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In this paper, we consider the uplink of cell-free massive MIMO systems, where a large number of distributed single antenna access points (APs) serve a much smaller number of users simultaneously via limited backhaul. For the first time, we investigate the performance of compute-and-forward (C&F) in such an ultra dense network with a realistic channel model (including fading, pathloss and shadowing)...
Multiple receive and transmit antennas can be used to improve the spectral efficiency by transmitting over multiple independent streams. In addition, multiple receive antennas facilitate interference suppression through the use of interference rejection combining receivers. Rank adaptation algorithms are aimed at balancing the trade-off between increasing the spatial gain, and improving the interference...
In this paper, we investigate the energy efficient resource allocation problem for the wireless powered OFDMA multi-cell networks. In the considered system, the users who have data to transmit in the uplink are empowered by the wireless power obtained from multiple base stations (BSs) with a large scale of multiple antennas in the downlink. A time division protocol is considered to divide the time...
MIMO beamforming provides high throughput for WiFi networks, but it also leads to high computation and communication overhead due to Channel State Information (CSI) feedback. Explicit CSI feedback provides high beamforming gains, but it introduces extremely high overhead. Implicit CSI feedback has low overhead, but it provides very low beamforming gains. We propose EliMO to completely Eliminate CSI...
Multiple-input multiple-output (MIMO) communication is an important technique to increase the transmission capacity, but the increased antenna number does not necessarily increase the throughput because of more antenna interference and decoding complexity. An iterative detector-and-decoder (IDD) can effectively improve transmission performance by exchanging reliability information such as log likelihood...
Transmit beamforming and Multi User MIMO (MU MIMO) are key features in the 802.11ac WLAN standard. In this paper, we study these features and analyze the approaches suggested in the literature for enhancing the performance of 802.11ac WLANs using these features.
In massive multiple-input multiple-output (MIMO) systems, superimposed (SP) and time-multiplexed (TM) pilots exhibit a complementary behavior, with the former and latter schemes offering a higher throughput in high and low inter-cell interference scenarios, respectively. Based on this observation, in this paper, we propose an algorithm for partitioning users into two disjoint sets comprising users...
This work explores the theoretical and practical performances of the two most recent IEEE standards, 802.11n and 802.11ac. Experiments were conducted to measure data rates to characterize performance effects of distance and interference between different channels. We conclude that the majority of test cases show 802.11ac achieved higher data rates than its predecessor, as expected. However, performance...
We provide an empirical evaluation of an IEEE 802.11ac Wireless Local Area Network (WLAN) cell with Multiple User Multiple Input Multiple Output (MU-MIMO) technology. We conducted our experiments on a testbed comprising consumer equipment under different office scenarios using 40MHz and 80MHz channels. This is the first performance study of MU-MIMO with 802.11ac in an operational scenario using a...
The current paper deals with application of leaky feeder cables (LFCs) in linear-cells MIMO systems. We first revisit the method whereby we can map the measured channel data to throughput in an LTE system. Later we show that feeding an LFC from its both ends by two independent signals can potentially lead to a promising 2 × 2 MIMO system with a desirable throughput. Our results also interestingly...
The 4:th generation communication standard is constantly evolving with more features being added to the standard specifications. Carrier aggregation and higher order MIMO are examples of features used to support higher data rates. The addition of features puts new requirements on wireless devices and this increasing complexity implies that Over-the-Air testing is more important than ever. At the same...
Dense small-cell deployments of 5G networks require a wireless backhaul to efficiently connect the small cells to the macro base station (BS). We envision a wireless backhaul architecture where cells are grouped into clusters. One small cell per cluster plays the role of a cluster head connecting the rest of the small cells to the macro cell via a mmWave MIMO link. We formulate the problem of jointly...
We evaluate the user rate performance of massive MIMO small cells in hot-spot areas. In particular, with the use of the 28GHz millimeter wave band ray-tracing channel data generated according to the realistic map in Shinjuku, Tokyo, Japan, we investigate the user-specific rates in an area of 150m×120m. The results show promising rate performances with the use of a variety of beamforming schemes in...
Current and future applications impose high demands on software-defined radio (SDR) platforms in terms of latency, reliability, and flexibility. This paper presents a heterogeneous SDR MPSoC with a hexagonal network-on-chip to address these issues. It features four data processing modules and a baseband processing engine for iterative multiple-input multiple-output (MIMO) receiving. Integrated memory...
This paper presents indoor and outdoor experimental results on the achievable throughput for downlink 8-by-16 multi user (MU)-multiple-input multiple-output (MIMO) using 2 sets of user equipment (UE) and carrier aggregation with 8 component carriers in various measurement areas for 5G radio access. In the presence of four centralized antenna units, the throughput performance is evaluated using the...
Cognitive Radio (CR) technology offers a promising solution to the spectrum scarcity problem via Dynamic Spectrum Allocation (DSA). Due to the nature of Cognitive Radio Networks (CRNs), where two networks are active simultaneously, a significant amount of control messaging is required in order to coordinate channel access, schedule sensing, and establish release connections. Efficient Control Plane...
This paper analyses the very high system throughput of IEEE 802.11ac by taking into consideration the key features of MAC and PHY layers under a Multiple In Multiple Out (MIMO) channel. Throughput at the MAC layer is calculated from the transmission probability, contention window and transmission stage. Likewise, the new critical attributes of 802.11ac PHY (i.e. modulation and coding schemes, spatial...
In Cognitive Radio Networks (CRNs), the spectrum underlay approach enables primary and secondary networks to transmit simultaneously, as long as the interference from the secondary network to the primary network is below certain threshold. As the recent advancement of the underlay approach, the transparent coexistence exploiting MIMO interference cancellation was proposed. Previous works assume that...
Targeting the spatial-modulation (SM) MIMO systems, a symbol detector is designed, implemented, and verified. The detector is designed based on a low-complexity dual datapath architecture performing the modified signal-vector-based list detection. Implemented in 0.18μm CMOS, the detector occupies 1.85mm2 and shows the throughput of 686Mbps for 16 × 4 256-QAM SM-MIMO systems. Evaluated under a hardware-in-the-loop...
In this paper, we consider two-hop multi-input multi-output (MIMO) relay wireless systems with energy harvesting. In each hop, transmit antenna selection (TAS)/receive antenna selection (RAS), TAS/maximum ratio combining (MRC), or maximum ratio transmission (MRT)/RAS is employed. Also, a relay harvests energy from the source via either a time switching-based relaying protocol (TSR) or a power splittingbased...
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