Abis interface Technical Specification for cdma2000 Spread Spectrum Systems. (A.S0003 : BSC to BTS Interoperability specification (Abis))

Transcription

1 GPP A.S000 Version Date: March 1, 000 Abis interface Technical Specification for cdma000 Spread Spectrum Systems (A.S000 : BSC to BTS Interoperability specification (Abis)) COPYRIGHT GPP and its Organizational Partners claim copyright in this document and individual Organizational Partners may copyright and issue documents or standards publications in individual Organizational Partner's name based on this document. Requests for reproduction of this document should be directed to the GPP Secretariat at secretariat@gpp.org. Requests to reproduce individual Organizational Partner's documents should be directed to that Organizational Partner. See for more information.

2 Revision History Revision Description Date Rev Initial Publication March 000

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4 INTRODUCTION.... OBJECTIVES....1 SCOPE OF THE DOCUMENT.... GLOSSARY....1 GLOSSARY.... NETWORK REFERENCE MODEL AND INTERFACES....1 SUPPORT OF USER TRAFFIC CONNECTIONS TO A FRAME SELECTOR FUNCT ION.... SUPPORT OF PAGING CHANNEL MESSAGING.... SUPPORT OF ACCESS CHANNEL MESSAGING.... SUPPORT OF RADIO FUNCTIONS.... SUPPORT OF BROADCAST SYSTEM INFORMATION FUNCTIONS.... LAYERS 1 & Physical Layer Specification (Layer 1) Use of ATM (Layer ) Field of Application ATM Layer ATM Adaptation Layer Network and Transport Protocols Signaling Connection Transport Protocol Options User Traffic Connection Transport Protocol Options TCP Transport Protocol Usage General Use of TCP Use of TCP for the Abis Interface IP Network Protocol Usage...1. CALL PROCESSING MOBILE ORIGINATING CALL...1. MOBILE TERMINATED CALL.... CALL CLEARING Call Clearing initiated by MS..... Call Clearing initiated by BS/MSC..... Call Clearing initiated by BTS...0. HANDOFF Soft/Softer Handoff (Intra-BTS)..... Soft/Softer Handoff (Inter-BTS).... SMS DELIVERY SMS Delivery on the Paging channel..... SMS Delivery on the Access channel..... SMS Delivery on the Traffic channel to MS..... SMS Delivery on the Traffic channel from MS... 1

5 TRAFFIC BURST OPERATION Initial Traffic Burst Example Abis Connection Not Yet Established..... Subsequent Traffic Burst Example.... ABIS INTERFACE MESSAGE FORMATS....1 ABIS INTERFACE MESSAGE Abis-ACH Msg Transfer Abis-ACH Msg Transfer Ack Abis-PCH Msg Transfer Abis-PCH Msg Transfer Ack Abis-BTS Setup Abis-BTS Setup Ack Abis-BTS Release Abis-BTS Release Ack Abis-Burst Request Abis-Burst Response Abis-Burst Commit Abis-Connect Abis-Connect Ack Abis-Remove Abis-Remove Ack Abis-IS-000 FCH Fwd Abis-IS-000 FCH Rvs Abis-Traffic Channel Status Abis-BTS Release Request Abis-IS-000 SCH Fwd Abis-IS-000 SCH Rvs Abis-IS-000 DCCH Fwd Abis-IS-000 DCCH Rvs.... INFORMATION ELEMENT DEFINITIONS....1 INFORMATION ELEMENT IDENTIFIERS.... MESSAGE TYPE.... CORRELATION ID.... MOBILE IDENTITY.... CELL IDENTIFIER.... AIR INTERFACE MESSAGE.... MANUFACTURER S SPECIFIC RECORDS.... LAYER A CK REQUEST /RESULTS.... CAUSE.... CALL CONNECTION REFERENCE.... BAND CLASS....1 PRIVACY INFO...

6 CELL IDENTIFIER LIST....1 SDU-ID....1 PHYSICAL CHANNEL INFO....1 ABIS CELL INFO....1 SERVICE OPTION....1 PACA TIMESTAMP....1 QUALITY OF SERVICE PARAMETERS ABIS CONNECT INFORMATION ABIS FROM ID...0. ABIS TO ID...0. DOWNLINK RADIO ENVIROMENT...1. CDMA SERVING ONE WAY DELAY...1. FORWARD BURST RADIO INFO...1. REVERSE BURST RADIO INFO...1. IS-000 FORWARD POWER CONTROL MODE...1. IS-000 FPC GAIN RATIO INFO.... CELL IDENTIFIER LIST...

7 Introduction. Objectives This document specifies the Abis (between the BSC and the BTS) interface for cdma000 system. Abis interface is the reference point between the BSC and the BTS. The signaling flows and these signals are described. The Abis interface specification achieves providing an open and interoperable system. And Abis interface does not disturb the coexistence with other A sub-interfaces specified in GPP A.S Scope of the document. Glossary.1 Glossary This specification defines the interface between BTS and BSC within the BS. The interface between BSs is specified in the GPP A.S0001 GPP Access Network Interfaces Interoperability Specification (January 1 th, 000). The OAM&P related information can be transferred on this interface and the transport layer for these information are desirable to match with Abis interface. They are for further study and this specification does not contain them.. The following is a list of acronyms that are used in this specification. G-IOS Third Generation InterOperability Specification AWIM Alert With Information Message BS Base Station BSC Base Station Controller BTS Base Tranceiver System ECAM Enhanced Channel Assignment Message GPM General Page Message ITU International Telecommunications Union MAC Medium Access Control MS Mobile Station MSC Mobile Switching Center ORM Origination Message

8 PRM QoS RAN RN RRC SCCM SCM SDU Page Response Message Quality of Service Radio Access Network Radio Network Radio Resource Control Function Service Connect Completion Message Service Connect Message Selection/Distribution Unit function

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10 . Network Reference Model and Interfaces Following figure shows the network reference model used by this specification.

