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CDMA Technology Overview February, 2001 - Page 4-1 CDMA Technology CDMA Technology Overview Overview Lesson 5 – Power Control, Registration, and Handoffs
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Page 1: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-1

CDMA Technology CDMA Technology OverviewOverview

Lesson 5 – Power Control, Registration, and Handoffs

Page 2: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-2

Power Control

Page 3: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-3

CDMA is an interference-limited system based on the number of users

Unlike AMPS/TDMA, CDMA has a soft capacity limit

Each user is a noise source on the shared channel

The noise contributed by users is cumulative

This creates a practical limit to how many users a system will sustain

Precise power control of the mobile stations is critical if we want to

Maximize system capacity

Increase battery life of the mobile stations

The goal is to keep each mobile station at the absolute minimum power level necessary to ensure acceptable service quality

Ideally the power received at the base station from each mobile station should be the same (minimum signal to interference)

Mobile stations which transmit excessive power increase interference to other mobile stations

CDMA Power Control

Page 4: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-4

Reverse Open Loop Power Control

• The mobile station makes a coarse initial estimation of the required transmitpower, based upon the total received power.

• Problems with Reverse Open Loop Power Control:

• Assumes same exact path loss in both directions; therefore, cannotaccount for asymmetrical path loss

• Estimates are based on total power received; therefore the power receivedfrom other cell sites by mobile station introduces inaccuracies

• The mobile station makes a coarse initial estimation of the required transmitpower, based upon the total received power.

• Problems with Reverse Open Loop Power Control:

• Assumes same exact path loss in both directions; therefore, cannotaccount for asymmetrical path loss

• Estimates are based on total power received; therefore the power receivedfrom other cell sites by mobile station introduces inaccuracies

BTSMobile

Reverse Open LoopPower Control

BTS

BTS

Page 5: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-5

Estimated Reverse Open LoopOutput Power

mean output power (dBm) = - mean power input (dBm)+ K+ NOM_PWR - 16 x NOM_PWR_EXT+ INIT_PWR

Power output level for the initial probe during open loop probing on the Access Channel (with closed loop correction inactive):

Subsequent probes in the sequence are sent at increased power levels(each probe is incremented by a value equal to the parameter PWR_STEP)

The “turn around constant” K is calculated assuminga nominal cell Effective Radiation Power (ERP) of 5 W

and a nominal cell loading of 50%.

Its value is -73 for cellular systems and -76 for PCS systems

Page 6: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-6

Estimated Reverse Open LoopOutput Power

Power output level for the initial transmission on the Reverse Traffic Channel:Power output level for the initial transmission on the Reverse Traffic Channel:

mean output power (dBm) = - mean power input (dBm)+ K+ NOM_PWR - 16 x NOM_PWR_EXT+ INIT_PWR+ the sum of all access probe corrections (dB)

Page 7: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-7

Reverse Closed Loop Power Control

• Compensates for asymmetries between the forward and reverse paths

• Consists of power up (0) and power down (1) commands sent to the mobilestations, based upon their signal strength, measured at the Base Station andcompared to a specified threshold (setpoint)

• Each command requests a 1dB increment or decrement of the mobilestation transmit power

• Transmitted 800 times per second, always at full power

• Allows to compensate for the effects of fast fading

Mobile BTS

Signal StrengthMeasurement

Setpoint

or

Reverse Closed LoopPower Control

Page 8: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-8

Power Output Estimations (Summary)

The mean input power is defined as the power received at the mobile station for the 1.25 MHz RF channel bandwidth being used

The access parameter values can vary between base stations

They accommodate differing forward power levels and antenna gains

They are specified in the Access Parameters Message, sent over the Paging channel

Open Loop Probing on the Access Channel

Reverse Traffic ChannelInitial transmission

After First Power ControlBit Has Been Received

Based on: 1. mean input power measured at mobile station2. access parameters provided by the base station

(Subsequent probes are adjusted by access parameters provided by the base station)

Based on:1. mean input power measured at mobile station2. access parameters provided by the base station3. sum of all the access probe adjustments

Based on:1. mean input power measured at mobile station2. access parameters provided by the base station3. sum of all the access probe adjustments4. sum of all the power control bits received

Page 9: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-9

Reverse Outer Loop Power Control

• Not part of IS-95A or J-STD-008.

