Evdo Presentation

7/30/2019 Evdo Presentation

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1XEV-DO THE NEXT GEN

WIRELESS DATA

CHANGE IN TURBOCODER:

========================The 3G technology introduces a turbo coder that can be used as a half-, third-,fourth-, and fifth-rate coder. On average, a turbo coder effectively reduces theminimum required Eb/No by 1 dB to 2dB. Without a turbo coder, the exponentialcomplexity for a K = 10 coder, which would be required for a fourth-and fifth-ratecoder, does not offset its Eb/No benefits. This design complexity is minimizedwith a turbo coder. In 1xEV-DO, the turbo coder is operated at a third- and fifthratein the forward link, and at a half- and fourth-rate in the reverse link.

A turbo coder consists of two K = 4 half-rate convolution coders and a turbointerleaver, as shown in Figure 1. Every information bit is routed through theturbo coder unchanged to become one of the coder output symbol bits. Theinformation bit is also coded by the K = 4 half-rate coder, producing twosymbol bits on lines A and B. The K = 4 half-rate coder is not as complex as

the K = 9 coder, and its output is a function of the previous three bits. Inaddition, the input information bits are scrambled by the turbo interleaverand are coded by the interleaver K = 4 half-rate coder, producing twoaddition symbol bits on lines C and D.The coder rate selection is implemented through the puncture control.When a half-rate coding is selected, the puncture control inhibits the bitstreams on lines B, C, and D. Thus, the turbo coder generates only twocoded symbol bits: the original instruction bits and the bits on line A. Whenthird-rate coding is required, the 2-bit symbol output of the K = 4 half-ratecoder is enabled along with the original information. When fourth-rate


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coding is required, in addition to the 2-bit symbol at the output of the K = 4half-rate coder and the original information bit, the bit stream on line C isenabled.

EVDO BASIC STATEMENTS

1> What is the coding .. is it still CDMA?Rather than allowing multiple users tosimultaneously share a single carrier for both uplink and downlinktransmission, CDMA2000 1xEV-DO uses a different approach to achievehigh data rates. 1xEV-DO recognizes the asymmetrical nature in which datais moved over an IP network. Higher volumes of data are downloaded fromthe network to the user than are uploaded from the user to the network. Thedownload to upload ratio may vary between four-to-one and six-to-one, andis in some cases even higher. To take advantage of this asymmetricalpattern, 1xEV-DO technology uses different multiple access divisiontechniques for uplink and downlink data transmission. For uplink datatransmission, 1xEV-DO uses the classical CDMA code division technologysimilar to IS-95 and 3G-1X, and for downlink transmission, a time divisiontechniques where, a single 1.25-MHz carrier is time-shared with amaximum of 59 users, is used. Because voice transmission requirescontinuous use of the carrier, voice transmission is not implemented in1xEV-DO

2> How about the hardware philosophy?While the Physical Layer of 1xEV-DO, identifying channel encoding andchannel structure differs greatly from IS-95 and 3G-1X, the RF signal and1.25-MHz bandwidth is compatible with IS-95. Therefore, the same RFequipment (amplifiers, filters, etc.) used to provide IS-95 service can beused to provide 1xEV-DO service.


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3> How we are able to reach such high data rate?The elimination of uninterrupted, real-time voice transmission constrains allows1xEV-DO systems to time-multiplex the distribution of downlink data to each onlinesubscriber in a particular service area.Unlike IS-95 and 3G-1X systems, where the base station must be able to

maintain simultaneous, continuous downlink voice channels within a sector, timemultiplexing allows 1xEV-DO systems to concentrate its full downlink transmitpower to a single on-line user at any one time. This allows the base station totransmit user data at the highest data rate, up to 2.4-Mbps peak data rateprovided, that a discernible Eb/No level is maintained.

4> Can it coexist?The 1xEV-DO architecture provides an overlay solution to voice networksrunning in cellular or personal communications services (PCS) spectrums andrequires a dedicated 1.25-MHz channel. Although designed to leverage from IS-95 and 3G-1X systems, the 1xEV-DO does not require anysignaling or backhaul interaction with the MSC and can co-exist with any voicetechnology such as GSM and TDMA

5> Characteristics?The peak data rates for 1xEV-DO are: Forward Link (Downlink) = 2, 457.6 Kbps Reverse Link (Uplink) =153.6 Kbps.Forward link average aggregate throughput can be from 350 to 550 kbpsper carrier-sector for high mobility (vehicle) end-users, and up to 650 kbpsper carrier-sector for low-mobility and stationary end-users.

