2. section (Continued) 6 Call Layer 3 Processing



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2.6.6.2.7 Soft Handoff
2.6.6.2.7.1 Forward Traffic Channel Processing

All Forward Traffic Channels associated with pilots in the Active Set of the mobile station carry identical modulation symbols with the exception of the power control subchannel (see TIA/EIA/IS-2000-2).

When the Active Set contains more than one pilot, the mobile station should provide diversity combining of the associated Forward Traffic Channels. The mobile station shall provide for differential propagation delays from zero to at least 150 s.


2.6.6.2.7.2 Reverse Traffic Channel Power Control During Soft Handoff

The Extended Handoff Direction Message, a General Handoff Direction Message or a Universal Handoff Direction Message identifies sets of Forward Fundamental Code Channels or Forward Dedicated Control Channels that carry identical closed loop power control subchannels. A set consists of one or more Forward Fundamental Code Channels or Forward Dedicated Control Channels with identical power control information.

In each power control group containing valid power control bits (see TIA/EIA/IS-2000-2), the mobile station should provide diversity combining of the identical closed loop power control subchannels and shall obtain at most one power control bit from each set of identical closed loop power control subchannels. The mobile station should only combine reliable power control bits (see 9.3.8 of TIA/EIA-98-C) as follows:

• If the reliable power control bits obtained from all sets are equal to ‘0’, the mobile station shall increase its power as specified in TIA/EIA/IS-2000-2.

• If the reliable power control bit obtained from any set is equal to ‘1’, the mobile station shall decrease its power as specified in TIA/EIA/IS-2000-2.


2.6.6.2.7.3 Starting Periodic Search following Soft Handoff

If the PERIODIC SEARCHs is equal to ‘1’, a periodic search is not already in progress, and the Frequency Assignment after handoff is different from the Candidate Frequency (CDMABANDs is not equal to CF_CDMABANDs or CDMACHs is not equal to CF_CDMACHs), the mobile station shall do the following:

• If the mobile station uses received power measurements in the search procedure, it should start monitoring the received power on the Target Frequency and should maintain an average of the received power over the last N12m frames.

• The mobile station shall start a periodic search as described in 2.6.6.2.8.3.2.

2.6.6.2.8 CDMA-to-CDMA Hard Handoff

The base station directs the mobile station to perform a CDMA-to-CDMA hard handoff by sending an Extended Handoff Direction Message, a General Handoff Direction Message or a Universal Handoff Direction Message in which the mobile station is transitioned between disjoint sets of base stations, different Frequency Assignments, or different frame offsets. If RETURN_IF_HANDOFF_FAILs is equal to ‘0’, the mobile station performs the actions described in 2.6.6.2.8.1. If RETURN_IF_HANDOFF_FAILs is equal to ‘1’, the mobile station performs the actions described in 2.6.6.2.8.2.
2.6.6.2.8.1 Hard Handoff without Return on Failure

At the action time specified of the Extended Handoff Direction Message, the General Handoff Direction Message or Universal Handoff Direction Message the mobile station shall disable its transmitter, reset the fade timer specified in 2.6.4.1.8, suspend incrementing TOT_FRAMESs and BAD_FRAMESs as specified in 2.6.4.1.1, and tune to the assigned Forward Traffic Channel. The mobile station shall perform acquisition of the pilots in the new Active Set.

If a periodic Serving Frequency pilot report procedure is in progress, the mobile station shall abort it (see 2.6.6.2.12).

The mobile station shall begin monitoring the assigned Forward Traffic Channel within the time specified below:

• If the Extended Handoff Direction Message, General Handoff Direction Message or Universal Handoff Direction Message specifies a CDMA Frequency Assignment different from the Serving Frequency and an Active Set containing pilots with pilot PN sequence offsets identical to those of the pilots in the Serving Frequency Active Set, the mobile station shall begin monitoring the assigned Forward Traffic Channel within T60m seconds after the action time.

• If the Extended Handoff Direction Message, General Handoff Direction Message or Universal Handoff Direction Message specifies a CDMA Frequency Assignment different from the Serving Frequency and an Active Set containing a pilot with pilot PN sequence offset not equal to that of any pilot in the Serving Frequency Active Set, the mobile station shall begin monitoring the assigned Forward Traffic Channel within T61m seconds after the action time.

• If the Extended Handoff Direction Message, General Handoff Direction Message or Universal Handoff Direction Message specifies a CDMA-to-CDMA hard handoff without changing the CDMA Frequency Assignment, the mobile station shall begin monitoring the assigned Forward Traffic Channel within T62m seconds after the action time.

Upon receiving a period of (N11m  20) ms with sufficient signal quality (e.g. good frames) on the physical channel corresponding to FPC_PRI_CHANs on the assigned Forward Traffic Channel, the mobile station shall re-enable its transmitter. The mobile station shall transmit the Traffic Channel Preamble, as described in 2.1.3.6.2.3 of TIA/EIA/IS-2000-2, followed by a Handoff Completion Message.

Upon receiving a period of (N3m  20) ms with sufficient signal quality (e.g. good frames) on the physical channel corresponding to FPC_PRI_CHANs, the mobile station shall resume incrementing TOT_FRAMESs and BAD_FRAMESs as specified in 2.6.4.1.1.

If the PERIODIC SEARCHs is equal to ‘1’, a periodic search is not already in progress, and the Frequency Assignment after handoff is different from the Candidate Frequency (CDMABANDs is not equal to CF_CDMABANDs or CDMACHs is not equal to CF_CDMACHs), the mobile station shall do the following:

• If the mobile station uses received power measurements in the search procedure, it should start monitoring the received power on the Target Frequency and should maintain an average of the received power over the last N12m frames.

• The mobile station shall start a periodic search as described in 2.6.6.2.8.3.2.



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