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ANSI TIA/EIA/95-B Enhancements and New Features

ANSI TIA/EIA/95-B Enhancements and New Features. Motorola Asia Pacific Limited Asia Pacific Cellular Infrastructure Group Competency Center - Systems Engineering April 21, 1999. Purpose of ANSI-95-B. Improve call quality

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ANSI TIA/EIA/95-B Enhancements and New Features

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  1. ANSI TIA/EIA/95-BEnhancements and New Features Motorola Asia Pacific Limited Asia Pacific Cellular Infrastructure Group Competency Center - Systems Engineering April 21, 1999

  2. Purpose of ANSI-95-B • Improve call quality • IS-95-A was the first commercial version of CDMA, and provided good data for where enhancements could be made • ANSI-95-B provides features that can improve call setup rates and reduce dropped call rates • Enhance system performance • Improvement in capacity • Reduce excessive soft handoff • Introduce new subscriber features • New features that GSM/TDMA may potentially provide • New features that give CDMA a potential “edge” over other technologies

  3. List of Features/Enhancements • Call Quality and System Performance • Channel Assignment into Soft Handoff • Access Entry Handoff • Access Probe and Access Handoff • Interference Correction • New Soft Handoff Algorithm • Release Order on Access Channel • Increase in Value of N1m • Change in Timers T50m and T51m • Neighbor Search Enhancements • Inter-frequency Mobile Assisted Hard Handoff

  4. List of Features/Enhancements(cont.) • Subscriber Features • IMSI and TMSI Support • Calling Number Identification Presentation (CNIP) • Calling Name Presentation (CNAP) • PIP Tone • Priority Access and Channel Assignment (PACA) • Network Directed System Selection (NDSS) • Network-based Features • Wireless Local Loop • Location Determination Functionality (Power-Up Function) • High Speed Data Framework

  5. Handoff Enhancements • Channel Assignment into soft handoff • IS-95-A only allows ONE pilot to be assigned when the call is first set up • Calls can drop during channel assignment procedure if the assigned pilot is not “strong” enough • ANSI-95-B allows assigning of MULTIPLE pilots during channel assignment • Increases call setup successful rates • Paging Channel handoffs • Mobile Station is allowed to perform Paging Channel handoff during system access • Reduces the probability of dropping a call during setup procedures

  6. CAM: Channel Assignment Message Page Resp Page Resp Page Resp Traffic ChannelInitialization BS Ack Overhead Information Page CAM Access EntryHandoff Access Handoff Access ProbeHandoff “Paging Channel” Handoff • Access Entry Handoff • Improves mobile termination rates • Access Handoff and Access Probe Handoff • Improves call origination and termination rates Purpose is to improve call setup success rate by increasing the probability of a successful mobile access attempt

  7. Characteristics of Access Probe and Access Handoff • Impact on pilot reporting in Access Channel messages: • Flags to indicate which one was the “first” pilot accessed and which one was the “next to last” pilot accessed • “Access Handoff” enable flag to indicate the set of pilots in the access handoff list • “Access Attempted” flag to indicate the set of pilots on which an access probe has been sent by the MS • MS is NOT allowed to change the Access Handoff List (maximum of six) after the first probe • Channel Assignment Messages may be broadcast • First BS acts as “anchor”; MS uses RAND from the first BS • Access attempt aborted if message length exceeds MAX_CAP_SIZE in the new BS • Layer 2 Sequence Number remains the same for each probe

  8. Handoff Enhancements (cont.) • New Soft Handoff Algorithm • Addresses the problem of excessive shuffling of the pilots in the Active Set (i.e., pilots in soft handoff) • New algorithm in the mobile station will reduce the rate at which pilots are added or dropped from the Active Set • Results in improvement in system capacity • Primarily impacts the mobile stations • Inter-Frequency Mobile Assisted Hard Handoff (MAHHO) • A new scheme intended to ultimately replace use of Pilot Beacons for inter-frequency hard handoff • MS performs measurements on a different frequency while still on call • MS is off traffic channel during the search period • Voice quality may be affected during the search period

