3G Mobile Cellular Technologies

3G Mobile Cellular Technologies
The great success of mobile cellular communication systems is probably one of the most celebrated
events in the history of the telecommunication industry over the past 100 years. The convenience of
mobile cellular telephony has finally made a dream come true: people can get in touch with anyone
else on earth at any time and at any place. The modern microelectronics industry has made it possible
to produce a cell phone is small enough to be carried in a pocket, to put on a necklace, or even to
be worn as a watch. In fact, it is hard to imagine the outcome if all mobile cellular services around
us disappeared.
Mobile cellular systems have been developed over three key generations. The services of the
first generation (1G) systems began when analogue technology-based mobile telephony was first
introduced in Chicago City in the 1980s. This 1G analogue mobile cellular system in the United States
is also called Advanced Mobile Phone System (AMPS) system [316], which operated in 800 MHz
and used 30 kHz bandwidth under the frequency division multiple access (FDMA) scheme. There
are several other 1G systems which were in service in other countries/regions, such as Total Access
Communications System (TACS) in the United Kingdom, the Nordic Mobile Telephone (NMP) in the
Scandinavian countries, and so on. The common characteristic features for all 1G systems around the
world can be summarized as follows. First, they operated in the FDMA scheme, in which all voice
channels are separated by different frequency carriers with a relatively narrow bandwidth (usually
about 30–50 kHz). Second, they were based on analogue transmission and processing technologies.
Third, each system only covered a country or a relatively small region. Finally, the capacity of all
those 1G mobile cellular systems was small due to their low bandwidth efficiency. Different 1G
mobile cellular systems or standards are listed in Table 3.1, and brief descriptions of all 1G mobile
cellular systems or standards are given in Table 3.2.
The characteristic features of the 1G mobile cellular systems have motivated the research and
development of the second generation (2G) mobile cellular standards, mainly initiated by two different
groups, one in the United States and the other in Europe.
The 2G systems proposed by the United States took two different approaches, one leading to a
new Time Division Multiple Access (TDMA) based technology, digital AMPS (D-AMPS) standard
(the IS-54B and its enhanced version, IS-136 standard); and the other using the Code Division
Multiple Access (CDMA) technology, the IS-95 standard [317–344]. The D-AMPS was designed to
be compatible with the earlier analog AMPS technology, which was widely deployed in the United
States. TDMA is used as an enhancement to the AMPS network by the use of dual-band AMPS/TDMA
(or D-AMPS) phones. Use of these phones gives the widespread coverage of the AMPS networks
along with some advantages of digital systems in the areas where TDMA networks are available. On Table 3.1 The 1G mobile cellular systems or standards worldwide
System or standard Service start date Country of origin or
region it operated
AMPS 1979 trial, 1983
commercial
United States, then worldwide
AURORA-400 1983 Alberta, Canada
C-Netz and C-Netz C-450 Begins in 81, upgraded in
1988
Germany, Austria, Portugal,
South Africa
Comvik August, 1981 Sweden
ETACS 1987 United Kingdom, now
worldwide
JTACS June, 1991 Japan
N-AMPS (Narrowband Advanced
Mobile Phone Service)
1993 United States, Israel
NMT 450 1981 Sweden, Norway, Denmark
NMT 900 1986 Finland, Oman; NMT exists
in 30 countries
NTACS/JTACS June, 1991 Japan
NTT December, 1979 Japan
NTT Hi Cap December, 1988 Japan
RadioCom (RadioCom2000) November, 1985 France
RTMS (Radio Telephone Mobile
System)
September, 1985 Italy
TACS (Total Access
Communications System)
1985 United Kingdom, Italy, Spain,
Austria, Ireland
the other hand, the IS-95 standard proposed by Qualcomm Inc. is based on CDMA technology and
offers numerous new capabilities that the former multiple access technologies, such as TDMA and
FDMA, can never possess.
At almost the same time, Europe proposed a pan-European 2G mobile phone standard, Group
Special Mobile which was later called Global System for Mobile Communications (GSM), in order
to bring the same standard to all major European countries under the strong leadership of European
Telecommunications Standards Institute (ETSI), an agency based in Sophia Antipolis, in the south
of France. This was first undertaken by the European Commission (EC) and later by the European
Union (EU). The GSM system uses TDMA technology and can operate in three different bands
(800 MHz, 900 MHz and 1.8 GHz) around the world. The very different marketing approaches used
by Europe has made the GSM system the single most popular digital mobile cellular system in the
world today, and its worldwide subscribers have reached nearly 0.3 billion, according to the latest
statistics. Without a doubt, the GSM is the most popular 2G mobile cellular system if measured by
its market share in the world.
In addition to the IS-54B, IS-136 and GSM standards, there are many other 2G wireless and
cordless digital telephone systems that have been proposed and adopted by different countries and
regions in the world. Their major characteristics and brief descriptions have been given in Table 3.3.
