Interference‐aware MAC scheduling and admission control for multiple mobile WBANs used in healthcare monitoring

Abstract

In this paper, we address the problem of interference when multiple time division multiple access-based wireless body area networks (WBANs) come in the proximity of one another. We propose a simple solution that creates common non-conflicting schedule between these interfering WBANs. Our proposed scheme allows the reuse of maximum possible time slots among WBANs that are two-hop neighbors of one another. A flow admission control scheme is applied to control the flows during the period of interference. We show that the percentage of flows admitted because of flow control decreases with the increase in the network size and flow rate. We simulated a scenario where WBANs move randomly within a simulation area with a certain speed and meet at a particular point. We show that the signal to interference noise ratio (SINR) value of WBANs changes as long as they are within the transmission range of one another. Also, we show that the exchanges of common schedule (which is dependent on the number of times the SINR value drops below the threshold) are required in order to improve the packet delivery ratio in WBANs. INTERFERENCE-AWARE MAC SCHEDULING IN WBANS1353 the center and a receiver is placed at the center of the circle. The study of performance evaluation is limited to 16 transmitters and do not consider the scalability of the network nodes with the same topology.In the monitoring system, we considered patients carrying wearable systems and can move anywhere in the hospital. Pulse oxymeter is an example of one such wearable system, which can measure the amount of oxygen present in the blood. Medium access by the devices in such wearable systems is one of the important research challenges due to the shortage of available channels and bandwidth in the medical band. It is observed that slot-based medium access control (MAC) protocols are suitable for improved operation and performance, because such protocols require no additional overhead and data load is uniform across the nodes. In the literature, most of implementations of WBAN use the IEEE 802.15.4 standard or its variant for low power consumption [5][6][7]. It considers a star topology, where each sensor node sends traffic to the coordinator (controller) in their own slot time. In [6], Li and Tan proposed a TDMA-based MAC protocol for a wearable system having few sensor devices such as pulse oxymeter and a coordinator. The coordinator of the wearable system is responsible for scheduling and initiation of transmission of the end devices.Wireless body area networks use the 2.4 GHz industrial, scientific and medical (ISM) band for their operation. Because the ISM band is unlicensed, several other wireless devices based on Wi-Fi, Bluetooth, and other BANs share the same frequency band, thereby causing fairly high possibilities of interference. The effect of interference is very serious for patients equipped with BANs, because the devices typically monitor the critical conditions involving instruments for measuring ECG, EEG, and EMG. The seriousness is such that the misin...

Link Scheduling Algorithm with Interference Prediction for Multiple Mobile WBANs

“…In [ 28 ], the adaptive CSMA/CA mechanism is applied at the coordinator to avoid collision, and it achieves good performance in terms of high throughput and low collision rates. Another MAC protocol also derives a TDMA schedule for multiple WBANs [ 29 ]. Thus, it is necessary to consider the group mobility of WBANs in the interference mitigation algorithm.…”

An Interference-Aware Traffic-Priority-Based Link Scheduling Algorithm for Interference Mitigation in Multiple Wireless Body Area Networks

“…This scheduling algorithm does not consider whether a WBAN is severely interfered by neighboring WBANs. An interference-aware MAC [28] was also introduced to mitigate interference in healthcare monitoring. In reference [13], a QoS MAC protocol for multiple WBANs overcomes the inter-WBAN interference caused by WBAN mobility.…”

“…We consider a simulation area of 10 m × 10 m while varying the number of coexisting WBANs as in reference [28]. Initially, all WBANs are uniformly deployed.…”

“…The transmission rate is defined as 240 kbps according to IEEE 802.15.6. For modeling the mobility of WBANs, the typical random waypoint model is used as in reference [28], in which the node speed is less than 2 m/s and the pause time is 30 s. As a result, the inter-WBAN connectivity is dynamically changed during the simulation time. In our simulation, two factors are considered: the number of WBANs and packet outgoing rate at each sensor node.…”

Resource Allocation in Hospital Networks Based on Green Cognitive Radios

“…To mitigate the interference caused by the wireless devices to the bio-medical devices, cognitive radio technology is used in [26]. Interference-aware media access control (MAC) scheduling and admission control for multiple mobile in wireless body area network for e-Health care has been proposed in [27].…”