concepts to reality e-mail: [email protected] nick smye 15 february 2000 presentation to tetra...
TRANSCRIPT
Concepts to Reality
e-mail: [email protected]
Nick Smye
15 February 2000
Presentation to
TETRA BUSINESS SYSTEMS GROUP
AN INTRODUCTION TO THE PEI
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FORMAT
1. Introduction to Mason Communications
2. Radio Peripheral Interfaces
3. PEI Overview
4. AT Command Set
5. PPP/TNP1 Command Set
6. Current Status of PEI
7. Conclusion
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INTRODUCTION TOMASON COMMUNICATIONS
• Telecoms and IT Consultancy
– What is our TETRA Experience?
• Worked with Home Office on PSRCP since 1994
– Business Case Phase
– Project Definition Study Invitation to Tender
– User Service Level Requirements
– Project Definition Study Phase
• Greater Manchester Police - Business drivers for
TETRA
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INTRODUCTION TOMASON COMMUNICATIONS
• Lancashire Constabulary - Pilot Assurance Support
• States of Jersey Police
– Validation of pilot system
– Re-validation after upgrade
• European GSM Operator – assistance with RFP to support a Public TETRA Licence Bid
• Technical Advisers to PITO
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RADIO PERIPHERAL INTERFACESRadios and Peripherals
• In early days (pre-trunked), professional radios tended to be specialised and expensive
• Peripherals limited and manufacturer specific
– Remote microphone
– Earphones/Headsets
– Speakers
• Some peripheral specialists
– Products ordered to a specific interface (££ + time)
– E.g. Handsfree mic
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RADIO PERIPHERAL INTERFACES Trunked Radio
• Introduction of trunking with standard and open systems (MPT 1327/MPT1343)
• Radio offers access to powerful new functionality (speech+ status/short data/data)
• System performs Dynamic Channel allocation
• Applications are now able to to use these features…plus access to radio
• BUT.. How do we access these features in a non-proprietary manner?
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RADIO PERIPHERAL INTERFACES MAP27 Interface Standards
• Initially some manufacturers used proprietary interfaces
– Applications manufacturer specific
– Fleets with more than one manufacturer
• Open standard, MAP27, published in 1992
• Most manufacturers support it
• Defined interface (RX,TX GND) and Layered Protocol
• Data Link Layer uses a block format, delimited by control characters
• Allows simultaneous operation (e.g. RSSI check during a data call)
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RADIO PERIPHERAL INTERFACESMAP27
Physical Layer
Terminal Radio
Network Layer
Network Layer
• Status
• Short Data
• Voice and NPD
• Modem Call
• Connection Clear
• Diversion
• Radio Control
Data Link Layer
Data Link Layer
• Blocks delimited by Control Characters
• Provides Block Transport
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RADIO PERIPHERAL INTERFACES What is the GSM Approach?
Base GSMGSM 07.07
SMSGSM 07.05
GPRSGSM 07.60
PPP command Based
All AT command Based
• Call Control• Network Service• Mobile Equipment Control and Status
AT and Block
• Message Retrieval and Transmission• Hex Encoded Binary• Block mode – similar to MAP27
• X25• PPP• IHOS• AT• PPP Dial In Compatibility
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PEI OVERVIEWTETRA – Open Standards Based
Architecture
I4
I4’
GATEWAYSOMC
BSSNSS
TETRA 1
PSTNISDN
PTNPDN
DEFINED INTERFACESI1 Radio air interfaceI2 Line station interfaceI3 Inter-system InterfaceI4 Terminal equipment interface (MS & TE)I4’ Terminal equipment Interface (LS & TE)I5 Network Management InterfaceI6 Direct Mode radio air interface
I1I2
TETRA 2I3
NetworkManagement
NetworkManagement
I5I6
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PEI OVERVIEW Peripheral Equipment Interface
• Defined Standard for access to:
– Data
– Set-up and Control of Voice Calls
– Radio Specifics (e.g. battery status)
– User Applications in Radio
• Standard Physical Interface (?)
• Minimal Extra Software in Terminal ( Driver)
• Max compatibility with GSM
• Still in draft
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PEI OVERVIEW Physical Connection
• Physical layer V24/V28
– D type (RX,TX,GND)
– RJ11/RJ45
• Other Serial Form Physical Layers can be used where Appropriate
– Infrared (GSM?)
– Ethernet
– Bluetooth?
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AT Commands PPP Commands
PEI PROTOCOLS
PEI OVERVIEW PEI PROTOCOLS
Short Data
Circuit Mode Data
Radio Functions
IPv4
IPv6
Packet Data
Speech CC
SDS
Radio Config & Status
Supplementary Services
CM Data
Radio Remote Control
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AT COMMAND SETCommands
• AT Commands well known in Industry
• “+C” prefix reserved for Digital Cellular
• PEI AT Commands Based on:
– Cellular DCE Control
– PCCA Wireless Modems
– TETRA Specific
– SDS (very similar to GSM)
– Radio Control
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AT COMMAND SETTypical Applications
• Those suited to small data transfers using TETRA SDS
– Type 1 – 16 bit
– Type 2 – 32 bit
– Type 3 – 64 bit
• Type 4 – up to 2039 bits (Advanced Link recommended for user data longer than approx. 133 Octets)
• Short Data Transfer Layer (SDS-TL)
– Built on top of SDS Type 4
– Provides end to end acknowledgment
– Store and Forward
• Typical Application - AVL
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AT COMMAND SETLimitations
• Terminal is either in Command State or On-line Data State
– In On-line Data state, no other communication with radio is possible (e.g. battery state)
• Usefulness is limited to SDS, Circuit Mode Data
– What support for CM data?
