© 2009 IBM Corporation The Future of Software Radio: Wireless Network Cloud Parul Gupta, Smruti...

© 2009 IBM Corporation

The Future of Software Radio: Wireless Network Cloud

Parul Gupta, Smruti Sarangi, Shivkumar Kalyanaraman [IBM Research – India]

Zhen Bo Zhu, Lin Chen, Yong Hua Lin, Ling Shao [IBM Research – China]

© 2009 IBM Corporation2 Version 0.1

Outline

Cellular wireless systems and convergence trends (esp in emerging markets)

Today’s 2G/3G architectures and the trend towards 4G (all-IP and OFDMA for PHY/MAC layers)

Increasing computational costs, low utilization with future generations of technology, upgrade cycles, growing maintenance / OPEX costs.

SDR evolution: – Firmware OTA upgrades on vendor platforms, – From DSP/FPGA platforms to Hybrid IT platforms, – Multi-technology / multi-operator support– Virtualization & cloud given fiber-to-tower availability


Wireless: short technical summary

1. Scarce bandwidth (10-100 MHz/operator)

2. Spectral Efficiency: MHz -> Mbps (signal to noise ratio is key!)

Rate

Mobility

2G

3G

4G802.11b WLAN

2G Cellular

Other Tradeoffs: Rate vs. Coverage Rate vs. Delay Rate vs. Cost Rate vs. Energy

3. Tradeoffs: Rate vs X(no free lunch!)

Today With femto cells & MIMO antennas

Wireless IT convergence

Wireless networks are designed to maximize spectral efficiency, support mobility, coverage, and Quality-of-Service under severe spectrum/bandwidth constraints

Wireless networks are designed to maximize spectral efficiency, support mobility, coverage, and Quality-of-Service under severe spectrum/bandwidth constraints

In emerging markets the dependence on wireless is high and growing. ARPU pressures are severe: $2 incremental ARPU today. Operators aggressively outsource their (wireless/wired) networks and IT.


Wireless Convergence: Closed Vertically Integrated to Horizontal Open

TDMA/CDMA

Circuit Voice;

Data overlay

2G/3G wireless

Integrated MAC,

network functions

Radio layer: OFDMA/MIMO

Network layer: IP

Middleware: IMS, SDP

Apps: Unified Comms (multimedia),

Smarter Planet, mobile VAS, Internet apps, Spoken Web/SMS platforms…

4G wireless

System: IT and wireless systems are approaching similar system architectures

Network Services: Convergence of enterprise wireless and operator wireless services

Application/Solutions: Seamless integration and interaction of wireless infrastructure and mobile applications

Convergence at

Systems Level

Convergence at

Network Services Level

Convergence at

Application/Solutions Level

There is another interesting twist in this wireless / IT convergence at the systems level


BS

BS

BS

BS

Radio network controller

Radio network controller

Mobile switch center

Service support node Gateway

PSTNPSTN

Access Network Core Network

2G-3G wireless network architecture

Service Network

SMS/MMS

WAP GW

4G Wireless Network over Wireless Network Cloud

InternetInternet

SMS/MMS

IMS

Content Service

Web Service

GS

M

GS

MW

iMA

XT

D-S

CD

MA

BS cluster

LTE

WiM

AX

WiM

AX

LTE

BS cluster

Cloud of Wireless Access Network + Core Network

Edge gatewayManagementServer

BillingEdgegateway


Service support node

PSTNPSTN

Service Network

2G/3G/4G Wireless over Wireless Network Cloud

InternetInternet

SMS/MMS

IMS

Content Service

Web Service

GS

M

GS

MW

iMA

XT

D-S

CD

MA

BS cluster

LTE

WiM

AX

WiM

AX

LTE

BS cluster

Edge gatewayManagementServer

BillingEdgegateway

Service on Edge

Cloud of Wireless Access Network + Core Network


Mobile Infrastructure Network Hierarchy

Core Network Radio Access Network

Challenges: The radio access network is a costly and continuous investment ($100B+). With reducing ARPUs and need for broader nationwide coverage, there are more initiatives for sharing infrastructure


Various Forms of Infrastructure Sharing in Wireless Networks

Network Sharing (eg: rural) Base Station Sharing (leads to cloud)

Antenna Sharing Tower Sharing (very popular)

