Evolution of cellular wireless systems from 2G to 5G

6-13th October 2017

Enrico BuracchiniTIM INNOVATION DEPT.

Outline- Part I• Wireless mobile systems main concepts

• GSM & GPRS Overview

• UMTS R99 main characteristics

• HSDPA: - Rationale, main characteristics and differences vs R99- R5 UE categories- HSPA evolution hints

…A wireless mobile system

PSTN / ISDNOther Networks

IN

MSC (Switching & MM)

Control ofRadio Stations (BSC/RNC)

RadioCoverage

(BTS,Node B)

RadioAccess

Web, Internet

ACCESS TECHNIQUES FORMOBILE COMMUNICATIONS

P - PowerT - TimeF - Frequency

P

T

P

T

F

P

T

F

FDMA (TACS)

TDMA (GSM)

CDMA (UMTS)

F

Cellular System - Frequency Reuse

Theoretical Cluster

12

34

56

7 12

3

4

56

7

12

34

56

7

1 2 3 4 5 6 7

bandwidth

Cluster & channel grouping

A B C D A B D

1 2 3 4 5 6 N

A = { 1, 5, 9, ....}

Frequency reuse concept

B

A

B

A

B

B

A

B

A

BA

A

B

A

B

D

C

D

C

D

C

D

C

D

C

D

C

D

C

D

Choosing The Cluster Size

CS

CAPA CI T Y

Q U A L I T Y

Choosing The Cell Size

CS = CONSTANT

R

CAPA CI T Y

COS T

Cell Size

a) b)

C C

B B

B

B

C

C

C

C C

C

C C

A A A

A A A

A A

B B

B B

B B B

A A

A

Antenna solutions for cellular coverage

a) b)

Planning the cell size and layouta matter of channel/Km2 requirements (traffic constraint)

tuning the cell sizeover a single layer

adopting overlapping coverage solutions (umbrella cells)

GSM/GPRS

GSM FREQUENCIES

900 11001000 1200 1300 1400 1500 1600 1700 1800 1900

GSM 900 GSM 1800

MHz

890 935915 960

Up Down

1710 1785 1805 1880

Up Down

124channels

374channels

BURSTTRANSMITTED

BYTDMA FRAME

(4.6 ms)

MOBILE 1

MOBILE 2

MOBILE 8TIME

TIME-SLOT: 577 s SIGNAL BURST: 543 s

GSM functions - TDMA access technique

GSM traffic burst structure

T3

S1

S1

13

GP8.25

Coded Data57

Training Seq. 26

Coded Data57

TypeNumber of Bits

148 Bit

Stealing flagGuard Time

Tail bits (guard bits)

The GSM system Architecture & Equipment

MSC Mobile Switching CenterOMC Operations & Maxz intenance CenterSM-SC Short Message Service Center

MS Mobile StationBTS Base Transceiver StationBSC Base Station ControllerBSS Base Station Subsystem

MS BSS

VLR

BTS

PSTN

ISDN

Other Netws

MSCBSC

HLR EIR

OMC

AuC

SM-SC

HLR Home Location RegisterVLR \ CenterEIR Equipment Identity Register

• PHASE 1– Basic Services

» Telephony

» Emergency calls

» Short Message Services (Mobile Terminated & Originated)

» Group 3 Fax & CS data @ 9.6 kb/s

» Call Forwarding & Barring

• PHASE 2– New Supplementary Services

» Call Waiting & Call Hold

» Line Identification & Multi-Party Call

» Closed User Group & Advice of Charge

GSM Standard Evolution (I)

• PHASE 2+– CS & PS Data Services

» HSCSD (High Speed Circuit Switched Data)

» GPRS (General Packed Radio Service)

» EDGE (Enhanced Data rate for the GSM Evolution)

– Supplementary Services» CCBS (Completion of Call to Busy Subscriber)

» USSD (Unstructured Supplementary Service Data)

– Other» Specific services support (e.g. SIM Toolkit)

» Mobile Number Portability

GSM Standard Evolution (II)

General Packet Radio Service (GPRS)

External Data

Network

BSC

BTS

GGSN

MSC

SGSN

VLRHLR

Signalling

Data

RRM

• Two (on 4) implemented coding scheme: CS1 & CS2, for a bit rate of 8 kb/s & 12kb/s per slot

