PILOT_PN
Definition: PILOT_PN is the pilot PN sequence offset expressed in multiples of 64 PN chips. The function of the different PILOT_PN values is to allow each base station to transmit signals which are statistically uncorrelated, and there-fore separable and non-interfering, by virtue of their being delays of one another by multiples of 64 chips. The short pilot code has a period of exactly 215 or 32,768 chips. Therefore, there are exactly 32,768/64 or 512 pilot offsets of 64 chips each. Since 512 equals 29, the PILOT_PN offset is sent via a 9 binary-bit word.
PILOT_PN
Application: At a PN chipping rate of 1.2288 Mchips/sec, 64 chips occur every 52.083 µsec. This time delay is equivalent to about 9.7 statute miles. A mobile which is about 9.7 statute miles closer to one base station than to another would receive the same PN-code chips from both base stations if the two stations were only offset by one PILOT_PN unit. Typically, in practice, PILOT_PN offsets are chosen to be multiples of 4, or at least 2, times the 64-PN chips. With these larger PILOT_PN offset, pilots arriving at a mobile with the same PN-chips do not interfere with one another because they arrive at dramatically different power levels. Typical PILOT_PN values assigned to base stations might well equal zero, 4, 8, 12 etc.
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