File Delivery Research Articles

On the Performance of Cache-Enabled Hybrid Wireless Networks

To alleviate the backhaul congestion in future hybrid heterogenous networks, this paper investigates the potential benefits of implementing storages in small base stations (SBSs) operating at frequency range 2 (FR2) bands that co-exist with a tier of massive multiple input multiple output (MIMO) macro BSs (MBSs) operating at frequency range 1 (FR1) bands. We develop a unified analytical framework and derive theoretical bounds for such a cache-enabled FR1-FR2 hybrid network under limited backhaul scenario to analyze the exact and approximate latency, average success probability of file delivery, and average data rate considering two open-access user association policies: i) location-based and ii) content-based association. Numerical results demonstrate that wireless edge caching (WEC) can improve the performance of hybrid wireless networks, albeit certain trade-offs, e.g., increasing cache-enabled SBSs cannot always improve the network performance and there exists an optimal SBS density that provides the best latency and throughput performance. Furthermore, we compare the performance of the network with respect to other key network design parameters such as cache size, content popularity, backhaul capacity, and blockages for both the user associations. Our results show that latency under content-based user association is less than that of location-based user association, and although the difference in the average rates under the two user associations is not obvious, content-based association can extricate more backhaul capacity and thus reduce installation cost significantly.

Coded Caching for Time-Varying Files Popularities and Asynchronous Delivery

Data communication has seen exponential growth recently, and it currently dominates wireless communication. As a result, proactive caching was developed to minimize peak traffic rates by storing content, in advance, at different nodes in the network. We consider proactive caching for a broadcast wireless network with one central hub such as a satellite (ST) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> associated mobile units (MUs) such as mobile mini-ground stations or end users. The ST has a library of files, and the MUs demands are assumed to be limited to this library, while the popularity of the library files changes over time. We assume that the MUs demands arrive at different times, and hence, asynchronous file delivery is necessary. We propose a new scheme that minimizes the files delivery sum rate and show that we can use the file delivery messages to proactively and constantly update the MU finite caches. We show that this mechanism reduces the downloaded traffic of the network. The proposed scheme uses index coding to jointly encode the delivery of different demanded files with the cache updates to other MUs to follow the changes in the files popularities. An offline optimization of the delivery sum rate of the scheme is proposed, where it requires knowledge of the files popularities across the whole transmission period. In particular, the problem is formulated as a linear program and the optimal caching is obtained numerically. Moreover closed form solutions to two special cases are derived and a lowerbound to the achievable delivery sum rate is developed. Numerical results show the benefits of the proposed scheme over conventional caching schemes, in terms of reducing the delivery sum rate.

Performance Analysis on Cache-Enabled FR2 IAB Networks

This paper brings the concept of wireless edge caching (WEC) to the realm of integrated access and backhaul (IAB) networks. Traditionally, both access and backhaul are allocated fixed spectrum. However, when WEC is applied to the IAB nodes to pre-fetch some popular files, the backhaul traffic can be drastically reduced. Accordingly, an analytical framework is developed for a cache-enabled IAB network for the wide-band frequency range 2 (FR2) (> 24.25 GHz) channel model. In particular, the optimal spectrum resource allocation policy between access and backhaul for IAB networks is investigated by utilizing WEC. For the considered WEC enabled IAB network, a mathematical framework is presented under the content delivery phase for the calculation of three key performance metrics, namely the average success probability (ASP), throughput, and latency of file delivery with respect to various network parameters such as different caching placement strategies, node density, cache size, antenna number, blockage density, and resource partitioning factor. Extensive numerical results are provided to both verify the theoretical derivations and to demonstrate the precedency of using WEC as a cost-effective measure for the improvement of the IAB network’s performance. In particular, under a normalized cache size of 0.6, compared to the baseline no caching scenario, the percentages of backhaul spectrum that can be saved are 48% (26%), 66% (48%), and 47% (27%) when caching the most popular files (caching uniformly) with respect to the ASP, latency, and throughput of file delivery, respectively. The saved backhaul spectrum can then be shifted to the access for its performance enhancements. Our findings also show that there exists an optimal spectrum partition for IAB with respect to different network parameter settings. Further, there exists a tradeoff in the selection of the optimal partitioning factor with respect to ASP/ throughput and latency of file delivery for varying IAB node densities.