The evolution of mobile cellular telephone systems from 1- to 2G has clearly indicated that the
Americans were very successful in the development and application of the 1G analog system, AMPS
system, not only in North America but also in many other regions in the world. Although the United
States was still technologically dominant in 2G mobile cellular systems, Europe was the final winner
to grasp the largest mobile cellular market share in the world, that is manifested in the number Table 3.2 Main Features of the 1G mobile cellular systems or standards worldwide
AMPS Advanced Mobile Phone System. Developed by Bell Labs in the 1970s and first used
commercially in the United States in 1983. It operates in the 800- and 1900 MHz
band in the United States and is the most widely distributed analog cellular standard.
Close to being defunct.
C-450 Installed in South Africa during the 1980s. Almost like C-Netz. Now known as
Motorphone System 512 and run by Vodacom SA.
C-Netz Older cellular technology found mainly in Germany and Austria. Operates at 450 MHz.
May no longer be working.
Comvik Launched in Sweden in August 1981 by the Comvik network, lasted until March 31,
1996.
N-AMPS Narrowband Advanced Mobile Phone System. Developed by Motorola as an interim
technology between Analog and digital. It has some 3 times greater capacity than
AMPS and operates in the 800 MHz range. Now defunct.
NMT450 Nordic Mobile Telephones/450. Developed specially by Ericsson and Nokia to service
the rugged terrain that characterises the Nordic countries. The first multinational
celllullar network. Operates at 450 MHz.
NMT900 Nordic Mobile Telephones/900. The 900 MHz upgrade to NMT 450 developed by the
Nordic countries to accommodate higher capacities and handheld portables.
NMT-F French version of NMT900.
NTT Nippon Telegraph and Telephone. The old Japanese Analog standard. A high-capacity
version is called HICAP.
RC2000 Radiocom 2000. French system launched November 1985.
TACS Total Access Communications System. Developed by Motorola. and is similar to
AMPS. It was first used in the United Kingdom in 1985, although in Japan it is
called JTAC. It operates in the 900 MHz frequency range.
Table 3.3 Brief description of the 2G mobile cellular systems or standards worldwide
A1-Net Austrian Name for GSM 900 networks.
CDMA Code Division Multiple Access. IS-95. Developed by Qualcomm, characterized by
high capacity and small cell radius. It uses the same frequency bands as AMPS and
supports AMPS operation, employing spread-spectrum technology and a special
coding scheme. It was adopted by the Telecommunications Industry Association
(TIA) in 1993. The first CDMA-based networks are now operational.
cdmaOne Wide ranging wireless specification involving IS-95, IS-96, IS-98, IS-99, IS-634 and
IS-41. AT&T, Motorola, Lucent, ALPS, GSIC, Prime Co, Qualcomm, Samsung,
Sony, United States West, Sprint, Bell Atlantic, and Time Warner are sponsors.
CDPD Cellular digital packet data. Overlays existing cellular networks to provide faster data
transfer. Bell Atlantic Mobile offers it in the New York metropolitan area, New
Jersey, Connecticut, Massachusetts, Pittsburgh, the greater Philadelphia area, the
Washington and Baltimore metropolitan areas, and North and South Carolina.
CT-2 A second generation digital cordless telephone standard. CT2 has 40 carriers × 1
duplex bearer per carrier = 40 voice channels. Supposedly withdrawn in Canada.
CT-3 A third generation digital cordless telephone, which is very similar and a precursor to
DECT.
D-AMPS Digital AMPS. Designed to use existing channels more efficiently, D-AMPS (IS-136)
employs the same 30 kHz channel spacing and frequency bands (824–849 and
869–894 MHz) as AMPS. By using TDMA instead of FDMA, IS-136 increases
the number of users from 1 to 3 per channel. An AMPS/D-AMPS infrastructure
can support either an Analog AMPS phone or digital AMPS phones. (The Federal
Communications Commission mandated that digital cellular in the United States
must act in a dual-mode capacity with analog). Operates in the 800- and
1900 MHz bands.
DCS DCS also stands for Digital Communications Systems, another word for American
GSM.
DECT Digital European Cordless Telephony. This started off as Ericsson’s CT-3, but
developed into the ETSI Digital European Cordless Standard. It is intended to be a
far more flexible standard than the CT2 standard, in that, it has more RF channels
(10 RF carriers × 12 duplex bearers per carrier = 120 duplex voice channels). It
also has better multimedia performance since 32 kbit/s bearers can be
concatenated. Ericsson is developing a dual GSM/DECT handset that will be
piloted by Deutsche Telekom.
E-Netz The German name for GSM 1800 networks.
