dmr protocol introduction prepared by: samuel chia date: 08-apr-2009

DMR Protocol Introduction

Prepared by: Samuel ChiaDate: 08-Apr-2009

Motorola Document Classification, File Name, Rev NumberAdd additional legal text here if required by your local Legal Counsel.

MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005

Content

1) Introduction

2) Benefits of DMR Protocol

3) System Configuration

4) Channel Structure

5) Modulation

6) Operational scenarios

7) Burst Format

8) Protocol specs

9) Possible improvements



IntroductionWhy DMR was pursued?

1)Declining Indirect market business. Create new business to churn analog based systems.

2)Mandate by FCC that non frequency efficient (>= 12.5kHz equipment) will not be approved after 2005 due to congestion. However we now know that it has been postponed to 2011. And all Public safety equipment has to be migrated by 2013.



IntroductionProtocol Development History

2001 – Evaluation of DIIS (intended ETSI DMR protocol).

2002 – Draft a new 4FSK TDMA protocol (F2) for APCO P25 and DMR. Goal is to use for both products.

2003 – Protocol Prototyping start.

2004 – Start Product Development.

– Start F2 protocol standardization with ETSI(Goal: Define the air interface. Define minimum set of voice and data features)

2005 – F2 Approved by ETSI and included in DMR First Version

2007 – First DMR Product Ship Accepted



Benefits of DMR Protocol1. Spectrum efficiency via TDMA

1. 2X users, capacity and throughput

2. Allows 2 simultaneous calls through 1 repeater

2. Improved basic capabilities

1. Range improvement

2. Increased audio quality – ”Noise Cancellation and Digital Voice”

3. Improved battery life (Improve from 8 hours to 12 hours)

4. Enhanced Features (Test Messaging and Better Call handling)

Slot 1 Slot 2



Spectrum Efficiency via TDMA

12.5kHz Channel 12.5kHz Channel

12.5kHz TDMA• Divides existing channel into

two timeslots• Delivers twice the capacity

through the repeater• Performance is same or better

than 12.5kHz FDMA• 1 repeater does work of 2; also

reduces combining equipment• ETSI Tier 2 Standard for

licensed bands• Enables 40% increase in radio

battery life

frequency

time

12.5kHz Channel

Regulatory emissions mask

Slot 1Slot 2

Slot 1Slot 2

Slot 1

6.25kHzSub- Channel

6.25kHzSub- Channel

Slot 2

Slot 1

12.5kHz FDMA• Today, Analog• 1 voice for each 12.5kHz

channel• 1 repeater for each channel

6.25kHz FDMA• Could squeeze into 12.5kHz

channels but with reduced power.

• Performance degraded • reduced range• more interference

• Need 1 repeater for each sub-channel; cannot combine repeaters to share antenna site

• ETSI Tier 1 Standard for licensed bands



Improved Digital Audio Quality and Range

- Clearer voice over a greater rangeDigital error-correction technology permits audio and digital communications with no loss

- Improved rangeImproved audio above min acceptable quality provide better range performance.

- Static and noise rejectionDigital receivers reject any error signals, permitting improved audio in loud environments

Excellent

Poor

Audi

o qu

ality

Strong WeakSignal strength

Minimal acceptable audio

Digital audio

Analog audio

Improved audio



Increased Audio Quality1) AMBE++ is a proven vocoder to

have significant improved audio quality compared to Analog 25kHz channel. For a 12.5kHz channel, the MOS would be expected to be lower.

2) Noise Suppression technology is built into the vocoder which will improve audio quality in noisy environment. This gives significantly better background noise immunity compared to analog systems which has limited noise suppression capability.

MOS – Mean Opinion Score



Improved Battery Life

5/5/90 Duty Cycle

TDMA Tx is 30ms ON and 30ms OFF. This means that Tx current is about half of what it is in FDMA

40% Battery Life Improvement with TDMA



One-to-All

Allows all on the same channel to

hear communications

Enhanced Features – Digital Calling and Signaling

One-to-One

Call and talk privately with a

specific user’s radio

One-to-Many

Enables communication with

specific sets of group members

NOTE: This also applies to Text Messaging where a user can type a message and send to the intended recipients.