A Reliable Transport Scheme for Human Opportunistic Networks

The human opportunistic networks (ONs) formed by hand-held smart devices can facilitate peer-to-peer communication when humans are on the move, despite contemporaneous end-to-end paths rarely existing. In some scenarios, where network resources, especially power, are scarce and the traffic is large, the data delivery is prone to poor user experience and unbounded delay, although the best effort mechanism “store-carry-forward” is used. To cope with that, most transport/routing schemes obtain an acceptable latency at the cost of energy resources. In real-life human ONs, however, excessive energy consumption will trigger passive participation of the relays in message forwarding, so as to save their limited energy resource. Thus, the reliability of these schemes may get worse in real-life human ONs. In this paper, a reliable transport scheme is developed by making an optimal trade-off between the file round-trip delay and the energy consumption of relays. We make use of acknowledgements and coding at the source to enable successful file delivery. When setting up the network model, the cache management rule referred as “full-duplex” strategy is formulated, and then a mathematical model is established to analyze the proposed scheme. This model describes the evolution of packet dissemination and allows both the mean file round-trip delay and the energy consumption up to the reception of the last acknowledgement by the source to be expressed. Subsequently, a new function based on these two metrics is proposed to reflect the number of files that can be delivered under time and energy constraints. Through optimization procedure, the configurations that can maximize the function are obtained; thus, the optimization of these two metrics is achieved. Numerous simulations and comparisons are conducted and the results verify the accuracy of the analytical model. Comparison results show that with limited energy and passive relays, the proposed transport scheme can significantly reduce the energy consumption of file delivery, which obviously alleviates the selfish behavior of nodes. Therefore, the reliability and stability of the communication service in human ONs are enhanced.

Network evaluation and protocol deployment for complex deep-space networks based on DTN

Previous research on deep-space networks based on delay-tolerant networking (DTN) has mainly focused on the performance of DTN protocols in simple networks; hence, research on complex networks is lacking. In this paper, we focus on network evaluation and protocol deployment for complex DTN-based deep-space networks and apply the results to a novel complex deep-space network based on the Universal Interplanetary Communication Network (UNICON-CDSN) proposed by the National Space Science Center (NSSC) for simulation and verification. A network evaluation method based on network capacity and memory analysis is proposed. Based on a performance comparison between the Licklider Transmission Protocol (LTP) and the Transmission Control Protocol (TCP) with the Bundle Protocol (BP) in various communication scenarios, a transport protocol configuration proposal is developed and used to construct an LTP deployment scheme for UNICON-CDSN. For the LTP deployment scheme, a theoretical model of file delivery time over complex deep-space networks is built. A network evaluation with the method proposed in this paper proves that UNICON-CDSN satisfies the requirements for the 2020 Mars exploration mission Curiosity. Moreover, simulation results from a universal space communication network testbed (USCNT) designed by us show that the LTP deployment scheme is suitable for UNICON-CDSN.

Delay-Oriented Caching Strategies in D2D Mobile Networks

Caching-enabled device-to-device (D2D) networks have the potential to make mobile users directly fetch requested files from nearby users, resulting in low network delay. In addition, user mobility can increase the communication chances among different users, and therefore, the network delay can be further effectively reduced by proper designing the caching strategy. In this paper, mobility-aware caching strategies in D2D networks are studied to minimize the network delay. Specifically, based on the inter-contact user mobility model, the expression of the average file delivery delay is analytically obtained. Considering the limited cache capacity, a delay minimization cache placement problem considering the user mobility is investigated. To optimally solve this nonlinear integer programming problem, we reformulate it as a multistage decision problem. According to the recursive relationship between adjacent stages, dynamic programming is adopted to obtain the optimal mobility-aware caching strategy stage-by-stage. Furthermore, to lower the complexity, we also demonstrate that the original problem can be recasted as a monotone submodular function maximization problem over a matroid constraint. Then, a low-complexity greedy mobility-aware caching strategy with $(1-1/e)$ -optimality performance guarantee is put forward. Numerical results show that, in the scenario with high user mobility, the file delivery delay can be reduced by 47% with our proposed mobility-aware caching strategy, as compared with the most popular caching. Furthermore, the superiority of the proposed caching strategy is verified by real-world data set.

