1- RAN Enhancements for Advanced MBMS

7/30/2019 1- RAN Enhancements for Advanced MBMS

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Contribution to the WWRF17 Meeting

1 WG or SIG to which this Contribution is submitted:

WG4

2 State which of the categories a) f) on the front page of the CfC thisContribution is addressing:

Identifying new research areas

3 Title of research item

RAN Enhancements for Advanced Multimedia Broadcasting and Multicasting Services

4 Contact details of author/submitter

Rainer Hoeckmann

University of Applied Sciences Osnabrueck

Postfach 1940

49009 Osnabrueck

[email protected]

Phone: +49 541 969 3800

5 Subject area (WG/SIG and subtopic (as of CfC) where appropriate)

WG4 New Air Interfaces, Relay based Systems and Smart Antennas

Several subtopics will be covered

6 Relevance of the topic to the above subject area

The IST project C-MOBILE (Advanced MBMS for the Future Mobile World) intends to present itsidentified research directions for RAN.

7 Preferred presentation form:

speech

8 Abstract

see below


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AbstractMobile multimedia services like goal notification

for football fans by Multimedia Messaging Service (one club =

one channel) and mobile television require efficient technologies

in order to distribute multimedia contents simultaneously to

large mobile user groups. UMTS (Universal Mobile

Telecommunications System) Release 6 has standardised

MBMS (Multimedia Broadcast and Multicast Services) for the

first time. This paper discusses issues for evolving mobile

broadcast services with higher bandwidth and more flexibility.

The document discusses the future research directions

concerning RAN enhancements for the provision of advanced

Multimedia Broadcast Multicast Services. A particular focus is

given on the RAN enhancements addressed in the European

project C-MOBILE.1

Index TermsImproved MBMS Support, Research

Directions, RAN Evolution

I. INTRODUCTION

Mobile multimedia services like goal notification for

football fans by Multimedia Messaging Service (one club =

one channel) and mobile television require efficient

technologies in order to distribute multimedia contents

simultaneously to large mobile user groups [1][2]. UMTS

(Universal Mobile Telecommunications System) Release 6

has standardised MBMS (Multimedia Broadcast and

Multicast Services) for the first time [3][4]. The C-MOBILE

project deals with enhancements to MBMS radio and core

network capabilities in future wireless cellular networks,

mobile broadcast service infrastructure capabilities andconvergent architecture. This paper is based on the first

deliverable [5] by the Work Package 3 RAN

Enhancements of C-MOBILE [6].

In section II, the status in standardization is reviewed and

specific RAN enhancements are classified.

Section III summarizes concepts and technologies

currently under discussion in standardization and section IV

concludes the discussion.

II. TECHNOLOGIES AND CONCEPTS FOR 3GPPEVOLUTION

A. WCDMA based MBMS Evolution in 3GPPWith the 3GPP Release 99 and Release 5 standards being

This contribution is the result of work done as part of the IST C-

MOBILE project (IST-2005-27423) [6].

frozen, enhancements can be applied on the receiver side or

on certain non-standardized algorithms. Relevant techniques

are:

Interference cancellation (IC) in order to mitigate inter-

cell and/or intra-cell interference, as it is interesting for

HSDPA Release 5. Adaptive IC scheme that allow foran intelligent trading of receiver complexity vs.

performance are worth to be studied.

Receive diversity for an improved coverage and/or in

order to reduce the transmit power at the base station.

Receive diversity schemes designed for interference

nulling. This advanced technique does not optimize for

SNR (signal-to-noise ratio) via maximum-ratio

combining, but for the SINR (signal-to-interference

and noise ratio).

Improved HSDPA scheduling, traffic-channel

switching, RRM. Since the standard does not specify

these algorithms, more sophisticated proprietarysolutions can be applied

C-MOBILE will consider various possibilities to enhance

the MBMS Release 6 performance, and consider concepts

and technologies already listed in the Release 7 Study Item

MBMS Release 6 Evolution, comprising techniques such

as:

Selection and Soft Combining.

