1、TIA/EIA TELECOMMUNICATIONS SYSTEMS BULLETIN Enhanced Digital Access Communications System (EDACS) Digital Air Interface for: Channel Access, Modulation, Messages, and Formats TSB69.3 APRIL 1998 TELECOMMUNICATIONS INDUSTRY ASSOCIATION TEL ECOMMNICATIONS . Elcctronlc Industrlcr Alliance NOTICE TLA/EIA
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5、oes not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the Standard, Publication, or Bulletin. Technical Bulletins are distinguished from TIA/= Standards or Interim Standards, in that they conain a compilation of engineeg data or information
6、useful to the techical community, and represent approaches to good engineering practices that are suggested by the formulating committee. This Bulletin is not intended to preclude or discourage other approaches that simiiarly represent good engineering practice, or that may be acceptable to, or have
7、 been accepted by, appropriate bodies. Parties who wish to bring other approaches to the attention of the formulating committee to be considered for inclusion in future revisions of this Bulletin are encouraged to do so. It is the intention of the formulatkg committee to revise and update this Bulle
8、tin from time to time as may be occasioned by changes in technology, industry practice, or government regulations, or for other appropriate reasons. (From Project No. 4137, fomulated under the cognizance of the A TR-8.15 Subcommittee on Common Air Interface). Published by I”.BCOMMUNICATTONS INDUSTRY
9、 ASSOCLATION 1998 Standards and Technology Department 2500 Wilson Boulevard Arlington, VA 22201 PRICE Please refer to the current Catalog of EIA, JEDEC and TIA STANDARDS and ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada (1-SOO-854-7179) International (303-397-7956) Al
10、l rights reserved printed in U.S.A. STD-EIA TSBbS-3-ENGL 1778 W 3234b00 Ob34347 327 W TINEIAITSB69.3 TABLE OF CONTENTS 1. INTRODUCTION AND SCOPE . 1 . 1.1 REVISIONS . 1.2 REFERENCES . 1 1.3 DOCUMENT OVERV . 2 . 2. CHANNEL ACCESS 3 2.1 GENERAL DESCRIPTION 2.2 CONTROL CHANNEL ACCESS . 2.3 WORKING CHAN
11、NEL ACCESS . 3. MODULATION 4 3.1 GENERAL DESCRIPTION . 3.2 IMPLEMENTATION . 4. ADDRESING . 5 4.1 GENERAL DESCRIPTION . . 5 4.2 GROUP ID _._ . 5 4.3 LOGICAL ID . 6 . 5. TRUNKING MODES . 7 5.1 GENERAL DESCRIPTION 5.2 TRANSMISSION TRUNKING 5.3 MESSAGE TRUNKING 6. TRUNmG CONTROL CHANNEL . 9 6.1 GENERAL
12、DESCRIPTION . 9 6.2. I Inbound Control Channel Messages . . IO 6.2.2 Outbound Control Channel Description . 18 6.2.3 Outbound Control Channel Message Scheduling . . 19 6.2.4 Outbound Control Channel Messages . 19 10 6.2 TRUNKING CONTROL CHANNEL MESSAGES . 7. WORKING CHANNEL . 37 7.1 GENERAL DESCRIPT
13、ION 7.2 WORKING CHANNEL SIGNALING 7.7. I Inbound Working Channel Signaling . 37 7.2.2 Outbound Working Channel Signaling. 7.2.3 Working Channel Call Termination . APPENDIX A. GLOSSARY OF TERMS, ACRONYMS AND ABBREVIATIONS . 54 APPENDIX B. BCH AND COLOR CODING 56 APPENDIX C. CONTROL CHANNEL SCHEDULING
14、 . 59 APPENDIX D. MODIFIED WC FRAME HEADER UPDATES . 61 APPENDIX E. PREAMBLE SYNCH ACQUISITION 63 APPENDIX F. LATE ENTRY 65 APPENDIX G. MESSAGE TRUNKED CALL INTERCHANGE 67 APPENDIX H. TRANSMISSION TRUNKED CALL TERMINATION 69 i STD-EIA TSBb7.3-ENGL 1778 D 323Lib00 Ob14148 2b3 TI AIE I AITS B 69.3 APP
15、ENDIX I . MESSAGE TRUNKED CALL TERMINATION . 71 LIST OF FIGURES FIGURE I . TRANSMISSION MODEL . 2 FIGURE 2 . OUTBOUND CONTROL CHANNEL MESSAGE FORMAT 9 FIGURE 3 . INBOUND CONTROL CHANNEL MESSAGE FORMAT 9 FIGURE 4 . CONTROL CHANNEL TIMING RELATIONSHIP 1 0 FIGURE 5 . INBOUND CONTROL CHANNEL MESSAGE STR
16、UCTURE . II FIGURE 6 . NORMAL WORKING CHANNEL FRAME . 47 FIGURE 7 . INBOUND MESSAGE BCH CODE . 57 FIGURE 8 . OUTBOUND MESSAGE BCH CODE . 58 LIST OF TABLES TABLE 1 . INBOUND CONTROL CHANNEL MESSAGES . 12 TABLE 2 . OUTBOUND CONTROL CHANNEL MESSAGES 20 TABLE 3 . INBOUND WORKING CHANNEL MESSAGES 44 TABL
17、E 4 . OUTBOUND WORKING CHANNELS MESSAGES 50 II STD*EIA TSBb7-3-ENGL 1778 E 3234bOO Ob14147 LTT W Foreword (This foreword is not part of this bulletin) This Enhanced Digital Access Communications System (EDACSB) Digital Air Interface document describes the channel access, modulation, messages and for
18、mats specific to both digital trunking control channel and working channel signaling structures. All digital signaling on both the trunking control and working channels shall be at a rate of 9600 baud. This document has been developed with inputs from the Common Air Interface committee (TR-8.15), TI
19、A Industry Members, and the International EDACS Users Group. As a group, the family of EDACS documents describe the system, inclusive of the equipment requirements which allow both compatibility and interoperability between various EDACS systems and elements. The family of documents will be backward
