Collaborative beamforming and dirty paper coding assisted transmission strategy for e-health wireless sensor networks

Abstract

Very recently, the advancements of these years in the realms of sensors, wireless communications, and pervasive computing have been proposed to facilitate the health-care service and/or disaster relief. As essential components of these tele-medical systems, the wireless sensor networks for medical purpose become a growing sub-field in the Wireless and Pervasive Communications, aiming to provide both reliable signal propagation and low network latency for physiological information. However, a substantial number of existing systems reveal that the two merits typically contradict each other, which calls for a reasonable tradeoff between them. In this paper, we propose a novel transmission strategy that allows retransmissions while still maintaining low latency for E-health wireless sensor networks. The newly developed strategy incorporates the techniques of collaborative beamforming (CB) and dirty paper (DP) coding, which simultaneously facilitate a successive information flow and allow timely retransmission of unsuccessfully decoded message. As will be shown in this paper, the two aspects of requirements on E-health sensor networks, i.e. high reliability and low latency, come to a reasonably desirable tradeoff in our CB-DP scheme. Then, we derive an explicit expression of outage probability of this scheme as a function of wireless channel characteristics, the number of participating sensor nodes, transmission power and retransmission power budget. Finally, some numerical results demonstrating the effectiveness of this transmission strategy are also provided.