CFDP PDU Tunneling Service over DTN Between Heterogeneous Deep Space Communication Assets

In space exploration missions, the spacecraft have limited computing resources. In particular, the communications environments for these spacecraft, whether in deep space or the cislunar region, are characterized by intermittent connectivity loss, long signal-propagation delay, and high bit-error rates between spacecraft and their ground stations. Delay-Tolerant Network (DTN) has been introduced to enable automated, efficient communication among flight-mission entities in these environments. However, most flight-mission entities are not yet equipped for DTN; a mechanism is needed whereby DTN-enabled entities and non-DTN-enabled entities can easily interoperate. The CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol (CFDP) is supported in both DTN and non-DTN communication fabrics, so perhaps CFDP file transmission can serve as the common communication medium that bridges the two. When CFDP runs without a Bundle Protocol (BP), it requires a more complex CFDP implementation, and multi-hop communication is more difficult to configure. This paper presents a tunneling mechanism that relays CFDP protocol data units (PDUs) between a non-DTN-enabled CFDP entity and a DTN-enabled CFDP entity. This enables CFDP-over-link implementations to bridge into BP networks to simplify multi-hop forwarding through the BP network. A proof-of-concept implementation of the tunneling service has been developed and tested using the Interplanetary Overlay Network (ION) DTN software to evaluate this concept of CFDP PDU relay/forward functionality to enable communication between the two heterogeneous space communication fabrics. Test setup, test results, and future work on the tunneling service are also discussed.

KOMPRESI FILE MENGGUNAKAN ALGORITMA LEMPEL ZIV WELCH (LZW)

In the field of information technology, data communication is closely related to file delivery. The size of the file is sometimes a constraint in the delivery process. Large files will take longer delivery times compared to files with smaller sizes. Therefore, to handle the problem, one of them by means of compression. This study uses an experimental method with a waterfall development model with analysis, design, coding, and testing. This application applies the Ziv Welch Lempel (LZW) algorithm. The Ziv Welch Lemp Algorithm (LZW) is included in the lossless compression technique, which is a compression technique that does not change the original data. The result of a compression assessment used the Lempel Ziv Welch (LZW) algorithm shows the average rate of compression ratio and for all types of text files by 51.04% with an average of 2.56 seconds, for an image file type of 37.26% with an average time of 0.44 seconds. Based on the average percentage of the compression ratio for all file types tested using the LZW algorithm (Lemp Ziv Welch) is 40.40% with an average time required is 1.81 seconds.

Energy and Delay Optimization for Cache-Enabled Dense Small Cell Networks

In Cache-enabled dense small cell networks (DSCNs), energy consumption and file delivery delay are two critical performance metrics. On the other hand, power control is an essential mechanism to mitigate inter-cell interference in DSCNs. However, the impact of power control at small base stations (SBSs) on the system performance when caches are involved has not been well studied. Observing energy consumption and file delivery delay are coupled with each other in cache-enabled DSCNs, different from existing studies, we attempt to optimize these two performance metrics at the same time, taking into account sophisticated power control at SBSs. Firstly, we formulate the energy-delay optimization problem as a utility maximization problem, where cooperative power control among SBSs, file placement and user association are considered. Then, we solve the optimization problem in two stages (i.e., caching stage and delivery stage), based on the fact that caching is performed during off-peak time. At the caching stage, a local popular file placement policy is proposed by estimating user preference at each SBS. At the delivery stage, with given caching status at SBSs, the optimization problem is further decomposed by Benders’ decomposition method. An efficient algorithm is proposed to approach the optimal association and power solution by iteratively shrinking the gap of the upper and lower bounds. Finally, extensive simulations are performed to validate our analytical and algorithmic work. The results demonstrate that the proposed algorithms can achieve a better tradeoff between energy consumption and file delivery delay than the existing algorithms.

Study on Checkpoint Timer Optimal Setup of Licklider Transmission Protocol

As the main data transport protocol of delay/disruption-tolerant networking, Licklider transmission protocol (LTP) is developed to provide reliable and highly efficient data delivery over unreliable deep-space and interplanetary communication channels. For reliable data delivery, a checkpoint (CP) segment of LTP is sent, with a timer set (or, simply, CP timer) to check the arrival status of the entire data block at the receiver, and it is retransmitted upon the expiration of the CP timer prior to reception of an acknowledgment. Little work has been seen in analysis of the CP timer length for optimal performance of LTP in energy-efficient, reliable data delivery. In this article, a packet-level analysis of the CP timer length setting is presented for the reliable data delivery of LTP over unreliable deep-space communication channels based on realistic file transfer experiments conducted using a PC-based testbed. It is our intent to find an optimal CP timer setting so that the reliable file delivery in deep space is ensured with a minimum number of retransmission attempts. By this, the energy-efficient, reliable data delivery of LTP can be achieved in deep-space communications.

