| 리포트 | 기술문서 | 테크-블로그 | 글로벌 블로그 | 원샷 갤러리 | 통신 방송 통계  | 한국 ICT 기업 총람 |

제품 검색

| 네트워크/통신 뉴스 | 기술자료실 | 자유게시판 |  
 
 
섹션 5G 4G LTE C-RAN/Fronthaul Gigabit Internet IPTV/UHD IoT SDN/NFV Wi-Fi Video Streaming KT SK Telecom LG U+ OTT Network Protocol CDN YouTube Data Center
 
스폰서채널 |

 

  스폰서채널 서비스란?
Seamless Integration of Mobile WiMAX in 3GPP Networks
October 01, 2008 | By Intel
코멘트 (0)
4
Thank you for visiting Netmanias! Please leave your comment if you have a question or suggestion.
Transcript
WIMAX: A TECHNOLOGY UPDATE


Seamless Integration of
Mobile WiMAX in 3GPP Networks

Pouya Taaghol, Intel Corp
Apostolis K. Salkintzis, Motorola
Jay Iyer, Cisco Systems

ABSTRACT

As the wireless industry makes its way to the
next generation of mobile systems, it is important
to engineer solutions that enable seamless
integration of emerging 4G access technologies
within the currently deployed and/or evolved
2G/3G infrastructures. In this article we address
a specific case of such a seamless integration,
that of mobile WiMAX in evolved 3GPP networks.
In this context we investigate the architecture
and the key procedures that enable this
integration, and we also introduce a novel hand-
over mechanism that enables seamless mobility
between mobile WiMAX and legacy 3GPP
access, such as UTRAN or GERAN. The core
characteristic of this novel handover mechanism
is that mobile terminals do not need to support
simultaneous transmission on both WiMAX and
3GPP accesses; therefore, it mitigates the RF
coexistence issues that exist otherwise and
improves handover performance. In addition, we
provide a brief overview of mobile WiMAX and
the evolved 3GPP network technologies, and we
set the appropriate background material before
presenting our proposed handover mechanism.
Our main conclusion is that integrating mobile
WiMAX in evolved 3GPP networks is a compelling
approach for providing wireless broadband
services, and mobility across WiMAX and
3GPP access can become seamless and efficient
with no need for mobile terminals to support
simultaneous transmission on both types of
access.

INTRODUCTION

Broadband Internet applications are contentiously
driving the demand for higher data rates with
more cost-effective transport mechanisms. The
wireless industry is in transition toward cost-
effective broadband mobility in order to provide
service transparency with that of wired broadband
(e.g., digital subscriber line [xDSL] or
cable). Unlink the migration from the second
gneration (2G) to the third (3G), the transition
to the fourth generation (4G) is more than a
simple technology upgrade, and requires signifi


cant changes to backhauls, radio sites, core networks,
network management, services paradigm,
and mobile device distribution model. Thus, the
migration to 4G should be regarded as a major
economic transformation.

The wireless industry is migrating toward
orthogonal frequency-division multiple access
(OFDMA)-based air interfaces for beyond 3G
(Long-Term Evolution [LTE], Ultra Mobile
Broadband [UMB], or WiMAX), which are not
backward compatible with 2G, 2.5G, or 3G technologies.
Figure 1 shows the evolution of air
interfaces and their backward compatibility relationship
with the previous technologies. As
shown, the 3GPP2’s UMB and 3GPP’s LTE air
interface technologies are not evolutions of a
legacy radio technology in the corresponding
family of standards. Additionally, legacy core
networks have been optimized for circuit voice
and slow data rates. Hence, a new flat all-IP network
is required to process very many large and
small packets per second. Furthermore, this
would mean that in most cases new core network
infrastructure is required to cope with the significant
increase in broadband traffic volume; thus,
mere software upgrade of existing core network
nodes would be undesirable and/or impossible
for this migration.

Regardless of backward compatibility, however,
it is essential that the new wireless technologies
reuse the existing networks and radio
resources as well as provide interworking with
legacy systems. Like any other wireless technology,
4G would also be deployed in phases, and it
becomes important to fill the 4G coverage gaps
with legacy 2G/3G access technologies to provide
a ubiquitous and seamless user experience.
The integration of emerging 4G access technologies
(e.g., mobile WiMAX) with existing 2G/3G
accesses (e.g., code-division multiple access
[CDMA], General Packet Radio Service
[GPRS]/Enhanced Data for GSM Evolution
[EDGE], Universal Mobile Telecommunications
System [UMTS], High-Speed Packet Access
[HSPA]) into a common system architecture can
be the first step toward the migration to mobile
broadband networks and provide the users with
the “best connection” at any place, anytime.

0163-6804/08/$25.00 ⓒ 2008 IEEE IEEE Communications Magazine . October 2008


nFigure 1. Evolution and backward compatibility of air interface technologies.
Improved spectral efficiency
WiBRO
802.11n
HSPA+ UMB
IS-95C
cdma2000 W-CDMA
FDD
W-CDMA
TDD
TD-SCDMA
LCR-TDD
3G
1xEV-DO
release 0
HSCSD GPRS/
EDGE iMode
1xEV-DO
release A
1xEV-DO
release B
HSDPA
FDD-TDD
HSUPA
FDD-TDD
Beyond
3G
2.5G
2G
LTE
E-UTRA
802.11g
802.11a
802.11b
802.16d
fixed
WiMAX
802.16e
mobile
WiMAX
802.16m
mobile
WiMAX-2
IS-95B
cdma
IS-95A
CDMA
S-136
TDMAGSM PDC
Improved spectral efficiency
WiBRO
802.11n
HSPA+ UMB
IS-95C
cdma2000 W-CDMA
FDD
W-CDMA
TDD
TD-SCDMA
LCR-TDD
3G
1xEV-DO
release 0
HSCSD GPRS/
EDGE iMode
1xEV-DO
release A
1xEV-DO
release B
HSDPA
FDD-TDD
HSUPA
FDD-TDD
Beyond
3G
2.5G
2G
LTE
E-UTRA
802.11g
802.11a
802.11b
802.16d
fixed
WiMAX
802.16e
mobile
WiMAX
802.16m
mobile
WiMAX-2
IS-95B
cdma
IS-95A
CDMA
S-136
TDMAGSM PDC
One of the

challenges associated
with the integration
of mobile WiMAX
and 3GPP accesses
arises from their
differences in terms
of AAA procedures,
QoS mechanisms
and mobility
protocols.

Such integration allows operators to reuse existing
backend systems, simplifies operation aspects
(network management, customer acquisition,
converged billing), speeds up network deployment,
and enables access-independent services
and seamless intertechnology handover. However,
such integration requires addressing all the
interoperability issues that emerge when different
access technologies are combined, such as
the provision of a common authentication,
authorization, and accounting (AAA) scheme,
end-to-end quality of service (QoS), and a vertical
mobility management mechanism.

