A QoS-aware cross-layer scheduling scheme for multiuser mixed-traffic cognitive radio networks
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Abstract:
The emerging technology of cognitive radio (CR) allows secondary users (SUs) to gain access to radio spectrum which is licensed to but temporarily unoccupied by primary users (PUs). Apart from spectrum sensing, dynamic spectrum access (DSA) is an important processing task for CR networks (CRNs). Its aim is to allocate spectrum for SUs dynamically without causing any harm to PUs. CRNs may support different traffic types that may have different quality of service (QoS) requirements. In order to meet these QoS requirements, channel states, queue states and traffic types should be taken into account in designing DSA schemes. However, traffic types handled by SUs are treated equally in most existing DSA schemes. We propose a cross-layer scheduling scheme by incorporating DSA, packet scheduling and a channel sharing policy to achieve efficient QoS support for SUs with different traffic types. QoS performance of the proposed scheduling scheme is evaluated in terms of average throughput, average packet delay and packet dropping probability for SUs with different traffic types. Simulation results show that the proposed scheduling scheme outperforms the conventional scheduling scheme by providing more efficient QoS support for SUs and higher throughput fairness among SUs as the PU's activity factor increases.Keywords:
Traffic classification
Maximum throughput scheduling
Network coding techniques are usually applied upon network-layer protocols to improve throughput in wireless networks. In scenarios with multiple unicast sessions, fairness is also an important factor. Therefore, a network coding-aware packet-scheduling algorithm is required. A packet-scheduling algorithm determines which packet to send next from a node’s packet backlog. Existing protocols mostly employ a basic round-robin scheduling algorithm to give “equal” opportunities to different packet flows. In fact, this “equal”-opportunity scheduling is neither fair, nor efficient. This paper intends to accentuate the importance of a coding-aware scheduling scheme. With a good scheduling scheme, we can gain more control over the per-flow throughput and fairness. Specifically, we first formulate a static scheduling problem and propose an algorithm to find the optimal scheduling scheme. We then extend the technique to a dynamic setting and, later, to practical routing protocols. Results show that the algorithm is comparatively scalable, and it can improve the throughput gain when the network is not severely saturated. The fairness among flows is drastically improved as a result of this scheduling scheme.
Maximum throughput scheduling
Fair queuing
Linear network coding
Fairness measure
Proportionally fair
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Maximum throughput scheduling
Proportionally fair
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Scheduling allots the frequency and time resources of the LTE network to the users based on certain algorithms. The aim of an efficient fair scheduling is to provide the radio resources such that all the users are serviced almost equally over time without reducing the average user throughput. In this paper a fair scheduling algorithm named Blind Equal Throughput is modified and tested in different user conditions and a new scheduling scheme named Proportional Equal Throughput (PET) is developed which offers better fairness among users without reducing average user throughput, in comparison with other scheduling algorithms.
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Proportionally fair
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This paper considers the problem of uplink scheduling in wireless networks supporting successive interference cancellation (SIC) at the physical layer. By allowing concurrent interfering transmissions, SIC enables multi-packet reception at the receiver resulting in increased network throughput. Specifically, we consider maximum throughput scheduling and proportional fair scheduling problems and study optimal and heuristic algorithms for these problems. We prove that the maximum throughput scheduling problem is NP-hard and develop a throughput efficient polynomial time greedy algorithm for the problem. While being throughput efficient, the maximum throughput scheduling can lead to highly unfair rates among the users. The proportional fair scheduling, on the other hand, is not throughput optimal but achieves proportional fairness among the users. For scheduling multiple users in a single time-slot, we show that there exists an algorithm that solves the proportional fair scheduling problem in polynomial time. For scheduling in multiple time-slots, we develop a greedy algorithm that computes a highly fair schedule in polynomial time. Numerical results are also provided to show the utility and efficiency of the proposed scheduling algorithms in various simulated networks.
Maximum throughput scheduling
Proportionally fair
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Lottery scheduling
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These days, the problems of scheduling and security are increasingly pressing as a result of the rapidly growing number of implementations that are operated in operating systems. Process scheduling and scheduling security is the most effective methodology of operating a system which can improve and degrade the performance of the computer system. The performance of scheduling algorithm in operating system can be measured by scheduling principles like average waiting time, average turnaround time, response time, throughput etc. Much research carried out over operating system security and round robin scheduling used in time sharing operating system in previous years to resolve the issues regarding to improvement in the performance of round robin (RR) scheduling and improving the security in the scheduling approach. This study discussed the security issues in operating systems, scheduling security and discrete structure of a new approach for RR scheduling. The researcher has suggested a list of policy for scheduling method security and proposed a new approach for RR scheduling and investigated the scheduling principles. The proposed methodology covers distinctive strategy for selection manner of process from ready queue than RR and used diverges time quantum. The proposed methodology has been validated experimentally by comparing with a numerous scheduling algorithm namely as Round Robin (RR), Adaptive Round Robin (ARR), Round Robin Remaining time (RRRT), improved Round Robin (IRR), an additional improvement on the improved Round Robin (AAAIRR), and an Enhanced Round Robin (ERR). Numerous simulations have been conducted to validate the effectiveness of the proposed algorithm to compelling the performance of system. At the conclusion the performance of computing system is dependent on security of operating system as well as secluding methods.
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Turnaround time
Lottery scheduling
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In this paper, a packet scheduling algorithm called distributed elastic round robin (DERR) suitable for operation in a distributed environment is proposed to provide fair scheduling for the IEEE 802.11 wireless LAN. By simulations, we show that DERR possesses slightly improved performance in throughput and delay and exhibits better fairness than distributed deficit round robin (DDRR), which is a previously proposed fair scheduling algorithm in the literature.
Maximum throughput scheduling
Weighted round robin
Proportionally fair
Fair queuing
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In this paper classic static and dynamic scheduling strategy is analyzed first, and then communication network of schedule ability judgment basis is given. An improved dynamic EDF scheduling algorithm is proposed in order to improve the scheduling task of real-time. The scheduling strategy is to change task priority according to the transmission error over deadline task when applying dynamic EDF scheduling strategy. True Time tool is used to build CAN network control system simulation platform. Dynamic EDF scheduling algorithm and improved scheduling algorithm are simulated respectively. The effectiveness of improved scheduling algorithm is verified by the simulation Keywords-Network control system; Scheduling Algorithm; True Time toolbox result.
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Toolbox
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