A Framework for Integrated Management
of Mobile-Stations Over-the-Air
P. Oommen
Nokia Research Center
6000 Connection Dr.
Irving, TX 75039
USA
paul.oommen@nokia.com
Abstract
Mobile devices are in the process of evolution. The capabilities that 3G promises
open up a number of new possibilities for mobile communications. Future mobile
devices will be communication devices with computational capabilities supporting
wide variety of applications that require high data rates, capacity and multimedia
capabilities. To support high quality services and improve the satisfaction of the
users, over the air management of parameters and resources in a mobile station (MS)
would be useful. There are emerging standards and technologies to bring
manageability to a mobile hand-held device. This paper discusses the issues in over
the air management and introduces a framework for over the air management of
CDMA MSs leveraging the Wireless Application Protocol (WAP).
Keywords
CDMA, Mobile Station, Integrated Management, Over the Air Management, Service
Provisioning, Diagnostics, Software Download, Wireless Application Protocol.
1. Introduction
A framework for managing a mobile device over the air would be beneficial both for
the mobile user and the wireless service provider. Over the air handset management
(OTAHM) includes, but not limited to, the functions of handset provisioning,
parameter administration, software downloading, etc. This enables mobile user to
choose a service provider and provision the service, subscribe to new services and
download software modules. For mobile users this implies improved services,
flexibility, and personalized choice. For carriers, this will enable a new level of
customer care by providing customized and value added services, detecting and
fixing faults. Customer care centers will be able to monitor selected parameters in a
MS, run tests and diagnose faults over the air. OTAHM framework will also enable
multi-mode/ multi-band 3G MS and a true software reconfigurable "universal
handset".
0-7803-6719-7/01/$10.00 (c) 2001 IEEE
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Section 2 identifies the issues in managing a mobile device. In section 3 various
over the air management functions are described briefly. A brief introduction to
Wireless Application Protocol is given in section 4. In section 5, a framework for
over the air management of mobile devices is introduced. Emerging technologies and
standardization activities related to OTAHM are identified in section 6.
2. Considerations
Management requirements for a mobile device differs from that of traditional agentmanager based model for managing fixed devices in an Internet based management
framework. A mobile device is limited in its computational resources. Furthermore,
the user can move, requiring location specific update of management information
and changing network topology. Managing mobile devices produced by wide range
of vendors in heterogeneous wireless network environments is a challenging
problem.
In the traditional model, a management operation begins with the server sending a
request to an agent in the managed device. The agent provides access to the
resources through appropriate instrumentation. In the case of managing mobile
devices, the agent or management entity in the mobile device should also be able to
initiate some management operations. An example is updating of Preferred User
Zone List (PUZL) [1] in a CDMA device. A solution for managing mobile devices
should make effective use of computational resources in the mobile device and
leverage protocols already implemented in the device. One such protocol is the
Wireless Application Protocol (WAP), which is the protocol of choice for 3G
handsets.
A bearer independent protocol like WAP allows management of mobile devices
using WAP over Short Message Service (SMS) or over other lower layer protocols
mentioned in the specification [5]. Managing devices using WAP over SMS requires
support for two way SMS: mobile originated SMS (MO-SMS) and mobile
terminated SMS (MT-SMS). Nearly all installed base of CDMA and GSM mobile
phones support MT-SMS, and at the beginning of 1999, approximately 75% of GSM
handsets supported MO-SMS [12]. In the case of US CDMA, IS-95 and cdma2000,
deployment of two-way SMS began only in year 2000.
3. Mobile Management Functions
Basic OTAHM functions can be classified as, but not limited to, Over the Air
Service Provisioning (OTASP), Over the Air Parameter Administration (OTAPA),
Over the Air Software Download (OTASD) and Over the Air Mobile Diagnostics
(OTAMD).
OTASP is subscriber initiated first time programming of a MS. In an IS-95
CDMA [1] handset this involves programming of Number Assignment Modules
(NAMs), data options, operating parameters, generation and verification of
Authentication Key (A Key), programming of Preferred Roaming Lists (PRL) [1],
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etc. OTASP enables a new customer to subscribe to a service over the air without
the intervention of a customer service assistant. MS must be bootstrapped with
information about a trusted provisioning server before it can be provisioned.