In this article we address the technical issues
around the integration of 4G access technologies
with existing 2G/3G networks, and we focus in
particular on an interesting use case: the integration
of mobile WiMAX within 3GPP networks.
This integration is facilitated by the evolved
packet network architecture (discussed later),
which has recently been standardized by 3GPP
in the context of Release 8 specifications (TS
23.401, TS 23.402). Our goal is twofold. First, we
describe and explain the key issues that emerge
from our effort to integrate mobile WiMAX in a
mobile network architecture that must also support
legacy 3GPP radio accesses (Global System
for Mobile Communication [GSM], UMTS,
EDGE, HSPA) and provide seamless mobility
across all of them. Second, we discuss the solutions
that enable us to attach to and move seamlessly
within the integrated system.

The main requirement for achieving seamless
integration of WiMAX and 3GPP access networks
is to minimize handover interruption and
preserve the QoS as the mobile device moves
between mobile WiMAX and 3GPP access technologies.
The objective is to make the transition
from one access network to another as transparent
as possible to the user (i.e., to offer a seamless
mobility experience). With seamless mobility,
users may exploit both access technologies to
best meet their charging and QoS requirements

(e.g., by automatically selecting the “most appropriate”
access based on some preconfigured
preference settings and operator policies). At
the same time, operators may exploit seamless
mobility in order to offer compelling value-
added services as well as improve their network
capacity and availability of services.

Seamless mobility can be achieved by
enabling mobile terminals to conduct seamless
handovers across mobile WiMAX and 3GPP
access networks, seamlessly transferring and continuing
their ongoing sessions from one access
network to another. A seamless handover is typically
characterized by two performance requirements:


. The handover latency should be no more
than a few hundreds of milliseconds.
. The QoS provided by the source and target
access systems should be nearly identical to
sustain the same communication experience.
These two performance requirements are not
trivial to satisfy when mobile WiMAX and 3GPP
access networks are combined in a single architecture.
In order to offer seamless handover,
several issues need to be addressed. One of
them is how fast the service data flow (i.e., the
stream of data packets associated with an ongoing
service) can be switched from the old path
through the old access network to the new path
through the new access network. Using common
or similar link layer access procedures (e.g.,
authentication, security, and mobility procedures)
in both the old and new access networks
can considerably expedite the handovers. One of
the challenges associated with the integration of
mobile WiMAX and 3GPP accesses arises from
their differences in terms of AAA procedures,
QoS mechanisms, and mobility protocols. Such
challenges and associated solutions are the main
focus of this article.

In this article we address the technical issues
around the integration of 4G access technologies

IEEE Communications Magazine . October 2008


Based on the IEEE
802.16e air
interface, the Mobile
WiMAX provides a
broadband wireless
system that enables
convergence of both
mobile and fixed
broadband
networks. This
convergence is
achieved via a reuse
of a common air-
interface, and flexible
network architecture
to support both
fixed and mobile
networks.

nFigure 2. Mobile WiMAX network architecture.
Home CSN
(if roaming)
CSN
(visited CSN if roaming)
ASN
HA
(optional)
ASN
GW
WiMAX
BS
WiMAX
BS
ASN-GW ASN-GW
Internet/
PDN
IP backhaul Internet/
PDN
IP backhaul
DHCP
server
R5-AAA
R3-AAA
R3-MIP
R4R4
R6
R1
R8
R3-DHCP
AAA
server
AAA
server/proxy
into the existing 2G/3G networks, and we focus
in particular on an interesting use case: the integration
of mobile WiMAX within 3GPP networks.
This integration is facilitated by the
evolved packet network architecture (discussed
later) which has recently been standardized by
3GPP in the context of Rel-8 specifications [1,
2]. Our goal is twofold. First, we describe and
explain the key issues that emerge from our
effort to integrate mobile WiMAX in a mobile
network architecture that must also support
legacy 3GPP radio access (i.e. GSM, UMTS,
EDGE, and HSPA) and provide seamless mobility
across all of them. Second, we present a solution
that enables mobile terminals to attach to
and move seamlessly within the integrated system.
We also address mechanisms to enable
seamless mobility between heterogeneous access
technologies, but we focus specifically on the
integration of mobile WiMAX and 3GPP 2G/3G
access technologies within common network
architecture. We first provide a brief overview of
mobile WiMAX followed by an introduction to
the 3GPP evolved packet system (EPS). We then
proceed to addressing various aspect of mobile
WiMAX interworking with 3GPP, such as integrated
AAA mechanisms, consistent QoS support,
seamless vertical handover, and
interoperator roaming. Finally, we conclude our
discussion by presenting a novel emerging solution
for WiMAX-3GPP interworking and providing
some final thoughts on future steps.

RELATED WORK

In recent years the need to seamlessly integrate
a number of diverse access technologies into a
common network platform has rapidly evolved;
thus, relevant prior work is rather ample. Proposed
solutions deal with various aspects that
influence seamless integration, such as cross-

layer designs in IP-based networks [3], intercellular
handovers [4], context management and
autonomic computing [5], dynamic adaptation of
applications and security issues [6]. To begin
with, [3] proposes a hierarchical mobility management
architecture based on Mobile IPv6. It is
targeted to IP-based networks but can also be
extended to 3GPP networks if Mobile IPv6 is
adopted in the network. In this architecture the
area is divided into smaller and larger regions
where mobility is handled by specific protocols,
reducing mobility-related signaling. The important
aspect of this solution is the consideration
of lower-layer triggers and signaling between
access routers (ARs) that minimizes the delay in
discovering a new AR and allows the network to
make the handover decision based on network
load information, QoS requirements, signal measurements,
and so on. In addition, the authors
analyze a simple way to support communication
over multiple interfaces simultaneously. A different
approach is followed in [4] where wideband
CDMA (WCDMA) and CDMA 2000 network
interoperability is discussed. Issues discussed
focus on more practical problems such as the
efficient translation of messages between the two
networks, handover initiation, hardware implementation,
signaling exchange, and performance.
More specifically, the discovery of the new network
and the transfer of cell information
between the two networks are described at a signal
level. Exchanged signaling also includes measurement
control messages that are used as the
main reason for triggering a handover. Moreover,
only one radio interface is used at a time
to minimize the complexity of the mobile terminal.
Similar to [3], the benefit of having global
knowledge of system conditions (radio strength
measurements, network load information, etc.) is
underscored in [5]. However, in the proposed

IEEE Communications Magazine . October 2008


work, seamless integration is defined as the
means of offering access to data independent of
the type of device or access method. To achieve
this, the system must be able to integrate dissimilar
data under a common language and use this
in order to adapt dynamically to varying system
conditions. The former is quite important as heterogeneous
networks often fail to exchange measurements
or other information in a common
understandable format.

MOBILE WIMAX
SYSTEM OVERVIEW


Based on the IEEE 802.16e air interface [7], the
Mobile WiMAX provides a broadband wireless
system that enables convergence of both mobile
and fixed broadband networks. This convergence
is achieved via a reuse of a common air interface,
and flexible network architecture to support
both fixed and mobile networks. IEEE
802.16e supports scalable OFDMA, which is
essential for supporting multi-access systems
with guaranteed and differentiated QoS capabilities.
The Network Working Group (NWG) of
the WiMAX Forum specifies the system architecture
and detailed protocols and procedures
beyond the air interface standards covered by
IEEE (see [8]). Figure 2 shows the end-to-end
Mobile WiMAX network architecture.

