Push-and-track: Saving infrastructure bandwidth through opportunistic forwarding

Abstract

Major wireless operators are nowadays facing network capacity issues in striving to meet the growing demands of mobile users. At the same time, 3G-enabled devices increasingly benefit from ad hoc radio connectivity (e.g., WiFi). In this context of hybrid connectivity, we propose Push-and-track, a content dissemination framework that harnesses ad hoc communication opportunities to minimize the load on the wireless infrastructure while guaranteeing tight delivery delays. It achieves this through a control loop that collects user-sent acknowledgements to determine if new copies need to be re-injected into the network through the 3G interface. Push-and-Track is flexible and can be applied to a variety of scenarios, including periodic message flooding and floating data. For the former, this paper examines multiple strategies to determine how many copies of the content should be injected, when, and to whom; for the latter, it examines the achievable offload ratio depending on the freshness constraints. The short delay-tolerance of common content, such as news or road traffic updates, make them suitable for such a system. Use cases with a long delay-tolerance, such as software updates, are an even better fit. Based on a realistic large-scale vehicular dataset from the city of Bologna composed of more than 10,000 vehicles, we demonstrate that Push-and-Track consistently meets its delivery objectives while reducing the use of the 3G network by about 90%. $ This article is an expanded version of work presented at the 12 th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM 2011) [1]. This paper provides greater details and presents all-new results based on different scenarios (e.g., floating data), and different assumptions (e.g, vehicle participation ratio).

DROid: Adapting to individual mobility pays off in mobile data offloading

“…The distribution of contact duration is exponential. Most contacts are very short [6], confirming the highly dynamic nature of the dataset. Only few contacts last for more than a few minutes.…”

“…DROiD anticipates and avoids the insurgence of long-lasting plateaux in the content diffusion through its reactive strategy. This is not the case in other strategies such as Push-andTrack, in which the offloading agent makes the re-injection decision according to the distance between the instantaneous infection ratio and a fixed a priori target objective function [6]. Re-injection decisions do not take into account the general evolution of the infection, but only its instantaneous values.…”

“…1. Thanks to its adaptive re-injection strategy, DROiD leads to much better performance than existing strategies that are bounded to an objective function that remains fixed during the entire offloading process [6].…”

A joint multicast/D2D learning-based approach to LTE traffic offloading

“…The above-mentioned works consider only the optimal selection of the initial seeder nodes and not the control of the dissemination process through injections. Whitbeck et al proposed an injection algorithm that follows target objective functions [30]. Some of the authors of the present work proposed a simple re-injection based scheme that takes into account the evolution of the opportunistic dissemination [22].…”

“…Using only opportunistic communications it is thus impossible, in general, to guarantee the maximum reception delays to all the nodes. To achieve guaranteed delivery, we consider an acknowledgment mechanism, and panic zone retransmissions similarly to the proposition in [30]. Accordingly, all UEs that receive the required content send an acknowledgment to the central controller situated at the eNB through LTE.…”