Base Stations in the Cloud - VDE ITG€¦ · Base Stations in the Cloud . Content •Objectives, ... (for GPP configurations) ... WCDMA + GSM BBU) User Level

COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.

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Bernd Haberland + Team

28.9.2012 ITG Fachtagung Wien

Base Stations in the Cloud

Content

•Objectives, Use Cases

•Traffic Scenario Example

•Overall VRAN/Mobile Cloud Architecture

•Baseband Pool (MSS-BBU) Functional Architecture

•Virtualization Concept

•MSS-BBU HW Architecture

• Virtualization Concept/Architecture options (for GP P configurations)

•Control Architecture + Resource Pooling management

•Multi-cell System Simulation to verify pooling gain s

•Summary, Next steps

• Reduce processing resources in Baseband Units (BBUs) with loadbalancing (CAPEX)

• Load profiles of different cells (Indoor/Outdoor) are different over time• Processing capacity of BBUs not anymore dimensioned according to Peak Load• Gains can be used:

• to reduce the equipped processing resources• or to create processing headroom for LTE advanced

features

• Reduce number of sites for BBUs (OPEX Reduction)

• „Low cost“ Remote Radio Head (RRH) sites

• Reduce Blocking probability of a cell

Objectives, Use Cases for Mobile Cloud

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• Reduce Blocking probability of a cell

• in case of extreme traffic situation within a cell

• causing peak processing load in distributed solution

• Can be used to support „All-in-One“ Metros with a pool

• BBU Processing Resources allocated from low to high traffic RRH sites• During week-end no traffic at the enterprise area• Processing resources reused for week-end sport events

• Operator Sharing• BBUs of different operators can share the RRH configuration

TCO today with conventional solution

Equipment

Civil work

Support equipmentSite Plan

CAPEX (40%) OPEX (60%)

TransmissionSite Rent

O&M

Power

Objectives, Use Cases for Mobile Cloud (cont.)

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Further Objectives• Easy BBU Processing Capacity upgrade without access to all sites

• Enabling Configuration for LTEadvanced technologies

• NetMiMO (CoMP), HetNet with UL CoMP, Intercell Interference Coordination

• Semistatic Multistandard Mix (LTE/UMTS) in context of standard dedicated BBUs

• M2M Communication Network of Networks included

• Hot zones of sensors, distributed sensor Networks

Dynamic Cell and Traffic Scenarios:2004 Traffic Distribution 8:00-13:00 Milano Scenario

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COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. ALCATEL-LUCENT — INTERNAL PROPRIETARY — USE PURSUANT TO COMPANY INSTRUCTION

Click for animation

MSS-MSS-

RRH

RRH

RRH

RRH

RRH

RRH

RRHRRH

DCC

Multi-standardCloud Base Station

RRHRRH

RRH

RRH

eX2

…

……

• Remote Radio Head (RRH) Cluster: Macro, HetNet, Indoor or any mix

• RRH to MSS-BBU connectivity: 50 -100

Mobile Cloud Overall Architecture

Abis MSS-

BBUBBUDCC

DCC

MSS-

BBU

MSS-

BBU

MSS-

BBUDCC

DCC

DCC

eX2

In the Cloud (inter MSS-BBU)• on User level• on Cell level

MSS-BBU: Multi-site/standard BBUDCC: Decentralized Cloud ControlerRRH: Remote Radio Head

S1Iub

Abis

S1Iub

Abis

S1Iub

Abis

S1Iub

Abis

S1

IubA

bis

eX2: Enhanced X2 interface

Interface MSS-BBU to RRHand MSS-BBU to MSS-BBU:��Low latency, High bandwidth

Base Band Interfacing options – naming

Cell processingUser processing

signal flow (DL)

I II III

IV

FEC

QAM +multi-antennamapping

Resourcemapping

IFFT+CPin

P/S

BBtoRF

encodeto CPRI

III III

IV

FEC-1

QAM-1 +multi-antennaProcessing(e.g. MRC)

Resourcedemapping

CPout+FFT

S/P

RFtoBB

encode

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COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. ALCATEL-LUCENT — INTERNAL PROPRIETARY — USE PURSUANT TO COMPANY INSTRUCTION

• (I): „soft-bit fronthauling“ (softbits + control info)

• (II): „subframe data fronthauling“ (frequency domain I/Q + control info)

• (III): „subframe symbol fronthauling“ (frequency domain I/Q)

• (IV): „CPRI fronthauling“ (time domain I/Q)

• (IV‘): „compressed CPRI fronthauling“ (time domain I/Q)

signal flow (UL)

IV encodeto CPRI

Links from MSS-BBU to Macro site (Downlink)

