2section (Continued) 6 Layer 3 Processing

Pilot Strength Measurements

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2.6.6.2.3 Handoff Drop Timer

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.

For an SR1 pilot, the mobile station should use the searcher element (see [2]) to compute the strength of a pilot (PS) by adding the ratios of received pilot energy per chip, E_c, to total received spectral density (noise and signals), I_o, of at most k usable multipath components, where k is the number of demodulating elements (see [2]) supported by the mobile station.

For an SR3 pilot, the pilot strength is given by

where:

is the pilot Ec/Io measured on the Primary carrier (computed as specified above for SR1 pilots),
is the pilot Ec/Io measured on the pilot on the lower frequency of the two remaining SR3 frequencies (computed as specified above for SR1 pilots), and is the pilot power level on the lower frequency of the two remaining SR3 frequencies relative to that of the primary SR3 pilot, i.e. = .
is the pilot Ec/Io measured on the pilot on the higher frequency of the two remaining SR3 frequencies (computed as specified above for SR1 pilots), and is the pilot power level on the higher frequency of the two remaining SR3 frequencies relative to that of the primary SR3 pilot, i.e. = .

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_USE_s is less than or equal to three or SOFT_SLOPE_s 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_DROP_s. The mobile station shall reset and disable the timer if the strength of the corresponding pilot exceeds T_DROP_s.

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

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

• For the Active Set, the mobile station shall sort the N_A pilots in the Active Set in order of increasing strengths, i.e., PS₁ < PS₂ < PS₃ < …< PS_N_Awhere the strength PS is as defined in 2.6.6.2.2. The mobile station shall start the timer whenever the strength PS_i 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_TDROP_RANGE_s is equal to '0000' or if P_REV_IN_USE_s is less than 9, then the mobile station shall perform the following:

• If T_TDROP_s 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_TDROP_s. If T_TDROP_s 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

Otherwise, the mobile shall perform the following:

• The mobile station shall select the timer expiration value as follows:

The mobile station shall select the timer expiration value greater than or equal to the minimum drop timer value computed as:

max ( 0.1 seconds, range-based minimum timer expiration value ),

where the range-based minimum timer expiration value equals:

( nominal timer expiration value ) – ( timer expiration range value ),

where:

the nominal timer expiration value is the timer expiration value in Table 2.6.6.2.3-1 corresponding to T_TDROP_s and,
the timer expiration range value is the timer expiration range value in Table 2.6.6.2.3-2 corresponding to T_TDROP_RANGE_s.

The mobile station shall select the timer expiration value less than or equal to the maximum drop timer value which equals:

( nominal timer expiration value ) + ( timer expiration range value ),

where:

the nominal timer expiration value is the timer expiration value in Table 2.6.6.2.3-1 corresponding to T_TDROP_s and,

the timer expiration range value is the timer expiration range value in Table 2.6.6.2.3-2 corresponding to T_TDROP_RANGE_s.

If the mobile station selected a timer expiration value of 0.1s then the mobile station shall consider the timer expired within 100 ms of enabling it.

Table 2.6.6.2.3-2. Handoff Drop Timer Expiration Range Values

T_TDROP_RANGE [binary]	Timer Expiration Range (seconds)	T_TDROP_RANGE [binary]	Timer Expiration Range (seconds)
0000	0	1000	27
0001	1	1001	39
0010	2	1010	55
0011	4	1011	79
0100	6	1100	112
0101	9	1101	159
0110	13	1110	225
0111	19	1111	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.

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