1. © 2005, it - instituto de telecomunicações. Todos os direitos reservados. Main achievments LOOP Valdemar Monteiro

2. 2 LOOP | Aveiro, 5 de June de 2008 Outline Problem and motivation Cross-layer proposal and results INTEROPERABILITY Conclusions and future work

3. 3 LOOP | Aveiro, 5 de June de 2008  Scenario Description  Common coverage scenario with UMTS cell and with a WiFi hot-spot  IP-based core network assumed that acts as the bridge between WiFi, and HSDPA  NRTV services that can be streamed either over HSDPA, or WiFi system

4. 4 LOOP | Aveiro, 5 de June de 2008 RAT selection for HSDPA and IEEE 802.11e - Novelties of Algorithm  RAT selection based on load suitability where the systems are HSDPA and WiFi, under delay constraints services  Concept of suitability is used in terms of preferred access system to accommodate the service, where Suitability can change as load increase;  So, the goal is to optimize the load in each RAT, measuring the diversity gain in quality of service (QoS) provisioning

5. 5 LOOP | Aveiro, 5 de June de 2008 RAT selection for HSDPA and IEEE 802.11e - Algorithm description  Suitability calculation for load balancing among cells of different RATs when new call is requested;  Targeted to flexible traffic : Flexibility imposes on the system, meaning that the service can be held by each RAT LTh j LThj is the threshold load for RAT j

6. 6 LOOP | Aveiro, 5 de June de 2008 RAT selection for HSDPA and IEEE 802.11e - Results and Scientific Impact  Gain of 60% on the supported QoS load achieved with the CRRM (intelligently adapted algorithm) over HSDPA alone  Scientific impact : Exploring Common Management of the whole RR such mobile assignment of to different RAT is flexible, considering specific advantages of each system

7. 7 LOOP | Aveiro, 5 de June de 2008 Conclusions and future work Our IEEE 802.11e event driven simulator is a tool that allows for tuning-up several parameters like the ones related to how to use block acknowledgment, normal acknowledgment, and no acknowledgment policies. The use of small CW for the VO access category may not be a very good idea since when the number of stations is higher than 38 the goodput starts to decrease due to a small CW size. By suffering collisions successively the retransmission threshold is overcome causing the increase of packet losses. The proposed cross-layer algorithm, showed very good improvements for VO traffic as it supports at least 13 extra stations. Regarding results for VI traffic, an improvement as shown but it is not significant. We conclude that this algorithm still needs some tuning in order to produce better results, although the results are already very promising.

8. 8 LOOP | Aveiro, 5 de June de 2008 This simulator enables simulations accounting for inter-working with WiMAX and HSDPA (in the context of the IT-MOTION tool) allow for testing improvements on scheduling algorithms and Common Radio Resource Management (CRRM) techniques In future work, the results with mixtures of applications and block acknowledgement will be addressed. Handover policies between APs will also be an objective to be fulfilled, where a scenario using more than one cell can be supported. Later, our simulator will be integrated into the IT-MOTION simulator, and further work will be performed to optimise inter-working among different systems (e.g. Wi-Fi, HSDPA, and WiMAX). Conclusions and future work (cont.)