The issue of guaranteeing Quality of Services (QoS) in a network has emerged in recent years. The Proportional Delay Differentiated Model has been presented to provide the predictable and controllable queueing delay differentiation for different classes of connections. However, most related works have focused on providing this model for a wired network. This study proposes a novel scheduler to provide proportional delay differentiation in a wireless network that includes a multi-state link. This scheduler, Look-ahead Waiting-Time Priority (LWTP), offers proportional delay differentiation and a low queueing delay, by adapting to the location-dependent capacity of the wireless link and solving the head-of-line (HOL) blocking problem. The simulation results demonstrate that the LWTP scheduler actually achieves delay ratios much closer to the target delay proportion between classes and yields smaller queueing delays than past schedulers.

A power and spreading gain allocation strategy is considered to effectively provide data services for mobile users with different levels of priorities in a DS-CDMA system. The priority level of a user is specified by a factor that is a weighting on the data throughput of the user. Our strategy implements a relative prioritization that affords a trade-off between spectral efficiency and strict prioritization.

This paper proposes a novel method of identifying the design parameters for a practical implementation of the fair queueing discipline, which is capable of class-level delay control. The notion of class weight is introduced at first, and then the session weights are determined. This two-phase approach is favorable in terms of the scalability;that is, the overall complexity is dependent upon the number of classes only. We propose a packet scheduler referred to as the DPS (Delay-centric Processor Sharing) scheme which employs those design parameters to deliver class-wise delay bound services. The associated admission policy for delay guarantee is also derived. System analysis and derivation of the parameters have their origins in the understanding of the so-called system equation, which describes the dynamics of the class-level service share. The proposed design parameters are QoS-aware in that they are consistently refined depending on the system status. Several numerical and simulation results show that the DPS scheme is advantageous over other ones in terms of both resource efficiency and the robustness. Concerning the scalability, we show that an alternative tagging process of the DPS scheme is implementable with O(1) complexity with no significant degradation in delay performance.

In this article we analyze the performance of a space division output buffered multichannel switch operating in an ATM multimedia environment as follows. Fixed size packets belonging to two classes arrive onto the switch inputs in each time slot. Class-1 packets, representing real time traffic such as live audio and live video communications, are sensitive to delay but insensitive to loss and have their own service time needs. Class-2 packets, representing nonreal time communications such as file transfers, are insensitive to delay but sensitive to loss and have their different service time needs. To respond to the class-1 delay sensitivity, the switch gives class-1 packets higher service priority over class-2. And to respond to the difference in service time needs, the switch operates at two service rates, one for each class. This latter assumption is the major feature of the article, as previous studies have usually assumed that the two classes have the same service needs and thus the same service rate. For the purpose of the analysis, the switch is modelled as a priority, discrete time, batch arrival, multiserver queueing system, with infinite buffer and two geometric service times with two parameters. Performance measures analyzed are system occupancy and packet waiting time.

Quality of Service (QoS) provisioning is a new but challenging research area in the field of Mobile Ad hoc Network (MANET) to support multimedia data communication. However, the existing QoS routing protocols in ad hoc network did not consider a major aspect of wireless environment, i.e., mutual interference. Interference between nodes belonging to two or more routes within the proximity of one another causes Route Coupling. This can be avoided by using zone-disjoint routes. Two routes are said to be zone disjoint if data communication over one path does not interfere with the data communication along the other path. In this paper, we have proposed a scheme for supporting priority-based QoS in MANET by classifying the traffic flows in the network into different priority classes and giving different treatment to the flows belonging to different classes during routing so that the high priority flows will achieve best possible throughput. Our objective is to reduce the effect of coupling between routes used by high and low priority traffic by reserving zone of communication. The part of the network, used for high priority data communication, i.e, high priority zone, will be avoided by low priority data through the selection of a different route that is maximally zone-disjoint with respect to high priority zones and which consequently allows contention-free transmission of high priority traffic. The suggested protocol in our paper selects shortest path for high priority traffic and diverse routes for low priority traffic that will minimally interfere with high priority flows, thus reducing the effect of coupling between high and low priority routes. This adaptive, priority-based routing protocol is implemented on Qualnet Simulator using directional antenna to prove the effectiveness of our proposal. The use of directional antenna in our protocol largely reduces the probability of radio interference between communicating hosts compared to omni-directional antenna and improves the overall utilization of the wireless medium in the context of ad hoc wireless network through Space Division Multiple Access (SDMA).