• Most gradual form of reverse link error control

• Setpoint is varied according to the FER on the Reverse TrafficChannel (determined at the Base Station Controller)

• Sampled at a rate of 50 frames per second (20 ms / frame)

• Setpoint adjusted every 1-2 seconds

FER

Mobile BTS BSC

Reverse Outer Loop Power

Control

Signal StrengthMeasurement

Setpoint

or

Reverse Closed LoopPower Control

Page 10: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-10

Forward Traffic Channel Power Control

• The base station slowly decreases power to each mobile station

• As the FER (determined at the mobile station) increases, the mobilestation requests a Forward Traffic Channel power increase

FER

Mobile BTS BSC

Adjust Fwd.power

Forward Link Power Control

Page 11: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-11

Summary of All Power Control Mechanisms

• All types of power control work together to minimizes powerconsumption at the mobile stations, and increases the overall capacityof the system transmit power

FER FER

Mobile BTS BSC

Signal StrengthMeasurement

Setpoint

or

Adjust Fwd.power

Reverse Outer Loop Power

Control

Reverse Closed LoopPower Control

Forward Link Power Control

Reverse Open LoopPower Control

Page 12: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-12

Registration

Page 13: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-13

Roaming

A mobile station may be in any of the following roaming states: Home: mobile station is at its home location (not roaming) NID roaming: mobile station is within a foreign NID but in the home SID SID roaming: mobile station is within a foreign SID

A mobile station maintains a list of one or more “home pairs” These are SID/NID combinations defining the mobile station’s home

location They are stored in semi-permanent memory

The identity of current SID/NID is contained in the System Parameters Message (sent on the Paging Channel)

HomeSID/NID List

(2, 3)(2, 0)(3, 1)

SID = 2SID = 4

SID Roaming

NID = 7 NID =3NID = 0

NID Roaming Not RoamingRoaming Status

Page 14: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-14

HLR & VLR

Contains permanent subscriber data provisioning information service information features available to the

subscriber Contains dynamic information

mobile station’s current location Supports call routing Queried by the MTX when

subscriber information is needed, regardless of the mobile station’s current location

Stores a subset of the HLR information pertaining to the mobile stations currently registered in the VLR’s service area

HLR VLR

Page 15: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-15

CDMA Registration

Registration is the means by which a mobile station notifies the cellular system of its location, status, identification, and other characteristics

Balance is required between paging and registration

Infrequent registration results in a high rate of paging

Frequent registration places a high load on access channels

Proper system design allows a base station to efficiently page the mobile station when establishing a mobile-terminated call

Registration also provides

The mobile station’s SLOT_CYCLE_INDEX and SLOTTED_MODE

The mobile station class mark and protocol revision number so that the base station will know the mobile station’s capabilities

Two types of mobile registration

Non-Autonomous: explicitly requested by the base station, or implied based on other types of messages received by the mobile station

Autonomous: triggered by some event other than the reception of an explicit or implicit request from the base station

Page 16: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-16

Forms of CDMA Registration

Power-up registration

Power-down registration

Timer-based registration

Zone-based registration

Distance-based registration Parameter-change registration

Implicit registration

Ordered registration

Traffic channel registration

AutonomousRegistration

AutonomousRegistration

Registration Types NOTSupported by Nortel

Registration Types NOTSupported by Nortel

Non-AutonomousRegistration

Non-AutonomousRegistration

All types of registration can be enabled or disabled by means of the System Parameters Message

Page 17: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-17

Power-Up Registration

Mobile station registers when Directed to power-on by the user Switched to an alternate serving system Switched from using an analog system

Delays 20 seconds Preventing multiple registrations whenever power is quickly

turned on and off

ON

Access Channel

Page 18: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-18

Power-Down Registration

Mobile station registers when directed to power-down by the user Mobile station will not power down until attempt is completed Mobile station will not do power down registration if

