Enhanced Radio Access Technologies for Next Generation Mobile Communication phần 7 doc

The reverse rate control is for quality management of the reverse traffic channel,and the base station controls the reverse rate of the terminal based on probability.. However, if therev

3.2 1xEV-DO

• Coverage & LBA

The coverage of the 1xEV-DO network refers to a zone where the service is provided

at a certain throughput or higher throughput, or a zone with a certain C/I level orhigher level C/I refers to the ratio between signal and interception “C” indicatesthe transmission power from the base station, and “I” indicates all interceptionsignal power except carrier power C among the received power example of forward

LBA could be found in Table 5.

g N0 d Transmission loss between the AT and the AP

g My d Transmission loss between Ith AP and the AT in Jth sector

• Do System Capacity

The forward link capacity of the 1xEV-DO network is determined by the MACIndex

count that physically identifies the users Table 6 shows the MAC Channel and

preamble use versus MACIndex, and total 59 MACIndex values can be used astraffic channels:

In the channel card of the 1xEV-DO, there are 96 reverse channels Therefore,when there are three sectors, each sector will have 32 channels

Unlike the CDMA 2000 1x network, in the 1xEV-DO network, it is the sectorthroughput, not the number of subscribers, which must be managed for the operation

of the system Depending on the location of the user and the number of users, theactual sector throughput may drop below 2.4 Mbps, which is the maximum physicalthroughput Major factors that affect the throughput include the early terminationand multi-user diversity gain

Early termination occurs when the terminal requests a DRC that uses multi slots

with repeated symbols, see Table 7 The terminal responds by sending an ACK

through the ACK channel when correct demodulation is made before receivingall slots that the base station sends When the base station receives the ACK, itwill terminate the transmission without repetition In short, transmission will becompleted within a shorter slot time and the throughput will increase

Multi-user diversity gain refers to an increase in sector throughput caused bycharacteristics of the proportional fair scheduler The scheduler allocates the slots

to the user in a relative better condition Therefore, when there are multiple users,

it is highly likely that uses in better conditions will be selected, hence increasing

Table 5 Forward LBA

1x EV-DO Forward Link

Multi-user Diversity Gain [dB] 225

Building Penetration Loss [dB] 15 n

Figure 20 Throughput by number of users and idle slot gain

User i requests to the reverse link, and Ri(N) is the average rate of data that User

i received during Tc, the time constant in the scheduler Ri(N) can be updated

as follows:

RiN = 1 − 1/Tc∗RiN− 1 + 1/Tc∗(Served Rate In Slot N-1 To User i)

As the default of Ri(N) is “0”, the terminal that attempts to use the service for thefirst time in the cell will have priority The user for whom the data transmissionhas not been allocated in the current slot will have a served rate of 0, and eventhe average rate of the user who does not have data to transmit in the buffer will

be updated This leads to giving a higher priority to the user who has not recentlyreceived the data

The reverse rate control is for quality management of the reverse traffic channel,and the base station controls the reverse rate of the terminal based on probability

In case reverse traffic increases, the system load will also rise However, if thereverse traffic crosses the threshold, the base station will set the Reverse ActivityBit (RAB) as “1” and sends the RAB to the terminal through the RA channel After

receiving “1” as the RAB, the terminal lowers the reverse rate based on the ratetransition probability If the system load is smaller than the threshold, the RAB will

be “0” and the terminal will increase its transmission rate based on rate transitionprobability

4.

4.1 Network Structure and Functional Elements

The data core network in the CDMA2000 network is configured as shown in

Figure 21:

• Packet Data Serving Node (PDSN)

The PDSN allocates the IP addresses to the terminal through the PPP protocol,routes the packets between the terminal and the Internet network, and providesservices according to user’s authority given by the AAA Based on the data collectedthrough the signaling of the RP interface and packet use by the user, the PDSNcreates the charging data and sends it to the charging equipment

• Authentication, Authorization, Accounting (AAA) Server

When the user makes a new data call, the AAA server allocates the IP address andauthenticates the user Also, the AAA sends user authority data to the PDSN so thatthe PDSN can judge which users have access to which services The AAA server

Figure 21 Core network structure

receives the charging data created when the user uses the packet data service fromthe PDSN, and executes charging features.

