mobile broadband system evolution towards 5g: lte · pdf filelte advanced: targets carrier...

Mobile broadband system evolution towards 5G: LTE-Advanced Release 10, Release 11, Release 12, Release 13

Romeo GiulianoDepartment of Innovation & Information EngineeringGuglielmo Marconi [email protected]

mailto:[email protected]

Topics

LTE introduction

Market trends

LTE description: Release 8 and Release 9

Architecture, Access technique and frame structure, Physical layer

LTE Advanced: targets

Carrier Aggregation (CA)

Multiple Input Multiple Output (MIMO)

Heterogeneous Network and small cells

Home eNodeB (HeNB) or femtocells

Inter-Cell Interference Cancellation (ICIC)

Coordinated Multi-Point (CoMP) Transmission and Reception

Enhanced Physical Downlink Physical Control Channel (EPDCCH)

Self-Optimizing Network (SON) hints

Signaling and Procedure for Interference Avoidance for In-Device Coexistence

Machine Type Communications (MTC)

Proximity Services

Public Safety

Selected IP Traffic Offloading (SIPTO)

Summary functionalities in Releases

Other functionalities in Release 11


LTE-A for 5G: What is 5G, 5G requirements, 4G enhancements for 5G, Potential technologies for 5G

Conclusions towards 5G, References

2

LTE: key features

High spectral efficiency: OFDM (Robust against multipath interference, High affinity to advanced techniques as MIMO and frequency scheduling), Single�Carrier FDMA (Low PAPR, User orthogonality in frequency domain), applicability of Multi�antenna

Very low latency: Short setup time & Short transfer delay, Short

HO latency, Short TTI

Support of variable bandwidth: 1.4, 3, 5, 10, 15 and 20 MHz

Simple protocol architecture: Shared channel based, PS mode only

(but with VoIP capability

Simple Architecture: eNB and S1/X2 interfaces

Compatibility and inter�working with earlier 3GPP Releases and with other systems, e.g. cdma2000

FDD and TDD within a single radio access technology

Efficient Multicast/Broadcast: Single frequency network by OFDM

Support of Self�Organising Network (SON) operation

3

Global Market Share for LTE and HSPA+ Mobile Broadband

4

Mobile Broadband Coverage Reach, 2009-2020

5

Global Mobile Technology Shares: Q4 2014 – Forecast Q4 2019

6

7.1 Billion Subscriptions 8.4 Billion Subscriptions

Global Mobile Data Traffic 2014 to 2019

Increased data usage due to:

The amount of available content and applications

The improved network speeds that come with HSPA and LTE development (improving the user experience)

By 2017, data traffic using 4G will cover more than half of all mobile traffic used

In 2013, total mobile traffic generated by mobile phones exceeded that from mobile PCs, tablets and mobile routers for the first time.

In 2014, mobile data traffic was nearly 30 times the size of the entire global internet in 2000

7

Compound annual growth rate (CAGR)

Global Growth for M2M

Global Mobile Device Growth by Type

Cellular M2M connections forecast scenarios (millions)

8

Bill

ion

of M

obile

-Con

nect

ed D

evic

es

Worldwide revenue from smart city technology will grow from $8.8 billion in 2014 to $27.6 billion in 2023

LTE TDD and FDD Bands

9

LTE standardization

LTE (up to 300 Mbit/s)

Release 8: basic version, SON self-configuration

Release 9: SON self-optimization, important enhancements, such as position location technologies, in different areas to cover for the requirements for emergency call.

LTE-Advanced

Release 10:

Carrier aggregation up to 40MHz total band, and later potentially up to 100 MHz;

MIMO evolution up to 8 ×

8 in downlink and 4 ×

4 in uplink;

Relay nodes for providing simple transmission solution;

Heterogeneous networks for optimized interworking between cell layers including macro, micro, pico and femto cells.

SON self-optimization and SON self-healing; Local IP Access (LIPA)

LTE-Advanced

Release 11: Cooperative Multipoint Transmission (CoMP), Home-eNode B,

Release 12: 2D antennas, Dual Connectivity, Proximity Service, Public Safety, Selected IP Traffic Offload (SIPTO), Wi-Fi integration

Release 13: CA up to 640 MHz, MTC enhancements, inter-site CoMP

10

LTE description: release 8

Architecture

Access technique

Physical layer

Uplink transmission

Downlink transmission

Terminal capabilities

11

Architettura del sistema LTE

Evolved Packet Core Network (EPC)

Serving Gateway (S-GW)

Packet Data Network Gateway (P-GW)

Mobility Management Entity (MME)

Home Subscriber Server (HSS)

Policy and Charging Rules Function (PCRF)

Evolved UTRAN

eNode BEvolved Packet System (EPS) tutti i

servizi sono offerti su IPDati (linee continue)Controllo (linee tratteggiate)

12

Accesso multiplo nel sistema LTE

A differenza del sistema WCDMA, il sistema LTE usa una tecnica di accesso multiplo basata sulla modulazione Orthogonal Frequency Division Multiplexing (OFDM).

In downlink, tratta da uno a molti (si parla di multiplazione), si usa la versione di base dell’OFDM [in alcuni libri è

chiamata OFD Multiple Access]: gli utenti sono individuati assegnando ad ognuno di essi sottoportanti differenti

In uplink, tratta da molti ad uno (si parla di accesso multiplo), si usa il Single Carrier –

Frequency Division Multiple Access (SC-FDMA)

Queste tecniche di accesso si basano sull’ortogonalità

degli utenti riduzione dell’interferenza incremento capacità

di rete

La risoluzione nell’allocazione delle risorse in frequenza è

12 sottoportanti di 15 kHz ciascuna per un totale di 180

kHz: blocco assegnato in uplink e in downlink

In uplink sottoportanti contigue perla trasmissione Single Carrier

In downlink sottoportanti scelteliberamente e assegnate ai vari utenti

NOTA. Single Carrier proposta per la prima volta nel sistema LTE: risolve il problema degli amplificatori di potenza nei dispositivi mobili

13

Accesso multiplo (2): allocazione risorse

Esempio di allocazione delle risorse in downlink con prefisso ciclico breve

Ottimizzazione della trasmissione: nel tempo, favoriti gli utenti con bassa attenuazione del fast fading; in frequenza, eliminate le sottoportanti su cui agisce la selettività

del canale

Modulazione uguale su base blocco di risorse

14

Strato fisico: trasmissione dati in uplink

La trasmissione dati d’utente avviene sul Physical Uplink Shared Channel (PUSCH)

Durata di trama: 10ms

Allocazione delle risorse su base tempo –

frequenza

Risoluzione di 1 ms in tempo e 180

kHz in frequenza

Lo scheduler nel eNode B definisce l’allocazione delle risorse

Nell’LTE non ci sono risorse dedicate agli utenti

Gli utenti possono trasmettere solo se schedulati dall’eNode B o sui canali di accesso casuale

Gli UE devono riportare all’eNode B lo statodel proprio buffer dati e la potenza disponibile

15

Strato fisico (2): trasmissione dati in downlink

Trasmissione dati d’utente in downlink avviene sul Physical Downlink Shared Channel (PDSCH)

Risoluzione risorse: 1 ms nel tempo e 12 sottoportanti (180

kHz) in frequenza

blocco tempo –

frequenza: Physical Resource Block (PRB)

