International Journal of Computer Science and Business Informatics IJCSBI.ORG ISSN: 1694-2108 | Vol. 11, No. 1. MARCH 2014 67 Survey of MAC Protocols for Heterogeneous Traffic in Wireless Sensor Networks Sridevi S. Associate Professor, Department of Computer Science and Engineering, Sona College of Technology, Salem, India Priyadharshini R. PG Scholar, Department of Computer Science and Engineering, Sona College of Technology, Salem, India Usha M. Professor & Dean, Department of Computer Science and Engineering, Sona College of Technology, Salem, India ABSTRACT Wireless Sensor Networks (WSNs) consists of multiple sensor nodes, which are deployed randomly to collect periodic data, processes the data and forward it to the sink node. The main challenges that WSN faces are severe energy constraints, robustness, responsiveness, self-configuration, etc… Among this the main challenge is the energy efficiency. In order to tackle all these challenges, new protocols in all the layers of communication stack need to be designed. Designing a MAC protocol is of crucial importance because it influences the transceiver unit of the sensor node. The Quality of Service (QoS) at the MAC layer matters as it rules medium sharing and supports reliable communication. In WSNs nodes generate heterogeneous traffic which have different QoS requirements like reliability and delay deadline with different priority requirements that vary according to the application. In this work, a variety of MAC protocols for WSNs are surveyed, with a special focus on traffic classification and priority assignment. As in the existing TDMA based MAC protocols, only one timeslot is allocated to all the sensor nodes in each frame. But our work is to classify the sensed data according to its priority first and allocate slots variably based on its requirement to be sent to the sink node to perform faster rescue operations. A comparison of different MAC protocols with various parameters and future research directions are also included. Keywords: Wireless Sensor Networks, energy efficiency, MAC protocol, traffic classification, priority assignment