The Mobile WiMAX network consists of the
access services network (ASN) and connectivity
services network (CSN). The core elements in
the ASN are the base station (BS) and ASN
gateway (ASN-GW), connected over an IP cloud.
The functionality across the ASN-GW and BS is
split and signaled via R6. The ASN-GW provides
security anchoring, traffic accounting, and
mobility anchoring (and proxy) for the mobile
station (MS). The Mobile IP home agent (HA)
in the CSN is used as a global mobility anchor,
and is an optional element depending on deployment
choices. In the simplified form (aka Simple
IP), the user traffic bypasses the HA in the CSN.
The user traffic is tunneled as payload between
the BS and the ASN-GW. Mobility between the
ASN-GW and the HA is handled with the Proxy
Mobile IP protocol [9]. A WiMAX BS can
potentially connect to any ASN-GW that it can
reach via IP connectivity (aka flex R6). This flexibility
helps reduce mobility-related signaling in
the network as the same ASN-GW can serve the
user’s active IP session while the user is moving
across several different BSs (e.g., ASN-GW relocation
is rarely required). The R8 interface can
facilitate the context transfer and handover optimization
when the user moves from one BS to
another. Authentication in Mobile WiMAX is
carried out using the EAP framework as shown
in Fig. 3. In the IEEE 802.16 specification [9],
the EAP exchanges are transported between the
MS and BS within Privacy Key Management
(PKMv2) MAC messages.

WiMAX supports two types of authentication:
device-level and user-level. Device authentication
is based on EAP-TLS (see RFC 2716)
and allows an operator to verify compliance of a
device with WiMAX compliance requirements
(this feature empowers an operator to adopt a

MS BS ASN-GW AAA proxy(ies) Home AAA server
(supplicant)(auth relay) (authenticator) (auth server)

EAP methods: EAP-TLS (device auth), EAP-AKA/EAP-TTLS (user auth)
PKMv2 Auth relay protocol AAA protocol (RADIUS/DIAMETER)
EAP

Figure 3. Mobile WiMAX authentication framework.
nFigure 4. Mobile WiMAX PCC architecture.
RxGxR3-PCC-OFCGyR3-MIPAAAserverPCRFPDFAFInternet/
PDNHAGzC-PCEFASNA-PCEFOFCSOCSR3-PCC-OCR3-PCC-OFCR3-PCC-P
retail device model). The user authentication is
based on EAP-TTLS or EAP-AKA (see RFC
4187) and is a way to authenticate the presented
user’s subscription. In the WiMAX network the
authentication is performed using an AAA
framework, with the access protocols of
RADIUS or DIAMETER. The ASN-GW hosts
the AAA client, and the AAA network allows
the home network to authenticate the client. We
assume here that IP address allocation is performed
using Dynamic Host Configuration Protocol
(DHCP), which is true in case mobility is
provided with either Proxy Mobile IP or Simple
IP. When mobility is provided, however, with
client MIP [10], the DHCP protocol is not used.

Mobility in WiMAX is enabled by reference
points R6, R4, R8, and R3 (Fig. 2). Several
mobility scenarios can be supported including
intra-ASN-GW, inter-ASN-GW, and anchored
CSN mobility. The anchored CSN mobility scenario
is an optional deployment option for operators.
As MSs move across BSs, they may be
anchored at a specific ASN-GW, and mobility is
handled within that ASN-GW. There are other
scenarios where clients need to be handed across
ASN-GWs by means of lateral context transfers
via R4.

QoS in mobile WiMAX is handled via multiple
service flows to enable differentiated services.
In order to enable dynamic QoS authorization
and enforcement, the ASN-GW and WiMAX
HA could make use of a policy exchange framework
that is enabled by the policy and charging
control (PCC) architecture shown in Fig. 4.

The policy and charging framework [11] is
designed to allow an access network to connect
to a policy and charging rules function (PCRF)

IEEE Communications Magazine . October 2008


The main
requirement for
achieving seamless
integration of
WiMAX and 3GPP
access networks is to
reuse authentication
infrastructure,
optimize the
handover interruption,
preserve the
QoS as the mobile
device moves
between mobile
WiMAX and 3GPP
access technologies,
and enable inter-
operator roaming.

nFigure 5. Simplified architecture of the 3GPP evolved packet system.
UTRAN
GERAN
WLAN
Evolved packet core
Serving gateway
PDN gateway
Mobility management entity
Enhanced packet data
gateway
Policy and charging rules
function
Home subscriber service
Authentication, authorization,
accounting
EPC:
S-GW:
P-GW:
MME:
ePDG:
PCRF:
HSS:
AAA:
MME
SGSN
AAA/
HSS
S1-MME
S1-U
S11S3
S4
S6aGr
User
equipment
(UE)
Gx
Gxb
Gxc
STa Gxa S2a SWn
S2b
SGiS5S-GW P-GW
ePDG
PCRF
3GPP EPC
E-UTRAN
WiMAX
ASN
Packet data
network(s)
e.g. internet
for the purposes of QoS and charging authorization.
The WiMAX PCC uses the PCRF to
receive the authorization envelope for associated
QoS parameters that are enforced in the ASNGW
by the policy charging enforcement functions
in the ASN-GW (A-PCEF) and/or the HA
(C-PCEF). The A-PCEF may be relocated during
the lifetime of a bearer due to user mobility.
To hide this relocation, a policy decision function
(PDF) in the PCRF is introduced in the
WiMAX PCC architecture.

THE EVOLVED 3GPP NETWORK
ARCHITECTURE


As part of Release 8 of tbe 3GPP specifications,
3GPP has been studying and specifying an
evolved packet system (EPS) under the System
Architecture Evolution (SAE) work item. EPS is
composed of a new radio access network, called
evolved UTRAN (E-UTRAN), and a new all-IP
core network, called evolved packet core (EPC).
The EPC can be considered an evolution of the
legacy GPRS architecture with additional features
to improve performance, support EUTRAN
access, and support integration with
non-3GPP radio technologies such as WLAN
and WiMAX. The latter characteristic is particularly
important. As shown in Figure 5, access to
the EPC is supported not only via 3GPP-specific
access (e.g., E-UTRAN, UTRAN, GERAN) but
also via non-3GPP accesss, such as WLAN and
WiMAX technologies. The EPS specifications
for Release 8 are expected to be finalized by the
end of 2008.

In order to demonstrate later how a mobile
WiMAX access network can seamlessly be integrated
into a 3GPP network, we provide a brief
overview of the evolved 3GPP network architecture
shown in Fig. 5.