• For a 4 (DL) +1 (UL) terminal, maximum bit rate @ 48kb/s (DL): the effective one is around 40kb/s

Class A:PS&CS simultaneouslyClass B: registration to both PS & CS, but no simultaneous usageClass C: registration & usage alternate

GatewayMobility managementRouteingEncapsulation

Mobility managementAuthenticationCipheringRouteing

• New modulation scheme to increase the data rate per slot: 8 PSK

• Both CS (ECSD) & PS (EGPRS)• ECSD: up to 32 kb/s x slot & peak rate of 64kb/s• EGPRS: up to 59.2 kb/s per slot & peak rate of 384 kb/s• New terminals (dual-mode EDGE/GSM) & new transceiver in

BTSs

Enhanced Data rate for the GSM Evolution (EDGE)

UMTSR99

IMT-2000 IMT-2000

1885 20251920 2010

MSS

1980 2110 2200

MSS

2170 MHz

ITU

IMT-2000 IMT-2000

1880 20251900 2010

MSS

1980 2110 2200

MSS

2170 MHz

EUROPE

DECT

UMTS core bands assignment

UMTS R99 architecture

RNC

RNCNode B

Node B

Node B

Node BUTRAN

Iucs

Iur

Iub

Access Network Core Network

HLR

BTS

PSTNISDN

Packet Data

Networks3G SGSN GGSN

3G MSC/VLR

Iucs Iups

Iups

Gs

Gn

FDD (WB-CDMA) technique

P - PowerT - TimeF - Frequency

P

T

F

CDMA (UMTS)

All the users are on the same frequencies and they are distinguished by means of a code

Spread spectrum techniques

AWGN CAPACITY WITH LIMITED SPECTRUM

C=B log2 (1 + S/N)[C]=bit/s [B]=Hz S/N=signal to noise ratio

A given bit rate R canbe obtained through

Narrow band and high S/N

Wide band and low S/N

General characteristics of spread spectrum systems

• Robustness against jammers and fading• Low interception probability• Multiple access capability• Frequency reuse 1

DS-CDMA

• Users sharing the same band are transmitted simultaneously on the same carrier

• Users are distinguished each other by means of a “code” and, the mutual interference is reduced during the “decoding” process

• In the DS-CDMA technique, the spreading is obtained multiplying the user signal by the signal associated to a “code” (a PN sequence or an orthogonal sequence)

BPSKMOD.

BPSKDEMOD.

b(t)

c(t)

x(t)

j(t)

z(t)

c(t)~~

fo

z(t)= b(t)c(t) + j(t)

z(t)c(t)= b(t)c2(t) + j(t)c(t) = b(t) + j(t)c(t)

spread interferer

Direct Sequence-CDMA

f

f

f

f

f

S(f)

Spreading and de-spreadingwideband interference

Original signal, band Bn

Spread signal, band Bw

Expanded signal plus broadband interference in the receiver input

Signals after de-spreading

Signals after the reception filter

The rake receiver

X

i

i

je i

X

n

n

je n

propagation channelcodes

generator

correlator

channelestimat.

correlator

channelestimat.

receiver

i

n

phase recovery

phaserecovery

TDD (TD-CDMA) technique

One Time Slot

1 2 3 . . . 14 15

Codes

Energy

Time

frame with15 time slots

WB-TDMA/CDMA

UTRA/FDD UTRA/TDD

Access technique WCDMA Hybrid WCDMA+TDMAChip rate

Carrier spacing 4.4-5 MHz

3.84 Mcps (SF FDD:4-256, TDD 1-16)

Frame duration 10 ms N. slot per frame 15

BTS synchronization Not required Not required (advisable)

Modulation DL: QPSKUL: Dual-channel QPSK UL: QPSK

Coherent receiver Uplink e downlink

Multi-rate Variabile SF + Multi-code + Multi-slot (TDD)

Main parameters

DL: QPSK

Soft Handover and Macrodiversity (WCDMA)