OTAPA is network initiated updating of parameters, possibly with user knowledge,
in a previously provisioned MS over the air. This can be updating of data options,
operating parameters, PRLs, network topology changes while roaming etc.. Handset
must be provisioned before it can be updated using OTAPA methods.
OTASD involves techniques for downloading software modules over the air and
managing software modules in a handset. With the development of multiple nonconverging bearer technologies, the trend is towards an adaptive multi-mode
handset, which can switch to the desired bearer, hardware and software configuration
on demand [2] [3]. Also a handset user can subscribe to different value added
services, which requires downloading special software modules. Such a multi-mode,
multi-service handset requires downloading software modules. This can be end-user
application, physical layer processing algorithms, communication protocols, etc. For
example a handset can download appropriate software modules and switch from
CDMA mode to GSM mode.
Capability to diagnose a handset over the air is a desirable feature as it helps in
isolating faults and helps in network directed improvement in Quality of Service
(QoS). OTAMD involves requesting statistics and performing diagnostic tests over
the air. OTAMD helps in fixing abnormalities and network directed enhancement of
QoS.
4. Wireless Application Protocol- A Brief Introduction
WAP [5] is an application environment and set of communication protocols for
mobile devices designed to enable manufacturer-, vendor-, and technologyindependent access to the Internet and Intranet based information and advanced
telephony services. The WAP specifications define a set of protocols in application,
session, transaction, security, and transport layers, which enable operators,
manufacturers, and applications providers to meet the challenges in wireless crossplatform, distributed computing.
WAP is very similar to HTTP/HTML except that the protocol is optimized for
mobile devices with limitations of, low-memory, low-display and low-bandwidth
capabilities.
A WAP request is routed through a WAP gateway, which acts as an intermediary
between the “bearer” (GSM, CDMA, TDMA, etc). The gateway then decodes the
request, retrieves contents or calls CGI scripts, Java servlets, or some programs in
the content server. The retrieved content can be in Wireless Markup Language
(WML) [6] form or HTML form. HTML contents are translated to WML before it is
encoded at the WAP gateway for return to the client. WML is a markup language
based on XML. Once the WML content has been encoded, the gateway then sends
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the encoded content, which is in binary form, to the client for display and/or
processing.
MS
Client
WAP
Gateway
Content
Server
Request
Request (encoded)
Scripts/
Programs
Decode/
Encode
User
Agent
Response (encoded)
Response (content)
Content
Figure 1: WAP Computing Model.
5. Framework for Integrated MS Management based on WAP
In this section a new method for OTAHM [4] based on WAP [5] is presented. The
proposed approach is backward compatible with existing standards for managing a
CDMA MS.
5.1 Network Architecture
The proposed method is based on WAP, which has become the de facto global
industry standard for providing data to a WAP enabled MS. WAP provides a
uniform technology platform for delivering wireless data, and telephony services to
mobile devices.
OTAHM is achieved by exchanging management messages between an OTAHM
server in the network and an entity in the MS. The OTAHM Server sends and
receives management messages and data via the WAP Server. This can be service
indication containing messages and content URLs or management data embedded in
a WML [6] document. WML is designed for specifying content and user interface
for WAP enabled mobile devices. The OTAHM entity in the MS processes these
messages and initiates appropriate management action. In addition, the OTAHM
entity interfaces with the signaling layer, transport layer and managed objects in the
MS as shown in Figure 2.
Interfacing to the transport layer and signaling layer allows backward compatibility
since there are existing methods for managing devices over the air using transport
layer [10] and signaling layer protocols [1]. This allows seamless managing of a MS
moving from one serving wireless network to another.
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User Interface
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MS
User Interaction
OTAHM
Entity
OTAHM Interface
Managed Objects
CDMA Signaling
Layer
IS-683-A Interface/
Signaling
WAP
Gateway
Wireless
Network
IP Network
OTAHM
Server
Management
Data
Figure 2: OTAHM - Network Architecture.
The OTAHM Server sits in the IP network and interfaces with the wireless
network. This allows managing handsets using signaling protocols in systems that
support IS-683 [1] based initial provisioning and configuration management.
5.2 OTAHM Entity in the MS
The basic capability of the OTAHM entity in the MS is to execute WML and WML
Script. The agent receives management messages from the OTAHM server and
invokes the appropriate interface for completing the management function specified
in the message or indication from the server.