Transmission bandwidth of Macro site as given below

Process splitting at several potential interfaces

Each Macro site holds 3 sectors:

- LTE, 4 antennas, 20 or 40 MHz

Bandwidth Requirements MSS-BBU to RRH site

[Gb/s] per site "CPRI" IV' III II/100% II/30% I/100% I/30% Data*/100%

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100%

Data rate (40 MHz BW, Gb/s)

29,5 10,9 5,6 5,4 2,5 0,53 0,19 0,24

sites/10 Gb/s link

0 0 1 1 4 18 53 41

Data rate (20 MHz BW, Gb/s)

14,7 5,5 2,8 2,7 1,25 0,27 0,09 0,12

sites/10Gb/s link

0 1 3 3 8 37 111 83

• Link level protocol not yet included on I,II and III.*average Spectral efficiency:2,0 b/s/hzOverhead included

MSS-BBU Functional Architecture

RRHm

RRH1

RRH2

RRH3

RRH4

RRH5

MUX/DEMUX

MUX/DEMUX

MUX/DEMUX

S1 -MME

Spreader/Despr

Spreader/Despr

Spreader/DesprSpreader/Despr

RB 1UP 1

UP 2

eNBControlFunctions

Spreader/Despread

NBControlFunctions

Schedulerantenna

cell

PHYcell

Iub

S1 - U

RB 1UP 2

RB 1UP 3

RB 1UP 4

RB 1UP 5

MUX/*DEMUX

antenna

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RRHm

To other MSS-BBUs

Cell Signals

UP: User Processing stack eX2: Enhanced X2 *: Framer/Deframer/IFFT/FFT are assumed to be in the RRH

MAC-(e)hs/eScheduler


UP j-1

UP j

Functions

BTSControlFunctions

DCCLTE UMTS


PHYcell

eX2Abis

UP i-1

UP i

cell

Interface II

MSS-BBU Functional Architecture (2)Some definitions

UP: Dedicated User Processing (DL/UL) for LTE and U MTS to be virtualized

For LTE:

S1-MME Termination stack: ETH/IP/SCTP/S1AP ded.

S1-U Termination stack: ETH/IP/UDP/GTP-U

Uu Control Plane stack: RRC/PDCP/RLC/MAC/PHYuser

Uu User Plane stack: PDCP/RLC/MAC/PHYuser

For UMTS:For UMTS:

Iub Termination User Plane stack for HSPA:

ETH/IP/UDP/FP(HS-DSCH/e-DCH)

Uu Termination stack for HSPA: MAC (e)hs/e/PHYuser

A set of UPs of one standard can be allocated to one CEM up to its maximum bandwidth

UPi: overal number of LTE users in a Cloud Base Station

UPj: overal number of UMTS users in a Cloud Base Station

i,j: not fixed depends on bandwidth for the singular user

MSS-BBU Functional Architecture (3)

PHYcell (LTE): MUX/DEMUX function with statistica l MUX gains

---� IFFT/FFT/ CPI/CPR can be shifted to RRH (save bandwidth)

PHYcell /UMTS): Spreader/Despreader

Any UP of one standard can be allocated to any PHYcell of the same standardAny UP of one standard can be allocated to any PHYcell of the same standard

Scheduler for LTE and MAC (e)hs/e Scheduler for UM TS/HSPA

RRHm: overal number of sites/RRHs connected

Virtualization Principle of a UP (example LTE)

UP1…UPx

BBU2

UPx+1… UPn

Cell Control Functions

DCCS1-MME S1-U

MSS-BBU internal connection

Inter MSS-BBU via eX2 IF

DCC

MME/SGW

Router

Scheduler

BBU1

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Some definitions:- For the users 1..x the BBU1 is the Home and the Serving BBU- For the users x+1..n the BBU1 is the Home BBU and the BBU2 the Remote BBU - For the users n+1…n+y the BBU1 is the Home BBU and the BBU3 the Remote BBU

PHY cell BBU3UPn+1… UPn+yInter MSS-BBU

via eX2 IF

DCCScheduler

MSS-BBU1

MSS-BBU2

XFPXFPXFPXFP

Poosible MSS-BBU HW Architecture (for Light Radio)

BBU2 BBU3

RadioSite k-1,k

BBUk

Radio Sitek+1

RadioSite 5,6

RadioSite 3,4

MUXarray BBU1

Cell/User Signal (from other MSS-

XFPXFP XFPXFP XFP

Radio Sitek+2

Radio Site m

XFP

RadioSite 1,2

XFP

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Abis Iub S1-U

Router/Address Dispatcher

DCC

S1-MME

eX2 IF

eX2to other

MSS-BBUs

LTE+GSM

WCDMA + GSM

MSS-BBU)

User Level

Ethernet Switch

Highspeed Interconn.

