Wimax 802.16e QoS

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RFP Guidelines

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QoS Description

+File Name: QoS

Project:

Authors:

Comments Date

Version 0.1 27/6/2006

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RFP Guidelines


Table of Content

1. QoS Framework .......................................................................................................... 3

1.1. QoS Framework Reference Architecture in WiMAX .................................................................................. 4

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1. QoS Framework

In order to achieve Quality of Services, the whole network entities need to supportthe QoS requirements - CPE/MS/SS, wireless access network, the core network

and the application. All network layers are required to conceder the QoSrequirements and perform the policy according to the QoS.If one element in the network will ignore QoS requirements this can lead to result

where the whole network will no support the required SLA

The following mechanizes need to be implemented in order to achieve the required

QoS: -

Admission control ,

Packet Classification

Packet Prioritization according to Packet Classification

Packet scheduling, shaping and Queuing and dropping

SLA measurements and feedbacks

The core issue of providing applications over a mobile wireless network is the QoSsupport in the presence of changing network connectivity due to user mobility andshared, noisy, highly variable and limited wireless communication links.

QoS Framework provides capabilities to define, enforce, monitor and report SLAfor the mobile device and services it launches in the WiMAX access network

according to the standard-available toolset.

To maintain a specified QoS level, when the wireless link fluctuates or degrades, awireless system has to adapt to varying conditions. Adaptability of wireless

multimedia networks can also be made at different layers. At the application layer,most recent real-time applications are made to be able to adapt to changing

networking conditions. At the network layer, routing methods should adapt tomobility. At the data link layer, error correction mechanisms can be adaptive to

protect against higher and varying error rates of wireless links. Adaptability at the

physical layer is possible by choosing appropriate channel and power controltechniques.

Generally, QoS support in wireless networks is considered at two abstractionlevels: connection-level QoS and Application-level (or packet-level) QoS .

Connection-level QoS is often measured by two parameters – the new call blocking

probability, which measures service connectivity, and the handoff dropping probability, which measures service continuity during handoff (for a mobile user,

dropping an on-going call is generally more unbearable than blocking a new callrequest). Management of connection-level QoS requires a solution for radioresource allocation, call admission and resource reservation for new and handover

high priority calls.

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Application-level (or packet-level) QoS is related to perceived quality by end users,

whose service requests are connected and continued through connection- level QoSsupport. There is a set of parameters describing packet- level QoS, such as rate,delay, jitter, packet loss.

The two QoS levels are related to each other in the sense of resource allocation,which considers allocation among connection flows and among new and handoff

calls, through proper call admission control and resource reservation schemes.

The ability to provide the appropriate level of QoS for the specific Service Flowmay be decoupled to the following processes:

Ability to signal QoS requirements and recognize the correspondingService Flow;

Ability to evaluate, reserve and allocate the required resources;

Reporting capabilities for the provided QoS level (charging).

QoS aspects in ASN network may be discussed in the context of Managed andUnmanaged IP Services:

1.1. QoS Framework Reference Architecture in WiMAX

Deployment of mobile networks requires implementation of tunneling technology

for subscriber traffic from Traffic Anchor Point in CSN or ASN through outintermediate traffic anchor points (e.g. in ASN) to the actual point of MS

attachment in ASN (i.e. BS). Tunneling is required to handle IP traffic of asubscriber moving its physical point of attachment across different IP nodes inaccess network without modifying its own IP address. Another reason for

tunneling is to support “roaming” subscribers – allow different subscribers fromdifferent IP domains to co-exist in the same IP realm of the access network.