Not registered in the current system Prevents unnecessary attempts to reach a user

Can be unreliable (v.gr., user powers down in garage)

OFF

Access Channel

Page 19: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-19

Timer-Based Registration

Mobile station registers when a timer expires Registration period is determined by the base station Allows system to de-register mobile stations that fail to register on

power-down

Access Channel

Page 20: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-20

Distance-Based Registration

Mobile Station MS registers whenever it does an “Idle Handoff” (handoff when not in a call) into a cell which lays outside a circle with REG_DIST radius and centered at the base station where MS last registered At position “a” MS registers with Base Station BS-1. BS-1 transmits its latitude and

longitude, and the REG_DIST parameter on its paging channel At position “b” MS does an idle handoff into BS-2 and reads the latitude and longitude

of this base station. MS then calculates the distance between BS-2 and BS-1, and if the result is less than REG_DIST it does not have to re-register

At position “c” MS is still listening to BS-2 (no need to re-register yet) At position “d” MS does an idle handoff into BS-3. MS reads the latitude and

longitude of BS-3 and calculates the distance between BS-3 and BS-1. As this distance exceeds REG_DIST, MS re-registers

a

b

cd

BS-1

BS-2

BS-3

REG_DIST Paging Channel Access Channel

Idle Handoff

Idle Handoff

Page 21: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-21

Zone-Based Registration

The mobile station registers when it enters a new zone A zone is a subset of the base stations within a network The mobile station keeps a list of the zones where it has registered, up to a

maximum determined by the base station Each zone is uniquely identified by the registration zone number parameter

(REG_ZONE) plus the SID and the NID to which it belongs The mobile station activates a timer for every zone where it has registered,

except the active one, and de-registers when the timer expires The mobile station will not re-register if it enters a zone which is already in its list

1 2

3

4 5

NOTE: These are registration zones, not TMSI zones!

Page 22: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-22

Parameter-Change Registration

The mobile station registers after it modifies any of the following parameters (stored in the mobile station): the preferred slot cycle index the slotted mode indicator the call termination enabled indicators

or the following capabilities supported by the mobile station: the band classes the power classes the rates the operating modes

Access Channel

SLOT_CYCLE_INDEXSLOTTED_MODE

MOB_TERM_HOMEetc.

SLOT_CYCLE_INDEXSLOTTED_MODE

MOB_TERM_HOMEetc.

Page 23: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-23

Implicit Registration

Occurs when the mobile station and base station exchange messages not directly related to registration Messaging conveys sufficient information to identify mobile

station and its location Considered successful whenever mobile station sends an

Origination Message or Page Response Message Compatible with AMPS and IS-54 methods Effectiveness considered adequate to preclude use of ordered

registration

Access Channel

Origination Message

Page 24: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-24

Ordered and Traffic Channel Registration

Ordered Registration Allows the base station to order a mobile station to register

mobile station can be idle or in an active call Traffic Channel Registration

Allows the base station to obtain registration information about a mobile station that has been assigned to a Traffic Channel

Information exchange occurs on the Traffic Channel Suggested use is on inter-system handoffs

Neither one is supported by Nortel’s CDMA system

Paging Channel Access Channel Forward Traffic Channel Reverse Traffic Channel

Registration Message

Traffic Channel Registration

Registration Request Order

Registration Request Order

Page 25: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-25

Handoffs

Page 26: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-26

What is Ec/Io?

Ec/Io

Measures the “strength” of the pilot

Foretells the readability of the associated traffic channels

Guides soft handoff decisions

Is digitally derived as the ratio of good to total energy seen by the search correlator at the desired PN offset

Never appears higher than Pilot’s percentage of serving cell’s transmitted energy

Can be degraded by strong RF from other cells, sectors

Can be degraded by noise

Ec/Io dB

-25 -15 -10 0

Ec

Io

Energy of desired pilot alone

Total energy received

Page 27: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-27

What’s In a Handset?

