Real-World Experience with a Mobile Broadband … Experience with a Mobile Broadband Network Dr. Jin...

Real-World Experience with a Mobile Broadband Network

Dr. Jin YangVerizon Wireless

[email protected]

September 23, 2004IEEE Communications SocietyOakland-East Bay Chapter, CA

2JYang – IEEE Presentation

Outline

Introduction Overview of 1xEV-DO NetworkPerformance of SchedulerPerformance of Hybrid ARQ An Integrated cdma2000-1x and 1xEV-DO NetworkConclusions


Introduction

Applications drive architecture • Traditional wireless network: voice centric

• Low data rate• Low latency• Equal and stringent service quality

• Evolutional wireless network: versatile applications beyond voice• Very high data rate• Flexible latency• Flexible service quality

Mobile wireless data network is evolving to support broadband services• Large file transfer• Intranet and Internet• Multimedia


Wireless Broadband Technologies

cdma2000-1x Rev C/D

W-CDMARel. 4

HSDPARel. 5

1xEV-DO Rev A

cdma2000-1x1xRTT

1xEV-DO Rev 0

GSM/GPRS

EDGE

cdmaOneIS-95A/B

3GPP2 Standards

3GPP Standards

CDMA2000-1x Rev E

IEEE Standards

802.16d 802.16e

802.11b 802.11a 802.11gWiFi

802.20Flarion and others

HSUPA Rel. 6+

WiMax

802.11n

1xEV-DORev B


Data Rate vs. Coverage Distance

10 kbps

100 kbps

1 Mbps

100 Mbps

1m 100 m10 m 1,000 m 10,000 m

UWB

802.11b

802.11g

WCDMAcdma2000-1x

GSM/GPRS/EDGE

HSDPA1xEV-DO1xEV-DVBluetooth

Data Rate

Distance in meter

10 Mbps 802.11a

UWB*

802.16d

802.20Flarion

802.11n

ZigBee

Standards available, no commercial productsStandards and commercial products available Standards under development


TIA/EIA IS-856 1xEV-DO

1xEV-DO is an integral part of the cdma2000 family of standards developed by 3GPP2, and approved by ITU as IMT-2000 system for 3G to address MOBILE broadband access• Peak rate 2457.8 kbps on forward link for 1xEV-DO Rev 0

• 1xEV-DO Rev A supports peak rate 3072 kbps on forward link, 1843.2 kbps on reverse link

• Forward link throughput increased by • Full power transmission• Adaptive modulation and coding (AMC)• Hybrid Automatic Repeat reQuest (H-ARQ)• More efficient scheduling and multiple user diversity

• IP based packet data architecture


Overview of 1xEV-DO: AMC

1/31/31/31/31/31/31/31/31/51/51/51/5

Code Rate

16QAM8PSK

16QAMQPSK8PSKQPSKQPSKQPSKQPSKQPSKQPSKQPSK

Modulation Slots per Packet

Physical LayerData Rate (kbps)

12457.611843.221228.811228.82921.62614.41614.44307.22307.24153.6876.81638.4

Adaptive server selection, Adaptive Modulation and Coding (AMC)• The best server, modulation and coding schemes are adaptive to the

channel carrier-to-interference ratio (CIR) based on feedback from reverse link Data Rate Control (DRC) channel at 600 Hz rate


Overview of 1xEV-DO: Scheduler and H-ARQ

Fast Scheduler• Fast scheduler takes into account a-priori channel state information from DRC• Users are served when experiencing better than average channel Carrier-to-

Interference Ratio (CIR)• Aggregated sector throughput increases as number of users increases due to

scheduler taking advantage of multi-path fading diversity from users

Hybrid ARQ• Earlier termination (an ACKnowledgment received earlier) will increase the

effective throughputTransmitSlot 1

n n + 1 n + 2 n + 3 n + 4 n + 5 n + 6 n + 7 n + 9 n + 10 n + 11n + 8 n + 12

TransmitSlot 2

TransmitSlot 3

TransmitSlot 1

Slots

NAK‘1’

