A Lightweight Temperature Scheduling Routing Algorithm for an Implanted Sensor Network Rossi Kamal, Md. Obaidur Rahman and Choong Seon Hong Computer Engineering Kyung Hee University Email:(rossi,rupam)@networking.khu.ac.kr, cshong@khu.ac.kr Abstract—Modern diagnosis system has been evolved to equip human being with advanced health-service. In vivo sensors have come up to contribute in this field with its support in miniature, complex operation as implanted in a human body. Implanted sensor solutions like artificial retina, pacemaker and implanted cardioverter defibrillators, insulin pump, glucose monitor- are remarkable inventions in medical science. But, these implanted sensor nodes exhibit temperature at packet transmission or processing time that can be dangerous for surrounding human tissues. With the advancement of wireless communication and sensor network technology, thermal aware routing algorithms have been proposed for this type of sensor network. But, these algorithms suffer from disadvantages like hotspot creation, com- putational complexity overhead or redundant hop traversal etc. We also have to consider energy constraints like limited battery life of this miniature form of sensor nodes. We have tried to solve these problems with lightweight event-based communication (publish-subscribe system) in this type of sensor network. We have proposed a lightweight temperature scheduling routing algorithm for this implanted sensor network. Proposed routing protocol is considered to schedule temperature in implanted sen- sor nodes deployed in the joint operation of cancer hyperthermia, radio-therapy and chemo-therapy. I. I NTRODUCTION Body sensor networks [1] have the potential to change the medical diagnosis system [2][3][4][5]. One example of it is smart implanted sensor node that is deployed in artificial retina, glucose monitoring, insulin pumps, blood pressure monitoring etc [6][7][8][9] (Fig. 1) . Implanted sensor nodes generate temperature when they transmit or process packets [6]. In long term monitoring, these generated heat can be very harmful for patients. Also, these nodes are powered by battery which is recharged by IR (infrared ray). The more the IR is exhibited; human tissue becomes sensitive for bacterial attack. Existing thermal aware routing algorithms[10][11][8][12][7] for implanted sensor nodes suffer from problems like hotspot creation, packet delivery delay, maximum hop or computa- tional complexity. Existing communication protocols for sen- sor network (for example: directed diffusion [13],omniscient multicast or flooding techniques [14] [15]) are not also appli- cable to this type of network [16] [17]. We have proposed a lightweight rendezvous algorithm (LR) [section 3] to schedule temperature in an implanted sensor network. With this algorithm, nodes are divided into small clusters. In each cluster, nodes are subscribed to tempera- ture increasing event. By performing services (temperature or blood pressure sense etc), when a node’s temperature is Cochlear Implants Gastric Stimulators Deep Brain Neurostimulators Cardiac Defibrillators/ Pacemakers Insulin Pumps Foot Drop Implants Fig. 1. Implanted Sensor Network increased above a threshold value, it stops that service. It also immediately contacts corresponding subscriber (through broker) to start that service. In our example scenario, LR schedules temperature for in-vivo sensor nodes deployed for the joint operation of hyperthermia, radiotherapy and chemotherapy in cancer treatment [18]. II. MOTIVATION FOR LIGHTWEIGHT TEMPERATURE SCHEDULING ROUTING FOR AN I MPLANTED SENSOR NETWORKS With the advancement of smart implanted sensor nodes and wireless technology, communication protocols have also been proposed for temperature scheduling in an implanted sensor network. These protocols namely thermal aware rout- ing algorithms suffer from limitations like hotspot creation, complexity overhead or event maximum hot traversal etc. These limitations motivated us toward an alternative solution- a lightweight event based approach to schedule temperature in an implanted sensor network.. TARA [10] was an early approach on thermal aware routing for implanted a sensor network. It is a routing protocol that sends packet by following a withdrawal strategy. If defines a hotspot region that is above a threshold value of temperature. When a node sends a packet to a hotspot, it withdraws from it and the packet is back to the sender. After the cooling period, the packet is sent again