Enhanced Radio Access Technologies for Next Generation Mobile Communication phần 6 potx

Its relation to HSDPA and WiMAX will be looked into Keywords: Mobile communication; CDMA2000 1X, Channel Structure, Transmission Scheme, Call Processing, Protocol Layers, Forward link, R

FUNDAMENTALS OF MULTI-CARRIER CDMA TECHNOLOGIES 145

(l= L + 1 · · · J) experiences zero-gain In addition, the signal in each channel isperturbed by an additive zero-mean complex-valued Gaussian noise, and the fadingand noise processes are assumed to be mutually statistically independent, respec-tively, and also mutually statistically independent each other The receiver, on theother hand, multiplies the received signal in each channel with an adequate weightand finally combines all the multiplier outputs The combiner output is written as

n= n1 n2· · · nJT(116)

w= w1 w2· · · wJT(117)

The following properties are defined for h, n and s:

where H and N are called “the correlation matrix (J×J) of the diversity channels”with non-zero eigenvalues of 2

s2· · · 2

sL” and “the correlation matrix (J× J)

of the noise,” respectively, IJ×J and 0J×J denote identity and zero matrices (J×J),respectively, and 2denotes the power of noise When h is fixed, the power of the

combiner output is written as

where Eh· denotes statistical average with h fixed In (123), the first and second

terms mean the powers of signal and noise, respectively, so the signal to noisepower ratio (SNR) of the combiner output is written as

2wHw

A solution of /w∗= 0 leads to a weight vector which maximizes the SNR,where ·∗denotes complex conjugate, but here we take another approach to reachthe optimum weight vector.

Let us consider the following eigenvalue problem:

(125) H h w = w

where  denotes “an eigenvalue of H h.” Defining max and wmax as the maximumeigenvalue and the eigenvector associated with it, respetively, of course, they satisfy(126) H h wmax= maxwmax

Pre-multiplying (126) by wmaxleads to

Eq (128) clearly shows that, if we select the weight vector as the eigenvector

corresponding to the maximum eigenvalue of Hh, it maximizes the SNR of the combiner output.

The rank of H h is 1 because it is defined as hhH, so the optimum weight vector

is wmax= h In fact, substituting the solution into (125) leads to

max= = h

2=L

l(131)

l=hl2

2 (132)

Eqs (131) and (132) show that, the maximum SNR of the combiner output is the

sum of the SNRs of the diversity branches The combiner with selection of wmax= h

is called “the Maximum Ratio Combiner (MRC).” In this case, the received wavesfrom L+ 1 to J are not used for data demodulation Therefore, we call this “adiversity system with order of L.”

FUNDAMENTALS OF MULTI-CARRIER CDMA TECHNOLOGIES 147

B: Bit Error Rate Expression

For binary phase shift keying (BPSK)/ coherent detection, it is well known that thebit error rate (BER) is given by

In the Appendix A, max in (133) has been derived with h fixed, so to calculate

the average BER for the diversity system with order of L in the fading channel, we

average (133) in terms of h, namely, max, because max is a function of h

(135) BERdiv Lfading= Eh BERmax= EmaxBERmax

where Eh· and Emax· denote statistical averages in terms of h and max,

respec-tively If we know the probability density function (pdf) of max as pmax, then

we can rewrite (135) as

(136) BERdiv L

0BERmaxpmaxdmax

The amplitude hl is complex valued-Gaussian-distributed with zero-mean, so

l given by (132) is exponentially distributed The pdf of l and the

charac-teristic function defined as Laplace Transform of the pdf are respectively

where l denotes the average SNR The characteristic function on the sum ofindependent variables is given by the product of the characteristic function on eachvariable, so it is written as

(140) smax=L

l=11/l

s+ 1/l

If lis different each other, by taking the inverse Laplace Transform of (140), the

pdf of max becomes

pmax= lim

→

12j

 +j

maxds=Ll=1

Res s

max l

=Ll=1

L

L

14lNote that (143) is also valid when l is identical Taking into consideration of

l= 2

sl/2, it is concluded that the BER is uniquely determined by the numberand magnitude of eigenvalues for the channel, namely, the degree of freedom ofthe channel of interest

C: Equivalence Through Linear Transformation

Now, assume that a receiver once linearly transforms the signals through J diversitychannels and then combines all the multiplier outputs In this case, the output ofthe combiner is written as

FUNDAMENTALS OF MULTI-CARRIER CDMA TECHNOLOGIES 149

Similar to the discussion in the previous section, defining G h as ggH= FhFhH,the SNR of the combiner output is written as

Consequently, any linear transformation of received signals cannot change theresultant SNR, that is

[4] N.Yee, J-P.Linnartz and G.Fettweis, “Multi-Carrier CDMA in indoor wireless radio networks,”

Proc of IEEE PIMRC’93, pp.109–113, Sept 1993.

