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TIA/EIA/TSB-146)TR41.4-11-008

Project : PN-3-0102

Title : Wireless LAN based IP Telephony Subsystem

Source : Alcatel1 Route du docteur Albert Schweitzer67408 IllkirchFrance

Contacts : Raymond GassPhone : +33 3 90 67 77 02Fax : +33 3 90 67 70 18E Mail :raymond.gass@alcatel.fr

Date : 29th October 2004

Contributed to : TIA TR-41.4

The Source1 grants a free, irrevocable license to the Telecommunications Industry Association (TIA) to incorporate text or other copyrightable material contained in this contribution and any modifications thereof in the creation of a TIA Publication; to copyright and sell in TIA's name any TIA Publication even though it may include all or portions of this contribution; and at TIA's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting TIA Publication. The Source will also be willing to grant licenses under such copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing a TIA Publication which incorporates this contribution.

This document has been prepared by Alcatel to assist the TIA Engineering Committee. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on Alcatel. Alcatel specifically reserves the right to amend or modify the material contained herein and nothing herein shall be construed as conferring or offering licenses or rights with respect to any intellectual property of Alcatel other than provided in the copyright statement above.

The Source agrees that if the Source has changed or added text to the required language in the TIA contribution template as contained in the TIA Engineering Manual, any such change or addition which is inconsistent with such contribution template, is of no force or effect.

1 The owner of the copyright or license right, if any, submitted in the contribution.

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Draft- Requirements for a Wireless LAN-based IP Telephony Subsystem

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1. INTRODUCTION.............................................................................52. Scope........................................................................................................................................63. Normative reference.................................................................................................................64. Definitions, abbreviations and acronyms................................................................................74.1. Requirements language.......................................................................................................74.2. Abbreviations and acronyms...............................................................................................74.3. Definitions..........................................................................................................................85. Inter-working architecture....................................................................................................105.1. Reference model...............................................................................................................105.2. Network elements.............................................................................................................105.2.1. VoIP WLAN telephone....................................................................................................105.2.2. Access Point....................................................................................................................115.2.3. Communication Server.....................................................................................................115.2.4. WLAN Authentication server...........................................................................................115.2.5. Mobility agents................................................................................................................115.2.6. Media Gateway................................................................................................................115.3. Protocol stack reference model..........................................................................................115.3.1. User and control voice planes...........................................................................................115.3.2. Authentication plane........................................................................................................126. High level Requirements........................................................................................................127. Requirements and Procedures...............................................................................................157.1. Initialization......................................................................................................................167.2. QoS management..............................................................................................................167.2.1. Bandwidth management...................................................................................................167.3. Security............................................................................................................................167.3.1. WPA2/SA........................................................................................................................167.3.2. Authentication..................................................................................................................167.3.3. Key management..............................................................................................................177.3.4. Ciphering.........................................................................................................................177.3.5. Re-authentication.............................................................................................................177.3.6. End-to-End Security.........................................................................................................177.4. Mobility............................................................................................................................177.4.1. L2 handover.....................................................................................................................177.4.2. L3 handover.....................................................................................................................177.5. Management.....................................................................................................................177.6. Emergency calls................................................................................................................177.6.1. Congestion.......................................................................................................................177.6.2. Handover.........................................................................................................................187.6.3. Miscellaneous..................................................................................................................187.7. Control protocols..............................................................................................................197.7.1. SIP 197.7.2. H.323...............................................................................................................................197.7.3. H.248...............................................................................................................................197.8. Acoustic............................................................................................................................197.9. Test methodology.............................................................................................................198. Options for the corporate environment within the WFA specifications...............................198.1. Introduction......................................................................................................................198.2. PHY options.....................................................................................................................198.3. MAC options....................................................................................................................199. Appendix – Informative.........................................................................................................209.1. Encapsulation Frame format..............................................................................................20

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Foreword

(This foreword is not part of this Standard.)

This document is a TIA/EIA Telecommunications standard produced by Working Group TR-41.4 of Committee TR-41. This standard was developed in accordance with TIA/EIA procedural guidelines, and represents the consensus position of the Working group and its parent committee TR-41.

