Abstract
Source nodes in wireless image sensor networks transmit much more information than traditional scalar sensor networks, thereby demanding more energy of intermediate relaying nodes and putting energy efficiency as a key design issue. Intermediate nodes are usually interconnected by error-prone links where bit-errors are common, potentially degrading the application monitoring quality. When reliability is assured by retransmission mechanisms, higher packet error rates do not affect the application quality but result in additional energy consumption due to packet retransmission, even though many monitoring applications can tolerate some loss in the quality of the received image. DWT coding can decompose an image in data subbands, each one with different relevancies for the reconstruction of the original image at the receiver side. We propose an energy-efficient selective hop-by-hop retransmission mechanism where the reliability level of each packet is a function of the relevance of the payload data, according to the resulting subbands and the number of times a 2D DWT is applied over the images captured by the sensors’ cameras. In so doing, some lost packets are not retransmitted, saving energy of intermediate nodes with low impact to the quality of the reconstructed images. In order to estimate the benefits of this tradeoff between energy consumption and image quality, we designed a comprehensive energy consumption model and applied it in extensive mathematic simulations, providing substantial information about the mean performance of the proposed approach when compared with a fully-reliable transmission mechanism.
Highlights
In recent years, Wireless Sensor Networks (WSNs) have raised a lot of attention of the industry and academic communities [1], addressing applications as surveillance, tracking, disaster monitoring, home automation, industrial control, battlefield surveillance, among others
As retransmissions may result in additional end-to-end delay, the authors propose correction mechanisms based on the transmission of redundant packets through multiple paths and the use of Forward Error Correction (FEC) codes, which are computed by each intermediate node instead of only in the source node and in the sink
Considering the context of wireless image sensor networks, we propose a selective hop-by-hop retransmission mechanism that can save energy by avoiding retransmission of some packets by the cost of the quality of the received image at the sink
Summary
Wireless Sensor Networks (WSNs) have raised a lot of attention of the industry and academic communities [1], addressing applications as surveillance, tracking, disaster monitoring, home automation, industrial control, battlefield surveillance, among others. In other words, when the packet error rate increases, more energy consumption is expected due to packet retransmission, but with very low or absent impact in the quality of the visual data received by the sink While such behavior may be acceptable for traditional scalar sensor networks, some visual applications can afford loss in the image quality since the overall energy of the network is preserved. Packets will have different priorities for the applications depending on the carried information, and such priorities may be exploited by cross-layer optimization solutions [10] In such contexts, we propose a DWT-based selective retransmission mechanism where reliable transmission is only assured for the most relevant data to the application, while low relevant packets are not retransmitted if they are discarded due to corruption during transmission.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