[5] K.Fazel and L.Papke, “On the performance of convolutionally-coded CDMA/OFDM for mobile

communication system,” Proc of IEEE PIMRC’93, pp.468–472, Sept 1993.

[6] A.Chouly, A.Brajal and S.Jourdan, “Orthogonal multicarrier techniques applied to direct sequence

spread spectrum CDMA systems,” Proc of IEEE GLOBECOM’93, pp.1723–1728, Nov 1993.

[7] V.M.DaSilva and E.S.Sousa, “Performance of Orthogonal CDMA Codes for Quasi-Synchronous

Communication Systems,” Proc of IEEE ICUPC’93, pp.995–999, Oct 1993.

[8] S.Kondo and L.B.Milstein, “Performance of Multicarrier DS CDMA System,” IEEE Trans on

Commun., Vol.44, No.2, pp.238–246, Feb 1996.

[9] R.Prasad and S.Hara, “An overview of Multi-Carrier CDMA,” Proc of the 4th IEEE International

Symposium on Spread Spectrum Techniques and Applications (ISSSTA’96), pp.107–114, Sept.

1996.

[10] S.Hara and R.Prasad, “Overview of Multicarrier CDMA,” IEEE Communications Magazine,

Vol.35, No.12, pp.126–133, Dec 1997.

[11] S.Hara and R.Prasad, “Design and performanceof Multicarrier CDMA system in

frequency-selective Rayleigh fading channels,” IEEE Trans on Vehi Technol., Vol.48, No.9, pp.1584–1595,

CHAPTER 5

CDMA2000 1X & 1X EV-DO

SE HYUN OH1AND JONG TAE LHM2

1Senior Vice President, Strategy Technology Group, SK Telecom, Korea

2Vice President Mobile Device & Access Network R&D Center, SK Telecom, Korea

Abstract: In this chapter, we will discuss CDMA2000 1x and 1x EV-DO systems We will talk about

channel structure, transmission scheme, call processing, protocol layer and etc under the topic of radio access technology And we will talk about coverage & LBA, capacity, scheduling strategy, quality management and etc under the topic of Engineering & Operation technology Also, core network structure of CMDA2000 1x system will be mentioned, explanation focused on its main functional elements Also, characteristics and advancements of next generation technology of 1x EV-DO, EV-DO Rev A and EV-DO Rev-B, will be described in this chapter Its relation to HSDPA and WiMAX will be looked into

Keywords: Mobile communication; CDMA2000 1X, Channel Structure, Transmission Scheme, Call

Processing, Protocol Layers, Forward link, Reverse link, Dedicated channel, Common control channel, LAC, MAC, Engineering, Operation, Coverage, LBA, Capacity, Scheduling Strategy, QoS, LBA, Core network, IMS, EV-DO Rev A, EV-DO Rev-B, HSDPA, Mobile WiMAX

CDMA technology was first proposed by Qualcomm as the standard for the digitalcellular services in North America Then, the CDMA technology was authorized as

an IS-95 standard of the Telecommunications Industry Association (TIA) in July

1993 IS-95A revision was published in May 1995 and is the basis for many of thecommercial 2G CDMA systems around the world In addition to voice services,IS-95A provides circuit-switched data connections at 14.4 kbps The IS-95Brevision, also termed TIA/EIA-95, combines IS-95A, ANSI-J-STD-008 and TSB-74into a single document and offers up to 115kbps packet-switched data

CDMA2000 1X is an ITU-approved as 3G standard It can double voice capacity

of IS-95A networks and delivers peak packet data speeds of 153 kbps (Release 0)

or 307 kbps (Release A) in mobile environments in a single 1.25 MHz channel Toprovide higher peak data rate to subscribers, 1xEV-DO technology, which part of afamily cdma2000 1X digital wireless standards, stands for ”Evolution, Data-only”

151

Y Park and F Adachi (eds.), Enhanced Radio Access Technologies for Next Generation Mobile Communication, 151–190.

