EVDO

Faculty

RTTC, TVM

Growth of Mobile Technology

• The first generation of mobile cellular systems -1980 - analog.

• The second generation (2G) – 1990 - digital technology - 2G was defined and designed to support voice and low-rate data.

• Enhanced version 2.5G was to improve voice quality, coverage, and capacity.

• The third generation cellular systems increase the system capacity and provide enhanced services such as voice and high-speed data.

• The third generation of cellular standards has seen a dominance of CDMA as the underlying access technology.

CDMA Family

• Code Division Multiple Access (CDMA) is a digital wireless technology that was pioneered and commercially developed by Qualcomm.

• The first CDMA-based cellular systems used IS-95A as the air interface standard.

CDMA Evolution

EV-DO

• EVDO, also known as EV-DO, 1xEvDO and 1xEV-DO.

• A standard for high speed wireless broadband. • The acronym is short for "Evolution, Data Only"

or "Evolution, Data Optimized". • The official name, defined by the

Telecommunication Industry Association, is "CDMA2000, High Rate Packet Data Air Interface".

EVDO

• Traditional wireless networks create a physical path between receiving and sending devices.

• EVDO adopts the approach used for the internet. IP, the Internet Protocol, breaks data into small pieces called packets.

• Each packet is sent independently of all the other packets.

• Saves bandwidth for use by other devices; when neither party on a phone call is speaking, the connection consumes no bandwidth because there are no packets to send.

EVDO

• EVDO is based on the 1xRTT standard.• The 1x in 1xRTT refers to 1x the number of 1.25MHz

channels. The RTT in 1xRTT stands for Radio Transmission Technology.

• 1xRTT 50Kbps - 100Kbps Upload and Download, bursts to 144Kbps.

• EVDO Rev 0 400kbps-700kbps Download, bursts up to 2.0Mbps, 50kbps-100kbps Upload Speed, bursts to 144Kbps.

• EVDO Rev A 500Kbps-1,000Kbps Download, bursts to 3.0Mbps, 300Kbps-400Kbps Upload Speed, bursts to 1.8Mbps.

EVDO Revisions

• Revisions denoted as Rev. 0, Rev. A, and Rev. B and so on.

• Rev. 0 supports forward link speeds up to 2.4 Mbit/s.

• Rev. A supports FL up to 3.1 Mbit/s.

•

EVDO Comparison to other technolgies

Advantages of EVDO

• An evolutionary system.• 1xEV-DO can support a data rate of up to

2.4576 Mbps using a bandwidth of only 1.25 MHz.

• 1xEV-DO takes advantage of the characteristics of some data services, which are:– Data rates are mostly asymmetrical– Latency can be tolerated– Transmissions are bursty in nature

In EVDO, Base station controls rate of data transmission at given constant transmit power

CDMA 1X EV DO Protocol Stack

Application Layer - Airlink packet and signaling applications.

Stream Layer- Multiplexing of applications with different QoS.

Session Layer - Protocol negotiation, Configuration, Session state maintenance.

Connection Layer - Airlink connection establishment and maintenance.

Security Layer - Authentication and encryption services.

MAC Layer - Procedures for receive and transmit over the physical layer.

Physical Layer - Channel structure, freq., power, modulation and encoding.

1xEV-DO uses a seven-layer protocol architecture between Mobile & PDSN.

• EVDO Network Structure

AT

HLR

PDSN

AAA

BTS BSC PCF

MSC

A10/A11

HA

ANAAA

Access Network ( 1x and DO )

EVDO NETWORK STRUCTURE

AT ： access terminal AN ： access network ， including BSC and BTS AN AAA ： AAA server for access network

Difference with 1x Reference NetworkDifference with 1x Reference Network

1xEV-DO is data only, so no interface to MSC/HLRThe Packet Data Domain equipment （ PDSN 、 AAA 、

HA ） is same as 1X Independent Access network AAA server Two A interfaces added:- A12 for access system authentication- A13 for AT roaming home AN and Foreign AN interaction

1xEV-DO Channel Overview1xEV-DO Channel Overview

Forward Link

• No power control of the forward link. AN transmits at constant power.

• Instead of variable power on the forward link, the AT requests variable rates on the forward link using the data rate control channel on the reverse link.

• AN deliver different data rates on the forward link based on feedback received from the ATs.

• The forward link uses time division multiplexing (TDM) to multiplex different channels (in addition to CDMA).

• No soft handoff on the forward link, and each AT is served by only one base station.

• EV-DO channels are Time Multiplexed on the forward link (from the tower to the mobile).

• The forward channel is divided into slots.• There are total 600 slots in one second.• 16 slots in one frame which is 26.66ms.• Each slot is 1.667 ms long. • User traffic, overhead channels are interlaced

into the stream.• Overhead channels include Pilot, Media Access

Channel & Control Channel.

Different channels on Forward Link

• Pilot channel – The pilot channel provides ATs with timing and phase

reference...