GSM Global System for Mobile Communications. The first European digital standard,
developed to establish cellular compatibility throughout Europe. Its success has
spread to all parts of the world and over 80 GSM networks are now operational. It
operates at 900- and 1800 MHz in many parts of Europe and in England. Works at
1900 MHz in some parts of the United States. TDMA-based. See below.
PCS Personal Communications Service. The PCS frequency band in the United States is
1850- to 1990 MHz, encompassing a wide range of new digital cellular standards
like N-CDMA and GSM 1900. Singleband GSM 900 phones cannot be used on
PCS networks. PCS networks operate throughout the United States.
IS-54 TDMA-based technology used by the D-AMPS system at 800 MHz.
IS-95 CDMA-based technology used at 800 MHz.
IS-136 TDMA-based technology offered at both 800- and 1800 MHz. Should be referred to
as cellular. AT&T’s choice to offer PCS like services.
JS-008 CDMA-based standard for 1900 MHz.
Nextel Direct connect service offers point to point communication as well as a TDMA-based
cellular telephone in a single handset.
PDC Personal Digital Cellular is a TDMA-based Japanese standard operating in the 800-
and 1500 MHz bands.
PHS Personal Handy System. A Japanese-centric system that offers high-speed data
services and good voice clarity.
TDMA Time Division Multiple Access. The first U.S. digital standard to be developed. It
was adopted by the TIA in 1992. The first TDMA commercial system began in
1993. Called IS-54 at first and now known as IS-136.
TETRA Trans European Trunked Radio Systems, designed to support both voice and data.
Very new. Mostly used in trucks. Allows roaming. Not yet fully implemented.
of worldwide GSM system subscribers. Under these circumstances, Europe, which was enjoying a
great amount of benefit from technological transfer as well as 2G-related equipments sales (even
today), was not in a hurry to push for the third generation (3G) mobile communication systems. In
the meantime, Japan captured little market share in the worldwide 1- to 2G mobile cellular business,
partly due to its long time conservative telecommunication policies and regulations and partly to its
unique 2G mobile cellular systems, which were incompatible to the others. Japan’s urgent desire to
join Europe in developing 3G mobile communication systems was also motivated by its technical
competition with Korea, which acquired key CDMA technologies from Qualcomm in the mid 1990s
and was able to develop and manufacture its own CDMA-based mobile telephone systems in the
late 1990s. Seen from Japan’s point of view it seemed to be completely unacceptable if it were
to lag behind Korea in CDMA-based mobile communication technologies. Therefore, it has to be
acknowledged that Japan played an important role in the development of the current 3G mobile
communication standards, especially the WCDMA standard proposed by the Association of Radio
Industries and Business (ARIB) of Japan and the Universal Mobile Telephone System (UMTS)
standard proposed by ETSI.
On the other hand, the initiation of the 3G mobile communication systems should also be
attributed to the active involvement of the International Telecommunications Union (ITU), a special
technical agency under the United Nations (UN) in the year 2000. The initiative program was
Table 3.4 The comparison of major physical layer parameters of TD-SCDMA, WCDMA, and
CDMA2000 standards
Parameters CDMA2000 WCDMA TD-SCDMA
Multiple access DS-CDMA/MC-CDMA DS-CDMA TDMA/DS-CDMA
CLPCF 800 Hz 1600 Hz 200 Hz
PCSS 0.25, 1.5 dB 0.25, 0.5, 1.0 dB 1, 2, 3 dB
Channel coding Convolutional or Turbo Convolutional, RS or
Turbo
Convolutional or
Turbo
Spreading code DL: Walsh, UL: M-ary
Walsh
OVSF OVSF
VSF 4· · · 256 4· · · 256 1· · · 16
Carrier 2 GHz 2 GHz 2 GHz
Modulation DL: QPSK, UL: BPSK DL: QPSK, UL: BPSK QPSK, 8PSK
(2 Mbps)
Bandwidth 1.25*2/3.75*2 MHz 5*2 MHz 1.6 MHz
UL-DL spectrum paired paired unpaired
Chip rate 1.2288/3.6864 Mcps 3.84 Mcps 1.28 Mcps
Frame length 20 ms, 5 ms 10 ms 10 ms
Interleaving periods 5/20/40/80 ms 10/20/40/80 ms 10/20/40/80 ms
Maximum data rate 2.4 Mbps 2 Mbps (low mobility) 2 Mbps
Pilot structure DL: CCMP, UL: DTMP DL: DTMP, UL: DTMP CCMP
Detection PSBC PCBC PSBC
Inter-BS timing Synchronous Asynchronous/
Synchronous
Synchronous
CCMP: common channel multiplexing pilot DTMP: dedicated time multiplexing pilot
VSF: Variable spreading factor CLPCF: Close loop power control frequency
PCSS: Power control step size DL: downlink
PSBC: Pilot symbol
called International Mobile Telephony (IMT-2000), which aimed to put forward a unified worldwide
standard that allowed people the use of only one handphone for any place. Although this original
objective of the ITU was not fulfilled, the numerous 3G mobile communication proposals submitted
by different countries and regions laid the solid foundation for the development of all current
major 3G standards, such as WCDMA [431], UMTS UTRA [425], CDMA2000 [345], TD-SCDMA
[432, 433], and so on. The basic technical parameters for three major 3G standards, that is, WCDMA,
CDMA2000 and TD-SCDMA, are compared in Table 3.4.