Basic Control Architecture and S1/X2 flows

DCC DCCeX2eX2

ControlControlDCC

RouterS1 RouterS1

S1 data

S1 datato/from X2

S1 data to/from X2

S1 data

RouterS1

S1 data to/from X2

S1 data

M SoC

C+M SoC LRMM SoC

C+M SoC LRMCEM

C+M SoC LRMBBU

BBU LRM

MSS-BBU1

M SoC

C+M SoC LRMM SoC

C+M SoC LRMCEM

C+M SoC LRMBBU

BBU LRM

MSS-BBU2

eX2eX2

Data Data M SoC

C+M SoC LRMM SoC

C+M SoC LRMCEM

C+M SoC LRMBBU

BBU LRM

MSS-BBUn

S1 datafrom/to X2

S1 datafrom/to X2

S1 datafrom/to X2

LRM: Local Resource Manager

Control Flow Architecture

RBC: Radio Bearer Control

Multi-cell System SimulationQuantification of Possible Processing Resource Savings

100 %

? %

Controller

Mapping of processing effort

KPIs

Mapping of transport format

to processing effort

Controller

Non full buffer

traffic generator

Modem

SchedulerControllerto transport

format

MSS-BBU Processing Resources

Scenario and Basic Simulation Parameters

Parameter Value

Scenario LTE, 10 MHz uplink, 10 MHz downlink FDD

Playground 4.1 km2, 19 sites, 500 m distance, 3 sectors per site

Mobiles Unlimited number, not moving

Request messages Created on application layer according to a Poisson inter-arrival process; constant message size of 1 kB

Load distribution Randomly according to a mix of Uniform & Gaussian, mean in central site

Response messages One per request; varying object sizes according to a mix of 3 log-normals [Hernandez-Campos]

Channel model Pathloss and static shadowing

Handover Based on SINR

Outage Requests from mobiles dropped if SINR below -6 dB

Scheduling Frequency-diverse allocation cell reuse one scheme, Resource-fair round-robin bandwidth assignment

Link adaptation Capacity calculated according to Shannon formula, no losses, no HARQ/ARQ

Processing resource model

Processing resources scale linearly with the share of allocated radio resources

[Hernandez-Campos] F. Hernandez-Campos et al., Variable heavy tails in Internet traffic, Performance Evaluation, Vol. 58.2–3, page 261-284, Nov. 2004

Geographic User Load Distributions

• After request generation, the position of the associated user is chosen according to a mix of Uniform and Gaussian parameters

• Single hotspot in the center to model non-uniform load distribution

• Varying share of hotspot users varies the corresponding spatially non-uniform load distributions and their spatial variance (hotspot size (standard deviation) not varied)

100 % uniform 80 % uniform 50 % uniform

deviation) not varied)

• 100% hotspot users: less than 20% resource utilization for 90% of the time and less than 38% for 99.9% of the time

• 100% uniformly placed users: less

Pooling Gains Resulting from User Load Distribution and Traffic Model

• Quantiles for 90%, 95%, 99% and 99.9% of the system time at its capacity limit.

60%

70%

80%

90%

100%

use

d r

eso

urc

es

99,9%tile

99%tile

95%tile

90%tile

than 65% resource utilization for 90% of the time and less than 91% resource utilization for 99.9% of the time

� Expected improvement up to a factor of 3 of the resource utilizations by the cloud approach between the uniform to non-uniform user distribution cases

0%

10%

20%

30%

40%

50%

60%

0 0,2 0,4 0,6 0,8 1fraction of uniformly placed users

use

d r

eso

urc

es

(contributed from Dipl.-Ing. Thomas Werthmann from the Institute of Communication Networks and Computer Engineering in Stuttgart, Germany)

Resource Usage Trace for 100 % Uniformly Placed Users – Sum Over All Cells


Resource Usage Trace for 50 % Uniformly Placed Users – Sum Over All Cells


Summary, Conclusion

•Objectives and Use Cases of Mobile Cloud are discussed and illustrated

with a Traffic Scenario Example

•A VRAN/Mobile Cloud Architecture is discussed

• High bandwidth, low latency backhaul needed

•Discussion of a Baseband Pool (MSS-BBU) Functional Architecture

• A possible Virtualization Concept is presented with an

approach for a MSS-BBU HW Architecture

•Readout of a Control Architecture + Resource Pooling management

• First Multi-cell System Simulation to verify pooling gains are shown

• significant pooling gains can be shown (20-80%) depending on spatial

distribution of users (uniform/non-uniform)

Documents

Base Stations in the Cloud - VDE ITG€¦ · Base Stations in the Cloud . Content •Objectives, ... (for GPP configurations) ... WCDMA + GSM BBU) User Level