The tunnels for subscriber service flow in ASN is called Data Path. The QoS

Framework is responsible to handle subscriber service flow establishment, deletionand modification and it’s association with data path. Data Path management

consists in GRE Keys negotiation on each GRE interval along data path upon data path establishment

WiMAX NWG reference architecture related to QoS framework in Rel.1 is presented on the figure below:

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RFP Guidelines


Figure 1-1: WiMAX NWG reference architecture related to QoS

The QoS Framework reference architecture is presented on the figure below:

AF

Home NSP

PF

Subscriber

Data

ASN

MS

Admission

Control

Local

Resource

Info

SFMSFA Control Fn

SFA

R1

R6

R4

LPF

Local

Policy

Data

SFA Relay Fn

Data Path FnData Path

Fn

SFA

Relay

Fn

Data

Path

Fn

Via R3 & R5

R4

Anchor

Data Path Fn

Serving

Data Path Fn

Home AAA

server/

Policy Function

Authenticator

Traffic Anchor /

Anchor ASN GW

(FA)

Serving ASN GW

BS

Authenticator is

updated who is

the traffic anchor

point as a part of

HO

Not changed

during HOAF

Home NSP

PF

Subscriber

Data

ASN

MS

Admission

Control

Local

Resource

Info

SFMSFA Control Fn

SFA

R1

R6

R4

LPF

Local

Policy

Data

SFA Relay Fn

Data Path FnData Path

Fn

SFA

Relay

Fn

Data

Path

Fn

Via R3 & R5

R4

Anchor

Data Path Fn

Serving

Data Path Fn

Home AAA

server/

Policy Function

Authenticator

Traffic Anchor /

Anchor ASN GW

(FA)

Serving ASN GW

BS

Authenticator is

updated who is

the traffic anchor

point as a part of

HO

Not changed

during HO

Figure Figure 1-2: WiMAX NWG QoS Framework Reference Architecture

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RFP Guidelines


The following functional entities are defined in the QoS Framework:

Home AAA Server – the entity in CSN network, which identifies the MS andholds MS Authorization profile. MS Authorization Profile in H-AAA server should

include also the description of pre-provisioned service flows.

PF – the entity in CSN network, which communicates dynamic service flowestablishment with Application Function and ASN network. PF also applies CSN

network policy to the service flow establishment requests. PF is collocated toHome AAA server for a given MS.

Anchor SFA - is the entity in ASN network, which communicates service flow

establishment info with CSN network elements (AAA, PF) and ASN elements.From ASN perspective, it is the entity, which initiates service flow establishment

in ASN and also applies ASN-level policy decisions using a local policy database

and an associated local policy function. Anchor SFA provides mapping betweenCSN and ASN service flow identities. In Alvarion profile, Anchor SFA is co-

located with Anchored Authenticator and don't move during Handoff so PDF don'thave to maintain tracking of mobile movements in the ASN

SFA relay entities are defined in ASN GWs acting as FA/ Traffic Anchor GW andServing ASN GW on the bearer path towards SFM/BS

SFM resides in the Serving BS and enforces connection establishment requests

coming from SFA for the specific MS. This entity implements Admission Control(and AC-related) functionality and Scheduler functions. It is responsible for the

admission, creation, activation, modification and deletion of service flows on theair interface (on demand from SFA) and for actual QoS enforcement in sharedradio environment.

MS – Responds to IEEE 802.16e-defined service flow creation requests from BS.Classifies traffic according to the service flow descriptor. Performs traffic shapingin UL direction. May support client-originated (L2 and/ or L3) resource reservation

mechanisms.

There are signaling defined across R6/ R4 and R3 Reference Interfaces :

R6/ R4 – Intra-ASN signaling for Service Requests and Service Authorization primitives;

R3 – CSN – ASN signaling for Service Requests and Service Authorization primitives.

WiMAX defines treatment of pre-defined and dynamically established (on demandfrom application entity) connections in the access network to serve Un-managedand Managed Applications.

Un-managed (vs. managed) applications are not able to signal the application start,stop and traffic profile to access network.

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Traffic related to Un-managed Applications will be established over un-managed

(pre-provisioned) connections while traffic related to Managed Applications willuse connections established on demand from the Application entity. The followingtext makes use of terminology:

Un-managed connection and pre-provisioned connection terminology are usedin a similar way having in mind Un-managed applications;

Managed connection and dynamically established connection terminology areused in relation to Managed Applications.

