P25 Trunked System Overview for Radio User Train-the-Trainer

Training Session Notes

Contents

What is P25?

M/A-COM P25 Terminal Equipment Call Types Unit ID’s Call Processing Emergency Calls Group Scanning ProScan Terminology ECP3078A page 3

What is P25?

Interoperable digital radio system standard Intended for all public safety LMR bands (VHF, UHF, and 800 MHz) Developed Jointly by: – TIA – Association of Public-Safety Communications Officials (APCO) – National Association of State Telecommunications Directors (NASTD) – Various agencies of the Federal government (FED) in the early 90’s to improve spectral efficiencies.

TIA/EIA Standard in 1999. Under TIA/EIA-102 ECP3078A page 4

Project 25 Benefits

Key benefits sought by the user community: – Competitive procurement of equipment – Interoperability of equipment – Spectrum efficiency – User-friendly operation equivalent to today's public safety equipment and common across all bands, system configurations, services, and manufacturers.

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Project 25 Features

Key voice features – IMBE vocoder – Group and Individual calls – Telephone interconnect – Emergency – Encryption (DES, AES) – Console dispatch – Preempt – OTAR (Over-the-Air-Rekeying) Packet switched IP backbone – Full control of the system and radios – Interoperability - network level and radio level – Group, individual, emergency calling ECP3078A page 6

Some P25 System Basics

Each Radio: – Unique Unit ID – One or More Systems (sites) – One or More Talk Groups (Group ID) Talk Group: – A ”Logical” Collection of Units – Unique Group ID Capacities: – 16,777,216 Unit IDs – 65,536 Group IDs TRAINING TRNG 1 ECP3078A page 7

P25 Portable Radios

P7170 (System Model) P7150 (Scan Model) P7130 (Select Model) P5150 (Scan Model) P5130 (Select Model)

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M7100 Mobile Radio

Hand-held Controller System Control Head Scan Control Head

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P25 Terminal Features

P25 Group call transmission/reception Talk group identification Group call alert P25 Individual call transmission/reception Individual identification (PTT ID) Emergency and Emergency Indication Priority Scan Carrier control timer (CCT) Transmit lockout Up to 256 conventional channel capacity ECP3078A page 10

Call Types

Voice Calls – Group Calls • Normal • Emergency • Announcement Groups – Individual Call • Unit to Unit – System All Call Radio displays Group and Caller ID for each call ECP3078A page 11

Unit Identification

Unit ID – Uniquely identifies radio to system – 24 Bits – 16,777,216 Possibilities (0 - 16,777,215) – Only allow 1 – 9,999,999 – Must be programmed into radio – Allows Individual Calling – Allows Call Tracking ECP3078A page 12

Conventional vs. Trunked

Computerized Assignment of Channels

Conventional

Service Counter

Trunked

Service Counter

Service Employee Customer ECP3078A page 13

Call Processing

Mobiles / Portables continuously monitor Control Channel Operator makes selection, depresses PTT, and transmits a Channel Request message Channel Request received by Control Channel System validates request against the Group and Unit databases Control Channel responds with Working Channel assignment Units switch to the assigned Working Channel – Calling Unit is now ready to talk, caller can be advised by a grant tone “beep” to start talking – Working Channel adds messages to voice signal that provides for extracting units from calls – Control Channel continues to send update messages to provide late entry for other units ECP3078A page 14

Call Processing (cont.)

Calling unit releases PTT and sends Channel Release message Working Channel sends Channel Drop message out to all units All units return to Control Channel Channel Access – If Channel Request is valid, Control channel will assign the call to a Working Channel – If Group or Individual ID is not properly programmed into system, Call is denied – Network Switching Server (VNIC) will route the call to other systems as necessary ECP3078A page 15

Call Processing Exceptions

Call Queued – All channels are assigned to other calls – Automatically placed in queue for next available Working Channel – Queuing priority determines order of channel assignment Call Denied – System programming does not allow request

?

– Out of range of Control Channel

?

– Retry in different location System Busy

?

– System programming can not complete call at present time – Individual call to busy radio

?