Advanced counting procedures for a more efficient

utilisation of system resources, in order to avoid

congestion resulting from uncontrolled terminal

feedback. Better MBMS mobility support and optimizations for

MBMS reception during cell change.

Improved ptp-ptm (point-to-point vs. point-to-

multipoint) switching, for optimized overall cell

throughput as well as to guarantee a certain QoS at the

UE.

Optimizations for scenarios where the RNC does not

know whether the UE supports the MBMS ptm

reception in the CELL_DCH state.

Provision of an MBMS dual receiver to permit joint

ptp and ptm reception, or the handling of MBMS

services on different frequencies. The study of MBMS on the HSDPA transport channel.

Finally, broadband MBMS support based on MC-

WCDMA will be considered.

RAN Enhancements for Advanced Multimedia

Broadcasting and Multicasting Services

E. Alexandri

1

, J. Antoniou

2

, T. Clessienne

1

, A. Correia

3

, R. Dinis

3

, E. Hepsaydir

5

,R. Hckmann4, H. Schotten

6, C. Sgraja

6, R. Tnjes

4, N. Souto

3, S. Wendt

1

1France Telecom,

2Univ. of Cyprus,

3ADETTI,

4Univ. Appl. Sci. Osnabrck,

5Hutchison 3G,

6Qualcomm


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There are various scenarios where MBMS services might

be delivered on unicast bearers. It is expected that there will

be an HSPA evolution, and that HSDPA+ bearers might

be used for MBMS service support.

B. LTE based MBMS evolution in 3GPPThe overall target of the 3GPP long-term evolution (LTE)

of 3G is to arrive at an evolved radio access technology that

can provide service performance on a par with current fixed

line access. As it is generally assumed that there will be a

convergence towards the use of Internet Protocol (IP)-based

protocols (i.e. all services in the future will be a carried on

top of IP), the focus of this evolution should be on

enhancements for packet-based services.

An OFDMA air interface has been selected for LTE. One

of the LTE requirements is to deliver enhanced MBMS,

where C-MOBILE will study and make necessary proposals

to 3GPP for LTE.

In the LTE architecture as it was proposed, the network

nodes GGSN, SGSN, and RNC will be merged into a single

central node, the Access Core Gateway (ACGW). The

ACGW terminates the control and user planes for the user

equipment (UE) and handles the core network functions as

they are provided by GGSN and SGSN in Release 6.

Link LayerLTE suggests a new link layer concept:

packet-centric link layer. The concept foresees two Layer-2

ARQ protocols, the RLC protocol which contains ARQ

functionality, and the hybrid ARQ (HARQ) protocol

embedded in the medium access control (MAC) layer and

operating between the base station and the UE. This is

expected to allow for more efficient scheduling decisions.

DownlinkOFDM. In OFDM-SFNs (single frequency

networks), the signal from all base stations will appear as

multi-path propagation and thus implicitly be exploited by

the OFDM receiver. In addition, frequency domain

adaptation is made possible through the use of OFDM and

can achieve large performance gains in cases where the

channel varies significantly over the system bandwidth.

Information about the downlink channel quality obtained

through feedback from the terminals, in order to

appropriately select the output power level, channel coding

rate, and modulation scheme by the scheduler.

UplinkSingle-Carrier FDMA. For uplink transmissions,

an important requirement is to allow for power-efficient

user-terminal transmissions by lowering the PAPR (peak-to-

average power ratio) in order to maximize coverage. Single-

carrier FDMA with dynamic bandwidth is therefore

preferred. Slow power control, compensating for path loss

and shadow fading is sufficient as no near-far problem is

present due to the orthogonal uplink transmissions.

