Transforming 3G radio access architecturecongress.fitce.org/2008/paper/64.pdf · Transforming 3G...
Transcript of Transforming 3G radio access architecturecongress.fitce.org/2008/paper/64.pdf · Transforming 3G...
The reason for migration is
higher spectrum effi ci encies
with lower migration cost
(ass um ing 5 MHz spectrum
allocation). New spectrum
allo cations or re-framing may
moti vate mi gration (currently
20 MHz allocations seem very
unlikely but 10 MHz may be
possible).
Introduction
LTE (Long Term Evolution) in anutshell3 GPP LTE (Long Term Evolution) is the
name given to a project within the Third
Gen eration Partnership Project to improve
the UMTS mobile phone standard to cope
with future requirements. Goals include
improving efficiency, lowering costs, improv -
ing services, making use of new spectrum
To continue the evolution of the 3GPP system beyond HSPA and to counter
the emergence of non-3GPP systems, the 3GPP is currently working on Long
Term Evolution (LTE) of the UMTS Radio Access. A main requirement of
UMTS evolution is to reduce the equipment cost by simplifying the number
and the complexity of the nodes and interfaces. This appears to be an entirely
new system, called 3.9G by some, where the functional split between RAN
and CN functions may be reconsidered. This document attempts to identify
the impact of architecture evolution on important functionalities of UMTS
and to compare the performance of different proposals.
opportunities, and better integration with
other open standards. The LTE project is not
a standard, but it will result in the new
evolved release 8 of the UMTS standard,
including mostly or wholly extensions and
modifications of the UMTS system.
The archi tecture that will result from this
work is called EPS (Evolved Packet System)
and com prises E-UTRAN (Evolved UTRAN)
on the access side and EPC (Evolved Packet
Core) on the core side.
The operators benefits of the new air
interface suggested by LTE are the access to a
larger (and variable) spectrum allocations, a
higher spectrum efficiency which implies a
lower cost per bit and the reduced latency
with a better QoS and user experience. The
reason for migration is higher spectrum effi ci -
encies with lower migration cost (ass um ing 5
MHz spectrum allocation). New spectrum
allo cations or re-framing may moti vate mi -
gration (currently 20 MHz allocations seem
very unlikely but 10 MHz may be possible).
LTE has some inherent advantages:
• Optimised for flat architecture (should
lead to lower cost network in the long
term)
• Not burdened by need to support legacy
terminals and protocols leads to
Ayaovi Sossah, Ionut Bibac and Emmanuel Dujardin
Transforming 3G radio access
architecture
Proceedings of FITCE Congress 2008 119
Session 06 : Paper 04
Figure 1. Evolved system architecture
Transforming 3G radio access architecture
optimised spectrum efficiency and
latency performance
• Variable channel BW and harmonised
FDD/TDD enables greater flexibility to
exploit different band allocations.
• Higher capacity per site should lead to
lower cost/bit at high traffic levels (i.e.
at low/medium traffic levels it is prob -
ably cheaper to stick with HSPA+)
The main triggers for deploying LTE will
be:
• High traffic growth rate, where the
(expected) higher initial investment cost
of LTE is quickly recovered by a fast
transition into the lower cost/bit phase.
• When existing sites can no longer serve
the required traffic with available spec -
trum (i.e. additional sites would be
required)
• Spectrum reframing where we can take
advantage of the flexible channel BW and/
or better potential use of TDD spectrum
• New application (e.g. FWA/nomadic) in
new/reframed spectrum
• Capability to support new service and/or
competition with other technologies that
requires the lower latency of LTE to
achieve good/equivalent customer
satisfaction
Figure 1 shows the evolved system
archi tecture, possibly relying on different
access technologies (extract of TR 23.882):
New reference points have been
defined:
S1: It provides access to Evolved RAN radio
resources for the transport of user plane
and control plane traffic. The S1
reference point shall enable MME
(Mobile Management Entity) and UPE
(User plane Entity) separation and also
deployments of a combined MME and
UPE solution.
S2a: It provides the user plane with related
control and mobility support between a
trusted non 3GPP IP access and the SAE
Anchor.