As shown in Fig. 5, a number of diverse
access networks, such as WLAN, WiMAX,
GERNAN, UTRAN, and E-UTRAN, are connected
to a common core network (the EPC)
based on IP technology through different interfaces.
All 3GPP-specific access technologies
are connected through the serving gateway (SGW),
while all non-3GPP-specific access technologies
are typically connected through the
packet data network gateway (P-GW) or the
evolved packet data gateway (ePDG), which
provides extra security functionality for untrusted
access technologies (such as legacy WLANs
with no strong built-in security features). The
S-GW acts as a mobility anchor for mobility
within 3GPP-specific access technologies, and
also relay traffic between the legacy serving
GPRS support node (SGSN) accesses and the
PDN gateway (P-GW). In E-UTRAN the SGW
is directly connected to it through the S1
interface, while the SGSN is the intermediate
node when GERAN/UTRAN is used. It is
important to mention that a mobility management
entity (MME) is also incorporated in the
architecture for handling control functions
such as authentication, security, and mobility in
idle mode.

For access to EPC through WLAN and
WiMAX, different data paths are used. A WiMAX
ASN is directly connected to a P-GW through the
S2a interface as trusted access. On the other hand,

IEEE Communications Magazine . October 2008


nFigure 6. Architecture for integrating mobile WiMAX within the 3GPP evolved packet network.
3GPP access
network
Internet/
PDNS-GW P-GW
PCRF
WiMAX
BS
WiMAX
BS
R1
R8
R6
MS/UE
GxGxc
S14 S2a/
R3-MIP
Gr/S6a
Sta/
R3-AAA
WiMAX
access
Gxa/
R3-PCC-P
S5 SGi
EPC
AAA/
HSS
ANDSF
FAF
3GPP access
network
Internet/
PDNS-GW P-GW
PCRF
WiMAX
BS
WiMAX
BS
R1
R8
R6
MS/UE
GxGxc
S14 S2a/
R3-MIP
Gr/S6a
Sta/
R3-AAA
WiMAX
access
Gxa/
R3-PCC-P
S5 SGi
EPC
AAA/
HSS
ANDSF
FAF
AAA client
accounting BEERF PMIP
MAG
R4ASN-GW
IP backhaul
ASN-GW

a WLAN is accessible through the ePDG as a non-
trusted access. All data paths from the access networks
are combined at the P-GW, which
incorporates functionality such as packet filtering,
interception, charging, and IP address allocation,
and routes traffic over SGi to an external packet
data network or to the operator’s packet data network
(for accessing IP services provided by the
operator). Apart from the network entities handling
data traffic, the EPC also contains network
control entities for keeping user subscription information
(home subscriber server . HSS), determining
the identity and privileges of a user and
tracking his/her activities (AAA server), and
enforcing charging and QoS policies through a
PCC architecture [11].

INTEGRATION OF WIMAX WITHIN
THE 3GPP EVOLVED PACKET CORE

The main requirement for achieving seamless
integration of WiMAX and 3GPP access technologies
is to provide an appropriate authentication
infrastructure, optimize the handover
interruption, preserve the QoS as the mobile
device moves between mobile WiMAX and
3GPP access technologies, and enable interoperator
roaming. With seamless mobility, users
may exploit both access technologies to best
meet their charging their charging and QoS
requirements, for example, by automatically
selecting the “most appropriate” access based
on operator policies. At the same time, opera


tors may exploit seamless mobility in order to
offer compelling value-added services as well
as improve their network capacity and availability
of services.

INTERWORKING ARCHITECTURE

The 3GPP Evolved Packet Core exposes generic,
IP-based interfaces towards the non-3GPP access
networks (e.g., mobile WiMAX). Figure 6
demonstrates the logical interfaces connecting
Mobile WiMAX and the 3GPP EPC. We note
that this architecture is largely based on the
specified 3GPP specifications (in particular, [2])
but also features some enhancements we introduce
in this article in order to support the optimized
handover mechanism we propose later.

There are four major logical interface
deployed here:

. 3GPP STa (equivalent of the WiMAX R3AAA
interface [8]): Use for AAA-based
authentication of user equipment (UE) and
enforcement of preconfigured QoS
. 3GPP Gxa (equivalent of WiMAX R3-PCCP
[8]): Used for enforcement of dynamic
QoS and charging rules
. 3GPP S2a (equivalent of WiMAX R3-MIP
[8]): Used for layer 3 mobility and bearer
establishment toward the core network
. 3GPP S14: Used for intertechnology network
discovery and selection, and for facilitating
the optimized WiMAX-3GPP
handover (the latter capability is an extension
of the S14 logical interface specified in
[2]). This interface, as well as the functional
An important aspect
of consideration for
seamless mobility is
how granted QoS is
supported
consistently across
the heterogeneous
access networks.
This involves several
considerations such
as the QoS
mappings and
semantics on the
two access networks
as well as
appropriate resource
allocations.

IEEE Communications Magazine . October 2008


From the user’s
perspective, the
seamless experience
conceals the
heterogeneity of the
system and it is
conceived as an
intelligent system
capable of
manipulating its
available resources
such as to provide
the best service to
the user without
any intervention
from the user.

nFigure 7. WiMAX initial network entry via EPC.
Home network
Local
services/
Internet
Home
services
IP
exchange
SWd
S9
S8
SGi
Visited network
AAA proxy
HSS/
AAA
Home
PCRF
S-GW/
P-GW
P-GW
Visited
PCRF
STa
Gxa
Gx
GxRx Rx
S2a SGi
WiMAX
ASN
elements ANDSF and FAF (shown in Fig.

6) are discussed later, when we explain how

seamless mobility can be achieved between

mobile WiMAX and 3GPP accesses.

The roaming architecture for WiMAX-3GPP
integration is shown in Fig. 7 and supports inter-
operator roaming, which is an important feature
that enables operators to expand coverage
regionally and/or globally. The 3GPP EPC allows
roaming interfaces for exchanging of operator\'s
policies (S9), authentication exchanges (SWd),
routing user traffic to the home operator (S8),
or routing user traffic to the visited network
(this is called local breakout, LBO) for accessing
local services or the Internet. For broadband
Internet traffic it is more cost effective to route
the traffic toward the Internet at the visited network
(LBO) to avoid costly interoperator data
transports. If user traffic is routed to the home
network, the S8 logical interface can support
mobility with either Proxy MIP [9] or the GPRS
Tunneling Protocol (GTP).

The following sections describe how the logical
interfaces shown in Figs. 6 and 7 can be used
to provide seamless integration of WiMAX and
3GPP access technologies.

ACCESS NETWORK DISCOVERY

As the mobile terminal (UE) moves across the
network, it has to discover other radio technologies
available in its vicinity, which could potentially
be preferable to the currently used radio
technology. For example, a mobile terminal using
3GPP 2G or 3G radio access needs to discover
when mobile WiMAX access becomes available
and possibly trigger a handover to mobile
WiMAX if this more preferable to the user and/or
operator, or if the radio signal from its serving
3GPP cell starts to deteriorate significantly.

