Design of a QoS-aware Routing Mechanism for Wireless Multimedia Sensor Networks Md. Abdul Hamid, Muhammad Mahbub Alam, and Choong Seon Hong Networking Lab, Department of Computer Engineering, Kyung Hee University, Korea 446-701 Email: {hamid, mahbub}@networking.khu.ac.kr, cshong@khu.ac.kr Abstract—In wireless sensor networks, majority of routing protocols considered energy efficiency as the main objective and assumed data traffic with unconstrained delivery requirements. However, the introduction of image and video sensors demands certain quality of service (QoS) from the routing protocols and underlying networks. Managing real-time data requires both energy efficiency and QoS assurance in order to ensure efficient usage of sensor resources and correctness of the collected information. In this paper, we present a novel QoS-aware routing protocol to support high data rate for wireless multimedia sensor networks. Being multi-channel multi-path the foundation, the routing decision is made according to the dynamic adjustment of the required bandwidth and path-length-based proportional delay differentiation for real-time data. The proposed protocol works in a distributed manner to ensure bandwidth and end- to-end delay requirements of real-time data. At the same time, the throughput of non-real-time data is maximized by adjusting the service rate of real-time and non-real-time data. Results evaluated in simulation demonstrate a significant performance improvement in terms of average delay, average lifetime and network throughput. I. I NTRODUCTION This paper aims at designing a novel quality of service (QoS) aware packet delivery technique to support high data rate and delay requirements for wireless multimedia sensor networks (WMSNs). The promising pace of technological growth has led to the design of sensors capable of sensing and producing multimedia data. However, as the multimedia data contain images, video, audio and scalar data, each merits a different metric. In order to accommodate high data rate, the design of an efficient routing protocol is of primary interest. The essence of such a protocol emerges due to few challenging and motivating reasons. First, existing data rates of about 40 kbit/s and 250 kbit/s supported by the MICA2 and MICAz sensor motes are not geared to support multimedia traffic [1]. Beside the hardware improvement and associated cost, an alternate approach is to efficiently utilize the available bandwidth by using multiple channels in a spatially overlapped manner to support multimedia applications. Second, the use of multi-path leverages two things: (1) load may be balanced for not to overwhelm the limited buffers at the intermediate sensor nodes, and (2) one path condition may not permit high data rate for the entire duration of the event being monitored. Hence, by allowing multiple paths, the effective data rate at each path gets reduced and the application can be supported. This paper presents a protocol that targets the application of WMSNs where sensors produce multimedia contents form the deployed area to deal with both critical and general data. Applications may include monitoring of a volcano explosion, toxic gases or a forest fire, sniper or enemy detection, detection of the location of survivors for rescue services. Once a node detects an important event, fast and reliable delivery is required since late or failed delivery may cause severe disaster. In real- time applications, such as multi-media streaming, delivered data can become useless by only a few milliseconds. Though current sensor networks use single channel, a sig- nificant number of present sensor node prototypes use radio modules capable of transmitting on multiple channels. For ex- ample, radio capabilities of MICAz mote [2] can communicate on multiple channels as specified in the 802.15.4 standard. The idea of using multiple channels in wireless networks is not new. [3] studies how the capacity of a static multi-channel network scales as the number of nodes increases in the net- work. Authors show that it may be possible to build capacity- optimal multi-channel networks with as few as one interface per node. Authors in [4] present a multi-channel defense mech- anism against jamming attacks in wireless sensor networks by automatically assigning different channels to nodes in the jammed area in order to defeat an attacker. [5] introduces a control-theoretic approach to maximize throughput in multi- channel sensor networks by choosing node’s communication frequencies. Classical multi-path routing has been explored for two reasons: (1) load-balancing in which traffic is split across multiple disjoint paths, and (2) reliable data delivery in which multiple copies of a packet are sent along different paths. While a plethora of techniques have been developed for sensor networks, all protocols featured either the concept of multi- path or multi-channel assumption. QoS provisioned routing protocol with the efficient use of both multi-path and multi- channel for WMSNs has not been addressed. We devise a packet delivery mechanism over multi-path multi-channel provisioned WMSN in which sensors ubiquitously retrieve multimedia contents from the environment. Our major goal is to support high data rate while keeping the attainable delay so that packets can be delivered to the destination with their bandwidth and delay requirements. More specifically, multi-path multi-channel lay the foundation on which routing decisions for real-time and non-real-time traffics are taken using the dynamic bandwidth adjustment and path-length- based proportional delay differentiation (PPDD) techniques. To meet the bandwidth requirements, the proposed technique This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the IEEE "GLOBECOM" 2008 proceedings. 978-1-4244-2324-8/08/$25.00 © 2008 IEEE.