S2b: It provides the user plane with related
control and mobility support between
ePDG (Evolved Packet Data Gateway)
and the SAE Anchor.
S3: It enables user and bearer information
exchange for inter 3GPP access system
mobility in idle and/or active state.
S4: It provides the user plane with related
control and mobility support between
GPRS Core and the 3GPP Anchor and is
based on Gn reference point as defined
between SGSN and GGSN.
S5a: It provides the user plane with related
control and mobility support between
MME/UPE and 3GPP anchor.
S5b: It provides the user plane with related
control and mobility support between
3GPP anchor and SAE anchor.
S6: It enables transfer of subscription and
authentication data for authenti cating/
authorising user access to the evolved
system (AAA interface).
S7: It provides transfer of (QoS) policy and
charging rules from PCRF (Policy
Control and Charging Function) to
Policy and Charging Enforcement Point
SGi: It is the reference point between the
Inter AS Anchor and the packet data
network. Packet data network may be
an operator external public or private
packet data network or an intra
operator packet data network, e.g. for
provision of IMS services. This
reference point corresponds to Gi and
Wi functionalities and supports any
3GPP and non-3GPP access systems.
The interfaces between the SGSN in
2G/3G Core Network and the Evolved
Packet Core (EPC) will be based on the GTP
protocol. The interfaces between the SAE
MME/UPE and the 2G/3G Core Network
will be based on the GTP protocol.
Evolved-UTRAN architecture
options
A. Centralised architectureThe RRC protocol termination is located in
the AGW.
The C-plane RNC functionalities are
split between the AGW and the Node B.
There is no inter-Node B interface in the
C-plane.
B. Conservative architectureThe RRC protocol termination is located in
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Figure 2. The centralised architecture
Figure 3. The conservative architecture
the CPS (Control Plane Server) central
node.
The C-plane RNC functionalities are
split between the CPS and the Node B.
There is an Iu-like interface between the
AGW and the CPS.
There is a simplified Iur-like interface
between CPS, used for example to transfer
the UE context during inter-CPS handover.
It may also be used for neighbour cell
measurement configuration and reporting.
There is an Iub-like interface between
the CPS and the Node B .There is no direct
interface between the AGW and the Node B
in the C-plane. There is no inter-Node B
interface in the C-plane.
C. The flat architecture:Flat architecture allows the Node B to
connect directly the Internet through a Gi
interface. The RRC protocol termination is
located in the Node B. All the C-plane RNC
functionalities are located in the Node B.
The solution has serious issues with
mobility in urban environment, security,
QoS support (e.g. real-time) and admission
control.
Transport network options
The transport network solutions in LTE are:
GTP (GPRS Tunneling Protocol) and MIP
(Mobile IP)-based.
A. GTP GTP is a tunneling protocol that has been
defined by 3GPP. GTP stands for GPRS
Tunnelling Protocol. In GPRS, it is used
between the GGSN and the SGSN (LLC
termination) and in UMTS it has been
extended to the RNC (RLC termination). In
LTE it could be extended to the Node B
(RLC termination).
In LTE, we focus on GTP between EPC
and NodeB. GTP is transported over UDP/IP
and consequently it introduces two IP
levels. The advantage of GTP is that it can
transport transparently any kind of user
data (either IP packets or PPP frames).
GTP is connection oriented; the GTP
tunnel is established once and it has to be
changed only in case of mobility of the UE
between Node Bs.
B. Mobile IP adaptation to LTEtransport network Mobile IP may be chosen by SAE to handle
inter-system mobility, more specifically
between 3GPP and non-3GPP systems. In
this case, Mobile IP is controlled either by
the UE or by a Core Network entity. Mobile
IP-based solutions have been proposed for
the RAN with a will to harmonise RAN and
Core protocols towards an ‘all IP’ system.