?

– Retry later ECP3078A page 16

Emergency Call Processing

Emergency button on mobiles and portables initiates emergency call or emergency alert Elevates talkgroup to emergency status Dispatcher notification through console Other radios listening to talkgroup are notified with an audible alert Group call – Requests access for a high priority Emergency call – Flags Consoles and other units in group with *RX EMER* – Identifies caller Clearing an Emergency – Return group to normal status – Radio must be programmed for Clear Emergency ECP3078A page 17

Group Call Scanning

Radio is able to monitor multiple groups Radio can only receive one group at a time Responding to a call (programmable) – Selected group – Scanned group (within timer period) Scan groups on Scan List – Fixed list in programming – Programmable by user Scan Control – Fixed in programming – Controlled by user Priority 1 Group Priority 2 Group Group 1

?

Group 2 ECP3078A page 18

How Far Does it Cover?

???

Many factors affect coverage: Site Location Urban clutter (+ & -) Reflections / Multipath (+ & -) Ducting over water (+) Wet pine needles (-) Weather (+ & -) Frequency (+ & -) Earth curvature Many others… (+ & -) ECP3078A page 19

ProScan

Site 1 Site 2 Network Switching Center Enhanced System Scanning Feature (compared to WASS): – Algorithm Based on Received Signal Strength Indicator and CC Verification – Scans after Signal RSSI Drops below a User Defined Threshold – Searches for new System Based on Defined Adjacent System Scan List – Switches to new System, if User Defined Criteria is Met – Provides Better Audio Quality ECP3078A page 20

Radio Programming

Every M/A-COM P25 radio is programmed with a personality.

A Data file: – Directs the operating characteristics of the radio – Interfaces the radio to a system This personality is what makes a radio unique to the user of the radio.

Programming Cables TQ 3392 – P7100, P5100 TQ 3409 – M7100 (Shop) TQ 3410 – M7100 (Field) TQ 3419 – P7100, P5100 (without TQ 3370 interface)

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C3 Maestro

IP

Dispatch Consoles

Purpose: Monitors & controls multiple Groups at a single physical position A single Microphone/PTT and Selected & Unselected Speakers Adds Patch & Simulselect capability to the P25 System Provides EMERGENCY control Physically: Can be programmed with 112 Groups Simultaneous audio based on Talk path licenses – Standard – 4 talk paths – Maximum – 20 talk paths ECP3078A page 22

Terminology

AES CAI CNM CTCSS DES DVU FDMA GWB IMBE IP Advanced Encryption Standard (256 bit encryption) Common Air Interface Centralized Network Manager Continuous tone coded squelch system Digital Encryption Standard (56 bit encryption) – Type III or DES-OFB Digital Voice Unit Frequency Division Multiple Access Gateway Board; OpenSky term for the Interoperability Gateway DVU board Improved Multiband Excitation – 3rd generation voice encoder developed by Digital Voice Systems, Inc.

Internet protocol ECP3078A page 23

Terminology

KMF LMR MDIS MES MME NAS NMC NOC NSC NSS P25 Key Management Facility Land Mobile Radio Mobile Data Intermediate System; software on the NSS Mobile End System. Mobile or portable.

Miniature Mobility Exchange Network Administration System Network Management Console. Previous name for RNM Network Operations Center Network Switching Center Network Switching Server APCO Project 25; a standard Common Air Interface protocol for radio operation and system interface specifications developed by TIA to provide for interoperability of different manufacturer’s equipment ECP3078A page 24

Terminology

PSTN PTT RF RNM RX SitePro SMI TDMA TX UAS VES VNIC VoIP Public Switched (or Service) Telephone Network Push-To-Talk (depressing the radio transmit key) Radio Frequency Regional Network Manager Receive or Receiver SitePro Controller (controller for each repeater station) Site Management Interface; software installed on the Network Sentry Time Division Multiple Access Transmit or Transmitter Unified Administration System Voice End System. User.

Voice Network Interface Controller, software on the NSS Voice over IP ECP3078A page 25