ReceiverRF SectionIF, Detector

TransmitterRF Section

Vocoder

Digital Rake Receiver

Traffic CorrelatorPN xxx Walsh xx

Traffic CorrelatorPN xxx Walsh xx

Traffic CorrelatorPN xxx Walsh xx

Pilot SearcherPN xxx Walsh 0

ViterbiDecoder

CPUDuplexer

TransmitterDigital Section

Long Code Gen.

Op

en L

oo

p Transmit Gain Adjust

Messages

Messages

Audio

Audio

Bit Packets

Symbols

SymbolsChips

RF

RF

AGC

Bit Packets

Page 28: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-28

CDMA Handoffs

Handoff is the process by which a mobile station maintains communications with the Mobile Services Switching Center (MSC/BSC), when traveling from the coverage area of one base station to that of another

While in theIdle State Idle Handoff

CDMA-to-CDMA Hard Handoff

Softer HandoffDuringa Call

Soft Handoff

CDMA-to-Analog Hard Handoff

Page 29: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-29

CDMA Soft Handoff Mechanics

CDMA soft handoff is driven by the handset Handset continuously checks available pilots Handset tells system pilots it currently sees System assigns sectors (up to 6 max.), tells handset Handset assigns its fingers accordingly All messages sent by dim-and-burst, no muting!

Each end of the link chooses what works best, on a frame-by-frame basis! Users are totally unaware of handoff

Handset Rake Receiver

RFPN Walsh

PN Walsh

PN Walsh

SearcherPN W=0

Voice,Data,

Messages

Pilot Ec/Io

BTS

BSCMTX

BTS

Sel.

Page 30: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-30

Softer Handoff

Each BTS sector has unique PN offset & pilot Handset will ask for whatever pilots it wants If multiple sectors of one BTS simultaneously serve a

handset, this is called Softer Handoff Handset is unaware, but softer handoff occurs in BTS

in a single channel element Handset can even use combination soft-softer handoff

on multiple BTS & sectors

Handset Rake Receiver

RF

PN Walsh

PN Walsh

PN Walsh

SearcherPN W=0

Voice,Data,

Messages

Pilot Ec/Io

BTS

BSCMTX

Sel.

Page 31: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-31

Overall Handoff Perspective

Soft & Softer Handoffs are the best but a handset can receive BTS/sectors

simultaneously only on one frequency all involved BTS/sectors must connect to a single

BSC (the BSC must choose packets each frame) must be same on all BTS/sectors

If above not possible, handoff still can occur but will be “hard” like AMPS/TDMA/GSM intersystem handoff: hard change-of-frequency handoff: hard CDMA-to-AMPS handoff: hard, no handback

auxiliary trigger mechanisms available

Page 32: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-32

CDMA-to-CDMA Hard Handoff

Between cells operating on different frequencies

Between cells with traffic channels whose frames are staggered differently

A(ƒ1)

MTX

BSC

PSTN

B(ƒ2)

A(1)

MTX

BSC

PSTN

B(2)

Page 33: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-33

CDMA-to-CDMA Hard Handoff

Between cells that could be on the same frequency and have the same frame alignment, but which are subordinated to different BSCs which are not interconnected. This type of hard handoff would become a soft handoff if the frames received

at both cells could be delivered quickly to the same BSC for comparison, by interconnecting both BSCs with a high-speed link (see Inter BSC Soft Handoff / Inter System Soft Handoff)

MTX

PSTN

BSC

MTX

BSC

BA

Page 34: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-34

Pilot Detection Trigger – CELL_PILOT_BEACON sectors

The mobile station has no knowledge of the “beacon sector” concept. As far as the mobile station is concerned,

a beacon sector is just the same as any other standard CDMA sector.

Handoff Trigger

CELL_STANDARD CELL_PILOT_BEACON

BTS BTS

This trigger utilizes the existing soft handoff algorithm in the mobile station to facilitate the hard handoff.