That means that all the traffic between
the Node Bs and the ‘operator IP core
Network’ is transported directly over IP
(without any GTP tunnel) with the use of a
Proxy Model Mobile IPv6 Regional
Registration/Forwarding. The key elements
of the solution are:
• Based on Proxy Mobile IP, but
• Only between Node B and AGW
• IP address of the UE is not changed
in case of intra-system mobility
• Proxy-Mobile IP protocol is used to
update the path during handover
• Additional signalling needed for
e.g. UE context transfer
• IP address swapping in the AGW and in
the Node B for each downlink IP packet
• IP header insertion for each uplink IP
packet
C. Comparison and conclusion:It should be stressed that both options are
only applicable if RLC is terminated in
Node B. Currently we have not put in
evidence any significant difference in the
efficiency of the two options. MIP-based
option permits to offer homogeneous
solution for intra and inter-system mobility.
The protocol stack is also simpler and this
solution is particularly efficient for IPv6 UE.
Radio resource management
Radio Resource Management (RRM)
algorithms are responsible for the efficient
utilisation of the air interface resources. The
RRC layer contains RRM functions: Radio
Bearer Control, Radio Admission Control,
Connection Mobility Control, Dynamic
Resource Allocation, and Inter-cell RRM.
We can distinguish two main types of
architecture proposals:
• Distributed architecture: the RRC is
located in the Node B. Several levels
can be distinguished.
• Centralised architecture: the RRC is
located in a Central Node. Some
vendors propose to terminate RRC in
the Access Gateway. Other vendors
propose a central node called Control
Plane Server (CPS).
In the following section, we study very
briefly the impact of the architecture pro -
posals, and especially of the location of
RRC, on each RRM function.
A. Radio Bearer Control Radio Bearer Control (RBC) concerns the
configuration of control channels used to
control the different bearers, and the con -
figuration of the protocol entities in the UE
and the RAN.
If Radio Bearer Control is restricted to
Dynamic Resource Adaptation (which may
be the case if shared radio channels are
used, and if there is no macro-diversity),
and if inter-cell interference is not a prob -
lematic issue, then it could be distributed in
the Node B. On the contrary, if macro-
diversity is used, Radio Bearer Control
should be located in a central node con tain -
ing all involved Node Bs. In any case, infor -
mation on neighbouring cells could be
useful for Radio Bearer Control, in order to
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Figure 4. The flat architecture.
Transforming 3G radio access architecture
have a global view on the influence of intra-
cell management on the neighbouring cells.
This does not necessarily require a
Central Node, and could be achieved with
the Common RRM database proposed by
Nortel, or via Inter-Node B load infor mation
exchange. Such schemes can be seen as
optimisation schemes; however they may
prove very useful or even man datory in
high capacity systems, depending on the
influence of inter-cell interference on the
network’s performance.
B. Radio Admission ControlRadio Admission Control (RAC) is the
decision to accept or reject a requested
radio service. This decision is based on the
availability of the needed resources, and on
whether the admission would not endanger
the availability of resources for the already
admitted services.
If load information is requested, and if
periodical/event-triggered load update is
not too costly compared with event-based
load information request, centralised
architecture is more efficient in terms of
signaling.
However, if load information is not
requested, distributed architecture is clearly
more efficient. An interesting trade-off
could be to use distributed architecture with
central database, provided that periodical
load update of the database is not too costly
(which will depend on the period and on
the interface between Node B and central
database).
C. Connection Mobility ControlCell reselection is controlled by the UE in
idle mode. But it is possible to restrict the
access to a cell for load reasons. In Active
mode, the decision to move a connection
from one cell to another is based on the
radio conditions obtained by UE radio
measurements, and also possibly on other
conditions (load, traffic distribution), and
on strategies defined by the operator.
We can point out that in the distributed
architectures, handover algorithms are dup -
licated in each Node B, whereas in the cen -
tralised architecture, the central node only
contains the handover algorithm. Contrary
to Radio Admission Control, load infor ma -
tion on neighbouring cells is almost man da -
tory to achieve efficient handovers in terms
of user's QoS and global traffic repartition
on the network. Besides, context transfer is
an important issue that may be limiting for
distributed architectures. As a consequence,
we recommend using centralised archi -
tecture for connection mobility control.
D. Dynamic resource allocation(scheduling)
Dynamic Resource Allocation (DRA) con -
cerns the transmission of physical resources
(transmit power, frequency, time, space). For
packet-switched services, resources must be
allocated and de-allocated in real time, in
accordance to the availability of data for the
individual connections, the quality of radio
channel and the decision of a scheduler to
transmit the data of selected connections.
