Ultra-Reliable Low Latency Communication (URLLC) using Interface Diversity

An important ingredient of the future 5G systems will be Ultra-Reliable Low-Latency Communication (URLLC). A way to offer URLLC without intervention in the baseband/PHY layer design is to use interface diversity and integrate multiple communication interfaces, each interface based on a different technology. In this work, we propose to use coding to seamlessly distribute coded payload and redundancy data across multiple available communication interfaces. We formulate an optimization problem to find the payload allocation weights that maximize the reliability at specific target latency values. In order to estimate the performance in terms of latency and reliability of such an integrated communication system, we propose an analysis framework that combines traditional reliability models with technology-specific latency probability distributions. Our model is capable to account for failure correlation among interfaces/technologies. By considering different scenarios, we find that optimized strategies can in some cases significantly outperform strategies based on $k$-out-of-$n$ erasure codes, where the latter do not account for the characteristics of the different interfaces. The model has been validated through simulation and is supported by experimental results.Comment: Accepted for IEEE Transactions on Communication

Multi-Connectivity Management and Orchestration Architecture Integrated With 5g Multi Radio Access Technology Network

The significant growth in the number of devices and the tremendous boost in network/user traffic types and volume as well as the efficiency constraints of 4G innovations have encouraged industry efforts and also financial investments towards defining, developing, and releasing systems for the fifth generation. The 5G of mobile broadband wireless networks with multiple Radio Access Technologies (Multi-RATs) have actually been designed to satisfy the system and service requirements of the existing as well as the coming applications. The multi-RAT access network is considered the key enabling technology to satisfy these requirements based on low latency, high throughput. To utilize all available network resources efficiently, research activities have been proposed on multi-connectivity to connect, split, steer, switch, and orchestrate across multiple RATs. Recently, multi-connectivity management and orchestration architecture standardization has just started; therefore, further study and research is needed. This project proposed a multi-connectivity management and orchestration architecture integrated with 5G, Long-Term Evolution (LTE), and Wireless LANs (WLAN) technologies. The simulations experiments conducted to measure the Quality of Experience (QoE) by provisioning network resources efficiently, which are: data rate, latency, bit error rate. The results show that the 5G requirements have been achieved with latency and throughput around 1ms and 200 Mbps, respectively

Multi-connectivity between terrestrial and non-terrestrial MIMO Systems

Communicating in a non-terrestrial network (NTN) has recently emerged as a promising technology to provide global seamless connectivity. Although low earth orbit (LEO) satellites in an NTN have been employed for providing ubiquitous coverage and high data rates for ground users, especially in emergent outdoor scenarios, NTN has not been integrated into the design of multi-connectivity for users in a terrestrial network (TN). Inspired by the 3rd Generation Partnership Program (3GPP) suggestion, this paper investigates TN-NTN-combined multi-connectivity downlink multiple-input multiple-output (MIMO) communication system, where each user may simultaneously connect to a base station (BS) in a TN and an LEO satellite in an NTN. Specifically, each user may have four different downlink access modes: served by both an LEO satellite and a BS, served by a BS, served by an LEO satellite, and not scheduled. Zero-forcing beamforming is employed at each LEO satellite to reduce the mutual interference among the satellite’s served users, and maximum ratio transmission beamforming is used at each terrestrial BS to enhance the downlink signal strength. By deriving the probability of each access mode and modeling the interference in such a TN-NTN-combined multi-connectivity MIMO system, we obtain a typical user’s downlink coverage probability and average achievable data rate. Extensive Monte Carlo simulations are conducted to validate our analytical derivations. Simulation results demonstrate that the user’s coverage probability and average achievable data rate can be significantly improved by realizing multi-connectivity with both TN and NTN compared to pure TN or NTN

Reliability-Oriented Intra-Frequency Dual Connectivity for 5G Systems: Configuration Algorithms and Performance Evaluation