NAK‘1’

ACK‘0’

First slot for the next packet transmission

Effective throughput 204.8=(153.6 x 4/3)

Instead of 153.6 kbps

FL Transmissionwith 153.6 kbps(4 slots)

DRC Requesting 153.6 kbps

ACK ChannelTransmission


Overview of 1xEV-DO: Phy & App Throughput

The average physical and application layer throughput for ftp transmission over a trial network

0-2 0 2 4 6 8 10 12 14

Ave

rage

Thr

ough

put

(kbp

s)

0

500

1000

1500

2000

2500

-2 0 2 4 6 8 10 12 14Average Carrier-to-Interference Ratio (dB)

Physical Layer Throughput: Measured PredictedApplication Layer Throughput: Measured Predicted


Scheduler

Scheduler determines slot assignment for each user• Advanced scheduling scheme improves the spectrum efficiency

Proportional fairness algorithm• Scheduling based on channel condition, time allocation history and user

data on the pipe• Serving the user at better than average channel conditions and achieving

multiple user diversity gain• User throughput optimized to the maximum achieve level regardless of

other user RF conditionsFairness versus throughput efficiency tradeoff• Gives higher priority and longer time allocation to good RF condition

could increase aggregated sector throughput at the cost of poor RF condition user

• Absolutely equal throughput for all users will sacrifice network efficiency Scheduler based on class of service requirement• Higher priority on time allocation can be used to differentiate services,

support delay-sensitive or rate-sensitive applications


Scheduler: Time Allocation Per User

The proportional fairness scheduler provides fair chance for every user who needs to transmit data• Users under poor,

average and good RF conditions share similar CDF of time allocations

• The average percentage of time allocation for each user is around 25% when 4 users are active in the system

• The good RF condition user in a mixed RF scenario did not dominate radio resources on time basis

Percentage of Time Allocation Per Second

CD

F

00.10.20.30.40.50.60.70.80.9

1

0 75% 100%0

0.10.20.30.40.50.60.70.80.9

1

0 25% 50%

Edge Middle NearPercentage of Time Allocation Per Second

CD

F

00.10.20.30.40.50.60.70.80.9

1

0 75% 100%0

0.10.20.30.40.50.60.70.80.9

1

0 25% 50%

Edge Middle Near

CD

F

00.10.20.30.40.50.60.70.80.91

-2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14Carrier-to-Interference Ratio (dB)

Edge Middle Near

CD

F

00.10.20.30.40.50.60.70.80.91

0.10.20.30.40.50.60.70.80.91

-2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14Carrier-to-Interference Ratio (dB)

Edge Middle Near


Scheduler: Throughput Performance

The sector throughput increases as number of users increases. The user throughput increases as the radio condition improves

• The multiple users gain is particularly strong under poor RF conditions• Aggregated throughput of 4 and 16 users could increase to 2 and 3.4 times that of

a single user throughput, respectively• The throughput will be saturated as the number of users increases to more than 4

under good RF conditions

0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500

1 2 4 8 16Number of Active Users

Measured: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dBTheoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dB

0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


Theoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dBTheoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dB

0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


Sec

tor T

hrou

ghpu

t (kb

ps)

0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


Measured: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dBTheoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dBMeasured: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dB

Theoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dB

0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


Theoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dBTheoretical: CIR=0.4 dB CIR=5.9 dB CIR=10.3 dB

0

500

1000

1500

2000

2500

1 2 4 8 160

500

1000

1500

2000

2500


Sec

tor T

hrou

ghpu

t (kb

ps)


Hybrid ARQ

Hybrid ARQ provides further control mechanism to improve the data rate under adverse radio conditions • Hybrid ARQ enables early-termination of multi-slot transmission on physical

layer and increases the user data rate. The chart illustrates the scheduled and final served data rate for a user moving at the edge of a sector• Hybrid ARQ results in a new set of derived packet types with increased rate

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

38.4 68.26 76.8 87.77 102.4 153.6 204.8 307.2 409.6 614.4 921.6 1228.8 1843.2 2457.6

Data Rate (kbps)

