Page 65 - ITU Journal Future and evolving technologies Volume 2 (2021), Issue 6 – Wireless communication systems in beyond 5G era
P. 65
ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 6
switching among multiple RSs are needed. In the REFERENCES
case of Space Division Multiple Access (SDMA), the
proposed system can be extended by introducing [1] Cisco, “Cisco Annual Internet Report
Multi-User (MU) MIMO pre/post coders. Although (2018-2023) White Paper”, Mar. 2020.
the number of RSs per user might be reduced [2] IMT Vision – "Framework and overall
compared with SU-MIMO, the sum rate might be objectives of the future development of IMT
improved if the locations of users separate enough. for 2020 and beyond", Sep. 2015.
Furthermore, inter-user interference can be [3] T. Rappaport, R. W. Heath, Jr., R. Daniels, and
actively reduced by RSs with route and beam J. N. Murdock, Millimeter Wave Wireless
optimization.
Communications, Pearson Education, Inc.,
With respect to the multiple BSs, the proposed 2014.
system can be extended by introducing coordinated
scheduling (UE and RS selection) among multiple [4] K. Sakaguchi, G.K. Tran, H. Shimodaira, S.
BSs. Similarly, with the case of SDMA, inter-user Nanba, T. Sakurai, K. Takinami, I. Siaud, E.C.
interference attached to the different BSs can be Strinati, A. Capone, I. Karls, R. Arefi, and T.
actively reduced by RSs with route and beam Haustein, “Millimeter-wave Evolution for 5G
optimization. As a result, the outage rate at the cell Cellular Networks,” IEICE Trans. Commun.,
edge might be improved due to the appropriate vol. E98-B, no. 3, pp. 338-402, Mar. 2015.
selection of UEs and active reduction of inter-user [5] K. Sakaguchi, R. Fukatsu, T. Yu, E. Fukuda, K.
interference. Mahler, R. Heath, T. Fujii, K. Takahashi, A.
Khoryaev, S. Nagata, and T. Shimizu,
5. CONCLUSION “Towards mmWave V2X in 5G and Beyond to
Support Automated Driving,” IEICE Trans.
In this paper, we proposed a massive analog relay
MIMO system for mmWave communications to Commun., vol. E104-B, no.6, Jun. 2021.
generate an artificial multipath environment for the [6] L. Kong, M. K. Khan, F. Wu, G. Chen, and P. Zeng,
UE by using a massive number of RSs. By using a “Millimeter-wave wireless communications
large number of RSs, the mmWave MIMO for IoT-Cloud supported autonomous
transmission is enabled, and the channel capacity is vehicles: overview, design, and challenges”,
greatly improved. Besides, the proposed system IEEE Commun. Mag., vol .55, no. 1, Jan. 2017.
also makes the mmWave communications in the [7] A. Benjebbour, M. Iwabuchi, Y. Kishiyama, W.
NLOS environment possible. A practical and feasible Guangjian, L. Gu, Y. Cui, and T. Takada,
routing algorithm for deriving multi-hop routes “Outdoor experimental trials of long range
using a large number of RSs was also proposed.
Moreover, a comprehensive system performance mobile communications using 39 GHz”, IEEE
analysis was conducted for verification. The results VTC-Spring, Jun. 2018.
confirm that the proposed multi-hop system can [8] M. Shafi, A. F. Molisch, P. J. Smith, T. Haustein,
dramatically improve system performance and P. Zhu, P. De Silva, F. Tufvesson, A. Benjebbour,
further improve channel capacity compared to the and G. Wunder, “5G: A tutorial overview of
single-hop and w/o hop systems. Furthermore, it standards trails challenges deployment and
was confirmed that the multi-hop relay system can practice”, IEEE J. Sel. Areas Commun., vol. 35,
provide high capacity mmWave communications no. 6, pp. 1201-1221, Jun. 2017.
everywhere in the simulation environment. It is [9] S. Sun, T. S. Rappaport, R. W. Heath, A. Nix, and
noted that the performance of the proposed system S. Rangan, “MIMO for millimeter-wave
could be further improved because the developed wireless communications: beamforming,
routing algorithm did not consider the effect of spatial multiplexing, both?”, IEEE Commun.
spatial correlation between the artificial Mag., vol. 52, issue 12, Dec. 2014.
propagation paths. Although it is expected that the
performance of the proposed system will be [10] D-W. Yue and H. H. Nguyen, "Multiplexing
improved by route selection considering the spatial Gain Analysis of mmWave Massive MIMO
correlation and path gain, there are concerns about Systems With Distributed Antenna
increased control overhead. Therefore, the trade-off Subarrays", IEEE Trans. Veh. Technol., vol. 68,
between the performance and the overhead needs issue 11, Nov. 2019.
to be studied in the future.
© International Telecommunication Union, 2021 53
