Bundle protocol (BP) is the main protocol of delay/disruption-tolerant networking which is developed to provide reliable data delivery services in a stressed communications environment. A typical ...application of BP is for data delivery in a challenging deep-space communication environment. However, little work has been done in analyzing the performance of BP in deep-space communications, especially in presence of highly channel-rate asymmetry. In this paper, we present analytical modeling of the transmission performance of BP over deep-space communication channels characterized by highly asymmetric channel rates. The model is built to estimate the expected file delivery time (and goodput) of the protocol for reliable data delivery in a deep-space transmission scenario. The model is validated by conducting data transfer experiments using a PC-based experimental test bed.
The delay/disruption-tolerant network (DTN) was proposed as an end-to-end networking architecture for file delivery service in a stressed communication environment. A typical application of DTN ...technology is for reliable data delivery in deep-space vehicle communications. The main protocol of DTN, i.e., bundle protocol (BP), utilizes a store-and-forward mechanism and a custody transfer option for transmission reliability. However, little work has been done on the performance evaluation of DTN's BP in deep-space communications. In this paper, we present a study of the retransmission timeout (RTO) timer setting for the use of BP for reliable file (or data) transmission over a relay-based deep-space vehicle communication infrastructure characterized by extremely long latency, lossy data links, and highly asymmetric channel rates. Unlike most studies proposed for terrestrial Internet for which the RTO timer is set equal to or longer than the round-trip time (RTT), we propose to set the RTO timer shorter than the RTT and expect that it will increase delivery efficiency per unit of time. We intend to find an RTO timer setting for maximum data delivery performance of BP, which is considered to be an optimal RTO timer, for deep-space missions. For the first time, analytical models are built for delivery performance involving the RTO timer. Using the built models, we tune the RTO timer toward the highest data delivery performance. The models are validated by running text file transfer experiments using a PC-based testbed and tuning the RTO timer toward the best performance of BP. A performance comparison between the optimal RTO timer proposed in this study and the existing commonly used RTO timers is also presented.
Delay/disruption tolerant networking (DTN) offers a solution to communications in "challenged" networks. Some work has been seen in evaluating the performance of DTN protocols based on simulated or ...emulated file transfer experiments. However, there is a need for a model of the performance of the DTN Licklider transmission protocol (LTP), which particularly targets reliable data transmission in deep space. In this paper, we present a performance model of LTP-based DTN data transmission in challenging communications characterized by extremely long signal propagation delay, lengthy link disruptions, and highly lossy channels that are typical of deep-space links. The model is verified by file-transfer experiments using a PC-based testbed.
Delay/disruption-tolerant networking was developed to enable automated network communications despite the long link delay and frequent link disruptions that generally characterize deep-space ...communications. It uses the well-known approach of store-and-forward with optional custody transfer, in which a node agrees to hold a file in memory (or storage) until its successful reception is acknowledged by the next node. The performance and memory consumption of delay/disruption-tolerant networking's Licklider transmission protocol (LTP) and bundle protocol in deep space will bear on decisions to adopt this technology. There is currently an urgent need to evaluate the performance and memory dynamics for file transmission by LTP and bundle protocol. In this paper, we present a study of memory dynamics for LTP-based transmission in a typical relay-based deep-space communication system characterized by an extremely long signal-propagation delay, lossy data links, and asymmetric data rates. Analytical models are built to quantify the dynamics of memory occupancy/release and memory release latency imposed by the use of LTP for reliable and complete file delivery in deep-space missions. File-transfer experiments are conducted using a test bed to validate the models.
In this letter, we propose a new approximated basis vector reordering (ABVR) criterion for low-complexity lattice reduction aided (LRA) multiple-input multiple-output (MIMO) detection. Despite the ...approximation, the ABVR criterion is proved to collect the full receiving diversity for LRA linear detection. A variant of the well-known complex Lenstra Lenstra Lovász (CLLL) algorithm, i.e., LLL with deep insertion (DLLL), is employed to accommodate the ABVR criterion (DLLL-ABVR). Compared with the original CLLL and other approximated algorithms, the proposed DLLL-ABVR algorithm largely reduces the number of basis vector reordering (BVR) operations. Simulation results show that, on a practical MIMO scale, the proposed lattice reduction algorithm provides similar detection performance, especially for successive interference cancelation (SIC) detectors, while requiring significantly lower computational complexity.