11 B S BSC SDU Function Abis Signaling Abis Signaling Abis Interface Abis Traffic Abis Traffic BTS CH element BTS CH element a) Abis interface = Abis signaling + Abis traffic b) An SDU function is located in a BSC c) A channel element is located in a BTS Notes : The handoff procedure between BTSs within a BSC is defined in this document. The handoff procedures between the BSs have already defined in GPP A.S0001. Fig.-1. Network Reference Model for Abis interface \\\\\\\\

12 Air Interface Abis Interface BS MS BTS Abis traffic BSC FCH (f/r-dsch, f/r-dtch) SCH (f/r-dtch) DCCH (f/r-dsch, f/r-dtch) FCH (Abis-IS-000 FCH Fwd/Rvs) SCH (Abis-IS-000 SCH Fwd/Rvs) DCCH (Abis-IS-000 DCCH Fwd/Rvs) Abis Signaling ACH (r-csch) PCH (f-csch) ACH (Abis-ACH Msg Transfer) PCH (Abis-PCH Msg Transfer) BS Control Signaling OAM Signaling (FFS) 1 Note: This figure is informative. All signals defined in air interface are not described in this Figure. Figure -. Relationship between Air interface and Abis interface (Intra BS Model)

13 Table -1 Abis interface description Abis function Transaction Abis Message (A/A message related to Abis ) Abis connection - call setup - Abis -BTS Setup (A-HO Req) establish - Handoff - Abis -BTS Setup Ack (A-HO Req Ack) (BSC invoke) - Abis -Connect (A-Connect) Abis connection release (BSC invoke) Abis connection release (BTS invoke) PCH transfer ACH transfer SCH transfer and establish - call release - Handoff - Abis -Connect Ack - Abis -BTS Release - Abis-BTS Release Ack - Abis -Remove - Abis -Remove Ack - Abis -BTS Release Request - Abis -BTS Release - Abis-BTS Release Ack - Abis -Remove - Abis -Remove Ack - Abis -PCH Msg Transfer - Abis -PCH Msg Transfer Ack - Abis -ACH Msg Transfer - Abis -ACH Msg Transfer Ack - SCH setup - Abis-Burst Request - Abis-Burst Response -Abis-Burst Commit (A-Connect Ack) (A-Drop) (A-Drop Ack) (A-Remove) (A-Remove Ack) (A-Tgt rm. req.) (A-Drop) (A-Drop Ack) (A-Remove) (A-Remove Ack) (A-PCH...) (A-PCH... Ack) (A-ACH...) (A-ACH... Ack) (A-Burst Req.) (A-Burst Rsp.) (A-Burst Commit) Support of user traffic connections to a frame selector function In a CDMA system, the user traffic (voice, data, etc.) of a Mobile Station may be connected to the network using one or more connections from MS to BTS(s). If multiple connections are used for a single flow of user information, the user traffic connection is s aid to be in soft handoff. The first step within the network is to carry these multiple connections back to a single point from which a selection is made of the best frame received over the radio connections. This implies a connection from each involved BTS back to a central point where frame selection occurs. This central point is referred to as the SDU function Support of paging channel messaging When a BS sends a message on a paging channel, the BSC typically formats the majority of the message and then forwards it to the BTS along with various parameters including the destined cell identifier The ability to forward such a paging message from the BSC to the BTS is part of the functionality of the Abis interface. An additional requirement of a CDMA system is that such messages may also need to be forwarded between BSCs to be transmitted to a BTS belonging to a BSC other than the BSC that originally created the message. This requirement comes through support for access handoff and other such cdmaone and cdma000 features. The BSC to BSC

14 signaling on the A interface to support such forwarding has been defined in the G-IOS specification.. Support of Access channel messaging When an MS sends a message on an access channel, the BTS will forward that message to the BSC along with various parameters including the identity of the cell and sector on which the message was received, etc. The ability to forward such an access message from BTS to the BSC is part of the functionality of the Abis interface. An additional requirement of a CDMA system is that such a message may also need to be forwarded between BSCs (i.e., to a BSC other than the one which owns the BTS that originally received the message). This requirement comes through support for access handoff and other such cdmaone and cdma000 features. The BSC to BSC signaling on the A interface to support such forwarding has been defined in the G-IOS specification.. Support of radio functions Various functions can be considered with respect to the radios that exist under the control of a BTS. The interaction of these functions with Operations, Administration, Maintenance, and Provisioning (OAM&P) are for further study.. Support of broadcast system information functions In a cdmaone or a cdma000 system, each BTS must broadcast various pieces of system information that the MS will capture and use during its interactions with the network. Much of that system information may be administrated through OAM&P functions. A small amount of such system information may be placed in BTS and OAM&P control of a BTS for the same purposes must be defined.. Layers 1 & Physical Layer Specification (Layer 1) The Abis interface is based on the use of: T1 digital transmission system interfaces. Each 1. Mbits/s interface

15 provides* kbits/s or * kbits/s channels which can be used for traffic or signaling as the operator requires. Common physical interface standards are found in ANSI T1.1 and related references. E1 digital transmission interfaces consisting of 0* kbits/s user channels can also be used for traffic or signaling as the operator requires, and as applicable to the network. As a BS/MSC agreed option, dedicated DS0 signaling link[s] may be used instead of the T1/E1 interface. T digital transmission interfaces supporting transmission rates of. Mbits/sec. OC digital transmission interfaces supporting transmission rates of 1. Mbits/sec... Use of ATM (Layer ) Asynchronous Transfer Mode (ATM) is a suite of protocols that allow fast, efficient delivery of user traffic in a packet environment. ATM, for the purposes of this standard, consists of two main layers: the ATM Layer that uses the physical layer, and the ATM Adaptation Layer that adapts the basic ATM layer to specific uses... Field of Application.. ATM Layer Asynchronous Transfer Mode (ATM) is used to transport both signaling and user traffic (voice/data). The ATM Layer uses a basic octet cell consisting of a octet header and octet payload. This standard uses the ATM Layer as specified in ANSI T1.-1 Telecommunications Broadband ISDN - ATM Layer Functionality and Specification without modification. For this specification only ATM permanent virtual circuits (PVC s) shall be required for the Abis interface. These virtual circuits shall be configured through administrative procedures and no special signaling interface procedures, e.g., ATM UNI (Q.1), shall be required... ATM Adaptation Layer To make use of the basic cell transfer capability of the ATM Transport Layer in specific uses, various ATM Adaptation Layers (AALs) have been defined. Within this standard, two AALs are used: AAL 1 - for the transfer of signaling, and AAL - for the transfer of user traffic (voice/data) on A traffic subchannels. 1 AAL is described in ITU-T I.., B-ISDN ATM Adaptation Layer Specification: Type AAL, August 1. 1

