Aspects of Coexistence Between WiFi and HSDPA - UBI of Coexistence... · Aspects of Coexistence...

© 2005, it - instituto de telecomunicações. Todos os direitos reservados.

Aspects of Coexistence Between WiFiand HSDPA

Final Workshop of CROSSNET (Cross-layer design and network planning for B3G systems)

Orlando CabralValdemar Monteiro

2

Final Workshop of CROSSNET

| Lisboa, 19 de Fevereiro de 2008

Outline

• Global view of Cross-layer design and network planning for B3G systems (CROSSNET)• Cross-layer design• Cross-system and convergence

• Cross-layer studies for IEEE 802.11e• Differentiation mechanisms• Simulator validation• Cross-layer design proposal and results

• RAT selection for HSDPA and IEEE 802.11e• Interoperability scenario • Algorithm description• Results and scientific impact

• Conclusions and future work

3 | Lisboa, 19 de Fevereiro de 2008

Global view of CROSSNET - Objectives and work Organization

• The project was divided into three main areas: • Traffic modelling and Quality of Service (QoS)• Medium Access Control (MAC) definition and cross-layer

design• Network planning and optimisation, synthesis and integration

• In a scenario of heterogeneous networks, the interoperability among available radio access technologies should be seen by mobile users as the ability to successively attach to the access points and bases stations in a transparent way


4

Coexistence

| Lisboa, 19 de Fevereiro de 2008



Global view of CROSSNET - Cross-layer

• Implementation and validation of the High-Speed Downlink Packet Access (HSDPA) and IEEE 802.11e MAC protocol

• HSDPA R5 system level simulator facilitates the design, evaluation and optimization of scheduling and link-adaptation policies

text

NodeB

Channel Models

and Interference

Traffic Model

and Queues

Queue

Manager

DRA

L L IScheduler

Link

Adaptation

Power

Code

CQI

Slot

Radio

Resources

SIR

Cell Deployment and

Mobile Dynamics

H-

ARQ

H-

ARQ

UE

ARQ msg

(Ack/Nack)



Global view of CROSSNET - Cross-system

• MOTION (HSDPA) and WE-MOVE (WiFi) simulation tools were integrated under a common simulation platform to perform Common Radio Resource Management studies• RAT selection for multimedia services

• Also UMTS (HSDPA) – WiMAX interoperability is being considered, however at this stage the WiMAX simulation platform is being validated for IEEE 802.16e Dynamic Resource Allocation strategies



IEEE 802.11e – IFSs relationships

Priorities• SIFS (Short Inter Frame Spacing, IFS)

• highest priority, for ACK, CTS, polling response

• PIFS (PCF IFS)• medium priority, for time-bounded service using PCF

• AIFS (EDCA, arbitrary IFS, used by the QoS facility)• Priority depends of the access category.



IEEE 802.11e – Block ACK

• The Block Ack mechanism is initialized by an exchange of ADDBA Request/Response frames.

• After initialization, blocks of QoS data frames can be transmitted from the originator to the recipient.

0.0E+00

5.0E+06

1.0E+07

1.5E+07

2.0E+07

2.5E+07

0 10 20 30 40 50

Stations

Goo

dput

[b/s

]BK

VI

VO

VI-BLOCK

BK-BLOCK



IEEE 802.11 - State transition diagram



Validation PHY layer without fragmentation

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30

SINR [dB]

Goo

dput

[Mb/

s]

Mod 8Mod 7Mod 6Mod 5Mod 4Mod 3Mod 2Mod 1



Cross-layer concept used

OSI Model

BK BE VI VO

Virtual Collision Handler

Transmission

Attempt

Backoff

AIFS [0]

BC [0]

Backoff

AIFS [1]

BC [1]

Backoff

AIFS [2]

BC [2]

Backoff

AIFS [3]

BC [3]



Cross-Layer for WiFi EDCA mode

• Scenario Description• WiFi system where a cell has a set N+1 IEEE 802.11e stations

communicating through the same wireless channel• Station 0 is the Access Point or QoS Access Points (QAP),

and the other N wireless terminals are QoS stations (QSTA)

• Novelties of Algorithm• Dynamically changing the Arbitration Inter Frame Spacing (AIFS) and

the contention window (CW) size, using as inputs delay and channel state information, can lead to enhanced channel utilization and system QoS