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2. Introduction

WLAN market, based mainly on the IEEE 802 .11 technology (and Wi-Fi certifications), is increasingly mature from the point of view of regulation, interoperability and offer variety. The applications using this technology are mainly data oriented. WLAN also offers the capability to have a mobile converged data and voice solution onto a single wireless infrastructure. A strong market requirement is emerging today, named VoWLAN (Voice over WLAN), based on VoIP mobile applications in multi-standard handsets (802.11/GSM/UMTS).

Considering an end-to-end telephony application, several equipments are concerned in the corporate environment for this interoperability: VoIP devices, WLAN Access points, networks equipments, Communication Servers, gateway …and a cooperation between at least Layer 1,2 and 3 are necessary.

The intent of this Standard is to conform to existing IETF, ITU-T, IEEE, ANSI, TIA, ETSI, and other standards; however, it is not the intent of this working group to duplicate the efforts of these other organizations.

This Standard is intended to be a living document. The criteria contained in this Standard are subject to revision and updating as warranted by advances in network or terminal equipment technology.

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3. Scope

This Standard specifies requirements for the access network including both wireless and wired networks enabling telephony communications for VoIP WLAN Telephones in a corporate environment. It does not address residential and Public Access WLAN environments.It should be read in close relationship with the TIA standard specifying the requirements for VoIP WLAN features Telephone defining the “VoWLAN profile” concept in the corporate environment.Due to the huge growth of the Wi-Fi products on the market, this present standard is focusing today on the IEEE 802.11 standards and drafts. Since many improvements are in progress within the IEEE 802.11 working groups in term of security, QoS, mobility especially enabling the voice traffic, this document will reference the 802.11x drafts and will be updated, if needed, at each new draft release (802.11e 802.11i, WSM/WME, WPA2/SA…). Also, these interoperability requirements should be applied to 802.11a,b,g but need to be checked in term of end-to-end performances.In the same way, the VoWLAN TIA requirements shall be compliant with Wi-Fi specifications both in an approved and progress state.

4. Normative reference

1. Wi-Fi Alliance 802.11x with WPA System Interoperability Test Plan. Version 2.2.

2. IEEE 802.11a- 2001 - Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5 GHz Band.

3. IEEE 802.11b - 2001 - Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Higher speed Physical Layer (PHY) extension in the 2.4 GHz band.

4. IEEE 802.11d - 2001 - Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 3: Specification for operation in additional regulatory domains.

5. IEEE 802.11e/Draft - 2004 - Wireless Medium Access Control (MAC) and Physical Layer (PHY) specifications: Medium Access Control (MAC) Quality of Service (QoS) Enhancements.

6. IEEE 802.11g- 2003 - Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications -Amendment 4: Further Higher Data Rate Extension in the 2.4 GHz Band.

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TIA/EIA/TSB-146)7. IEEE 802.11i - 2004 -Wireless Medium Access Control (MAC) and

Physical Layer (PHY) specifications: Amendment 6: Medium Access Control (MAC) Security Enhancements.

8. IEEE 802.11k/Draft - 2004 - Wireless Medium Access Control (MAC) and Physical Layer (PHY) specifications: Specification for Radio Resource Measurement.

9. IEEE 802.11r/Draft10. IEEE 802.11 TGe WME/Draft – 200411. IETF RFC’s: 3261 - SIP, 3264 - media negotiation (SDP

offer/answer), 2327 - media declaration (SDP)12. ITU-T H32313. Wi-Fi Alliance WSM/Draft – Wi-Fi Scheduled Multimedia (WSM)

Specification v0.09 200414. Wi-Fi Alliance – Tests matrix specifications

5. Definitions, abbreviations and acronyms

5.1. Requirements language

Two categories of criteria are specified: mandatory and advisory. Mandatory requirements are designated by the word “shall”. Advisory requirements are designated by the word “should,” or “may,” or “desirable” (which are used interchangeably in this Standard). The mandatory criteria generally apply to safety and protection, signaling, and compatibility; they specify the absolute minimum acceptable requirements in areas such as transmission and equipment parameters and durability.

Advisory criteria represent product goals. In some instances, the advisory criteria are included in an effort to ensure universal product compatibility with equipment and facilities operating in statistically small quantities. In other cases, advisory criteria are presented when their attainment will enhance the general performance of the product in all its contemplated applications.