16 Both AAL and AAL will be used without modification in this standard. The Service Specific Segmentation and Reassembly (SSSAR) sublayer for AAL, as specified in ITU-T I..1, is used for segmentation and reassembly of AAL SDUs. In this version of this standard, the functionality of other sublayers of AAL is not supported. Specifically, Service Specific Transmission Error Detection (SSTED) and Service Specific Assured Data Transfer (SSADT) are not included. AAL is described in ITU-T Recommendation I.., B-ISDN ATM Adaptation Layer Type Specification, September 1. 1

17 1 1.. Network and Transport Protocols...1 Signaling Connection Transport Protocol Options Signaling over the Abis interface requires a reliable transport protocol and appropriate addressing and routing mechanisms to deliver messages from source to destination. The Abis signaling application is independent of the underlying transport, which is left to the discretion of operators and manufacturers. The signaling protocol stack options available to operators and manufacturers for the Abis interface include: Abis Interface (signaling connection): Abis Signaling Application TCP/IP AAL ATM Phys. Lyr

18 User Traffic Connection Transport Protocol Options The protocol stack options for transport of user traffic that are available to operators and manufacturers include: Abis Interface (user traffic subchannel): Abis Traffic SSSAR AAL ATM Phys. Layer... TCP Transport Protocol Usage The standard TCP protocol, as described in reference, IOS section 1.., shall be used for establishing, using, and clearing TCP connections.... General Use of TCP TCP connections for signaling may be set up on a per-call basis or signaling messages for multiple calls may be multiplexed on a single TCP connection. The TCP protocol provides a reliable byte stream transfer. Therefore, a means needs to be provided for two application entities to delimit the messages sent between them. The technique for such delimitation is given below....1 Message Delimiting in TCP TCP provides a reliable byte stream between two application entities. Because the protocol in this standard uses messages to communicate, these messages shall be delimited in the TCP byte stream. Such delimitation shall be done by means of a two byte flag field and a two byte length field inserted at the beginning of each message sent over a TCP connection. The flag field shall contain the hex value F. The purpose of the flag field is to facilitate verification of message boundaries, and fast reestablishment of synchronization if synchronization of message boundaries is lost. See Figure - below. 1

19 1 0 Flag Flag Length Length Msg (MSB ) First Octet of Abis Application Message Second Octet of Abis Application Message Third Octet of Abis Application Message... Last Octet of Abis Application Message Flag Flag Length Length Msg (MSB ) First Octet of Abis Application Message Second Octet of Abis Application Message Third Octet of Abis Application Message... Last Octet of Abis Application Message Flag Flag Length Length Msg (MSB ) First Octet of Abis Application Message Second Octet of Abis Application Message Third Octet of Abis Application Message... (LSB) (LSB) (LSB) Figure -- Delimiting Messages in an Abis Application TCP Byte Stream 1

20 TCP Connection Establishment A new TCP connection is established when a signaling message related to a call has to be exchanged over an interface, and no such connection exists over the particular interface. Normal TCP connection establishment procedures are used.... TCP Connection Release An existing TCP connection over an interface is released when there are no more signaling messages to be exchanged over the interface. Normal TCP connection release procedures are used.... TCP Port Usage The following TCP port values are reserved for signaling across Abis interfaces: Abis : 0 -- This is the well-known TCP port at a BS used for Abis signaling interconnection between BTSs and a BSC. Editor s Note : These port number is requested now. The value may be changed. And the value will be defined in A.S0001 later version. A: (BS-to-BS) 0 -- This is the well-known TCP port at a BS used for signaling interconnection to another BS. A: (BS-to-PCF) 0 -- This is the well-known TCP/UDP port at a BS used for signaling interconnection to a PCF.... Use of TCP for the Abis Interface The standard "Transport Control Protocol (TCP)", as described in RFC and shown in IOS section..1 shall be used on the A (signaling subchannel) and A interfaces... IP Network Protocol Usage The standard IP protocol, as defined in RFC 1 (see IOS section 1..), shall be used for routing Internet Protocol packets. 1

21 . Call Processing 1

22 Mobile Originating Call This section describes the call flow associated with a mobile station call origination in the cdma000 system. MS BTS BSC MSC Origination Null Traffic Extended Channel Assignment Service Connect BS Service Connect Completion Abis-Connect Abis-Connect Ack Abis-BTS Setup Ack Abis-IS-000 FCH Fwd (Null Data) Abis-IS-000 FCH Rvs (Idle) Traffic Channel Preamble Abis-IS-000 FCH Rvs (T-CH Preamble) BS Ack Order Idle Tch Data Frames MS Ack Order Abis-ACH Msg. Transfer (ORM) Abis-BTS Setup Abis-PCH Msg. Transfer (ECAM) Abis-IS-000 FCH Fwd (BS Ack Order) Abis-IS-000 FCH Rvs (Idle) Abis-IS-000 FCH Rvs (MS Ack Order) Abis-IS-000 FCH Fwd (SCM) Abis-IS-000 FCH Rvs (SCCM) Fig. -1 Mobile Originating Call Complete L Info: CM Service Req. T0 Assignment Complete Assignment Request T Time Comment a b c d e f g h i j k l m n o p q 1