Perc

enta

ge o

f Rat

es

Scheduled Rate Served Rate


Hybrid ARQ: Throughput Gain

Hrbrid ARQ supports up to 1 dB throughput gain across network• The hybrid ARQ gain is significantly higher when mobile is at edge of the cell

with vehicular speed, where a-priori channel estimate is not accurate due to highly unpredictable channel conditions and interference patterns

• The gain is minimal when the user is near the cell with good a-priori channel state information

Hybrid ARQ combined with AMC and scheduler results in high average sector throughput across various RF environments

0.0

0.2

0.4

0.6

0.8

1.0

Hyb

rid A

RQ

Gai

n (d

B)

0 2 4 6 8 10 12Carrier-to-Interference Ratio (dB)

Pedestrian Vehicular Stationary


An Integrated Network Solution

1xEV-DO is an integral part of the cdma2000 family of standards• The same 1.2288 MHz frequency bandwidth• The similar reverse link budget enables one-to-one overlay of 1xEV-DO

on existing cdma2000-1x network • Hybrid mode supports smooth seamless hand-off between 1xEV-DO and

cdma2000-1x• cdma2000-1x voice calls are successfully terminated and originated during

1xEV-DO active data session using the trial network

A highly integrated network architecture provides a spectrum efficient way for both delay sensitive voice and delay tolerant data services• The integrated network can share packet data network elements, such as

Packet Data Serving Node (PDSN), Foreign Agent (FA), Authentications, Authorization and Accounting (AAA), and Home Agent (HA)

• Only Radio Network Controller (RNC) and dedicated 1xEV-DO base station modem cards are needed to upgrade the existing cdma2000-1x network


VisitedAAA

HomeAAA

PDSN/FA HA

An Integrated Network: Architecture

HomeNetwork

R-P

IP Network

VisitedNetwork

HLRIOS

PSTN

BSC(cdma2000-1x)

RNC(1xEV-DO)

Multi-mode BTSMSC/VLR

AbbreviationsAAA Authentications, Authorization and AccountingHA Home AgentFA Foreign AgentIOS Interoperability StandardR-P Radio Packet InterfaceRNC Radio Network ControllerPDSN Packet Data Serving Node New network elements required for 1xEV-DO

1x

1xEV-DO

Shared network elements with cdma2000-1x

SS7Network

InternetGateway


An Integrated Network: Link Budgets

Reverse link budgets for 1xEV-DO and cdma2000-1x• The link budget of a 1xEV-DO system is similar to that of cdma2000-1x

under serving rate of 38.4 kbps

cdma2000-1x 1xEV-DOData Rate (kbps) 38.4 38.4Portable Tx ERP Power (dBm) 23 23Base Rx Antenna Gain (dB) 17 17Base Rx Cable Loss (dB) 3 3Receiver Sensitivity (dBm) -120.64 -120.80

Thermal Noise (dBm/Hz) -169.98 -169.98Noise Figure (dB) 4 4

Data Rate (dB -Hz) 45.84 45.84Eb/No Req. @ PER 3% (dB) 3.5 3.34

Total Link Margin (dB) 25.17 25.17 System Loading (75%) (dB) 6.02 6.02

Log-normal Std. Dev. (dB) 8.00 8.00 Fading Allowance (dB) 10.25 10.25

Soft Hand -off Gain (dB) 4.1 4.1Body Loss (dB) 3 3

Building/Vehicle Penetration Loss(dB) 10 10

Maximum Path Loss (dB) 132.46 132.62


Conclusions

The 1xEV-DO has achieved high data throughput and high spectral efficiency through a combination of adaptive modulation and coding, fast scheduler and hybrid ARQ The aggregated sector throughputs increases as the number of users increasesThe proportional fairness scheduler provides fair chance for each user to share radio resources in a timely manner with an efficient network throughputAn integrated 1xEV-DO and cdma2000-1x network can support both delay sensitive voice and delay tolerant data services

Real-World Experience with a Mobile Broadband … Experience with a Mobile Broadband Network Dr. Jin...

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