UE

Softer HODedicated Data Channel, Dedicated Packet Channel

RNCMS receives from both Sectorsthe same information at the same time

LC=XSector 1

Sector 2BTS

LC=Y

LC = Long Code

Soft HODedicated Data Channel

RNC

MS receives from both BTS the same informationat the same time

BTS 1

BTS 2

LC=X

LC=Y

LC = Long Code

Macrodiversity

circuit 1

circuit 2

Frame selection

Node B 1

Node B 2

RNC UMSC

Soft Handover and macrodiversity

CELL A CELL B

CELL C

Signal margin

Soft Handover region

“ADD” threshold

“DROP” threshold

Time margin

CPIC

H Received power

TIME

“Soft capacity & cell dynamic”

C/I 1/N

Cell with radius “R” and “N” users

We assume that the user density increase:Cell with radius “R” and (N+X) N users

(C/I)’ 1/(N+X) C/I

In the new load situation if we want to stick tothe original C/I target we have to reduce the cellradius

N

N

N+X

Capacity: single cell, perfect PC Eb

Io

CTI/W

C/RI/W

==C = user signal powerR = bit rateW = spreading bandwidth

In case of perfectpower control

I=C(N-1)

1

(N-1)=

Eb

Io

C/R

C(N-1)/W= .W

R

1Eb/Io

= .WR

(N-1)

Exploitation of source activity and sectorization

d: source activity factor (for voice, the ideal value is 0.38, actually, a typical assumption is 0.5)

Gsect: sectorization gain (2.2-2.4 for three sectored antenna)

1Eb/Io

.WR

N 1d

. . Gsect Site capacity

Capacity: multiple cell

Intercell interference is taken into account introducing a factorusually indicated with “f” or “i” and defined as:

f = (other cell interference)/(intracell interference)

1Eb/Io

.WR

N 1d

. . Gsect . 1/(1+f)

f, changes according to the scenario (typical values 0.4-0.6);“f”, is sometimes known as “reuse factor”of the CDMA system

Cell dynamic

S = signal power

q SN W

0

i = intercell interference to intracell interference ratio

j = external interference referred to the thermal noise power

m = number of coninuously active users

jWNimS

RWq

NIE bb

++1+10

00

The “pole” of q is reached when m = mmax

)-1(+1

00

bb ENI

RW

jq

maxmm

bb ENI

RW

im 00

max+

)+1(1

00

00

+)+1(

)1(+

NIEimR

W

jNI

E

qb

b

b

Example of signal to noise ratio (“q”) versus the load

-15

-10

-5

5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1h

q [d

B]

j = 0bR

W = 12800 + NI

Eb = 7 dB

46

W-CDMA – Radio Resource Management

RRM – role Quality of Service controlCall Admission Control and Traffic measurementHandoverPower controlPacket scheduling

RNC

power and loadcontrol

power control

power controlhandover controladmission and load controlpacket scheduling

47

Admission Control(up-link algorithm)

The Admission Control works through a soft limit, introduced to keep the inteference within a given threshold

THTOT III

Interferencelevel

Load

maximumNoise Rise(evaluated)

ITH

ITOT I

L

Threshold from the cell planning

Evaluation of the interference step

i

ibiiUL f

WNE

Rη )1(/ 0

risenoiserisenoise

UL 1

Power-based

Throughput-based

48

Congestion Control(functional scheme)

load

time

congestionthreshold

histeresis

congestionresolved

congestioncontrolaction

reporting period

Events modifying the operative status:• resources are re-negotiated by the active calls• the modification of the interference conditions• the modification of the propagation conditions and power configuration

The control is acting on:• the interference on the up link• the power generated on the down link

Specific actions on:• call admission• cell ray• BLER• radio bearer configuration• inter frequency handover

49

Packet schedulingflows

scheduler

chan

nel

Scheduling options• Fair throughput (strict RR)

• Fair resource (time, power, codes)(unfair throughput, depending on the channel status)

• C/I based: priority to the users experimenting the best channel quality

• Max C/I: within the Transmission Time Interval, just users experimenting the max values of C/I (high delay for badly served users)

• Proportional fair resource: uses the control quality estimation and the remaining work

50

Radio Interface - protocol architecture (3gpp 25.301)