In this chapter we are limited to discussing several major 3G standards, such as CDMA2000,
WCDMA, UTRA-FDD, UTRA-TDD, and TD-SCDMA systems. However, it is to be noted that
the discussions on 3G wireless communication technologies/standards given in this chapter should
not be considered as a complete collection of all those standards. We can only offer a general
description for each of them by focusing on the most important aspects of the standards concerned.
For more comprehensive coverage of the technical details of those standards, readers may check
http://www.3gpp.org/ and http://www.3gpp2.org/, which provide the most authoritative and up-todate
information of all those major standards. Finally, we are particularly thankful to the generosity
of 3GPP and 3GPP2 to allow us free access to their important standards documentations.
CDMA2000
Before we start to talk about the CDMA2000 standard, it will be beneficial to take a brief look at
the historical background of worldwide 3G mobile cellular systems. The third generation wireless
is a term used to describe next generation mobile services, which provide better quality voice and
high-speed Internet and multimedia services. In contrast, the 2G systems (such as IS-95, GSM, etc.)
were basically oriented toward voice-centric applications. While there are many interpretations of
what 3G represents, the only universally accepted definition is the one published by the ITU [308],
which defines and approves technical requirements and standards, as well as the use of spectra
for 3G systems under the IMT-2000 (International Telecommunication Union-2000) program [308].
The ITU requires that IMT-2000 (3G) networks, among other capabilities, deliver improved system
capacity and spectrum efficiency over the 2G systems and support data services at the minimum
transmission rates of 144 kbps in mobile (outdoor) and 2 Mbps in fixed (indoor) environments. Based
on these requirements, the ITU approved five candidate radio interfaces for IMT-2000 standards in
1999 as a part of the ITU-R M.1457 Recommendation. CDMA2000 is one of the five standards. It is
also known by its ITU name, or IMT-CDMA Multi-carrier. The five radio interfaces for IMT-2000
standards approved by ITU in 1999 as a part of the ITU-R M.1457 Recommendation include:
• IMT-2000 CDMA Direct Spread (also called WCDMA-UMTS)
• IMT-2000 CDMA Multi-carrier (also called CDMA2000 1x and 1xEV )
• IMT-2000 CDMA TDD (also called UTRA-TDD and TD-SCDMA)
• IMT-2000 TDMA Single Carrier (also called UWC-136/EDGE)
• IMT-2000 FDMA/TDMA (also called DECT)
All of the five approved 3G standards have become important technical standards developed by
different countries or regions. The WCDMA-UMTS was jointly proposed by ARIB, Japan, and ETSI,
Europe; the CDMA2000 was proposed by Telecommunications Industry Association (TIA)/EIA of
the United States; the UTRA-TDD was proposed by ETSI of Europe and TD-SCDMA was proposed
by CATT of China, respectively. UWC-136/EDGE was also proposed by TIA/EIA of the United
States, and finally, DECT was proposed by ETSI of Europe.
With this background knowledge about the development of worldwide 3G standards, we would
like to come back to the topic of interest in this section, or CDMA2000 [345], which is a direct
evolution from cdmaOne technology and provides a set of specifications that offer enhanced voice
and data capacity. The CDMA2000 family includes: CDMA2000 1x, CDMA2000 1xEV-DO and
CDMA2000 1xEV-DV standards. CDMA2000 is also known as IS-2000.
CDMA2000 1x (which once carried many other names, such as CDMA2000 phase 1, 1xRTT,
3G CDMA 1x, etc.) is commonly referred to as 1x or sometimes as 1x RTT. CDMA2000 1x is a 3G
technology that is commercially available today and is 21 times more efficient than analog cellular
networks and 4 times more efficient than TDMA networks. Typical CDMA2000 1x networks provide
peak rates of 144 kbps for packet data and an average throughput range of 60–90 kbps on a loaded
network. It doubles the voice capacity of cdmaOne networks and delivers peak packet data speeds of
307 kbps in mobile environments.
CDMA2000 1xEV1 includes the two directive technologies, CDMA2000 1xEV-DO [346]2 and
CDMA2000 1xEV-DV [347]3. In fact, the 1xEV name, which stands for “Evolution” was coined in
the standards process. The standard was balloted and adopted by 3GPP2, as C.S0024 [361–367], and
by TIA/EIA, as IS-856, in October 2000.
1xEV-DO [346] is the short form of “First Evolution,” “Data Optimized.” CDMA2000 1xEV-DO
provides peak data rates of up to 2.4 Mbps in a standard 1.25 MHz channel used exclusively for data.
1xEV-DO provides an average throughput of over 700 kbps, equivalent to cable modem speeds, and
fast enough to support applications such as streaming video and large file downloads, and so on.