1.1.1. Service Profile description in the SFM/ BS - QoS

Enforcement Point

WiMAX NWG specifies that IEEE 802.16e/d-defined Service Types andDescriptors will be transferred from SFA to SFM (BS) in admission control andconnection setup primitives. On top of it, NWG will consider other parameters

(e.g. Flow Type, etc.) that describe traffic nature and can be useful in policyenforcement point such as BS (SFM).

IEEE 802.16e/d specifies the following parameters:

Service Types:

UGS;

VBRert

VBRrt;

VBRnrt;

BE.

IEEE 802.16e/d specifies the following parameters available for service

description per UL or DL connection:

Traffic priority (values 0-7);

Maximum sustained traffic rate (bps) Maximum traffic burst (bps)

Minimum reserved traffic rate (bps);

Maximum latency (ms);

Fixed-length versus variable length SDU indicator;

Tolerated jitter (ms);

Unsolicited grant interval;

Unsolicited poll interval

Uplink grant scheduling type (BE, nrtPS, rtPS, UGS);

SDU size;

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Note: generally, there is no difference for managed and unmanaged services in

description of service flow in BS. There should be appropriate policy functionsaccurately mapping application requests/ pre-provisioned connections into ASNservice class, type and descriptor. In order not to consume unused recourses, there

is a sense to define pre-provisioned connections using BE service type only.

Non-802.16e parameters (NWG and partner companies):

Connection profile / traffic priority?

Applicat ion Type (some ID enabling BS to reserve minimum resources for

the specific application type – e.g. guarantee some minimum resources for voice calls)

Flow Type (e.g. audio, video, etc.) – parameter describing the nature of

application traffic

Pre-provisioned connection or dynamic (managed) connection indicator.

Note, that currently, this is not a part of specifications.

Note: the BS should be able to make AC and Scheduling decisions without the

parameters that are not a mandatory part of implementation profiles.

The following Service Descriptors are defined for different Service Types:

Classification UGS VBRert VBRrt VBRnrt BE

Max sustained rate + + + +

Max traffic burst

Min reserved rate + + + +Min tolerable traffic

type

Tolerated jitter + +

Max latency + + +

Traffic priority + + + + (O)

Request/transmission

policy

+ +

u, d *

+

u, d *

+

c, u, d *

+

c, u, d*

Unsolicited Grant

Interval

+ +

Unsolicited Polling

Interval

+

SDU size +

Vendor-specific

Uplink grant

scheduling type

UGS UGS rtPS nrtPS BE

Notes: * - c (contention request), u (unicast request), d (data transmission)

opportunities;

There is a specific treatment for connections with CIR in their service descriptor (mainly relevant for Managed connections), which requires periodic allocation of

UL resource for the connection lifetime (unsolicited poll interval, unsolicited grantinterval).

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1.1.2. Managed IP Services

Managed Services (Applications) are characterized by the correlation of

Application session control with Resources Allocat ion process, which takes care of

the required resource allocation (at least in the access network). Admission Control process is performed just after application setup is initiated and the results of it are

delivered to an Applicat ion Server/ Client before the application setup isconfirmed. The Application makes the decision to accept or deny application setup

based on the results of Admission Control process:

It will proceed with application setup only upon positive AdmissionControl response.

In the case, Admission Control results indicate there are no resourcesavailable (answering the applicat ion demand), the specific application

session will be gracefully shut down by the Application (applicationsession setup signaling in coordination with DQoS AC process).

The standard driving Managed Services in wireless environment currently is3GPP/2 IMS (future TiSPAN may be considered also). The WiMAX architecturewill adopt itself to IMS reference model:

WiMAXWiMAX

MSMSWiMAX SFMWiMAX SFM

(BS)(BS)WiMAX SFAWiMAX SFA

(ASN GW)(ASN GW)PP--CSCF,CSCF,

IMSIMS

WiMAX ASNWiMAX ASN IMSIMS

IP BS Manager

IMS PEP

WiMAX BS

Manager

WiMAX SFA

(PCF)

WiMAX SFM

(WiMAX PEP)

WiMAX BS

Manager

Translation/

Mapping

IP BS

Manager

QoS profile

Translation/

Mapping

R6/ R4

Data Path Control

R1

802.16e (DSx)