• Forward traffic channel/control channel– The forward traffic channel/control channel transports both

forward traffic channel MAC layer packets and control channel MAC layer packets

• The MAC channel consists of the following channels:– Reverse activity (RA) channel;– Reverse power control (RPC) channel;– DRC Lock channel

TDM of Forward Channels

Forward Link Overview Forward Link Overview The transmission rate is the rate requested by AT on the reverse link. Dedicated to a single AT at any given instant of time.

Pilot is embedded in the traffic stream (as opposed to a continuous transmitted pilot in IS-95).

Paging and Sync Channels are combined into a single Control Channel whose messages are time multiplexed on the “single user” forward link.

Forward link transmission is organized as 26.66…ms frames. Each frame consists of sixteen 1.66…ms slots. Each slot contains 2048 chips. Each slot is divided into two half slots with 1024 chips each.

No soft handoff TDMed, full power and variable rate (38.4 kbps ~ 2457.6 kbps) Adaptive coding and modulation (R = ¼, 3/8, and ½; QPSK, 8PSK and

16QAM) Interleaving, puncturing, repetition and symbol demultiplexing

Quadrature Spreading, baseband Filtering and up-converting

Reverse Link

• There is power control on the reverse link. • The AN can power control the reverse link by using the

reverse power control channel. • An AT can change its transmit power on the reverse link

based on feedback received from the AN.• There is soft handoff on the reverse link. In other words,

more than one base station can receive one AT’s transmission.

• There is no TDM on the reverse link. The reverse link channels are separated using CDMA.

Reverse Link

• Reverse traffic channel

• Access channel.

Reverse Link

• Reverse Traffic Channel• The reverse traffic channel is used to

transport both user data messages and signaling messages and consists of the:– Data channel;– Pilot channel;– Reverse rate indicator (RRI) channel;– Data rate indicator (DRC) channel;– ACK channel.

EVDO Channels

Simple Network StructureSimple Network Structure (End to End IP)(End to End IP)

Home Agent

• This is a router that, together with the foreign agent (FA), provides mobile IP functionality.

• The HA is a router that resides on that MS’ home IP network (served by that MS’ home PDSN).

• When the MS travels away from its home PDSN, the MS’ HAforwards those packets (destined for the MS) to the MS. In doing so, the MS’ HA must know on what PDSN the MS current resides.

Foreign agent (FA)

• This is another router that, together with the HA, provides mobile IP functionality.

• The FA is typically colocated with the PDSN. When an MS “visits” a foreign IP network (served by another PDSN), the FA on the foreign network receives packets forwarded from the MS’ HA and delivers them to the MS (that is currently on the foreign network).

EVDO Service FlowEVDO Service Flow

Session Setup Flow

New Concepts in 1xEV-DONew Concepts in 1xEV-DO

Session- Shared state between the access terminal and the access network

- This shared state stores the protocols and protocol configuration attributes that were negotiated and is used for communications between the access terminal and the access network;

- Information : A unicast address (UATI) that is assigned to the access terminal, the set of protocol configuration attributes is used by the access terminal and the access network to communicate over the air-link, etc

- When the value of protocol configuration attributes is changed, Session negotiation is performed between the access terminal and the access network. An access terminal cannot communicate with an access network without having an open session.

• AT will negotiate session with RNC – an EVDO session.

• ANAAA authenticates – Device credentials used as username & password.

• EVDO device is registered.

• Create Dial up Network. ISP authentication for PPP session. Between AT & PDSN.

New Concepts in 1xEV-DO (Cont.)New Concepts in 1xEV-DO (Cont.)

UATI (Unicast Access Terminal Identifier)

- A universally unique address that is assigned to each access terminal in a subnet

- As the 128-bit address is assigned but never required to be sent on the access channel, the access network can always send the short (32 bits) version of the UATI

FAN

BI

M

TRX

ReservedTRX

TRX

TRX

TRX

TRX

PSMD

PPM

PPM

PPM

PPM

PPM

PSMC

PSMC

HPA

HPA

HPA

HPA

HPA

HPA

BTM

RFE

RFE

RFE

RFE

RFE

RFE

RI

M

CHM

CHM

CHM

CHM

CCM

CCM

DSM

GCM

GCM

DSM

CDM

SNM

SAM

SNM

1

2

3

4

5

The Difference of Configuration

1. There is no TFS In the plug-in box ;

2. For the BDS Plug-in boxes , DSM 、 CDM 、 RIM 、 BIM 、 SNM are added in order to implement DO services;

BDS Plug-In Box

SDH Interface Module (SNM): It completes the SDH interface function. SNM provides active/standby configuration.

Site Alarm Module (SAM): It provides environment monitoring.

GPS Control Module (GCM): It provides an accurate GPS clock to the BTS. GCM supports active/standby configuration.

Data Service Module (DSM): It completes the function of Abis interface with BSC. DSM supports active/standby configuration.

BDS System Interface Module (BIM): It is BTS interface module and completes the interface switching between the master and slave BDSs, between BDS and RFS and between BTS and BSC.

Thank You !