23 a. The MS transmits an Origination Message, with layer acknowledgement required, over the access channel of the air interface to the BTS. Then the BTS sends an Abis -ACH Msg Transfer including the Origination message frame in Abis signaling interface. b. The BSC constructs the CM Service Request message, places it in the Complete Layer Information message, sends the message to the MSC, and starts timer T0. The BSC may request the MSC to allocate a preferred terrestrial circuit. c. The MSC sends an Assignment Request message to the BSC to request assignment of radio resources. This message will include information on the terrestrial circuit, if one is to be used between the MSC and the BSC. The MSC then starts timer T. d. The BSC sends Abis -BTS Setup message to get the resource between BSC and BTS. The BSC shall allocate a code channel and include it in the Abis -BTS Setup. e. If resources are available, BTS responses with Abis -Connect message. f. The BSC sends Abis -Connect Ack message to the BTS. g. The BTS sends Abis -BTS Setup Ack to the BSC to acknowledge the Abis -BTS Setup. The BTS may allocate a code channel. In this case, the BTS includes the allocated code channel in Abis -BTS Setup Ack. Unless the BTS allocates a code channel, the BTS includes the code channel that has been indicated by Abis -BTS Setup (step d) in the Abis -BTS Setup Ack. h. The BSC transmits the Abis -IS-000 FCH Fwd message to the BTS including Null Data to let the BTS send Null traffic data toward the MS. Then the BTS begin sending Null Traffic data for synchronizing between the BTS and the MS. The BTS may have function which sends Null Traffic data for synchronization between the BTS and the MS. Whether the BTS has the function or not, the BSC is assumed to send Null Traffic. i. The BTS sends Abis -IS-000 FCH Rvs message to the BSC including Idle data. j. The BSC sends an Abis -PCH Msg Transfer including Extended Channel Assignment message to the BTS. The BTS sends an Extended Channel Assignment message to the MS over the paging channel of the radio interface (with the MS address) to initiate the establishment of a radio traffic channel. k. The MS begins sending the traffic channel preamble (TCH Preamble) over the designated reverse traffic channel. Then the BTS transmits this preamble with an Abis -IS-000 FCH Rvs message. l. Once the BSC acquires the reverse traffic channel, it sends an Abis -IS-000 FCH Fwd message including a Base Station Acknowledgement Order with layer acknowledgement required, to the MS over the forward traffic channel. m. After receiving a BS Ack Order message, the MS begins sending Idle Tch Data Frames over the reverse traffic channel. Then the BTS transmits this frame message with an Abis -IS-000 FCH Rvs message. n. The MS Ack Order message is sent from MS, and then the BTS transmits it to the BSC with an Abis -IS-000 FCH Rvs message. o. The BSC then sends the Abis -IS-000 FCH Fwd message including the Service Connect message to the BTS specifying the service configuration for the call. Then the BTS transmits the Service Connect message to the MS. The MS begins processing traffic in accordance with the specified service configuration. 0

24 p. On receipt of the Service Connect message, the MS responds with a Service Connect Completion message. Then the BTS transmits it with an Abis -IS-000 FCH Rvs message. q. After the radio traffic channel and circuit have both been established and fully interconnected, the BSC sends the Assignment Complete message to the MSC and considers the call to be in conversation state. The MSC stops timer T upon receipt of the Assignment Complete message. 1

25 . Mobile Terminated Call This section describes the call flow associated with a mobile station call termination in the cdma000 system. An Abis -PCH Msg Transfer Ack and an Abis -ACH Msg Transfer Ack are not presented in the following figure to simplify the figure, but actually, they would be sent after receipt of Abis -PCH Msg Transfer message or Abis -ACH Msg Transfer message respectively. MS BTS BSC MSC Time Comment General Page Page BS Ack Order Extended Channel Null Traffic TCH Preamble BS Ack Order Idle Tch Data MS Ack Service Connect AbAbis -PCH Msg. Transfer (GPM) Paging Request AbAbis -ACH Msg. Transfer Complete L Info: Paging Response AbAbis -PCH Msg. Transfer (BS Ack) AbAbis -BTS Setup AAbis -Connect AAbis-Connect Ack AbAbis -BTS Setup Ack AAbis -IS-000 FCH Fwd (Null Data) AAbis -IS-000 FCH Rvs (Idle) AbAbis-PCH Msg. Transfer (ECAM) AAbis-IS-000 FCH Rvs (Preamble) AAbis -IS-000 FCH Fwd (BS Ack) AAbis -IS-000 FCH Rvs (Idle) AAbis -IS-000 FCH Rvs (MS Ack) AAbis -IS-000 FCH Fwd (SCM) Assignment Serv. Con. Completion AAbis -IS-000 FCH Rvs (SCCM) Assignment Alert with Info AAbis-IS-000 FCH Fwd (AWIM) MS Ack Order Connect Order BS Ack Order AAbis-IS-000 FCH Rvs (MS Ack) AAbis -IS-000 FCH Rvs (Connect Order) AAbis -IS-000 FCH Fwd (BS Ack) Connect Fig. - Mobile Terminated Call a b c d e f g h i j k l m n o p q r s t u v w x y

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27 a. The MSC sends the Paging Request message to the BSC to initiate a mobile terminated call setup scenario. b. The BSC constructs a General Page Message (GPM), put the message into an Abis -PCH Msg Transfer Message and sends the Abis -PCH Msg Transfer Message to the BTS. The BTS sends the GPM to the MS over the paging channel. The BSC may send this message to multiple BTSs managed by this BSC. In the following description, it is assumed that the BSC sends this message to single BTS. c. The MS acknowledges the page by transmitting a Page Response Message (PRM) to the BTS over the access channel. Upon receipt of this message, the BTS put this message into an Abis -ACH Msg Transfer Message and sends it to the BSC. d. The BSC sends the Complete Layer Information message containing the Paging Response message to the MSC. e. The BSC acknowledges the receipt of the PRM from the MS with a Base Station Acknowledgment Order to the MS. This message is sent by the BSC to the BTS in the Abis -PCH Msg Transfer. f. The MSC sends an Assignment Request message to request assignment of radio resources. g. The BSC sends an Abis -BTS Setup message to the BTS to request allocation of radio resources at the BTS. The BSC shall allocate a code channel and include it in the Abis -BTS Setup. h. Upon receipt of Abis -BTS Setup message, the BTS allocates radio resources and sends an Abis -Connect message to initiates an Abis connection and to report the result of resource allocation. i. The BSC replies with an Abis -Connect Ack message to complete the Abis connection. j. The BTS sends Abis -BTS Setup Ack to acknowledge the Abis -BTS Setup. The BTS may allocate a code channel. In this case, the BTS includes the allocated code channel in the Abis -BTS Setup Ack. Unless the BTS allocates a code channel, the BTS includes the code channel that has been indicated by Abis -BTS Setup (step g) in the Abis -BTS Setup Ack.

