WINLAB

Joint Work: WINLAB, NECLA, NICTA

A Brief Tutorial on WiMAX setup using OMF

WINLAB

Overview• System architecture• Control API• Use of the VM Grid service to setup an experiment• Example scenario

WINLAB

Prototype Architecture

ASN Substrate

vBTS SubstrateCo

ns-

wm

-02

eth

2

Co

ns-

wm

-03

eth

2

Outdoor Network

eth0

eth1

InstrumentationNetwork

InternalNetwork

Base Station (BTS)eth1

eth1

eth0

OutsideWorld

10.3.0.61

10.3.0.73

Outside Bus (Trunk)

10

.0.1

02

.31

0.0

.10

2.2

VM Bus (Trunk)

Original ComponentsOf the BTS

WINLAB

API Architecture

WINLAB

Baseline Experiment Setup Steps• Admin Functions

• User commands:– (1) Create/Destroy Slice – (2) Start/Stop Slice– (3) Add Client

• RF API– Discussed in detail on the Wiki

WINLAB

Baseline Admin. Functions• Initialize the grid service:

– wget http://wm-asngw-02:5012/wimaxvm/initvms • Initializes the VM grid service• Checks for running VMs and initializes datapath on the machine

• List all running slices in XML format:– wget http://wm-asngw-02:5012/wimaxvm/vmlist

• Allows the administrator to have a detailed view of the running VMs• Shows VM statistics in XML format

WINLAB

Start and Stop Slice• Functionality:

– Starts/Stops VM instance– Configures VLANs on VM substrate

• wget http://wm-asngw-02:5012/wimaxvm/start?vmname = vm1

• wget http://wm-asngw-02:5012/wimaxvm/stop?vmname = vm1

WINLAB

Add Mobile• Functionality:

– Registers a client with the slice– Currently adds default service flow settings for the

client– Adds mapping to the datapath controller on ASN-

GW

• Call:– wget http://wm-asngw-02:5012/wimaxvm/addclient?vmname = vm1\

& clientmac = 84:22:10.14.2b.9a

WINLAB

Mock Experiment Sequence• Mobile associates, gets added to default slice, starts UL traffic• Slice user starts a new slice, adds the mobile to its slice• Datapath switch from (Mobile – VM0) (Mobile – VM1)

PhysicalBTS

ASN-GW

Default Slice (VM-0)

User Slice (VM-1)

AirInterface

WINLAB

Thanks.

WINLAB

Appendix

WINLAB

Project Overview• The project leverages a commercial 802.16e base

station from NEC.

• We build an open software controller around a standard WiMAX BTS for allowing integration and use as a part of the GENI framework.

• The setup should support sharing of the BTS and provide layer 2/3 programmability.

WINLAB

BTS Virtualization• Virtualization

– Abstraction• Provide the illusion of

owning the entire hardware to each slice

– Programmability• Sufficient degree of freedom

to every experimenter

– Isolation• Control and prevent the

impact of one slice on the other

PhysicalBTS

Each user sees an independent BTS

Isolation

• Slice – refers to the share of the resources owned by a particular user.

User A

User B

Terminology

WINLAB

Challenges In Sharing The BTS• BTS framework should be time shared in such a way

that every experimenter/slice :– Has the illusion of using the entire BTS

• Similar or scaled delay/throughput characteristics• Similar access interface

– Has similar control to the BTS• Adding its own set of clients, custom service flows• Can run an IP independent protocol stack

– Has minimum coupling with experiments from other slices

WINLAB

Why have an ``Open” Basestation?• Capabilities of an open basestation:

– Access to the experimenter community– Measurement and data collection from the framework– Control over some BTS parameters

• Driven by the NSF GENI* initiative– A large federated testbed infrastructure with wireless

edges

• Allows shift of research: Simulation Prototyping

* http://www.geni.net

WINLAB

Range of experiments• Longer range for a control channel

– Outdoor mobility: Vehicular, and or walking.– Collection of GPS traces, sensor measurement, …

• Allows evaluation of end – to – end links– Used in conjunction with a wired experimentation backbone

such as PlanetLAB or VINI• With enough Basestations:

– Evaluate a service with ``real” traffic– Comparing Handoff mechanisms

• Optimization and evaluation of transport mechanism for performance over cellular wireless

• Performance evaluation of a wide area network• Security

WINLAB

Envisioned Architecture

• Experimenters include the BTS as a part of their experiments

• Backbone is time shared ..so.. How do we share the BTS?

