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CDMA 120 – cdmaOne and CDMA2000 Concepts and Terminology phần 8

Nếu việc thăm dò không được công nhận, điện thoại di động sẽ truyền tải cùng một tàu thăm dò tại một thời gian ngẫu nhiên sau này, nói chung ở mức độ cao hơn của quyền lực. Sau khi truyền lại một số, điện thoại di động sẽ khai báo một thất bại truy cập và reinitialize. | 80-13321-1 X11 CDMA 120 - cdmaOne and CDMA2000 Concepts and Terminology Section Handoffs Hard Handoffs A hard handoff entails a brief disconnection from a current serving cell prior to establishing a connection with a target cell. Hard handoffs can occur for several reasons. The figure illustrates a hard handoff from a CDMA system to an analog system. Hard handoffs however may also occur between CDMA cells. CDMA-to-CDMA hard handoffs are due to frequency mismatches frame offset misalignment or disjoint cells cells served by different BSCs . 2002 QUALCOMM Incorporated 7-9 CDMA 120 - cdmaOne and CDMA2000 Concepts and Terminology 80-13321-1 X11 Section 7 Handoffs The Mobile Searches for Strong Pilot Signals The searching process is continuous and is conducted not only to find handoff candidates but also to identify usable multipath arrivals from the serving cell. The Mobile Reports The handoff process is mobile-assisted meaning that when the mobile detects a Pilot of sufficient strength it reports the event to the Base Station. The Base Station Directs When the Base Station receives a report from the mobile a handoff decision is made and directions are sent to the mobile to perform the handoff. 2002 QUALCOMM Incorporated 7-10 CDMA 120 - cdmaOne and CDMA2000 Concepts and Terminology 80-13321-1 X11 Section 7 Handoffs Pilot Sets Pilots are grouped into four sets which prioritize them and increase the efficiency of searching. The searching process is not standardized but generally Pilots are searched in the following order Active Set Pilot Channels associated with forward Traffic Channels currently assigned to the mobile. This is a search for additional multipaths of the same Pilot Channels. Candidate Set Pilot Channels whose strength as measured by the mobile exceeds a given threshold. Neighbor Set Pilot Channels transmitted by cells in the vicinity of the cells currently transmitting to the mobile. The contents of the Neighbor Set is normally configured by the system .