OFDM per separare i flussi degli utenti (multiplazione e non accesso multiplo) bit rate istantaneo dell’utente dipende da quante sottoportanti ha allocate (15

kHz ciascuna)

Allocazione in tempo e in frequenza è

eseguita dall’eNode B in base ai CQI trasmessi dai terminali (figura)

L’allocazione delle risorse ètrasportata dal Physical Downlink Control Channel che indica ai terminali quale sottoportante èallocata ad ognuno di essi

16

Strato fisico (3): trasmissione dati in downlink

Struttura di trama (figura a sinistra): durata è

10

ms; composta da 10 sottotrame di 1

ms

Ogni sottotrama ha due slot di 0.5 ms ciascuno

Nello slot 7 simboli (per prefisso ciclico breve) o 6 simboli (per prefisso ciclico lungo)

Physical Control Format Indicator Channel (PCFICH) indica il formato del PDCCH

Physical Downlink Control Channel (PDCCH) indica l’allocazione dei dati per gli utenti: da 1 a 3 simboli; simboli restanti per il PDSCH

Physical Downlink Shared Channel (PDSCH) trasporta: dati d’utente, dati di broadcast e reference signal (figura a destra)

17

Categorie dispositivi LTE Rel-8

Capabilities per terminali LTE divise in 5 categorie

Categorie definite nelle Release 8 e Release 9 variazioni dovute agli sviluppi futuri previsti nella Release 10 (nuove funzionalità

dell’LTE Advanced)

Notevole incremento tra la categoria 1 e 2: argomento nel 3GPP forum

Ricezione multi antenna in dispositivi piccole dimensioni limitato guadagno soprattutto per frequenze inferiori ad 1

GHz

18

LTE-Advanced: Release 10

Objectives:

Increased peak data rate, DL 3 Gbps, UL 1.5 Gbps

Higher spectral efficiency, from a maximum of 16bps/Hz in R8 to 30 bps/Hz in R10

Increased number of simultaneously active subscribers

Improved performance at cell edges, e.g. for DL 2x2 MIMO at least 2.40 bps/Hz/cell.

Added functionalities

Carrier aggregation

Multiple Input Multiple Output

Relay nodes

Coodinated Multi-Points

19

Carrier Aggregation (CA)

Principle: to extend the maximum bandwidth in the uplink and downlink by aggregating multiple carriers.

The carriers to be aggregated are basically Release 8 carriers, necessary for backwards compatibility

Envisaged bands: 800 MHz, 1800 MHz, 2600 MHz

20PCC = Primary Component CarrierSCC = Secondary Component Carrier

CA: bands for aggregation

In downlink support the intra and inter-band CA: usually each operator does not have more than 20MHz in a given frequency band

In uplink, CA is not attractive: the use of two transmitters simultaneously in the UE is more challenging than two receivers further studies in Rel-11

21

CA: impacts

CA affects the physical layer and the MAC layer: It is unchanged the user plane layers above the MAC and at the core network (except higher data rates).

The MAC layer divides the data between different component carriers: no limitation by multiplexing functionality on the component carriers (CC)

The CA affects the feedback in uplink

Difficult to use DTX in uplink (necessary for feedback) since it

causes a spectrum with spikes

The power can be an issue (spread over the bands) and amplifier in linear region

22

CA: changes in uplink

In uplink, necessity to provide feedback for multiple carriers (e.g. ACK/NACK multiple packets received in the downlink aggregated carriers) as well as CQI/CSI/PMI

HARQ and channel state information (CSI) feedback signaling need to be tailored to support up to five CCs

Up to 10 ACK/NACK bits can be signaled simultaneously

(Rel-10)

CSI feedback is a straightforward extension of the Release-8 principles and mechanisms by copying them for multiple component carriers.

Power control

PUSCH on each uplink component carrier are power controlled independently: power control is carrier specific

PUCCH has an independent power control.

Possible scale down in order not to exceed the maximum transmitting power or prioritization (PUCCH has the highest priority and PUSCH with uplink control information has the second highest priority)

23

CA: changes in downlink

The key adjustment is in the related signaling as the UE now needs to obtain information about allocations on all the component carriers that it is able to receive.

Changing in the format of PDCCH: cross-carrier scheduling.

The eNodeB may provide information, using the PDCCH (UE specific search space), about any of the carriers indicating that there is data on another carrier

Introduction of the Carrier Information Field (CIF), that indicates, which component carrier is in the downlink scheduling.

24

CA: mobility

Only one RRC connection when CA is activated: different carriers do not operate independently.

The serving cell handling the RRC connection is the Primary Serving Cell (PCell).

Configuration of other SCells based on the UE’s capabilities.

Mobility is based on the PCell measurements

Possible connection re-establishment is triggered when the PCell has a radio link failure (RLF).

A RLF on a SCell does not cause re-establishment.

UE can also provide information about the best non-serving cell on another frequency.

Support of backwards compatibility (other frequency bands are considered as a handover in Rel-8) and deployment of CA selectively in the network, without upgrading all the eNodeBs in the coverage area.

25

SCells can be added or removed depending on the available resources in the target cell

The source cell can provide information about which cell would be suitable as the SCell based the UE measurements on radio conditions.

The target cell, together with the handover command, can then reconfigure the UE to drop the SCells if CA is not required to be used. This may be due to load reasons or when moving to a cell not supporting CA,

CA: improvements

Increased peak data rate with CA

Theoretical peak data rate up to 1.2 Gbps in downlink and up to 600 Mbps in uplink with the use of MIMO for a total of 40MHz spectrum

Theoretical peak data rate up to 3 Gbps in the downlink and 1.5 Gbps in the uplink with 100MHz (five aggregated carriers)

Improved average user throughput, especially when the number of users is not too high.

Joint carrier scheduling in the eNodeB allows the optimal selection (in a dynamic fashion) of the carrier to use thus leading to better performance and optimal load balancing between the carriers

26

CA: enhancements in Rel-11

Multiple Timing Adjustments Groups (TAGs)

Multiple timing advances in UE different for each component carrier: presence of RRH, small cells, relays,…

Rel-11 essentially includes new enhancements in CA that will support non-collocated cells.

Possible TAGs are grouped if UE measures the same TA value

If the Timing Advance Group contains the PCell, then it is called as Primary Timing Advance Group (pTAG).

If the Timing Advance Group contains only the SCell(s), then it is called as Secondary Timing Advance Group (sTAG)

TAGs are configured by RRC up to 4 TAGs

For pTAG, UE performs RACH to obtain synchronization

For sTAG, non-contention RACH is performed upon reception of the PDCCH order from eNB. First access is similar to Timing Advance procedure in Rel-8

27

CA: enhancements in Rel-13

CA is extended up to 32 carriers

New control signaling should be specified for 32 component carriers

Changes in feed back

The LTE terminals is able to handle bandwidth up to 640 MHz (part in unlicensed spectrum)

28


Key technology in the LTE Release 8: Transmission modes for one, two and four eNodeB antenna ports have been specified providing peak data rates in excess of 300 Mbps

Advances in the LTE-Advanced

Downlink transmission with up to eight transmit antenna ports peak spectral efficiency increases up to 30 bps/Hz corresponding to 600 Mbps on a 20MHz carrier

Introduction of Multi-User MIMO (MU-MIMO) operation. Multi-User MIMO refers to the transmission where the parallel streams are transmitted to different UEs separated spatially while in Single-User MIMO (SU-MIMO) the parallel streams are sent to single UE.

