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Confidential

CDMA BASICS

CALL FLOW IN CDMA

Performance Management Terminology (cont.)O

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Admission Connection Service

Blocked Call Setup Failure Dropped Call

Access Failure

HANDOFF IN CDMA

Handoff processWhen a MS is moving from one cell to another, the MS undergoes procedures, called handoff, that allow the MS to acquire the pilot channel transmitted by

neighboring BTS and to make another connection to a new BTS, while maintaining a connection to the old base station transceiver system (BTS).

To perform a handoff process, every MS measures and internally stores the information about neighboring Forward Pilot Channels (FPiChs) acquired in its current location.

Active setPilots of CDMA carriers whose forward paging channels of Forward Common Control Channels

(FCCChs) are being monitored while in idle state. During a call, these are the pilots associated with forward traffic channels assigned to the MS.

Candidate setPilots not currently in the active set but with enough signal power level to become an active pilot.

Neighbor setPilots that do not belong to the active or candidate sets but may also be considered candidates for a

handoff process

Remaining setAll remaining pilots that do not belong to any of the other sets but are in the area where the MS is

located;

Handoff Pilot Sets

Soft handoffA soft handoff is applied to an MS that starts communication with a new BTS while still

connected to another BTSMake-before-break

Hard handoffA MS is disconnected from one BTS and is switched to another

Break-before-makeSofter handoff

A special soft handoff between sectors in the same BTSIdle handoff

An idle handoff is performed while in idle state when the MS is moving from one BTS to another

Access handoffAn access handoff occurs in the system access state when the MS is performing access

attempts.

Handoff Types

FER is the most common network quality parameter to execute power control

Ec/Io (ratio of chip energy, Ec, to interference plus noise spectral density)

Eb/Io (ratio of bit energy, Eb, to interference plus noise spectral density)

Power control aims to quickly and efficiently estimate the minimum MS transmission power to achieve the required communication quality (based on

FER statistics)

Benefits of power control in CDMA systems

Increase in system capacity

Minimization of near-far effect

Increase in battery lifetime

Power Control

Open loop power control

Usually implemented as the initial power control to give an estimate of minimum transmission power used for access channels, such as Reverse Access Channels

(RAChs), Enhanced Access Channels (EAChs), and Reverse Common Control Channels (RCCChs), during system access state.

Closed loop power control

Usually implemented for traffic channels, which need a more sophisticated power control system. cdma2000 systems can also employ this type of power control

even during the system access state.

Procedure of the closed loop power control

A) An MS initially uses the transmission power defined in the last message from

last access probe transmitted on the system access state.

B) The BTS determines a ‘set point’ power level, which is considered ideal for

receiving signals within a certain QoS.

C)The set point is periodically adjusted.

D) The BTS performs power control by transmitting power control bits, which

instruct MSs individually to increase or reduce transmission power according to

the estimated set point value.

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