Multi-user MIMO

About: Multi-user MIMO is a research topic. Over the lifetime, 10265 publications have been published within this topic receiving 227206 citations. The topic is also known as: multi user mimo & MU-MIMO.

MIMO channel feedback protocols

Abstract: Handshaking protocols, techniques, and structures are presented for use in implementing closed loop MIMO using explicit feedback in a wireless network.

Performance evaluation of MIMO systems using dual-polarized antennas

Abstract: Exploiting the radio channel in mobile communications systems in a multiple-input multiple-output (MIMO) manner has been shown to highly increase the system capacity. The access to such a MIMO channel usually involves spatially separated antennas of the same polarization at the transmitter and the receiver side. In this paper, we focus on the potential of dual-polarized antennas in mobile radio systems, which avoid undesired antenna spacings and promise increased system performance for certain environments. Therefore, a channel model is presented for data transmission over Ricean fading channels using antenna arrays with spatially separated antenna elements of the same polarization and spatially separated dual-polarized antenna elements, respectively. The performance of these MIMO channels is evaluated based on multiplexing data streams over the available antenna branches and a joint detection of these data streams at the receiver.

Eight-element antenna array at 3.5 ghz for mimo wireless application

Abstract: A multiple-input-multiple-output (MIMO) antenna array with eight printed coplanar waveguide (CPW)-fed monopole antennas operating at 3.5 GHz (3.4–3.6 GHz) is presented. Each antenna is an Inverted-L (IL) monopole surrounded by a parasitic IL-shorted stripe and attains compact configuration. Both the IL-monopole and parasitic IL-shorted stripe contribute their fundamental resonant modes to operate in the desired frequency band. The neutralization line (NL) and ground middle slot are used for decoupling the antenna elements in the array. The measurement results for the prototype reasonably agree with electromagnetic simulations. Measured results for the proposed MIMO antenna array demonstrate that it has impedance bandwidth more than 200 MHz with (S11 < 6 dB), and with effective antenna decoupling mechanism, the mutual coupling is better than 10 dB for the required band (3.4–3.6 GHz). Also, envelope correlation coefficient (ECC) for the proposed MIMO antenna array is less than 0.2 for any two antennas to realize independent prorogation path for a channel. The average channel capacity of the proposed MIMO antenna array is approximately 35 to 38 bps/Hz for a reference signal to noise ratio (SNR) of 20 dB.

Performance analysis of maximum ratio transmission based multi-cellular MIMO systems

Abstract: In this paper, we analyze the performance of the uplink of multi-cellular MIMO systems in flat Rayleigh fading. There is co-channel interference from users within the same cell as well as from other cell users. I The channel model includes lognormal shadowing and path loss along with power control, resulting in a statistical model for user powers. Consistent with practical scenarios, the co-channel interference is categorized into two groups: intracell interference from users within the same cell as the desired user and intercell interference from outer cell users. We derive a compact, easily computable closed form outage probability expression in the form of finite sums. This expression allows for simpler and faster analysis of various MIMO configurations. It has been shown that using antennas on the receiver side results in better performance, since transmit diversity does not combat interference from same cell users.

20.5 A 40nm dual-band 3-stream 802.11a/b/g/n/ac MIMO WLAN SoC with 1.1Gb/s over-the-air throughput

Abstract: The steep growth of digital-content consumption and increasing reliance on wireless networks has resulted in emerging standards such as IEEE 802.11ac. By employing spatial diversity, Multi-user MIMO and high-density modulation (up to 256-QAM), 802.11ac MIMO radios can provide significantly increased throughput, link robustness, and range while maintaining backward-compatibilities with existing 802.11a/n WLAN [1]. However, wide signal bandwidth and high-density modulation lead to significant challenges in all aspects of RF transceiver design, compared to previous WLAN standards. This paper introduces a fully integrated 3-stream MIMO WLAN SoC that integrates all of the functions of an 802.11a/b/g/n/ac WLAN with a record over-the-air TCP/IP throughput of 1.1Gb/s. The 40nm CMOS SoC integrates dual-band (2.4GHz and 5GHz) RF transceivers, data converters, digital physical layer, media access controller, and a PCI Express Gen-2 interface. The RF transceiver employs an all-digital fractional-N PLL with a record Figure-of-Merit (FoM) of -244dB, a wideband low-impedance bias circuit that minimizes pre-PA driver memory effect for 80MHz signal bandwidth, a dual-band receiver with 3dB/4.3dB NF, and a 5th-order Chebyshev low-pass filter with constant-Gm bias and pre-distorted filter coefficients to support up to 80MHz signal bandwidth.