System Configurations

Up-link

Down-link

Up-link

Down-link

To other systems To PSTN/Intranet/Internet

f1

f1f1 f1

f1

Direct Mode Configuration

Repeater Mode Configuration



12

System Configurations

DMR uses a 2:1 TDMA protocol, allows more conventional system configurations than a FDMA protocol. The following modes being used:-1. 12.5e repeater mode - Slot 1 use for voice, Slot 2 use for data

2. 6.25e repeater mode - Both slot 1 & 2 use for voice or data (Slot 1 user cannot use Slo2 and vice versa)

3. 12.5kHz direct mode – Only one slot is being used. One call per 12.5kHz bandwidth.

(There are future intended operations which I will discuss in later slides)



Channel Structure (Repeater)1. Example of 2 simultaneous voice

call on one repeater

2. Outbound signaling is labeled “BS Tx” and inbound signaling is labeled “MS Tx”.

3. As shown figure the outbound channel contain a CACH (Common Announcement Channel)

1 1 1 1 1 12 2 2 2 2 2 1 21 1 1 1 1 12 2 2 2 2 2 1 21 1 1 1 1 12 2 2 2 2 2 1 2

1 1 1 1 1 12 2 2 2 2 2 2 11 1 1 1 1 12 2 2 2 2 2 2 11 1 1 1 1 12 2 2 2 2 2 2 1

MS TX

BS TX

TimeTime

TDMA burst(30 msec)

TDMA frame(60 msec)

Guard TimeGuard Time

CACHCACH Sync/EmbeddedSync/Embedded

Repeater

Slot 1 Freq. 1

Slot 2 Freq. 2Slot 2 Freq. 1

Slot 1 Freq. 2



Channel Structure (Direct Mode)

1. Example of 1 subscriber calling another in direct mode

Subscriber 1 Slot 1 Freq 1

Subscriber 2 Slot 1 Freq 1

LCHdrLCHdr

VoiceVoice VoiceVoice VoiceVoice Voice VoiceVoiceVoiceVoice VoiceVoiceVoiceVoice

Time



4FSK Modulation for 12.5 kHz Channel Bandwidth

Modulation Type: 4 FSK, 4 level Frequency Shift Keying

Bit Rate: 9600 bits/second

Deviation index h=0.27 Symbol 01 = 1.944 kHz

Symbol 00 = 0.648 kHz

Symbol 10 = - 0.648 kHz

Symbol 11 = -1.944 kHz

Modulation



Modulation (Power Profile)

+4 dBc

0 Watts

Slot Boundary

1.5ms

+1 dBc

-3 dBc

0 dBc

TTR Timing signal from OptA_Sel3

27.5ms, Td(132 valid data symbols)

Slot center

(1.5ms)

Ts1

Slot Boundary30ms

-1 dBc

Antenna Switch turned off here

Te1

1.25ms 6symbol period

-60 dBc

Antenna Switch turned on here

Ramp down starts

-57 dBm

TsTe



Modulation (Power Profile)

27.5ms data

1.5ms ramp up /down

2.5ms guard time

Slot 1 Slot 2

30ms

1) This is a transmission of 2 radios in repeater mode. 2) The guard time specified is for slots power ramping

and also Time Advance scenarios.



Super Frame with Header & Terminator

A B C D E FVH VT…

1 Super Frame

Voice Call Scenario

Voice calls start with a Voice Header to allow the receiving party to sync and determine if the call is to the intended recipient.Then the voice data is transmitted in the superframes.Voice Terminator indicated end of voice call. It must be sent after a voice superframe is complete.



Voice Super Frame (Direct mode)

A B C D E F

48 bit sync pattern Emb LC (32 x 4 bit) Null(32 bit)

Voice Call Scenario

The first burst of a superframe contain a sync burst. This allows late entry calls.Embedded LC is sent in the next 4 burst. This LC contains the source ID, destination ID and call type.The null burst does not contain any embedded signaling data.