20、 compatible and interoperable with existing installed EDACS systems as further defined within this bulletin. This bulletin is not a standard. It is being published because it is felt that there is an urgent need for technical information on the emerging digital techniques for Land Mobile Radio Servi
21、ce. PATENT ADVISORY Note: The users attention is called to the possibility that compliance with this standard may require the use of one or more inventions covered by patent rights. Users of this standard are cautioned that the following patents which are not presently available for licensing under
22、terms which are reasonable and demonstrably free from unfair discrimination, have been asserted as essential to the manufacture or use of equipment conforming to this standard. Motorola Inc. Patent Nos. US 5,104,345; US 4,716,407; US 5,239,678 By publication of this standard, no position is taken wi
23、th respect to the validity of those claims or of any patent rights in connection therewith. Except as stated above, the following patent holders so far identified, have filed statements of willingness to grant licenses under those rights on reasonable and nondiscriminatory terms and conditions to ap
24、plicants desiring to obtain such licenses. Details may be obtained from the publisher. Ericsson Inc. Patent Nos. US 4,905,302; US 4,757,536; US 4,939,746; US 5,125,102; US 5,274,837; US 5,117,501 ; US 5,574,788 TIA shall not be responsible for identhjing patents for which licenses may be required by
25、 this standard or for conducting inquiries into the legal validity or scope of those patents that are brought to its attention. STD-EIA TSBb9.3-ENGL L996 m 3234b00 ObL415L 658 m A I TI NE IA/TS B69.3 July 4, 1995 Initial Release November 7,1997 Format Changes and Revisions I .INTRODUCTION AND SCOPE
26、RF signaling within the Enhanced Digital Access Communications System (EDACS)* is discussed in this document and includes both digital trunking control channel and working channel signaling structures and message formats. The document XXX69.3-1 describes all the various signaling scenarios, indicati
27、ng how messages interact, what the resultant timing and performance is, and what decisions shall be made by both the terminal units and the system controller. The document XXX69, reference 1 , defines a system which uses this digital air interface. This document defines the modulation, coding, and m
28、essages formats for the digital air interface. Terminal unit addressing is also summarized in this document because of its direct importance and impact on signaling formats. 1 .I Revisions I REVISION I DATE I COMMENTS I I I Resulting from Task Group I I Comments 1.2References The following documents
29、 are referred to by this document. The versions and dates in these references are the latest available on the date of this document. 1 DOW&NT NUMBER .d DESCRIPTION i Enhanced Digital Access Communications System and Standards Definition Enhanced Digital Access Communications System Gatewav SDecifica
30、tion I Vocoder and ncrvption Definition I I Enhanced Digital Access Communications System I Call Procedures . EDACSO is a registered trademark of L.M. Ericsson and Ericsson Inc. I STD-EIA TSBb9-3-ENGL 1998 R 3234b00 ObLY152 794 XXX69.4 Project 16-A TIA/EIATSB69.3 Enhanced Digital Access Communicatio
31、ns System System Conformance Tests & Procedures 900 MHz Trunked Communications System Functional Requirements Development. APCO, Inc. Project 16-A. Donald D. Kavanagh I .3Document Overview The purpose of this document is to define the digital signaling process to be used for trun king control and vo
32、ice communications. Voice communication includes channel access, modulation, addressing, and working channel formats and messages, as well as error correction. Voice transmission initiates with the Voice Coder / DEcodeR (Vocoder) which converts analog voice signals to a digital data stream and vice
33、versa using advanced signal processing algorithms. A complete description is found in XXX69.2. At this point, voice signal transmissions can be encrypted. A complete description of the encryption process, before error coding has been performed, can be found in XXX69.2. The description of data transm
34、ission includes packetizing and error corrections, as described in XXX69.1. Figure 1, below, provides an illustration of the process. ENCRYPTION ERROR CODE CHANNEL I CONTROL Channel PACKETIZE ERROR CODE I Figure I. Transmission Model 2 STD-EIA TSBb7.3-ENGL 1798 m 323qb00 ObLLi153 b20 m TINE ALrSB69.