28 k. The BSC sends an Abis -IS-000 FCH Fwd (Null Traffic Data) message to the BTS. The BTS starts sending Null Traffic Data to the MS. This allows the MS to acquire the FCH (Fundamental channel). The BTS may have function which sends Null Traffic data for synchronization between the BTS and the MS. Whether the BTS has the function or not, the BSC is assumed to send Null Traffic. l. Upon receiving the first Abis -IS-000 FCH Fwd (Null Traffic Data) message, the BTS starts to send Abis -IS-000 FCH Rvs (Idle frame) message to the BSC. m. The BSC sends an Extended Channel Assignment message to assign the FCH. n. The MS starts to send the Traffic Channel Preamble. Upon receiving the Traffic Channel Preamble, the BTS stops sending the idle frames and starts sending the traffic frames containing the Traffic Channel Preamble. o. The BSC sends the BS Ack Order to the MS via the BTS in the Abis -IS-000 FCH Fwd message. p. The MS stops transmitting the Traffic Channel Preamble and starts to transmit idle traffic channel data frames upon receipt of the BS Ack order. q. The MS sends the MS Ack Order to acknowledge the BS Ack order. This is sent by the BTS to the BSC in the Abis -IS-000 FCH Rvs message. r. The BSC sends the Service Connect Message (SCM) to the MS specifying the service configuration for the call. This message is sent by the BSC to the BTS in the Abis -IS-000 FCH Fwd message. The MS begins processing traffic in accordance with the specified service configuration. s. On receipt of the Service Connect Message (SCM), the MS responds with a Service Connect Completion Message (SCCM). Upon receipt of this message at the BTS, it sends Abis -IS-000 FCH Rvs message containing this message to the BSC. t. After the radio traffic channel and circuit have both been established, the BSC sends the Assignment Complete message to the MSC.

29 u. The BSC sends an Alert with Information Message (AWIM) to the MS to cause ringing at MS. This message is sent by the BSC to BTS in the Abis -IS-000 FCH Fwd message. v. The MS acknowledges the reception of the Alert with Information Message by transmitting the MS Ack Order. w. When the call is answered at the MS, a Connect Order, with acknowledgment required, is transmitted to the BSC via the BTS. x. The BSC acknowledges the Connect Order with the BS Ack order. y. The BSC sends a Connect message to the MSC to indicate that the call has been answered at the MS. At this point, the call is considered stable and in the conversation state. 1 1

30 . Call Clearing Call Clearing initiated by MS BS MS BTS BSC MSC Release Order Abis-IS-000 FCH Rvs (Release Order) Clear Request T00 Clear Command Abis-IS-000 FCH Fwd (Release Order) Release Order ) Abis-BTS Release Abis-Remove T1 Abis-Remove Ack Abis-BTS Release Ack Clear Complete Time a b c d e f g h i Fig. - Call Clearing initiated by MS 0 1 a. The MS initiates call clearing by transmitting a Release Order over the reverse traffic channel. In response to the order, BTS sends an Abis -IS-000 FCH Rvs message containing the Release Order message to the BSC. b. The BSC then sends the Clear Request message to the MSC to initiate the call clear transaction. Timer T00 is started by the BSC. c. The MSC starts timer T1 and sends a Clear Command message to the BSC to instruct the BSC to release the associated dedicated resource (such as terrestrial circuit). The BSC stops timer T00. d. In response to the Clear Command message from the MSC, the BSC sends an Abis -IS-000 FCH Fwd message containing the Release

31 1 1 Order message. The BTS then acknowledges the MS by sending it a Release Order over the forward traffic channel. e. The BSC then sends an Abis -BTS Release message to the BTS. f. The BTS releases the radio resource and sends Abis -Remove message to the BSC. g. In response to the Abis -Remove message from the BTS, BSC sends an Abis -Remove Ack message to the BTS. h. The BTS sends an Abis -BTS Release Ack message to the BSC to acknowledge the Abis removal. i. The BSC sends a Clear Complete message to the MSC. Then BSC releases the related terrestrial circuit to the BTS, if allocated. And the MSC stops timer T1 upon receipt of the Clear Complete message. The MSC releases the underlying transport connection. 1 1

32 .. Call Clearing initiated by BS/MSC BS MS BTS BSC MSC Time Release Order Abis-IS-000 FCH Fwd (Release Order) Clear Request T00 Clear Command a b c Release Order Abis-IS-000 FCH Rvs (Release Order) Abis-BTS Release T1 d e Abis-Remove f Abis-Remove Ack Abis-BTS Release Ack Clear Complete g i 1 Fig. - Call Clearing initiated by BS/MSC a. In the case where the BSC detects some failures related the call, the BSC sends a Clear Request message to the MSC. The BSC starts timer T00 and waits for the Clear Command from the MSC (step b). A Call Clearing flow initiated by BSC starts from this step. b. The MSC starts timer T1 and sends a Clear Command message to instruct the BSC to release the associated dedicated resource (such as terrestrial circuit). In the case of a Call Clearing initiated BS, the BSC stops timer T00. A Call Clearing flow initiated by MSC starts from this step. c. In response to the Clear Command message from the MSC, the BSC sends Abis -IS-000 FCH Fwd containing the Release Order message. The BTS sends the Release Order message to the MS over the forward traffic channel. d. The MS replies with a Release Order over the reverse traffic channel. In response to the order, BTS sends an Abis -IS-000 FCH Reverse containing the Release Order message to the BSC.