© 2007 Springer.

and delivers forward link data rate up to 2.4 Mbps in a single 1.25 MHz channel,addressing data only-not voice 1xEV-DO is based on a technology initially known

as “HDR” (High Data Rate), developed by Qualcomm and the standard is known

as IS-856

CDMA technology shares a block of spectrum through the use of a spreadingcode (pseudo-random noise or PN code), which is unique to the individual use Ittransmits data spread in a full available spectrum reducing the need to guard bandsand increasing efficiency use The CDMA technology accommodates users 10 to 20times larger than those of the AMPS using FDMA In addition, CDMA technology

is the strong to high frequency selective fading characteristics due to multiple-pathsignals So CDMA technology is suitable for areas with high user density or anurban area where high-rise buildings are concentrated

The Korean government adopted CDMA as the official standard for mobiledigital communication through the notice of the Ministry of Communication inNovember 1993 SK Telecom, a Korean cellular service provider, introducedcommercial cellular service based on IS-95A technology for the first time in theworld in 1996 And also, SK telecom commercialized CDMA2000 1x Service inOctober, 2000 and 1xEV-DO Service in February, 2002 3GPP2, the Third Gener-ation Partnership Project 2, is responsible for establishing specifications related

to the synchronization-type CDMA2000, and to keep reflecting next-generationtechnologies (MIMO and OFDM etc) regarding specifications to upgrade thedata rate

• Channel Structure

– Structure and Characteristics of Forward Link Channel

As shown Figure 1, channels for fast data transmission and control channels for

efficient signaling control have been added to the forward link in the IS-95 standard.The forward link channels are divided into the dedicated channels and common

channels The dedicated channels are used for specific users, and include a

funda-mental channel for low-speed rate transmission, a supplefunda-mental channel for fastdata transmission, and a dedicated control channel for the delivery of mobile-specific control information And also, a dedicated Auxiliary pilot channel is usedwith antenna beam-steering techniques to increase the coverage or data rate for

a particular user One common channel includes the pilot channel that measureschannel strength and supports coherent detection and hand-off Handoff is aprocedure where a mobile phone with an on-going call changes channel and/orbase station under a supervisory system Other common channels include the syncchannel that transmits data necessary for synchronization between terminal andsystem, and the paging channel that provides system information and paging infor-mation There is also the broadcast control channel added to provide broadcast

CDMA2000 1X & 1X EV-DO 153

Figure 1 1x Forward link channel structure

system-specific and cell-specific overhead data, and the quick paging channel thatimproves paging operations in slotted-mode

– Structure and Characteristics of Reverse Link Channel

The below Figure 2 shows the pilot channel, the data transmission dedicated

channel, and the improved access channel to be used to transmit moderate-sizeddata packets have been added to the reverse link in the IS-95 standard

Like the forward link channels, the reverse link channels consist of dedicatedchannels and common channels, both of which function similarly to dedicate andcommon channels in the forward link Reverse dedicated channels include thefundamental channel, the supplemental channel, the dedicated control channel,and the power control sub-channel, which transmits the power control part

Figure 2 1x Reverse link channel structure

related to reverse power control Reverse dedicated control channels are usedfor the transmission of user and signaling information to the system during

a call The reverse common channels include the access channel used by aterminal for communicating to the base station for short signaling messageexchanges, such as call originations, response to pages, and registrations, thecommon control channel used to transmit control data, an enhanced access channelthat provides improved accessibility and a pilot channel that provides a phasereference for coherent demodulation and may provide a means for signal strengthmeasurement

• Transmission Scheme and Characteristics

– Transmission Channel Structure of the Forward

Major improvements to the forward link in the CDMA2000 1X are fast powercontrol that can support up to 800Hz, increased capacity through OrthogonalTransmit Diversity (OTD), enhanced battery life by quick paging channel, anddedicated channel for fast data transmission

Figure 3 shows the transmission scheme of the 9.6kbps fundamental channel.The CRC and the tail bits are added to a data bit to create a 9.6kbps bit stream

At this time, the bit stream passes through an encoder and the interleaver forpower control puncturing And then, orthogonal spreading and complex scrambling

is made through the Walsh A long PN code scrambles the channel The rate

of scrambling code depends on the code rate of input And only PCH(PagingChannel), DCCH(Dedicated Control Channel), FCH(Fundamental Channel) andSCH(Supplemental Channel) are scrambled A Walsh code running at the chip rate(1.2288Mcps) multiplies the data The same code is used for both In-Phase andQuadrate components Each channel is assigned a different Walsh code and might

be of different lengths, to adjust to the spreading factor of the data required Thedata is then complex PN multiplied, also at the chip rate

Figure 3 9.6kbps FCH Transmission scheme

CDMA2000 1X & 1X EV-DO 155The transmission scheme of the SCH (153.6Kbps) is similar to that of the FCH.However, with 19.2Kbps or higher, the Turbo code is used for fast data transmissioninstead of a convolution code.