35、3 2.CHANNEL ACCESS 2.1 General Description Channel access is the process of establishing and maintaining synchronization of terminal units to RF channels. This is accomplished by a technique which allows a digital receiver to achieve time alignment with an incoming digital transmission. For the Digi
36、tal Air Interface (DAI), the method of synchronization for encoded frames of information is called Frame Synchronization. Frame Synchronization is provided by a special sequence of bits, with the location of the first bit of the message being marked. 2.2Control Channel Access The control channel acc
37、ess technique utilized is slotted ALOHA. This process is required to effectively minimize collisions between different terminal units. The basic idea of an ALOHA system is to allow terminal units to transmit whenever they have a message to send. If there are collisions, the colliding messages may be
38、 destroyed. However, the terminal unit detects if the system controller does not receive the transmission, since no acknowledge or channel grant is received. If the message was destroyed, the terminal unit waits a random amount of time and sends its message again. The waiting time must be random or
39、the same messages may collide over and over in lockstep. As stated above, the system employs an improved version of ALOHA, known as slotted-ALOHA. In a slotted-ALOHA system, a terminal unit only transmits at the beginning of a predefined slot. This reduces the probability of collisions and improves
40、the efficiency of the control channel. The system utilizes a slot 30 msec in duration. A terminal unit makes a call request by transmitting a request message in one of the inbound control channel slots, synchronized to the outbound control channel slotting. If the requesting terminal unit fails to r
41、eceive an assignment (or other administrative) message within a predetermined number of slots, it waits a random number of slot times and repeats the request. Further information on this subject can be found in Section 6. 2.3Working Channel Access Frame synchronization is performed at the beginning
42、of every voice and data message, and .it is periodically inserted every 225 msec throughout the voice message to allow terminal units to “late enter” voice messages from the middle of the transmission. 3 STD.EIA TSBb7-3-ENGL 1778 6 3234b00 Ob14154 5b7 I Bandwidth Modulation Frequency Index (h) devia
43、tion (E-fi ) TINE I AITS 669.3 Bandwidth Mask point (BT) 3. MOD U LATI0 N 3.1 General Description 25 kHz 25 kHz 12.5 kHz 12.5 kHz All digitai signaling on both the trunking control an6 working channels shall 38 at a rate of 9600 baud. This is accomplished through binary modulation of a carrier frequ
44、ency with two states via a Non-Return to Zero (NFZ) signal. A pre-modulation Gaussian filter is used between the digital input signal and the modulator stage to reduce the carrier occupied bandwidth. The modulation technique is a form of binary Frequency Shift Keying (FSK) known formally as GFSK. It
45、 is a continuous phase, binary FSK modulation with a Gaussian puise shaping function. Continuous phase means that phase continuity is maintained during the bit switching times and the FSK scheme is also known as CPFSK (Continuous Phase FSK). During digital voice transmissions on the working channels
46、, sub-audible data transmissions may take place. .625 6 kHz .77 C&G .53 5.1 kHz .53 H .49 4.7 kHz .43 J .375 3.6 kHz .38 D 3.2lmplementation The NRZ input signal is passed through a Gaussian shaping filter, The output of the filter is adjusted by 2x times the modulation index (h), then this product
47、is used to drive a voltage controlled oscillator. Systems can operate at either a 12.5 kHz or 25 kHz bandwidth. The following table summarizes the modulation parameters where the Gaussian filter is defined by its 3 dB bandwidth point : Transceiver performance specifications and methods of measuremen
48、t are covered in detail in document xxX69.4. STDmEIA TSBb9.3-ENGL 1998 m 3234b00 Ob14155 4T3 m TI AE IWS 869.3 4.ADDRESSING 4.1 General Description Addressing is the process whereby terminal units are partitioned into groups so that users with like communication specifications can communicate with e
49、ach other. Addressing shall achieve the following goals: To assure adherence to APCO-16A requirements. To specify the existence of 16,382 unit IDS, which are independent of the group field. To illustrate that there are no effective limits on the number of terminals per Subfleet. To emphasize that there is a single, unique ID for every terminal unit. APCO-16A requires that system addressing support 4 than 1600 terminal units active at any one time. Two distinct addressing fields: Group ID (1 I bits), and O0 unit addresses with no more .ogical ID (14 bits) are used. 4.2