MIMO SolutionsTo fulfil the requirements on coverage,

capacity, and high data rates, various multi-antenna schemes

need to be supported as part of LTE. In addition, it is

necessary to consider multi-antenna technologies as a well-

integrated part of an evolved radio access rather than an

extension to the specification.

Since the deployment of LTE requires new spectrum,

some operators might not be in the position to migrate LTE

from the very beginning. Other operators already indicate

that they will deploy LTE in hotspots first and handover the

users to WCDMA in other areas. A third group plans to

deploy LTE from the very beginning with full coverage.

In addition, there are options to use currently unused

spectrum for stand-alone MBMS support that shall however

be closely tied to a 3G system. These MBMS solutions

could be deployed in parallel to any other deployment

strategy providing full or restricted coverage.

III. RANENHANCEMENT TECHNIQUES

A. Improved RRM1) Dynamic Service Area Definition & Resource

Allocation

The MBMS Service Area is defined as the area where

MBMS data of a specific MBMS session are transmitted.

The MBMS Service Area is statically configured in the RNC

in Release 6, and research is needed to investigate theadvantages of using dynamic MBMS Service Area definition

together with mechanisms to achieve this goal.

In addition, to improve the overall system capacity, an

MBMS service delivery into a handset can be scheduled

when the network is less loaded.

2) Improved Packet SchedulingHS-DSCH is currently used for unicast services due to its

point-to-point nature, but the rich features such as adaptive

coding and modulation (ACM), fast scheduling, hybrid ARQ

and short TTI, make the HS-DSCH a good candidate for

multicast services. Users belonging to the same MBMS

group will have the same H-RNTI (HS-DSCH Radio

Network Temporary Identifier). Further research has to

study and propose algorithms for the packet scheduler in the

base station defining how to use the CQI reported by the

MBMS UEs. The study should also quantify the benefit of

using MBMS on HS-DSCH.

Streaming is one of the most expected MBMS services. A

typical feature of streaming applications is that they do not

require as strict and small delay bounds as conversational

applications do. The use of a receiver buffer makes a

streaming application resistant against latencies. In order to

avoid under- and overflows and therewith packet loss, the

scheduler must have the information of the state of the

receivers buffers.

As the HSDPA-related MAC functionality resides in the

base station, fast per-TTI packet scheduling (PS) in

coherence with the instantaneous radio link quality is

possible.

Two types of fairness of the scheduler can be considered:

Fair Scheduling and Unfair Scheduling. A simple type of

channel non-adaptive scheduling, known to allocate the

access times fairly, is the Round Robin (RR) scheduler.

However, although the time allocation of RR is fair, the

performance is mostly not very encouraging in fading

environments. Improved schemes for efficient packet

scheduling are therefore of relevance.


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3) New Retransmission SchemesHybrid ARQ is well defined for unicast services. In the

case of multicasting, there could be many variants. Suppose

a frame is to be delivered to a number of users in a multicast

group. After the initial transmission, some users may have

successfully decoded the message, while the other users still

require retransmissions. Upon the reception of ACK/NACK

feedbacks, the base station will either schedule

retransmission for the NACK users or decide to stop the

transmission, since a majority of users have already got the

frame.

The first approach, i.e., the error free data delivery

required by the file download service, can be guaranteed by

unicast sessions to be set up at the end of the multicast

session for file repair.

4) Enhanced ptp-ptm SwitchingMBMS channel type switching is also possible as per

3GPP Release 6 of the standard. During an ongoing session,

the RNC can decide to switch from ptm to ptp per cell. As

usual the standard does not specify the parameters to be usedby the RNC to make this decision (it is worth highlighting

there may be ptm data delivery between BM-SC, SGSN,

GGSN and RNC, while ptp at the radio level).

Further investigations are needed for efficient mechanisms

to switch from ptp to ptm and vice-versa:

The RNC can set up a ptp (unicast) or ptm (multicast)

radio bearer depending on several parameters, such as

the number of the MBMS users in a cell. The number

of MBMS users per service and per cell can be worked

out through the MBMS Counting mechanism.