• By sharing network state information among users, optimal radio resource allocation parameters can be attained



Cross-Layer for WiFi EDCA mode• Algorithm Description

• The algorithm is based on dynamically changing the CW and the AIFS to assign a priority

• Fairness is provided by using as an input the metric

• QoS is ensured by using as an input

• Results • The proposed cross-layer algorithm showed

enhanced performance for voice traffic• can support at least 35% extra stations

with QoS

• Future work will target optimisation for the remaining service classes (background, streaming, and best effort)

.)(

=poughputAverageThr

ePhyDataRatM

j

jj

.=)( ACK

ayCurrentDel

ACAC CayCurrentDeltDelayWeigh

0

100

200

300

400

500

0 10 20 30 40 50Stations

Del

ay p

er p

acke

t [m

s]

with scheduler-AP

without scheduler-AP

0.E+00

1.E+06

2.E+06

3.E+06

0 10 20 30 40 50

StationsG

oodp

ut [b

/s]

without scheduler-AP

with scheduler-AP



Conclusions- 802.11e Cross-layer Studies• The IEEE 802.11e event driven simulator allows the

evaluation and optimization of MAC protocols that includes acknowledgment policies and radio resource allocation strategies

• Utilizing a small CW for the voice access category leads to reduced goodput when the number of stations exceeds 65%

• Due to increased collisions causing the packet losses to exceed the retransmission threshold

• The proposed cross-layer algorithm showed enhanced performance for voice traffic

• Can support at least 35% extra stations with the required QoS



• This simulator will be extended:• to address the evaluation of interoperability protocols

for WiFi and HSDPA (in the context of the IT-MOTION tool)

• to investigate and validate Common Radio Resource Management (CRRM) techniques for HSDPA, WiMAXand WiFi

• Future work will target:• The joint application of block acknowledgment and

mixed traffic. • Handover policies between APs for multi-cell scenarios

Future work- 802.11e Cross-layer Studies


16

RAT selection for HSDPA and IEEE 802.11e


RAT selection for HSDPA and IEEE 802.11e- 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 WiFisystem



RAT selection for HSDPA and IEEE 802.11e- Algorithm description

• Suitability calculation for RAT selection among cells when new call is requested

• Targeted to flexible traffic• Flexibility imposes on the system, meaning that the service can be held

by each RAT

S (netw ork-centric suitability)

0

1

0 1 ηηηη

δδδδ

LThj

LThj is the threshold load for RAT j

>

−−

≤

=jji

j

ji

jji

ji LThcellLifLTh

cellL

LThcellLif

cellLS)(

1

)(1

)(1

))((,

2

,

,

,



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

• The goal is to optimize the load in each RAT, measuring the diversity gain in quality of service (QoS) provisioning



RAT selection for HSDPA and IEEE 802.11e- Results and Scientific Impact• Results

• 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 Radio Resources such that

the mobile assignment to different RATs is flexible and applicable to heterogeneous radio systems

0

500

1000

1500

2000

2500

3000

8 14 20 26 32 38 44

QoS

/ ser

vice

thro

ughp

ut (K

bps)

Number of user

CRMM vs HSDPA QoS Throughput

CRRM Goodput

NRTV offered load

HSDPA QoS



Conclusions and future work- HSDPA / WiFi CRRM studies

• CRRM was employed exploring the common management of the whole radio resources such that the assignment of mobiles to different radio technologies is flexible and considers the specific features of each system

• The goal of the proposed CRRM is to select the most appropriate radio network in co-located systems without deteriorating the quality of service

• Thanks to the CRRM algorithm, a 60% gain on system throughput (with QoS) can be achieved in a co-located HSDPA-WiFi system over HSDPA alone



Future work- HSDPA / WiFi CRRM studies

• CRRM future work includes• Evaluation of the proposed algorithm for the HSDPA and

WiMAX 802.16e• Improvement on the algorithm to include load balancing between

HSDPA and 802.16e for established connections

Thank you !

http://www.e-projects.ubi.pt/crossnet


Aspects of Coexistence Between WiFi and HSDPA - UBI of Coexistence... · Aspects of Coexistence...

Documents

Transcript of Aspects of Coexistence Between WiFi and HSDPA - UBI of Coexistence... · Aspects of Coexistence...