IEEE 802.15.4e network aims at providing highly reliable communication links via time slotted channel hopping (TSCH) technology for lossy wireless channels. In such network, all nodes remain synchronized via message exchange periodically to compensate for the clock drift. In this paper, we derive theoretical average time for a node to remain in synchronized status with its parent node under the noisy channel scenario. Carried-out simulation results verify the correctness of our derived theoretical results.

The Ethernet passive optical network (EPON) is one of the most efficient transmission technologies for broadband access. However, an unregulated transmission could waste energy if an ONU transmits an insufficient or excessive amount of packets in one time cycle on an energy saving EPON network. For an insufficient transmission, it invokes an unnecessary power consumption, since a power saving ONU has to wake up early for transmitting few packets only. For an excessive transmission, it allows an ONU to stay at the active mode for a longer time but to push other ONUs out of transmission cycle. Load regulation enables an energy saving EPON system to provide near constant loading. This paper studies an appropriate threshold for an ONU to switch between active or energy saving modes. Performance results reveal that satisfactory power saving effects can be achieved via proper load regulation applied on both upstream and downstream channels at the cost of the delay performances of low-priority packets.

WiMAX features several QoS service classes to schedule different types of traffic. In this paper, we will assess the existence of self-similar traffic for each service class. The experiment starts by capturing the traffic data with a dedicated SNMP-based network management system (NMS). NMS manages the deployment of fixed WiMAX network defined in IEEE 802.16d-2004 Standard and records the inbound and outbound traffic for specific object IDs (OIDs). We consider several criteria to generate the traffic for our WiMAX test-bed network such as QoS service class, traffic intensity, and application type. The recorded traffic then will be analyzed using variance plot, and RS-plot. The result shows various degree of self-similarity for different types of QoS service classes and traffic intensities.

This paper studies the admission control and resource allocation in a cell-based wireless system that supports single- media and multirate services. Utilizing the idea of adaptive and dynamic reallocation, we propose three control policies, AO, ADRF, and ADRA. The Markov decision process (MDP) theory is used to build the model of the system. We solve the MDP model and find the optimal policy by linear programming (LP). The proposed policies not only make the best use of precious wireless bandwidth, but also satisfy the requirement of quality of services such as handover blocking probability.

The research works on the mobile ad hoc networks (MANET) have attracted wide attentions over the past few years. In order to evaluate and verify the underlying protocols or applications, researchers run simulations to generate results. By controlling different simulation parameters, we can run our programs in diverse simulation scenarios. Mobility model of mobile nodes in MANET plays an important role in simulations but its importance is often ignored. Random waypoint (RWP) is one of the most deployed mobility models in papers. RWP has the properties that are understandable and quick to implement. Until recently, several defects in RWP is unknown. One is decaying average speed and another is border effect. Besides the problems in RWP, there is still a missing property in many mobility models. Diverse average speed (DAS) is a more realistic requirement for mobility models. Most mobility models only can generate one average speed scenario with the same speed range. It is reasonable to provide different average speed within the same speed range. We propose general ripple mobility model (GRMM) of speed-time pairing to provide a similar mobility model to RWP without the defects of RWP. GRMM also provides DAS to generate different mobility scenarios. The simulation results show that GRMM of speed-time pairing can generate the mobility pattern of uniform spatial distribution and diverse average speed.

This paper studies the radio resource allocation for GPRS (general packet radio service) downlink traffic supporting two class of mobile terminals with different bandwidth requirements. We proposed a complete time-slot partitioning and complete radio-block sharing scheme. The allocation strategy can not only characterize the practical multiplexing scheme but also provide high performance. By both theoretical analysis and computer simulation, the result showed that the proposed resource allocation strategy offers high utilization as well as low blocking probability to users under various traffic conditions.

The paper focuses on the issues of admission control and rerouting for LEO satellite networks providing multimedia services. The issues includes resource allocation and routing for intersatellite links (ISLs), load balance amongst links, and satellite handover and rerouting caused by satellites' dynamic characteristics. Applying Markov decision process (MDP) theory and generic policy-iteration formulation, a distributed routing scheme, called adaptive cost routing (ACR), is proposed. Comparing the performance of ACR with other routing schemes in terms of system throughput and blocking rate, the ACR presents not only a better routing performance, but also less connection setup time. It is also easier to implement than most centralized routing algorithms.

In this paper, we first propose and compare various multicast scheduling protocols for an asynchronous WDM optical star network. A central traffic scheduler is allocated to coordinate message transmissions. The proposed scheduling schemes can be executed in real time and are conducted in two phases. The first phase is to search (through input queues) for a candidate multicast message that can be sent, without partition, to all of its intended recipients. The second phase efficiently partitions a multicast message into multiple transmissions, when phase 1 fails. Such an approach significantly improves channel and receiver utilization levels, thus effectively reducing the performance degradation caused by head-of-line blocking effects. To apply these mechanisms to a wider range of networking environments, we further consider an interconnected dual-star architecture and propose associated algorithms. By using a simple heuristic approach, these schemes are able to successfully exploit the inter data channels and properly utilize the wavelength reuse property of the intra data channels. Performance results have shown the merits of deploying the multicast algorithms in such an interconnected structure.

The main motivation for developing the MetaRing architecture was to increase the throughput of a ring-based local area network beyond its single link capacity by means of spatial bandwidth reuse. We describe and evaluate a protocol for integrating two types of traffic on the MetaRing architecture. Synchronous (reserved or real-time) traffic which is periodic and requires a connection set-up and will have guaranteed bandwidth and bounded delay, and asynchronous or bursty traffic with no real-time constraints that can use the remainder of the bandwidth in a fair manner. The integration mechanism is functionally equivalent to the timed-token function in FDDI, which is a shared media ring protocol. Simulation results are also presented to show the effects of the fairness and flow control signals on the performance of the network.

A full-duplex ring network combined with destination removal can achieve a network throughput level much higher than the channel's data rate. However, such a network exhibits fairness problems, particularly under asymmetric-loading conditions. We propose and study a local regulation protocol, the check-quota-before-transmission (CQBT) algorithm, to effectively reduce the unfairness features associated with such a network. Under this algorithm, each heavily loaded node monitors its local traffic conditions to determine the access opportunities provided to its downstream neighboring nodes. A procedure to determine the value of the regulation parameters associated with such an algorithm is also presented. Illustrative performance examples are shown to demonstrate the effectiveness of this algorithm. In addition, through the use of analytical approximations, we present a discrete time vector Markov chain model to analyze the queueing behavior of such a full-duplex slotted ring. The analytical performance results are shown to be close to those obtained by simulations.

The authors propose and study a protocol for asynchronous transfer mode (ATM) networks, called the fair and efficient cyclic control algorithm (FECCA), which combines the advantages of both global and local fairness schemes, to achieve a fair access mechanism while yielding high network throughput levels for a full-duplex ring network with spatial reuse. In addition, through the use of queuing models and analytical approximations, they present an analytical method for evaluating the network throughput performance for a special network topology. The analytical performance results are shown to be close to those obtained by simulations.>