MBMS Counting relies on the MBMS Counting

Response message sent by the UEs, when they receivea request for counting.

If the UE is in idle mode, the RRC connection

establishment procedure will be used for counting

purposes, while if the UE is in connected mode the

Cell Update procedure will be used. Counting can be

even activated during an ongoing MBMS session. In

that case the procedure is called re-counting.

In order to avoid that a large number of UEs set up a

RRC connection or send Cell Up-date as a response

from the counting request, the UE is requested to

access the net-work randomly.

Further investigations concern the impact of different

channels for ptp and ptm modes such as HS-DSCH

(ptp) and DSCH (ptm). If a ptm bearer is chosen, then

the transport channel to be used will be FACH. If a ptp

bearer is selected, then the transport channel which can

be used is either DCH or HS-DSCH.

Also, the role of power in the switching decision

between ptp and ptm cell modes will be studied, in the

case that power is an efficient metric such as, for

example, when switching between DCH and FACH.

5) Improved MBMS Counting3GPP specifications address the issue of ptp-ptm

switching by means of the MBMS counting mechanism.

However, the counting process was initially developed

without considering the possibility of using macro-diversity

techniques in ptm common channels, and MBMS users are

counted independently in each cell. Some extensions to this

counting process are proposed in this document as well as a

discussion about the criteria method used by this

mechanism.

We propose to analyze radio resource management

methods concerning the efficient usage of the current

UMTS radio resources for broadcast/multicast kind of

services.

MBMS counting should be used to decide whether the

identical MBMS service should be transmitted in a ptp

or ptm mode to a group of users. The proposed strategy

is based on the total transmit power in a cell.

Macro-diversity combining for ptm connections is

crucial for MBMS, as improving significantly the

received signal quality at the receiver and therefore

offering a substantial de-crease in transmit power. In a

multi-cell transmission, instead of avoiding

interference at the cell border, all the neighbouring

cells are used to transmit the same information

synchronously to the UE, which requires an extended

counting scheme.

As a final remark, a hybrid MBMS counting mechanism

based first on the number of UEs and then, if applicable, on

the instantaneous transmit power of both ptp and ptm

transmission modes should be considered for study. While

maintaining the same MBMS counting mechanism mode for

a large group of users, this may provide a more accurate

decision method being worthwhile in terms of radio resource

availability.

6) MBMS Cell Throughput EnhancementsResearch projects, such as C-MOBILE, have to

investigate how to increase the MBMS throughput. Forexample, it is proposed to specify the behaviour of UEs with

a dual receiver. These UEs will be able to receive

simultaneously dedicated services on one frequency and

MBMS services on the other frequency.

Cell throughput could also be investigated in terms of

efficient admission control mechanisms that would consider

QoS considerations including both service differentiation

and the bimodal nature of the cells (i.e., ptp or ptm).

Efficient Admission Control schemes will consider the se-

lected channels used and the handover specific requirements,

and can also be hybrid in nature to handle the change of cell

mode from ptp to ptm and vice versa, to achieve the bestpossible cell throughput.

7) Multicast Mobility SupportThe user shall be able to continue receiving MBMS

services throughout the MBMS service area in which the

service is provided. For example, in the case of handover

and assuming that a certain multicast service is offered in the

target cell, it should be possible for the user to continue the

session in the target cell. It is possible that data loss will

occur due to user mobility. If the service is not available in

the neighbouring cell towards the user is moving, he should

be informed of that. Research is needed to investigate how to

realize the handover and to propose improved RRM

schemes.