• Home Agent (HA)

When the user requests mobile IP service, the PDSN sends mobile IP user data tothe HA After receiving this data, the HA allocates the IP address to the terminal,and uses two addresses to transmit packets using the PDSN as a foreign agent.Tunneling protocol is used between the PDSN and the HA

4.2 IMS

IMS stands for the IP Multimedia CN Subsystem, and is a core network domainthat provides various IP-based multimedia services that are controlled by the SIP.The term “IMS” was first introduced when the 3GPP adopted the All-IP concept inRelease 5, and since then, the IMS has been evolving through R5 and R7 Recently,the 3GPP2 and the fixed NGN network also adopted the IMS and are standard-

izing the related technologies, see Figure 22 The IMS adopted IETF standard

protocols such as SIP and Diameter, and defined various capabilities necessary forthe communication services to support global roaming and interworking

4.3 Standardization Trend

The IMS, a standard for the IP multimedia service in the GPRS network was firstdefined in R5 specification of the 3GPP In the same period, the 3GPP2 was alsostandardizing a technology similar to the IMS of the 3GPP Later, to harmonizethese two technologies, the 3GPP2 adopted the IMS of the 3GPP, not the All-IPstandard, as the MMM standard This has not yet changed In addition, the 3GPPdeveloped the IMS standard into R6 IMS through complementing the specification

to give access independence to R5 IMS

In this period, the TISPAN and ITU-T also recognized a need to introduceIMS technology to a fixed network To meet this need, a work item called FixedBroadband Access to IMS (FBI) is underway to integrate the IMS in a fixed-mobileconvergence network as part of works for establishing the R7

Figure 22 IMS Standard development

4.4 Terminal

The terminal is the endpoint that provides users with the services through thewireless communication network The terminal has been developed in a way tomeet various demands of users supporting multiple access networks and high datarate multimedia data services

• Terminal H/W Architecture

The hardware of the terminal mainly consists of three parts: the modem that processesthe call processing, the application that provides various value-added functions

and services, and I /O peripherals such as keypad and display as shown in Figure 23.

The modem part is one of the core hardware elements of the terminal anddeals with connections to the access network and manages data reception andtransmission Major modem parts includes the modem chip for baseband signalprocessing, the RF chip for the reception and the transmission of RF signals, thepower management chip, and the antenna

The application part is to handle various supplementary functions and multimediaservices other than basic call processing The application part includes variousapplication processors and memory devices

The I /O peripherals are exposed to the user The I/O peripherals include theLCD (Liquid Crystal Display), the camera, the speakers, the keypad, the externalmemory reader, and many other I/O devices

• Terminal S/W Structure

The software of the terminal consists of the operating system (OS) and the

applica-tions as shown in Figure 24 The terminal S/ W is based on Dual-Mode Subscriber

Software (DMSS), an MSM S/ W, and the REX OS for multitasking The terminalS/ W also includes a vendor-specific platform to support unique features of eachterminal over the operating system The DMSS controls the model chip and enablesinterworking between the modem chip and various application processors providing

a basic frame work for terminal S/ W operations The vendor-specific platform

Figure 23 Example of terminal H/W component

WAP MMS WIPI

Java

WIPI C WIPI Platform

HAL (Handset Abstraction Layer)

Product Company Platform

Product Company Main H/W (Audio, Camera, Moving, MP3)

MSM Chip CDMA S/W (DMSS) & REX OS

• Overall WIPI Architecture

Figure 24 Example of terminal S/W architecture

processes features of each terminal such as address book, SMS and MP3 playerand interworks with a higher layer platform On the Hardware Abstraction Layer(HAL) above the vendor-specific platform, the application platform is installed torun various applications

Korea adopted the Wireless Internet Platform for Interoperability (WIPI) platform

as the standard, and all supplementary service applications are developed in C orJava language based on the WIPI

• Terminal Evolution

The terminal evolution trend is mainly divided into two major streams: the supportfor the high data rate multi-access network and device convergence The modemchipset is being developed in a way to support not only basic communicationfeatures of the IS-95A network in the early days but also various features of newlyintroduced access networks such as CDMA2000 1x, 1xEV-DO, and WCDMA

to catch up with the access technology evolution From the device convergencepoint of view, the terminal has been developed to have various designs and toreduce overall weight and size Together with adopting System On Chip (SOC), theterminal is now developing into an integrated multimedia device that can supportnot only the basic voice calls but also the advanced and sophisticated multimediaservice features