Each Voice Frame (VF) = 20 ms (72 bits)

Each Slot will contain 3 VF

A F C D F F AB E F

VF1 VF2 VF3

60 mS

30 mS

AMBE+2 Encode

AMBE+2 Decode

Voice Call Scenario



2 1 1 1 1 1 1 12 2 2 2 2 2 2 1 22 1 1 1 1 1 1 12 2 2 2 2 2 2 1 2

Time

DataBlockDataBlock

DataHdrDataHdr

DataBlockDataBlock

DataBlockDataBlock

DataBlockDataBlock

DataBlockDataBlock

DataBlockDataBlock

DataBlockDataBlock

DataBlockDataBlock

LastBlockLastBlock

Data transmissions do not carry embedded LC information (always sync) Confirmed and Unconfirmed data send

HeaderData BlocksLast Data Block

Confirmed Data ResponseHeader Data Blocks (Only if destination requests retransmission of blocks that failed block CRC)

Data Call Scenario



Data Message Decomposition

Message broken up into fragments Data Packet composed of

Data HeaderMessage/Fragment data

IP datagram of arbitrary length

Fragment 1

Block 1 Hdr Block Block m

Break into blocks

Time

1 122 2 1 12 2

Fragment n Fragment 2

Break into fragments

…..

….. Block m is the lastdata block of a fragment

Building a data packet,which may havetwo header blocks

Data Call Scenario



Individual Call via repeater

HdrHdr

1 1 1 1 1 12 2 2 2 2 2 2 1

MS1 TX

Repeater TX

1 1 1 1 1 12 2 2 2 2 2 1 2

MS2 TX

TimeTime

1 1 1 1 1 12 2 2 2 2 2 1 2

ACKACK

VoiceVoice VoiceVoiceAlertReq

ACKACKAlertReq HdrHdr VoiceVoiceIdleIdle IdleIdle IdleIdle IdleIdleIdleIdle IdleIdle IdleIdle IdleIdle IdleIdle IdleIdle

This is a case of one subscriber making an individual call to another subscriber.Request and ACK are Data Bursts (Data Slot Type = Control)Voice Header is a Data Burst (Data Slot Type = Voice LC Header)

Repeater Voice Call Scenario



Burst Structure (Generic)

30 msec (288 bits)

27.5 msec (264 bits)

Burst Contents Burst ContentsSync or

EmbeddedSignaling

Gua

rd/C

AC

H

Gua

rd/C

AC

H

D

VoiceBurstVoiceBurstVoiceBurstVoiceBurstVoiceBurstVoiceBurst

D

LCHrd

Data Sync

LCHrd

Data SyncData Sync

Superframe = 360 msecSuperframe = 360 msec

VoiceBurst

Voice Sync

A

VoiceBurst

Voice Sync

VoiceBurst

Voice SyncVoice Sync

A C

VoiceBurstVoiceBurstVoiceBurst

C E


EBB


F


VoiceTerm

Data SyncData Sync

VoiceTermVoiceTerm



Subscriber Inbound TX TDMA Frame in Repeater Mode

TDMAburstcenter

SYNC or embeddedsignaling

PayloadPayload

TDMAburstcenter


PayloadPayload

30,0 ms 30,0 ms

TDMA frame

Timeslot 1 Timeslot 2

2,5 ms

Subscriber #1 Subscriber #2

Burst Structure (Rptr Inbound)



Repeater Outbound TX TDMA Frame


PayloadPayloadSYNC or embeddedsignaling

PayloadPayload

TDMAburstcenter

TDMAburstcenter

CACHburstcenter

CA

CH

CA

CH

CA

CH

CA

CH

CA

CH

CA

CH

30,0 ms 30,0 ms

TDMA frame


2,5 ms

Burst Structure (Rptr Outbound)



Generic Burst With Sync

Inbound/outbound sync patternsVoice/data sync patternsReverse channel sync pattern

5.0 msec5.0 msec

PayloadPayload

48 bits48 bits

SyncSync

27.5 msec27.5 msec

Inbound Voice Sync PatternOutbound Voice Sync PatternInbound Data Sync PatternOutbound Data Sync PatternReverse Channel Sync Pattern

• Direct Mode uses only Inbound Sync Patterns• This is one of the essential Patents by Motorola.