There is a common agreement that Dynamic
Resource Allocation will be located at the
Node B. This is in line with the work per -
formed in UMTS Rel-6- HSDPA, where DRA
is already in the Node B. Indeed, DRA only
concerns intra-cell resources and users that
have already been admitted. If we assume
that a pool of radio resources is allocated to
each cell, then each Node B can indepen -
dently manage these resources under certain
conditions (on interference and load). DRA
is based on user terminal's measurements.
Conse quently, DRA will be faster if it is
located near to the radio, e.g. in the Node B.
E. Inter-cell RRM (interference andload management)Inter-cell RRM is used to mitigate inter-cell
interference and support unequal loading of
cells. Depending on the mobility of users
and the dynamic of data-rates changes, even
Dynamic Inter-cell RRM may be required.
Several RRM algorithms can enable to
achieve load sharing between cells:
• Radio admission control ensures that
newly admitted calls would not deterior -
ate already-admitted call, on the studied
cell and on its neighbouring cells (via
admission control algorithms that take
into account the load of several cells)
and redirects calls at admission to less
loaded cells (via Directed setup).
• Handover
F. ConclusionWe propose a synthesis of the relevance of
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RRM Distributed Distributed Centralised
function architecture architecture architecture
with central
database
Radio
Bearer
Control – † –
Radio
Admission
Control – † –
Connection
Mobility
Control – - ‡
Dynamic
Resource
Allocation ‡ ‡ –
Inter-cell
RRM – – ‡
Figure 5. Synthesis on the adaptation of
each architecture type to RRM functions
– very bad, - bad, † good, ‡ very good
Main advantages Main drawbacks
Flat architecture Great reactivity of handover because Handover decision in each Node B
the decision is taken as close as (Difficulty to have a coherent policy
possible to the UE with different manufacturers).
Signaling in RAN optimised Need of UE context transfer
(UE measurements sent to and between Node Bs for each handover
used in the Node B). The Node B is complex (Handover
Few interfaces to be defined preparation, pre-decision and execution
+ IP address swapping (also in AGW))
Complex Inter-system handover
Conservative High handover success rate because Handover reactivity sub-optimal
architecture the decision is taken where all the (Measurements have to reach the CPS)
measurements are reported Very complex signaling in the RAN
No need for direct signaling interface (Several different entities and
between Node Bs protocols involved).
Only one handover algorithm
(Easy to configure by the operator
(coherent policy)
Node B is simple
Centralised No need for direct signaling interface Handover reactivity sub-optimal
between Node Bs (Measurements have to reach the AGW)
Only one handover algorithm Scalability (AGW needs to handle all the
(Easy to configure by the operator all the UE in its area).
(coherent policy)
Node B is simple
Figure 6. Hand Over procedure comparison.
the three architectures regarding each RRM
scheme:
We have favored distributed architecture
with central database for Radio Bearer
Control and Radio Admission Control,
because this architecture enables to obtain
load information without losing the benefit
of having a low latency between user
terminal's measurements and the decision
(by putting this decision in the Node B).
Besides, we assume that for these functions,
averaged load information on quite large
time-scale is sufficient for taking an
accurate decision, as these functions may
only influence inter-cell interference.
Inter-system hand over
procedure
We highlight some points that seem to be
important for the choice of LTE architecture.
First, the interruption time during the
handover is independent of the architecture
option; this is only true for a predictive
handover.
Regarding handover reactivity, it is clear
that the handover can be triggered faster if
flat architecture is chosen. But if load infor -
mation on target cell is unavailable or not
up to date there is a risk of handover failure
and consequently a try on another cell is
needed. If the UE is moving fast, the call
could also be dropped. If up-to-date load
information on neighbour cells needs to be
taken into account to minimise the failure
probability, the handover reactivity will be
worse.
The addition of an RRM server should
reduce the signaling and the delay in this
case.
Regarding inter-system handover, the
complexity is higher if flat architecture.
The handover procedure itself is very
simple for centralised architecture because
there is no packet forwarding and no
context transfer but only retransmission.
To conclude, the table hereunder
summarises the main advantages and
drawbacks of the different architectures
from the handover procedure point of view.