29

MIMO: basic principle

Nt

tx antennas, quasi-static channel (i.e. Tb

Tcoh

), Nr

rx antennas

H is the Nr

× Nt

channel matrix with whose entries hij are complex channel gains (transfer functions) from the j-th transmit to the i-th receive antenna.

The received signal vector: r = Hs + n = x + n contains the signals received by Nr

antenna elements, where s is the transmit signal vector and n is the noise vector.

Consider a singular value decomposition of the channel: H = WU†, where

is a diagonal matrix containing singular values, and W and U†

are unitary matrices composed of the left and right singular vectors, respectively.

30

The received signal is: r = Hs + n = WU†s + n

Multiplication of the transmit data vector by matrix U and the received signal vector by W†

diagonalizes the channel: W†r = W†WU†Us + W†n; r’ = s +n’

RH

(rank of matrix H) parallel channels (eigenmodes of the channel) the capacity of parallel channels just adds up.

(.)†

= ((.)T)*

MIMO: enhancements in Rel-10

The MIMO needs of reference symbols (RSs) to estimate the channel and apply the matrix inversion

In Rel-8, Rel-9 the MIMO operation is primarily based on cell-specific Common Reference Symbols (CRS) used both for Channel State Information (CSI) measurements as well as the data demodulation

In Rel-10, it is defined another RS pattern to increase the number of antennas:

Issues: backwards compatibility; High RS overhead

Basic idea: to decouple RSs for CSI measurements (namely CSI-RS used for CQI, PMI, RI, with lower and adaptable periodicity (from 5 to 80 ms)) and fordata demodulation (user-specific and dedicated, URS or DM-RS), which are flexible, adapted to the rank of the users

31

MIMO: example of Reference Signals for 8 ports

32

MIMO: long-term and short-term

The LTE Release-10 support both downlink SU-MIMO and MU-MIMO. The choice is dependent of the scenario:

SU-MIMO is more effective for less correlated scenarios with higher channel azimuth (i.e. angular) spread

MU-MIMO is typical for highly correlated scenarios with a small azimuth spread.

Dynamic switching between SU-

and MU-MIMO based on scenario (correlated fading), traffic load, multi-user diversity. Changes on TTI basis

Decoupling the long-

and short-term CSI components: adoption of a double codebook structure for CSI feedback

The precoder W for a sub-band is composed of two matricesbelonging to two distinct codebooks: W1 targets the long-term wideband channel properties while W2 aims at short-term frequency selective CSI, i.e. W = W1 ×

W2

The feedback rate for the W1 and W2 can be different, allowing for minimized uplink signaling overhead.

33

MIMO: Single User and Multiple Users

34

MIMO: summary

Enhancements in MIMO are provided by defining new different Transmission Modes (TM)

The UE will through RRC signalling be informed about the transmission mode to use

In the DL there are nine different transmission modes, where TM1-7 were introduced in R8, TM8 was introduced in R9 and TM9 was introduced in R10

In the UL there are TM1 and TM2, where TM1, the default, was introduced in R8 and TM2 was introduced in R10.

The different transmission modes differ in:

Number of layers (streams, or rank)

Antenna ports used

Type of reference signal, Cell-specific Reference Signal (CRS) or Demodulation Reference Signal (DM-RS), introduced in R10.

Precoding type

35From 3GPP site

MIMO: enhancements in Rel-12 and Rel-13

Optimizations of codewords

Periodic and aperiodic transmission of CSI

Introduction of codewords for cross-polarization

Two-dimensional antennas for 3D fading scenarios

36

Heterogeneous Network (HetNet)

The need to provide a greater amount of data for a large number of subscribers forced the investigation of exploring the cell size

The capacity demand is not expected to be uniform, the cell sizes vary drastically

Macro cells in areas of less demand

Need of enhancing capacity with smaller cells in densely populated areas: from macro cell level down to micro and pico cells, and in some cases even to femto cells

The relay nodes form an additional dimension

In a heterogeneous deployment, the UE should be able to connect different types of cells from the link budget perspective

37

HetNet (2): BS categories

38

HetNet (3)

No interference with different cell types, if different frequencies are allocated for different types of cell and powers are not too high

With the increased capacity demand and consequently frequency request, the same frequency needs to be used with different types of cells interference issues

Countermeasures in 3GPP: Enhanced Inter-Cell Interference Coordination (eICIC) try to mitigate the interference by more effect power control or dividing the resources partly with the time domain element between different types of cell.

Coordination in X2 signaling through Almost Blank Subframe (ABS). Need of a common timing.

39

Small cells: enhancements in Rel-12

Physical layer

Good channel quality allows to support 256-QAM for PDSCH and PMCH

A new CQI table is needed: QPSK is substituted with 256-QAM entries

New terminal categories is needed: cat.13 (4Gbit/s with 5 CA and 8x8MIMO), cat.11 and cat.12 (600 Mbit/s, similar to cat.9 and cat.10 with 4 CA plus 256-QAM), cat.14 e cat.15 (similar to cat.6 and cat.7 plus 256-

QAM)

Other functionalities (studied but not standardized)

Reduction of reference signals: the fading channel for small cell is low frequency-selective and slow time-

variant

Cross subframe scheduling: eliminating the control signal in some subframes and using the multi-frame scheduling trade-off with scheduling flexibility

40

Small cell cluster with macro cell coverage (scenario 2): Use of cross carrier scheduling to facilitate the small cell deployment

Small cells (2): enhancements in Rel-12

Mechanisms for efficient operation in small cells: interference mitigation for non-

uniform small cell deployment

Small cell ON/OFF: the small cell with low traffic can be turned

off to reduce interference to the neighboring cells

Criteria for switching off: load traffic, UE arrival,…

Once switched off how can the cell be discovered by an UE?

Discovery signals and discovery procedure: designed to facilitate the cell detection of small cells even during their OFF state.

Introduction of new Discovery Reference Signals (DRS): the DRS consists of the Rel-8 Primary Synchronization Signal/Secondary Synchronization Signal (PSS/SSS) and Cell Specific Reference Symbol (i.e. Common RS) signals.

The DRS-based RRM measurement reports are sent by UEs to the serving cell as the reference for the network to decide whether the switching-OFF small cell should be turned ON.

Radio Interface Based Synchronization (RIBS): necessity to have synchronous LTE networks to better perform some functionalities (e.g. ICIC, CoMP). GPS is

not available indoor

Network listening and UE assisted synchronization: some Reference Signals are used for synchr.

41


Higher Layer Considerations: enhancements for mobility robustness, reduction of signaling load towards the Core Network (CN) due to handover and

improved per-

user throughput and system capacity.

Dual connectivity in Rel-12: a given UE is capable of using radio resources provided by two different network points connected with non-ideal backhaul

Mobility robustness: keeping the control plane termination in a macro node, while allowing offloading of user plane traffic to pico nodes within the macro coverage potential handover issues for pico handovers can be avoided.