In the most simplistic case, the UE can discover
neighbor cells with no assistance from the
network by periodically conducting a radio scanning
in the background. Although this is very
simple and does not require any modifications in
the network, the problems are that:

. Battery consumption can increase considerably,
especially when we demand fast discovery.
. The information discovered about the
neighbor cells is only limited.
. The UE needs to have two receivers working
in parallel (one dedicated to scanning,
and another for ongoing communications).
This drives the need for access network discovery
assisted by the network.

The most typical network-assisted discovery
solution used today is to have each cell in the
network broadcast a list of neighbor cells (of the
same or different radio technology) that can
serve as candidates for handover. The same concept
can be applied for neighbor cell discovery
in the integrated WiMAX/3GPP network, provided
that all legacy 2G/3G cells are upgraded in
order to broadcast information about neighbor
WiMAX cells (and vice versa). In addition, when
the mobile device is equipped with a single
receiver, we must make sure that the radio signal
received from neighbor cells is measured
without missing any data from the serving cell.
To ensure this, the serving base station needs to
schedule measurement opportunities to a mobile
device, that is, short time windows in which the
device can safely leave its serving (say) 3GPP
cell and measure neighboring WiMAX radio frequencies.
This solution for neighbor cell discovery
creates a need for intertechnology
measurement scheduling and coordination
(unless all UEs in the network implement dual
receivers).

Alternatively, if there is a need to minimize
the modifications of legacy radio systems, the
neighbor cell information may not be broadcast
on radio channels but rather be retrieved by the
UE from a special functional entity in the network.
Such an entity has been standardized by
3GPP in order to facilitate discovery of WiMAX
cells, and is termed the access network discovery
and selection function (ANDSF) [12]. This function
can be considered a dynamic database that
is queried by mobiles (e.g., with a specific protocol
over IP) whenever they need to discover
neighbor cells of specific or any radio technology
type. It is easy to recognize that such a discovery
solution avoids any impact on the radio systems
and the associated cost of upgrade. The ANDSF
can also be used to provide dynamic operator

IEEE Communications Magazine . October 2008


nFigure 8. Seamless single-radio handover from mobile WiMAX to 3GPP access.
MS/UE
Synchronization and
capability exchange
WiMAX
BS
WiMAX
ASN-GW AAA/HSS P-GW PCRF
EAP authentication
Security handshake
Registration Data path setup
Service flow setup
PCC rule retrival
DHCP discovery
Proxy binding update
Proxy binding acknowledgement
DHCP offer/request
/Ack.
MS/UE
Synchronization and
capability exchange
WiMAX
BS
WiMAX
ASN-GW AAA/HSS P-GW PCRF
EAP authentication
Security handshake
Registration Data path setup
Service flow setup
PCC rule retrival
DHCP discovery
Proxy binding update
Proxy binding acknowledgement
DHCP offer/request
/Ack.
There is no need for
a 3G radio access to
keep track of the
available radio
resources on the
WiMAX side and vice
versa. Of course, this
approach minimizes
the coupling
between the 3GPP
and mobile WiMAX
accesses
(and the associated
upgrade cost).

policies to the mobile devices, which can affect
the devices’ behavior based on some dynamic
operator preferences and rules. In addition, the
ANDSF can provide additional information
about neighbor cells such as QoS capabilities,
service capabilities, charging rate, and a number
of other attributes that cannot be continuously
broadcast on radio channels due to the high
radio capacity demand. The mobile device can
combine this additional information together
with some user-provided data to select the most
preferable radio access technology (WiMAX or
3GPP access) that satisfies both user preferences
and operator policies.

INITIAL NETWORK ENTRY

Initial network entry is a process where the
newly arrived MS/UE is required to access network
services. Figure 8 demonstrates the high-
level procedure for the initial WiMAX network
entry via 3GPP EPC.

In the first step the mobile device is required
to synchronize itself with the BS and exchange
basic capabilities, after which the EAP-AKA
procedure is triggered for authenticating the
identify presented by the MS/UE. As specified in
[13], the user NAI is constructed per RFC 4282
using the International Mobile Subscriber Identify
(IMSI) in the USIM, Mobile Network Code
(MNC), and Mobile Country Code (MCC) as
follows: 0<IMSI>@mnc<MNC>.mcc<MCC>.
3gppnetwork.org, for EAP AKA authentication.
For example, for EAP AKA authentication, if
the IMSI is 234150999999999 (MCC = 234,
MNC = 15), the root NAI then takes the form
0234150999999999@mnc015.mcc234.3gppnetwork.
org. After successful authentication, a
three-way handshake is performed (with the
PKMv2 protocol) between the MS/UE and BS
for exchanging the security keys used over the
air interface. Subsequently, the registration process
begins, which triggers data path establishment
between the BS and the ASN-GW, and

then a service flow is set up according to the
preprovisioned subscriber profile that was downloaded
from the AAA server during the authentication
phase. At this point, the MS/UE assumes
that the layer 2 connection is established, and its
operating system triggers the DHCP procedure
to obtain an IP address. In turn, this triggers a
bearer establishment between the ASN-GW and
the P-GW by means of Proxy MIP (accomplished
with the Proxy Binding Update and Proxy Binding
Update Acknowledge messages). During this
procedure, the PCRF may be contacted to
retrieve policy parameters in the P-GW and
ASN-GW (especially if this initial network
attachment was a result of intertechnology hand-
over).

As can be noted from the procedure above,
the 3GPP EPC enables an MS/UE to attach to
core network resources via WiMAX by means of
an AAA server, a PMIP interface between the
WiMAX ASN-GW and P-GW (called S2a), and,
optionally, a PCC infrastructure for providing
dynamic policy and charging rules to the elements
policing the user data traffic (typically, the
ASN-GW and P-GW).

INTEGRATED QOS

An important issue for providing seamless mobility
is to maintain a specific level of QoS consistently
across the WiMAX and 3GPP radio access
technologies. This involves several considerations
such as the QoS mappings and semantics
on the two access networks as well as appropriate
resource allocations. WiMAX allows creation
of multiple service flows, each with a
specific QoS. This is very similar to the 3GPP
PDP context activation procedure. In addition to
this, classification rules will have to be kept common
across both access networks by coordinating
appropriate rules.