Future releases will increase to 3.08 Mbps for the forward link.
1xEV-DV [347] is the short form of “1x Evolution, Data and Voice.” The CDMA2000 1xEV-DV
standard is still under development and is expected to be deployed commercially in late 2005 or
early 2006. CDMA2000 1xEV-DV can support voice as well as data. Release C of the CDMA2000
1xEV-DV standard supports a forward link of 3.08 Mbps and a reverse link of 153 kbps. Release D
supports a forward link of 3.08 Mbps and a reverse link of approximately 1.0 Mbps.
Both CDMA2000 1xEV-DO and CDMA2000 1xEV-DV are backward compatible with
CDMA2000 1x and cdmaOne. The CDMA2000 1xEV (also known as High Data Rate (HDR) technology
or IS-856) working group was established in 3GPP2, TSG-C in March 2000.
The world’s first CDMA2000 1x commercial system was launched by SK Telecom (Korea) in
October 2000. Since then, CDMA2000 1x has been deployed in Asia, North and South America, and
Europe, and the subscriber base is growing at 700,000 subscribers per day. CDMA2000 1xEV-DO was
launched in 2002 by SK Telecom and KT Freetel. There are already more than 12 million 1xEV-DO
users today, with some more networks expected to be launched this year (2005) and the next. The commercial
success of CDMA2000 has made the IMT-2000 vision a reality. The milestones of development
and deployment of CDMA2000 systems in the world is tabulated in Table 3.5. The CDMA2000
subscriber growth history from March 2001 through December 2004 is shown in Figure 3.1.
3.1.1 Operational Advantages
CDMA2000 benefited from the extensive experience acquired through several years of operation of IS-
95 or cdmaOne systems. As a result, CDMA2000 is more efficient and robust than its predecessor, IS-
95 systems. Supporting both voice and data, the standard was devised and tested in various spectrum
bands, including the new IMT-2000 allocations. There is tremendous demand for new services and
operators are to provide these to many more subscribers at reasonable prices. The unique features, benefits,
and performance of CDMA2000 make it a mature technology for high-voice capacity and highspeed
packet data. The fact that CDMA2000 1x has the ability to support both voice and data services
Table 3.5 The Milestones for CDMA2000 system development and deployment worldwide
Time Events
Aug 2004 Eurotel Praha (Czech Republic) launches the world’s first CDMA2000 1xEV-DO
network at 450 MHz (CDMA450)
June 2004 100 million commercial CDMA2000 subscribers
April 2004 CDMA2000 1xEV-DO Revision A approved by Third Generation Partnership
Project 2 (3GPP2)
March 2004 5 million commercial CDMA2000 1xEV-DO subscribers
March 2004 CDMA2000 1xEV-DV Revision D approved by Third Generation Partnership
Project 2 (3GPP2)
Oct 2003 Verizon Wireless (United States) launches the first CDMA2000 1xEV-DO service
in North America
May 2003 1 million commercial CDMA2000 1xEV-DO subscribers
May 2003 50 million commercial CDMA2000 subscribers
April 2003 Vesper (Brazil) launches the first CDMA2000 1xEV-DO network in Latin America
Sept 2002 Pelephone Communications Ltd. (Israel) launches the first CDMA2000 1x network
in Africa–Middle East region
June 2002 Third Generation Partnership Project 2 (3GPP2) and Telecommunications Industry
Association (TIA) approve CDMA2000 1xEV-DV (Data Voice) for publication
May 2002 10 million commercial CDMA2000 subscribers
Jan 2002 SK Telecom (Korea) launches the world’s first CDMA2000 1xEV-DO network
Dec 2001 VIVO (Brazil) launches the first CDMA2000 1x network in Latin America
Dec 2001 Telemobil (Romania) launches the world’s first CDMA2000 network at 450 MHz
(CDMA450)
Aug 2001 1 million commercial CDMA2000 subscribers
July 2001 Western Wireless (United States) deploys the first CDMA2000 1x network in North
America
June 2001 ITU recognizes CDMA2000 1xEV-DO as part of the 3G IMT-2000 standard
Oct 2000 SK Telecom and LG Telecom (South Korea) launch the world’s first 3G
commercial CDMA2000 networks
Nov 1999 ITU-R Task Group 8/1 endorses CDMA2000 standards (three modes) for IMT-2000
July 1999 Phase 1 CDMA2000 standard complete and approved for publication
on the same carrier makes it cost-effective for wireless operators. Because of its optimized radio technology,
CDMA2000 enables operators to invest in fewer cell sites and deploy them faster, allowing
the service providers to increase their revenues with faster Return On Investment (ROI). Increased
revenues, along with a wider array of services, make CDMA2000 the technology of choice for service
providers. The major operational advantages of CDMA2000 are summarized in the subsequent text.
