THE APPLICATION OF THE APPLICATION OF GPRS FOR SCADA GPRS FOR - - PowerPoint PPT Presentation

THE APPLICATION OF THE APPLICATION OF GPRS FOR SCADA GPRS FOR SCADA COMMUNICATIONS COMMUNICATIONS

Dieter Gütschow Telecommunications specialist Industry Association Resource Centre

African Utility Week, 8­10 May 2006

Overview

• Introduction
• GPRS technology
• Application of GPRS for SCADA
• Proposed GPRS architecture
• Conclusion

Introduction

• Eskom’s private mobile radio network for

SCADA

Slow data rates Limited capacity High total cost of ownership ☺ Point­to­multipoint ☺ Good geographical coverage ☺ High reliability ☺ Low terminal costs

GPRS technology

GPRS ­ General Packet Radio Service

• Supplements other data transfer methods
• 2.5G technology

2G 2.5G 3G

WCDMA 384 – 2000 kbps GSM HSCSD 43.2 kbps GSM circuit switched 9.6 kbps EDGE 384 kbps GPRS 115 kbps

GPRS technology

• Data speed

– Between 9kbps – 57.6kbps – Ave: 20­30kbps

• Immediacy

– No dial­up necessary (15s) – New session: 4­8s; “Always on”

• Robust connectivity

– Coding redundancy – Error detection – Selective retransmission

GPRS technology

• Security

– Encryption over the air – Security of core GSM network – Authentication (via SIM) – Additional authentication

• Packet Switching (TCP/IP)

– Automatic rerouting – Multiple concurrent users

• Data latency

– Variable roundtrip delays: 0.5 – 1.5s

GPRS costs

10 20 30 40 50 60

2002 2005

Year Rand / MByte

R50 / MB R2 / MB

GPRS technology

• Usage based billing

­ 96%

GPRS technology

• Geographical coverage

– 87% of land surface – 95% of towns / population

PMR vs GPRS

☺ Excellent coverage ☺ Excellent reliability Slow data rates Limited capacity High total cost of

• wnership

Simple connectivity Poor security Good coverage Good reliability ☺ High data rates ☺ “Unlimited” capacity ☺ Low total cost of

• wnership

☺ Robust connectivity ☺ High security

Application of GPRS

Technical considerations

– Connection to the GPRS network – Conversion to IP – IP address allocation – Security

BTS BTS Laptop GPRS modem Corporate Server GPRS modem PDA Firewall Corporate LAN GPRS Network Router

Option A

Application of GPRS

Technical considerations

– Connection to the GPRS network – Conversion to IP – IP address allocation – Security

BTS Laptop GPRS modem PDA SGSN GGSN Firewall Router

Internet

VPN/RAS Server Corporate DMZ LAN Firewall Corporate Intranet Corporate Internet Router

Enterprise GPRS Network VPN

Option B

Application of GPRS

Technical considerations

– Connection to the GPRS network – Conversion to IP – IP address allocation – Security

BTS Laptop GPRS modem PDA SGSN GGSN VPN/RAS Server Corporate DMZ LAN Firewall Corporate Intranet

Enterprise GPRS Network

Customer Premises Equipment Private APN

Option C

Application of GPRS

• Technical considerations…

– Support for IP

• SCADA protocols vs. TCP/IP
• Protocol encapsulation IP..[DNP3]..IP

– IP address allocation

• Dynamic vs. static IP addresses
• Static IP requires private APN, VPN,

RADIUS server

Application of GPRS

• Financial considerations

Cost Category Setup costs Monthly rental / maintenance Own Private APN and supporting infrastructure / services (50 MSISDN numbers included) R 4,500 R 5,000 Additional APN MSISDN number associations R8.77 / MSISDN APN connectivity to Corporate Application Server (64kbps) R 1,000 R 2,000 RADIUS Server R 2,850 R 3,800 Data Contract and monthly SIM card fee R200 / SIM R50 / SIM 64kbps leased line (50km) R 2,100 R 2,300 GPRS traffic charges outside of any data bundles: R2.00 / Mbyte Assumptions 3

rd party APN access per month: R30 / MSISDN

Amount of DNP3 data transacted per RTU per day: 32 kbytes

R 0 R 200 R 400 R 600 R 800 R 1,000 R 1,200 10 25 50 75 100 150 200 250 500 750 1,000 1,500 2,000

• No. of RTUs

Average monthly cost / RTU Own Private APN, Direct Leased line to GPRS network 3rd Party APN, Leased line to GPRS network Own Private APN, GPRS modem connection to GPRS network 3rd Party APN, GPRS modem connection to GPRS network

Projected GPRS costs

R70 – R90 per RTU / month

Role Players

Power Utility System Integrator GSM Network Provider Fixed line Telco Hardware / Software supplier

Proposed Architecture

HLR BSC SGSN GGSN MSC RTU RTU RADIUS Server Own or 3

rd party

infrastructure GPRS network DNP3 encapsulated DNP3 TCP/IP TCP/IP DNP3

APN: Access Point Name BTS: Base Transceiver Station SGSN: Serving GPRS Support Node GGSN: Gateway GPRS Support Node MSC: Mobile Switching Centre BSC: Base Station Controller HLR: Home Location Register RTU: Remote Terminal Unit

APN 64kbs leased line Existing SCADA Master station GSM communications server

Next steps

• Pilot system established

– Evaluate performance, reliability, risk – Determine actual cost of ownership

• Recommendations for application in

Eskom:

– Use to supplement existing systems? – Use only for back­up communications? – Use to replace existing system? – Combination of above?

Conclusion

• Features of GPRS make it an attractive
• ption for SCADA communications
• Private mobile radio:

– R810 per RTU / month – R366 / MB

• GPRS:

– R2 / MB – R109 per RTU / month

Conclusion

• Benefits:

– No new telecoms infrastructure required, immediate coverage – Low operating & maintenance cost – Access to and compatibility with new technologies e.g. EDGE / 3G – Limited risk (SLAs, capacity, standby capacity) – Other applications e.g. AMR, mobile computing, prepaid vending

Conclusion

SA financial and retail institutions are successfully using GPRS for EFT and credit card authorisations Will SA power utilities follow… and apply it for SCADA and

• ther applications?