QoS consistency between WiMAX and 3GPP
accesses can be provided via the PCC infrastructure
discussed earlier. Having the PCC

IEEE Communications Magazine . October 2008


The UE uses a source

mobile WiMAX
access system and is
being served by
P-GW. It is assumed
that the mobile
WiMAX network
supports PMIPv6 and
so a PMIPv6 tunnel
has been established
between the mobile
WiMAX network and
the PDN-GW.

nFigure 9. Seamless single-radio handover from mobile WiMax to 3GPP access.
Handover preparation and execution Pre-registration to 3GPP over mobile WiMAX
UE
UTRAN
radio
WiMAX
radio
Target
RNS
User data over mobile WiMAX
Source
mobile WiMAX
ASN
S-GW P-GW ANDSF FAF SGSN HSS
User data over mobile WiMAX
Trigger for ANDSF procedures
Attach request
Attach
request
Location
update
Access
authentication
Attach
accept
Relocation
Ack
Attach
complete
Relocation
required
UE-FAF IP tunnel
Access authentication
Handover required (UTRAN cell list)
Handover request (target UTRAN cell)
Prepare UTRAN resources
UE-FAF IP tunnel
Handover request (target UTRAN cell)
UE-FAF IP tunnel
Handover command (radio info from target UTRAN cell)
UE moves
to the target
UTRAN cell
Handover complete
User data over
UTRAN
User data over
UTRAN
User data over
UTRAN
UE measures the
discovered 3GPP
cells with its
second receiver
At least one
3GPP cell found
Select the target cell
(network-controlled handover)
ANDSF discovery and retrieval of (i) information about neighbor
3GPP cells, (ii) inter-system mobility policies FAF address may be included
as part of the received information (if FAF separate from ANDSF)
Create PDP context
Update mobility binding in P-GW with PMIPv6
Release mobile WiMAX resources
Attach accept
UE-FAF IP tunnel
Attach complete
coordinate in an access-agnostic way greatly simplifies
the mapping functions required for QoS.
In 3GPP EPC it is expected that charging is performed
in the EPC, and only the 3GPP bearer
binding and event reporting function (BBERF)
are required from the ASN-GW (BBERF is a
subset function of WiMAX A-PCEF).

WIMAX-3GPP SEAMLESS MOBILITY

As noted before, in the integrated WiMAX/
3GPP network it is important to provide a seamless
mobility experience to users, that is, enable
mobility across mobile WiMAX radio sites and
other 3GPP radio sites in a transparent fashion.
From the user’s perspective, the seamless experience
conceals the heterogeneity of the system,
and it is conceived as an intelligent system capable
of manipulating its available resources to
provide the best service to the user without any
intervention from the user. This kind of experience
is typically provided, for example, by all
kinds of 2G/3G networks, which facilitate a
user’s mobility across 2G and 3G cells in a fashion
transparent to the user. From the operator’s
perspective, the seamless experience is simply

interpreted as improved key performance metrics
such as availability, drop rates, and throughput.
There are, however, several issues to be
resolved before an integrated mobile WiMAX/
3GPP system can provide a seamless mobility
experience. Some of these issues are further discussed
below.

Handover Decision . Assuming a UE is
using a 3G cell and has discovered (either
autonomously or with assistance from the network)
its neighbor WiMAX cells, the next question
is whether the UE needs to take any
actions (i.e., whether it needs to initiate a handover
to a discovered WiMAX cell). This decision
can be taken by either the UE or the
network. On one hand, it is beneficial when the
handover decision is made by the network
because the network can redirect the UE to
another radio site or frequency that has enough
capacity to handle its ongoing communications.
The network can also coordinate the mobility
of all UEs in a way that overall traffic is evenly
distributed across all radio resources, congestions
are minimized, and total throughput is

IEEE Communications Magazine . October 2008


maximized. On the other hand, the radio network
may lack some parameters that impact the
handover decision, such as user preferences,
the exact type of services active on the UE, and
some operator policies pertaining to mobility
between mobile WiMAX and 3GPP accesses
(e.g., “do not allow handover to 3GPP when a
video streaming service is active”).

The 3GPP Release 8 specifications mandate
that the UE make the decision for handover
between 3GPP and mobile WiMAX, which features
some key advantages. First, the UE can
make a handover decision based on its up-todate
radio measurements, preconfigured user
preferences, and all operator mobility policies
downloaded from ANDSF. Second, the UE does
not need to send any intertechnology radio measurement
to the network. Third, the impact on
the 2G/3G and mobile WiMAX access networks
is minimized because, for example, there is no
need for 3G radio access to receive measurement
reports for WiMAX cells and make decisions
on handover to WiMAX. In addition, there
is no need for 3G radio access to keep track of
the available radio resources on the WiMAX
side and vice versa. Of course, this approach
minimizes the coupling between 3GPP and
mobile WiMAX accesses (and the associated
upgrade cost).

OPTIMIZED HANDOVER

After discussing the above issues pertaining to
seamless mobility across 3GPP and mobile
WiMAX access, we are now ready to present a
specific solution that enables seamless mobility.
This solution is presented and explained though
an example signaling flow illustrating the individual
steps of the handover process from mobile
WiMAX to 3GPP UTRAN access. Due to space
limitations, we consider only one direction of
handover, but the concepts presented can easily
be generalized to the other direction as and can
be easily applied to handover from mobile
WiMAX to 3GPP GERAN access. The careful
reader would be able to identify how this handover
solution addresses the issues discussed
above and how it can achieve seamless mobility
by placing different requirements on the different
network elements. The key aspect of the presented
solution is the capability of the mobile
device to transmit and receive only on one radio
access (either 3GPP or mobile WiMAX) at a
particular time. For obvious reasons, this is
termed a single-radio solution. The advantage of
this solution is that it can eliminate the radio
frequency (RF) coexistence issues faced by a
dual-radio solution and consequently improve
handover performance, but requires more intelligence
in the mobile device and network. A hand-
over solution that requires the UE to
simultaneously transmit and receive on both
mobile WiMAX and 3GPP access during hand-
over (i.e., a dual-radio solution) can be more
simplified than the single-radio solution we consider
here, but it can suffer from performance
issues resulted from RF coexistence, especially
when the WiMAX and 3GPP radio networks are
deployed in neighboring or overlapping frequency
bands.

The single-radio handover solution we present
here is built around a new functional element
in the evolved packet core, called the
forward authentication function (FAF), which is
accessible by the UE over the S14 interface. In
Figs. 6 and 9, the FAF is shown as collocated
with the ANDSF. The need for this new functional
element comes from two restrictions.
First, the UE cannot transmit on the 3GPP side
while operating on the WiMAX side; therefore,
it needs an agent in the network (the FAF) to
authorize its access to 3GPP access and prepare
the appropriate 3GPP resources on its behalf
while the UE is still on the WiMAX side. Second,
we need to minimize the impact on the
3GPP access and mobile WiMAX as much as
possible; thus, a direct link between these two
must be avoided. We also need to avoid the
WiMAX access scheduling measurement opportunities
to the UE in order to measure neighbor
3GPP sites, so we assume that the UE conducts
3GPP radio measurements without any assistance
from the WiMAX network. The UE communicates
with the FAF over a generic IP access network
(e.g., mobile WiMAX access). From the
3GPP access network perspective, the FAF emulates
a simplified radio network controller (RNC)
or base station controller (BSC) for the case of
UTRAN and GERAN access, respectively, while
from the mobile WiMAX access network perspective
the FAF emulates a mobile WiMAX
ASN-GW. The single-radio handover solution is
schematically depicted in Fig. 9 and further
explained next.