Fractional Dynamic Caching: A Collaborative Design of Storage and Backhaul

To reduce the average file delivery time under limited backhaul bandwidth and cache storage, we propose a fractional dynamic caching scheme, that coordinates the utilization of the backhaul and the cache storage. In the proposed scheme, only part of each file is pre-fetched and stored in the static storage segment of small base stations (SBSs), while remaining part of the file will be fetched into the dynamic storage segment when requested by users. We aim to minimize the average file delivery time by investigating the optimal prefetching policy, i.e., the size of the pre-fetched part of each file and the size of the dynamic storage. We formulate the file delivery time minimization problem as a convex optimization formulation. We compute the closed-form of the optimal pre-fetching policy when the wireless rate is constant. Then, a heuristic pre-fetching policy is derived, using the conditional average wireless rate. To overcome the issue that file popularity may be unknown or time-varying, we further provide an approximation of the heuristic pre-fetching policy which is irrelevant to the file popularity. We also discuss on the potential application of the proposed caching scheme in scenarios with heterogeneous file sizes. Numerical results show that the proposed scheme can substantially improve the backhaul utilization efficiency, and reduce the average file delivery time. The heuristic pre-fetching policy has similar performance with the optimal pre-fetching policy yet with much lower complexity.

Two-Stage Interference Cancellation for Device-to-Device Caching Networks.

Wireless device-to-device (D2D) caching networks are studied, in which n nodes are distributed uniformly at random over the network area. Each node caches M files from the library of size and independently requires a file from the library. Each request will be served by cooperative D2D transmission from other nodes having the requested file in their cache memories. In many practical sensor or Internet of things (IoT) networks, there may exist simple sensor or IoT devices that are not able to perform real-time rate and power control based on the reported channel quality information (CQI). Hence, it is assumed that each node transmits a file with a fixed rate and power so that an outage is inevitable. To improve the outage-based throughput, a cache-enabled interference cancellation (IC) technique is proposed for cooperative D2D file delivery which first performs IC, utilizing cached files at each node as side information, and then performs successive IC of strongly interfering files. Numerical simulations demonstrate that the proposed scheme significantly improves the overall throughput and, furthermore, such gain is universally achievable for various caching placement strategies such as random caching and probabilistic caching.

Recent evolutions in the LTDP CDF project

In the latest years, CNAF (the national center of the Italian Institute for Nuclear Physics INFN dedicated to Research and Development on Information and Communication Technologies) has been working on the Long Term Data Preservation (LTDP) project for the CDF experiment, active at Fermilab from 1990 to 2011. The main aims of the project are to protect the most relevant part of the CDF RUN-2 data collected between 2001 and 2011 and already stored on tape at CNAF (4 PB), as well as to ensure the availability and the access to the analysis facility to those data over time. Lately, the CDF database, hosting information about CDF datasets such as their structure, file locations and metadata, has been imported from Fermilab to CNAF. Also, the Sequential Access via Metadata (SAM) station data handling tool for CDF data management, that allows to manage data transfers and to retrieve information from the CDF database, has been properly installed and configured at CNAF. This was a fundamental step in the perspective of a complete decommissioning of CDF services on Fermilab side. An access system has been designed and tested to submit CDF analysis jobs, using CDF software distributed via CERN Virtual Machine File System (CVMFS) and requesting delivery of CDF files stored on CNAF tapes, as well as data present only on Fermilab storage archive. Moreover, the availability and the correctness of all CDF data stored on CNAF tapes has been verified. This paper describes all these recent evolutions in detail, presenting the future plans for the LTDP project at CNAF.