User association in wireless networks has historically been done on the basis of single connectivity, i.e. the user equipment (UE) being connected to a single serving access point (AP). Such a design was quite efficient for conventional homogeneous networks with mostly voice-centric applications. However, as networks become more heterogeneous and services become diverse with different performance requirements, connecting to a single AP has proven to be quite inefficientThe 5th Generation (5G) New Radio (NR) interface is expected to continue utilising the existing homogenous networks for some time in the near future serving a wide range of use cases, one of those cases is Ultra-Reliable Low Latency Communications (URLLC) services. For URLLC, short data packets must be correctly transmitted and received within very short latency up to 1ms with a reliability of 99.999%. There are several options being proposed to meet this difficult design target. One very promising suggested solution is the dual connectivity with data duplication, where the same packet is duplicated and independently transmitted via two different nodes. This work uses a system-level simulation to study how the data duplication at PDCP level for dual connectivity is functioning, where every copy of the designated packet is sent via the two connections that a certain User Equipment (UE) is connected. The studied scenario is a homogeneous network of 21 macro cells of 500m inter-site distance. The scenario is first optimized for the single connectivity mode, which supports less than 1Mbps URLLC offered load while meeting the IMT2020 latency requirements. As we enable dual connectivity, in a URLLC traffic only scenario, it is shown that dual connectivity provides some noticeable gain by enabling the support of up to 1.5Mbps URLLC load within the URLLC requirements but not improving the low load criteria in comparison to single connectivity results due to the low interference condition in single connectivity. As a second stage, the gain of DC is studied when the URLLC traffic coexist with a heavy full buffer background eMBB traffic. Results show that a latency gain as well as higher load support than the single connectivity case can be obtained by dual connectivity, however the sensitivity of this gain on the scenario conditions is very high. Finally, an enhanced duplication configuration is added, that is if a packet is successfully sent through one of the links and correctly decoded at the UE, the duplicated copy transmission on the other link is cancelled (i.e. the packet is dropped at the network side). This results in a significant performance improvement in terms of the latency and supported URLLC load especially at relatively high load because it avoids the queuing delay

On Dependable Wireless Communications through Multi-Connectivity

The realization of wireless ultra-reliable low-latency communications (URLLC) is one of the key challenges of the fifth generation (5G) of mobile communications systems and beyond. Ensuring ultra-high reliability together with a latency in the (sub-)millisecond range is expected to enable self-driving cars, wireless factory automation, and the Tactile Internet. In wireless communications, reliability is usually only considered as percentage of successful packet delivery, aiming for 1 − 10⁻⁵ up to 1 − 10⁻⁹ in URLLC

System-Level Analysis of Blockage Dynamics in Millimeter-Wave Communications

The new generation of wireless technology, termed as the fifth generation (5G), introduces a large amount of novel features. An operation in the millimeter-wave (mmWave) spectrum becomes one of those features unlocking a wide bandwidth. The latter allows for a notable increase in the peak data rate by up to tens of gigabits per second and decreases latency to as low as few milliseconds. These improvements provide an opportunity to support high-rate and low-latency applications, such as augmented and virtual reality, eHealth, and many others. Though mmWave communications have great potential, they suffer from severe attenuation caused by signal blockage. In addition to large-scale blockers (i.e., buildings), small-scale blockers such as human bodies bring new challenges to the operation over mmWave bands. Large attenuation losses, as well as the unpredictable mobility of human body blockers, can significantly decrease a service quality when communicating over a mmWave link. Thereby, there is a need to properly model the blockage process, evaluate its impact on mmWave network performance, and estimate performance gains brought by different blockage mitigation techniques. The thesis proposes a mathematical methodology to characterize and evaluate the effect of blockage dynamics in mmWave networks. With the help of stochastic geometry and probability theory, it delivers mathematical models of static and dynamic small-scale blockage, as well as static large-scale blockage. It then introduces system-level performance evaluation frameworks accounting for the main features of mmWave communications, such as blockage and multipath propagation. The mathematical frameworks can also evaluate the impact of several blockage mitigation techniques in realistic deployment scenarios