6> How are the data rates controlled on the FORWARD LINK?

Data rate is assigned based on the signal strength measured at the AT.The data rate that is actually transmitted to any one AT is a function of that

AT RF environment. The AT continuously monitors the quality of its receivepilot signal, in addition to monitoring the pilot signal from other neighboringsectors. As with IS-95 and 3G-1X, the pilot signal transmitted by eachsector is distinguished by an offset of the PN short code. Because thereceived pilot signals from the different sectors are predictable, the AT canacquire the pilot signal and measure the pilot channel carrier-to-interference(C/I) ratio. By measuring the C/I ratio, the AT is able to determine its current bestserving sector and the highest data rate it may be able to receive reliable datafrom that sector. As a result of this determination, the AT sends back a data ratecontrol (DRC) report to the BTS. The DRC identifies the serving sector and thehighest rate in which the AT can receive quality data from the sector. The servingsector transmits to a scheduled AT at the rate indicated in its DRC report

As shown in Table 1-2 forward link data can be transmitted at nine different datarates that are chosen to provide efficient coverage under a full range ofconditions experienced at typical cellular/PCS cell sites. The data starts at 38.4kbps and doubles itself up to 2.457.6 kbps. Each data rate is associated with aparticular packet bit size and modulation type.


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7> How are the PACKETIZED DATA transmitted on the FWD link?

Forward link data is transmitted in successive 26.67-ms frames, which aredivided into sixteen 1.667-ms slots in which packets of data are transmitted. The transmission duration of a single packet may vary from 1 to 16slots as a function of the data transmission rate. Pilot and control information are inserted (punctured) within eachframe at fixed intervals for AT extraction. The packet AT destination is specified within the packet. Upon receiving the packet, the AT transmits an acknowledge (ACK)signal indicating that the packet is received and its data isuncorrupted.

8> How are the data rates controlled on the REVERSE LINK?

Same as in 3G-1X, 1xEV-DO uses reverse link (uplink) pilot pulses permitting coherentdetection by the BTS of the reverse link data from the AT. Uplink data istransmitted in successive 26.67-ms frames at data rates from 9.6 kbps to 153.6kbps. The initial transmit rate of an AT is 9.6 kbps. Subsequently, the transmitrate can be increased or decreased depending on the total traffic activity in

the sector. A Reverse Rate Indicator (RRI) transmitted by the AT is used bythe BTS to identify the rate in which the AT is transmitting traffic data.

9> What is the capacity of 1X-EVDO system?

Because of the fundamentaldifferences in how the reverse and forward links operate, capacity analysis forthe two links is completely different. The reverse link is analyzed in a methodsimilar to voice systems and results in a maximum number of simultaneoususers. The forward link is analyzed in a manner more similar to 3G-1X dataservices, and results in per-sector throughput.


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THE REVERSE LINK CAPACITY:


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As shown in the above table, the capacity in terms of the maximum number ofsessions is almost independent of data rate. The higher data rates requirehigher traffic gain. The resulting extra power is offset by the decrease in theamount of time the channel is used (i.e., channel activity). The capacity for the153.6 kbps channel users is lower because of the higher required Ec/Nt.

THE FORWARD LINK CAPACITY:


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As can be seen from the above figure, the throughput increases with the number ofusers, leveling off at around eight users. This increase in users is a directmanifestation of the scheduling gain. As the scheduler has moreusers to choose from, there is a greater probability that one or more of the users willbe in a good Geometry and capable of supporting high channel rates.

1X EV-DO RAN ARCHITCTURE


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What are the functions of each elements of the architecture?

AT:Users will access the system, which is referred to as the Radio AccessNetwork (RAN), through an Access Terminal (AT) that maintains an air

interface with a 1xEV-DO base station. The AT may be used in a laptopcomputer, a hand-held device such a Palm Pilot or personal digital assistant, ormulti-mode mobile with AMPS/IS-95 and 3G-1X/1xEV-DO capabilities.

BTS:All call processing negotiated between the AT and thebase station is covered is defined by 1xEV-DO Protocol

Architecture IS-856


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FMS:

The FMS provides the interface to complete the call controlfunctions required by the AT to acquire the RAN network. This interface isdefined by the 1xEV-DO IS-856 Protocol Architecture.