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8) Dynamic Feedback for MBMS Common ChannelsThe introduction of MBMS provides multimedia services

to a large number of subscribers. The main barrier is the

inability of FACH to deliver MBMS services efficiently to

its multicast groups. The proposed power control algorithm

aims at overcoming the shortfall of FACH by improving on

its power transmission efficiency. The traditional FACH was

not created to deliver multimedia services to UEs. FACH

must be recognized differently as a new common channel

together with the proposed power control algorithm, which

aims at efficiently reducing transmission power in order to

efficiently utilize the available band-width. MBMS

Optimized Transmission Schemes

9) Non-Uniform Hierarchical ModulationIn a wireless communication network, depending on the

link conditions in broadcast and multicast transmissions,

some receivers will experience a better signal-to-

interference-and-noise ratio (SINR) than others, and thus the

capacity of the communication link for these users is higher.

A very simple method to improve the efficiency of thenetwork is to use hierarchical signal constellations (also

called embedded or multi-resolution constellations) which

are able to provide unequal bit error protection. In this type

of constellations there are two or more classes of bits with

different error protection, to which different streams of

information can be mapped. Depending on the propagation

conditions, a given user can attempt to demodulate only the

more protected bits or also the other bits that carry the

additional information. By using non-uniformly spaced

signal points, it is possible to modify the different error

protection levels. Depending on the UE position in the cell,

the users will demodulate the received signals either as 64-QAM (being discussed for HSPA+), 16-QAM, or QPSK.

These techniques are interesting for applications where

the data being transmitted is scalable, and can be split in

classes of different importance. In the case of video

transmission, for example, the data from the video source

encoders may not be equally important. The same happens

in the transmission of coded voice.

10) QoS Differentiation & Multi-Resolution BroadcastSharing channels is one of the most important aspects in

network optimization.

In scalable media, a base layer can be provided to satisfy

minimum requirements, and one or more enhancement layers

can offer improved qualities at increasing bit/frame rates and

resolutions. This method significantly decreases the storage

costs of the content provider and enlarges the effective

MBMS coverage area.

Common scalability options are temporal scalability,

spatial scalability and SNR scalability. Spatial scalability

and SNR scalability are closely related, with the difference

of an increased spatial resolution provided by spatial

scalability.

SNR scalability implies the creation of multi rate bit

streams. It allows for the recovery of coding errors, or the

difference between an original picture and its reconstruction.

Spatial scalability allows for the creation of multi-resolution

bit streams to meet varying display requirements and

constraints for a wide range of clients. It is essentially the

same as SNR scalability, except that a spatial enhancement

layer here attempts to recover the coding loss between an

up-sampled version of the reconstructed reference layer

picture and a higher resolution version of the original

picture.

B. Repeating Strategies & Ad-hoc NetworksNew topological approaches like multi-hop solutions and

repeating allow for an increased coverage of high rate data

transmission. Repeating can provide path loss savings and

can take advantages of the spatial diversity and the broadcast

nature of wireless networks. This will also allow for

delivering high data rate multicast content like MBMS to

large and spatially distributed user groups. The relatively

small regions covered by repeaters allow for reduced

transmitting powers with accordingly reduced interference.

The objective of this activity is to increase coverage for

high data rate transmission by covering remote areas and to

enable high data rate transmission for nearby but shadowed

areas. This enhancement of the region with high data rate

reception could be realized stepwise and also temporarily by

installing repeaters at locations where there is a special need.

Repeaters can act as gap fillers for shadowed locations

(e.g. inside of buildings). It has to be investigated whether

repeater networks can benefit from macro-diversity.

Especially, this could be the case with OFDM.

Strategies and algorithms for adaptive repeating could

extend the high data rate coverage with minimal additional

interference. The repeaters in a communication system could

possibly be used to deploy cells with dynamically

configurable sizes and forms, allowing for adapting the cell

structure to the user distribution and demand for high data

rate services.

C. Exploitation of Location InformationAs mentioned above, efficient mechanisms to switch from

ptp to ptm and vice-versa should be researched. Positioning

information can further be used to guide the setup of a ptm

radio bearer to serve a group of users close to the base

station and a ptp bearer for a single user at the cell border.