5 FUTURE DEVELOPMENT

5.1 CDMA2000 TRM (Technology Road Map)

• IS-95

The IS-95A (Interim Standard 95A) is the first standardized CDMA technology

As the first digital mobile communication technology, the IS-95A was standardized

in 1993 and upgraded later to the IS-95B The IS-95 is recognized as the generation mobile communication technology by the International Telecommuni-

second-cation Union (ITU), see Figure 25.

• CDMA2000 1x

The CDMA2000 1x is the next-generation technology of the IS-95 1x is an viation of 1x Radio Transmission Technology, (1xRTT) which means a system thatuses one 1.25MHz channel The CDMA2000 1x system supports up to 3xRTT, and1xRTT is the most basic system The ITU classified the CDMA2000 1x technology

abbre-as 3G technology (in November 1999)

• CDMA2000 1xEV-DO (1x Evolution-Data Optimized)

The 1xEV-DO is a dedicated standard for the data service and has been developedbased on the CDMA2000 1x technology to provide mobile data service at a highspeed The ITU classified the 1xEV-DO as a 3G technology Following 1xEV-DORelease 0 (CDMA2000 High Rate Packet Data Air Interface, IS-856) and 1xEV-DORev A (TIA-856-A), 1xEV-DO Rev B was standardized

Figure 25 CDMA Technology TRM

The performance of the forward link in Revision A has increased by 20% due tothe introduction of improved packet structure and equalizer compared to EV-DO

Release 0, see the performance comparison in Figure 26 The improved packet

structure and the equalizer increased the C/I of the signal received by the terminal

so that a 1xEV-DO Revision A can support 3.1Mbps of the peak data rate.However, the most significant characteristic of 1xEV-DO Revision A is greatlyenhanced performance of the revers link compared to Release 0, see the performance

comparison in Figure 27 While Release 0 supports 153.6kbps of the peak data rate,

Revision A supports 1.8Mbps This improvement was due to the introduction andapplication of new technologies such as higher modulation schemes, Rx civersity,pilot interference cancellation, and packet prioritization

to greatly improve the performance of the forward link so that it is expected thatthe the multimedia service can be provided through mobile Internet

Figure 26 Forward link performance comparison (Aggregate throughput)

Figure 27 Reverse link performance comparison (Aggregate throughput)

Revision B introduced the scalable bandwidth technology and significantlyenhanced the maximum throughput of each user in the forward and reverse link

Figure 28shows the comparison of the throughput of Revision A and Revision B

• Flexible Carrier Assignment

The scalable bandwidth technology adopted by Revision B is to increase the

throughput by using multiple carriers at the same time, as shown in Figure 29.

Figure 28 Comparison of throughput of Revision A and Revision B

Figure 29 Flexible carrier assignment

Minimum one and maximum 15 carriers can be used at the same time In case three1.25MHz carriers are used, 14.7Mbps of the peak data rate will be possible, or incase 15 carriers are used, 73.5Mbps of the data rate will be possible Therefore,one to three carriers can be used for the mobile terminal, and four or more carrierscan be used to transmit 3D game data or high-resolution video data, which meansmore various types of services can be provided for users

In the 1xEV-DO Revision B system, the spreading factor of the system is notchanged and each 1.25MHz carrier is used as one unit Therefore, unlike HSDPA(The carrier bandwidth : 5MHz), Wibro (The carrier bandwidth : 9MHz), and othertechnologies which use the carrier of broad bandwidth, the frequencies do not need

to be adjacent so that frequency operation is more flexible, see an example of

frequency allocation in Figure 30.

• Flexible Duplexing

The flexible duplexing feature has been adopted to Revision B Flexible duplexing is

an advanced form of scalable bandwidth technology It uses an additional unpaired

Figure 30 Example of frequency allocation

Figure 31 Flexible duplexing example

spectrum (for TDD service frequency) to increase the transmission capacity of the

forward link, see an example in Figure 31.