Inter-node radio resource aggregation: radio resources from more than one eNB are aggregated for user plane data transmission to achieve

per-user throughput enhancements (figure).

Dual connectivity consists of configuring a UE with one Master Evolved NodeB (MeNB) and one Secondary Evolved NodeB (SeNB): signaling overhead towards the CN can potentially be saved

42


Protocol plane

MeNB Cell Group (MCG) bearer –

the bearer is served using radio resources of MeNB only

SeNB Cell Group (SCG) bearer –

the bearer is served using radio resources of SeNB only

Split bearer –

the bearer is served using radio resources from both MeNB and SeNB

Signaling Radio Bearers (SRBs) are always of the MCG bearer and therefore only use the radio resources provided by the MeNB.

43User Plane protocol architecture for Option 2

Femto cells

Femto cells are indoor or office base stations (paid by the customers)

Low power home, low cost, simple installation (connected to operator network by the subscriber DSL modem)

Aim: to improve the indoor coverage for smartphones, macro BS offload

High femto number, connected to a gateway (hiding issues and scalability)

Femto cells use the operator’s licensed frequencies

Same as macro cell frequency (co-channel interference countermeasures should be taken (e.g. power control)) or a dedicated frequency.

The mobility between macro and femto cells needs to be considered in

order to provide a seamless end-user experience.

44

Femto cells: subscriber groups and handovers

Closed Subscriber Group (CSG) HNB: the cell can be accessed only by the members of the cell group: restrict usage of the service (not public coverage for the operator)

Hybrid HNB: part of the capacity is ‘reserved’

for the UE belonging to the configured CSG, but a part of the capacity is left open for more public usage: service differentiation for the CSG membership

Open HNB: fully open access to all subscribers, hot-spot as part of the managed WAN. It is like a normal macro cell.

45

Femto mobility solutions for uncoordinated deployment for HSPA+

Femto cells: practical deployment

The supported features may be different in femto and macro cells: different hardware and software platforms for femto cells.

The data rates in femto cells may be limited by the DSL backhaul

Femtocells deployment is subscriber care: the frequency assigned

to the femto takes part of the macro capacity, difficulties in joint deployment

Different location areas (LAI) are used in macro and femto cells. Location Update (LU) should performed carefully (lost of paging messages)

The maximum number of users is typically limited in femto cells, which may cause problems if using femto cells in large enterprises or in public premises.

The femto and macro cells are typically provided by different vendors and the corresponding operability tools are also different.

The femto cell adds co-channel interference, which may impact those UEs that are in weak macro signal and are not able to connect to CSG femto cells.

(for HSPA) Soft handovers are typically not available between co-channel femto and macro cells: impact on the mobility.

field experience: femto cells good in indoor (for offloading and enhancing indoor capacity); more problems for outdoor deployment (backhaul, more Tx power, higher capacity need, high mobility)

46

Home eNodeB (HeNB)

In LTE Rel-10, X2 handover involving HeNBs was only possible between two HeNBs and when either the two HeNBs were operating in closed/hybrid access mode with the same CSG ID, or the target HeNB was operating in open access mode.

47

HeNB: enhancements in Release 11

Changes in HeNB in Rel-11

Adding on the X2 interface with other (H)eNBs.

Additional functionalities respect to legacy eNB

The HeNB will not simultaneously connect to another HeNB GW, or another MME.

Selection of an MME at UE attachment is hosted by the HeNB GW instead of the HeNB

HeNBs may be deployed without network planning. A HeNB may be moved from one geographical area to another and therefore it may need to connect to different HeNB GWs depending on its location;

A list of CSG IDs may be included in the PAGING message. If included, the HeNB GW may use the list of CSG IDs for paging optimization.

The HeNB may support the LIPA function (Local IP Access): S5 interface

48

HeNB: handover/mobility in Release 11

Release 11 handover involving scenarios. Added mobility cases are:

X2 handover from/to HeNB to/from macro eNB

Inter-CSG X2 handover towards hybrid HeNBs

49

Procedure for Inter-CSG X2 handover towards hybrid HeNBs

X2-based HO support


Issues: challenge in scalability

High number of (H)eNB

High number of triggered “neighbor address discovery S1 procedures”

and the number of SCTP associations to be supported by an eNB

Unlike eNBs, (H)eNBs under control of end users can experience frequent and/or unexpected switch-off and also peaks of switch-on signaling

IP address change due to the switch on/off also need to be addressed

Introduction of X2 GW (on X2 interface).

Functionalities: support routing, support the signaling info, addresses’

mapping

Backwards compatible: a (H)eNB can connect to a peer (H)eNB using either direct X2 or via the X2GW

50


Mobility to a target eNB shared by multiple operators

Issue: the target PLMN selected must be compatible with the UE in terms of Closed Subscriber Group (CSG) membership when that (H)eNB is hybrid/closed

The UE can be a member of the CSG for PLMN1 but not for PLMN2.

In 3GPP Rel-12, the mobility procedures for UEs are enhanced with a new capability of reading and reporting to the source eNB, prior to the handover decision

In Rel-12, when receiving this new list and deciding to trigger the handover, the source eNB is also enhanced with the capability of selecting one of those PLMNs while verifying that it actually is an equivalent PLMN or the serving PLMN.

The MME verify that the UE is

Actually a member of the CSG for the PLMN eventually selected by the source eNB

Allowed for this handover.

51

TA: Tracking Area

Inter-Cell Interference Coordination (ICIC)

Inter-Cell Interference Coordination involves the intelligent coordination of physical resources between various neighboring cells to reduce interference from one cell to another

Use of some resource in a coordinated fashion to improve performance especially for cell edge users, which are impacted the most by inter-cell interference.

The objective of SON is the self-configuration and self-optimization of control parameters of RRM ICIC schemes for uplink (UL) and downlink (DL) ICIC

ICIC requires that neighboring cells exchange information about which portion of the total bandwidth they are using

The core ICIC algorithms are those that determine how the resources (time, frequency and power) available are managed to realize interference coordination between the cells.

52

ICIC

Inverted Reuse scheme

Part of the spectrum is used with reduced power or not used

Cell-inner users and Cell-edge users

Aim: Concentrate the bulk of the inter-cell interference in a small portion of the total bandwidth, thereby preventing any impact to the majority of users since the interference is now localized to certain sub-carriers and the sub-carriers are orthogonal to each other.

53

ICIC

Potential interference scenarios between a Home eNB and a macro cell (figure up)

Rel-8, Rel-9 did not provide any control mechanisms between the HeNB and the macro base stations

Potential DL/UL interference between HeNB and macrocell

Weak in-home coverage

In UL, the non-allowed UE increases its power to be reached by macro cell, causing interference in the HeNB communications (figure down)

54

ICIC: enhanced ICIC (eICIC) in Rel-10, Rel-11

Time-domain solution –

Subframe utilization (Almost Blank Subframes, ABS) across nodes are coordinated through backhaul signalling.

Power control solution –

HeNB adjusts its transmit output power to avoid interference to other nodes.

Frequency-domain solution –

Orthogonal bandwidth for control signaling and common information are configured across nodes.