33 1 e. The BSC then sends an Abis -BTS Release message to the BTS. f. The BTS releases the radio resource and sends Abis Remove message to the BSC. g. In response to the Abis Remove message from the BTS and BSC sends an Abis Remove Ack message to the BTS. Then BSC releases the related terrestrial circuit to the BTS, if allocated. h. The BS sends an Abis -BTS Release Ack message to the BSC to acknowledge the Abis removal i. Upon receipt of the Abis BTS Release Ack message, the BSC sends the Clear Complete message to the MSC. The MSC stops timer T1 upon receipt of the Clear Complete message. The MSC releases the underlying transport connection. 1.. Call Clearing initiated by BTS BS MS BTS BSC MSC Time Abis-BTS Release Request Clear Request a Release Order Abis-IS-000 FCH Fwd (Release Order) T00 Clear Command b c Release Order Abis-IS-000 FCH Rvs (Release Order) ) Abis-BTS Release T1 d e Abis-Remove f Abis-Remove Ack g Abis-BTS Release ACK Clear Complete i 1 1 Fig. - Call Clearing initiated by BTS 1 1 a. In the case of a radio channel failure between the MS and the BTS, or if the MS is not active, the BTS sends an Abis -BTS Release Request 0

34 message to BSC. In response to the message the BSC sends a Clear Request message to the MSC. The BSC starts timer T00 and waits for the Clear Command from the MSC (step b). A Call Clearing flow initiated by BS starts from this step. b. The MSC starts timer T1 and sends a Clear Command message to instruct the BSC to release the associated dedicated resource (such as terrestrial circuit). The BSC stops timer T00. c. In response to the Clear Command message from the MSC, the BSC sends Abis -IS-000 FCH Fwd containing the Release Order message.the BTS sends the Release Order over the forward traffic channel. d. The MS replies with a Release Order over the reverse traffic channel. In response to the order, BTS sends an Abis -IS-000 FCH Rvs containing the Release Order message to the BSC. e. The BSC then sends an Abis -BTS Release message to the BTS. f. The BTS releases the radio resource and sends Abis -Remove message to the BSC. g. In response to the Abis -Remove message from the BTS and BSC sends an Abis Remove Ack message to the BTS and returns a Clear Complete message to the MSC. Then BSC releases the related terrestrial circuit to the BTS, if allocated. h. The BS sends an Abis -BTS Release Ack message to the BSC to acknowledge the Abis -removal i. Upon receipt of the Abis BTS Release Ack message, the BSC sends the Clear Complete message to the MSC. The MSC stops timer T1 upon receipt of the Clear Complete message. The MSC releases the underlying transport connection. 1

35 . Handoff This section describes handoff procedure using Abis interface within the BS. The handoff between BSs is realized by A and A interface specified in GPP A.S Soft/Softer Handoff (Intra-BTS) MS BTS BSC Time Ab Abis-BTS Setup A Abis -Connect A Abis -Connect Ack Ab Abis -BTS Setup Ack a b c d Extended/General/Universal Handoff Direction Message A Abis -IS-000 FCH Fwd e MS Ack Order AAbis-IS-000 FCH Rvs f Handoff Completion Message AAbis-IS-000 FCH Rvs g BS Ack Order AAbis -IS-000 FCH Fwd h Fig.- Soft/Softer Handoff (Intra-BTS) a. The BSC sends an Abis -BTS Setup message to the BTS to request that the specified cells be added to the call. The BSC shall allocate a code channel and include it in the Abis -BTS Setup. b. The BTS allocates internal resources related to the specified cells. The BTS sends an Abis -Connect message to the SDU function. c. The SDU function of BSC replies with an Abis -Connect Ack message and allocate internal resources. d. The BTS sends Abis -BTS Setup Ack to acknowledge the Abis -BTS Setup. The BTS may allocate a code channel. In this case, the BTS includes the allocated code channel in Abis -BTS Setup Ack. Unless the BTS allocates a code channel, the BTS includes the code channel that has been indicated by Abis -BTS Setup (step a) in the Abis -BTS Setup Ack. e. The BSC sends an Extended / General / Universal Handoff Direction Message to the MS to add the new cell to the active set.

36 f. The MS acknowledges receipt of the Extended / General / Universal Handoff Direction Message with an MS Ack Order. g. The MS indicates successful results of processing the Extended / General / Universal Handoff Direction Message by sending a Handoff Completion message. h. The BSC acknowledges receipt of the Handoff Completion Message by sending a BS Ack Order... Soft/Softer Handoff (Inter-BTS) MS Source BTS Target BTS BSC Time Forward Frames Extended/General/Universal Handoff Direction Message AbAbis-BTS Setup A Abis -Connect A Abis -Connect Ack AbAbis -BTS Setup Ack A Abis -IS-000 FCH Fwd( Forward Frames) AAbis-IS-000 FCH Rvs( Idele Frames) AbAbis-Traffic Channel AAbis-IS-000 FCH Fwd a b c d e f g h i MS Ack Order AAbis -IS-000 FCH Rvs j Handoff Completion Message AAbis -IS-000 FCH Rvs k BS Ack Order A Abis-IS-000 FCH Fwd l Fig.- Soft/Softer Handoff (Inter-BTS) a. The BSC decides that one or more cells at the target BTS are needed to support the call in soft/softer handoff. The BSC sends an Abis -BTS Setup to the target BTS to get the resource between BSC and the target BTS. The BSC shall allocate a code channel and include it in the Abis -BTS Setup. b. If resources are available, The target BTS responses with Abis -Connect message. c. The BSC replies with an Abis -Connect Ack message to complete the Abis connection. d. The target BTS sends Abis-BTS Setup Ack to acknowledge the Abis -BTS Setup. The target BTS may allocate a code channel. In this case, the target BTS includes the allocated code channel in Abis -BTS Setup Ack. Unless the target BTS allocates a code channel, the target BTS includes the code channel that has been indicated by Abis -BTS Setup (step a) in the Abis -BTS Setup Ack. e. The BSC begins to send the forward frames to the target BTS.