Go

COPS

SIP/ SDP

PDF

Application

Client P-CSCF

Gq

WiMAXWiMAX

MSMSWiMAX SFMWiMAX SFM

(BS)(BS)WiMAX SFAWiMAX SFA

(ASN GW)(ASN GW)PP--CSCF,CSCF,

IMSIMS

WiMAX ASNWiMAX ASN IMSIMS

IP BS Manager

IMS PEP

WiMAX BS

Manager

WiMAX SFA

(PCF)

WiMAX SFM

(WiMAX PEP)

WiMAX BS

Manager

Translation/

Mapping

IP BS

Manager

QoS profile

Translation/

Mapping

R6/ R4

Data Path Control

R1

802.16e (DSx)

Go

COPS

SIP/ SDP

PDF

Application

Client P-CSCF

Gq

Figure 1-3: QoS enforcement in IMS-WiMAX - Reference Model

There are two stages in Admission Control process:

Application Authorization stage – Application Server/ Policy DecisionFunction should authorize application request. It is done by an AS/PDF in

ASP/CSN network and is correlated to the second stage;

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Actual QoS Admission Control stage. It may be started by an application

agent in a Client or in a Server (Server-originated Admission Control iscurrently preferred mode) and is proceeded through out the specificfunctional entities in ASP/CSN and ASN networks called Policy Decision

Functions (Service Flow Authorization function);

Admission Control process results in the requested Resources Reservation. Actual

Resource Allocation is conducted when Application traffic flow

MS node is responsible for traffic classification in UL direction. It will classify packets coming from Application Client in SS and direct them to the appropriate

CID. It is also responsible for traffic shaping in UL direction.

1.1.3. Unmanaged IP Services

There is no Resource Reservation process originated by Applicat ion Agents (client

or server) for unmanaged IP Services. Application session will be defined as activeupon detection of the stream of packets and end of session will be a time-outinterval after last packet of the stream.

WiMAX access network will support unmanaged IP Services based on thesubscriber service profile (part of subscriber SLA). This subscriber service profile

is a set of Traffic Descriptors and Traffic Classifiers and is pre-provisioned in theHome AAA server. Upon successful accomplishment of the subscriber authentication process, the subscriber profile will be transferred to the ASN GW

acting as Anchored Authenticator/ SFA and it will originate data path(s)establishment according to this profile.

Application session will start without BS Admission control function decision.

In the case radio resources are BW-limited, BS will regulate traffic load by:

Dropping packets in DL direction (DSCP field in original IP header may be

taken into account);

Regulating UL map allocation in UL direction (MS will drop packets in UL

direction under some conditions. May be done taking into account DSCPfield in IP header.

BS is responsible to provide appropriate Accounting Record per service flowreflecting radio resource utilization

The proposal for Service Differentiation based on traffic prioritization accordingto pre-provisioned subscriber or service privileges/ policy:

The target is:

Enable subscriber traffic differentiation dependent on:

o Subscriber pre-provisioned profile (e.g. Gold/ Silver/ Bronze/ ..) or

Traffic Priority parameter set per pre-provisioned connection

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o Subscriber pre-provisioned Maximum Sustained Rate – can be used

to provide voice for unmanaged services

Use pre-provisioned common service behavior in access – define BE

service class with minimum committed rate per such service class but not preventing BW usage if there is no demand from other services

Prevent usage of pre-provisioned guaranteed rate for the specific Service

Flow in Mobile environment

1.1.4. Service Description parameters in PF/ H-AAA server

The following MS context and service description parameters are planned to be

supported by Policy Function and SFA-PF communications at the time frame asdefined by WiMAX NWG Stage 2:

MS Context:

MS ID (or MS NAI);

SFA ID (IP Address or FQDN)

Service Description parameters:

Flow ID;

Application ID;

Direction;

Flow Status (provisioned, active, admitted, etc.);

Resource Description;

Flow Description/ Packet Classifiers;

Flow Type;

Priority;

Etc.

Policy Function should be responsible for proper managing of Transaction ID per

action requested from SFA.

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