Burst Structure (Generic Sync)



Vocoder DVSI AMBE+2 (Enhanced Half Rate)3600 bps for voice + FEC

2450 bps voice1150 bps FEC

Three 20 msec vocoder frames per Voice Burst60 ms audio per burst

Voice Burst with Sync

Frame 1 (72) Frame 2 (36) Frame 2 (36) Frame 3 (72)

VC1 VC2 VC3Vocoder Frame 1 Vocoder Frame 2 Vocoder Frame 3

27,5 msec

SYNC (48)

Burst Structure (Voice w/ Sync)



Voice Burst With Embedded Signaling

EMB (Embedded Framing)CC (Color Code) – Differentiates signaling that originates at another site PI (Privacy Indicator) – Status of scrambling/encryptionLCSS (LC Start Stop) – Indicates that this burst contains the beginning, end, or continuation of embedded signalingParity – FEC Parity bits for EMB field

Embedded Signaling - Call type, Source and Destination IDs (Link Control information)

27,5 ms

CC PI LCSS

EMB Parity

Voice (108) Voice (108)Embeddedsignaling (32)

EM

B (

8)

EM

B (

8)

Burst Structure (Voice w/ Emb)



Data/Control Burst

Slo

t Typ

e (1

0)

Slo

t Typ

e (1

0)

Info (98) Info (98)SYNC orembeddedsignaling (48)

27,5 ms

Data TypeCC

FEC Parity

FEC Parity

Info – Data or control payload + FECCC (Color Code) – Differentiates signaling that originates at another siteData Type – Indicates the type of control or data that is being carriedFEC Parity – Golay (20,8) FEC Parity bits for Slot Type field

Voice LC Header

Terminator with LC

Control Block

Data Header

Rate ½ Data

Rate ¾ Data

Idle

Burst Structure (Data/Control)



Info (98)Info (98) Info (98)Info (98)SYNCSYNCS

lot T

ype (

10)

Slo

t T

ype (

10)

Slo

t T

ype (

10)

Slo

t T

ype (

10)

Interleaver

BPTC(196, 96) Encoder

Interleaver

BPTC(196, 96) Encoder

InterleaverInterleaver

BPTC(196, 96) EncoderBPTC(196, 96) Encoder

CSBK (96)CSBK (96)

27.5 msec27.5 msec

Burst Structure (CSBK)

96 bit CSBK (80 bits of signaling + 16 bits of CRC) can be carried in a single data/controlUse for radio command such as Radio Check, Radio Uninhibit/Inhibit, Call Alert and Radio Unit Monitor.



AT (Access Type) – Indicate whether slot is busy or idleTC (TDMA Channel) – Indicates whether inbound and outbound burst is channel 1 or 2LCSS (LC Start Stop)– Indicates that this burst contains the beginning, end, or continuation of CACH signalingCACH Signaling (4 CACH) – This contains a Short LC burst for scan time improvement.FEC – FEC Parity bits for CACH Burst

Outbound burst

30,0 ms 30,0 ms

TDMA frame

CA

CH

CA

CH

(24

)

CA

CH

CA

CH

(24

)

CA

CH

CA

CH

(24

)

Outbound burst

AT TC LCSS FEC

CACH signaling

Burst Structure (CACH)



Protocol Specifications 1. Bandwidth: 12.5kHz2. Modulation Type: 4FSK (4 level Frequency Shift Keying)3. Channel Type: 2-Slot TDMA.4. Data rate: 9600 bits/second5. Single slot protocol data rate outbound: 4800 bits/second6. Single slot protocol data rate inbound: 4400 bits/second7. Single slot voice data rate (Voice with FEC data rate): 3600

bits/second8. Single slot raw data payload rate: 1600 bits/second.9. Audio Throughput Delay: ~400ms10. System Access Time:

• Group Call, Direct Mode, With TPT = ~600ms• Group Call, Repeater Mode, With TPT = ~1000ms• Individual Call, Direct Mode, With TPT = ~1100ms• Individual Call, Direct Mode, With TPT = ~1500ms



Audio Throughput Delay

1. The cause of the delays is purely in the software. It can be due to buffering delays and encoding and decoding delays due to the chosen protocol. The DMR protocol is expected to have a much longer audio throughput delay compared to Analog systems.