Two network routers are physically housed with an FMS in the same frame.The routers shown in above figure are functionally located and do not necessarilyrepresent individual routers.

The RAN network may contain up to six FMS frames, designated FMS0through FMS5. The FMS frame houses up to four primary and four backup AServers. Each A-Server contains one Application Processor (AP) running onthe Sun Solaris Operating System (OS), Version 8. The A Server also containsup to two Traffic Processors (TPs), one Alarm Card, and one local boot disk.The APs run the 1xEV Controller software to perform overhead channelmanagement signaling processing and OA&M control functions. Thesefunctions include session establishment and release, frame selection, andradio link protocol (RLP) processing. The TPs run VxWorks to perform traffic

processing and the Packet Control Function (PCF) to handle the packet datainterface between the base station the PDSN components.

The 1xEV controller software also performs the packet control function (PCF)to process the data for standard A10/A11, Radio-Packet (R-P) interface withthe Packet Data Serving Node (PDSN). This interface is maintained either via a 100Mbps ethernet connection or an ATM interface to the Internet service providerbackbone IP network. The A10/A11 R-P interface terminates the mobilitymanagement defined by the air interface protocol (IS-856) and is the demarcationpoint between the RAN and IP packet networks. The FMS-processed data isconnected to PDSN via the downlink input router, and because the PDSN is locatedat Internet serving network, the router is connected to the PDSN over an ethernetconnection.

Each FMS frame is capable of interfacing and handling the call processing functionfor 48 base stations.

PDSN:

Pdsn implements the PPP,IP and the STATIC IP layer of the EV-DO protocol stack.

It also manages the IP address .Let us understand that.

The PDSN is operated as a Home Agent (HA) for the serving network in which it

Resides. The serving network allocates the PDSN to open an IP sessionwith a petitioning AT. The IP address defines a physical location on the Internet.When an IP session is established with an AT, the most significant digits of the IPaddress, which are listed in the Internet routing tables, are used to direct Internetdata traffic associated with the AT to and from the PDSN. The PDSN maps the AT tothe IP address so that data reaching the PDSN is directed to the AT.

AAA:


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Authentication,

Authorization and

Accounting :Prior to allowing an AT network access, the AT is challenged for authenticationto determine if the AT is not masquerading under a false ID, and also forauthorization to determine if the AT is permitted (authorized) to access the

network. This challenge is implemented by the Authentication, Authorizationand Accounting (AAA) server via a server/client relationship with the PDNSclient. The AAA maintains a subscriber database which is used to validate theusers ID and password. The PDSN records AT data usage to provideaccounting information to the AAA Server.

The protocol stack?

The most important point of this stack??? the RLPThe RLP connection between the AT and the FMS has negative acknowledgement(NACK) capabilities, indicating when missing frames are discovered. This NACKcapability, which reduces the amount of signaling required, allows for the


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retransmission of frames that were lost. While this capability will not totally eliminatelost frames, it will significantly decrease the probability of incurring lost frames. Ifframes are lost anyway, a high-level protocol or mechanism, such as TCP shouldrecover from that problem as it does now in wire Internet connections.

LETS UNDERSTAND THE AIR INTERFACE:

FWD LINK:

Each active user is assigned one of 59 Walsh codes from a 64-ary set, where fourcodes are pre-assigned. Therefore, a single carrier can be time-shared by 59 activedata traffic channel users. This means that although at any one time, only one useris actively receiving data over the data traffic channel, 59 users are assigned logicalchannels on the carrier.


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The frame structure:

This is what happens when the AT is active and data is being downloaded


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When no data is transmitted the idle slot looks like

Even thoughdata is not transmitted during idle time slots, the MAC and pilot channels are

transmitted during their correct timing sequence within the idle time slot. The forwardMAC Channel is composed of up to 64 code channels, which are orthogonallycovered and BPSK-modulated on a particular phase of the carrier. Each codechannel is identified by a MAC index, which has a value of between 2 and 63 anddefines a unique 64-ary Walsh cover and a unique modulation phase. There are twosub-channels on the forward link MAC channel: the Reverse Activity Channel (RAC)and the Reverse Power Control Channel (RPC).