This letter reports on an approximation of the mean waiting time in a finite buffer queue with delay priority and loss priority. Both priorities are controlled by head-of-the-line (HOL) priority scheduling and buffer reservation. The proposed approximation is based on the known results on a HOL-priority queue with infinite buffer and a finite buffer queue with FIFO scheduling and buffer reservation. The accuracy of the approximation is validated by comparing exact and approximate results. The approximation provides good estimates when the blocking probabilities at the buffer controlled by the buffer reservation are low.

A special group of voice application services (VASs) are promising contents for wireless as well as wireline networks. Without a designated call admission policy, VAS calls are expected to suffer from relatively high probability of blocking since they normally require better signal quality than ordinary voice calls. In this letter, we consider a prioritized call admission design in order to reduce the blocking probability of VAS calls, which makes the users feel the newly-provided VAS in belief. The VAS calls are given a priority by reserving a number of channel-processing hardwares. With the reservation, the blocking probability of prioritized VAS calls can be evidently reduced. That of ordinary calls, however, is increasing instead. This letter provides a system model that counts the blocking probabilities of VAS and ordinary calls simultaneously, and numerically examines an adequate level of the prioritization for VAS calls.

This paper proposes a real-time scheduling mechanism for web server that finds a way to solve so-called priority inversion problem between tasks handling real-time web requests with higher priorities and tasks with lower priorities like HTML requests. The priority inversion problem of web server stems from operating two independent schedulers, web scheduler and kernel scheduler, without exchanging scheduling information or considering the requirement of each other. In the proposed mechanism, two schedulers are integrated in a kernel and the integrated scheduler schedules real-time web tasks and other application tasks together based on their priorities. Since the unified scheduler sees all tasks simultaneously in system, it can schedule the tasks with their absolute priorities and reduce the execution delay caused by the priority inversion. The proposed mechanism provides web server with a better chance to efficiently serve real-time web requests. The feasibility and performance of the proposed mechanism are empirically shown on an embedded system.

CPCH is an uplink common channel that is used by 3GPP to support reliable packet transport. In this paper, we propose a new access scheme by using the discrimination of backoff timer for providing a prioritized service. We also present a simple system model of CPCH for EPA and use it to derive mathematical results. The results show that multi-class services with different priorities can be served effectively and easily by the proposed scheme.

In IP networks, QoS guarantee is becoming important, to allow real-time services such as voice over IP (VoIP) and video conferencing. To guarantee various QoS requirements from a variety of applications, call admission control (CAC) together with a service differentiation mechanism is useful. Service differentiation enables the network to provide different QoSs to various applications, by assigning priority classes to calls. Then, CAC limits the acceptance of new calls to prevent the QoSs of established calls from degrading. For this environment, we propose a CAC method in which priority classes assigned to already established calls are changed adaptively. Classes may be modified when the CAC function handles the acceptance of a new call if that can decrease the blocking probability. The effect of the method is shown by numerical examples.

In this paper, we propose a novel 2D plenoptic function called "acentric panorama view (APV)." This novel 2D plenoptic function samples the panorama scenes without oversampling or undersampling. A single APV can be accelerated by view culling and list-priority rendering algorithm. Multiple APVs with special fields of view, 45, 60, 90, and 120, can be integrated into a larger configuration called augmented APVs, which can augment the walking area in a planar walkthrough environment to form a 4D plenoptic function. In augmented APVs, the acceleration schemes of a single APV can still be applied successfully.

In this paper, we propose a packet-scheduling algorithm, called the Class-level Service Lagging (CSL) algorithm, that guarantees multiple delay bounds for multi-class traffic in packet networks. We derive the associated schedulability test conditions, which are used to determine call admission. We first introduce a novel implementation of priority control, which has a conventional and simple form. We show how the efforts to confirm the logical validity of that implementation are managed to reach the definition of the CSL algorithm. The priority control is realized by imposing class-level unfairness in service provisioning, while the underlying service mechanism is carried out using the notion of fair queueing. The adoption of fair queueing allows the capability to maintain the service quality of the well-behaving traffic even in the presence of misbehaving traffic. We call this the firewall property. Simulation results demonstrate the superiority of the CSL algorithm in both priority control and firewall functionality. We also describe how the CSL algorithm is implementable with a computational complexity of O(1). Those features as well as the enhanced scalability, which results from the class-level approach, confirm the adequacy of the CSL algorithm for the fast packet networks.