• Upgrade From Revision A To B

As Revision A and Revision B are highly compatible, through a simple S/W upgrade,Revision A can evolve into Revision B However, simple S/W upgrades does notprovide all features of Revision B, and some features require H/W upgrades

5.4 Major Rival Technologies

Revision B is expected to compete with standards that pursue High Data Rate(HDR) service Major rivals will be HSDPA (or HSUPA) and Mobile WiMAX,and is expected to be commercialized between the end of 2006 and early 2008 like

Revision B, see the comparison with major rival technologies in Table 8.

5.5 HSDPA (High Speed Downlink Packet Access)

The HSDPA is a fast forward link packet data service that is based on the WCDMARelease 5 standard It includes a TDD mode that uses 5MHZ of broadband and

Table 8 Comparison with major rival technologies

Charateristics Title 1xEV-DO

an FDD mode that supports 1.25MHz of a narrow band In the TDD mode, theHSDPA supports 14Mbps of the peak data rate for the forward link and 2Mbps forthe reverse link The HSDPA is expected to have advantages over other services inthe global roaming, because 85% of the mobile communication service providersadopt WCDMA compatible standards.

5.6 Mobile WiMAX

Mobile WiMAX is a mobile communication service that complies with 802.16e,and is the most similar to Korea’s Wireless Broadband Internet (WiBro) that uses

a 2.3 GHz band and is scheduled to be serviced early 2006 Unlike Revision B,

an FDD-based service, the WiBro is based on the TDD and can change the timeratio between the forward and the reverse link Therefore, the WiBro is moresuitable for data services with large forward link traffic volume Unlike existing dataservice technologies that adopted CDMA-based modulation technique, the WiBroadopted the OFDM-based modulation technique to provide more reliable perfor-mance in urban areas with high multipath fading and to more easily adopt broadbandservices

6 ABBREVIATION

Access Channel A Reverse CDMA Channel used by mobile stations for nicating to the base station The Access Channel is used for short signaling messageexchanges, such as call originations, responses to pages, and registrations TheAccess Channel is a slotted random access channel

commu-Access Network (AN).The network equipment providing data connectivity between

a packet switched data network (typically the Internet) and the access terminals

An access network is equivalent to a base station

Access Terminal (AT).A device providing data connectivity to a user An accessterminal may be connected to a computing device such as a laptop personal computer

or it may be a self-contained data device such as a personal digital assistant Anaccess terminal is equivalent to a mobile station

Active Set. The set of pilots associated with the CDMA Channels containingForward Traffic Channels assigned to a particular mobile station

AMPS.Advanced Mobile Phone Service

ARQ. Automatic Repeat Request Technique for providing reliable delivery ofsignals between communicating stations which involves autonomous retransmission

of the signals and transmission of acknowledgments until implicit or explicit mation of delivery is received

confir-Authentication.A procedure used by a base station to validate a mobile station’sidentity

Base Station. A fixed station used for communicating with mobile stations.Depending upon the context, the term base station may refer to a cell, a sectorwithin a cell, an MSC, or other part of the wireless system See also MSC.

bps.Bits per second

BPSK.Biphase shift keying

Broadcast Control Channel.A code channel in a Forward CDMA Channel usedfor transmission of control information and pages from a base station to a mobilestation

CDMA.Code Division Multiple Access

CDMA Channel.The set of channels transmitted between the base station and themobile stations within a given CDMA frequency assignment

Chip Rate.Equivalent to the spreading rate of the channel It is either 1.2288 Mcps

FDMA Frequency Division Multiplexing Access

Forward CDMA Channel. A CDMA Channel from a base station to mobilestations The Forward CDMA Channel contains one or more code channelsthat are transmitted on a CDMA frequency assignment using a particular pilot

PN offset

Forward Fundamental Channel.A portion of a Forward Traffic Channel whichcarries a combination of higher-level data and power control information

Forward Common Control Channel.A control channel used for the transmission

of digital control information from a base station to one or more mobile stations

Forward Dedicated Control Channel. A portion of a Radio Configuration 3through 9 Forward Traffic Channel used for the transmission of higher-level data,control information, and power control information from a base station to a mobilestation

Forward Power Control Subchannel.A subchannel on the Forward FundamentalChannel or Forward Dedicated Control Channel used by the base station to controlthe power of a mobile station when operating on the Reverse Traffic Channel