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Applications of MIMO
Published in Leeladhar Malviya, Rajib Kumar Panigrahi, M.V. Kartikeyan, MIMO Antennas for Wireless Communication, 2020
Leeladhar Malviya, Rajib Kumar Panigrahi, M. V. Kartikeyan
Multi-user MIMO (MU-MIMO): When set of MIMOs (base station) communicates with single or multiple users, it is called MU-MIMO. MU-MIMO provides access to multiple users like orthogonal frequency division multiple access (OFDMA). MU-MIMO started with the fourth generation in the year 2012, with 100 Mbps data rate. Due to multi-user multiplexing, it provides direct gain. MU-MIMO is less affected by channel link loss and mutual coupling issues. MU-MIMO requires perfect CSI to provide capacity gain, multiplexing gain, and high throughput for high SNR conditions. Due to the requirement of CSI, the available channel bandwidth is completely utilized. The space division multiple access (SDMA), massive MIMO, coordinated multi-point MIMO, and ad-hoc MIMO are the distinguished forms of MU-MIMO to offer variety of services to multiple users. MU-MIMO has been integrated with 3GPP and WiMAX standards by the number of companies like Samsung, Ericsson, Nokia, and Intel, etc. MU-MIMO is suitable for less complex mobile phones with less receiving antennas. Enhanced MU-MIMO requires advanced decoding and precoding techniques. MU-MIMO is basically designed for time division duplexing (TDD) and frequency division duplexing (FDD) [37].
Distributed MIMO Network for 5G Mobile Communication
Published in Zoran S. Bojkovic, Dragorad A. Milovanovic, Tulsi Pawan Fowdur, 5G Multimedia Communication, 2020
Rachit Jain, Robin Singh Bhadoria, Neha Sharma, Yadunath Pathak, Varun Mishra
Multiuser MIMO. Unlike the single-user MIMO system, multiuser MIMO provides access to multiple users. MIMO provides higher throughput when signal-to-noise ratio (SNR) is high and also provides capacity gain because multiple users access the channels at the same time. MIMO also permits spatial multiplexing gain at the base station without the need for multiple antennas at the user’s equipment. MIMO is a type of extension of space-division multiple access (SDMA). Capacity benefits of multiuser MIMO are more than the single-user MIMO. [1,3]. The best example to understand multiuser MIMO is as follows: When people order any product from an online shopping website, then to ensure the proper delivery of a product to an intended recipient, seller uses courier service that means sharing the same service. This sharing mechanism saves expenses, provides better utilization of resources and improves experience and services [1]. Multiuser representation is shown in Figure 4.3 for better understanding.
Mainstream WiFi Standards
Published in Mahbub Hassan, Wireless and Mobile Networking, 2022
The race for higher data rates continues. While the goal with 802.11n was to break the 100 Mbps mark, 802.11ac aims to hit the Gbps mark. To achieve this incredible rate at the existing 5 GHz ISM band, 802.11ac basically continues to tighten the 802.11n parameters to squeeze more bits out of the same spectrum. These include more aggressive channel bonding, modulation, spatial streaming, and piloting. A further notable enhancement in 802.11ac [802-11ac] is to enable multi-user MIMO (MU-MIMO), which allows it to benefit from the MIMO technology introduced in 802.11n even when user equipment do not support multiple antennas. We will first examine the parameter updates for data rate increase followed by the discussion on MU-MIMO.
Low power consumption detectors for mmWave massive MU-MIMO-GFDM systems
Published in International Journal of Electronics, 2022
Fang-Biau Ueng, Hsuan-Fu Wang, Bo-Xun Huang
Many standards use the OFDM-based scheme as the physical layer technology. However, there are some problems with the new system that utilises the OFDM for implementing applications, such as Machine-Type communication (MTC) (Ding et al., 2013), Haptic Internet (She & Yang, 2016) and IoT (Internet of Things). MTC is with low power, so OFDM is unbearable due to orthogonal subcarriers. The low-latency requirements in the Haptic Internet require short data bursts. Because there is a cyclic prefix (CP) in an OFDM symbol, OFDM presents disappointing spectral efficiency. The IoT will become popular in the 5 G, which indicates that many devices will connect to the Internet, but spectrum resources are becoming less and less. Segmented spectrum is a solution; for example, unused spectral in the UHF television frequency bands (Tang et al., 2017) is a segmented spectrum. However, difficulties and unavoidably interferences occurred as the signal transmission in the segmented spectrum due to the high out of band emission (OOB) emission of the OFDM scheme (Van De Beek & Berggren, 2008). The GFDM has been proposed to solve the problems in 5 G application scenarios (Michailow et al., 2014). GFDM can obtain high bandwidth efficiency by dividing a high-speed input signal into low-speed symbol streams and transmitting the data streams in parallel through multiple overlapping spectrums (J.-H. Choi et al., 2015). Each GFDM symbol block is composed of many subsymbols and subcarriers. The GFDM, compared with the OFDM, only has fewer cyclic prefixes (CP) required. Hence, the GFDM exhibits high efficiency of transmission in low latency applications such as the haptic Internet. In addition, compared with OFDM signals, GFDM signals have lower PAPR, and this characteristic makes the GFDM is a suitable waveform for MTC transmission. GFDM signals are also constructed by a pulse-shaping filter (Han et al., 2017), which reduces emissions of OOB, making segmented spectrum for IoT feasible in cognitive radio (CR) without disrupting current services severe interference (Zou et al., 2015). The pulse-shaping filter results in non-orthogonal sub-carrier waveforms, followed by inter-symbol interference (ISI) and inter-carrier interference(ICI). A multi-user MIMO (MU-MIMO) communication system can transmit different symbol streams to other destinations simultaneously. All users can share multiplexing gain. High-complexity equipment will exist at the base station, and the user can be achieved by using low-cost and single antenna equipment in this way. The advantage of the MU-MIMO system is that it can increase the data transmission rate, increase energy transmission efficiency and reduce interference.