Where both a mandatory and an advisory level are specified for the same criterion, the advisory level represents a goal currently identifiable as having distinct compatibility or performance advantages, or both, toward which future designs should strive.

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TIA/EIA/TSB-146)5.2. Abbreviations and acronyms

AES Advanced Encryption StandardAP Access PointAPSD Automatic Power Save DeliveryAS Authentication ServerCS Communication ServerDHCP Dynamic Host Configuration ProtocolDSS Distribution system serviceEAP Extensible Authentication ProtocolED Energy DetectEDCA Enhanced Distributed Channel AccessFCS Frame Check SequenceHCCA Hybrid Controlled Channel AccessIBSS Independent Basic Service SetIETF Internet Engineering Task ForceIP Internet ProtocolIPv4 Internet Protocol, version 4IPv6 Internet Protocol, version 6ISDN Integrated Services Digital NetworkMAC Medium Access ControlMGCP Media Gateway Control ProtocolMCU Multipoint Control UnitOUI Organizationally Unique IdentifierPSK Pre-Shared KeyPSTN Public Switched Telephone NetworkMA Mobility AgentMG Media GatewayQoS Quality of ServicePHY Physical LayerPSNI Perceived Signal to Noise plus interference RatioRADIUS Remote Authentication Dial-In User Service

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TIA/EIA/TSB-146)RCPI Received Channel Power IndicatorRTP Real Time ProtocolRTCP Real Time Control ProtocolRSSI Received Signal Strength IndicationSIP Session Initiation ProtocolSNAP Sub-Network Access ProtocolSNR Signal to Noise RatioTBD To Be DefinedTCP Transmission Control ProtocolUDP User Datagram ProtocolVLAN Virtual LANVoWLAN VoIP over WLANWFA Wi-Fi AllianceWPA Wi-Fi Protected AccessWPA1 Wi-Fi Protected Access version 1WPA2 Wi-Fi Protected Access version 2WME Wireless Multimedia EnhancementsWMM Wi-Fi MultiMediaWSM Wi-Fi Scheduled MultimediaWMM-SA Wi-Fi MultiMedia Scheduled AccessWT Wireless Telephone

5.3. Definitions

Connection: A connection identifies a flow of data between two points in the network. A VoIP connection is, for example an Internet RTP connection. In order for a WT to provide seamless mobility, connections must be transferred as the WT moves between Access Points.

Corporate network: An IP-based inter-network under the administration of one single company (i.e. an infrastructure consisting basically of LANs, WLANs, and routers).

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TIA/EIA/TSB-146)Handover: Handover is a process through which a WT moves from an Access Point to another Access Point in a corporate environment. L2 handover is a link layer handover (e.g. 802.11 using association/de-association procedures at the WT level). L3 handover is a layer 3 handover (e.g. Mobile IP). When a WT moves, it may generate L2 handover only or both L2 and L3 handovers.

Nomadic: Nomadic access refers to the interrupted operation of a WT. In this mode, all connections are terminated before the WT starts to move, and the connections are remade at the new endpoint. This is in contrast to seamless mobility where the individual connections are maintained

Roam: A WT roams within the (global) network when it moves from an access point of one service provider to an access point of a different service provider. This term is basically used in a cellular environment or in a WLAN hot spot environment.

Seamless: Seamless mobility is when a WT can move through a handover process in such a way that all connections having that WT as an endpoint are maintained.

Telephony over IP: Real-time Bidirectional and Symmetric voice (video) communications based on IP, using Multicast or Unicast facilities, Always-on, requiring Middle/Narrow bandwidth, Error tolerant and allowing a Delay between 10ms and 150ms. ToIP allows a better service integration with other IT applications.

VoWLAN: VoWLAN is the technology allowing VoIP over WLAN. Basically, the term VoIP is generic representing voice traffic in an IP world. In this document, it shall be considered as ToIP (Telephony over IP) in a corporate environment.

Wi-Fi Protected Access: WPA2 as the next compatible version of already existing WPA specification enhances security. It strongly increases the level of data protection and access control for WLAN systems. WPA2 is based on both WPA specification and 802.11i IEEE standard.WPA2 provides authentication using IEEE 802.1X and Extensible Authentication Protocol types (EAP). WPA2 provides data encryption via the Advanced Encryption Standard (AES).

