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1x EVDO1x EVDO

ByYogesh Dave

Sachin VarshneyCDMA Testing Team, Mumbai

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1x = single 1.25 MHz carrier

EV = Evolution

DO = Data Optimized or Data only

EV-DO orEVDO and often EV, is a telecommunications standard for thewireless transmission of data through radio signals, typically forbroadbandInternet access. It uses multiplexing techniques including Code divisionmultiple access (CDMA) as well as Time division multiple access (TDMA)to maximize both individual user's throughput and the overall systemthroughput. It is standardized by 3rd Generation Partnership Project 2(3GPP2)

Why the name 1xWhy the name 1x--EVEV--DODO

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Why the name 1xWhy the name 1x--EVEV--DODO

EVDO was designed as an evolution of the CDMA2000 (IS-2000) standardthat would support high data rates and could be deployed along side awireless carrier's voice services. An EVDO channel has a bandwidth of1.25MHz, the same bandwidth size that IS-95A (IS-95) and IS-2000(1xRTT) use. The channel structure, on the other hand, is very different.

The EV-DO feature of CDMA2000 networks provides access to mobiledevices with forward link air interface speeds of up to 2.4 Mbit/s with Rev. 0and up to 3.1 Mbit/s with Rev. A. The reverse link rate for Rev. 0 canoperate up to 153 Kbit/s, while Rev. A can operate at up to 1.8 Mbit/s. Itwas designed to be operated end-to-end as an IP based network, and so itcan support any application which can operate on such a network .

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EVDO ArchitectureEVDO Architecture

EV-DO implementation is the same as 1X architecture system but withoutusing Mobile Switching Center (MSC).

EV-DO uses 1.25 MHZ carrier frequency (MC-1X).

When users transmit data, data packets will be sent from wireless devicethrough air interface towards BTS. Data packets then forwarded to BSC.BSC will forward data to PCF, who will forward it to PSDN.

For receiving data, data packets for users will be prepared in the providersIP network then forwarded by PDSN to PCF/BSC

Cell site, towers, antenna share carrier frequency between 1x and 1xEV-

DO. 1xEV-DO can reach peak rate 2.4Mbps on forward link (from BS to device),

and 153.6 Kbps on reverse link (from device to BS)

1x and 1xEV-DO uses the same PDSN in the network

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1x EVDO1x EVDOIP Data onlyIP Data only

Uke Kurniawan Usman - 20055

IS-2000

IP

BTS

IS-2000

IP

BTS

IPBS

C IP

Rout r

PDSN HomAg nt

IP

Fir wallIP

Rout r

Int rn t

Pri ataData

Network

IPBTS - IPBa eTran ei erStationIPBSC - IPBa eStation ControllerAAA - Authenti ation, Authori ation,

an A ountingPDSN - Pa ket Data Ser ing NodeHome Agent - obileIP Home Agent

AAA

RADIUSoverUDP/IP

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Rel 0Rel 0

This version was released in 2000 which introduced the EV-DO technology inCDMA.

Datarate:

EV-DO allowed data rates of up to 2.4 Mbps on forward link [download speed]and 154 Kbps reverse link [upload speed].

Features:It supports all IP network.It allows high data rates when compared to CDMA1X.

Services:http [ internet browsing].Voice on Demand.Movies on Demand.

3 revisions of EV3 revisions of EV--DO technologyDO technology

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Rel 0 forward link channel structureRel 0 forward link channel structure

The primary characteristic that differentiates an EV-DO channel from a1xRTT channel is that it is Time Multiplexed on the forward link (from thetower to the mobile). This means that a single mobile has full use of theforward traffic channel within a particular geographic area (a sector) duringa given slot of time. Using this technique, we are able to modulate each

users time slot independently. The forward channel is divided into slots, each being 1.667 ms long. In

addition to user traffic, overhead channels are interlaced into the stream.These include the Pilot which helps the mobile find and identify the channel,the Media Access Channel (MAC) which tells the mobiles when their data isscheduled, and the Control Channel, which contains other information thatthe network needs the mobiles to know.

The modulation to be used to communicate with a given mobile isdetermined by the mobile itself. It listens to the traffic on the channel, anddepending on the receive signal strength along with the perceived multi-path and fading conditions, makes its best guess as to what data-rate it cansustain while maintaining a reasonable frame error rate of 1-2%.

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Rel 0 forward link channel structureRel 0 forward link channel structure

This allows us to serve users that are in favorable RF conditions with verycomplex modulation techniques while also serving users in poor RFconditions with simpler and more redundant signals.

It then communicates this information back to the serving sector in the formof an integer between 1 and 12 on the "Digital Rate Control" (DRC) channel.