2. The Analog System Delays can be in the order to 20 to 40ms. However the Digital System Delays can be in the order of 300ms to 500ms. This large delays is mainly due to the slotting of the voice and also the voice compression adaptation time.

Press PTTTalk Permit Tone

Audio (1kHz Tone)

Tx

Audio (1kHz Tone)

Rx

Audio Throughput Delay



System access time

Press PTTTalk Permit Tone

Audio (1kHz Tone)

Tx

Audio (1kHz Tone)

Rx

System Access Time



Possible Future Improvements



Reverse Burst Transmission

TimeTime

1 1 1 1 1 1 1 1

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

TXTraffic

Tx Radio

Rx Radio

Tx Reverse Burst

1. Rx radio is able to Tx a short burst of control information to the Tx radio.

2. This burst can be used for feature like Tx interrupt, Rx Ack, Power control…..



Reverse Burst Power

• The instantaneous power must be contained within the mask

• Since the slot is only 10ms, there will not be any risk of inter-slot interference.

+1 dBp

+4 dBp

-1 dBp

0 Watts

2.5 ms2.5 ms

2.5 ms

Region A Region CRegion B

Slot Center

2.5 ms

5 ms



Single Frequency Repeater System

Only one 12.5kHz B W channel for inbound and outbound traffic

Tx on one slot, repeated on other slot



Full Duplex Calls

1. Full duplex calls is where it operates like a hand-phone where the Tx and Rx audio is going on simultaneously.

2. This will require Slot 1 to be used as Tx and Slot 2 to b used as RX.

3. However in doing this, the Tx to Rx time is only 2.5ms and thus is too short to allow the HW locking to happen. This is currently not possible with current HW technology.

TDMAburstcenter


PayloadPayload

TDMAburstcenter


PayloadPayload

30,0 ms 30,0 ms

TDMA frame


2,5 ms



Direct Mode 2-Slot operation

uC RF

Radio Unit (A)

30ms

1. The DMR protocol does support 2 simultaneous calls in direct mode operation.

2. This new operational feature is an addition to the DMR protocol to overcome this limitation.

3. Basically, when A is transmitting to B, Radio C will also be able to transmit to D after locking on to radio A’s timing.

RF uC

Radio Unit (B)

uC RF

Radio Unit (C)

RF uC

Radio Unit (D)

Radio C user

presses PTT



Pseudo Trunk Operation

uC RF

Radio Unit (A)

30ms

Rptr

30ms

Busy Busy BusyIdle Idle

RF uC

Radio Unit (B)

uC RF

Radio Unit (C)

uC RF

Radio Unit (D)

1. In the defined DMR protocol, the radios will be allocated to a specific repeater slot and only use that slot even-though the other slot is not busy.

2. This new protocol is to allow radios to utilize any slot number if it is idle (No Activity).

3. Imagine Radio A is transmitting a private call to radio B.4. Radios in the vicinity of the repeater (C and D) will see that there is a Idle slot

and can decide to use it.



Conference Call (DGNA)

1. Another feature that is planned to be included in future products is a new calling mode.

2. This new calling mode will allow a use to specifically select a couple of radio users to be re-allocated to a temporary group ID to have a call.

3. This mode of operation is like a Skype conference call when you can select a couple of people to join a voice call.

Send temporary regrouping to selected target radios.

dmr protocol introduction prepared by: samuel chia date: 08-apr-2009

Documents

local legal counsel

etsi dmr protocol

us patent trademark

service names

respective owners

introductionwhy dmr

product development

khz channel12