An Enhanced Cross-Layer Two-Stage Scheduler for Wireless LANs

Könsgen, Andreas; Herdt, W.; Wang, Hongyou; Timm‐Giel, Andreas; Görg, Carmelita

doi:10.1109/pimrc.2007.4394577

Cited by 6 publications

(4 citation statements)

References 8 publications

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“…However, they have directed their attention to the IEEE 802.11 distributed channel access (DCA) function striving to determine both the optimal packet size and the optimal minimum contention window under various traffic loads and channel conditions. Unlike these single-layer based approaches, Könsgen et al [12] have exploited crosslayer optimization to improve the throughput of quality of service (QoS) traffic. Their main focus is the physical and Medium Access Control (MAC) layers.…”

Section: Related Workmentioning

confidence: 99%

Optimized packet formation in multi‐level security wireless data acquisition networks

Younis¹,

Farrag²,

Lee³

et al. 2010

Security Comm Networks

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The limited channel capacity and the varying propagation conditions of radio signals have motivated research for boosting the achievable throughput in wireless networks. Among the effective optimization strategies is to dynamically adjust the packet size either to better suit the channel conditions or to minimize the number of overhead bits in the individual packets. However, multi-levels of security requirements impose constraints on the data mix in the packet payload and may diminish the gains achievable by contemporary packet-size optimization schemes. This paper presents a novel bandwidth optimization algorithm for wireless data acquisition networks where strict confidentiality requirements and access restriction policies have to be observed. The algorithm exploits the classification of data in minimizing the number of packet transmissions as well as the overhead within the individual packets. The idea is to combine the transmission of packets based on the time sensitivity and security attributes of the data in the payload. The performance of the proposed algorithm is validated through mathematical analysis and through simulation. The simulation results confirm the effectiveness of the algorithm in boosting data throughput in the network.

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Section: Related Workmentioning

confidence: 99%

Optimized packet formation in multi‐level security wireless data acquisition networks

Younis¹,

Farrag²,

Lee³

et al. 2010

Security Comm Networks

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“…The general concept of the system was introduced in [1] and extended by QoS support in [2]. In each turn of the scheduling process, the MAC scheduler assigns a priority to the data packet at the top of each queue according to throughput and delay requirements of the application.…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis of Packet Aggregation in WLANs with Simultaneous Multi-user Access

Könsgen

Islam

Timm‐Giel

et al. 2009

Lecture Notes in Computer Science

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Abstract.A cross-layer wireless LAN system is considered which transmits packets for a number of users simultaneously using OFDMA or SDMA transmission. Due to varying packet lengths and physical bitrates for each user, this results in different transmission times so that users with faster transmissions have to wait until the transmission of the slower users is complete. Packet aggregation can reduce the loss of airtime and enhance the throughput without affecting the delay by filling in the gaps with additional packets which are ready for transmission. In this paper, the throughput is determined analytically and by simulation with and without packet aggregation for some given distribution functions of the packet size and the transmission time. For a more realistic channel model, the throughput enhancement due to packet aggregation is determined by simulations. It is shown that dependent on the distribution of the different flows, a significant throughput enhancement can be achieved.

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“…To cope with these requirements, in the framework of the xLAYER project funded by the German Research Foundation (DFG), a cross-layer transmission system for wireless LANs was introduced in [9] and extended by QoS support in [10]; the OFDMA/SDMA platform which means the parallel transmission to multiple users was introduced in [5].…”

Section: Introductionmentioning

confidence: 99%

“…In each turn of the scheduling process, the MAC scheduler assigns a priority to the data packet at the top of each queue according to a certain schedul-ing scheme. Different scheduling schemes were compared in [10], where also a scheduling method with quality-of-service support was proposed and investigated. In this scheduling method, which is also used for the investigations in this paper, the throughput is monitored by observing the number of successfully transmitted packets inside a sliding window and compared against the target value.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a QoS Aware Cross-Layer Scheduler by Packet Aggregation

Könsgen

Islam

Timm‐Giel

et al.

Wireless and Mobile Networking

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In this paper, the performance of a QoS-aware two-stage cross-layer scheduler utilising a MIMO channel for transmission is considered along with TDMA, OFDMA and SDMA channel access methods which serves a number of users with QoS-constrained data flows. OFDMA and SDMA allow a parallel transmission of packets which can have different transmission durations due to varying physical bit rates and packet lengths. The data flow with the longest packet slows down the other flows because they have to wait until the transmission is complete. This paper proposes packet aggregation where waiting times are reduced by transmitting more than one packet per user if airtime is left. It is shown that this method significantly enhances the QoS parameters throughput and delay. For constant-size packets, shorter delays can be achieved than for variable-size packets. Aggregating non-consecutive packets further enhances the performance, however the packets have to be buffered at the receiver to put them into the correct order. IntroductionWireless LANs have to meet increasing requirements nowadays and in the future: high data rates for each user, high spectral efficiency in the sense of a high total capacity and meeting several types of QoS requirements for different applications.Up to now, most protocols stacks are designed according to the OSI model which defines seven layers from the physical layer up to the application layer, with an increasing degree of abstraction from the physical hardware. In legacy protocol stacks, these different protocol layers have been optimised independently of each other. This separation is in particular problematic for the design of the two lowest layers, which are the MAC and the PHY layer, because there are close mutual dependencies between these two layers. The QoS requirements have already to be considered by selecting the physical transmission method. Moreover, the actual channel conditions and the effects of these conditions for a QoS aware transmission have to be known when selecting a particular packet for the transmission.Please use the following format when citing this chapter:

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An Enhanced Cross-Layer Two-Stage Scheduler for Wireless LANs

Cited by 6 publications

References 8 publications

Optimized packet formation in multi‐level security wireless data acquisition networks

Optimized packet formation in multi‐level security wireless data acquisition networks

Performance Analysis of Packet Aggregation in WLANs with Simultaneous Multi-user Access

Optimization of a QoS Aware Cross-Layer Scheduler by Packet Aggregation

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