The DRC values are as follows:

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DRCDRC

IndexIndex

Data rateData rate

in kbpsin kbps

SlotsSlots

scheduledscheduled

PayloadPayload

size (bits)size (bits)Code RateCode Rate

ModulatioModulatio

nn

1 38.4 16 1024 1/5 QPSK

2 76.8 8 1024 1/5 QPSK

3 153.6 4 1024 1/5 QPSK

4 307.2 2 1024 1/5 QPSK

5 307.2 4 2048 1/5 QPSK

6 614.4 1 1024 1/3 QPSK

7 614.4 2 2048 1/3 QPSK

8 921.6 2 3072 1/3 QPSK

9 1228.8 1 2048 2/3 8-PSK

10 1228.8 2 4096 1/3 8-PSK

11 1843.2 1 3072 2/3 16-QAM

12 2457.6 1 4096 2/3 16-QAM

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Rel 0 reverse link structureRel 0 reverse link structure

The reverse link (from the mobile back to the Base Transceiver Station) onEVDO Rev. 0 operates very similar to that of3G1X CDMA. The channelincludes a reverse link pilot (helps with decoding the signal) along with theuser data channels. Some additional channels that do not exist in 3G1Xinclude the DRC channel (described above) and the ACK channel (used for

HARQ). Missing from the reverse link is any sort ofPower control, becausethe forward link is always transmitted at full power for use by all the mobiles.

All of the reverse link channels are combined using code division andtransmitted back to the base station using QPSK where they are decoded.The maximum speed available for user data is 153.2 kbps, but in real-lifeconditions this is rarely achieved. Typical speeds achieved are between 20-

50 kbps.

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Rev ARev A

Revision A of EVDO makes several additions to the protocol while keepingit completely backwards compatible with Revision 0.

These changes included the introduction of several new forward link datarates that increase the maximum burst rate from 2.45 Mbit/s to 3.1 Mbit/s.Also included were protocols that would decrease connection establishmenttime (called enhanced access channel MAC), the ability for more than onemobile to share the same timeslot (multi-user packets) and the introductionofQoS flags. All of these were put in place to allow for low latency, low bitrate communications such as VoIP.

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DRC IndexData rate in

kbps

Slots

scheduledPayload size

(bits)Code Rate Modulation

13 1536 2 5120 12-May 16-QAM

14 3072 1 5120 6-May 16-QAM

The additional forward rates for EVDO Rev. AThe additional forward rates for EVDO Rev. A

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.

In addition to the changes on the forward link, the reverse link wasenhanced to support higher complexity modulation (and thus higherbit rates).

An optional secondary pilot was added, which is activated by themobile when it tries to achieve enhanced data rates.

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EV-DO Rev B is a multi-carrier evolution of the Rev A specification. It

maintains the capabilities of EVDO Rev A, and provides the followingenhancements:

Higher rates percarrier(up to 4.9 Mbit/s on the downlink per carrier). Typicaldeployments are expected to include 3 carriers for a pea rate of 14.7Mbit/s

Higher rates by bundling multiple channels together enhance the user

experience and enables new services such as high definition videostreaming.

Uses statistical multiplexing across channels to further reduce latency,enhancing the experience for latency-sensitive services such as gaming,video telephony, remote console sessions and web browsing.

Increased talk-time and standby time

Hybrid frequency re-use which reduces the interference from the adjacentsectors and improves the rates that can be offered, especially to users at theedge of the cell.

Efficient support for services that have asymmetric download and uploadrequirements (i.e. different data rates required in each direction) such as file

transfers, web browsing, and broadband multimedia content delivery.

Rev BRev B

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How does EVDO compare to other 3G Technologies ?

Networ Max DataRate

DownloadTime

GSM 9.6 Kbps 41 minutes

IS95-A CDMA 14.4 Kbps 31 minutes

GPRS 45 Kbps 9 minutes

IS95-B CDMA 64 Kbps 6 minutes

CDMA2000 1x 307 Kbps 1.5 minutes

W-CDMA 384 Kbps 61 seconds

CDMA2000-1xEV-DO

2.4 Mbps 11 seconds

Cost per MBytes for different wireless network

Tec nology Networ Cost per Mbyte

GPRS $.415

W-CDMA $.069

CDMA2000 1x $.059

CDMA2000-1xEV-DO $.022

Download Time of 3 minutes MP3 file

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Conclusion

3G Technologies continue leading wireless WAN and EV-DO is theevolution of CDMA 1x to support data at rates comparable to broadbandcable connections.

-- Higher Data rates and Capacity

Three dimensions of wireless technology evolution Higher spectral efficiency (lower cost)

Enhanced services (new revenue streams)

Higher peak rates (for bursty apps)

EV-DO support the full range of services High-Speed Download and Upload, Voice, Push-to-Connect, Video

Telephony, and Multicast, VoIP

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References and footnotes

3G - CDMA2000 1xEV-DO Technologies. CDMA development Group.

CDMA2000 1xEV-DO. QUALCOMM Technology and Solutions.

EVDO high data rate system", IEEE Wireless Communications and

Networking Conference, IEEE, pp. 389-395

A Forward Link Performance Study of the 1xEV-DO Rev. 0 System UsingField Measurements and Simulations (PDF). Lucent Technologies.

Gopal, Thawatt (11-15 March 2007), "EVDO Rev. A Control Channel

Bandwidth Analysis for Paging", IEEE Wireless Communications andNetworking Conference, IEEE, pp. 3262-7, doi:10.1109/WCNC.2007.601

Cdma2000 High Rate Packet Data Air Interface (PDF). 3GPP2 (July2005).

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