Exploring Energy-Latency Tradeoffs for Real-Time Data Gathering in Wireless Sensor Networks

This paper studies the challenging problem of scheduling packet transmissions for data gathering in wireless sensor networks. The focus of our work is to explore the energy-latency tradeoffs in packet transmission using techniques such as modulation scaling. The data aggregation tree – a multiple-source single-sink communication paradigm – is employed for abstracting the packet flow. We consider a realtime scenario in which the data gathering must be performed within a specified latency constraint. We present algorithms to minimize the overall energy dissipation of sensor nodes in the data aggregation tree without violating the latency constraint. For the off-line version of the problem, we propose (a) a numerical algorithm for optimal solutions, and (b) a dynamic programming-based polynormial approximation algorithm by discretizing the transmission time. While interference can be minimized by medium access control (MAC) layer mechanisms, we also illustrate explicit packet scheduling for interference avoidance when multi-packet reception techniques (such as CDMA, FDMA) are used. Moreover, the discretized transmission time naturally leads to a simple, distributed on-line protocol that relies only on the local information available at each sensor node. Extensive simulations were conducted This work is supported in part by NSF grants 0330445, 0325875, and 0347621. A preliminary version of this paper appears in IEEE InfoCom 2004 [1]. This version contains additional content and improvements, including complete proofs, improved on-line protocol, and more comprehensive simulation results.