Jaiyong Lee

M2M Service Platforms: Survey, Issues, and Enabling Technologies

Machine-to-Machine (M2M) refers to technologies with various applications. In order to provide the vision and goals of M2M, an M2M ecosystem with a service platform must be established by the key players in industrial domains so as to substantially reduce development costs and improve time to market of M2M devices and services. The service platform must be supported by M2M enabling technologies and standardization. In this paper, we present a survey of existing M2M service platforms and explore the various research issues and challenges involved in enabling an M2M service platform. We first classify M2M nodes according to their characteristics and required functions, and we then highlight the features of M2M traffic. With these in mind, we discuss the necessity of M2M platforms. By comparing and analyzing the existing approaches and solutions of M2M platforms, we identify the requirements and functionalities of the ideal M2M service platform. Based on these, we propose an M2M service platform (M2SP) architecture and its functionalities, and present the M2M ecosystem with this platform. Different application scenarios are given to illustrate the interaction between the components of the proposed platform. In addition, we discuss the issues and challenges of enabling technologies and standardization activities, and outline future research directions for the M2M network.

Performance Evaluation of Synchronous and Asynchronous MAC Protocols for Wireless Sensor Networks

In the wireless sensor networks (WSNs), Synchronous approaches share the schedule information that specifies the cycle of active and sleep period by the control packets. On the other hand, asynchronous approaches do not exchange the synchronization information to send or receive data. Instead, they employ preamble sampling to do that. In this paper, we compare and analyze synchronous and asynchronous MAC protocols for WSNs with our two proposed schemes (AD-MAC and AS-MAC). Our proposed schemes present an enhanced adaptive duty cycling and high low power listening algorithm for energy efficiency, respectively.The performance of those two MAC mechanisms with our proposed protocols will be investigated through simulation and analysis to design the effective MAC protocol in WSNs.

A well-defined Estelle specification for the automatic test generation

The characteristics of the Estelle specification language are analyzed and a well-defined specification, a restricted form of an Estelle specification, is proposed based on the analyzed results to enable a direct derivation of a single reduced finite state machine-which is called a CFG (control flow graph)-from the specification written in Estelle. The derived CFG provides a basis for the automatic test case generation. Algorithms to test whether the specification written in Estelle is well defined or not, and to generate the CFG from the well-defined specification, are developed. Finally, as an example, the proposed technique is applied to TP0 (transport protocol class 0) specification written in Estelle. In applying these algorithms to the Estelle specification, some guidelines are also suggested for the specification which is not well defined. >

IEEE 802.15.4 Based QoS Support Slotted CSMA/CA MAC for Wireless Sensor Networks

In wireless sensor network, IEEE 802.15.4 should operate in beacon-enabled mode in order to schedule periodic sleep and wake up to minimize energy consumption. In beacon enabled mode QoS is supported by using guaranteed time slots(GTS). However maximum number of GTS node cannot exceed seven, and the number is not sufficient for wireless sensor network which have high node density. In this paper, we present QoS support mechanism in beacon enabled mode using CSMA/CA back-off time. Our algorithm have compatibility with IEEE 802.15.4 Standard, which means that there is no need to change hardware to support QoS on existing network. We will analysis the performance of our algorithm to design QoS parameters.

Scalable MPLS multicast using label aggregation in Internet broadcasting systems

In previous years, the Internet using a conventional IP mechanism had a lot of problems such as slow packet forwarding, complex routing and inefficient usage of network resources. Multi-Protocol Label Switching (MPLS) is one of the mechanisms that are proposed to solve these problems. In addition, multicast is one of the big issues in the Internet society because it can efficiently support real-time multimedia traffic. Therefore, the next generation Internet will be a system which have an MPLS backbone and can support multicast. An MPLS multicast mechanism is considered under Internet broadcasting systems. Specially, the scalability problem of common problems in MPLS and multicast is solved using label aggregation. In the proposed algorithm, the Label Edge Router (LER) of edge router in MPLS has a new table containing information of each tree node. The table is called the multicast Tree Node Table. Extending the Constraint-based Routed Label Distribution Protocol (CR-LDP), the label allocation is performed by using this table. The scalability problem can be solved using this algorithm because it reduces label consumption. So, the MPLS multicast mechanism can be easily supported in a large Internet backbone network.

