In this paper, we study the achievable degrees of freedom (DoFs) for K -user multiple-input single-output broadcast channel (BC) in the absence of channel state information at the transmitter under the finite channel coherent time. For the considered K-user BC, a transmitter is equipped with multiple conventional antennas, and receivers are equipped with a reconfigurable antenna that is capable of dynamically modifying the receiving beam radiation pattern. In this system, we propose a blind interference alignment scheme that is able to allocate an asymmetric number of information symbols to each user, which is essentially required to improve DoFs under limited symbol extension. A generalized systematic construction method of transmit beamforming vectors and receiving mode selection patterns to deal with such asymmetric allocation is established. As a consequence, for a broad class of network configurations and symbol extension constraints, the proposed scheme attains an improved sum DoF compared to the previous works, allowing only for the same number of information symbols for all users.
Bibliographical noteFunding Information:
Manuscript received July 15, 2017; revised November 17, 2017 and January 20, 2018; accepted February 9, 2018. Date of publication March 15, 2018; date of current version April 18, 2018. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Rui Zhang. The work of S.-W. Jeon was supported by the Basic Science Research Program through the National Research Foundation of Korea, Ministry of Education, Science and Technology, under Grant NRF-2017R1A2B4012719. The work of D. K. Kim was supported in part by the Institute for Information and Communications Technology Promotion (IITP) grant funded by the Korea government (Ministry of Science and ICT—MSIT) (2015-0-00300, Multiple Access Technique with Ultra-Low Latency and High Efficiency for Tactile Internet Services in IoT Environments) and in part by the IITP grant funded by the Korea government (MSIT) (2016-0-00208, High Accurate Positioning Enabled MIMO Transmission and Network Technologies for Next 5G-V2X (vehicle-to-everything) Services). (Corresponding author: Dong Ku Kim.) H.-S. Cha is with the Advanced Standard Laboratory, LG Electronics, Seoul 150-721, South Korea (e-mail:,firstname.lastname@example.org).
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All Science Journal Classification (ASJC) codes
- Signal Processing
- Electrical and Electronic Engineering