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TIA/EIA/TSB-146)WPA2 offers a WPA-Personal and a WPA-Enterprise mode (or full WPA2). Both use AES for encryption, but the authentication is by Pre-shared Key for WPA2-Personal whereas the full 802.1X/ EAP authentication method is used for WPA2-Enterprise.

WME: IEEE 802.11 “Task Group e” is developing specifications called “Wireless Multimedia Enhancements” (WME) in an effort to early deploy interoperable QoS enabled Wi-Fi products before IEEE 802.11e standard is published. WME is a subset of the 802.11e standard, based on “Enhanced Distributed Channel Access” (EDCA) to provide a self-contain QoS mechanism.WMM: is a profile (defined in WFA) of the upcoming IEEE 802.11e QoS extensions for 802.11 networks. WMM prioritizes traffic demands from different applications (voice, music, and video) under a wide variety of environment and traffic conditions. WMM defines four access categories (voice, video, best effort, and background) that are used to prioritize traffic so that these applications have access to the necessary network resources.

WSM: The Wi-Fi Alliance is also developing “Wireless Scheduled Multimedia” (WSM) specification, which is based on “Hybrid Controlled Channel Access” (HCCA) of 802.11e standard. Because WSM must also support WME baseline, WSM will provide a platform for testing compliance and interoperability for both HCCA and EDCA.WMM-SA: The Wi-Fi alliance is also developing WMM-SA which is based on “Hybrid Controlled Channel Access” (HCCA of the 802.11e standard. Because WMM-SA must also support WMM baseline, WMM-SA will provide a platform for testing compliance and interoperability for both HCCA and EDCA.

6. Inter-working architecture

6.1. Reference model

The reference model of a VoWLAN architecture is depicted in the figure below.

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6.2. Network elements

6.2.1. VoIP WLAN telephone

The WT is a VoIP WLAN telephone acting as an end-system equipment providing the interface towards human beings through a set of applications. The WT includes, among other things, the functions and protocols necessary to provide and handle the telephony communications with the Communication Server system through the wireless and wired network. It supports the IP telephony stacks (H.323, MGCP, SIP).

6.2.2. Access Point

An AP is a functional entity, acting as layer 2-bridge network device, which includes interworking function between the wireless and wired interfaces at PHY and MAC layers. It may include one or more Access Point Radio transceivers and one Access Point controller.

6.2.3. Communication Server

The Communication Server is a software-based system within an enterprise that handles phone calls between enterprise and/or external users and offers applications related to multi-media Communication. Besides traditional telephony, it supports IP telephony (SIP, H.323) for users connected to the corporate network. This functional system may include sub-systems specific for each voice control stacks (i.e. MCU, Gatekeeper for H.323, or Proxy, Registrar for SIP).

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TIA/EIA/TSB-146)6.2.4. WLAN Authentication server

An Authentication Server provides authentication service to the Authenticator. The Authenticator requires the entity on the other end of the link to be authenticated.The authentication server may be co-located with Authenticator, but most likely an external server running RADIUS. It is mandatory when using WPA2- Enterprise mode (802.1X).

6.2.5. Mobility agents

Mobility Agents are functional cooperative entities located either on the same server or different machines that deals with but not limited to WT data collection and analysis (for handover) , geo-localization (for emergency and enhanced services), user profiles …TBC.

6.2.6. Media Gateway

A Media Gateway is the component of a switch that deals with transport of the payload data. It provides an interface between a PSTN and/or ISDN networks and a packet voice network. It encodes circuit-switched voice calls and repackages them into IP packets (or vice versa).

6.3. Protocol stack reference model

6.3.1. User and control voice planes

The following figure depicts both the user voice and call control planes. It does not describe the WLAN authentication plane.

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Figure 1: User and call control voice planes

In the figure, the ETH L2 (layer 2) represents Either IEEE 802.3 MAC and IEEE 802.2 LLC Or Ethernet II MAC.

The payload bridging function (L2 bridging) inside the AP shall be compliant as described in section 2.6 of the document [1]. The 802.2 header shall include the LLC header and the SNAP header based on the RFC1042 (see Figure 2: IPEncapsulation frames format).