GENI terminals(WiMAX phone/PDA running GENI/Linux)

Virtual GENI Router (at PoP)

GENI BackboneNetwork

GENI Access Network

(Ethernet SW &Routers)

GENI Compliant WIMAX Base

StationController

WiMAX Base Station (GBSN)

WINLAB

Design & Implementation

WINLAB

BTS Hardware

Roof mounted Antenna

• Operational with an educational license• Inherently IP based

Basestation (IDU) Unit

RF (ODU)Amplifier

WINLAB

Major additions and changes• All packet forwarding is now L2

– Eliminated all IP routing from the datapath

• Provided API within each virtual machine to interact with the BTS– Similar features to that provided on the raw BTS

(Add client, remove client, setup service flows …)

• Mechanism for isolation between slices– VNTS traffic shaping mechanism

WINLAB

vBTS Architecture

• Redirect all traffic from VLANs to individual slices• Similar redirection from slices to outbound VLAN interfaces• Grid services for creation, destruction, maintenance of slices,

adding clients, slice allocation control …

Virtual machine instances

Dynamicallycreated VLANs

ASN Substrate

vBTS Substrate

Base Station (BTS)

WINLAB

ASN Packet Forwarding

• Removed all default IP routing, simplified ASN controller*• All switching purely based on MAC addresses• Implemented the VNTS shaping mechanism in click for slice

isolation

ASN Substrate

vBTS Substrate

Base Station (BTS)

* Work done at NEC

WINLAB

BTS

• The BTS itself is a black box• Hence, the slice isolation mechanism and control framework

is outside of this box

ASN Substrate

vBTS Substrate

Base Station (BTS)

Un-modified WiMAXBTS

(Black box)

DataAndControlPipes

WINLAB

Baseline Measurement

WINLAB

Coverage map of the WiMAX BaseStation

MeasuredRSSI

WINLAB

Demo Setup at GEC6• Goal:

– Show the effectiveness of our shaping mechanism for providing isolation across slices

• Setup:– 2 Clients (1 per slice)

– Stationary client in control room (CINR =31)

MobileSlice

StationarySlice

Open WiMAX BTS

MobileClient

StationaryClient

WINLAB

Path For The Mobile

• UDP CBR traffic: 1024bytes, 10Mbps/Slice

• Mobile client moves as shown

• Measured RSSI along the mobile client’s path

WINLAB

DL Throughput Vs Time – no shaping

Observed UDP Throughput

• No isolation among clients without VNTS• BTS is throughput fair

– But, air-time fairness is voilated

WINLAB

With VNTS

• Performance improves significantly– Good overall throughput performance– Improvement in isolation

DL Throughput Vs Time – VNTS

Good aggregate throughput

Isolationimproves

WINLAB

Future Steps• Tighter integration of the control framework• Better algorithms to adaptively shape client traffic• Similar control mechanism for UL slice traffic

WINLAB

BTS Specification

PHY

Access mode SOFDMA/TDD

Frequency 2535 ~ 2605 MHz

DL:UL ratio 35:12, 26:21, 29:18

Channel BW 10 MHz , 8.75 MHz

FFT size 1024, 512

Frame duration 5ms

TX output Power 35dBm (max)

# of sectors 3

MAC

Head compression PHS

ARQ HARQ/CC, ARQ

MBS support Single BS, multiple BS-MBS

Resource management

Power control, mode control (idle, sleep etc.)

Networking

IP protocols IPv4, IPv6

Bridging/Routing Transparent L2 switch, Bridging

Packet handling 802.1Q VLAN, PHS**)

rtPS real-time polling service

ertPS enhanced real-time polling service

nrtPS non real-time polling service

UGS unsolicited grant service

BE best effort

Base Station FeaturesSupported Service Classes

WINLAB

VNTS Mechanism

• Baseline algorithm for evaluating the shaping rate at the BTS• Modifications which account for retries are not included here

– Work in progress

WINLAB

Outdoor Measurements

2

3

WINLAB

Performance comparison

Fairness Index Coupling Coefficient