SO THAT EXPLAINS THE CONTROL CHANNEL BUT HOW IS THE DATA TRAFFICCHANNEL IS MAPPED ON THE FWD LINK?

User data is transmitted in two 400-chip bursts during each half slot period. Inorder to maximize data throughput, AT users sharing the carrier are serviced in

any time slot order. Depending on the scheduler algorithm, AT users withreporting a good RF environment will have a better chance to be allotted the timeslot to receive data. Other AT users will have to wait until their RF environmentimproves. In this way, the base station is always transmitting at the highest ratepossible to maximize its data throughput.

Two very important concepts:

DRC (Dynamic Rate Control)The rate at which data is transmitted to the AT is a function of the AT RFenvironment, and is subject to dynamic reselection during each 1.66-ms slot-clockperiod. The AT continuously monitors the quality of receive pilot pulses from allsectors in the active set (all neighboring sectors). In response, the AT sends back adata rate control (DRC) report to the base stations in the active set. The DRC reportidentifies the sector with the highest C/I ratio and the highest rate in which the ATcan receive quality data from the sector within a margin to insure a low erasure rate.The sector identified be the DRC code than resumes transmission at the rateindicated by the DRC report.


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Virtual Soft HandoffThe selection from one sector to another is called virtual soft handoff. Unlike softhandoff performed in IS-95 during which the mobile may simultaneously interact withtwo or more sectors to realize a signal gain, this signal gain is not achieved duringvirtual handoff because the AT interacts with only one sector at a time.Lets understand it through a call flow.

When the DRC report from an active AT identifies (points to) Sector 1 as its bestserving sector, Sector 1 sends a Forward Data Request to the 1xEV Controller inthe FMS. In response, the FMS sends the requested Data Packets to Sector 1,which are then transmitted in Frame messages to the AT. Subsequently, if theDRC reports from the AT point to Sector 2 as its best serving sector for a definableperiod, Sector 2 will send a Forward Data Request to the 1xEV Controller in theFMS. Sensing that it has not received best server pointing DRC reports for aperiod of time, Sector 1 will send a Forward Stop Indicator message to the 1xEVController. This message also identifies the last frame ID transmitter to the AT.

After receiving indications from both sectors, the 1xEV Controller directs Sector 1to flush the remaining un-transmitted data from its buffer. The Data Packets arethen sent to Sector 2 so that transmission to the AT can continue from Sector 2


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HARDWARE ELEMENTS OF LUCENT EV-DO

BTS:

Whether EVDO carriers can be added to the existing MODCELL

cabinet?

YES

For MODCELL3.0

A 1xEV-DO/IS-95/3G-1X mixed-mode Modular Cell 3 cabinetwill support a mix of 1xEV-DO and IS-95 and/or 3G-1X carriers by allowing themixing of 1xEV-DO CDMA Digital Module (CDM) with IS-95 and 3G-1X CDM in thesame cabinet. Because 1xEV-DO technology uses the same RF footprint as doesIS-95 and 3G-1X, the top portion of the cabinet, containing filters, transmitamplifiers, and other components does not change for 1xEV-DO. The only hardwaremodification required for 1xEV-DO deployment is within the top shelf of the CDM..

There is no limitation on the placement of 1xEV-DO carrier. This means that the 1xEV-DO carriercan be equipped in any CDM ofthe Modular Cell frames, primary frame, or growth frame.The 1xEV-DO Modem contains the functionality required to support the 1xEV-DOphysical layer and is used for all 1xEV-DO Flexent platforms. Currently, only one1xEV-DO carrier can be deployed per Modular Cell cabinet by modifying the first CDM.

Converting the CDM hardware for1xEV-DO deployment is a two-step procedure:a. All CCU packs are removed and replaced with a single 1xEV-DOModem (EVM). The EVM contains two modem boards, EVTx and EVRx.Two CCU slots are reserved for a single EVM, where the EVTx transmitboard is plugged in to slot 1 and the EVRx receive board is plugged in toslot 2. The 1xEV-DO modem boards are pin-compatible with thebackplane so that no external wiring or pin jumping is required.b. The CRC must be replaced with a 44WW13D or later version. Thisversion accommodates 1xEV-DO operation and is compatible with IS-95and 3G-1X.


