2. section (Continued) 6 Call Layer 3 Processing


Pilot Strength Measurements



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2.6.6.2.2 Pilot Strength Measurements

The mobile station assists the base station in the handoff process and in the Reverse Supplemental Code Channel operation and in the Reverse Supplemental Channel operation by measuring and reporting the strengths of received pilots.

The mobile station should use the searcher element (see TIA/EIA/IS-2000-2) to compute the strength of a pilot (PS) by adding the ratios of received pilot energy per chip, Ec, to total received spectral density (noise and signals), Io, of at most k usable multipath components, where k is the number of demodulating elements (see TIA/EIA/IS-2000-2) supported by the mobile station.


2.6.6.2.3 Handoff Drop Timer

The mobile station shall maintain a handoff drop timer for each pilot in the Active Set and Candidate Set.

If P_REV_IN_USEs is less than or equal to three or SOFT_SLOPEs is equal to ‘000000’, the mobile station shall perform the following:

For the Candidate Set, the mobile station shall start the timer whenever the strength of the corresponding pilot becomes less than T_DROPs. The mobile station shall reset and disable the timer if the strength of the corresponding pilot exceeds T_DROPs.

• For the Active Set, the mobile station shall start the timer whenever the strength of the corresponding pilot becomes less than T_DROPs. The mobile station shall start the timer even if the timer has previously expired. The mobile station shall reset and disable the timer if the strength of the corresponding pilot exceeds T_DROPs.

If P_REV_IN_USEs is greater than three and SOFT_SLOPEs is not equal to ‘000000’, the mobile station shall perform the following:

• For the Candidate Set, the mobile station shall start the timer whenever the strength of the corresponding pilot becomes less than T_DROPs. The mobile station shall reset and disable the timer if the strength of the corresponding pilot exceeds T_DROPs.

• For the Active Set, the mobile station shall sort the NA pilots in the Active Set in order of increasing strengths, i.e., PS1 < PS2 < PS3 < …< PSNA where the strength PS is as defined in 2.6.6.2.2. The mobile station shall start the timer whenever the strength PSi satisfies the following inequality:


For the Active Set, the mobile station shall start the timer even if the timer has previously expired. The mobile station shall reset and disable the timer whenever the above inequality is not satisfied for the corresponding pilot.

If T_TDROPs equals zero, the mobile station shall consider the timer expired within 100 ms of enabling it. Otherwise, the mobile station shall consider the timer expired within 10% of the timer expiration value shown in Table 2.6.6.2.3-1 corresponding to T_TDROPs. If T_TDROPs changes, the mobile station shall begin using the new value for all handoff drop timers within 100 ms.


Table 2.6.6.2.3-1. Handoff Drop Timer Expiration Values

T_TDROP

Timer
Expiration
(seconds)


T_TDROP

Timer
Expiration
(seconds)


0

 0.1

8

27

1

1

9

39

2

2

10

55

3

4

11

79

4

6

12

112

5

9

13

159

6

13

14

225

7

19

15

319

The mobile station shall indicate the status of the handoff drop timer for all pilots in the Active Set and Candidate Set when transmitting a Pilot Strength Measurement Message or an Extended Pilot Strength Measurement Message.


2.6.6.2.4 Pilot PN Phase

The mobile station shall measure the arrival time, PILOT_ARRIVAL, for each pilot reported to the base station. The pilot arrival time shall be the time of occurrence, as measured at the mobile station antenna connector, of the earliest arriving usable multipath component of the pilot. The arrival time shall be measured relative to the mobile station’s time reference (see TIA/EIA/IS-2000-2) in units of PN chips. The mobile station shall compute the reported pilot PN phase, PILOT_PN_PHASE, as

PILOT_PN_PHASE = (PILOT_ARRIVAL + (64  PILOT_PN)) mod 215,

where PILOT_PN is the PN sequence offset index of the pilot (see TIA/EIA/IS-2000-2).

2.6.6.2.5 Handoff Messages



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