Pilot Beacon and Candidate Frequency Search

PilotBeaconAndCandidateFreqSearch
在C.S0005-A 中定義Pilot Beacon為只做傳送的基站, 它廣播Pilot Channel及Sync Channel, 也可選項送出Paging Channel或Broadcast Control Channel
手機量測pilot beacon信號以輔助CDMA hard handoff及inter-frequency idle-mode handoff
平常手機在Idle mode的時候, 每當監視Paging Channel或f-ccch時, 手機會在對應的CDMA Frequency Assignment頻率上持續尋找最強的pilot channel signal, 這種頻率有可能與目前的serving頻率不同, 例如Neighbor Set中指定不同頻率上的pilot信號
基站可透過Candidate Frequency Search Request Message要求手機尋找與目前使用的frequency不相同的CDMA frequency, 以便偵測可用的CDMA Channel並測量它們的信號強度, 手機會以Candidate Frequency Search Report Message上報該信號強度給基站, 基站可以依據上報信息中的pilot strength measurements要求手機執行inter-frequency hard handoff
當手機收到基站發出Candidate Frequency Search Request Message要求時, 手機可能回應Mobile Station Reject Order Message以拒絕請求的原因包括invalid Frequency Assigment (同頻錯誤), Search Set Not Specified (空的Search Set), Search Period Too Short (搜尋期過短), 基站要求的搜尋請求模式可以為single search或periodic search
依據Candidate Frequency Search Set的指定尋找所有的Pilot信號強度時, 手機會先停止處理f-fch, f-fcch, f-dcch, f-sch, f-scch, r-fch, r-dcch, 也會暫停目前Active Set及Candidate Set的fader timer及handoff drop timer, 同時停止累積closed loop mean output power的level改變, 此後才調整至Candidate Frequency進行一次或多次量測
有關手機在Forward Traffic Channel中收到與Handoff相關的message時細部處理細節載於C.S0005-A 的2.6.6.2.5.1, 這種messages包括
Pilot Measurement Request Order,
Analog Handoff Direction Message,
Neighbor List Update Message,
Extended Handoff Direction Message,
Candidate Frequency Search Request Message,
Candidate Frequency Search Control Message,
Extended Neighbor List Update Message,
Supplemental Channel Assignment Message,
General Handoff Direction Message,
Periodic Pilot Measurement Request Order,
Universal Handoff Direction Message,
Mobile Assisted Burst Operation Parameters Message
Extended Supplemental Channel Assignment Message
Forward Supplemental Channel Assignment Mini Message
Reverse Supplemental Channel Assignment Mini Message