Main achievments

1
Main achievments

• LOOP

Valdemar Monteiro
2
Outline

• Problem and motivation
• Cross-layer proposal and results
• INTEROPERABILITY
• Conclusions and future work

3

• 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
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
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

LThj is the threshold load for RAT j
6
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
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
Conclusions and future work (cont.)

• 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).