37 f. The target BTS transmits the forward frames to the MS. g. The target BTS begins to transmit the forward frames as soon as synchronization has occurred and to send reverse idle frames. The reverse frames contain the timing adjustment information necessary to achieve synchronization. h. If the BSC has chosen to be notified of the start of transmission and reception at the target BTS, when its SDU function and the target BTS have synchronized Abis traffic subchannel, the BSC send an Abis -Traffic Channel Status message to the source BTS i. The BSC sends an Extended / General / Universal Handoff Direction Message to the MS to add the new cell to the active set. j. The MS acknowledges receipt of the Extended / General / Universal Handoff Direction Message with an MS Ack Order. k. The MS indicates successful results of processing the Extended / General / Universal Handoff Direction Message by sending a Handoff Completion message. l. The BSC acknowledges receipt of the Handoff Completion Message by sending a BS Ack Order. 1

38 . SMS Delivery..1 SMS Delivery on the Paging channel This section provides the call flow description for the delivery of an SMS from the MSC to an idle mobile station on the paging channel. MS BTS BSC MSC Data Burst Message MS Ack Order BS AbAbis--PCH Msg. Transfer (Data Burst Message) AbAbis-ACH Msg.Transfer (MS Ack Order) ADDS Page ADDS Page Ack a b c d e f Time Comment Fig. - SMS Delivery on the Paging channel a. When the MSC determines that a point-to-point short message should be sent to an idle MS, the MSC sends ADDS Page message to the BSC. b. The BSC sends the Abis -PCH Msg. Transfer that includes a Data Burst Message. The Data Burst Message contains the short message in received ADDS Page. c. The BTS transfers the Data Burst Message which is included in the Abis -PCH Msg. Transfer message, on a Paging Channel. d. The MS acknowledges the receipt of the Data Burst Message, if it is required. e. The BTS sends the Abis -ACH Msg. Transfer message that contains an MS Ack Order Message. f. The BSC sends ADDS Page Ack to acknowledge the ADDS Page. 1

39 .. SMS Delivery on the Access channel This section provides the call flow description for the delivery of an SMS from an idle mobile station to the MSC on the access channel. BS MS BTS BSC MSC Time Comment Data Burst Message BS Ack Order AbAbis-ACH Msg. Transfer (Data Burst) AbAbis-PCH Msg.Transfer (BS Ack Order) ADDS Transfer a b c d e Fig. - SMS Delivery on the Access channel a. The MS sends a Data Burst Message on the Access Channel to transfer the SMS message. b. The BTS sends the Abis -ACH Msg. Transfer message that includes the Data Burst Message received on the Access Channel. c. The BSC sends the ADDS Transfer message to the MSC containing the Data Burst Message received from the MS in the ADDS User Part element. d. The BTS sends the Abis -PCH Msg. Transfer message that includes the BS Acknowledge Order Message to acknowledge the Data Burst Message, if it is required. e. The BTS sends the BS Ack Order included in the Abis -PCH Msg. Transfer message.

40 .. SMS Delivery on the Traffic channel to MS This section provides the call flow description for the delivery of an SMS from the MSC to a mobile station operating on the traffic channel. BS MS BTS BSC MSC ADDS Deliver AAbis-IS-000 FCH Fwd (Data Burst Message) Data Burst Message MS Ack Order AAbis-IS-000 FCH Rvs (MS Ack Order) ADDS Deliver Ack a b c d e f Time Comment Fig. - SMS Delivery on the Traffic channel to MS 1 1 a. When the MSC determines that a point-to-point short message should be sent to an MS operating on a traffic channel, the MSC sends ADDS Deliver message to the BSC. b. The BSC sends Abis -IS-000 FCH Fwd containing the Data Burst Message c. The Data Burst Message is sent on the traffic channel. d. The MS acknowledges the receipt of the Data Burst Message, if it is required. e. The BTS sends Abis -IS-000 FCH Rvs containing the MS Ack Order. f. The BSC sends ADDS Deliver Ack to acknowledge the ADDS Deliver. 1 1

41 .. SMS Delivery on the Traffic channel from MS This section provides the call flow description for the delivery of an SMS from a mobile station operating on the traffic channel to the MSC. MS BTS BSC MSC Data Burst Message BS Ack Order BS AbA-IS-000 FCH Rvs (Data Burst Message) AbA-IS-000 FCH Fwd (BS Ack Order) ADDS Deliver a b c d e Time Comment Fig. - SMS Delivery on the Traffic channel from MS a. The MS sends a Data Burst Message to the BTS on the Access Channel to transfer the SMS message. b. The BTS sends Abis -IS-000 FCH Rvs containing the Data Burst Message to the BSC. c. The BS sends an ADDS Deliver message to the MSC. The ADDS User Part element contains the SMS message. d. The BSC sends an Abis -IS-000 Fwd message and includes the BS Ack Order to acknowledge receipt of the Data Burst Message, if it is required. e. The BTS transfer the MS Ack Order. 1 1

42 . Traffic Burst Operation..1 Initial Traffic Burst Example Abis Connection Not Yet Established The example below describes the support of traffic burst operation when the Abis connection has not yet been established. MS BTS BSC MSC Time Comment SCRM AbAbis-BTS Setup AAbis-Connect AAbis-Connect Ack AbAbis-BTS Setup Ack AbAbis-Burst Request AbAbis-Burst Response AbAbis-Burst Commit ESCAM Layer Ack Forward and/or reverse traffic burst (data to be sent) a b c d e f g h i j k optional optional Fig. -1 Initial Traffic Burst Example a. Either the BSC receives an indication from the MS (via a SCRM message) or from the network (via data being received from the PDSN) that data needs to be sent to/from the MS. The BSC decides a traffic burst on one or more new cells at a BTS is required in support of a service instance in soft/softer handoff. This example assumes that a Fundamental Channel (FCH) leg already exists on the selected cell(s) at the BTS. b. The BSC assigns an Abis From ID value and sends an Abis BTS Setup message to the BTS to establish an Abis traffic connection to support a Supplemental Channel (SCH) for the call. This example shows only a single Abis connection being established. The BSC is not required to assign a physical Frame Selector at this time.