Increased voice capacity
Voice is the major source of traffic and revenue for wireless operators, but packet data will emerge
as an important source of incremental revenue in the years to come. CDMA2000 delivers high-voice
capacity and packet data throughput using a relatively small amount of spectrum for a lower cost.
CDMA2000 1x supports 35 traffic channels per sector per RF (26 Erlangs/sector/RF) using the
EVRC vocoder,4 which became commercial in 1999.
Voice capacity improvement in the forward link is attributed to faster power control, lower code
rates (1/4 rate), and transmit diversity (for single path Rayleigh fading). In the reverse link, capacity
improvement is primarily due to coherent reverse link.
Higher data throughput
Today’s commercial CDMA2000 1x networks (phase 1) support a peak data rate of 153.6 kbps.
CDMA2000 1xEV-DO, which has been commercialized in Korea, enables peak rates of up to
2.4 Mbps and CDMA2000 1xEV-DV will be capable of delivering data of 3.09 Mbps.
Frequency band flexibility
CDMA2000 can be deployed in all cellular and PCS spectrums, as shown in Figure 3.15. CDMA2000
networks have already been deployed in the 450 MHz, 800 MHz, 1700 MHz, and 1900 MHz bands;
deployments in 2100 MHz and other bands are expected in 2004–2005. CDMA2000 can also be
implemented in other frequencies such as 900 MHz, 1800 MHz and 2100 MHz. The high spectral
efficiency of CDMA2000 permits high traffic deployments in any 1.25 MHz channel of spectrum.
Increased battery life
CDMA2000 enhances battery performance. Benefits include: (1) Quick paging channel operation
with improved reverse link performance; (2) New common channel structure and operation; (3)
Reverse link gated transmission; and (4) New Medium Access Control (MAC) states for efficient and
ubiquitous idle time operation.
Synchronization
CDMA2000 is synchronized with the Universal Coordinated Time (UCT). The forward link
transmission timing of all CDMA2000 base stations worldwide is synchronized within a few
microseconds. Base station synchronization can be achieved through different techniques including
self-synchronization, radio beep, or through satellite-based systems such as GPS, Galileo, or
GLObal NAvigation Satellite System (GLONASS).5 Reverse link timing is based on the received
timing derived from the first multipath component used by the terminal.
There are several benefits to having all the base stations in a network synchronized. First, the
common time reference improves the acquisition of channels and handoff procedures since there is no
time ambiguity when looking for and adding a new cell in the active set. Second, it also enables the
system to operate some of the common channels in soft handoff, which improves the efficiency of the
common channel operation. Third, the common network time reference allows the implementation of
very efficient position location techniques.
Power control
The CDMA2000 basic frame length is 20 ms that is divided into 16 equal power control groups. In
addition, CDMA2000 defines a 5 ms frame structure, essential for the support of signaling bursts,
as well as 40 and 80 ms frames, which offer additional interleaving depth and diversity gains for
data services. Unlike IS-95 where Fast Closed-Loop Power Control was applied only to the reverse
link, CDMA2000 channels can be power controlled at up to 800 Hz in both the reverse and forward
links. The reverse link power control command bits are punctured into the F-FCH or the F-DCCH
(explained in later sections) depending on the service configuration. The forward link power control
command bits are punctured in the last quarter of the R-PICH power control slot.
In the reverse link, during gated transmission, the power control rate is reduced to 400 or 200 Hz
on both links. The reverse link power control subchannel may also be divided into two independent
power control streams, either both at 400 bps, or one at 200 bps and the other at 600 bps, allowing
for the independent power control of forward link channels.
In addition to the closed-loop power control, the power on the reverse link of CDMA2000 is also
controlled through an Open Loop Power Control mechanism. This mechanism inverses the slow fading
effect due to path loss and shadowing. It also acts as a safety fuse when the fast power control fails.
When the forward link is lost, the closed-loop reverse link power control is “freewheeling” and the
terminal disruptively interferes with neighboring. In such a case, the open loop reduces the terminal
output power and limits the impact to the system. Finally, the Outer Loop Power drives the closed-loop
power control to the desired set point based on error statistics that it collects from the forward link or
reverse link. Because of the expanded data rate range and various QoS requirements, different users
will have different outer loop thresholds; thus, different users will receive different power levels at
the base station. In the reverse link, CDMA2000 defines some nominal gain offsets based on various
channel frame format and coding schemes. The remaining differences will be corrected by the outer
loop itself.
Soft handoff
Even with dedicated channel operation, the terminal keeps searching for new cells as it moves across
the network. In addition to the active set, neighbor set, and remaining set, the terminal also maintains
a candidate set.
When a terminal is traveling in a network, the pilot from a new BTS (P2) strength exceeds the
minimum threshold TADD for its addition in the active set. However, initially, its relative contribution
to the total received signal strength is not sufficient and the terminal moves P2 to the candidate set.
