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Title: Comments on CDMA2000 1x Rev E One-Bit-Fix in SPM
Abstract: This contribution proposes comments on the one-bit-fix in SPM of cdma2000 Rev E to solve a particular industry issue.
Recommendation: Review and Adopt
Source: Contact: Yuezheng Wang [email protected], yu.yuanfang, lu.ting, [email protected] [email protected]
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Background
Background According to CDMA2000 1x Rev E Implementation Guide Line, the Rev E capable
mobile station can send an ORM or PRM or STRPM with REV_FCH_RC_MAP and
FOR_FCH_RC_MAP to indicate its RC8 and RC11/12 capability.
C22-20101206-009 reports there is a “RC bug” in CDMA2000 1x Rev E
Implementation Guide: in some deployment, the legacy 1x base stations cannot
recognize the size-increased FOR_FCH_RC_MAP or REV_FCH_RC_MAP in ORM,
PRM or STRPM, and cause MO and MT call failure.
C22-20110314-005 proposed an “One-Bit Fix” in SPM. i.e. using one bit indication in
SPM to indicate the base station’s RC capability. However this “One-Bit Fix” added
in SPM will cause other issues.
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Comments
Handoff Issue When a Rev E capable mobile station sets up a call with a legacy 1x base station, it
may use a legacy RC (such as RC1 or 3) for the voice call.
According to the proposed “One-Bit-Fix” in C.S0005 Rev E spec and Implementation
Guideline, the Rev E capable mobile station shall not report its Rev E capability in
RC_MAPs.
When this Rev E capable mobile station moves to the boundary of 1x Rev E base
stations, it may trigger handoff to a Rev E base station. The target Rev E base
station has to use the legacy RC for the handoff and remains it for the call.
The Rev E mobile station follows the “One-Bit Fix” indication in SPM to report its RC
capability.
The “One-Bit-Fix” indication is only allowed to transmit over PCH. The mobile station
cannot update the base station RC capability information during the call. Therefore,
the mobile station will never report its Rev E RC capability if the base station sends
a STRQM after handoff. The Rev E base station has no way to upgrade the voice
call to RC8/11.
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Rev E MS Handoff from Legacy 1x to Rev E BS
Rev E MS Legacy BS
1. Voice Traffic (RC3, SO3)
6. UHDM (RC3, SO3)
Rev E BSMSCs
2. Handoff Required (RC3, SO3)
3. Handoff Request (RC3, SO3)
4. Handoff Request Ack (SO3)
5. Handoff Command (SO3)
7. MS Ack Order8. Handoff Commenced
11. Handoff Complete Message
9. Reverse Traffic Channel Preamble or Frame
10. BS Ack Order
12. Voice Traffic (RC3, SO3)
13. STRQM
14. STRPM (RC3, SO3)
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Comments
Impact on Rev E System Performance Rev E system could achieve up to 4 times performance improvement from the
legacy 1x system. But the real performance improvement depends operators’
deployment.
Operator may only deploy Rev E base stations in some high population density area for
capacity improvement and cost reduction.
Consequently, the Rev E base stations may be surrounded by legacy 1x base stations
which may not have the particular industry issue.
Now the “One-Bit-Fix” in SPM forces all the Rev E base stations adjacent to any kind
of legacy 1x base stations (even they do not have the particular industry issue
currently) to face the handoff issue and cannot upgrade the voice call to using
RC8/11.
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Comments
Impact on Rev E System Performance (continued)
Rev E BS
Rev E BS
Rev E BS
Any Legacy 1x
Any Legacy 1x
MS handoff to Rev EFrom any legacy 1x
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Suggestions
One Bit Indication in Other Messages Add the one-bit indication in the ITSPM and STRQM to indicate base station
capability
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Rev E MS Handoff from Legacy 1x to Rev E BS
Rev E MS Legacy BS
1. Voice Traffic (RC3, SO3)
6. UHDM (RC3, SO3)
Rev E BSMSCs
2. Handoff Required (RC3, SO3)
3. Handoff Request (RC3, SO3)
4. Handoff Request Ack (SO3)
5. Handoff Command (SO3)
7. MS Ack Order8. Handoff Commenced
11. Handoff Complete Message
9. Reverse Traffic Channel Preamble or Frame
10. BS Ack Order
12. Voice Traffic (RC3, SO3)
14. STRQM (BS_EXT_RC_IND)
15. STRPM (RC8/11, SO73)
13. ITSPM (BS_EXT_RC_IND)
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Benefits
The “One Bit Indication in Other Messages ” proposal gives the target Rev E
base station ability to trigger mobile station reporting its Rev E RC capability
after handoff. Then the target base station could have the chance to upgrade
the voice call to RC8/11 based on its own requirement. Such upgrade will help
to achieve voice capacity improvement for Rev E base station.