•Certain pilots in the region where hard handoff is desired are identified as CELL_PILOT_BEACON in the Pilot Database of the SBS Controller

•The cell on the left serves the mobile station on frequency f1

•The cell on the right operates in frequency f2 and has a Pilot Beacon Unit that generates a pilot on frequency f1 (or this pilot is generated by a standard CDMA cell of an adjacent system/market)

•As the mobile station travels into the region in which hard handoff is desired, soft handoff processing is initiated when the mobile station reports to the network that the signal of the beacon cell is received with sufficient strength

•SBS software determines that the reported pilot corresponds to a beacon cell, and hard handoff processing commences

Page 35: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-35

Hard Handoff using Beacon Pilot Sectors

ƒ1 ƒ1 ƒ2 ƒ2ƒ1

ƒ2 ƒ2

Beacon Sector on ƒ1

ƒ1 ƒ2

Beacon Sector on ƒ2

ƒ1

BEACON

BEACON

Page 36: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-36

Boundary Sector Trigger(“CELL_BORDER” Sectors)

This is a two-stage trigger which indirectly utilizes the existing soft handoff algorithm in the mobile station to facilitate the hard handoff

certain pilots in the region where hard handoff is desired are identified as “CELL_BORDER” in the Pilot Database of the SBS Controller

as the mobile station travels from left to right, it enters into handoff with both sectors and eventually ceases communication with the sector on the left (“CELL_STANDARD”)

when the active set contains only sectors datafilled as “CELL_BORDER,” the first-stage trigger is met and the second-stage trigger is enabled

the SBS starts monitoring the Round Trip Delay (RTD) of the signals between the mobile station and the base station from which it derives its time reference

when the RTD exceeds a certain threshold, the second-stage trigger is met and handoff processing continues with the target selection activity

The mobile station has no knowledge of the “border sector” concept. Asfar as the mobile station is concerned, a border sector is just the same asany other standard CDMA sector.

First-stage trigger

Second-stage trigger

CELL_STANDARD CELL_BORDER

RTDBTS

Page 37: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-37

Hard Handoff Using Border Sectors

ƒ1 ƒ1 ƒ2 ƒ2

ƒ1 ƒ1 ƒ2 ƒ2

Border Sector for ƒ1

Border Sector for ƒ2

Page 38: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-38

CDMA-to-Analog Handoff

The mobile station is directed from a forward traffic channel to an analog voice channel

Radio link continuity is not maintained Two types of handoff:

Inter-system - occurs while the mobile station is traveling into another system that has no CDMA service

Messaging will tell the mobile station to select AMPS Currently, the mobile station cannot handoff back from

AMPS to CDMA (until the end of the call, when the mobile station reacquires the system) because the necessary signaling messages not supported)

Intra-system - occurs while the mobile station is traveling within the system

Load balancing Improve voice quality No CDMA service

Page 39: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-39

Lesson Review

1. What is the purpose of power control?

To maximize system capacity by minimizing noise/interference, and to increase battery life in the mobile stations.

2. What is the ideal situation at the base station regarding power level of the received mobile station signals?

To receive exactly the same (minimum) power level from every mobile station.

3. Define CDMA registration and explain its purpose

CDMA registration is the means in which a mobile station notifies the cellular system of its location, status, identification and other characteristics. The purpose of CDMA registration is to allow the system to efficiently page the mobile station when establishing a mobile terminated call.

Page 40: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-40

Lesson Review

4. Name the forms of registration, indicating whether they are autonomous or not.

Autonomous:Power-up registration,Power-down registration,Timer-based registration,Distance-based registration, andZone-based registration.

Non-autonomous:Parameter-change registration, Implicit registration,

Ordered registration and Traffic Channel registration.

5. Identify the cases of CDMA handoff that can occur when the mobile station is in the Traffic Channel State.

Soft handoff, Softer handoff, CDMA-to-CDMA Hard Handoff, and CDMA-to-Analog Hard Handoff.

6. Identify the message sent by the mobile station to report the strength of the pilots it measures

Pilot Strength The Measurement Message.

Page 41: CDMA Technology OverviewFebruary, 2001 - Page 4-1 CDMA Technology Overview Lesson 5 – Power Control, Registration, and Handoffs.

CDMA Technology Overview February, 2001 - Page 4-41


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