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MODCELL 4.0

Rather than having dedicated CDMs to separately process each carrier as in theModular Cells 1, 2, and 3, the digital shelf in the Modular Cell 4 cabinet pools itscarrier signal processing hardware resources for either 1xEV-DO data or 3G-1X/IS-95 data. Universal radio controllers (URC) are used to steer transmit and receivedata for each carrier to either an EVM for 1xEV-DO operation or a CDMA modemunit (CMU) for IS-95 and 3G-1X (refer to Figure 4-5). In a mixed-mode system, atleast two URCs are required, one for 1xEV-DO data and the other for 3G-1X/IS-95

data. For transmission, the URC will direct the signal received from the RNC orAUTOPLEX network to either the 4.0 EVM, for 1xEV-DO, or CMU for 3G-1X and IS-95, where the signal is modulated. In large cells, a number of CMUs may beinstalled to provide a pool of channel elements (CE) to process 3G-1X/IS-95 voiceand datasignals. The task of the URC is to select the next available CMU andCE from the pool to process the incoming voice and data signals.


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The modulated signal from the 4.0 EVM or CMU is up-converted to itsappropriated carrier frequency by the UCR. The upconverted carrier signal isthen amplified, filtered and routed to the base station transmit antenna. EachUCR can process up to three carriers.Reverse link signals received through the UCR are down-converted andappropriately routed to either the 4.0 EVM or the next available CMUdesignated by the URC for demodulation. The demodulated signal is thenrouted through its appropriate URC to its designation via the RAN or

AUTOPLEX network.

The location:

The digital card shelf backplane is functionally divided into foursections, where each section is dedicated to receive circuit packs of a specifictype. Except for the first section, which is dedicated for URC, circuit packs maybe placed in any slot within their dedicated sections.The first section is a fourslotlocation where URCs can be placed in the first three slots. The fourth slotis reserved for a redundant URC that will be available in a future release. TheURC provides T1/E1 facility interface via the I/O unit (IOU) for the digital cardshelf .Initially, in a mix-mode system, one URC must be usedexclusively for 1xEV-DO service. The URC exclusivity will be removed insubsequent releases.

The second section is divided into two six-slot groupings, where the first group isimmediately after the URC section, occupying slots 5 through 10, and the secondgroup is the last six slots on the digital shelf, occupying slots 17 through 22.Generally, the first two of the 12 slots are occupied the 4.0 EVM EVTx and EVRxmodem boards and the remaining slots may be occupied by CDMA modem units(CMU) in base stations that also provide IS-95 or 3G-1X service. The CMUscontains a number of the channel elements (CE) that perform the signal spreadingand de-spreading required by CDMA baseband processing for IS-95 and 3G-1X.The third section is a two-slot position occupied by the common timing unit (CTU).


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The CTU receives the timing signal from the GPS to maintain base stationsynchronization with the other base stations in the CDMA network. Two CTU aregenerally installed where the second CTU provides backup. Lastly, the fourthsection is a six-slot position to be occupied by Universal CDMA Radio (UCR). TheUCR provides radio processing including peak limiting, overload control, andupbanding/downbanding for the appropriate RF frequency.

FMS


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The FMS requires a minimum of a primary and a backup DO-AP. Each DO-APconsists of the following


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One hard disk drive to provide a local boot disk One Sun Ultra SparcTM Central Processing Unit (CPU) card running theSolaris 9 operating system. Essentially, the CPU functions as the 1xEVDOapplication processor to perform Overhead Channel Managementsignaling processing and OA&M control functions. Two Traffic Processes (TPs) that run on the VxWorks operating systemto perform signaling and traffic processing One alarm card: Support for reset, power up, and power down commands issued fromthe Watchdog Integrated with the Modular Filter and Fusing Unit (MFFU) to providealarm indication such as temperature, power, and fan failures, inaddition to providing alarms for its associated server One Maintenance Interface Panel (MIP); allows connection of links tothe Local Maintenance Terminal (LMT) and external routercomponents.

Two routers (Ethernet switches) are provided, one switch is active, and theother is on standby. The router provides the physical and logical

communication data links between the network base stations and thecomponents within the FMS, and also provides the network links between theFMS components and the Packet Data Serving Node (PDSN) via 100baseT(Ethernet) interface specified for the R-P interface (also known as IOS A10-

A11 interface). The router also provides a data link between the ElementManagement System (EMS) on the OMP-FX, and to other servers within theFMS.