In this paper, we propose a new job scheduling method for distributed parallel systems that can simultaneously achieve two main goals of the job scheduling in those systems: to minimize the execution time of a parallel job without disturbing the execution of the other jobs. We try to achieve those goals by introducing a new scheduler, called active scheduler, that dynamically controls the priority of parallel programs and balances the workload of host computers depending on the status of the underlying runtime environment. We implemented a prototype system of the scheduler to evaluate its effectiveness. The result of experiments implies that the overhead of introducing the active scheduler is at most 15% of the original execution time, and it is in fact effective to adjust the execution of parallel programs to an actual distributed environment in which many users execute their jobs simultaneously.

We developed a priority queueing method that can keep the loss ratio of high-priority packets at a target value. It regulates the number of input low-priority packets when the queue length exceeds the threshold that is adjusted so as to minimize the Lyapunov function of the system. We showed that the number of calculations for the optimum threshold is sufficiently small and derived a sufficient condition for the proposed method to be robust against unknown load fluctuations. From the viewpoint of guaranteeing the loss ratio of high-priority packets, we showed, by computer simulation and theoretical analysis, that the proposed method is superior to conventional methods such as the fixed-threshold method and the pushout method.

In this paper, we show that a priori probabilities of information bits can be incorporated into metrics for syndrome decoding. Then it is confirmed that soft-in/soft-out decoding is also possible for syndrome decoding in the same way as for Viterbi decoding. The derived results again show that the two decoding algorithms are dual to each other.

In this paper, we analyze the performance of a bulk handoff scheme for mixed traffic in integrated voice/data wireless mobile networks in which new and handoff voice/data calls are accepted based on prioritization of handoff requests. If fewer channels than handoff calls are available in the target cell, some handoff calls are terminated without queuing. A higher priority is given to voice handoff calls than to data handoff calls. A multidimensional birth-death process model is presented to analyze the bulk handoff performance of mixed traffic. A numerical analysis of system performance is presented to evaluate the blocking probabilities of new voice and data calls, handoff failure probabilities, and the forced termination probabilities of voice/data handoff calls.

This paper deals with two-processor nonpreemptive scheduling problem for acyclic SWITCH-less program nets including two types of nodes: AND-node and OR-node. Compared with task graphs that are a special case of acyclic SWITCH-less program nets and include only AND-nodes, the multiprocessor scheduling problem of general acyclic SWITCH-less program nets is more complicated. Since multiprocessor scheduling problem for general task graphs is NP-hard, so is for acyclic SWITCH-less program nets generally. In this paper, we suppose the acyclic SWITCH-less program nets satisfy: (i) each AND-node and OR-node have 1 and 0 node firing time, respectively; (ii) each AND-node possesses single input edge. For such a class of acyclic SWITCH-less program nets, we first propose a hybrid priority list L that consists of both dynamic and static sub-lists. Then we prove that, for a given acyclic SWITCH-less program net to be executed by two identical processors, the schedule generated by L is optimal.

In this paper, we propose an algorithm to calculate the higher moments of the busy period length of a discrete-time M/G/1 type queue with finite buffer. The queueing model has a level-dependent transition probability matrix. Our algorithm is given as a set of recursive formulas which are derived from the relationship among the generating function matrices of the fundamental period. As an example of our algorithm, we provide an approximate analysis of a HOL (Head Of Line) priority control queue.

Under cutoff and threshold priority policies, we mathematically formulate a prioritized channel allocation problem which is combinatorial in nature. We then reduce that problem using the concept of pattern, and apply a simulated annealing approach to the reduced problem. Computational experiments show that our method works very well and the cutoff priority policy outperforms the non-prioritized complete sharing policy and the threshold priority policy.

There exist some results showing that quantum communications are more powerful than classical communications. Moreover, although quantum entangled states do not give extra information, by using prior entanglement the quantum communication complexity of some functions is less than the classical communication complexity. The communications with prior entanglement can be regarded as a type of public coin models. In this paper, we investigate quantum communications for multi-party with prior entanglement, and show that there exists a generalized inner product function for k-party such that the quantum communication complexity is at most k bits, but the classical communication complexity needs at least 3k/2 bits. Moreover, we also provide a generalized form of prior entanglements that is effective in order to compute some type of Boolean functions.