In Rel-11, further reduction of signaling in ABS, by using SIB-1 channel in PBCH: Further Heterogeneous Networks Enhancements (FeICIC)

55


Aim: to improve network performance at cell edges

Idea

of CoMP: depending on a UE’s location, it may be able to receive signals from multiple cell sites, and the UE’s transmissions may be received at multiple cell sites regardless of the system load, in a coordinated fashion

A TX/RX-point constitutes of a set of co-located TX/RX antennas providing coverage in the same sector. Several options:

The set of TX/RX-points can be at different locations

The set of TX/RX-points can be co-sited but providing coverage in different sectors

56

CoMP: scenarios

Work:

For the DL, the transmissions from the multiple cell sites can be coordinated

For the UL, the system can take advantage of reception at multiple cell sites (e.g., through techniques such as interference cancellation).

Scenarios:

Scenario 1: Homogeneous macro-cellular network with intra-site CoMP

Scenario 2: Homogeneous macro-cellular network with inter-site CoMP

Scenario 3: Heterogeneous network with CoMP operation between the macrocell and low power small cells within the macrocell coverage area, where the low power small cells have different cell IDs from the macro cell

Scenario 4: Heterogeneous network with low power RRHs within the macrocell coverage where the transmission/reception points created by the RRHs have

the same cell Identifications (IDs) as the macro cell

57

CoMP: three approaches

Coordinated Scheduling or Coordinated Beamforming (CS/CB),

The transmission to a single UE is transmitted from the serving cell only (same as in non-

CoMP transmission).

The scheduling and any Beamforming functionality are dynamically

coordinated between the cells in order to control and/or reduce the interference between transmissions from different transmission points.

Dynamic Point Selection (DPS)

The UE, at any one time, is being served by a single transmission point. But it can change dynamically from subframe to subframe within a set of possible transmission points

58CoMP with Joint Beamforming

CoMP: three approaches

Joint Processing/Joint Transmission (JP/JT).

The transmission to a single UE is simultaneously transmitted from multiple transmission points, across cell sites.

The multi-point transmissions coordinated as a single transmitter: higher performance but stringent requirement on backhaul communication

59

CoMP: enhancements in Rel-11

Definition of a new Physical Downlink Shared Channel (PDSCH) Transmission Mode 10 (TM10)

Common feedback and signaling framework, supporting CS/CB and DPS

Three CoMP measurement set: 1. feedback on non-zero-power Channel-State Information-

Reference Symbol (CSI-RS) resources, 2. zero power Channel-State Information Reference Symbol (CSI-RS) resources, and 3. interference measurement Channel-State Information-

Interference Measurement (CSI-IM) resources

In case of CS/CB, the UE’s CSI feedback provides

The Channel Quality Indications (CQI) and PMI (preferred precoder) for the serving cell’s transmissions to that UE

PMIs for other transmission points would indicate the precoders to be avoided by the other transmission points

In case of DPS,

Each CSI process provides the preferred CSI and PMI for a different transmission point

Dynamic downlink control signaling indicates the PDSCH rate matching and

resource-element mapping according to the selected transmission point in each subframe, starting OFDM symbol for the data in the subframe, and the locations of the zero-power CSI-RS.

Which CSI-RS the demodulation RS may be assumed to be “quasi-co-located.”

No explicit support is provided for JT in Rel-11

60


A centralized (master/slave) approach

The slave eNBs provide coordination information to a Centralized Coordination Function (CCF)

Issue: necessity to introduce a new node and a new interface to be defined/standardize

the benefit does not justify a new node/interface.

A distributed (peer to peer) approach

Each eNB exchanges coordination information with its neighbor in a cluster over the existing X2 interface

E.g. by utilizing existing messages (i.e., LOAD INFORMATION) over the X2 interface

distributed approach has been preferred over the centralized approach. But the standards shall not preclude centralized

61

Centralized Coordination

Function


Exchange of load information in the X2AP: LOAD INFORMATION message and resource allocation decisions based on the information provided by its neighbor

Any additional resource allocation decisions made by either eNB takes into account the information exchanged over X2 from their neighbors.

Exchange of Reference Signal Receiver Power (RSRP) measurement reports of individual UEs over X2 interface in the X2AP: RESOURCE STATUS UPDATE message.

Configurable reporting interval of 120ms, 240ms, 480ms or 640ms

62


In LTE Rel-8, three control channels in the downlink for subframe description:

Physical Control Format Indicator Channel (PCFICH), indicates the size of the downlink control region

Physical Downlink Control Channel (PDCCH), assigns downlink and uplink data resources

Physical Hybrid ARQ Indicator Channel (PHICH) provides acknowledgment for uplink transmission

Control region size is up to 3 OFDM symbols significantly limits the control capacity

Cross carrier scheduling in Carrier Aggregation (CA)

More performant transmission modes (as Multi-User MIMO and Cooperative Multipoint Transmission and Reception (CoMP)) allow to accommodate more users but higher control capacity can be required.

Same problem for deployment large number of terminal in a small bandwidth to provide Machine Type Communication (MTC)

Managing the interference in variegate and heterogeneous scenarios (with Small Cell) requires flexibility to have a better interference coordination.

Introduction of the EPDCCH in Rel-11

63

EPDCCH: characteristics

Improved control capacity

EPDCCH shares the same physical resource as PDSCH

Unlike PDCCH, EPDCCH is frequency division multiplexed with PDSCH.

EPDCCH is allowed to occupy as many PRB pairs as needed; trade-off between throughput/users maximization and control capacity

Flexible Resource Allocation

EPDCCH resource configuration is UE-specific.

The granularity allocation is 1 PRB (Physical Resource Block) greater flexibility than PDCCH (configured in terms of OFDM symbol).

Increased Spectral Efficiency

When reliable CSI feedback is available, EPDCCH is scheduled in the sub-

bands more favorable to the UE (localized transmission). MU-MIMO and beamforming can also be adopted.

Robustness

When reliable CSI feedback is not available (e.g. high UE mobility), EPDCCH resource is spread across a wide bandwidth to benefit from frequency diversity gain

(distributed transmission)64

SON enhancements in Rel-11

Automatic Neighbor Relations (ANR)

Load Balancing Optimization

Handover Optimization

Coverage and Capacity Optimization (CCO)

RACH optimization

Energy Saving

Minimization of Drive Tests

65

Signaling and Procedure for Interference Avoidance for In- Device Coexistence (IDC)

Aim: preventing coexistence interference between the radio transceivers of the different technologies that are co-located on the device

66

IDC: techniques in Rel-11

Exploiting the frequency separation between the different technology transceivers: signal filtering

FDM concept: move the LTE signal away from the Industrial, Scientific and Medical (ISM) band inter-frequency handover, or removing SCells from the set of serving cells

TDM concept: avoiding the LTE transmission when another signal is received and vice versa.

Exploiting the unscheduled periods of the UE to solve the IDC

The UE can autonomously deny LTE UL transmission to protect ISM transmission or deny ISM transmission in order to protect essential LTE signaling (e.g., RRC connection reconfiguration and paging reception).