– Transmission Channel Structure in Reverse Link

One of the characteristics of the reverse link structure in CDMA2000 1X is that

it uses the dedicated signaling channel In IS-95, one channel is used to logicallyseparate the frame However, in the CDMA 2000 1X, a dedicated signaling channel

is used so that several Walsh codes identify channels The Walsh code applied to

the reverse link has different lengths depending on the channel as shown in Table 1 The following Figure 4 illustrates the reverse link modulation and spreading

process The channel illustrated here is the Reverse Dedicated Channel It consists

of a Reverse Pilot Channel, which is always present, an R-FCH, an R-SCH, and

an R-DCCH The reverse link uses reverse pilot, hence greatly improving detection

performance by only using the preamble As shown in Figure 4, the reverse

channels are spread by different-sized Walsh codes, and after gain scaling, the data

is transmitted to I and Q channels The gain scaling is used to apply the relative

Table 1 Walsh codes applied to reverse channel

Reverse Pilot Channel W0 32

Enhanced Access Channel W2

Reverse Common Control Channel W2

Reverse Dedicated Control Channel W8 16

Reverse Fundamental Channel W4 16

Reverse Supplemental Channel 1 W1 Or W2

Reverse Supplemental Channel 2 W2 Or W6

Figure 4 Reverse link transmission scheme

offset to each channel based on pilot channel power The spread Pilot channel andthe R-DCCH are mapped to the In-Phase components The Spread R-FCH andR-SCH are mapped to the Quadrate components.

• Call Processing

The terminal passes through the initialization state, the idle state, and the access

state to enter into the traffic state after initial power-up as shown in Figure 5.

When the user powers up the terminal, the terminal will enter into the initializationstate where the terminal brings necessary information internally stored to decide thesystem to use and to receive the pilot channel and the sync channel to synchronizewith the system In its idle state, the terminal receives all of the system informationand keeps monitoring the paging channel The terminal in its idle state transits intothe system access state through originating or receiving a call or registration andperforming a series of operations to access the system The information necessaryfor access to the system is received on the paging channel of Forward link Aftersuccessfully accessing the system, the terminal transits into the traffic state and

F – pilot CH or sync CH Paging CH or BCCH,

F – CCCH

AC H, E ACH, or R – C CC H Paging C H or F – C CC H F/R – FCH, F/R – DCCH

Unable to receive Paging Channel Message

Directed to Traffic Channel

Receives Page, Originates, or Registers

Receipt of acknowledgement

to other than Origination or Page Response message.

System Access State

Mobile Station Idle State

Figure 5 MS State transition diagram

CDMA2000 1X & 1X EV-DO 157establishes a voice call or a data communication If a call is terminated, the terminalenters into, first the initialization state and then the idle state in order.

When a terminal in a traffic state crosses the cell boundary, the terminal performs

a handoff to keep the call During the handoff process, the user’s serving cell may

be changed Major parameters used during the handoff process include Ec/Io of thebase station pilot signal strength and T_add and T_drop sent from the system to theterminal, using system parameter messages over the paging channel Pilot StrengthMeasurement Message (PSMM), the Extended Handoff Direction Message (EHDM)and the Handoff Completion Message (HCM) are the main messages relating withthe handoff With handoffs, CDMA2000 1X system supports two types of handoff;make-before-break, known as soft handoff and break-before-make, known as hard

handoff The below Figure 6 is an example about handoff procedure; T-add &

T-drop Procedure

• Protocol Layer

Figure 7shows the protocol stack of the CDMA2000 1X data In most cases, themobile network does not use all OSI 7 layers defined in ISO1 The Protocol stacksthat can be managed by CDMA2000 1X are Layers 1∼2

– Physical Layer

The physical layer manages hardware operations that are related to the transmissionbetween terminal and BTS The physical layer transmits the data coming from theMAC layer through the air through coding, modulation, spreading, and interleavingprocesses, and sends back the data coming from the air link to the upper MAC layer

Figure 6 CDMA2000 1X Handoff procedure

Figure 7 Protocol layer

– MAC Layer

The MAC layer classifies and manages (signaling and traffic) data, and performsoperations such as multiplexing, Radio Link Protocol (RLP), and Quality of Service(QoS) The MAC layer properly allocates resources that various entities2 need andprocesses them for each media The RLP, one of the major protocols at the MAClayer, is used to prevent errors in the wireless node The MAC also defines how toprocess the physical layer in sync channels, paging channels, access channels, andthe common control channels

– LAC Layer

The LAC layer is an upper layer of the MAC layer, and manages operations forcontrol, signals and data or voice communication that is the ultimate goal of traffic.The LAC layer is applied only to signaling, not to general (data or voice) traffic.The LAC layer is divided into five sub layers, and processes various operationsincluding authentication, delivery, addressing, message identification, and CRCprocessing

• Channel Structure and Characteristics

– Structure and Characteristics of Forward Link Channels

The forward link channel of 1xEV-DO has been created based on the HDR ofQualcomm that supports 2.4Mbps of high data transmission The transmission