An Analysis on Wireless Edge Caching in In-Band Full-Duplex FR2-IAB Networks

This article develops a 3GPP inspired analytical framework for cache-enabled in-band full-duplex (IBFD) integrated access and backhaul (IAB) heterogeneous network in the FR2 (millimeter wave) band. In particular, by assuming wide-band FR2 channel model, we analyze the performance of cache-enabled IAB nodes that serve multiple users in access in IBFD mode through hybrid beamforming architectures. Since, IBFD transmission is considered, the IAB nodes are able to retrieve any non-cached files simultaneously through backhaul from the IAB donor nodes, which also use hybrid beamforming architectures. Utilizing stochastic geometry tools, we first derive the lower-bound for the average success probability (ASP) of file delivery for the considered system model, using which we evaluate two quintessential performance metrics: latency and average throughput of file delivery under a cache-enabled content delivery phase. Further, as a baseline for comparison, we also consider conventional half-duplex techniques, namely time division duplex and frequency division duplex transmission and evaluate their performance with respect to cache size, node density, content popularity, antenna numbers, blockage density, and residual self-interference. Numerical results demonstrate the precedency of using wireless edge caching as a cost-effective measure for improving the FR2-IAB network's performance. More importantly, we provide several design insights for the implementation of wireless edge caching in IBFD FR2-IAB networks, with respect to required residual self interference cancellation, increasing antenna number, increasing target data rate and IAB node density.

Delay and Power Tradeoff With Consideration of Caching Capabilities in Dense Wireless Networks

Enabling caching capabilities in dense small cell networks (DSCNs) has a direct impact on file delivery delay and power consumption. Most existing work studied these two performance metrics separately in cache-enabled DSCNs. However, file delivery delay and power consumption are coupled with each other and cannot be minimized simultaneously. In this paper, we investigate the optimal tradoff between these two performance metrics. Firstly, we formulate the joint file delivery delay and power consumption optimization (JDPO) problem where power control, user association and file placement are jointly considered. Then we convert it to a form that can be handled by Generalized Benders Decomposition (GDB). with GDB, we decompose the converted JDPO problem into two smaller problems, i.e., primal problem related to power control and master problem related to user association and file placement. An iterative algorithm is proposed and proved to be $\epsilon$-optimal, in which the primal problem and master problem are solved iteratively to approach the optimal solution. To further reduce the complexity of the master problem, an accelerated algorithm based on semi-definite relaxation is proposed. Finally, the simulation results demonstrate that the proposed algorithm can approach the optimal tradeoff between file delivery delay and power consumption.

Rate-Memory Trade-off for Multi-Access Coded Caching With Uncoded Placement

We study a multi-access variant of the popular coded caching framework, which consists of a central server with a catalog of $N$ files, $K$ caches with limited memory $M$, and $K$ users such that each user has access to $L$ consecutive caches with a cyclic wrap-around and requests one file from the central server's catalog. The server assists in file delivery by transmitting a message of size $R$ over a shared error-free link and the goal is to characterize the optimal rate-memory trade-off. This setup was studied previously by Hachem et al., where an achievable rate and an information-theoretic lower bound were derived. However, the multiplicative gap between them was shown to scale linearly with the access degree $L$ and thus order-optimality could not be established. A series of recent works have used a natural mapping of the coded caching problem to the well-known index coding problem to derive tighter characterizations of the optimal rate-memory trade-off under the additional assumption that the caches store uncoded content. We follow a similar strategy for the multi-access framework and provide new bounds for the optimal rate-memory trade-off $R^*(M)$ over all uncoded placement policies. In particular, we derive a new achievable rate for any $L \ge 1$ and a new lower bound, which works for any uncoded placement policy and $L \ge K/2$. We then establish that the (multiplicative) gap between the new achievable rate and the lower bound is at most $2$ independent of all parameters, thus establishing an order-optimal characterization of $R^*(M)$ for any $L\ge K/2$. This is a significant improvement over the previously known gap result, albeit under the restriction of uncoded placement policies. Finally, we also characterize $R^*(M)$ exactly for a few special cases.

Two Time-Scale Edge Caching and BS Association for Power-Delay Tradeoff in Multi-Cell Networks

More network operators have recently provided content delivery network (CDN) services, where traffic engineering techniques, such as the base station (BS) association, are jointly employed with content delivery. This deployment attempts to reduce the network operating cost and enhance the quality of service (QoS) of end users. Toward this end, we study the BS association and file caching problem considering the spatial diversity of the file popularity and the realistic time-scale separation between the file caching and the BS association decisions in this paper. Our design aims to minimize the file delivery latency and operating power consumption in the cellular networks, where the tradeoff between these conflicting objectives is controlled by a single parameter. The short time-scale BS association problem is solved by using the convex optimization technique for a given file caching solution. However, the long time-scale file caching problem considering the varying BS association decisions taken at the short time-scale is difficult to tackle. To solve this file caching problem, we prove and leverage the submodularity property of the underlying objective function to develop a greedy content caching algorithm that guarantees a constant approximation ratio of the optimal objective value. Via simulations using real-world datasets, we show that the proposed algorithms outperform file caching and BS association algorithms that do not consider the spatial diversity of the file popularity in terms of the power consumption and delay performance in the geographically heterogeneous file popularity scenario.

