Continuous Evolution of Mobile Communications Technology

Transcription

1 THE INSTITUTE OF ELECTRONICS, IEICE Technical Report INFORMATION AND COMMUNICATION ENGINEERS Mbps Long-Term Evolution LTE 4 LTE-Advanced LTE-A 1 Gbps bps/hz/km 2 5 >1Gbps/ bits/joule 35 5 LTE/LTE-A 5 Continuous Evolution of Mobile Communications Technology Fumiyuki ADACHI Dept. of Communications Engineering, Graduate School of Engineering, Tohoku University Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, , Japan adachi@ecei.tohoku.ac.jp Abstract Mobile communications network has evolved into the 4 th generation (4G) after 35 years from its birth in December of We witnessed the new generation every 10 years. From 1G to 2G, the coverage extension was the most important concern. Between 2G and 3G, there was a big leap in the radio transmission data rate. The major communication service was the voice in 1G and 2G networks. In 3G mobile communications, high speed data communications of up to 2Mbps was targeted. Since the start of 3G services, video communications have been getting popular. In 3.9G LTE and 4G LTE-A, much higher quality video communications and close-to-1gbps broadband data services will become more and more popular. Therefore, the area spectrum efficiency (bps/hz/km 2 ) is a paramount concern. The mobile data traffic volume in 2020 is expected to reach about 1000 times of In 5G, much broader data services (>1Gbps/user) and massive device connections services are expected. Hence, not only the radio energy efficiency (bits/joule) but also the network energy efficiency becomes an important concern. In this paper, we overview the evolution of mobile communications technology over the past 35 years and discuss about the technical issues toward 5G. Finally, we will introduce the distributed antenna cooperative wireless signal transmission techniques which improve simultaneously the spectrum and energy efficiencies while providing seamless connection. Keyword Mobile radio communication, personal mobile communication, LTE/LTE-A, 5G mobile communications system, small-cell network, distributed antenna LTE [1] LTE-Advanced LTE-A 4 This article is a technical report without peer review, and its polished and/or - extended version may be published elsewhere. This article is a technical report without peer review, and its polished and/or extended version may be published Copyright elsewhere by IEICE Copyright 2016 by IEICE

2 [2] kbps Gbps Web 2 TDMA 3 W-CDMA [3] 4 LTE-A 1 3Gbps Gbps 5 [4] [5] 35 5 LTE [6] Service type Voice Multimedia Fixed point-topoint ~1980 0G Voice Low speed data 1G ~2.4kbps Analog AMPS TACS NTT 2G ~64kbps Digital IS95/IS136 GSM PDC Voice High speed data 4G ~30bps/Hz/BS ~300Mbps LTE-A LTE 5G 5G ~14Mbps HSPA 3G ~2Mbps W-CDMA CDMA2000 Voice Broadband data Ultra-high data rate of >> 1Gbps/user Massive device connection Ultra low latency present 2020 Year [7],[8] m km FDMA 2 TDMA 3 CDMA CDMA W-CDMA 5MHz [3] 3 / CDMA Rake / 4 LTE-A 100MHz Rake LTE/LTE-A (IFFT) ZF-FDE OFDMA OFDMA (PAPR) LTE/LTE-A PAPR FDMA SC-FDMA [9] SC-FDMA 12 ZF-FDE FDE MMSE-FDE [10],[11] OFDMA MMSE-FDE W-CDMA LTE

3 1 Time-domain processing 1G FDMA Frequency Frequency f3 f2 f1 2G TDMA ms Time Single-carrier 25kHz Time Ex. 6.25kHz Ex. 5MHz 3G Frequency-domain processing OFDMA/SC-FDMA 3.9G (LTE) Frequency DS-CDMA # 2 # 3 Spreading code# LTE-A 100m km LTE-A CoMP:Coordinated Multi-Point [12] 3 CoMP 5 1 Gbps High speed data area w/o CoMP CoMP uses multiple BSs Core Network 3 CoMP Wireless data traffic Voice<<<Dat a/video 1000 Voice<<Data Continuous technology Voice<Data evolution is necessary in 5G and beyond Technology evolution G/HSPA 3.9G/LTE 4G/LTE-A (14Mbps) (300Mbps) (3Gbps) 5G Time bps/hz/km bits/joule IoT: Internet of Things G 2G 3G 4G 5G Area coverage Spectrum efficiency (capacity) Energy efficiency Radio resource management 5 5 Spectrum and energy efficient gigabit wireless 3.2. [13] 5 1 [14],[15] [16] 6 Massive MIMO [17] Massive MIMO

4 DAN [18],[19],[20] Massive MIMO Massive MIMO 100m km 4 100MHz Macro-cell BS is the center of cell User-centric smallcell is formed [21] 4.2. TDD 100MHz LTE/LTE-A FDE (TDD) TDD Massive centralized MIMO Pathloss Shadowing loss Fading Massive user access Massive distributed MIMO Pathloss Shadowing loss Fading Near single-user access Near singleuser access macro-cell Channel gain Frequency (MHz) 8 100ns 16 MBS (BBU) Transmit equalization Channel estimation Receive equalization Uplink 9 TDD Uplink TDD Frame Down link time Distribut ed antenna User-centric small-cell macro-cell TRx macro-cell BS(BBU) MBS(BBU) Pool of TRx s TRx controller 7 LTE-A CoMP 5 MIMO MU-MIMO Massive MIMO Transmit processing Mod Mod STBC enc. Transmit filtering Peak suppression IFFT IFFT + CP + CP Optical link Receive signal processing Distributed antenna cooperative signal transmission -CP -CP FFT FFT STBC dec. Receive filtering Blind SLM det. 10 STBC MU-MIMO Demo d

5 SLM UE 2 UE 4 11 PAPR STBC Alamouti [22] STBC STBC FDE STBC FDE UE 6 DA DA UE [23] / FDE STBC MMSE FDE FDE [24] STBC 7 11 UE 4.4. MU-MIMO MU-MIMO UE (IUI) UE (IAI) (ISI) IUI/IAI/ISI [25] SVD [26] (BD) SVD BD-SVD BD SVD MMSE-SVD [27], [28] SLM PAPR SLM [29-30] SLM [30] SLM SLM PAPR 3dB 0 SC 12 SLM Prob. (CUE < abscissa) 1.E+00 1.E-01 OFDMA Macro-cell network SISO macro-cell w/ distributed antenna cooperative transmission (MIMO) Interference-limited condition N c =128,N g =32, N t =4, N r =2 a=3.5, s=7.0db K=10dB, L=16 Uniform PDP Ideal CE, B=100MHz MU-MIMO using joint Tx/Rx filtering STBC diversity 1.E-02 1.E+01 1.E+02 1.E+03 1.E+04 Downlink Downlink capacity capacity per per UE per UE C C UE (Mbps) UE (Mbps/100MHz) UE (Mbps/Hz) 11 PAPR 0.1% (db) N c = 64, N g = 16, SRRC filtering (α=0) Random binary phase rotation OFDM using FD-SLM 4QAM 16QAM 64QAM SC-FDE using FD-SLM 5 SC-FDE using TD-SLM No. of phase rotation patterns, U 12 SLM LTE-A

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