1. Covilhã, 30 June Atílio Gameiro Page 1 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential CROSSNET – IT AVEIRO Plans

2. Covilhã, 30 June Atílio Gameiro Page 2 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential IT- Aveiro Involvement in W2  Main Involvement – Task2 –MAC definition and Cross-layer design  Objectives of the task –1) Identification and transport of relevant cross-layer information (CLI) –2) Definition of a cross-layer (CL) architecture framework –3) Cross-layer strategies between PHY and MAC/RRM strategies  The following aspects / algorithms will be addressed: –Enhancement of distributed MAC/scheduling strategies so as to make extensive use of CL I –Exploitation of multi-user detection schemes, multipacket reception capabilities and space/components vs MAC/scheduling schemes –Conception of self adaptative MAC/scheduling functionalities able to self-adjust to time-varying availability or changes in CSI or resources available. –Work will resort to simulations and analysis –Simulations: system level simulator developed under the framework of other projects will be upgraded

3. Covilhã, 30 June Atílio Gameiro Page 3 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Why Cross –layer ?  Main characteristic of wireless networks  randomness –Network topology is not fixed (users move, enter, leave the network...) –Link characteristics vary with time, position

4. Covilhã, 30 June Atílio Gameiro Page 4 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Why Cross-layer - Quality of Service I  Trends in telecommunication networks –Provide end to end quality of service different traffic types get different levels of network service  Characteristics used for QoS –Bandwidth allocation ( bandwidth: misnomer for data rate ) –Delay bound –Jitter bound ( Jitter = variation in delay ) –Loss rate

5. Covilhã, 30 June Atílio Gameiro Page 5 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Why Cross-layer - Quality of service II  What are the issues associated with QoS provision? –Isolation / sharing Provision of individualized quality communication guarantees facilitated if different flows are isolated Isolation is inherent in circuit switched networks but in the current Internet (IP) all flows share all resources at the packet level. Ensuring QoS requires isolation However too much isolation lower the resource utilization  To support QoS in IP network, need to emulate the traffic isolation while sharing resources at the packet level –Delay bounds IntServ requires scheduling to support delay bounds. Delay bounds reflect the trade-off between isolation and sharing.

6. Covilhã, 30 June Atílio Gameiro Page 6 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Why Cross-layer - Quality of Service III  Provision of QoS services generally involve putting in place mechanisms that ensure –Fairness - access to network resources –Isolation - protection from excessive usage of network resources from other users Subject to general goals of –Efficiency –Complexity

7. Covilhã, 30 June Atílio Gameiro Page 7 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Why cross-layer - Quality of Service V  To reach these goals in packet switched networks requires collaboration of many components –Admission Control –Scheduling Which packet gets transmitted first on the output link significantly impacts QoS guarantees for different flows. –Scheduling affects delay, jitter and loss rate. –Allows protection against misbehaving flows. –Buffer Management –Congestion Control

8. Covilhã, 30 June Atílio Gameiro Page 8 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Why Cross-Layer - QoS and Scheduling  Scheduling is a major component in the QoS scheme  There are conflicts in a packet switched network between –The goal of sharing resources –The need to provide some flow isolation and fairness to guarantee QoS  Scheduler designed to maximize throughput does not answer these objectives  But these goals and implementation problems are not specific of wireless networks –also exist in the wired world to fullfill the quest of QoS provision  Are there solutions that can be imported?

9. Covilhã, 30 June Atílio Gameiro Page 9 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential QoS and scheduling – Wired vs Wireless I  There are some fundamental difference between wired and wireless networks –Wired networks: can assume time-invariant physical links in most cases Packet schedulers use information from the upper layers(QoS requirements, forwarding policies,…) to decide about which packets should be transmitted Scheduler PHY layer Upper layers Read QoS requirements / packet attributes, get forwarding policies

10. Covilhã, 30 June Atílio Gameiro Page 10 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential QoS and Scheduling – Wired vs Wireless II  What happens with wireless networks? –Dynamic topology: user moves around, also enter and leave –Quality of the wireless channel is typically different for different users, and randomly changes with time (on both slow and fast time scales). –Wireless bandwidth is usually a scarce resource that needs to be used efficiently (can not overprovision the wireless link). –Excessive amount of interference and higher error rates are typical.  A scheduling algorithm that does not account for this variability of the channel will have low efficiency would be for most scenarios very poor  wireless networks require scheduling algorithms that use the PHY layer information

11. Covilhã, 30 June Atílio Gameiro Page 11 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential QoS and Scheduling V  To provide QoS in packet switched wireless networks a cross- layer design approach is needed to design schedulers –Service requirements have to be taken into account –Physical layer information needs also to be considered Scheduler PHY layer Upper layers Get Channel State Information Read QoS requirements / packet atributes, get forwarding policies

12. Covilhã, 30 June Atílio Gameiro Page 12 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Cross-Layer Schemes - Concept  Concept RRM PHY layer L3 Channel estimation Provide CSI QoS requirements Read QoS requirements / packet atributes Takes decisions in order to optimize some cost / revenue function f(QoS,CSI)

13. Covilhã, 30 June Atílio Gameiro Page 13 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential RRM topics to be investigated  RRM for MIMO systems  Which RRM –Scheduling algorithms (ongoing work) –Joint scheduling / link adaptation and power assignement  Phase 1 –Consider the DL  centralized architecture  Phase 2 –Extend to UL Investigation of the different approaches –Centralized vs distributed –Still open

14. Covilhã, 30 June Atílio Gameiro Page 14 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Cross Layer  Work in paralel with algorithm development –Impact on architectures Signalling required, overhead

15. Covilhã, 30 June Atílio Gameiro Page 15 The information in this document is provided as is and no guarantee or warranty is given that the information is fit for any particular purpose. The user thereof uses the information as its sole risk and liability. project confidential Cross Layer  Past / Current work –Scheduling algorithms based on priority function involving CSI and delay SISO and MIMO –MIMO Radio resource reuse through beamforming and scheduling –Joint design of scheduler and link adapatation (modulation and coding selection) (ongoing)