43 c. The BTS assigns a traffic circuit and optionally a Channel Element ID (CE ID) for each Abis traffic connection and sends an Abis -Connect message to the BSC indicating the Traffic Circuit ID, optional Abis From ID and CE ID to be associated with the specified Abis From ID. The BSC and BTS save the association of CE ID, Traffic Circuit ID, with Cell ID(s). The BSC also saves the Abis From ID value, to be included in subsequent Abis messages to the BTS. This is only done at the initial burst. d. The BSC responds with an Abis Connect Ack message to complete the Abis connection. This includes an Abis From ID value assigned by the BSC, which will be included by the BTS in subsequent Abis messages to the BSC. e. The BTS sends Abis -BTS Setup Ack messages to the BSC to complete the Abis traffic circuit connection setup procedure for the specified set of cells. This includes an Abis From ID value assigned by the BTS, which will be included by the BSC in subsequent Abis messages to the BTS for this call association. When the BSC has knowledge of resources for SCH in the BTS, the procedure at step f and at step g is not necessary. f. The BSC sends an Abis -Burst Request including the Abis to ID to the BTS to request the reservation of the needed radio resources for the supplemental channel. Note that the BSC may send an Abis -Burst Request to the BTS at any time after receiving the Abis -BTS Setup message in step c, and that the set of cells may be subset of the cells assigned in step a-e. g. The BTS determines that it can reserve part or all of the requested resources and sends Abis -Burst Response message(s) including Abis From ID to the BSC indicating the resources that have been reserved and committed to the traffic burst, and the cause value for any uncommitted cells. Each reservation includes a physical Channel Element. Note that the physical Channel Element may be allocated any time after step b. h. The BSC makes a final decision on the resources to be used for the traffic burst and sends an Abis -Burst Commit message to each BTS indicating the set of committed resources that will actually be used for the traffic burst. Note that the BSC may allocate the frame selector any time after step b. Any resources (cells) not included in the Abis -Burst Commit message may be released by the BTS. 0

44 i. The BSC commands the MS to prepare for the traffic burst via an ESCAM message. j. The MS acknowledges the command from the source BS with a Layer Ack. k. The network and MS exchange forward and/or reverse traffic burst information for the specified duration, or until the BSC terminates or extends the traffic burst. 1

45 .. Subsequent Traffic Burst Example The example below describes the support of traffic burst operation when the Abis connection for the supplemental channel (SCH) has already been established. MS BTS BSC MSC Time Comment SCRM AbAbis-Burst Request AbAbis-Burst Response AbAbis-Burst Commit ESCAM Layer Ack Forward and/or reverse traffic burst (data to be sent) a b c d e f g optional optional Fig. -1 Subsequent Traffic Burst Example a. Either the BSC receives an indication from the MS (via a SCRM message) or from the network (via data being received from the PDSN) that data needs to be sent to/from the MS. When the BSC has knowledge of resources for SCH in the BTS, the procedure at step b and at step c is not necessary. b. The BSC decides a traffic burst is required on one or more cells for which an Abis connection already exists in support of a supplemental channel. The BSC sends an Abis -Burst Request to the BTS to request the reservation of the needed radio resources for the supplemental channel. c. The target BS determines that it can reserve part of all of the requested resources and sends Abis -Burst Response massage(s) to the BSC indicating the resources that have been reserved and committed to the traffic burst, and the cause value for any uncommitted cells. Each reservation includes a physical Channel Element. Note that the physical Channel Element may be allocated any time after step b. d. The BSC makes a final decision on the resources to be used for the traffic burst and sends an Abis -Burst Commit message to each BTS indicating the set of committed resources that will actually be used for

46 the traffic burst. Note that the BSC may allocate the frame selector any time after step b. Any resources (cells) not included in the Abis -Burst Commit message may be released by the BTS. e. The BSC commands the MS to prepare for the traffic burst via an ESCAM message. f. The MS acknowledges the command from the source BS with a Layer Ack. g. The network and MS exchange forward and/or reverse traffic burst information for the specified duration, or until the BSC terminates or extends the traffic burst Abis Interface Message Formats For Abis Interface message there are a number of information elements that are individually defined in section.1. Each information element in a given message is tagged with a reference in section.1, a direction indication (i.e., some elements within a message are bi-directional and others are not), and a mandatory/optional type (M/O) indicator. The inclusion of information elements in each message is specified as follows:? M - information elements which are mandatory for the message.? O - information elements which are optional for the message..1 Abis interface message.1.1 Abis-ACH Msg Transfer This Abis interface message is sent from the BTS to the BSC to notify the BSC of the reception of the contained message or Layer acknowledgment on the specified access channel.

47 Information Element Section Reference Element Direction Message Type. BTS -> BSC M Correlation ID. BTS -> BSC Mobile Identity (IMSI/MIN). BTS -> BSC O Mobile Identity (ESN). BTS -> BSC O Cell Identifier. BTS -> BSC Air Interface Message. BTS -> BSC O Manufacturer s Specific Record. BTS -> BSC O O a O b Type 1 a. If this element is included in this message, the value shall be returned in the Abis -ACH Msg Transfer Ack message. b. This element indicates the cell at the BTS on whose acces s channel the air-interface message or Layer acknowledgment was received. The following table shows the bitmap layout for the Abis -ACH Msg Transfer message: 1 0 Octet Message Type = [EH] 1 Correlation ID: Abis Element Identifier = [1H] 1 Length = [0H] (MSB) Correlation Value = <any value> (LSB) Mobile Identity (IMSI): A1 Element Identifier = [0DH] 1 Identity Digit 1 = [0H-H] (BCD) Length = [0H-0H] (-1 digits) Odd/even Indicator = [1,0] Type of Identity = [1] (IMSI) Identity Digit = [0H-H] (BCD) Identity Digit = [0H-H] (BCD) Identity Digit N+1 = [0H-H] (BCD) Identity Digit N = [0H-H] (BCD) n = [] (if even number of digits) Identity Digit N+ = [0H-H] (BCD) n+1 Mobile Identity (ESN): A1 Element Identifier = [0DH] 1 Length = [0H]