Editor’s question: needed clarification from Wi-Fi alliance about bridging with 802.3 or only with Ethernet II?

6.3.2. Authentication plane

TBD (depends on the authentication chosen method)

7. High level Requirements

The main identified requirements apply to:- WLAN in Corporate Network- Initialization

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TIA/EIA/TSB-146)- QoS, Bandwidth management and Performances- Security, Encryption and Performances- Mobility- Management - Emergency calls- Control protocol (H.323, SIP, H.248…)- Acoustic requirements- Tests methodology

The following table lists the requirements for accessing to voice services through WLAN network within a corporate networking environment.

Req #

Definition Comments

1 WLAN in Corporate Network:The radio access network shall be an IEEE 802.11 network and shall be based on the Infrastructure mode (DSS). The ad-hoc mode (IBSS) shall not be supported.

Open point: RTP direct for voice streams?????

The radio access network including WTs and APs shall be compliant to the Wi-Fi Alliance specifications.

WPA2, WME/WSMWMM/WMM-SA, VoWLAN,...

The radio access network including WTs and APs shall operate in multi-mode multi-band environment.The radio access network including WTs and APs shall operate in multi-vendors environment.The overlaid internetwork is based on IPV4 technology.

IPV6 may be added as a requirement in a future release

2 Initialization:The radio access network shall be able to support multiple Voice VLANs per AP.The initialization time for a WT shall be comparable to the time of initialization of wired VoIP phone.

-Scan time (country dependent 802.11d).-Association &

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authentication as fast as possible.

It shall be possible to assign IP address dynamically to APs and WTs by means of DHCP.WT shall support several dynamically configured codec’s. But G.711 and L16-256 are mandatory respectively for narrowband terminals and wideband terminals.

G.723.1, G.729, AMR NB, G.722, G.7.22.1, G.722.2, …are optional.

3 QOS:The Voice quality with a WT shall equal the voice quality of wired VoIP phone.

Even under conditions leading to packet loss, jitter, delay, encryption

The Voice quality for a moving WT shall equal the voice quality of wired VoIP phone when handovers occur.

-Even under condition leading to scanning, re-association, re-authentication, IP mobility.-The L2+/L3 handover time shall be < 50ms.

The level of QoS for a WT shall equal the level of QoS available for a Wired VoIP phone.

-Voice/video activity shall be differentiated and prioritized.-802.11e. WMM/WMM-SA ???

WTs and APs shall offer a bandwidth management mechanism close related to CS capability. WT shall know the APs fulfilling its requirements.

-Association with a WT is perform only if APs/Switches are able to offer needed QoS.-Re-association shall be possible only with APs able to satisfy WT actual bandwidth needs.

4 Security:The authentication scheme needed in the WT shall not compromise handover and QoS performance during re-authentication process between APs.

Voice quality shall not be affected.

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It shall be possible to perform authentication process through WLAN smart card of a WT.AP shall support simultaneously encrypted and unencrypted voice communications from different WTsIt shall be possible to encrypt the voice traffic which is transmitted over the radio link

WT Real time performance shall not be affected.

It shall be possible not to use WPA2 for encryption

End-to-End encryption between WT and CS for both signaling and/or voice stream

5 Mobility:Handover time for WT shall equal the handover time of legacy wireless voice terminals.

-DECT, PWT-Low speed mobility

Criteria for Handover decision. One or several of : RSSI, RCPI, SNR, PSNI, RCPI, ED, Load

Handover may be initiated either by the WT or by a Mobility Agent (MA)

Impacts on Handover?

A MA can handle APs in different IP subnets

Impacts on Handover?

Handover may happen between a WT associated with an AP controlled by 1 MA and an AP controlled by another MA.

Exchange of information between MAs for Handover

WT shall know the APs able to support short handover timing.

This has to be related with QoS and security requirements.

WT shall reduce scanning time for a re-association

Scanning is performed even if the WT is already associated.

WT shall support “make before break” to reduce handover timing.

Need figures for “break before make” in L3 configuration.

