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

Proceedings of FITCE Congress 2008120

Session 06 : Paper 04

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

Transforming 3G radio access architecture

Proceedings of FITCE Congress 2008 121

Session 06 : Paper 04

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

Proceedings of FITCE Congress 2008122

Session 06 : Paper 04

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

Transforming 3G radio access architecture

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