Sensors_**2011**, _11_, 111-137; doi:10.3390/s110100111  
_Sensors_  
**ISSN 1424-8220**  
www.mdpi.com/journal/sensors  
_Article_  
**Energy-Efficient Receiver-Driven Wireless Mesh Sensor Networks**  
**[PERSON] \({}^{1,\star}\), [PERSON] \({}^{2}\), [PERSON] \({}^{1}\) and [PERSON] \({}^{3}\)**  
\({}^{1}\) Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka,  
Suita-shi, Osaka 565-0871, Japan  
\({}^{2}\) School of Comprehensive Rehabilitation, Osaka Prefecture University, 3-7-30 Habikino,  
Habikino-shi, Osaka 583-8555, Japan  
\({}^{3}\) Fuji Electric Systems, 1 Fujicho, Hino-shi, Tokyo 191-8502, Japan  
\({}^{\star}\) Author to whom correspondence should be addressed; E-Mail: [EMAIL_ADDRESS]. _Received: 18 November 2010; in revised form: 14 December 2010 / Accepted: 15 December 2010 / Published: 23 December 2010_  
**Abstract:** A major challenge in wireless sensor networks research is energy efficiency. In the intermittent receiver-driven data transmission (IRDT) protocol, which aims at saving energy, communication between two nodes commences when multiple receiver nodes transmit their own IDs and the sender nodes receive them. This protocol can be used to construct a mesh network which is robust against node failure and wireless channel fluctuations. In our work, we improve this protocol by implementing a collision avoidance method for control packets. First, we refer to the probability of control packet collision as a function of the intermittent interval. We then introduce procedures to determine the interval which decreases or minimizes this probability. Afterwards, we include a data aggregation mechanism into IRDT to reduce data transmission frequency and the occurrence of control packet collisions. Through computer simulation, we show that IRDT can offer greater reduction of the average energy consumption compared with RI-MAC and X-MAC, especially at small loads, and we also demonstrate that IRDT with collision avoidance for control packets can attain higher performance than the original IRDT. This method ensures a packet collection ratio of more than 99% and an average energy consumption 38% lower than that of EA-ALPL and 90% lower than that of the original IRDT. **Keywords:** sensor network; intermittent operation; simulation; mesh network Introduction  
Recently, due to advances in wireless and micro-electromechanical (MEMS) technologies, extremely small sensor nodes featuring wireless communication facilities have been developed, and as a result wireless sensor networks have received considerable attention. Sensor networks are particularly useful for a wide range of applications as they possess sensing capabilities without the need for implementing a centralized infrastructure. However, some critical technical problems still need to be resolved in wireless sensor networks, one of which is the energy efficiency of sensor nodes with limited battery life. There are various approaches to the improvement of energy efficiency, for example, miniaturization of the sensor nodes, media access control (MAC) with sleep control, and multi-hop routing [1; 2; 3; 4]. In this paper, we use one of the MAC layer approaches, namely, intermittent operation. In particular, considerable amounts of energy can be saved through intermittent operation, in which wireless nodes sleep to save power and wake up periodically to transmit or receive packets. Here, we refer to this wake-up interval as 'intermittent interval'. This power-saving operation is based on the fact that sleeping nodes consume considerably less energy than idling nodes [5]. In intermittent operation, nodes must control wake-up times in order to communicate with each other. Control methods for intermittent operation are classified into two types: synchronous [3; 6; 7] and asynchronous [4; 8; 9; 10]. A synchronous method uses a beacon to maintain synchronization between intermittent operations.