WT shall take into account L3 handover Break/free links/resources

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with the old association.MAs shall provide candidate APs list In a MAs-based handover

scenario.6 Management:

WTs, APs, MAs shall support internationalization

National regulation, Transmit power Control, 802.11d

WTs, APs, MAs shall be managed from a central pointWTs, APs, MAs shall provide a Software/firmware version upgrade utility

Via FTP, TFTP

The WT shall support the power-save mode as defined by the IEEE 802.11e

What about WiFi CE spec?

Standby time of WT shall equal the standby time of legacy wireless voice terminals.

DECT, PWT,…

Incoming communications shall not be lost when WT is in a standby mode.

APs should manage frames for a leaving standby mode WT.A standby WT shall get ready to resume at any time.

WLAN Information shall be available via WT

Signal strength, SSID List, Mac Address, IP address, Encryption Scheme, VLAN assignment, elapsed time for handover...

WTs, APs, MAs shall maintain a keep-alive mechanism

Facilitate report activity

7 Emergency Calls:WTs, APs, wireless switches and Call Servers must handle emergency call traffic with high priority.

Even in congested networks.

WTs, APs, wireless switches and Call Servers must maintain emergency calls for a mobile user.

Even in handover situation.

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WTs and APs must maintain voice communication even after an hang-up WLAN must provide indoor geo-localization information.

Signal strength,… to perform localization operation, with a precision <2m

8 Control protocols:WT shall support IP standard (SIP or H.323, H.248) protocolsWT shall be able to handle DTMF via IP signaling protocols and/or via dedicated RTP protocols RFC2833, RFC2198 and/or In-band.

9 Acoustic:10 Tests: See WPP

8. Requirements and Procedures

Editor’s comment: this section will describe the requirements and if needed the MSC (message sequence chart) involving the network equipments (WT, AP, switch, MA, CS) that are not already depicted in other existing standards. These requirements will cover both lower layers (802.11) and upper layers and close interaction between them. For example in a” H.323 profile”, the security requirements will be addressed at several levels (802.11, IP, H.235).

8.1. Initialization

8.2. QoS managementIn Enterprise, the wide deployment of Voice over WLAN will be possible only if WLAN infrastructure offers QoS. This QoS must enable prioritization of the voice traffic, must prevent new voice calls to interrupt existing ones and must preserve good voice quality for existing calls. QoS enables also support for Voice over IP technologies without compromises and must take care of handover situation.

The QoS mechanism shall not preclude interoperability issues by providing multiple solutions often difficult to implement or incompatible.

A solution is to adopt recommendations and standards coming from both IEEE 802.11e and WFA WMM. The QoS is solved by using WMM (see WFA test plan), Unscheduled APSD and TSPEC for admission control.

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TIA/EIA/TSB-146)WMM is based on IEEE 802.11a, 11b or 11g with WPA and the system shall comply with the EDCA protocol as defined in [11-03-0504-07-000e-WMMredlined09Mar.doc]

Editor’s Remark: WME and WSM have been renamed in WMM and WMM-SA.Editor’s comment: should we support multiple QoS mechanisms?

8.2.1. Bandwidth management

8.3. Security

8.3.1. WPA2/SA

8.3.2. Authentication

Editor’s comment: The IEEE 802.11 does not specify which authentication layer(s) to use on top of EAP. This section has to do it among EAP-TLS, EAP-MD5, IAKERB…. WFA has specified EAP-TLS; investigation needed to see if it is suitable for a WT in term of power processing and of mobility (latency during re-authentication).

Editor’s comment: Some Access Points may support a “mixed mode”, which supports both clients running Wi-Fi Protected Access and clients running original WEP security. But all the WT shall support the WPA.

Editor’s comment: An alternative authentication of scheme using a pre-shared key (PSK) methodology is included in the 802.11i specification, for homes and small businesses that do not have the resources to deploy an 802.1X infrastructure. Should this scheme be supported?

8.3.3. Key management

8.3.4. Ciphering

8.3.5. Re-authentication

8.3.6. End-to-End Security

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TIA/EIA/TSB-146)8.4. Mobility

8.4.1. L2 handover

8.4.2. L3 handover

8.5. Management

8.6. Emergency callsOne major requirement is that emergency calls must always be taken into account whatever the circumstances (congestion, handover…).But an assumption taken here is that all VoWLAN activity is based on a QoS enabled L2 network.

Editor’s comment: All the material below is for discussion purposes.