67


Characteristics:

Communications involve little or no human interaction

Large number of devices

Periodic or intermittent access

Small amount of data per “session”

The number of connected MTC devices will outnumber the human-centric communication devices. Challenges in the standardization:

Support of low-cost and low-complexity device types to match low performance requirements (for example in peak data rates and delay) of certain MTC applications

Provide extended coverage for MTC devices in challenging locations

Enable very low energy consumptions to ensure long battery life

Serve very large numbers of devices per cell by optimizing signaling of small data transmission

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MTC (2): architecture

Interworking function MTC-IWF: provides security, charging and identifier translation (external-to-internal identifier)

MTC server (optional), MTC Application

Models: direct (Over-The-Top applications connects directly to MTC devices); indirect (MTC application connects through the MTC server –

additional value-

added services); hybrid (OTT connects directly but uses also value-added services)

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MTC (3): enhancement in Rel-11

Needs of a better control of signaling congestion and overloading of RAN due to MTC devices Extended Access Barring (EAB) is a mechanism, enabling the RAN (eNB) to bar (i.e. restrict) the access of one or several classes of UEs configured for EAB via new system information (dedicated for “EAB devices”).

The eNB can broadcast a new System Information Block (SIB) type (i.e. SIB 14), which includes:

An EAB Barring Bitmap: it is a 10-bit string enabling the indication of which Access Class (AC), numbered as 0-9 and stored in the SIM) is barred

If a bit is set, the corresponding AC is barred, for example “1010000000”

means AC0 and AC2 are barred.

A EAB Category: differentiation based on PLMN: UEs barred are

Category a: all UEs; Category b: UEs not in their Home-PLMN or in an Equivalent-PLMN; Category c: UEs not in a “most preferred”-PLMN

The MTC UE should monitor the changes in SIB-1 and SIB 14 to know any changes in UE barring

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Issue: low complexity devices and small data transfer (with inter-arrival time from several seconds to many hours) frequent (and inefficient) UE state changing. Solutions:

Low cost and extended coverage MTC UE

Reduced data rate with maximum Transport Block Size (TBS) of 1000 bits for unicast and 2216 bits for broadcast definition of a new UE category (cat.0).

Category 0 UE considers a cell incapable of supporting the low complexity

feature as a barred cell and should not camp on such cells.

UE Power Consumption Optimization (UEPCOP)

Power saving (or dormant) state, extended DRX cycle (both in IDLE and CONNECTED mode), detaching the UE (some completed in Rel-13)

(proposal on reduction of signaling on CN) SDDTE: Data over Non-Access Stratum (NAS) signaling over control plane, connectionless approaches over user plane and keeping UEs in connected mode for small data transmission

71


Dedicated Communication Network

Architecture Enhancements for Services capability exposer (AESE),

Optimizations to support high latency communication (HLCom),

Group Based Enhancements (GROUPE),

Extended DRX Cycle optimization

Monitoring Enhancements (MONTE).

72


Definition of the Dedicated Core Network (DÉCOR) to provide specific characteristics and/or functions or isolate specific UEs or subscribers (e.g., M2M subscribers, or belonging to a separate administrative domain, etc.) and to route and maintain UEs in their respective dedicated core network (for UEs with assigned DCN).

A DCN is comprised of one or more MMEs/SGSNs and (possible) of one or more SGWs/PGWs/PCRFs.

The dedicated MME/SGSN, which serves the UE, selects the dedicated S-GW and P-GW based on UE Usage Type.

Definition of a new optional subscription information parameter ("UE Usage Type") for the HSS subscriber profile, used by the dedicated MME/SDSN to select the S-GW and P-GW: NAS Node Selection Function (NNSF)

73


Architecture Enhancements for Services Capability Exposer (AESE): the Mobile Network Operators (MNO) can offer value added services by exposing these 3GPP service capabilities to external application providers, businesses and partners using web based APIs.

Via one or more standardized APIs, e.g., the OMA-API(s).

Key issue 1: definition of the Service Capability Exposure Function (SCEF) in 3GPP core network.

SCEF provides the means to securely expose the services and capabilities for external parties through homogenous network API) defined by OMA, etc.

The SCEF abstracts the services from the underlying 3GPP network interfaces and protocols.

The SCEF is always within the trust domain of a network operator. An application can belong to the trust domain or may lie outside the trust domain.

74


Key issue 2: setting up an Application Server (AS) session with required QoS, the solution with SCEF interworking with the PCRF is agreed.

Idea: when the SCEF receives the API request from the 3rd party AS to provide QoS for an AS session, the SCEF transfers the request to

provide QoS for an AS session to the PCRF via Rx interface.

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Key issue 3: change the chargeable party, the 3rd party indicates the expected chargeable party to the SCEF, and then the SCEF transfers the request to change the chargeable party to the PCRF via the Rx interface.

Key issue 4: support of derived network resource optimization, by providing relevant information (data traffic, mobility area, location, speed, …) of a communication pattern of an UE or a group of UEs

The SCEF derives appropriate network parameters and provides the derived network parameters to selected appropriate functional entities (e.g., MME, eNodeB, etc.)

Key issue 5: informing the 3rd party about potential network issues

Key issue 6: possibility for background data transfer:

The SCEF receives the API request from the 3rd party, identifies the transfer policy with the corresponding PCRF and forwards the transfer offer to the 3rd party AS

The study result is captured in TR 23.708.

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Support high latency communication (HLCOMM).

Problem

for a. temporarily unreachable devices (for a long period, due to Power Saving Mode, PSM); and b. to support large numbers of such devices

Packet discard when the UE sleeps, frequent retransmissions, load on the CN network, waste of radio resources and UE power when the network unnecessarily conveys retransmit packets, etc.

Solutions:

The DL data can be buffered in the SGW/Gn-SGSN so that when the UE is available again, the data can be immediately delivered.

The AS registers with the SCEF. If an SCS/AS wants to send DL data to a sleeping UE, the SCS/AS registers a new onetime “UE reachability”

monitoring event via the SCEF-

interface/API in order to detect delivery availability.

Coordination between AS and the network on UE latency parameters

in order to delivery data properly by MME

77


Group Based Enhancements (GROUPE),

Issue 1: efficiently delivery the same message (e.g. a trigger request)

to an MTC group of devices located in a particular geographical area.

Solution: using the MBMS architecture is re-used for group message delivery, the BM-SC (Broadc. Multicast Service Centre) allocates a TMGI (Temporary Mobile Group Identity) for a specific MBMS user service.

The SCEF is connected to the BM-SC. SCS/AS provides both the content to be broadcasted and additional information to SCEF.

Issue 2: Devices that belong to a predefined group may overload the MME by generating a large amount of NAS signaling (e.g. may continuously and repeatedly trying to connect to a non-responding server

unnecessary attach procedures). How the MME/SGSN determines (and then distinguish) that UEs belonging to a specific group causing NAS signaling overload/congestion

Solution: using a 3GPP internal group identifier “internal-group-id”

to identify the group to which the UE belongs. It is part of the subscriber data in the HSS and is sent by the HSS to the MME/SGSN as part of normal EPS signalling. The MME/SGSN detects the NAS congestion by measuring some parameters (e.g. attach rate, EPS bearer activation per group, …) and can apply existing NAS level mobility management congestion control schemes

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Proximity Service (ProSe): ProSe direct discovery

It identifies UEs that are in proximity of each other.

ProSe discovery can either be direct or EPC-level and is authorized by the operator.

Examples of potential commercial use cases of ProSe discovery are social discovery, proximate advertising, and consumer alerts of nearby events, gaming that integrate physical-

world elements, education, home automation and supervision of persons not supposed to leave or enter a specific area.