  9. BTS/CBSC/MSC Mobile Candidate Frequency Search Request Message Candidate Frequency Search Response Message BS “commands” the MS to start the search; search type (single or periodic) is included. Candidate Frequency Search Control Message Candidate Frequency Search Report Message Inter-Frequency MAHHO Call Flow Example BS specifies the candidate frequency, pilots on candidate frequency, candidate frequency characteristics, search type, search period, search mode, etc. MS specifies search time estimate, max. time off Forward and Reverse Traffic Channel. MS re-tunes to the candidate frequency at specified time and takes measurements. Report sent after return to Traffic Channel for one time search; for periodic search, report sent when the power above a certain threshold. Candidate Frequency Search Request Message can be used to start the search if the BS knows the characteristics (such as search capabilities) of the MS.

  10. Inter-Frequency MAHHO with Return on Failure • Search of candidate frequency can also be triggered by a General Handoff Direction Message with RETURN_IF_HANDOFF_FAIL set • General Handoff Direction Message can specify periodic search • MS sends Candidate Frequency Search Report Message if hard handoff is unsuccessful • “Successful” handoff defined as MS receiving N11m consecutive good frames on the Forward Traffic Channel

  11. Increase in value of N1m • N 1m (# of message retries on Reverse Traffic Channel) increased from 3 to 9 • Driven by AirTouch data • Increases the probability of MS receiving Layer 2 Ack • Reduces the probability of a call being dropped

  12. Change in timer T50m and T51m • T50m (maximum time to obtain N5m consecutive good Forward Traffic Channel frames) increased from 0.2 sec to 1 sec • T51m (maximum time for the MS to receive a BS Ack) started only after first occurrence of receiving N5m consecutive good Forward Traffic Channel frames, thus “extending” the timer value • Increase in timer values expected to reduce dropped calls during Traffic Channel initialization

  13. Neighbor Search Enhancements • Increase in the handoff speed by improving neighbor search performance • The improved algorithm will reduce dropped call rates • New Forward Traffic Channel message - Extended Neighbor List Update Message • Message includes a per neighbor search window size and search priority • Priority concept same as that in the J-STD-008 Extended Neighbor List Message on the PCH • Interpretation of “priority” up to the implementation

  14. IMSI and TMSI Support • International Mobile Subscriber Identity (IMSI) is defined by ITU-T (International Telecommunication Union - Telecommunications Standardization Sector) • IMSI is a 15 digit address that will ultimately replace MIN • IMSI is a key enabler for global roaming • Temporary Mobile Station Identity (TMSI) concept is similar to GSM systems • TMSI provides privacy to the end-user, since it prevents use of IMSI for addressing for every message exchange • TMSI addressing may also save some signaling capacity, since fewer than 15 digits can be used for addressing • TMSI is assigned, deleted, and reassigned by the network

  15. Calling Number Identification Presentation (CNIP) • IS-95-A only included Calling Party Number and Connected Number Information Records in the forward direction • ANSI-95-B adds the following Information Records: • Calling Party Subaddress, Connected Subaddress • Redirecting Number, Redirecting Subaddress • On the Reverse Traffic Channel, the MS is allowed to send Calling Party Subaddress and/or Called Party Subaddress in Flash with Information or Origination Continuation Message • Origination Message modified to indicate if more records are to be expected in Origination Continuation Message

  16. Calling Name Presentation (CNAP) • IS-95-A supports transmission of Calling Party Number to the called party’s mobile station • ANSI-95-B provides the ability to transmit Calling Party Name to the called party’s mobile station • CNAP is based on ISDN specification for the similar feature (ANSI T1.610) • Calling Name is conveyed as a “Display” record from infrastructure to the mobile station • In addition to Calling Name, time and date may also be displayed • Requires additional capabilities in the infrastructure to look up the “Name”

  17. Priority Access Channel Assignment(PACA) • Priority calls in emergency situations • Potentially a value-added service • Feature assumes use of “queuing” • Two new messages - PACA Message on the Paging Channel, and PACA Cancel Message on the Access Channel • MS required to have the capability to re-originate • MS should have the capability to display queue position • PACA call is canceled if the user decides to originate another call, or if the MS receives a Page