8.6.1. Congestion

Have a specific button (or soft-key) on WTs for helping earliest detection of emergency call. This will allow the WTs to know that he must enter in an emergency state.

Use “en bloc” digit sending in order to avoid several signaling to be sent in an already overloaded network. This will allow the WTs to know that must enter in an emergency state.

Allow several dial rules to be used by the user for emergency calls (0-911, 911, 9-911…)

Define specific SSID reserved for emergency call with enough bandwidth (the WT must know that is handling an emergency call and must use this SSID).

…

Moreover emergency call handling must be managed at the best in the infrastructure with the possible potential impacts:

Add specific information in 802.11 frames (proprietary/standard) to differentiate emergency call in L2 network.

Add specific queue reserved for emergency traffic (with higher priority than voice).

Reserve bandwidth within APs and wireless switches in order to accept emergency call.

Allow Re-Configuration of AP by the CS on emergency call detection leading to drop non-emergency voice calls.

...

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TIA/EIA/TSB-146)Editor’s Remark: A comprehensive solution may include one or more items described above.

8.6.2. Handover

When engaged in an emergency call a mobile user must be sure that the communication will not be dropped because of AP changes. System must preserve QoS and bandwidth for all voice traffic and subsequent signaling messages.

8.6.3. Miscellaneous

When a user dial an emergency number (911,112…) a message like “SOS call” should be displayed on the screen.

When a user dials an emergency number, the call must be taken into account within a fair amount of time (X seconds).

Location information will be provided by one of the mechanisms described in TSB-146.

Call will not be released even if the user hangs up.

Emergency call can happen with stimuli terminals or rather clever units running H.323 or SIP protocols. For SIP terminals IETF’s documents: “draft-schulzrinne-sipping-emergency-arch” and “draft-schulzrinne-sipping-emergency-req” provides valuable information. H.323 terminals have also the ability to indicate the priority of a call (H.460.4) and with H.460.9, they can report QoS information. More generally ITU-T SG16’s H.460.x series will supply standard materials for emergency calls.

For bi-mode terminals (i.e.: Wi-Fi and GSM/UMTS) emergency call can be handled by enterprise or by operators depending on chosen media. This kind of terminals can use 1 media first and after unsuccessful tries, fall back to other.

Any intelligent terminal should be able to use an emergency URL (i.e.: sip:sos@example.com) even if it is not registered in the enterprise logical VoWLAN infrastructure.

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TIA/EIA/TSB-146)8.7. Control protocols

8.7.1. SIP

8.7.2. H.323

8.7.3. H.248

8.8. Acoustic

The overall system should be conformant to IUT-T recommendation: P.1010 “fundamental voice transmission objectives for VoIP terminals and gateways” -July 2004 and Recommendation P.313 “Transmission characteristics for cordless and mobile digital terminals” - April 2004.

8.9. Test methodology

9. Options for the corporate environment within the WFA specifications

9.1. Introduction

The 802.11 standard specifies some mandatory and optional features. For WLAN interoperability, the WFA defines the test specifications describing also which 802.11 optional features become mandatory. The TIA approach for the VoWLAN interoperability is to be compliant with the WFA specifications with needed supported features for VoIP aspect, meaning that mandatory Wi-Fi functions are also mandatory functions for TIA.

Thus, this section lists the Wi-Fi options, as defined in document [1] as ‘not mandatory function’ and indicates if these options should be supported or not in the TIA specifications.

Editor’s comment: To be checked if 802.11 optional features not addressed by WFA need to be added in this table.

9.2. PHY options

9.3. MAC options

The table lists the options and indicates functional (F) or performance (P) issue.

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Nr Wi-Fi Optional capabilities

Chapter TIA mandatory (M) or Optional (O)

P/F Comments

AP WTStation Power save modeGeneration of RTSFragmented transmissionPCF support… (*)

(*): Others support capabilities to add (EDCF, HCF, …)

10.Appendix – Informative

10.1. Encapsulation Frame format

The following picture depicts how an IP packet is encapsulated in a 802.11 frame.

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TIA/EIA/TSB-146)Figure 2: IP Encapsulation frames format

Regarding the authentication procedures, the 802.1X packets encapsulation within 802.11 frames is described in the document [7].