The Transfer Process from the Nasab Guardian to the Judge Guardian in the Case of Adhal Guardian through the Decision of 1B Class Religious Court of Batusangkar

Background related to case No. 0081/Pdt.P/2014/PA.Bsk was triggered by a problem where the assembly had tried to advise the applicant to approach and persuade the guardian of the applicant (the applicant’s father) to marry the applicant to the applicant’s future husband; however, it did not work. Meanwhile, the applicant stated that she still wanted to marry the applicant’s future husband. In addition, the assembly also advised the applicant’s father so that he would be willing to become the guardian of his daughter but the attempt was also unsuccessful. The reading of the applicant’s request stated that the applicant retained its the request contents. This study applies an empirical juridical approach which obtains data by referring to the juridical and empirical aspects as a tool. Based on the results of the study, the nasab guardian from the bride candidate did not want to marry his daughter to her future husband because of communication problems that were not built effectively. Thus, the nasab guardian assumed to refuse to marry his daughter to him because he did not participate in educating, caring for and raising this daughter. In determining the adhal guardian in case No. 0081/Pdt.P/2014/PA.Bsk, the consideration of the judge of the 1B Class Religious Court of Batusangkar was that the applicant’s guardian was present at the trial but he objected (reluctant) to become the applicant’s marriage guardian. In this case, the objection from the applicant’s guardian was groundless. Therefore, the assembly stipulated that the applicant’s guardian is adhal (reluctant). The marriage process carried out in Religious Court in the case of adhal guardian includes: 1) Delivery of files related to marriage data, 2) Marriage Registration Officer summons interested parties such as bride and groom, 3) Marriage Registration Officer records the marriage process, and 4) Implementation marriage contract.

Cache-Aided Non-Orthogonal Multiple Access: The Two-User Case

In this paper, we propose a cache-aided non-orthogonal multiple access (NOMA) scheme for spectrally efficient downlink transmission. The proposed scheme not only reaps the benefits associated with NOMA and caching, but also exploits the data cached at the users for interference cancellation. As a consequence, caching can help to reduce the residual interference power, making multiple decoding orders at the users feasible. The resulting flexibility in decoding can be exploited for improved NOMA detection. We characterize the achievable rate region of cache-aided NOMA and derive the Pareto optimal rate tuples forming the boundary of the rate region. Moreover, we optimize cache-aided NOMA for minimization of the time required for completing file delivery. The optimal decoding order and the optimal transmit power and rate allocation are derived as functions of the cache status, the file sizes, and the channel conditions. Simulation results confirm that, compared to several baseline schemes, the proposed cache-aided NOMA scheme significantly expands the achievable rate region and increases the sum rate for downlink transmission, which translates into substantially reduced file delivery times.

IMPLEMENTASI HYBRID LEARNING MENGGUNAKAN APLIKASI EDMODO PADA MATAKULIAH METODE PENELITIAN KUALITATIF

This article discusses the application of Hybrid Learning using the Edmodo application in the subject of the qualitative research method for fourth semester students at Podi PGMI UNISMA Malang. The discussion chapter is divided into three sub-topics. First is online lecture planning in qualitative research courses. Starting from semester learning plans, learning strategies and material preparation in the form of soft files, so that they are easily uploaded and downloaded by lecturers and students. The second is the implementation of online lectures in qualitative research courses. For some online college students it is new but for most online college students it is new. The difficulties and advantages of online ducting appear on each side. One of the difficulties associated with technical matters is understanding material and collecting tasks. From an excess point of view, one of them is that students no longer print assignments so they are more efficient because there are no printing costs for lecture assignments. The three Edmodo assessments provide a variety of assignment models ranging from file delivery assignments, choice of gandan, essay, match, and incorrect. In addition, the value of learning outcomes is better controlled because each task file, Edmodo provides an assessment form. So that students are able to know the assessment transparently. And if something goes wrong, students and lecturers can monitor each other while conducting joint evaluations.