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									Chapter 2: Packet Scheduling and Congestion Control
System efficiency is an important requirement for wireless communication systems to provide broadband services to mobile users. Whereas, QoS support is mandatory for end-users who do not care about resource utilization, but expect a good service level. System optimization and QoS support are typically conflicting needs that can be solved by means of a suitable cross-layer system design and by exploiting the multiplexing effect of packet data traffic. Resource management is an important research field in wireless communications systems. The interest of this chapter is to focus on resource management for multimedia traffic flows with differentiated QoS support. A special attention will be provided to related issues such as the interaction of resource management at layer 2 with higher layer protocols (i.e., application, transport and network layer). This study will be then also addressed in exploiting such interactions in order to improve the system efficiency. The cross-layer design requires interfaces between non-adjacent layers. In general, a layer should be aware of the other layers of the protocol stack. Although interfaces between adjacent layers are in general preferable, there is need for direct interaction between non-adjacent layers. In general, a layer should be aware of the other layers of the protocol stack. The envisaged wireless technologies in this Chapter are: WCDMA, HSDPA, UMTS LTE, WiFi, WiMAX, GEO sat. This chapter is organized as follows. After an introduction, service differentiation is described. Then, resource management schemes for wireless systems are addressed. Then, congestion control and the impact that the wireless scenario has on the transport layer performance are concerned. Finally, cross-layer issues are presented focusing on different possible interactions.

NOTE: For the contributions below that are highlighted in yellow I have received the extended version
2.1 Introduction
On the topics addressed in this chapter and the related wireless technologies.

2.2 Service Differentiation [general issues, not related to a specific wireless technology]
Sub-Section Leader: Edmundo Monteiro, University of Coimbra ( Scenario Title
Classification of service disciplines A new approach to service differentiation: non-congestive queuing NSIS-based quality of service and resource allocation in Ethernet networks Multiservice Communications over TDMA/TDD Wireless LANs A Novel IEEE 802.11e-based QoS Protocol for Voice Communications over WLANs

University of Stuttgart, Germany Democritus University of Thrace, Greece University of Coimbra, Portugal


Universidad de Castilla La Mancha, Spain Universidad de Castilla La Mancha, Spain

2.3 Radio Resource Management [for different wireless technologies]
Sub-Section Leader: Michal Ries, technical University of Vienna ( Scenario

Orthogonal-variable-spreadingfactor code allocation strategy using

Polytechnic University of Bucharest



Cellular systems, in general UMTS/MBMS

genetic algorithms Novel buffer management scheme for multimedia traffic in HSDPA Controlled contention-based access to the medium in ad hoc WLANs Interference coordination (IFCO) in OFDMA-based networks, such as 802.16e and 3GPP LTE Emergency services: resource management and QoS control Call Admission Control in UMTS – MBMS Networks & Power Control in UMTS – MBMS Networks

University of Glamorgan, UK, Belarusian State University, Belarus University of Antwerp – IBBT University of Stuttgart, Germany [late submission] University of Split, Croatia (moved to another chapter) University of Cyprus

Received additional contribution

2.4 Congestion/Flow Control [general issues, not related to a specific wireless technology]
Sub-Section Leader: Vasos Vassiliou, University of Cyprus ( Scenario Title
Max-min congestion control schemes Open Box Transport Protocol (OBP) Assessing the Impact of Skype Flows on the Stability of the Internet Congestion control with explicit router feedback – Quick-Start TCP

University of Cyprus University of Coimbra, Portugal, Politecnico di Bari, Italy Politecnico di Bari, Italy University of Stuttgart, IKR, Germany

2.5 Transport Protocols over Wireless [for different wireless technologies]
Sub-Section Leader: Giovanni Giambene, University of Siena ( Scenario
IEEE 802.11e, EDCA

Cross-layer experimental study for IEEE 802.11e in the presence of TCP and UPD flows EDCF parameters selections for different ACs for QoS support A Smart TCP acknowledgment approach for multihop wireless networks Effects of satellite links on TCP performance and media delivery Providing Energy Efficient Real-time Services using HCC

UNISI, Italy TUT, Finland University of Würzburg, Germany Universität Bern, Switzerland [this contribution has been moved to Chapter 5] Democritus University of Thrace, Greece Politecnico di Bari, Italy

IEEE 802.11e IEEE 802.11

GEO sat IEEE 802.11e, HCCA

2.6 Cross-Layer Approach [for different wireless technologies]
Sub-Section Leader: Mari Carmen Aguayo Torres ( Scenario
Survey of other TD contributions on PHY and MAC cross-layer

Advanced QoS-scheduling techniques at the radio interface

University of Malaga, Spain


interaction, general scenario Cross-layer study involving applications parameters, transport layer and buffer space at the data-link layer, general wireless system, modelling efforts Survey level

Cross-layer performance control of wireless channels

TUT, Finland

IEEE 802.11e, layer 2, routing

IEEE 802.11e, QoS support for H.264 video streams at both data link and network layers EDCF, mixture of traffic, cross-layer involving layer 2 and application UMTS/HSDPA

GEO sat

Survey of network-centric (crosslayer) methods to improve video streaming QoS A cross-layer optimization for admission control enabled ondemand routing Cross-layer architecture for H.264 video streaming in heterogeneous DiffServ networks Joint admission control and adaptive VoIP codec selection policies in multi-rate WLANs Improvement of video streaming QoS by application-aware queue management in UMTS/HSDPA networks Provisioning of video streaming services in HSDPA via GEO Satellite

University of Stuttgart, Germany

Haute Alsace University, France

Technical University of Cluj-Napoca, Romania Universitat Pompeu Fabra, Spain Politecnico di Torino, Italy University of Stuttgart, Germany

UNISI, Italy TWIEN, Austria

2.7 Conclusions Few sentences to comment about packet scheduling and congestion control. Also future trends (future areas of interest) would be interesting to be discussed.


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