The eNB sets aside resources for discovery on a periodic basis called discovery pool via RRC signaling: set of subframes as well as a period (e.g. 10s).

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Discovery window, where the devices stay on to transmit and receive expressions (e.g., 64 ms), configurable by the operator.

Two modes of resource allocation are supported

In Type 1 resource allocation, UE selects a resource randomly from allocated resource pool every discovery period

For Type 2B resource allocation, eNodeB allocates a logical resource via RRC signaling to the UE (pre-defined hopping pattern)

Devices wake up during a discovery window to transmit and receive expressions, sent as broadcast messages (232 bits) in 2 PRB

ProSe: ProSe direct communication

Direct communication is a broadcast mechanism (no physical layer feedback)

Two physical channels: control and data.

In Mode 1 resources allocation, the eNB explicitly assigns resources to be

used by transmitting devices for control and data transmission for each device via a new downlink control information format (DCI 5) carried via PDCCH or EPDCCH.

Supported only in In-Network scenarios

In Mode 2 resource allocation, an additional data resource pool is defined.

Devices transmit control to announce resources to be used for subsequent data transmission. Receiving devices monitor the control resources to

determine when to wake-up and listen for data transmission.

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ProSe: architecture

ProSe Function: implements the network related actions required for ProSe including

Configuration, authentication and service authorization

Interface PC5

ProSe enabled public safety UE may support the following functions:

One-to-many ProSe Direct Communication over PC5

Procedures to act as a ProSe UE-to-Network Relay.

Exchange of control information between ProSe UEs over PC5

Exchange of ProSe control information between another ProSe-enabled UE and the ProSe Function over PC3

Configuration of parameters (e.g., including IP addresses, ProSe Layer-2 Group IDs, Group security material, radio resource parameters).

81

ProSe: ProSe UE to network relay

82

Public safety

The public safety broadband network will be based a single national architecture based upon the LTE technology

The new "First Responder Network Authority" (FirstNet) is in charge to deploy and operate the high-speed network dedicated to public safety

FirstNet will hold the spectrum license for the network

Allocated band is 700 MHz D Block Band 14 (758-763 MHz and 788-793 MHz)

Non-public safety entities will be allowed to lease the spectrum on a secondary basis

Example services: Direct Mode off-network communications,Mission Critical Voice, Push-to-Talk (PTT) over LTE,Video 1 to many, Messaging, Images, Group text,Non-mission critical voice (e.g., voice over LTE)

Enhancements for public safety in: Proximity Services(ProSe) and Group Call System Enablers for LTE (GCSE_LTE).

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Public Safety Grade

Public safety: Group Call System Enablers for LTE (GCSE_LTE)

Use of eMBMS capabilities in the downlink

The new MB2 interface allows the Group Communication Application Server to communicate and send content to the BM-SC

New QoS Class Identifiers (QCI) 65, 66, 79 and 80 suitable for Mission Critical and non-mission critical PTT services

Other functionalities:

Service continuity when UE is switching between unicast deliver and MBMS delivery

Priority and pre-emption for group communication

84

Local Internet Protocol Access/ Selected Internet Protocol Traffic Offload (LIPA/SIPTO): enhancements in Rel-12

Collocated SIPTO at local network

In Rel-12 enables the offloading of the internet traffic from the RAN node

itself through an embedded P-GW function in the private network

While LIPA was restricted to HNB/(H)eNB, SIPTO extends the offload to some RAN nodes (eNB, (H)eNB, NodeB+ and HNB)

Signaling between embedded GW, RAN node and MME to allow the RAN

node to establish an internal tunnel to flow the data directly between its radio part and the embedded P-GW part

Given that this feature is “co-localized”

andmay not be operated by the adjacent RAN node, the SIPTO bearer must therefore be deactivated as soon as the UE leaves the coverage corresponding to the cells of the served RAN node.

85

LIPA/SIPTO (2): enhancements in Rel-12

SIPTO at local network with Stand-Alone GW

Installing a stand-alone GW composed of S-GW and P-GW

Stand-alone GW can serve more than one RAN node Making up a “Local Home Network (LHN)

The SIPTO bearer and the offloading function can be continued as the UE handovers in the RAN nodes served by the stand-alone GW

For SIPTO mobility, the RAN node must signal at every idle-active transition its pertaining local Home Network ID. If the

MME sees no change of LHN, it maintains the SIPTO bearer; otherwise it triggers the deactivation of the associated PDN connection.

86

Dual Connectivity: enhancements in Rel-13

Dual connectivity for throughput enhancement and for mobility robustness

Unlike CA, where a UE is configured with only one serving cell (i.e., PCell), in DC, separate DRX configurations can be applied to MCG and SCG.

SIPTO to provide DC. Two mechanisms:

SIPTO at Local Network with standalone Local Gateway (LGW)

SIPTO at Local network with collocated Local Gateway (LGW)

87

LTE-Advanced, Release 11

Carrier Aggregation (CA) Enhancements

Home-eNodeB (HeNB) enhancements

Further enhanced Inter-Cell interference Coordination (FeICIC)



Further Self-Optimizing Network (SON) Enhancements

Signaling and Procedure for Interference Avoidance for In-Device Coexistence (IDC)


88



Small cell enhancements: dual connectivity

Home-eNodeB enhancements



Proximity Service (ProSe)

Selected IP Traffic Offloading (SIPTO) enhancements

Public Safety


Carrier Aggregation (CA) Enhancements


Selected IP Traffic Offloading (SIPTO) enhancements

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Network Provided Location Information for IMS (Netloc)

Solutions for making the cell-ID / PLMN ID and local time that the UE is camped-on, available to the IMS nodes when the mobile operator needs to record this information, either to fulfill legal obligations or for charging purposes.

Single Radio Voice Call Continuity (SRVCC)

To improve voice coverage by handing over the voice session from LTE to 2/3G CS domain by priority handover

QoS Control Based on Subscriber Spending Limits (QoS_SSL)

Policy Control Framework has been enhanced with TDF (Traffic Detection Function) for application detection and control features, which comprise the request to detect the specified application traffic, report to the PCRF on the start/stop of application traffic and to apply the specified enforcement actions. The supported enforcement actions are: bandwidth limitation,

gating, redirection. Additionally, usage monitoring report to the PCRF is supported per session and per detected application.

Multimedia Emergency Services (MMES)

Providing services (e.g. simplex, full duplex real time video, synchronized with speech if present, session mode text-based instant messaging, File transfer, Video clip sharing, picture sharing, audio clip sharing) based on trusted applications in support of non-voice communications between citizens and emergency authorities.

Interworking with Wi-Fi Enhancements

Support enhancements to EPC for multi-access PDN connectivity, IP Flow Mobility and seamless WLAN offloading.

Universal Integrated Circuit Card (UICC) Enhancements and UICC Inside Handsets Enabling Femtocell

Enhancement for H(e)NB authentication

Lawful Interception Enhancements

To fulfill the national requirements on lawful interception

Evolved Multimedia Broadcast Multicast Service (eMBMS) Service Continuity and Location Information

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91

What is 5G

5G is associated with the next step of IMT, IMT-2020

Broad consensus that 5G will be introduced around 2020: now discussions are at the first stage

Question: will 5G include another new air interface or a collection of air interfaces, each for a different scenario and use case?

