80 research outputs found
Accuracy vs. Complexity for mmWave Ray-Tracing: A Full Stack Perspective
The millimeter wave (mmWave) band will provide multi-gigabits-per-second
connectivity in the radio access of future wireless systems. The high
propagation loss in this portion of the spectrum calls for the deployment of
large antenna arrays to compensate for the loss through high directional gain,
thus introducing a spatial dimension in the channel model to accurately
represent the performance of a mmWave network. In this perspective, ray-tracing
can characterize the channel in terms of Multi Path Components (MPCs) to
provide a highly accurate model, at the price of extreme computational
complexity (e.g., for processing detailed environment information about the
propagation), which limits the scalability of the simulations. In this paper,
we present possible simplifications to improve the trade-off between accuracy
and complexity in ray-tracing simulations at mmWaves by reducing the total
number of MPCs. The effect of such simplifications is evaluated from a
full-stack perspective through end-to-end simulations, testing different
configuration parameters, propagation scenarios, and higher-layer protocol
implementations. We then provide guidelines on the optimal degree of
simplification, for which it is possible to reduce the complexity of
simulations with a minimal reduction in accuracy for different deployment
scenarios.Comment: 31 pages, 14 figures, 1 table. This paper has been submitted to IEEE
for publication. Copyright IEEE 2020. Please cite it as: Mattia Lecci, Paolo
Testolina, Michele Polese, Marco Giordani, Michele Zorzi, "Accuracy vs.
Complexity for mmWave Ray-Tracing: A Full Stack Perspective.'
Low-Complexity Multi-User MIMO Algorithms for mmWave WLANs
Very high throughput and high-efficiency wireless local area networks (WLANs) have become essential for today's significant global Internet traffic and the expected significant global increase of public WiFi hotspots. Total Internet traffic is predicted to expand 3.7-fold from 2017 to 2022. In 2017, 53% of overall Internet traffic used by WiFi networks, and that number is expected to increase to 56.8% by 2022. Furthermore, 80% of overall Internet traffic is expected to be video traffic by 2022, up from 70% in 2017. WiFi networks are also expected to move towards denser deployment scenarios, such as stadiums, large office buildings, and airports, with very high data rate applications, such as ultra-high definition video wireless streaming. Thus, in order to meet the predicted growth of wireless traffic and the number of WiFi networks in the world, an efficient Internet access solution is required for the current IEEE 802.11 standards.
Millimeter wave (mmWave) communication technology is expected to play a crucial role in future wireless networks with large user populations because of the large spectrum band it can provide. To further improve spectrum efficiency over mmWave bands in WLANs with large numbers of users, the IEEE 802.11ay standard was developed from the traditional IEEE 802.11ad standard, aiming to support multi-user MIMO. Propagation challenges associated with mmWave bands necessitate the use of analog beamforming (BF) technologies that employ directional transmissions to determine the optimal sector beam between a transmitter and a receiver. However, the multi-user MIMO is not exploited, since analog BF is limited to a single-user, single-transmission. The computational complexity of achieving traditional multi-user MIMO BF methods, such as full digital BF, in the mmWave systems becomes significant due to the hardware constraints. Our research focuses on how to effectively and efficiently realize multi-user MIMO transmission to improve spectrum efficiency over the IEEE 802.11ay mmWave band system while also resolving the computational complexity challenges for achieving a multi-user MIMO in mmWave systems.
This thesis focuses on MAC protocol algorithms and analysis of the IEEE 802.11ay mmWave WLANs to provide multi-user MIMO support in various scenarios to improve the spectrum efficiency and system throughput. Specifically, from a downlink single-hop scenario perspective, a VG algorithm is proposed to schedule simultaneous downlink transmission links while mitigating the multi-user interference with no additional computational complexity. From a downlink multi-hop scenario perspective, a low-complexity MHVG algorithm is conducted to realize simultaneous transmissions and improve the network performance by taking advantage of the spatial reuse in a dense network. The proposed MHVG algorithm permits simultaneous links scheduling and mitigates both the multi-user interference and co-channel interference based only on analog BF information, without the necessity for feedback overhead, such as channel state information (CSI). From an uplink scenario perspective, a low-complexity user selection algorithm, HBF-VG, incorporates user selection with the HBF algorithm to achieve simultaneous uplink transmissions for IEEE 802.11ay mmWave WLANs. With the HBF-VG algorithm, the users can be selected based on an orthogonality criterion instead of collecting CSI from all potential users. We optimize the digital BF to mitigate the residual interference among selected users. Extensive analytical and simulation evaluations are provided to validate the performance of the proposed algorithms with respect to average throughput per time slot, average network throughput, average sum-rate, energy efficiency, signal-to-interference-plus-noise ratio (SINR), and spatial multiplexing gain
Reliable and Secure Drone-assisted MillimeterWave Communications
The next generation of mobile networks and wireless communication, including the fifth-generation (5G) and beyond, will provide a high data rate as one of its fundamental requirements. Providing high data rates can be accomplished through communication over high-frequency bands such as the Millimeter-Wave(mmWave) one. However, mmWave communication experiences short-range communication, which impacts the overall network connectivity. Improving network connectivity can be accomplished through deploying Unmanned Ariel Vehicles(UAVs), commonly known as drones, which serve as aerial small-cell base stations. Moreover, drone deployment is of special interest in recovering network connectivity in the aftermath of disasters. Despite the potential advantages, drone-assisted networks can be more vulnerable to security attacks, given their limited capabilities. This security vulnerability is especially true in the aftermath of a disaster where security measures could be at their lowest. This thesis focuses on drone-assisted mmWave communication networks with their potential to provide reliable communication in terms of higher network connectivity measures, higher total network data rate, and lower end-to-end delay. Equally important, this thesis focuses on proposing and developing security measures needed for drone-assisted networks’ secure operation. More specifically, we aim to employ a swarm of drones to have more connection, reliability, and secure communication over the mmWave band. Finally, we target both the cellular 5Gnetwork and Ad hoc IEEE802.11ad/ay in typical network deployments as well as in post-disaster circumstances
Simplified Ray Tracing for the Millimeter Wave Channel: A Performance Evaluation
Millimeter-wave (mmWave) communication is one of the cornerstone innovations
of fifth-generation (5G) wireless networks, thanks to the massive bandwidth
available in these frequency bands. To correctly assess the performance of such
systems, however, it is essential to have reliable channel models, based on a
deep understanding of the propagation characteristics of the mmWave signal. In
this respect, ray tracers can provide high accuracy, at the expense of a
significant computational complexity, which limits the scalability of
simulations. To address this issue, in this paper we present possible
simplifications that can reduce the complexity of ray tracing in the mmWave
environment, without significantly affecting the accuracy of the model. We
evaluate the effect of such simplifications on link-level metrics, testing
different configuration parameters and propagation scenarios.Comment: 6 pages, 6 figures, 1 table. This paper has been accepted for
presentation at ITA 2020. (c) 2020 IEEE. Please cite it as: M. Lecci, P.
Testolina, M. Giordani, M. Polese, T. Ropitault, C. Gentile, N. Varshney, A.
Bodi, M. Zorzi, "Simplified Ray Tracing for the Millimeter Wave Channel: A
Performance Evaluation," Information Theory and Applications Workshop (ITA),
San Diego, US, 202
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