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EVDO CALL PROCESSING:

The AT and the RAN network maintain either a closed or open connection state thatdictates the type of communications between the two. Closed Connection: In this connection state, the AT is not assigned toa dedicated airlink resource. Communications between the AT and theRAN network are conducted over the access channel and controlchannel. Open Connection: In this connection state, the AT can be assignedthe forward traffic channel, and is assigned a reverse power controlchannel and a reverse traffic channel. Communications between the ATand RAN network are conducted over these assigned channels, as wellas over the control channel.

AT INITIALIZATION STATE:

In this mode, the AT registers on the RAN to identify its presence and locationwithin the RAN network. In response to registering, the AT is assigned a unique

address allowing the RAN to page and send messages to the AT.The AT will enter the initialization state, which is controlled by the initializationprotocol. In this state, the AT, which has no information about the serving basestation or RAN network, must acquire the RAN network and synchronize withits timing. The initialization state is activated by the air link managementprotocol after the AT is switched on or, the AT user attempts to open or returnto a session after a long pause. In either situation, the initialization state isactivated to control how the AT acquires the RAN network in its service area.To do this, the AT may select a forward CDMA channel from a preferredchannel record provided to the AT from the RAN network. In addition topreferred channels, the channel record identifies the system (compliancespecification) and its band class. Immediately after the AT is activated, the ATenters a RAN network determination mode.

At thistime, the AT selects and tunes to one of the channels from its channel recordand attempts to acquire its forward link pilot signal. If the AT cannot acquire thepilot signal within 60 seconds, the AT refers back to the channel record toidentify another network.When a pilot signal is acquired, the AT monitors the Sync Message broadcaston its control channel. The Sync message will contain information about itsserving base station and RAN. One of the values read from the Syncmessageis the range of AT revisions compatible with the base station, the base stationsector pilot PN offset, and network system timing. The RAN network sets theSystem Time field of the Syncmessage to 60 ms after the start of the ControlChannel Cycle in which the SyncMessage is transmitted. The System Time is

specified in units of 26.66 ms. The Syncmessage transmission period is 1.28seconds. If the AT acquires the Syncmessage within 5 seconds, the AT willadvance to the idle state. If the AT version is not within the revision rangespecified by the Syncmessage or the AT cannot synchronize to the controlchannel cycle within 5 seconds, the AT goes back to the RAN networkdetermination mode for channel reselection.

AT IDLE STATE:At this time, an open connection exists,where the AT is not assigned to a dedicated airlink resource. Communications


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between the AT and RAN network are conducted over the access channel andcontrol channel. In order for the RAN network to identify each AT that enters itscoverage area, the AT must register when it enters the coverage area.

Unlike IS-95 and 3G-1X, there is no central database such as a home locationregister (HLR) and visitor location register (VLR) in the in the 1xEV-DO systemas in traditional wireless voice systems to keep track of each AT location. Inorder to keep track of the AT and to know where to page it, 1xEV-DO usesregistration. There are two possible registration procedures: UATIRequestMessage-based RouteUpdate Message-based.In both messages, which are handled by the route update protocol, the ATsends its location information to the base station so that the RAN network mayfocus its paging of the AT to the correct coverage area. Rather than using serialnumber paging as in voice wireless systems, each AT is assigned a unicast ATidentifier (UATI) address. This address is similar to the IP address that isassigned to data packets to steer the packet

The AT must include its UATI address within the UATIRequestmessage to allow the

RAN to direct (address) its page to the AT. As a result, the RAN returns an accessacknowledge (AcAck) response. When the UATIRequestmessage is sent for thefirst time after the initialization state, the AT is not assigned any identificationaddress. To provide an address, the AT picks a Random Access Terminal Identifier(RATI) and includes the RATI in its UATIRequestmessage in place of the UATI. TheRAN recognizes the RATI and will assign a UATI value which the AT will usethroughout its stay within the subnet.The UATI is a 128-bitaddress value divided into two fields: UATI104 and UATI024. The 104 mostsignificant bits (MSB) of the UATI, which make the UATI104 field, provide datasteering within the RAN network between the PDSN and the base station sector,where the eight least significant bits (LSB) of the UATI104 field are the base stationsector codes. The UATI104 value is sent to the AT in the SectorParameterMessage

on the control channel. The least significant UATI024 field is sent to the AT in theUATIAssignmentmessage.

