5,820 research outputs found
PSA: The Packet Scheduling Algorithm for Wireless Sensor Networks
The main cause of wasted energy consumption in wireless sensor networks is
packet collision. The packet scheduling algorithm is therefore introduced to
solve this problem. Some packet scheduling algorithms can also influence and
delay the data transmitting in the real-time wireless sensor networks. This
paper presents the packet scheduling algorithm (PSA) in order to reduce the
packet congestion in MAC layer leading to reduce the overall of packet
collision in the system The PSA is compared with the simple CSMA/CA and other
approaches using network topology benchmarks in mathematical method. The
performances of our PSA are better than the standard (CSMA/CA). The PSA
produces better throughput than other algorithms. On other hand, the average
delay of PSA is higher than previous works. However, the PSA utilizes the
channel better than all algorithms
Multi-View Video Packet Scheduling
In multiview applications, multiple cameras acquire the same scene from
different viewpoints and generally produce correlated video streams. This
results in large amounts of highly redundant data. In order to save resources,
it is critical to handle properly this correlation during encoding and
transmission of the multiview data. In this work, we propose a
correlation-aware packet scheduling algorithm for multi-camera networks, where
information from all cameras are transmitted over a bottleneck channel to
clients that reconstruct the multiview images. The scheduling algorithm relies
on a new rate-distortion model that captures the importance of each view in the
scene reconstruction. We propose a problem formulation for the optimization of
the packet scheduling policies, which adapt to variations in the scene content.
Then, we design a low complexity scheduling algorithm based on a trellis search
that selects the subset of candidate packets to be transmitted towards
effective multiview reconstruction at clients. Extensive simulation results
confirm the gain of our scheduling algorithm when inter-source correlation
information is used in the scheduler, compared to scheduling policies with no
information about the correlation or non-adaptive scheduling policies. We
finally show that increasing the optimization horizon in the packet scheduling
algorithm improves the transmission performance, especially in scenarios where
the level of correlation rapidly varies with time
Packet scheduling under imperfect channel conditions in Long Term Evolution (LTE)
University of Technology, Sydney. Faculty of Engineering and Information Technology.The growing demand for high speed wireless data services, such as Voice Over Internet Protocol (VoIP), web browsing, video streaming and gaming, with constraints on system capacity and delay requirements, poses new challenges in future mobile cellular systems. Orthogonal Frequency Division Multiple Access (OFDMA) is the preferred access technology for downlink Long Term Evolution (LTE) standardisation as a solution to the challenges. As a network based on an all-IP packet switched architecture, LTE employs packet scheduling to satisfy Quality of Service (QoS) requirements. Therefore, efficient design of packet scheduling becomes a fundamental issue. The aim of this thesis is to propose a novel packet scheduling algorithm to improve system performance for practical downlink LTE system.
This thesis first focuses on time domain packet scheduling algorithms. A number of time domain packet scheduling algorithms are studied and some well-known time domain packet scheduling algorithms are compared in downlink LTE. A packet scheduling algorithm is identified that it is able to provide a better trade-off between maximizing the system performance and guaranteeing the fairness.
Thereafter, some frequency domain packet schemes are introduced and examples of QoS aware packet scheduling algorithms employing these schemes are presented. To balance the scheduling performance and computational complexity and be tolerant to the time-varying wireless channel, a novel scheduling scheme and a packet scheduling algorithm are proposed. Simulation results show this proposed algorithm achieves an overall reasonable system performance.
Packet scheduling is further studied in a practical channel condition environment which assumes imperfect Channel Quality Information (CQI). To alleviate the performance degradation due to simultaneous multiple imperfect channel conditions, a packet scheduling algorithm based on channel prediction and the proposed scheduling scheme is developed in downlink LTE system for GBR services. It was shown in simulation results that the Kalman filter based channel predictor can effectively recover the correct CQI from erroneous channel quality feedback, therefore, the system performance is significantly improved
Dynamic Packet Scheduling in Wireless Networks
We consider protocols that serve communication requests arising over time in
a wireless network that is subject to interference. Unlike previous approaches,
we take the geometry of the network and power control into account, both
allowing to increase the network's performance significantly. We introduce a
stochastic and an adversarial model to bound the packet injection. Although
taken as the primary motivation, this approach is not only suitable for models
based on the signal-to-interference-plus-noise ratio (SINR). It also covers
virtually all other common interference models, for example the multiple-access
channel, the radio-network model, the protocol model, and distance-2 matching.
Packet-routing networks allowing each edge or each node to transmit or receive
one packet at a time can be modeled as well.
Starting from algorithms for the respective scheduling problem with static
transmission requests, we build distributed stable protocols. This is more
involved than in previous, similar approaches because the algorithms we
consider do not necessarily scale linearly when scaling the input instance. We
can guarantee a throughput that is as large as the one of the original static
algorithm. In particular, for SINR models the competitive ratios of the
protocol in comparison to optimal ones in the respective model are between
constant and O(log^2 m) for a network of size m.Comment: 23 page
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