Test selection for a nondeterministic FSM

In testing Nondeterministic Finite State Machines (NFSMs), testing process becomes hypothesis testing, if test sequence repetition numbers are not large enough to satisfy the so-called complete-testing assumption. In this paper, we present a method to determine the repetition numbers of test sequences assuming that each transition is executed with a fixed probability when nondeterministic choice is made. The proposed method ensures the test pass probability of restricted class of faulty machines to be never greater than a given value. Also, we discuss how to select a test suite for NFSMs that guarantees the minimal total test length.

Lost retransmission detection for TCP SACK

There have been a lot of works to avoid retransmission timeout (RTO) of transmission control protocol (TCP) that takes place in an unnecessary situation. However, most current TCP implementations, even if selective acknowledgment (SACK) option is used, do not have a mechanism to detect a lost retransmission and avoid subsequent RTO. In this letter, we propose a simple modification that enables a TCP sender using SACK option to detect a lost retransmission, which is called TCP SACK+ in simple. We use a stochastic model to evaluate the performance of TCP SACK+. Numerical results evaluated by simulations show that TCP SACK+ improves the loss recovery of TCP SACK significantly in presence of random losses.

Network management framework and lifetime evaluation method for wireless sensor networks

Network Management is the process of managing, monitoring, and controlling the network. Conventional network management was based on wired network which is heavy and unsuitable for resource constrained Wireless Sensor Networks WSNs. WSNs can be large scale networks and it is impossible to manage each node individually. Also, the polling mechanism of Simple Network Management Protocol SNMP imposes heavy management traffic overhead. Since management messages consume resources of WSNs, it can affect the performance of the network. Therefore, it is necessary for WSNs to perform energy efficient network management. Moreover, the management of WSNs should support sustainability. In this paper, we propose a network management framework for WSNs to reduce management traffic. Based on the cluster-based network management architecture, we classify the Management Information Base MIB and define the management messages and message exchange operation for each kind of MIB. The analysis result indicates that the proposed framework can reduce management traffic compared to the polling mechanism and there exists an optimal number of clusters for a given number of nodes. We also propose a lifetime estimation method as an application of the proposed framework. The proposed method uses messages of the proposed framework and estimate the network lifetime from the received management information. Simulation result shows that the proposed method can evaluate the network lifetime and reduce the number exchanged message by using the cluster-based architecture.

A performance model for admission control in IEEE 802.16

For systems based on connection-oriented services, such as IEEE 802.16, call admission control (CAC) strategy is essential to provide a desired level of quality of service (QoS). Although many handoff-prioritized CAC schemes, which assume a fixed channel capacity, have been introduced, this assumption is not always valid for IEEE 802.16 that uses adaptive modulation and coding (AMC). With AMC, the modulation type of a user’s connection can be changed dynamically and the ongoing connection might fail due to the change of modulation. In this paper, we approach the AMC-induced CAC problem by focusing on the guaranteed connection. Three kinds of calls, new, handoff, and modulation-changed calls, are considered. We propose a modified guard channel CAC scheme that allows the modulation-changed and handoff calls to use the guard channel. Then we analyze a Markov model for the CAC scheme with long-term AMC in mind. According to the simulation results, the proposed approach reduces the call dropping probability for modulation-changed calls, which suggests the threshold of guard channels in IEEE 802.16 can be determined based on the proposed approach.

Comparison of symmetric and asymmetric routing for fixed two-hop cellular relaying network

In this paper, routing strategies for fixed two-hop cellular relaying networks are discussed in terms of area spectral efficiency. We consider symmetric and asymmetric routing in uplink and downlink. Simulation results show that relaying increases the average throughput in comparison with conventional cellular networks and the area spectral efficiency of asymmetric routing is slightly better than that of the symmetric