When an UATI value is included in the UATIRequestmessage, the RAN would knowthat the AT had registered in another subnet and is registering its location in itscurrent subnet. This reregistration is referred to as Inter-Subnet Idle Transfer. Inter-Subnet Idle Transfer is also known as Inter-PCF Idle Handoff.

When is Route Update Message sent ?In the idle state, the AT sends a RouteUpdate message to the RAN when the ATmoves into a different subnet. A subnet is a definable coverage area controlledthrough a single Evolution Controller (EVC) within a Flexent Mobility Server (FMS).The current subnet servicing an AT is identified by its Color Code sent over the

Control Channel. The RouteUpdate message is also sent when the AT computesthat its distance (radius, r) from the base station it sent last RouteUpdate message isgreater than the RouteUdateRadius value in the SectorParametermessage fromthat base station


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Where,xCandxL are the longitude and latitude, respectively, of the sector that

receive the last RouteUpdate message from the AT, andyCandyL are the longitudeand latitude, respectively, of the sector currently providing coverage to the AT. Thebase station locations are entered in the EMS data base via the Base Station

Antenna Longitude and Latitude in Degrees, Hours, and Seconds fields of theService Nodes GUI page for each base station. The RouteUpdate message is usedwhen the AT is requesting a traffic channel assignment

THE SLEEP SUBSTATE:

When the AT is in the sleep sub-state, it enters the slotted mode operation. Inthis mode of operation, the AT may stop monitoring the control channel andshut down some processing resources to reduce power consumption, andthereby increase battery life. The control channel, which is interlaced with thetransmission of traffic data, is transmitted every 425 ms for a 13.33-msduration, as shown in Figure . On the occurrence of every twelfth controlchannel cycle (time slot) which occurs every 5.12 seconds, the RAN and ATtransition from the Sleep Sub-State to the Monitor Sub-State for the 13.33-mscontrol channel cycle time slot to exchange synchronous capsules. To preventloss of this exchange, the AT cannot change its Active Set pilot at a time thatcauses it to miss a synchronous Control Channel capsule. There are 12 controlchannel cycles within 5.12 seconds


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The control cycle time slot used is derived from the ATs UATI value. The SleepState is similar to the 3G-1X slotted mode, and although 3G-1X has fewer timeslots, its slot cycle occurs every 5.12 seconds, allowing hybrid AT/3G-1Xmobile operation. If the AT is a hybrid mobile, it is required to monitor thepaging channel on the 3G-1X system as well as the 1xEV-DO slotted controlchannel in the same time slot period. Usually in 1xEV-DO, the sleep cycle timeslot is determined by the hash function using the AT-assigned UATI value. Ifthe 1xEV-DO control channel time slot assigned to the AT does not align withthe 3G-1X paging channel time slot, the AT is required to change the 1xEVDO-assigned time slot to coincide with the 3G-1X time slot. In that case, the ATwould send a PreferredControl Channel Cycle to the 1xEV-DO base station,indicating the desired time slot. As a result, the 1xEV-DO awake controlchannel time slot for the AT is recalculated to coincide with the 3G-1X awaketime slot.

HANDOFFFWD LINK HANDOFF:Forward link handoff in 1xEV-DO is directed by the AT when it is determined that aparticular sector could provide better service, in the way of faster data rate, than itscurrent serving sector. Upon monitoring pilot signal strength from the better servingsector, the AT calculates the highest data rate that can be supported from the sector.Then the AT identifies this rate in its transmitted data rate control (RDC) channel,which it directs to the sector. However, before doing this, the AT must be certain thatits target sector has the air resources to serve the AT, and that the sector can quicklytap into the ATs forward link data stream so to avoid unnecessary delay. To providethis certainty, the AT must continuously monitor the pilot signal levels from all of its

neighboring sectors, and choose those pilot PN offsets that are strong enough to bepotential candidates for handoff. When potential candidates are identified, the RANis informed via a message exchange that transpires between than. As a result, theEvolutionary Controller (EVC) in the RAN allocates traffic channels and thenecessary resources to the target sector so that it could handle the handoff shouldthe AT direct it to do so.

The Flexent Mobility Server (FMS) contains four primary EVCs and four backupEVCs. The data traffic handled by each on-line EVC is connected to the Packet DataService Node (PDSD) through the Pack Control Function (PCF). Each EVC servicesa single subnet which consists of up to eight base stations. A call handoff from asector serviced by the PCF in one subnet to a sector serviced by a different PCF in

another subnet, regardless of whether the PCF is on the same or different FMSframe, is called an inter-PCF handoff. This handoff will always be controlled by asingle EVC.