BSC BTS

Owner #1 Retail

Owner #2 Retail

MSC

BSC BTS

Owner #1 Network

Owner #2 Network

BSC BTS

O

BSC BTS

Owner #1 Network

Owner #2 Network

BSC BTS

Base Band UnitBSC

Owner #1 Network

Owner #2 Network

BSCSDR

BTS

RRU


Towers: Passive vs Active Infrastructure Sharing

© 2009 IBM Corporation10

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Passive Sharing and Tower Companies

Eg: Indus Towers (JV controls towers of Bharti, Vodafone, Idea) has 100K towers. Tata Teleservices, Aircel have signed deals with BSNL for sharing 60K+ towers.


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Towards Active Sharing: Unbundling Base Stations: RRU + BBU

Distributed base station

– RRU (Remote Radio Unit)

– BBU (Base Band Unit)

Two key standards enable distributed base station development

– CPRI

– OBSAI

Benefits of distributed base station

– Reduce cost of facilitate infrastructure

– Reduce power consumption

– Easy of installation

– Flexible deployment model

Traditional Integrated Macro BS

Distributed BS: RRU + BBU

RRU

BBU


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Distributed base station deployment #1: under the tower

70% - 80% power consumption is RRUs

3 RRU: 100 – 150W/RRU

1 BBU: 100W

Requirement & Challenges to BBU

light weight < 10Kg

small size (1U – 2U)

low power consumption (< 100W)

Scenario #1: Unbundle at the tower

BSC

BBU

MSC

BBU

RRU RRU

<100m

RRU-BBU Distance <100m5-10Km

5-10Km


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Software Radio & Software Defined Radio: One way of BBU impln


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Multi-Technology Software Radio: 1 BBU Bladecenter vs 5 boxes


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Multi-Operator Base Station with Software Radio


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Active Infrastructure Sharing: Field Trial in India (IBM/partner)


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IO & GPS module

CPRI/OBSAI/

Ir

SWR Base Station

RRU

GE/E1/T1/STM-1

To RNC/ASN-GW/AGW

RRU adaptor

...

PC

Ie/IB

sw

itch

GE

sw

itch E1/T1/STM-1

GPS module

Base band processing

accelerators

RRU adaptor

Base band processing server(PHY, MAC, C&M)

...

Base band processing server(PHY, MAC, C&M)

General purpose servers

Unbundled SDR BS w/ Open Wireless Interfaces & IT Platforms


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Distributed base station #2: distributed RRU + centralized BBU pool

Benefits

– Fit for super urban, urban with high density of traffic

– Highly scalable– Improve utilization by resource sharing– Reduce management cost

Requirements & Challenges to BBU

– High density– Resource sharing with BBU pool– Low power consumption

Key barriers:

– Fiber distance (<10Km)– Increasing IO data throughput >10Gbs

with LTE – Fiber construction cost– Synchronization in long distance

network

Scenario #2: central deployment

BSC

BBU Pool

RRUBBU BBU

BBU BBU

MSC10KM

RRU

Case in China:

World largest TD-SCDMA BBU pool

Max support 72 RRUs

Power: 400W

A city like Bangalore or Delhi could be served from <10-15 pooled sites.


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Wireless Network Cloud: Convergence of IT Platforms, SDR & RRH, Cloud Computing Principles & Fiber-to-the-tower

End-to-End IP Infrastructure in 4G

IT & Cloud Computing Techniques

BaseStation Pool

Antenna + Remote Radio Header

Fiber (> 10Km)

Software Radio Technology/

Hybrid IT Systems

Remote Radio Header Technology

GSM RF header

WiMAX RF header

WCDMA RF header

WCDMA RF header

GSM RF header

LTE RF header

Resourcemanager

Server for BS

LTE

WiMAXGSM

WiMAX

WCDMA

WCDMA

WCDMA

GSM

GSM

Server for Access GW

Timing Network over IP/Eth

Server for Access GW


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Joint processing

I

I

I

I

I

I

Multiple points collaborate to mitigate ICI or align interference for cancellation.