The UE uses a source mobile WiMAX access
system and is being served by a P-GW. It is
assumed that the mobile WiMAX network supports
PMIPv6, so a PMIPv6 tunnel has been
established between the mobile WiMAX network
and the P-GW. The UE discovers an
ANDSF in the serving 3GPP EPC, which in this
example is collocated with an FAF. When the
UE successfully discovers an ANDSF/FAF it
establishes a secure connection with it and
receives information (e.g., carrier frequencies)
about neighbor 3GPP access networks as well as
intersystem mobility policies. The UE then measures
the discovered neighbor 3GPP accesses
(including UTRAN cells), and if at least one
provides adequate signal strength, it initiates the
so-called preregistration procedure. As shown in
Fig. 9, preregistration is a typical 3GPP attach
procedure conducted via the secure IP tunnel
between the UE and the FAF while the UE is
still on mobile WiMAX access. It is initiated by
tunneling an Attach Request message (see
Attach procedure in [14]) to the FAF, which
then forwards the Attach Request to the SGSN
over a common Iu-ps interface, as typically done
by a common RNC. This triggers the normal
UMTS authentication procedure, which is conducted
again over the UE-FAF IP tunnel. If the
authentication is successful, the SGSN accepts
the attach request by sending an Attach Accept
message and updates the UE location in the
HSS, according to the normal attach procedure
specified in [14]. Note that neither the SGSN,
nor any other network element in the core 3GPP
network knows that the UE has attached while
still being on WiMAX access.

WiMAX can be

seamlessly integrated
into 3GPP EPC to
enable common
authentication, policy/
charging control,
inter-operator
inter-technology
roaming,
and optimized
WiMAX-3GPP
handover with
single radio.

IEEE Communications Magazine . October 2008


Ongoing activities in
both the 3GPP and
WiMAX forum are
constantly improving
and evolving the
mechanisms for
integration and
interworking of
mobile WiMAX in
3GPP networks.

After preregistration, and when the UE
determines that there is a need to hand over to
UTRAN (e.g., because the WiMAX signal deteriorates
or an operator policy indicates that
UTRAN access is preferable to WiMAX), it
selects a target UTRAN cell either
autonomously or, optionally, with the assistance
of the source mobile WiMAX ASN. The latter
case requires the UE to send a Handover
Required message to the source WiMAX ASN
including a list of candidate UTRAN cells, and
receive a Handover Request response with the
target UTRAN cell selected by the source
WiMAX ASN (e.g., by assessing the resource
availability of all candidate cells). After the target
UTRAN cell has been selected, the UE
transmits a Handover Request message to the
FAF including the target UTRAN cell to which
it wants to hand over. The FAF prepares the
appropriate radio resources on that cell by
using the normal UTRAN relocation procedures
[14] and responds to UE with a Handover
Command message that includes
information about the target UTRAN cell. At
this point, the UE leaves the WiMAX access
and moves to the target UTRAN cell on which
it performs a normal handover execution
according to the UMTS specifications (e.g.,
[14]): a normal Handover Complete message is
sent, and the Relocation procedure is completed.
After that, the UE creates a suitable PDP
context (based on the QoS granted on WiMAX
access) and resumes data communication. Note
that after the creation of the PDP context, the
UE maintains connectivity with the same P-GW
and hence also maintains the same IP address
that was allocated before (i.e., during initial
network entry via WiMAX). This is achieved,
for example, by including special information in
the PDP Context Activation Request message
that helps the S-GW select the same P-GW
already allocated to this UE. Also, during the
PDP Context creation, the PMIPv6 tunnel in PGW
is relocated from the WiMAX ASN-GW to
the S-GW. The S-GW updates this tunnel by
sending a new Proxy MIP Binding Update,
which updates the mobility information in the
P-GW. Finally, note that the UMTS handover
completion and the creation of the PDP context
accounts for a relatively short interruption in
data transmission, which in practice ranges to a
few hundreds of milliseconds. It is important to
note that with single-radio handover the network
(i.e., FAF) controls the resource allocation
in the target system including the data
bearer path. Hence, PMIP is more suitable for
single-radio solutions than are client-based MIP
protocols.

CONCLUSION

In this article we address the integration of
mobile WiMAX with evolved 3GPP networks as
a typical and commercially compelling example
of deploying heterogeneous next-generation
mobile networks. We investigate the architecture
and key procedures that enable WiMAX/3GPP
integration, and introduce a novel handover
mechanism that enables seamless mobility
between mobile access technologies with single-

radio mobile terminals. We conclude that single-
radio handover (i.e., with terminals that do not
need to simultaneously transmit on both access
types) can mitigate the RF coexistence issues
that exist with dual-radio handover mechanisms
at a cost of more intelligence in the network and
terminal.

Ongoing activities in both the 3GPP and
WiMAX forum are constantly improving and
evolving the mechanisms for integration and
interworking of mobile WiMAX in 3GPP networks.
Such integration is becoming a compelling
approach for providing wireless
broadband services and mobility across WiMAX
and 3GPP accesses is becoming seamless and
efficient enough to satisfy the tight mobility
requirement of next-generation mobile networks.

REFERENCES

[1] 3GPP TS 23.401, “General Packet Radio Service (GPRS)
enhancements for Evolved Universal Terrestrial Radio
Access Network (E-UTRAN) Access (Release 8).”
[2] 3GPP TS 23.402, “Architecture Enhancements for Non3GPP
Accesses (Release 8)”.
[3] Y. Bi, M. Song, and J. Song , “Seamless integration
Using Mobile IPv6,” 2nd Int’l. Conf. Tech., Applications
and Systems, 2005, 15.17 Nov. 2005, pp. 1.8.
[4] S. Lee et al., “Inter-RAT Handover Technique from
WCDMA Network to CDMA2000 Network,” 2nd Int’l.
Conf. Tech., Apps. and Sys., 15.17 Nov. 2005, pp. 1.5.
[5] J. Strassner and X. Gu, “Seamless integration and Autonomic
Computing,” Proc. IEEE Consumer Commun. and
Networking Conf, 2007.
[6] A.Dutta et al., “Secured Seamless Convergence across
Heterogeneous Access Networks,” World Telecommun.
Cong. ’06, Budapest, Hungary.
[7] IEEE 802.16e, “Air Interface for Fixed and Mobile
Broadband Wireless Access Systems,” 2005.
[8] WiMAX Forum Network Architecture Stages 2 and 3 .
Release 1, http://www.wimaxforum.org
[9] IETF Internet draft, draft-ietf-netlmm-proxymip6-00.txt,
“Proxy Mobile IPv6.”
[10] C. Perkins, “IP Mobility Support for IPv4,” IETF RFC
3344, Aug. 2002.
[11] 3GPP TS 23.203, “Policy and Charging Control Architecture
(Release 8).”
[12] 3GPP TS 23.402, “3GPP System Architecture Evolution:
Architecture Enhancements for Non-3GPP Accesses
(Release 8).”
[13] 3GPP TS 23.003, “Numbering, Addressing, and Identification
(Release 8).”
[14] 3GPP TS 23.060, “General Packet Radio Service; Service
Description; Stage 2; (Release 8).”
BIOGRAPHIES

POUYA TAAGHOL (pouya@ieee.org) received his Ph.D. from
the Center for Communication System Research (CCSR),
University of Surrey, England, and his B.Sc. from Sharif
University of Technology, Iran. He is currently director of
system architecture at Intel’s Mobility Group, Santa Clara,
California. At Intel he leads the overall system/upperMAC/
services technology development, strategy, and standardization
within IEEE, 3GPP, and WiMAX Forum. Prior to
Intel, he was a founding member of a Silicon Valley startup
(Azaire Networks) and worked as a senior member of
technical staff at Motorola, an NEC affiliation, and as a
research fellow at the University of Surrey. He has been an
active member of 3GPP and the WiMAX Forum, and has
made more than 100 contributions on various topics
(UTRAN, IMS, I-WLAN, and 3GPP-WiMAX interworking).
During his Ph.D., he created and optimized several adaptive
MAC protocols for mixed packet services in wireless
mobile environments. He also created comprehensive
stochastical models for various packet services (VoIP, pure
voice, video streaming, FTP, telnet, HTTP/Web, email). He
has published 15 papers in IEEE, IEE, international satellite
journals, and the American Institute of Aeronautics &
Astronautics (AIAA).