Security aspects
A. Traffic types identificationSeveral types of traffic flows can be
identified in LTE:
• Traffic terminating in the UE: RRC
signaling flow + NAS signaling flow
+ User data
• Traffic not terminating in the UE:
Signaling on the ‘vertical’ interfaces (i.e.
between AGW or CPS and Node B, as
well as between AGW and CPS, for
RANAP-like signalling) and Signalling
on the ‘vertical’ interfaces. (i.e. between
AGW or CPS and Node B, as well as
between AGW and CPS, for RANAP-like
signalling).
B. LTE security options:The LTE option depends on the LTE archi -
tecture summarised in Figure 7:
Centralised and Conservative architectures
In some vendor’s proposals, none of the
RRC, NAS and user data flows are known in
the Node B.
▪ In one case, different security
algorithms may be supported by the
CPS and by the AGW (MME/UPE).
Negotiation between the MME, CPS and
UE would be needed to select the RRC
flow integrity protection algorithm.
Negotiation between the MME and UE
would be needed to select the NAS flow
integrity and ciphering algorithms. If
the MME and UPE were located in two
different nodes, negotiation between the
MME, UPE and UE would be needed to
select the user data flow-ciphering
algorithm. A Set of keys will be
available in the MME, transmitted in a
secured way from the MME to the CPS
and UPE.
▪ In the case, the same security
algorithms could be used in the AGW
(combining RRC/MME/UPE),
negotiated between the MME and the
UE. If the RRC/MME and the UPE are
located in two different nodes, another
negotiation between the MME, UPE and
UE would be needed to select the user
data flow ciphering algorithm and the
ciphering key should be transmitted in a
secured way to the UPE.
Flat and optimised flat architecture
▪ Option A
Only RRC signaling is known in the
Node B. Different integrity protection
algorithms may be supported by the
Node B and AGW (MME): Negotiation
between the MME, Node B and UE
would be needed to select the RRC flow
integrity protection algorithm and
negotiation between the MME and UE
would be needed to select the NAS
integrity protection algorithm. Different
ciphering algorithms may also be
supported by the MME (for NAS) and
UPE (for user data) if these entities are
located in different nodes (the
negotiation of these algorithms should
be E-UTRAN transparent). The set of
keys available at the MME should be
transmitted in a secured way from the
MME to the UPE and Node B. RLC is
not located with NAS and user data
security functions. If the security
algorithms need input to modify the key
stream to be added to each plain text
block, the RLC sequence number
cannot be used.
▪ Option B
All types of UE terminating traffic (RRC,
NAS, user date) are known in the Node B.
All the security functions being
implemented in the Node B, only one
set of security algorithms needs to be
negotiated between the MME, Node B
and UE. It should be checked if a single
set of keys available at the MME could
be used in the Nodes B, and transmitted
in a secured way from the MME to the
Nodes B (one set per Node B is
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Proceedings of FITCE Congress 2008 123
Session 06 : Paper 04
Figure 7. LTE Architectures
proposed by Nokia).
The RLC is collocated with RRC, NAS
and user data security functions in the
Node B. If the security algorithms need
input to modify the key stream to be added
to each plain text block, the RLC sequence
number (or radio frame number for RLC
TM) can be used.
Additionally, IPSec mechanisms need to
be implemented in the transport network
for NAS and user data flows, adding some
overhead and significant processing time for
real time traffic.
▪ Option C
RRC signaling and user data are known
in the Node B.
Different integrity protection algo rithms
may be supported by the Node B and
AGW (MME): Negotiations between the
MME, Node B and UE would be needed
to select the RRC flow integrity pro tection
algorithm and negotiations between the
MME and UE would be needed to select
the NAS integrity pro tection algorithm.
Note that if RRC ciph er ing is required,
different ciphering algorithms may be
sup ported by the Node B (for RRC) and
UPE (for user data). Negotiations be tween
the MME, Node B and UE would be
needed to select the RRC flow-cipher ing
algorithm and negotiations between the
MME, UPE and UE would be needed to
select the user data-ciphering algo rithm.
The set of keys available at the MME
should be transmitted in a secured way
from the MME to the UPE and Node B.
