1、TIA/EIA TELECOMMUNICATIONS SYSTEMS BULLETIN Assignment of Access Over load Classes in the Cellular lelecommunications Services T SB 16-A (Revision of TSB 16) JUNE 2001 TELECOMMUNICATIONS INDUSTRY ASSOCIATION Tlie Telecoininiiiiicatioiis Industry Associatioii represents tlie communications sector of
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9、 or for other appropriate reasons. (From Project No. 4864, formulated under the cognizance of the TIA TR-45.1 Subcommittee on Analog Technology Published by TELECOMMUNICATIONS INDUSTRY ASSOCIATION 200 1 Standards and Technology Department 2500 Wilson Boulevard Arlington, VA 22201 PRICE: Please refe
10、r to the current Catalog of ELECTRONIC INDUSTRIES ALLIANCE STANDARDS and ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada (1-800-854-7179) International (303-397-7956) All rights reserved Printed in U. S. A. Copyright Electronic Industries Alliance Provided by IHS under
11、license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Electronic Industries Allianc
12、e Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIAIEINTSB 16-A 1. Introduction This Engineering Bulletin defines a method for the uniform use of Access Overload Classes so that roamers receive the same overload treatment as
13、home mobile stations. This bulletin also provides a definition of an Authorized Emergency Mobile Station. The actual mechanism to implement overload control may differ for analog and digital air interfaces. See the current revision of the relevant air interface standard (TIA/EIA-553, TIA/EIA-136 or
14、TIA/EIA/IS-2000) for the actual requirements and procedures beyond those described in FCC OST Bulletin 53. 2. Definitions ACCOLCp A four-bit number used to identify which overload class field controls access attempts. The “p“ indicates that this value is set in the mobile stations permanent security
15、 and identification memory. The values for ACCOLCp defined in Section 3 apply for all TIA TR-45 air interfaces. Authorized Emergency Mobile Station An Authorized Emergency Mobile Station is a Mobile Station with an ACCOLCp value of 11. Base Station A station in the Cellular Radiotelephone Service, o
16、ther than a mobile station, used for radio communications with mobile stations. Load Shedding The act of denying Mobile Stations access to a Base Station, typically for the purpose of preventing more traffic from being presented to the Base Station than it can process. Mobile Station A station in th
17、e Cellular Radiotelephone Service intended to be used while in motion or during halts at unspecified points. It is assumed that mobile stations include portable units (e.g., hand- held personal units) as well as units installed in vehicles. Overload Control Global Action Message A single word global
18、 action message containing sixteen overload class fields (OLC N, N = O to 15). i Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIAIEIAITSB 16-A 151413 1211109876543210 3. Use of Overlo
19、ad Control Classes The cellular protocol adopted by the FCC (see OST Bulletin 53) provides a means of load shedding when a system is overloaded, by denying access requests for service. Each mobile station is assigned one of 16 slots, or number designations, called ACCOLCp (see OST Bulletin 53 Sectio
20、n 2.3.5, pgs. 2-7). A system may transmit an Overload Control Global Action Message, (see OST Bulletin 53 Section 3.7.1.2.2, pgs. 3-17), in which each of the 16 slots can be marked 1” or O”. A mobile station must examine this message (see OST Bulletin 53 Section 2.6.3.4, pgs. 2- 16), and may attempt
21、 access if its slot is marked “1”. In order for the overload control capabilities to remain useful in systems that are providing services to roamers, industry-wide uniformity in the assignment of the overload control bits is necessary. The following assignments are proposed: Bits O through 9 will be
22、 used for the uniform distribution of assignments to Mobile Stations. One possible method for assigning the bits in a uniform manner is to make the bit correspond to the decimal value of the least significant digit in the mobile terminals directory number. Bit 10 will be used for the system test pur
23、poses Bit 11 will be used for Authorized Emergency Mobile Stations. Bits 12 through 15 will remain unused and reserved for future assignment. Thus, the normal subscriber traffic on the system can be divided into ten (10) relatively equal pools. Traffic offered could then be controlled in 10% increme
24、nts which should prove to be a fine enough control to affect overload conditions without creating system oscillation. All existing Mobile Stations with overload control bits already assigned will be “grandfathered“ into the system until they are brought in for another service reason. Authorized Emer
25、gency Mobile Stations are typically defined as: Any Mobile Station operated by a federal, state, provincial, county, or municipal law enforcement agency, used by sworn police officers in Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for ResaleNo reproduction or n
26、etworking permitted without license from IHS-,-,-TIAIEIAITSB 16-A fulfillment of the law enforcement mission of the agency as defined within its charter. Any Mobile Station operated by a federal, state, provincial, county, or municipal fire department or incorporated fire district, used by members o
27、f the department (or district) in fulfillment of the fire prevention and/or fire fighting mission as defined within its charter. Any Mobile Station operated by a federal, state, provincial, county, or municipal agency used by that agency in the provision of emergency medical services and/or rescue s
28、ervices authorized by the charter of the agency. 3 Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for
29、ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Electronic Industries Alliance Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