APOSTOLIS K. SALKINTZIS [SM] received his Diploma (honors)
and Ph.D. degree from the Department of Electrical and

IEEE Communications Magazine . October 2008


Computer Engineering, Democritus University of Thrace,
Xanthi, Greece. In 1999 he was a sessional lecturer at the
Department of Electrical and Computer Engineering, University
of British Columbia, Canada, and from October
1998 to December 1999 he was also a post-doctoral fellow
in the same department. During 1999 he was also a visiting
fellow at the Advanced Systems Institute of British
Columbia, Canada; during 2000 he was with the Institute
of Space Applications and Remote Sensing (ISARS) of the
National Observatory of Athens, Greece. Since 1999 he has
been with Motorola Inc. working on the design and standardization
of wireless communication networks, focusing
in particular on UMTS, WLANs LTE, WiMAX, and TETRA. He
has many pending and granted patents, has published
more than 65 papers in referred journals and conferences,
and is a co-author and editor of two books in the areas of
mobile Internet and mobile multimedia technologies. He is
an editor of IEEE Wireless Communications and Journal of
Advances in Multimedia, and has served as lead guest editor
for a number of special issues of IEEE Wireless Commu


nications, IEEE Communications Magazine, and other publications.
His primary research activities lie in the areas of
wireless communications and mobile networking, particularly
on seamless mobility in heterogeneous networks, IP
multimedia over mobile networks, and mobile network
architectures and protocols. He is an active participant and
contributor in 3GPP and vice chair of the Quality of Service
Interest Group of the IEEE Multimedia Communications
Technical Committee. He is also a member of tthe Technical
Chamber of Greece.

JAY IYER is currently a Cisco Distinguished Engineer at
Cisco Systems working on mobile systems. He has over 16
years of experience in architecting, designing and developing
IP networking and mobility systems. He has contributed
towards both WiMAX Forum and 3GPP
standardization activities in the area of QoS, policy, and
mobility. He holds a B.Tech. degree from the Indian Institute
of Technology, Chennai, and an M.S. from Ohio
State University.

IEEE Communications Magazine . October 2008
View All (815)
4G (2) 4G Evolution (1) 5G (35) 5g (1) 802.11 (1) 802.1X (1) ALTO (1) ANDSF (1) AT&T (2) Acceleration (1) Adobe HDS (3) Akamai (6) Amazon (3) Apple HLS (4) Authentication (1) BRAS (2) BT (1) Backbone (4) Backhaul (12) BitTorrent (1) Broadcasting (3) C-RAN (13) C-RAN/Fronthaul (12) CCN (4) CDN (52) CDNi (1) COLT (1) CORD (1) CPRI (2) Cache Control (1) Caching (5) Carrier Cloud (2) Carrier Ethernet (9) Channel Zapping (4) China Mobile (1) China Telecom (1) Cloud (10) Cloudfront (1) DASH (2) DCA (1) DHCP (3) DNS (1) DSA (1) Data Center (7) Dynamic Web Acceleration (1) EPC (5) Energy (1) Ericsson (5) Ethernet (8) FEO (2) Fairness (1) Fronthaul (5) GiGAtopia (1) Gigabit Internet (2) Global CDN (1) Google (5) HLS (1) HTTP (1) HTTP Adaptive Streaming (18) HTTP Progressive Download (3) HTTP Streaming (1) HetNet (1) Hot-Lining (1) Hotspot 2.0 (2) Huawei (3) ICN (4) IP (1) IP Allocation (1) IP Routing (8) IPTV (15) Intel (1) Internet (1) Interoperability (2) IoST (1) IoT (14) KT (22) LG U+ (3) LTE (70) LTE MAC (1) LTE-A (2) Licensed CDN (1) M2M (3) MEC (2) MPLS (25) MVNO (1) Market (4) Metro Ethernet (7) Microsoft (2) Migration (1) Mobile (4) Mobile Backhaul (1) Mobile Broadcasting (1) Mobile CDN (2) Mobile IP (1) Mobile IPTV (3) Mobile Video (1) Mobile Web Perormance (1) Mobility (1) Multi-Screen (7) Multicast (7) NFC (1) NFV (2) NTT Docomo (2) Netflix (6) Network Protocol (31) Network Recovery (3) OAM (6) OTT (31) Ofcom (1) Offloading (2) OpenFlow (1) Operator CDN (14) Orange (1) P2P (4) PCC (1) Page Speed (1) Programmable (1) Protocol (7) Pseudowire (1) QoS (5) Router (1) SCAN (1) SD-WAN (1) SDN (15) SDN/NFV (15) SK Telecom (21) SON (1) SaMOG (1) Samsung (2) Security (6) Service Overlay (1) Silverlight (4) Small Cell (3) Smart Cell (1) Smart Grid (2) Smart Network (2) Supper Cell (1) Telefonica (1) Telstra (1) Terms (1) Traffic (2) Traffic Engineering (1) Transcoding (3) Transparent Cache (2) Transparent Caching (14) VLAN (2) VPLS (2) VPN (9) VRF (2) Vendor Product (2) Verizon (2) Video Optimization (4) Video Pacing (1) Video Streaming (14) Virtual Private Cloud (1) Virtualization (3) White Box (1) Wholesale CDN (4) Wi-Fi (13) WiBro(WiMAX) (4) Wireless Operator (5) YouTube (4) eMBMS (4) eNB (1) 망이용대가 (1) 망중립성 (1) 스마트 노드 (1)

 

 

     
         
     

 

     
     

넷매니아즈 회원 가입 하기

2019년 1월 현재 넷매니아즈 회원은 49,000+분입니다.

 

넷매니아즈 회원 가입을 하시면,

► 넷매니아즈 신규 컨텐츠 발행 소식 등의 정보를

   이메일 뉴스레터로 발송해드립니다.

► 넷매니아즈의 모든 컨텐츠를 pdf 파일로 다운로드

   받으실 수 있습니다. 

     
     

 

     
         
     

 

 

비밀번호 확인
코멘트 작성시 등록하신 비밀번호를 입력하여주세요.
비밀번호