Spontaneous subdural hematoma in a multigravida with chronic kidney disease and superadded pre-eclampsia detected by MRI: a case report

Chronic kidney disease and pre-eclampsia are both known individual culprits for significant morbidity and mortality of mother and child worldwide. Non traumatic spontaneous subdural hematoma in pregnancy is a rare scenario, however stage 5 chronic kidney disease with superadded pre-eclampsia can be contributory factor for spontaneous extra axial bleed. Our patient was 25-year-old with history of end stage renal disease and chronic hypertension admitted with superadded pre-eclampsia. She had 1 living issue and 2 stillbirths. There was sudden deterioration of mental status as well as motor performance, the patient turned stupurous and was not following verbal commands. Patient was sent for MRI evaluation of brain and diagnosed as right sided subdural hematoma with significant midline shift towards the contralateral side. No intraparenchymal haemorrhage was noted

LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15. 4 Cluster-Tree-Based IoT Applications

[EN] The IEEE 802.15.4 standard is one of the most widely used link layer technology for building Internet of Things (IoT). It specifies several physical layer options and MAC layer for meeting low-power and low-rate requirements of devices deployed in a network of IoT. The standard also specifies a synchronization scheme for devices connected in a star topology, operating in beacon-enabled (BE) mode using periodic beacons. The BE mode facilitates synchronization among devices for data transmission and is suitable for large networks to establish low duty-cycles. Absence of a such a scheme for a cluster-tree network has confined its application only to nonbeacon mode. The challenge here is to schedule beacon frame transmissions of multiple devices in a nonoverlapping manner to avoid beacon collisions. This paper tackles the problem of synchronization by proposing localized beacon synchronization (LBS) scheme, a distributed technique for beacon scheduling in cluster-tree network topologies. LBS uses 2-hop information and association order to compute beacon transmission offsets that better utilize the available time slots, incur fewer transmissions, and is highly scalable. Further, we analytically show that the schedulability of the proposed scheme is higher compared to other related schemes. In addition, we also address the important issue of resynchronization that has been ignored in all of the prior works. The proposed resynchronization mechanisms consider the interdependencies between synchronization and duty-cycling schemes and are shown to significantly lower the synchronization overhead when synchronization among devices is lost.This work was supported by the Science and Engineering Research Board, Department of Science and Technology, Govt. of India, under Grant ECR/2016/001651.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2019). LBS: A Beacon Synchronization Scheme With Higher Schedulability for IEEE 802.15. 4 Cluster-Tree-Based IoT Applications. IEEE Internet of Things. 6(5):8883-8896. https://doi.org/10.1109/JIOT.2019.2924317888388966

DADC: A Novel Duty-cycling Scheme for IEEE 802.15.4 Cluster-tree-based IoT Applications

[EN] The IEEE 802.15.4 standard is one of the widely adopted specifications for realizing different applications of the Internet of Things. It defines several physical layer options and Medium Access Control (MAC) sublayer for devices with low-power operating at low data rates. As devices implementing this standard are primarily battery-powered, minimizing their power consumption is a significant concern. Duty-cycling is one such power conserving mechanism that allows a device to schedule its active and inactive radio periods effectively, thus preventing energy drain due to idle listening. The standard specifies two parameters, beacon order and superframe order, which define the active and inactive period of a device. However, it does not specify a duty-cycling scheme to adapt these parameters for varying network conditions. Existing works in this direction are either based on superframe occupation ratio or buffer/queue length of devices. In this article, the particular limitations of both the approaches mentioned above are presented. Later, a novel duty-cycling mechanism based on MAC parameters is proposed. Also, we analyze the role of synchronization schemes in achieving efficient duty-cycles in synchronized cluster-tree network topologies. A Markov model has also been developed for the MAC protocol to estimate the delay and energy consumption during frame transmission.This work is supported by Science and Engineering Research Board, Department of Science and Technology, Government of India under ECR 2016, Grant No. 2016/001651. This work has been partially supported by the "Ministerio de Economia y Competitividad" in the "Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia," "Subprograma Estatal de Generacion de Conocimiento," within the project under Grant No. TIN2017-84802-C2-1-P. This work has also been partially supported by European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) Project ERANETMED3-227 SMARTWATIR.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2021). DADC: A Novel Duty-cycling Scheme for IEEE 802.15.4 Cluster-tree-based IoT Applications. ACM Transactions on Internet Technology. 22(2). https://doi.org/10.1145/3409487S22

A Performance-to-Cost Analysis of IEEE 802.15.4 MAC With 802.15.4e MAC Modes

[EN] The IEEE 802.15.4 standard is one of the widely adopted networking specification for Internet of Things (IoT). It defines several physical layer (PHY) options and medium access control (MAC) sub-layer protocols for interconnection of constrained wireless devices. These devices are usually battery-powered and need to support requirements like low-power consumption and low-data rates. The standard has been revised twice to incorporate new PHY layers and improvements learned from implementations. Research in this direction has been primarily centered around improving the energy consumption of devices. Recently, to meet specific Quality-of-Service (QoS) requirements of different industrial applications, the IEEE 802.15.4e amendment was released that focuses on improving reliability, robustness and latency. In this paper, we carry out a performance-to-cost analysis of Deterministic and Synchronous Multi-channel Extension (DSME) and Time-slotted Channel Hopping (TSCH) MAC modes of IEEE 802.15.4e with 802.15.4 MAC protocol to analyze the trade-off of choosing a particular MAC mode over others. The parameters considered for performance are throughput and latency, and the cost is quantified in terms of energy. A Markov model has been developed for TSCH MAC mode to compare its energy costs with 802.15.4 MAC. Finally, we present the applicability of different MAC modes to different application scenarios.This work was supported in part by the SERB, DST, Government of India under Grant ECRA/2016/001651.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2020). A Performance-to-Cost Analysis of IEEE 802.15.4 MAC With 802.15.4e MAC Modes. IEEE Access. 8:41936-41950. https://doi.org/10.1109/ACCESS.2020.2976654S4193641950

A Beacon and GTS Scheduling Scheme for IEEE 802.15.4 DSME Networks

[EN] The IEEE 802.15.4 standard is one of the widely adopted networking specification for realizing different applications of Internet of Things (IoT). It defines several physical layer options and medium access control (MAC) sublayer protocols for low-power devices supporting low-data rates. One such MAC protocol is the deterministic and synchronous multichannel extension (DSME), which addresses the limitation on the maximum number of guaranteed time slots (GTSs) in 802.15.4-2011 MAC, and provides channel diversity to increase network robustness. However, beacon scheduling in peer-to-peer networks suffers from beacon slot collisions when two or more coordinators simultaneously compete for the same vacant beacon slot. In addition, the standard does not explore DSME-GTS scheduling (DGS) across multiple channels. This article addresses the beacon slot collision problem by proposing a nonconflicting beacon scheduling mechanism using association order (AO). Furthermore, a distributed multichannel DSME-GTS schedule is proposed that optimally assigns DSME-GTSs across different channels. The objective is to minimize the number of times-lots used while maximizing the usage of available channels. Through simulations, the proposed mechanisms' performance is analyzed in terms of energy efficiency, transmission overhead, scheduling efficiency, throughput, and latency and is shown to outperform the other existing schemes.Choudhury, N.; Matam, R.; Mukherjee, M.; Lloret, J. (2022). A Beacon and GTS Scheduling Scheme for IEEE 802.15.4 DSME Networks. IEEE Internet of Things. 9(7):5162-5172. https://doi.org/10.1109/JIOT.2021.3110866516251729