The performance of delay/disruption tolerant networking (DTN) protocols in cislunar and deep-space communication systems has previously been studied by simulation. However, little work has been seen ...in characterizing in an analytical manner the performance of DTN protocols for space with respect to asymmetric channel rates. We present a performance characterization of the recently developed DTN Licklider transmission protocol (LTP) convergence layer adapter (CLA) (or simply LTPCL) over cislunar space channels with data-rate asymmetry. Analytical models are built to characterize LTPCL with respect to the minimum number of bundle protocol (BP) bundles that should be aggregated to avoid delay in acknowledgment (ACK) transmission and the optimal number of bundles to be aggregated for the best transmission efficiency of BP/LTPCL, with the effect of full overhead at all layers taken into consideration. The models are validated by file transfer experiments running BP/LTPCL protocols using a PC-based testbed.
This letter considers availability maximized ground station (GS) selection for free-space optical (FSO) satellite networks, which is a challenging problem in the area of optical satellite ...communications. As a main contribution of this letter, we propose to address this problem from a new perspective of mathematical optimization. In particular, we advocate a gradient projection based algorithm after performing smoothing and relaxation on the original problem. Simulation results and complexity analysis show that, when compared to the conventional GS selection methods, the proposed scheme achieves a better tradeoff between network availability and computational complexity.
A human localization system using multi-source heterogeneous data in indoor environments is proposed in this paper. The system can be easily constructed with already deployed Wi-Fi and camera ...infrastructures and is able to make use of received signal strength samples, surveillance images, and room map information to achieve a comparable performance. In a corridor scenario, we optimize propagation model (PM) parameters with crowdsourcing data from only several locations and establish a data table of optimized parameters for trilateration localization. These crowdsourcing data are also used to correct trilateration localization results, through which localization performance can be greatly improved. In a room scenario, we locate a human object with a panoramic camera and room map. We first detect the human object on the observed image and search a pixel location that represents the object's location best. Then, the pixel location on the image is mapped to the room map using an artificial neural network. By this method, localization accuracy of sub-meter level can be obtained. We perform the proposed system in our experimental environment, and the experimental results show that our localization system not only requires no extensive time and labor cost, but also outperforms fingerprinting and PM localization systems.
Extensive work has been done in the performance evaluation of delay-/disruption-tolerant networking (DTN) technologies in cislunar and deep-space communications using simulation or emulation file ...transfer experiments. However, little work has been seen for studying in an analytical manner the performance of DTN protocols for space communications characterized by asymmetric channel rates. Accurate estimate of file delivery latency i.e., round trip time (RTT) is essential for efficient transmission control, reliable delivery, and bandwidth usage optimization of a protocol. In this paper, we present a performance analysis of the main DTN convergence layer adapter (CLA), i.e., Licklider transmission protocol (LTP) CLA (LTPCL adapter), over cislunar space channels, focusing on RTT estimates, in the presence of asymmetric channel rates. Analytical models are built for the RTT estimate of LTPCL transmissions with the effect of delay caused by space channel-rate asymmetry, channel impairment, and link disruption taken into consideration. The models are validated by file transfer experiments using a PC-based test bed. It is found that a smaller LTP data block size results in a longer delay in acknowledgement (ACK) transmission and thus a longer RTT. With a block size equal to or larger than a calculated threshold size, the ACK delay is avoided; thus, their RTT is consistently very low, leading to significantly shorter file delivery time and goodput advantage.
Bundle Protocol is the main protocol of delay-/disruption-tolerant networking. Its store-and-forward mechanism and custody transfer option enable it to provide reliable file delivery services in a ...stressed communications environment. A typical application of Bundle Protocol is for data delivery in a deep-space communication environment, which is characterized by an extremely long signal propagation delay. However, little work has been seen in performance of Bundle Protocol transmission in deep-space communications. In this article, we present an overview of file transfer operation and performance of Bundle Protocol over a relay-based deep-space communication infrastructure characterized by highly asymmetric channel rates based on file transfer experiments. An optimal Bundle Protocol bundle size for the best transmission performance is also under investigation in this article.
PDF