The RLC is collocated with RRC and
user data security functions, but not
with NAS security functions. As for
option A, there is an open issue for NAS
sequence numbering.
C. Synthesis and conclusion:In any option, the radio interface is equally
protected (if no physical access to the Node
B).
In case of physical access to the Node
B, protection against the following attacks
is not supported:
▪ Option A: Denial of service (e.g. false
HO messages).
▪ Option B: Denial of service,
Eavesdropping, Theft of service, User
identity and location exposure.
▪ Option C: Denial of service,
Eavesdropping, Theft of service.
Within the different options proposed
for the Flat and Optimised flat architectures,
option A, presenting UE context transfer
through vertical interface (Nortel's solution)
offers the best level of security. The level of
security is slightly better with the
Centralised architecture.
With regard to the complexity of the
specification and implementation, option A
is more complicated than the Centralised
architecture and similar technical issues
must be solved in both cases.
Conclusions
The E-UTRAN architectures described in the
previous sections are compared and marks
are given to each of them for a number of
criteria gathered in several sets.
• With regard to latency:
• There is not much difference between
the proposals in the U-plane.
• The C-plane latency is slightly worse
with the centralised architecture, and
significantly worse with the
conservative architecture.
• With regard to RRM and handover:
• The centralised and conservative archi -
tectures reach a good efficiency with a
limited complexity (no need for inter-
Node B interface, but flex mechanisms
to be defined at the interface between
AGW and Node B), even if the hand -
over decision may be far from the radio
node with the centralised architecture.
• Protocols are executed quickly with the
flat architectures (because made near
the radio interface), but the decision
algorithms may not be optimal because
distributed. This could give high rate of
handover failures in loaded conditions.
The optimised flat architecture is an
accept able improvement because it
brings a better view of the neighbou r -
hood in every Node B, but it adds com -
plexity of nodes and interfaces, and
may impact the latency.
• With regard to the complexity:
• The complexity is distributed in the
Nodes B with flat and optimised flat
architectures whereas it is mainly
located in the AGW with the centralised
and conservative architectures. Cen tral -
ised AGW may then cover smaller geo -
graphical areas than AGW controlling
flat architectures.
• The complexity of the horizontal inter-
Node B interface in flat and optimised
flat architectures may be compared to
the complexity of the vertical interface
between AGW and Node B in the cen -
tral ised architecture. However, for a
given Node B, the number of vertical
interfaces towards the AGW (within a
pool area) in the centralised is less than
the number of horizontal interfaces
towards its neighbour Nodes B in the
flat architectures.
• With regard to security, MBMS, mi gra -
tion and inter-system mobility, are
much easier to achieve with a central -
Transforming 3G radio access architecture
Proceedings of FITCE Congress 2008124
Session 06 : Paper 04
ised architecture. Similar level of effici -
ency is however reachable with flat
archi tectures, but by adding further
com plexity. Flat architectures are also
less future-proof and the introduction of
new features may be very difficult.
It is proposed to support the definition
of a central node in the E-UTRAN, support -
ing RRM features for inter-Node B cell load
and interference measurement handling. It
is also proposed to terminate the RRC above
the Node B.