RLCRLCRLC

RRC

MAC

Physical Layer

L3

L2/MAC

L1

C-plane U-plane

Logicalchannels

Transportchannels

RLC

51

MAC Services and Functions

mapping

phy ch phy ch

DCH DCH DCH

Coding and

multiplexing

mapping

phy ch

DCH DCH

Coding and

multiplexing

• set-up, release of logical channels• data transfer service on logical channels• allocation/re-allocation of radio resources• measurement report

• Selection of the transport format

• Handling of priority within one user/between users

• Scheduling of control messages (broadcast, paging,

notification)

• Multiplexing/de-multiplexing of higher layers PDUs

on/from common or dedicated transport channels

• Contention control on the random access channel

Functions

52

Retransmission Protocol - services and functions

• Layer 2 connection set-up and release• transparent data transfer• unacknowledged data transfer• acknowledged data transfer

• connection control• segmentation and re-assembly• error detection/recovery and in-sequence delivery• transfer of user data• flow control• duplicate detection• QoS adaptation

Functions

Services of RLC

RCLP PDU RCLP PDU RCLP PDU

160 bit 160 bit 160 bit

10ms 10ms

32kbit/s 16kbit/s

53

Radio Resource control - services and functions

• Broadcast of information provided by the Core Networkrelated to the access segment

• Set-up, maintenance and release of an RRC connection

• Set-up, maintenance and release of radio bearers on the user plane

• Assignment, reconfiguration and release of radio resources for the connection

• Arbitration of radio resource allocation between cells

• RRC connection mobility functions

• Quality of Service control and radio resource allocation among the cells

• Admission and congestion control

• Control of the MS measurement reporting

54

Quality of Service(mapping of the traffic casses on the RABs)

CS Domain PS Domain

conversational streaming interactive background

TMRLC

UMRLC

TMRLC

UMRLC

AMRLC

AMRLC

AMRLC

DCH DCH DCH DCH DCH DCHRACH/FACH

Real Time traffic Non Real Time traffic

55

TE MT UTRAN CN EDGENODE

CNGateway

TE

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service

CN BearerService

BackboneBearer Service

Iu BearerService

Radio BearerService

UTRAFDD/TDD

ServicePhysical

Bearer Service

Each RAB is assigned: the traffic class (e.g. interactive), the max bit rate, the delay, the error rate, the residual error rate, the comm. Domain (CS, PS), the supported application (e.g. voice)

The RAB is mapped on a Radio Bearer by setting-up the suited parameters for the Physical and Layer 2 protocols

Radio Access Bearers (RAB) - 3GPP 23.107

56

Peak bit rate[kbit/s]

Delay sensitivity TransportChannel Domain

4,75 12,2 110-3 DCHCircuit

64; 128; 384 110-6 DCHCircuit

Streaming 57,6 110-4 DCH Circuit

Streaming 64 110-4 DCH Packet

Interattive or Background

64 384 110-4 DCH

Interattive or Background

1200 14400 110-4 HS-DSCH *

* High Speed DL Shared Channel, used with the HSDPA (High Speed Downlink Packet Access) feature, introduced with Release 5 UMTS

RAB as function of the service class - 3GPP TS 34.108

Service class

Conversational (e.g.with adaptive encoding)

Conversationall(e.g. video call)

Packet

Packet

Sensitive to delayand Jitter

Sensitive to delayand Jitter

Sensitive to Jitter

Sensitive to Jitter

Moderate sensitivity to delay

Moderate sensitivity to delay

ResidualBER

UMTS- HSDPA (R5)

HSDPA positioning vs other solutions

100 m 1000 m 10 km

100 kbit/s

1 Mbit/s

10 Mbit/s

UMTS Release 99

HSDPA (UMTS Release 5)

WLAN (802.11b)

EDGE

GPRSVelocità di

TrasmissioneRaggio di Cella

bit rate

cell radius

HSDPA rationale• to improve data speeds per user

– High speed download (mails, video and mp3)– Video streaming – Highly interactive games– High speed browsing

• to improve service latency• to improve Network Capacity

• The HSPA deployment is based on the reuse of 3G network infrastructure:

– same NodeB (modified) and RNC– same Core Network– same site/mast/antennas.