In addition, the exploitation of location information

should be investigated to trigger a handover at optimal

positions so as to make the most use of the base station

transmit power when the UE is moving from a ptm cell to a

ptp cell and vice versa. This work item is fostered by the factthat mobile terminals are expected to support GPS (or

assisted GPS) in the future.

D. MBMS Mobility ManagementA further research topic is the examination of the

interaction of mobility procedures and MBMS to identify

and better understand major limitations and key issues that

may influence the performance of the MBMS feature, and to

anticipate eventual problems in its deployment. Concerning

interaction of MBMS support with existing mobility

procedures, it will be important from an operator point of

view (especially in an initial deployment phase) that areaswhere MBMS is deployed may coexist with areas where

MBMS is not yet available.


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E. Receiver Baseband EnhancementsResearch might consider but will not be limited to the

techniques presented below.

1) Interference CancellationThe use of interference cancellation schemes (here the

term interference is used in a broad sense, including

multiple-access interference, inter-symbol interference,

inter-antenna interference, etc.) allows significantperformance improvements in most cases.

Interference cancellation schemes can be implemented in

a linear or iterative way and eventually combined with

iterative channel decoding. Intelligent schemes that trade

receiver performance vs. complexity would be of particular

interest. In general, interference cancellation will be

beneficial for both WCDMA based systems and LTE.

2) UE Receive DiversityC-MOBILE will consider the performance of receive

diversity on MBMS as an option, in the course of

developing new features.3) Advanced Decision-Directed Channel Estimation

In wireless communications, the mobile propagation

conditions lead to channels that distort the amplitude and

phase of the transmitted signal. This distortion has to be

estimated and tracked when performing coherent detection

in the receiver. An alternative are systems employing non-

coherent detection, but this incurs significant performance

degradation. Therefore, most of the mobile communications

systems employ coherent detection and require that the

amplitude and phase distortions caused by the channel have

been correctly estimated. A common technique for obtaining

estimates of the channel response is the transmission of pilotsymbols along with the data. However, channel estimation

can be a complicated task due to:

the pilot symbols being severely affected by noise and

interference

the number of pilots in a frame being limited (to avoid

a substantial loss of data rate)

the power spent on the transmission of pilots being

kept at a low level

To compensate for these limitations, advanced receiver

configurations are suggested, based on the turbo-processing

concept. Channel estimation requirements are especially

higher for large non-uniform constellations and/or multi-antenna scenarios.

F. Transmitter Baseband Enhancements1) Advanced FEC Mechanism

In this working item, we may study the use of advanced

coding schemes for scalable media applications and

hierarchical coding and modulation. Raptor codes would be

an interesting option.

2) Macro Diversity & Soft CombiningIn the downlink, two main cases of macro-diversity can be

distinguished, depending on whether the base stations aresynchronized or not. In the synchronized case, the user can

employ a single receiver to demodulate the superimposed

signals. This makes it possible to realize a particular

structure known as Single Frequency Network (SFN). With

macro diversity, the diversity gain increases, but these

benefits are sensitive to temporal synchronisation. In fact, in

order to avoid interference between OFDM symbols, the

cyclic prefix is usually longer than or equal to the maximum

time spread of the multipath fading channel.

When the base stations cannot be assumed to be

synchronized, different receiver chains will be needed to

demodulate the signals from the distinct base stations. This

is still very complex. The technique of macro-diversity can

also be used by selecting the best cell base-station in terms

of the path-loss and shadowing (selection combining), in

order to further mitigate the adverse effects of interference.

3) Space-Time/Space-Frequency Coding &Beamforming

We can use multiple transmit/receive antennas to improve

the diversity. However, it is more interesting to use the

multiple antennas to increase the data rate, while maintaining

(or even improving) the power requirements. An issue that

has to be considered with these techniques is the increasedreceiver complexity and the fact that the correlation between

antennas should be relatively low.