References
1 3GPP TR 25.913, Requirements for
Evolved UTRA (E-UTRA) and Evolved
UTRAN (E-UTRAN), (Release 7), V7.1.0
(2005-09)
2 3GPP TR 25.814, Physical Layer Aspects
for Evolved UTRA, (Release 7), V1.0.1
(2005-11)
3 3GPP TR R3.018, Evolved UTRA and
UTRAN, Radio Access Architecture and
Interfaces, (Release 7), V0.0.2 (2005-10)
4 3GPP TR 23.882, 3GPP SAE: Report on
Technical Options and Conclusions,
(Release 7), V0.9.0 (2005-12)
5 3GPP TR 23.933, IP transport in
UTRAN, (Release 5), V5.4.0 (2003-12)
6 3GPP TS 33.210, 3G Security, Network
Domain Security, IP network layer
security, (Release 6), V6.5.0 (2004-06)
7 3GPP TR 25.881, Improvement of RRM
across RNS and RNS/BSS, (Release 5),
V5.0.0 (2001-12)
Acronyms
2G Second Generation
3G Third Generation
3GPP Third Generation Partnership
Project
AAA Authentication, Authorisation,
Accounting
AAL2 Asynchronous Transfer Mode
Adaptation Layer 2
BSC Base Station Controller
BTS Base Transceiver Station
C-plane Control plane
CK Cipher Key
CMC Connection Mobility Control
CN Core Network
CS Circuit Switched
E-UTRAN Evolved UTRAN
E2E End-to-End
EDGE Enhanced Data rates for GSM
Evolution
FACH Forward Access Channel
FDD Frequency Division Duplex
Gb Interface between an SGSN and a
BSS
GERAN GSM EDGE Radio Access Network
GGSN Gateway GPRS Support Node
GMM GPRS Mobility Management
GPRS General Packet Radio Service
GSM Global System for Mobile
communications
GSN GPRS Support Node
GTP GPRS Tunnelling Protocol
HO Hand Over
HSDPA High Speed Downlink Packet
Access
HSS Home Subscriber Server
IETF Internet Engineering Task Force
IMSI International Mobile Subscriber
Identity
IP Internet Protocol
Iu Interface (reference point)
between RNC / BSC (RAN /
GERAN) and CN
Iub Interface between RNC and Node B
Iur Interface between RNC
LAN Local Area Network
LTE Long Term Evolution
MAC Medium Access Control
MIP Mobile IP
MBMS Multimedia Broadcast Multicast
Service
MN Mobile Node
MS Mobile Station
OAM Operation, Administration,
Maintenance
OFDMA Orthogonal Frequency Division
Multiple Access
OMC Operation and Maintenance Centre
PS Packet Switched
QoS Quality of Service
RA Routing Area
RAB Radio Access Bearer
RAC Radio Admission Control
RACH Random Access Channel
RAN Radio Access Network
RRM Radio Resource Management
RTP Real-time Transport Protocol
SAE System Architecture Evolution
SC-FDMA Single Carrier – Frequency
Division Multiple Access
SGSN Serving GPRS Support Node
SIM Subscriber Identity Module
SRNC Serving RNC
TCP Transmission Control Protocol
U-plane User plane
UMTS Universal Mobile Telecommu nica -
tion System
USIM Universal SIM
UTRA Universal Terrestrial Radio Access
UTRAN Universal Terrestrial Radio Access
Network
VoIP Voice over IP
WCDMA Wide-band Code-Division Multiple
Access
Transforming 3G radio access architecture
Proceedings of FITCE Congress 2008 125
Session 06 : Paper 04
Ayaovi Sossah
gradu ated from MP-telecom - ENIC LilleFrance in telecom mu -ni cations, electronicsand electrotechnics.Since graduation, he isin charge of radioaccess part for 3G,
HSxPA for different contractors such asAlcatel, Siemens and currently for Nokia(NSN). He is currently following IMStraining with the goal of being able totroubleshoot the network end to end. Hehas 5 years telecommunicationexperience.
Ionut Bibac, PhD,has 15 years tele com -munication experi -ence. He graduatedfrom the UniversityPolitehnica of Buch a -rest, Faculty of Elec -tronics and Telecom -munication, in 1993,
with specialisation in optoelectronics. In2002, he obtained his PhD with the thesisentitled ‘Optimization problems of opticalTransmission of Information’ at the aboveuniversity, ‘Cum Laude’. At present he isworking for SNCD as GSM-R teamleader.
Emmanuel Du jar -
din received a degreein tele com mu nicationsengineering from theENST Bretagne(France) and a masterof science in opticaltechnologies from theUniversite de Bret -
agne Occidentale in 2001. In October2001, He started working in FranceTelecom as an R&D engineer. During fiveyears, He has been involved in testingUMTS equipment in OAM (OperationAdministration and Maintenance) andtelecom domain (protocol, performance,endurance, load and stress). He partici -pated at the same time in several stand -ardisation fora related to OSS manage -ment (3GPP SA5 and TISPAN WG8). Hejoined Orange Corporate towards theend of 2006 and leads the process testingand experimenting the UMA VendorsProduct enabling the subsidiaries tolaunch their market trials.
The authors