Vehicular ad hoc networks (VANETs) represent promising technologies for improving driving safety and efficiency. Due to the highly dynamic driving patterns of vehicles, it has been a challenging research problem to achieve effective and time-sensitive data forwarding in vehicular networks. In this paper, a Shared-Trajectory-based Data Forwarding Scheme (STDFS) is proposed, which utilizes shared vehicle trajectory information to address this problem. With access points sparsely deployed to disseminate vehicles' trajectory information, the encounters between vehicles can be predicted by the vehicle that has data to send, and an encounter graph is then constructed to aid packet forwarding. This paper focuses on the specific issues of STDFS such as encounter prediction, encounter graph construction, forwarding sequence optimization and the data forwarding process. Simulation results demonstrate the effectiveness of the proposed scheme.

The delay tolerant mobile sensor network (DTMSN) is a new type of sensor network for pervasive information gathering. Although similar to conventional sensor networks in hardware components, DTMSN owns some unique characteristics such as sensor mobility, intermittent connectivity, etc. Therefore, traditional data gathering methods can not be applied to DTMSN. In this paper, we propose an efficient motion tendency-based data delivery scheme (MTAD) tailored for DTMSN. By using sink broadcast instead of GPS, MTAD obtains the information about the nodal motion tendency with small overhead. The information can then be used to evaluate the node's effective delivery ability and provide guidance for message transmission. MTAD also employs the message survival time to effectively manage message queues. Our simulation results show that, compared with other DTMSN data delivering approaches, MTAD achieves not only a relatively longer network lifetime but also a higher message delivery ratio with lower transmission overhead and data delivery delay.

The basic operation of delay tolerant sensor network (DTSN) is to finish pervasive data gathering in networks with intermittent connectivity, while the publish/subscribe (Pub/Sub for short) paradigm is used to deliver events from a source to interested clients in an asynchronous way. Recently, to extend a Pub/Sub system in DTSN has become a promising topic. However, due to the unique characteristic of frequent partitioning in DTSN, to extend a Pub/Sub system in DTSN is a considerably difficult and challenging problem, and there is no good solution to it in existing works. To adapt Pub/Sub systems to DTSN, we propose CED, a community-based event delivery protocol. In our design, event delivery is based on several unchanged communities, which are formed by sensor nodes in the network according to their connectivity. CED consists of two components: event delivery and queue management. In event delivery, events in a community are delivered to mobile subscribers once a subscriber comes into the community, for improving the data delivery ratio. The queue management employs both the event successful delivery time and the event survival time to decide whether an event should be delivered or dropped for minimizing the transmission overhead. The effectiveness of CED is demonstrated through comprehensive simulation studies.