Depending on the availability/quality of channel state

information (CSI) at the base station, the downlink data rate

can be improved by either open-loop or closed-loop spatial

multiplexing, in the form of Space-Time Coding (STC) or

transmit beamforming. In addition, OFDM-based systems as

discussed for LTE further allow for the use of Space-

Frequency Coding (SFC). While STC does not require

knowledge of the downlink CSI, beamforming can exploit

partial or full knowledge about the channel, in order to

improve the receiver SNR and therewith the data rate. Aninteresting solution is a hybrid scheme adapting to the CSI

quality.

While beamforming is well-studied for point-to-point

(ptp) links, fewer and quite recent results are available for

multicast beamforming on point-to-multipoint (ptm) links.

The differences are the following.

Typically, beamforming schemes for multicast are

designed in a way such as to maximize the minimum

receiver SNR among all users belonging to a certain

multicast group, in order to optimize for the minimum

achievable QoS. However, the group size plays an important

role in such an optimization.As it has been shown recently, the multicast capacity goes

to zero as the number of multicast user tends to be large. The

same argument applies to the special cases of multicast

beamforming and open-loop STC, where the latter does not

require transmit-side CSI and is, by construction, capable of

supporting multicast users.

Such as efficient ptp-ptm switching can help to improve

the total system throughput, also an advanced spatial

processing at the transmitter which adapts to the group size,

user location profile, and channel conditions of the multicast

users can be highly beneficial.

Although the multicast capacity which concentrates on theworst-case user goes to zero as the group size becomes

large, the good-case users could actually achieve a much

higher data rate and service quality. Non-uniform


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hierarchical signal constellations are capable of adapting to

different channel conditions and providing different QoS

levels to the multicast users. Together with advanced spatial

processing at the transmitter, they are an effective means of

increasing the overall throughput.

4) Optimized Pilot InformationFor performing coherent detection at the receiver, it is

necessary that the amplitude and phase distortions caused bythe channel are correctly estimated. With this aim, pilot

symbols known by the receiver are usually transmitted along

with the data. The receiver performance will depend on the

channel estimation quality, which in turn depends indirectly

on the pilot structure. Therefore, several modes of pilot

transmissions together with advanced receiver

configurations (capable of enhanced channel estimation)

should be evaluated.

IV. CONCLUSION

Mobile broadcast services are attractive for mobile users and

offer new service opportunities for mobile operators. Inorder to efficiently support mobile broadcast services, 3GPP

has standardised Multimedia Broadcast Multicast Services in

UMTS Release 6. This paper identifies RAN enhancements

for MBMS support in current and future system. The C-

Mobile project investigates three reference systems. First,

systems based on WCDMA technology as they have been

already deployed or follow the evolution tracks in 3GPP.

Secondly, LTE (Long-Term Evolution) compatible systems

based on OFDMA and SC-FDE access technology will be

addressed. Finally, so-called future systems whose network

topology and access technology is open and that allow for

new concepts will also be studied. Research projects, such as

C-Mobile, are ensuring the evolutionary roadmap of MBMS.

REFERENCES

[1] M. Bakhuizen, U. Horn: Mobile Broadcast/Multi-cast in MobileNetworks, Ericsson White Paper, 2005

[2] R. Tnjes, U. Horn, F. Hartung: Business and TechnologyChallenges for Mobile Broadcast Services in 3G, 12th WWRF

Wireless World Research Forum, Toronto, 4-5 November, 2004.

[3] TS 23.246, Multimedia Broadcast/Multicast Service (MBMS);Architecture and functional description

[4] 3GPP TS 25.346 Introduction of the MBMS in the Radio AccessNetwork (RAN)

[5] C-MOBILE Deliverable D3.1 Research Directions and TechnologyRoadmap for RAN, June 2006.

[6] C-MOBILE Project Website: http://c-mobile.ptinovacao.pt/

Documents

1- RAN Enhancements for Advanced MBMS