After completion of a management function, the agent sends responses and
acknowledgements back to the OTAHM Server via the WAP Gateway. For MS
initiated functions, the agent can send a request to the OTAHM server. In this case,
the agent creates the messages and performs the content encoding and sends it as a
WML document.
The agent uses the Mobile Management Interface (MMI) for management-related
functions. The agent needs the following three interfaces.
•
•
•
Signaling layer interface.
Interface to managed objects.
Interface to transport layer.
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Managed Objects
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MS
MO Interface
OTAHM Entity
Agent
WSP
IP based
Protocols
Signaling
Protocols
WTP
TL Interface
WTLS
SL Interface
WDP/ UDP
.
.
CDMA Bearer
Figure 3: OTAHM Entity in the MS.
These interfaces are defined in the following section
5.3 Mobile Management Interfaces
OTAHM agent has interfaces to the signaling layer, transport layer and the managed
objects. This allows integrated management and backward compatibility with
existing methods as described below.
An interface to the signaling layer helps in achieving backward compatibly with
existing TIA/ EIA-IS-683-A [1] standards for OTASP/ OTAPA in a CDMA
Network. Because of the heterogeneous nature of wireless network it is possible that
some wireless networks supports only messaging based on signaling protocol. In
such networks the signaling protocol based OTAHM messages are translated to
WML at the signaling layer interface (SL Interface). SL Interface can also be used
for software downloading in a CDMA network using data burst messages.
Accessing managed objects is necessary for updating parameters in the case of
OTAPA and retrieving statistics for diagnosing a MS over the air. For OTAPA and
OTAMD, the agent calls the appropriate managed object interface (MO Interface)
function.
A transport layer interface (TL Interface) is essential to use existing TCP/IP based
management protocols. In certain cases of OTAHM, as in downloading software
modules or uploading virus control software updates, existing TCP/IP based
protocols like TFTP can be used.
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5.4 Representation of MS Managed Objects
Managed objects is a well known terminology in Network Management and we do
not describe it here in detail. Briefly, a managed object is an external management
view upon a resource in the MS to be managed. It mainly consists of attributes that
represent properties of the software and hardware components such as version
number, statistical error counters, control parameters, configuration parameters like
NAM, PRL, PUZL, management operations such as reset, suspend, resume, and
asynchronous events to be reported.
The OTAHM server also keeps a copy of the managed objects for configuration
management of each provisioned MS in a database. The managed object database
for a MS is created at the time the MS is provisioned. Before updating a managed
object in the MS, the OTAHM server queries the same object in the local database to
determine the increment. This helps in incremental update of parameters in the MS,
thus reducing management related over the air traffic.
We define the following scheme for uniquely identifying managed objects in a
CDMA MS. Since a wireless service provider may support several makes of MS and
several models of each make, the following hierarchical scheme uniquely identifies a
managed object.
Enterprise.Model.UniqueMSID.ObjectID
In URL form the object identifier can be represented as ,
http://TrustedDomain/Enterprise/Model/UniqueMSID/ObjectID
Enterprise.Model.UniqueMSID.ObjectID
Enterprise.ObjectID
Enterprise.Model.ObjectID
Figure 4: Organization of Managed Objects.
The Trusted Domain is the domain name of OTAHM server. For CDMA handheld
devices, UniqueMSID can be the ESN. ObjectID is the indexed identifier of the
object. Following diagram shows how various managed objects are organized.
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A format similar to SNMP SMI can be used to represent managed objects. For
managed objects in a mobile device, additional fields are needed in the definition of
objects. For example, a "roaming" field can be used to indicate if the object can be
managed when the user is roaming.
6. Related Technologies and Standardization Activities
According to a 1999 industry survey [7], eight of twelve carriers voted for OTAHM
as an important feature for their CDMA data deployment with an average rating of 9
on a scale from 1 (least important) to 10 (most important). The respondents to this
survey gave OTASP/ OTAPA a rating of 9, OTASD a rating of 7, and OTAMD a
rating of 5 for the year 2000. Various existing and emerging standards and
specifications in the areas of OTAHM are discussed in this section.
