antenna selection
TRANSCRIPT
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The only time a Tata Indicom Phone wont be accessible.
Please switch off your mobile phones during the presentation.
Confidential
CDM B SICS
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C LL FLOW IN CDM
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Performance Management Terminology (cont.)
OriginationMessageTxfro
mMS
or
G
eneralPageTxfromB
S
O
riginationMessageRx
atBS
or
PageResponseRxat
BS
ChannelAssignmentMe
ssage
TxfromBS
ServiceConnectCom
plete
MessageRxatB
S
CallConnectivit
yLost
Admission Connection Service
Blocked Call Setup Failure Dropped Call
Access Failure
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H NDOFF IN CDM
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Handoff process
When 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.
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Active set
Pilots 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 set
Pilots not currently in the active set but with enough signal power level to become an active pilot.
Neighbor set
Pilots that do not belong to the active or candidate sets but may also be considered candidates for ahandoff process
Remaining set
All 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
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Soft handoff
A soft handoff is applied to an MS that starts communication with a new BTS while still
connected to another BTSMake-before-break
Hard handoff
A MS is disconnected from one BTS and is switched to another
Break-before-make
Softer handoffA special soft handoff between sectors in the same BTS
Idle 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
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FERis 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
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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.
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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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TH NK YOU