Mohammad Rajiullah

Dr. Mohammad Rajiullah

Karlstad University, Karlstad, Värmland, Sweden
orcid

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 March 2022 in Data
Verified
Journal Article
Open access
PDF file
UAUsman Ali
Usman Ali
Giuseppe CasoGiuseppe Caso
Giuseppe Caso
Luca De NardisLuca De Nardis
Luca De Nardis
KKKonstantinos Kousias
Konstantinos Kousias
Mohammad RajiullahMohammad Rajiullah
Mohammad Rajiullah
MBMaria Gabriella Di Benedetto
Maria Gabriella Di Benedetto
Understanding radio propagation characteristics and developing channel models is fundamental to building and operating wireless communication systems. Among others uses, channel characterization and modeling can be used for coverage and performance analysis and prediction. Within this context, this paper describes a comprehensive dataset of channel measurements performed to analyze outdoor-to-indoor propagation characteristics in the mid-band spectrum identified for the operation of 5th Generation (5G) cellular systems. Previous efforts to analyze outdoor-to-indoor propagation characteristics in this band were made by using measurements collected on dedicated, mostly single-link setups. Hence, measurements performed on deployed and operational 5G networks still lack in the literature. To fill this gap, this paper presents a dataset of measurements performed over commercial 5G networks. In particular, the dataset includes measurements of channel power delay profiles from two 5G networks in Band n78, i.e., 3.3–3.8 GHz. Such measurements were collected at multiple locations in a large office building in the city of Rome, Italy by using the Rohde & Schwarz (R&S) TSMA6 network scanner during several weeks in 2020 and 2021. A primary goal of the dataset is to provide an opportunity for researchers to investigate a large set of 5G channel measurements, aiming at analyzing the corresponding propagation characteristics toward the definition and refinement of empirical channel propagation models.

11 August 2022 in Future Internet
Verified
Journal Article
Open access
PDF file
UAUsman Ali
Usman Ali
Giuseppe CasoGiuseppe Caso
Giuseppe Caso
Luca De NardisLuca De Nardis
Luca De Nardis
KKKonstantinos Kousias
Konstantinos Kousias
Mohammad RajiullahMohammad Rajiullah
Mohammad Rajiullah
MBMaria Gabriella Di Benedetto
Maria Gabriella Di Benedetto
The successful rollout of fifth-generation (5G) networks requires a full understanding of the behavior of the propagation channel, taking into account the signal formats and the frequencies standardized by the Third Generation Partnership Project (3GPP). In the past, channel characterization for 5G has been addressed mainly based on the measurements performed on dedicated links in experimental setups. This paper presents a state-of-the-art contribution to the characterization of the outdoor-to-indoor radio channel in the 3.5 GHz band, based on experimental data for commercial, deployed 5G networks, collected during a large scale measurement campaign carried out in the city of Rome, Italy. The analysis presented in this work focuses on downlink, outdoor-to-indoor propagation for two operators adopting two different beamforming strategies, single wide-beam and multiple synchronization signal blocks (SSB) based beamforming; it is indeed the first contribution studying the impact of beamforming strategy in real 5G networks. The time and power-related channel characteristics, i.e., mean excess delay and Root Mean Square (RMS) delay spread, path loss, and K-factor are studied for the two operators in multiple measurement locations. The analysis of time and power-related parameters is supported and extended by a correlation analysis between each pair of parameters. The results show that beamforming strategy has a marked impact on propagation. A single wide-beam transmission leads, in fact, to lower RMS delay spread and lower mean excess delay compared to a multiple SSB-based transmission strategy. In addition, the single wide-beam transmission system is characterized by a smaller path loss and a higher K-factor, suggesting that the adoption of a multiple SSB-based transmission strategy may have a negative impact on downlink performance.

13 June 2022 in IEEE Access
Verified
Journal Article
Open access
MAMuhammad Tahir Abbas
Muhammad Tahir Abbas
KGKarl-Johan Grinnemo
Karl-Johan Grinnemo
JEJohan Eklund
Johan Eklund
SAStefan Alfredsson
Stefan Alfredsson
Mohammad RajiullahMohammad Rajiullah
Mohammad Rajiullah
OAOzgu Alay
Ozgu Alay
The Cellular Internet of Things (CIoT), a new paradigm, paves the way for a large-scale deployment of IoT devices. CIoT promises enhanced coverage and massive deployment of low-cost IoT devices with an expected battery life of up to 10 years. However, such a long battery life can only be achieved provided the CIoT device is configured with energy efficiency in mind. This paper conducts a comprehensive survey on energy-saving solutions in 3GPP-based CIoT networks. In comparison to current studies, the contribution of this paper is the classification and an extensive analysis of existing energy-saving solutions for CIoT, e.g., configuration of particular parameter values and software modifications of transport- or radio-layer protocols, while also stressing key parameters impacting the energy consumption such as the frequency of data reporting, discontinuous reception cycles (DRX), and Radio Resource Control (RRC) timers. In addition, we discuss shortcomings, limitations, and possible opportunities which can be investigated in the future to reduce the energy consumption of CIoT devices.

