGNMENT;
D O I
10.1109/TIT.2014.2307053
中图分类号
TP [自动化技术、计算机技术];
学科分类号
0812 ;
摘要
We establish the degrees of freedom (DoF) of the two-user X-channel with delayed channel knowledge at transmitters [i.e., delayed channel state information at the transmitters (CSIT)], assuming linear coding strategies at the transmitters. We derive a new upper bound and characterize the linear DoF of this network to be 6/5. The converse builds upon our development of a general lemma that shows that, if two distributed transmitters employ linear strategies, the ratio of the dimensions of received linear subspaces at the two receivers cannot exceed 3/2, due to delayed CSIT. As a byproduct, we also apply this general lemma to the three-user interference channel with delayed CSIT, thereby deriving a new upper bound of 9/7 on its linear DoF. This is the first bound that captures the impact of delayed CSIT on the DoF of this network, under the assumption of linear encoding strategies.
引用
收藏
页码:2180 / 2189
页数:10
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