6.1 TIA/EIA Standards
Prior to the deployment of data capable networks and handsets with data support, the
telecommunications industry created standards for OTASP and OTAPA in the form
of TIA/EIA-IS-683-A [1] and TIA/ EIA-IS-725-A [8] using existing network
elements and Short Message Service (SMS). Because of the special purpose nature
of the network elements required for providing IS-683-A based OTASP and
OTAPA, carriers employed proprietary methods.
At present OTASP and OTAPA of IS-95 CDMA handsets are performed using the
procedures and architecture described in TIA/EIA-IS-683-A and TIA/EIA-IS-725-A.
IS-683 describes the over the air messaging protocol and procedures for provisioning
a handset in analog mode and CDMA mode operation [1]. The later specifies the
Over the Air-Function (OTAF) network entity that is responsible for processing
OTASP communication between the Customer Service Center (CSC) and the MS via
the Mobile Switching Center (MSC) [8].
6.2 WAP Forum Specifications
The WAP forum working group on provisioning is currently involved in developing
a network independent method for provisioning WAP related parameters in a handset
[9]. The WAP provisioning mechanism leverages the WAP technology whenever
possible. This includes use of the WAP stack in the handset and WAP network
entities. The provisioning architecture attempts to generalize the mechanisms used
by different network types so that the network specific part is isolated to the
bootstrap phase. Bootstrapping is done to an unprovisioned handset to update
information about a trusted provisioning server.
6.3 IP Based Handset Configuration Management
There are two different methods for configuration management (OTASP and
OTAPA) of CDMA mobile handsets. There is the RFC2604 which is configuration
management using Application Configuration Access Protocol (ACAP) [10] and the
specification of CDMA Development Group (CDG) which is under development
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[11]. CDG is working on a method for OTASP and OTAPA leveraging existing
SMS, IS-707-A CSD [12] and packet data network infrastructure to come up with a
cost-effective alternative for IS-683-A based OTASP and OTAPA. The proposed
method is based on the Internet Protocol (IP) and supports IS-683-A features. It
leverages HTTP/ MIME standard for exchanging OTASP and OTAPA related
management data.
7. Conclusion and Future Work
In this paper, the concept of MS as a manageable device was introduced. A
framework for OTAHM was proposed. The integrated approach is flexible to add
new management functions and allows backward compatibility with existing
standards for OTAHM.
Much work remains to be done in the area of OTAHM. Security management to
restrict access to certain parameters in the MS, updating changing topology of the
wireless network when the MS is roaming, management of mobile devices in
enterprise systems, and reducing latency time in software downloading are some of
them. Further, the approach followed in the paper can be extended to a generalized
XML based method for OTAHM.
References
[1] TIA/EIA-IS-683-A, "Over-the-Air Parameter Administration of Mobile Systems
in Spread Spectrum Systems", Published in May 1998.
[2] C. Noblet, A.H. Aghvami , "Assessing the Over the Air Software Download for
Reconfigurable Terminal", IEE Colloquium on Personal Communications in the 21st
Century, 1998.
[3] F. Riera-Palou, C. Chaikalis, J.M. Noras, "Reconfigurable Mobile Terminal
Requirements for Third Generation Applications", IEE Colloquium on UMTS
Terminals and Software Radio, 1999.
[4] P. Oommen, Nokia Internal Report, May 2000.
[5] "Wireless Application Protocol Architecture Specifications", WAP Forum, April
1998.
[6] "Wireless Markup Language Specification", WAP Forum, November 1999CDG
IOTA OTASP/ OTAPA Ad Hoc, "Service Provider Survey of CDG-IOTA Handset
Configuration Management", February 1999.
[7] TIA/EIA-IS-725-A, "Cellular Radio-telecommunications Intersystem Operations
- Over-the-Air Service Provisioning (OTASP) & Parameter Administration
(OTAPA)", July 1997.
[8] WAP Forum, "WAP Provisioning Architecture Overview", February 2000.
[9] R. Gellens. " Wireless Device Configuration (OTASP/OTAPA) via ACAP" ,
RFC 2604, June 1999.
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[10] CDG IOTA OTASP/ OTAPA Ad Hoc, "IP based Over the Air Handset
Configuration Management: Stage 2 and 3", May, 2000.
[11] TIA/EIA/IS-707-A, "Data Services Standard for Wideband Spread Spectrum
Cellular Systems", April 1998.
[12] S. Buckingham, "An Introduction to the Short Message Service", GSM World,
Issued July 2000.
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