The decision threshold for adding a new pilot to the active set is defined by a linear function of signal
strength of the total active set. The network defines the slope and cross point of the function. When
the strength of P2 is detected to be above the dynamic threshold, the terminal signals this event to the
network. The terminal then receives a handoff direction message from the network, requesting the
addition of P2 in the active set. The terminal now operates in soft handoff.
The strength of serving BTS (P1) drops below the active set threshold, meaning P1 contribution
to the total received signal strength does not justify the cost of transmitting P1. The terminal starts a
handoff drop timer. The timer expires and the terminal notifies the network that P1 dropped below
the threshold. The terminal receives a handoff message from the network, moving P1 from the active
set to the candidate set. P1 strength then drops below TDROP and the terminal starts a handoff drop
timer, which expires after a set time. P1 is then moved from the candidate set to the neighbor set.
This step-by-step procedure with multiple thresholds and timers ensures that the resource is only used
when it is beneficial to the link, and pilots are not constantly added and removed from the various
lists, therefore limiting the associated signaling.
In addition to intrasystem and intrafrequency monitoring, the network may direct the terminal
to look for base stations on a different frequency or a different system. CDMA2000 provides a
framework to the terminal in support of the interfrequency handover measurements consisting of
identity and system parameters to be measured. The terminal performs required measurements as
allowed by its hardware capability.
In the event of a terminal having dual receiver structure, the measurement can be done in parallel.
When a terminal has a single receiver, the channel reception will be interrupted when performing
the measurement. In this instance, a certain portion of a frame will be lost during the measurement.
To improve the chance of successful decoding, the terminal is allowed to bias the FL power control
loop and boost the RL transmit power before performing the measurement. This method increases
the energy per information bit and reduces the risk of losing the link in the interval. Based on
measurement reports provided by the terminal, the network then decides whether or not to handoff
a given terminal to a different frequency system. It does not release the resource until it receives
confirmation that the handoff was successful or the timer expires. This enables the terminal to come
back in case it could not acquire the new frequency or the new system.
Transmit diversity
Transmit diversity consists of de-multiplexing and modulating data into two orthogonal signals, each
of them transmitted from a different antenna at the same frequency. The two orthogonal signals
are generated using either Orthogonal Transmit Diversity (OTD) or Space-Time Spreading (STS).
The receiver reconstructs the original signal using the diversity signals, thus taking advantage of the
additional space and/or frequency diversity.
Another transmission option is directive transmission. The base station directs a beam toward a
single user or a group of users in a specific location, thus providing space separation in addition to
code separation. Depending on the radio environment, transmit diversity techniques may improve the
link performance by up to 5 dB.
Voice and data channels
The CDMA2000 forward traffic channel structure (FTC) may include several physical channels:
• The Fundamental Channel (F-FCH) is equivalent to functionality Traffic Channel (TCH) for
IS-95. It can support data, voice, or signaling multiplexed with one another at any rate from
750 bps to 14.4 kbps.
• The Supplemental Channel (F-SCH) supports high-rate data services. The network may schedule
transmission on the F-SCH on a frame-by-frame basis, if desired.
• The Dedicated Control Channel (F-DCCH) is used for signaling or bursty data sessions. This
channel allows the sending of signaling information without any impact on the parallel data
stream.
The reverse TCH structure is similar to the forward TCH. It may include a Paging Indicator
Channel (R-PICH), a Fundamental Channel (R-FCH), and/or a Dedicated Control Channel (R-DCCH),
and one or several Supplemental Channels (R-SCH). Their functionality and encoding structure is the
same as that of the forward link with data rates ranging from 1 kbps to 1 Mbps.6
Traffic channel
The TCH structure and frame format is very flexible in CDMA2000. In order to limit the signaling
load that would be associated with a full frame format parameter negotiation, CDMA2000 specifies
a set of channel configurations. It defines a spreading rate and an associated set of frames for each
configuration.
The FTC always includes either a fundamental channel or a dedicated control channel. The main
benefit of this multichannel forward traffic structure is the flexibility to independently set up and tear
down new services without any complicated multiplexing reconfiguration or code channel juggling.
The structure also allows different handoff configurations for different channels. For example, the
F-DCCH, which carries critical signaling information, may be in soft handoff, while the associated
F-SCH operation could be based on a best cell strategy.
Supplemental channels
One of the key CDMA2000 1x features is its ability to support both voice and data services on the
same carrier. CDMA2000 operates at up to 16 or 32 times the FCH rate (also referred to as 16x or
32x in Release 0 and A, respectively). In contrast to voice calls, the traffic generated by packet data
calls is bursty, with small durations of high traffic separated by larger durations of no traffic. It is
very inefficient to dedicate a permanent traffic channel to a packet data call. This burstiness impacts
the amount of available power to the voice calls, possibly degrading their quality if the system is
not engineered correctly. Hence, a key CDMA2000 design issue is to ensure that a CDMA channel
carrying voice and data calls do so simultaneously with negligible impact to the QoS of both.