3GPP HSDPA – Rel.5– Introduced in 3GPP – Release 5– Main Characteristics vs R99:

» Shared packet transmission» Higher order modulation

(16QAM)» Shorter TTI (2ms vs 10ms)» Adaptive modulation &

coding» Fast Link Adaptation» Fast Hybrid HARQ» Advanced packet scheduling

HSDPA – the innovative capabilities

Single transmission channel shared among several users on the down link Scheduling of the transmission queues performed by the base station; MAC

layer partially decentralised Multiplexing over the time domain (TTI - 2 ms) Hybrid techniques (H-ARQ, Hybrid ARQ) for corrupted radio blocks,

managed by the B-node Adaptive modulation and coding, based on a channel quality indicator (CQI)

transmitted by the mobile Use of 16-QAM modulation to increase the spectral efficiency whenever

under good channel conditions Bit rate up to14 Mbit/s.

HSDPA: Main characteristics vs UMTS R99

63

Fast Scheduling and CQI – the CQI principle

Nodo B

Mobile 1

Mobile 2

Decision on sheduling and AMC*

The CQI (Channel Quality Indicator) is derived by the MS every 2 ms on the basis of the pilot channel (CPICH). It specifies: power, modulation and coding scheme the MS is ready to receive for the subsequent TTI, to maintain a Block Error Rate (BLER) lower than 10%

* Adaptive Modulation & Coding

R5 UE categories

UE categories defined on the basis of:1) Number of codes that can be elaborated per each TTI2) Maximum bit rate over the entire frame3) Minimum interval elapsing between two subsequent TTIs4) Possible modulation schemes (only QPSK, or both QPSK and 16-QAM)5) Storage dimension for the HARQ, e.g the less powerful class does not

accept the Incremental Redundancy at the maximum bit rate.

3GPP TS 25.306

1,6

0,8

13,4

9,6

6,7

6,7

3,4

3,4

1,6

1,6

1,1

1,1

Bit rate di picco al livello RLC [Mbit/s]

1,8

0,9

14

10

7,2

7,2

3,6

3,6

1,8

1,8

1,2

1,2

Bit rate di picco al livello fisico [Mbit/s]

QPSKNo1512

QPSKNo2511

QPSK, 16-QAMNo11510

QPSK, 16-QAMNo1159

QPSK, 16-QAMSi1108

QPSK, 16-QAMNo1107

QPSK, 16-QAMSi156

QPSK, 16-QAMNo155

QPSK, 16-QAMSi254

QPSK, 16-QAMNo253

QPSK, 16-QAMSi352

QPSK, 16-QAMNo351

Modulazioni supportate

IR al maxbit rate

Minimo intervallo inter-TTI

Max. Num. CodiciClasse

1,6

0,8

13,4

9,6

6,7

6,7

3,4

3,4

1,6

1,6

1,1

1,1

Bit rate di picco al livello RLC [Mbit/s]

1,8

0,9

14

10

7,2

7,2

3,6

3,6

1,8

1,8

1,2

1,2

Bit rate di picco al livello fisico [Mbit/s]

QPSKNo1512

QPSKNo2511

QPSK, 16-QAMNo11510

QPSK, 16-QAMNo1159

QPSK, 16-QAMSi1108

QPSK, 16-QAMNo1107

QPSK, 16-QAMSi156

QPSK, 16-QAMNo155

QPSK, 16-QAMSi254

QPSK, 16-QAMNo253

QPSK, 16-QAMSi352

QPSK, 16-QAMNo351

Modulazioni supportate

IR al maxbit rate

Minimo intervallo inter-TTI

Max. Num. CodiciClasse

R5 UE categories and related bit ratesclass max

codes #minimum TTI

interval

peak bit rate at layer 1

(mbps)

peak bit rate at RLC level

(mbps)

IR at peak

bit rate

supported modulation

Yes

Yes

Yes

Yes

3GPP TS 25.306

66

HSPA Evolution hints

“HSPA Evolution” 710 Ericsson White Paper: www.3g4g.co.uk/Hspa/HSPAE_WP_0710_Ericsson.pdf

“HSPA+ for EnhancedBroadband”

Qualcomm WP, 2009

Outline- Part IICOMING UP SOON……NEXT WEEK!!!

• LTE

• LTE Advanced

• 5G overview

…..STAY TUNED

Thanks for your kind attention