26 June 2023
Verified
Conference Paper
Closed access
Giuseppe CasoGiuseppe Caso
Giuseppe Caso
Mohammad RajiullahMohammad Rajiullah
Mohammad Rajiullah
KKKonstantinos Kousias
Konstantinos Kousias
UAUsman Ali
Usman Ali
Luca De NardisLuca De Nardis
Luca De Nardis
MBMaria Gabriella Di Benedetto
Maria Gabriella Di Benedetto
Fifth Generation (5G) networks have been operational worldwide for a couple of years. To reveal how the 5G system evolution (e.g., changes in network conditions, deployment, and configurations) affects user performance, empirical long-term analyses are required. This paper presents preliminary insights from our ongoing large-scale measurement study of the commercial 5G non-standalone (NSA) networks deployed in Rome, Italy. An initial comparison between the measurements in 2020-2021 vs. 2023 shows a decrease in throughput and latency performance, calling for deeper analyses toward understanding the root causes and deriving proper optimization solutions.

10 September 2023
Verified
Conference Paper
Open access
Mohammad RajiullahMohammad Rajiullah
Mohammad Rajiullah
Giuseppe CasoGiuseppe Caso
Giuseppe Caso
Anna BrunstromAnna Brunstrom
Anna Brunstrom
JKJonas Karlsson
Jonas Karlsson
SAStefan Alfredsson
Stefan Alfredsson
Özgü AlayÖzgü Alay
Özgü Alay
The deployment of 5G networks, including 5G Non-Public Networks (5G-NPNs) for private use in several verticals, is rapidly taking place worldwide. However, deploying these networks in under-served areas, where there may be limited Internet access or wired backhauling capabilities, presents challenges. To address these challenges, there is a growing interest in using Low Earth Orbit (LEO) satellites, such as SpaceX's Starlink, which can provide high-throughput and low-latency Internet access via dense satellite constellations. In this paper, we present CARL-W, the Wireless module of the Communications Advanced Research Laboratory (CARL) at Karlstad University, which combines a 5G-NPN and a Starlink deployment. CARL-W serves as a platform for empirical analyses on both systems, thus contributing to the study of their possible integration. In particular, we outline the CARL-W experimentation framework and provide access to the CARL-W visualization and data exporting platform. We also open-source a 1-month Starlink dataset, facilitating further analyses of this relatively new technology.

14 November 2024 in IEEE Open Journal of the Communications Society
Verified
Journal Article
Open access
Giuseppe CasoGiuseppe Caso
Giuseppe Caso
Mohammad RajiullahMohammad Rajiullah
Mohammad Rajiullah
KKKonstantinos Kousias
Konstantinos Kousias
UAUsman Ali
Usman Ali
NBNadir Bouzar
Nadir Bouzar
MBMaria Gabriella Di Benedetto
Maria Gabriella Di Benedetto
Fifth Generation (5G) systems have been commercially available worldwide for at least a couple of years, with mid-band Non-Standalone (NSA) being the deployment mode preferred by Mobile Network Operators (MNOs). Empirical analyses have provided so far key insights on 5G NSA performance from different perspectives, but most of these works consider short time periods to drive conclusions. In this paper, we investigate the evolution of 5G NSA considering deployment, performance, and services, including positioning. We perform a large-scale measurement campaign in two phases (2021 and 2023), covering six MNOs in two European countries, Italy and Sweden. Our results show significant differences in network deployment and performance, with increasing network density and frequencies but, at times, decreasing downlink throughput performance. For the latter, we identify worse radio coverage and connectivity issues as root causes. By using a standardized methodology, we also evaluate the performance of new services such as real-time gaming and augmented/virtual reality, and reveal that stable 5G connectivity is key to meet their requirements. Similarly, we highlight the negative effects of roaming on performance. Finally, we evaluate 5G fingerprinting positioning systems and show that a higher accuracy is achievable in denser 5G deployments.