REVERSE LINK HAND OFF:Although in IS-95 forward and reverse link soft handoff occur simultaneously, in1xEV-DO soft or softer handoff only applies to the reverse link, and the mechanismin which soft and softer handoffs are implemented are similar. Soft and softerhandoffs are permitted in CDMA if the handoff sectors are operating on the same


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channel frequency currently in use by the mobile. In a typical soft handoff scenario,the mobile establishes communication with a new antenna face, on the same sectorof a new sector without breaking the connection with its current antenna face. Thisdiversity with two or more antenna faces will occur throughout the handoff period,which is the period that the mobile remains in the area to received discernible datafrom the antenna faces within the soft handoff theater (overlapping boundariesamong the antenna faces).In 1xEV-DO, reverse link handoff may occur when the AT directs its DRC channel toa new antenna face, prompting a reverse link soft handoff scenario between thecurrent antenna face and the handoff candidate antenna face. Duplicate datapackets received by the RAN from the soft handoff diversity are discarded by theRadio Link Protocol (RLP) operating at the airlink Application Lay. The RLP performsframe selection on the reverse link. When an AT is in soft handoff, all the reverse linklegs will send frames to the RLP. When the RLP receives multiple copies of thesame frame, the RLP selects a frame that successfully passes the CRC (CyclicRedundancy Check). Other copies of that frame are discarded.For open connections in soft handoff with sectors that are controlled by the same orby a different FMS frame, the same EVC always controls the connection. Thecontrol can be changed only when the AT re-registers with a new EVC under adifferent FMS. Re-registering occurs only when the AT is in the dormant mode.

During softer handoff, which occurs when handoff is between antenna faces on thesame, the same forward link and reverse link modems are used. The power controlbits for the softer handoff legs are combined. In other words, the modem makes onedecision for the up or down power control bits sent on the forward link power controlchannel.

HANDOFF BETWEEN 1XEV-DOAND 3G-1X:A hybrid AT supports both 1xEV-DO and 3G-1X calls and is capable oftransmitting and receiving data on the 1xEV-DO carrier and making voice calls,and transmitting and receiving data on the IS-2000 system.The frequency change between the 1xEV-DO system and the 3G-1X system isperformed by the hybrid AT. There is no network involvement at all; in fact, thenetwork is not aware of any switch.For example, if a hybrid AT is in the middle of transmitting data on the 1xEVDOsystem, when the AT receives a page for a voice call, the AT could switchto the 3G-1X system to receive the voice call if the user chooses to do so. The1xEV-DO system would not know that the AT had left the 1xEV-DO system and

gone to the 3G-1X system for a voice call, because the AT does not send anyindication back the 1xEV-DO system. The 1xEV-DO system would finallydetermine that the reverse link is lost or that the Dormancy Timer has expired;the 1xEV-DO system would release the connection. The 3G-1X system wouldnot know that the AT has just broken a connection with the 1xEV-DO systemfor this voice call.The hybrid AT is able to receive a Page message when it is on the 1xEV-DOsystem because the AT is in slot-mode operation with the 3G-1X network. The

AT will wake up in its designated 3G-1X slot to monitor the 3G-1X paging


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channel. If the AT is on the 1xEV-DO traffic channel, the AT may send a nullDRC to indicate that it does not want to receive any data from the networkwhile it is monitoring the 3G-1X paging channel. If there is no page messagefor the AT on the 3G-1X system, the AT would come back to the 1xEV-DOsystem to resume its data connection by pointing a non-null DRC to somesector. If there is a page message for the AT, the AT would stay in the 3G-1Xsystem to continue call setup procedures.

Operation and maintenance ofEVDO Components:2 EV-DO bts (1 CARRIER EACH)Is currently installed in MUMBAI-4 (RCS-38,39) which are visible through EMS GUI

http://97.241.222.64:8001.One has to install the JAVA RUNTIME ENV2 (j2re-1_4_1-windows-i586.exe) to view theapplication.It can be downloaded from internet or can be collected from me. One will be needing adminpassword for PC to be able to install it.
http://97.241.222.64:8001/http://97.241.222.64:8001/

Documents

Evdo Presentation