Note: future of 5G wireless access as referred to above is much more than just about radio-interface technology, since 5G wireless access should be the overall future solution to providing wireless access to people and devices.

A clear definition of 5G or 5G requirements is not yet available: requirements such as support of large number of connected devices, “Always online,”

energy efficiency and support of flexible air interfaces

may not be achieved by just an evolution of current systems.

may require 5G to have new protocols and access technologies.

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What is 5G (2)

3G and 4G technologies have mainly focused on the mobile broadband use case, providing enhanced system capacity and offering higher data rates.

Future 5G wireless networks should offer wireless access to anyone, everywhere and anything Internet of Things (IoT)

Users will simply request the information they need, and the information will be delivered to their desired location and device, in an interconnected world

Voice, video, medical, entertainment and other applications and services will be served by a highly integrated and automatically configurable network

In summary, 5G will entail connecting people and things across a

diverse set of scenarios, enabling new services and devices, connecting new industries and empowering new user experiences.

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IoT

A wide variety of cellular-enabled IoT applications will be prevalent by 2020

IoT applications are predicted to grow at a much faster pace than perhaps what existing networks and cellular technologies can optimally handle.

To support possibly billions of IoT devices, a wireless network infrastructure is needed

Highly scalable, higher capacity, but also by optimally differing service needs of various IoT verticals.

Diverse requirements for mobility, latency, network reliability and resiliency: it may require re-architecting key components of the cellular network(e.g. mobility on demand only for some devices and services)

Four pillars: Radio Frequency Identity (RFID), Wireless Sensors and Actuators Network (WSAN), Machine-to-Machine (M2M), Supervisory Control And Data Acquisition (SCADA)

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IoT (2): some use cases

Smart Grid and Critical Infrastructure Monitoring

Smart Cities: smart transportations, smart building, smart home

m-Health and Telemedicine: for improving healthcare access both in remote rural and urban areas

Automotive: Vehicular Internet/Infotainment, Pre-Crash Sensing and Mitigation, Cooperative Vehicles, Inter-Vehicle Information Exchange:

Sports and Fitness

And more …

Extreme Video, Virtual Reality and Gaming Applications

Explosive Increase in Density of Data Usage

Public Safety

Context-Aware Services

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5G requirements: User-Driven Requirements

Battery Life

Per-User Data Rate and Latency: augmented reality, 3D gaming and “tactile Internet”

will require a 100x increase in achievable data rate compared to today and a corresponding 5x to 10x reduction in latency

Robustness and Resiliency: designed for public safety, smart grids and natural gas and water distribution networks

Mobility: support both very-high-mobility scenarios (e.g., high-speed trains, planes), as well as scenarios with low to no mobility for end devices

Seamless User Experience: irrespective from the user location

Context-Aware Network

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5G requirements: Network-Driven Requirements

Scalability

Network Capacity: we can expect a 1000x –

5000x rise in traffic over the next decade

Cost Efficiency

Automated System Management and Configuration

Network flexibility: RAN and core network to evolve and scale independently of each other

Energy Efficiency

Coverage

Security: integrity and confidentiality

Diverse Spectrum Operation: including traditional sub-6 GHz cellular bands for coverage and low-power operation, to above-6 GHz bands including millimeter spectrum for ultra-high data rates (different propagation environment).

Unified System Framework: as flexible and extensible as possible to support WSN (low data rate and delay tolerant) and telemedicine

(high data rate and low latency)97

4G enhancements for 5G

Enhancement of Networking Flexibility:

Local gateways for offloading;

Virtualizations to enable content caching closer to the user

Additional Support for Essential Functions as Fundamental Attributes of Networking Layer: overcoming legacy Internet protocols (and their limitations)

Providing More Flexible Mobility Solutions: reducing the signaling

Expanded Form of Multi-RAT Integration and Management: also to “trusted non-3GPP access”

networks

Enhanced Efficiency for Short-Burst or Small-Data Communication

Expanding Context Information Known to the Network:

The network has no visibility of the application needs

Big-data analytics, advertising and context-relevant offers

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Potential technologies for 5G

Massive MIMO: extend MU-MIMO by having the BS antennas much more than users

RAN Transmission at Centimeter and Millimeter Waves: for short-range scenarios

New Waveforms: more confined spectrum

Advanced Multi-Carrier Transmission

Non-orthogonal Transmission

Shared Spectrum Access: CA, SAS, WiFi integration

Advanced Inter-Node Coordination: ICIC, CoMP, Dual Connectivity

Simultaneous Transmission Reception

Multi-RAT Integration and Management: introduction of logical entities, dense network, HetNets, Relay Nodes

Device-to-Device Communication: Proximity Services

Efficient Small Data Transmission: MTC enhancements

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Potential technologies for 5G (2)

Wireless Backhaul/Access Integration: jointly use of the same frequencies for access and for backhauling (to serve small cells)

the integration is like a multi-

hop communication

Flexible Networks: SDN and NFV

Flexible Mobility: assigning flexible mobility modes to devices by context-aware and SDN (idle mode mobility and active mode mobility)

Context-Aware Networking: adapting the application needs within the network and operator policy

Information Centric Networking (ICN): ICN approaches are focused on the support of future Internet evolution and, in particular, support of new communication models that focus on the distribution of information rather than the communication of data packets between endpoints.

Moving Networks: in high speed scenarios (e.g. 350km/h), the device and cell can be moving like in D2D, V2V or V2I

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Device-to-Device (D2D) communications

Allowing direct communications between two devices (without the BS intervention)

Licensed and non-licensed spectrum

Functionalities:

An overall more efficient mode of transmission (direct peer-to-peer D2D communication)

To extend coverage (device-based relaying).

Cooperative devices where high-speed inter-device communication provides means for “joint”

transmission and/or reception between multiple devices (as a kind of coordinated transmission/reception (“CoMP”) but on the device)

Problem of discovery

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Conclusions

5G is envisioned to have initial deployments around 2020

LTE-Advanced extensions consider enhancements to support the 5G requirements (wherever feasible) before the full 5G is available.

From one side, LTE-A needs to be more efficient for legacy services and improve the network management

From the other side, LTE-A needs to give time to recoup the investment in 4G There are ongoing enhancements in LTE-Advanced that will continue through 2018.

Probably LTE-A is not enough to implement 5G but it is doing its best

It must be recognized that significant breakthroughs in new radio transmission interfaces may be accompanied by a break in backward compatibility.

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References

H. Holma, A. Toskala, “LTE for UMTS: Evolution to LTE-Advanced”, 2nd

Ed., John Wiley & Sons, Ltd., 2011.

4G Americas, “4G Mobile Broadband Evolution: 3GPP Rel-11, Rel-12 and Beyond”, Feb. 2014

4G Americas, “Mobile Broadband Evolution Toward 5G: Rel-12 & Rel-13 and Beyond”, Jun. 2015

4G Americas, “4G Americas Recommendations on 5G Requirements and Solutions”, Oct. 2014

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Mobile broadband system evolution towards 5G: LTE-Advanced Release 10, Release 11, Release 12, Release 13Romeo Giuliano, [email protected] of Innovation & Information EngineeringGuglielmo Marconi University

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mailto:[email protected]

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