  18. Network Directed System SelectionBackground/Purpose • Commonly referred to as NDSS • A feature that allows the MS to “automatically” register with a “preferred” system while roaming, or to be directed by a service provider to a “preferred” system • MS may be redirected to analog or CDMA system, and on any band • NDSS will require some significant business agreements between the service providers • A “network” based alternate to “handset” based System Selection for Preferred Roaming (SSPR) approach • Success of the feature questionable especially if SSPR becomes dominant in the market

  19. Wireless Local Loop (WLL) Extensions • CDMA being promoted as solution for WLL • Basic POTS functionality addressed • Three new Information Records on the forward link: • Meter Pulse (sent on the Traffic Channel) • Allows BS to send toll information • Identifies the number of meter pulses and frequency of the alert tone • Parametric Alerting (sent on Paging or Traffic Channel) • Used to deliver in-band ringing • Flexible definition of cadence and number of tones • Line Control (sent on the Traffic Channel) • Allows BS to control state of the line port attached to terminal • Ability to deny power and set line polarity included

  20. High Speed Data Support • ANSI-95-B provides the framework for data rates comparable to wireline ISDN networks • Services that use the framework will be defined in future • Radio Link Protocol (RLP) for higher rate data services are defined in IS-707-A • Up to eight 9.6 or 14.4 kbps code channels assigned to forward and reverse Traffic Channel based on user bandwidth needs • Fundamental (always 1) and supplemental (0 to 7) • Number of forward and reverse channels independent • Fundamental - variable rate Supplemental - full rate • Forward channel Walsh codes assigned by CBSC

  21. Power Up Function (PUF) for Location Determination • MS increases its power on “command” from BS, thus making it visible to more BSs • Information used in triangulation techniques to locate the MS • A “tool” to meet US Government’s requirements for location estimation related to emergency services • Potentially a key enabler for other location-based services • Available only on the Traffic Channel • Similar method being investigated for Paging Channel, could be added in the next revision of ANSI-95-B

  22. Miscellaneous Improvements • Band Class included in Channel Assignment Message and Analog Handoff Direction Message • Allows channel assignment or handoff to an analog system in a different band (other than just 800 MHz) • Makes the message consistent with CDMA/TACS specification • Enhanced Channel Assignment • In IS-95-A, GRANTED_MODE “00” implied Rate Set 1 • DEFAULT_CONFIG added to specify Rate Set 1 or Rate Set 2 • Compatibility Support • P_REV (BS’s protocol revision) and MIN_P_REV added to Extended System Parameters Message • P_REV also added to Extended Handoff Direction Message • Concept of P_REV_IN_USE at the MS • Many BS procedures based on checking MOB_P_REV

  23. Miscellaneous Improvements (cont’d) • DTMF Operation Clarifications • Problems: • Inconsistent timing at the handset and end system • Sequencing when MS sends multiple Send Burst DTMF Messages • Mixed use of Send Burst DTMF Message and Continuous DTMF Tone Order • Solution: • MS recommended to follow timing requirements included in IS-95 • MS required to preserve relative ordering of digits • MS required to send an Order indicating completion of a continuous digit before sending another digit via either message

  24. Miscellaneous Improvements (cont’d) • Search window size for Neighbor and Remaining set included in Extended Handoff Direction Message • Eliminates the need to send this information via In-Traffic System Parameters Message • International support • Support for Japan-specific services • Globalization of IS-95 • “International Data Burst Type” indicator added • “International Information Record Type” indicator added • Redirection Record Types reserved for TACS and JTACS

  25. Miscellaneous Improvements (cont’d) • PIP Tone • Used to indicate that the user has a message waiting • Tone delivered on Paging and Traffic Channels using Signal Information Record • New Mobile Station Reject Orders added for some specific failure scenarios (e.g., Information Record not supported for a particular Band Class or Operating Mode) • Closed Loop Power Control Modification • Improvement in reverse link power control • Applicable to CDMA high speed data services

  26. Conclusion • ANSI-95-B is embraced by the industry • ANSI-95-B improves call quality • ANSI-95-B improves call setup rates and reduce dropped call rates • ANSI-95-B enhances system performance • Improvement in capacity • Reduce excessive soft handoff

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