Multi-cell environment withfrequency reuse factor 1

Optical fiber

Optical fiber Optical fiber

interference

Wireless Network Cloud Potential: Distributed Interference Management. Eg: Collaborative MIMO for Elastic Capacity Allocation


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An e2e Demo has been setup in IBM CRL/IRL ([email protected])

Internet

RRH(USRP)

RRH(USRP)

WiMAX BS /Gateway(multi-core server)

MS (laptop simulated)

Multi-core Utilization Analysis Tool Radio Signal Analysis Tool

I-vieW

VoIP Web Browsing

Web Server

Demo Application

VoIP Stream

Web Browsing Edge Gateway

WiMAXBS

WiMAX BS

WiMAX BS

SIP Server

Soft-phone

Collaboration of IBM China and India Labs: Multiple base-stations on common IT platform, USRP & e2e flows


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BS SDR System Architecture

MAC: Software Components

RRH adaptor

...

Lo

cal S

wit

ch F

abri

c (P

CIe

Sw

itch

)

To other BS chasisTo ASN gateway or core networkTo internet directly

RRH

RRH

Signal processing server

(PHY) (P7/x86/Cell)

Lo

cal S

wit

ch F

abri

c (G

bE

sw

itch

)

Wireless MAC modules& PHY-MAC adaptors

BS edge router

Control & Manage

...

RRH

RRHRRH adaptor Signal processing

server(PHY) (P7/x86/Cell)

Prism based platform

Control & management

Switch of BS system

BS edge router

MAC instance

MAC instance

MAC instance

Adapter Adapter Adapter

Fast path data processing

Slow path message

processing

MAC and adapter Stacks

Scheduling

Fragment & packing

Packets Encryption

ConcatenationPacket Extract

Defragment & unpacking

Packets Decryption

MA

C M

anag

emen

t

DownlinkUplink

DL AdapterUL Adapter

Msg.

Msg.

Msg.

Key technical challenges being addressed (IRL+CRL)

• How to map the wireless software radio (SWR) stack/workload to massive multicore and hybrid architectures?

• How to meet QoS and real-time requirements for the VoIP application, especially since the wireless software stack (such as PHY and MAC layer) will be implemented in software using a regular OS?


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Laundry List of Challenges

Difference from regular computational, storage cloud: “real-time computational cloud”– Focus on very high performance, real-time synchronized behavior. – Cooperative techniques require greater degree of rigor in performance management– Wireless = Critical infrastructure. Availability / reliability equally important as real-time

performance support.

Choice of underlying platforms: hybrid systems, commodity servers and mapping it to VMs (eg: MAC VM may work well on system A, and PHY VM work well on system B).

– Need real-time virtual switches that can tie together such component VMs into a pipeline (Network -> MAC -> PHY)

– Cooperative techniques require redesign of protocols / implementation

Multi-tenancy, elastic provisioning of real-time resources, tracking performance / availability risks (eg: 4-5 nines)

– Providing backup for virtual base-stations from multiple data center sites: “cloud” attribute.

Helping the industry move from an integrated “box” model to a software + outsourced services model.

– Hypothesis: ARPU pressures faced by providers will ultimately drive such a move. Aggressive outsourcing happening in markets like India.


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Summary

Software radio is an emerging technology.

The long term potential of software radio involves: – Unbundling base stations into hardware, software, RF components.– Application of IT platforms, open wireless interfaces to SDR; opening up a open-

source community of developers – Allowing flexibility for BS software to be virtualized, and consolidated into pools for

reduced CAPEX/OPEX, higher utilization and change business models– Fiber to towers will allow pooling and application of the Cloud model.

Wireless network cloud can provide new benefits. – Elastic capacity allocation & higher utilization/lower costs– Distributed Interference Management: Collaborative MIMO etc (5th Generation Wireless)– Integration of edge-based services at the cloud site. Eg: caching, content delivery,

unified communications, enterprise app delivery, cloud-based application delivery etc

Perfect storm of “cloud” challenges: – Real-time, synchrony/performance-critical, ultra-high reliability requirements.


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Terminology

RAN – Radio Access Network CN – Core Network BTS – Base Station = BBU + RRU BSC – Base Station Controller BBU – Base Band Unit RRU – Remote Radio Unit RNC – Radio Network Controller, BSC in 3G NodeB – BTS in 3G eNB – Base Station Node in LTE LTE – Long Term Evolution (E-UTRAN) AIPN – All IP Network NEP – Network Equipment Provider

© 2009 IBM Corporation The Future of Software Radio: Wireless Network Cloud Parul Gupta, Smruti...

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