• No current support for voice calls
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AT COMMAND SETAdvantages
• Simple to implement
• No need for TCP/IP stack and PPP layer
– Reduces terminal’s complexity, memory requirement
– Reduced Power consumption
• Easy to debug
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PPP/TNP1 COMMAND SETWhat is PPP?
• Point-to-Point Protocol
• Standard Internet (IETF) Open Protocol
• Standard method of transporting multi-protocol datagrams over point-to-point links
– Method for encapsulating multi-protocol datagrams
– Link Control Protocol for establishing, configuring and testing the link
– Family of Network Control Protocols for establishing and configuring the Network Protocols that run over PPP
• THE standard for PCs for dialup internet (IP) access
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PPP/TNP1 COMMAND SET PPP Frames
• 0xC021 Link Control Protocol – establishes, maintains and ends PPP
• 0x0021 IP Protocol
• 0x8021 Internet Protocol Control Protocol – establishes configures and terminates the TCP/IP session
• 0x0287 TETRA Network Protocol 1
• 0x8287 TETRA Network Protocol 1 Control Protocol
Frame Start Frame EndProtocol DATA Padding FCS
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TNP1
PPP/TNP1 COMMAND SET PPP Mode Structure
LCP
TCP/IP
IPCP
PPP Frame
TNP1CP
PPP Frame
PPPPPP FramePPP
RS232
NetworkLayer
Data LinkLayer
DATA RADIO CONTROL
User Terminal
RADIO
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PPP/TNP1 COMMAND SET IP Protocol
• IP provides the means of transporting the application data
• IP is universally used
• IPv4 and IPv6 Supported by PEI Specification
• Provides for standard interconnection at the SwMI to external IP networks (e.g. host computer) via router/gateway
• BUT not as efficient as SDS for transfer of short messages
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PPP/TNP1 COMMAND SET TNP1 Protocol
• This provides the means of setting up calls and controlling the radio
• No equivalent functionality in existing Internet Specifications and so this is unique to TETRA
• Uses standard PPP frames with a TNP1 Protocol number (0x0287)
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PPP/TNP1 COMMAND SET TNP1 Commands
• Radio Control and Call set-up
– Priority
– Group Attachment
– SDS
– Duplex/half duplex
– Energy Saving Mode
– Etc.
• Allows proprietary defined information to be sent and received from radio
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PPP/TNP1 COMMAND SET TETRA PEI PPP Issues
• PPP must be used for TETRA Packet Data Services
• No manufacturers are currently supporting IP packet data
• PPP/TNP1 complex to implement in radio and terminal
– Memory
– Power consumption
– Development effort
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CURRENT STATUS OF PEI
• Still under draft
• Complex standard – TETRA MOU have proposed a subset of the AT commands
• PPP/TNP1 support awaiting rollout of Packet Data?
• What is the current level of support?
• Are all manufacturers going to support it?
• Will the widespread adoption of GPRS influence TETRA?
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CONCLUSION
• PEI Standard defined for TETRA Terminals
• AT and PPP modes
• AT simple and suited to small data requirements
• PPP complex but powerful – the only choice for packet data
• What is the support from the manufacturers and the timescales?
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• Military
• No access to CODEC
• SDS-TL
• IP overhead vs SDM?
• AT/Radio turnon
• Suppl Serv?
• Voice call using AT?
• IP When
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CASE STUDY -Public Safety Radio Communications Project
• Business Case Phase
– Evaluation of suitable systems
– Technical input to Business Case
• Project Definition Study Invitation to Tender
– Functional Specification
– Terms of Reference
• User Service Level Requirements
– Service Level Template and Guide
• Project Definition Study Phase
– Ongoing review of Study Products
– Review of FDS and Operational Trials.
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PUBLIC SAFETY RADIO COMMUNICATIONS (PSRCP) PROJECT
• Home Office - Technical Advisers
• Greater Manchester Police - Business drivers for TETRA
• Lancashire Constabulary - Pilot Assurance Support
– Terminal & Peripheral Equipment
– Integrated TETRA Radio & Telephony
• Hampshire Police - Impact of PSRCP Appraisal
• Cheshire Constabulary - Assurance Support.
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PUBLIC SAFETY RADIO COMMUNICATIONS (PSRCP) PROJECT
• Home Office - Technical Advisers
• Greater Manchester Police - Business drivers for TETRA
• Lancashire Constabulary - Pilot Assurance Support
– Terminal & Peripheral Equipment
– Integrated TETRA Radio & Telephony
• Hampshire Police - Impact of PSRCP Appraisal
• Cheshire Constabulary - Assurance Support.