Supplemental Channels (SCHs) can be assigned and de-assigned at any time by the base station.
The SCH has the additional benefit of improved modulation, coding, and power control schemes. This
allows a single SCH to provide a data rate of up to 16 FCH in CDMA2000 Release 0 (or 153.6 kbps
for Rate Set 1 rates), and up to 32 FCH in CDMA2000 Release A (or 307.2 kbps for Rate Set 1
rates). Note that each sector of a base station may transmit multiple SCHs simultaneously if it has
sufficient transmit power and Walsh codes. The CDMA2000 standard limits the number of SCHs a
mobile station can simultaneously support to two. This is in addition to the FCH or DCCH, which are
set up for the entire duration of the call since they are used to carrying signaling and control frames
as well as data. Two approaches are possible: (1) individually assigned SCHs, with either finite or
infinite assignments, or (2) shared SCHs with infinite assignments.
For bursty and delay-tolerant traffic, assigning a few scheduled big pipes is preferable to dedicating
many thin or slow pipes. The big-pipe approach exploits variations in the channel conditions of
different users to maximize sector throughput. The more sensitive the traffic becomes to delay, such
as voice, the more appropriate the dedicated traffic channel (DTCH) approach becomes.
Turbo coding
CDMA2000 provides the option of using either turbo or convolutional coding on the forward and
reverse SCHs. Both coding schemes are optional for the base station and the mobile station, and the
capability of each is communicated through signaling messages prior to the set up of the call. In
addition to peak rate increase and improved rate granularity, the major improvement to the traffic
channel coding in CDMA2000 is the support of turbo coding at rate 1/2, 1/3, or 1/4. The turbo code
is based on 1/8 state parallel structure and can only be used for supplemental channels and frames
with more than 360 bits. Turbo coding provides a very efficient scheme for data transmission and
leads to better link performance and system capacity improvements. In general, turbo coding provides
a performance gain in terms of power savings over convolutional coding. This gain is a function of
the data rate, with higher data rates generally providing more turbo coding gain.
In the following subsections, we present a brief introduction to the technical aspects of the
CDMA2000 standard. In order to make up-to-date and consistent discussions throughout this section,
we concentrate on CDMA2000 1xEV (or IS-856) standard based mainly on the specifications given
in the following standard documentations [360, 361]:
• CDMA2000 High Rate Packet Data Air Interface Specification, 3GPP2 C.S20024 v2.0, October
2000.
• CDMA2000 High Rate Packet Data Air Interface Specification, 3GPP2 C.S20024-A, v1.0,
March 2004.
The former is known as Release 0 and the latter Revision A of CDMA2000 1xEV or IS-856 standard.
There are also numerous references on CDMA2000 1xEV and their evolutional versions CDMA2000
1xEV-DO and CDMA2000 1xEV-DV, and readers may refer to [360–367] for more information about
them. In particular, the recent issue (April 2005) of IEEE Communications Magazine published a
Special Issue on CDMA2000 1xEV-DV and seven papers appear in this issue [368–374], which
indicate that the CDMA2000 1xEV-DV will gain greater popularity around the world.
However, we also refer to CDMA2000 1x standard from time to time in the discussions on
CDMA2000 1xEV technology. Therefore, to understand the CDMA2000 1xEV, it is strongly recommended
that readers gain sufficient background knowledge about CDMA2000 1x standard. Release
0 of CDMA2000 1x standard [348–353] consists of the following 3GPP2 documents:
• C.S0001-0 Introduction to CDMA2000 Standards for Spread Spectrum Systems
• C.S0002-0 Physical Layer Standard for CDMA2000 Spread Spectrum Systems
• C.S0003-0 Medium Access Control (MAC) Standard for CDMA2000 Spread Spectrum Systems
• C.S0004-0 Signaling Link Access Control (LAC) Standard for CDMA2000 Spread Spectrum
Systems
• C.S0005-0 Upper Layer (Layer 3) Signaling Standard for CDMA2000 Spread Spectrum Systems
• C.S0006-0 Analog Signaling Standard for CDMA2000 Spread Spectrum Systems
Readers can find all the final revisions (or Revision D) of the CDMA2000 1x standard from the
reference list [359] provided at the end of this book.
General Architecture
The technical requirements contained in CDMA2000 standard [348–353] form a compatibility standard
for the 800 MHz cdmaOne (or IS-95A/B) system and the 1.8 to 2.0 GHz CDMA Personal Communications
Services (PCS) systems, also called JSTD-008 systems. It is required that a mobile station
can obtain service in a cellular or PCS system manufactured in accordance with the CDMA2000 standards.
The requirements do not address the quality or reliability of that service, nor do they cover
equipment performance or measurement procedures. Compatibility, as far as CDMA2000 systems
are concerned, is to imply that any mobile station is able to place and receive calls in any 800 MHz
IS-95 cellular mobile telecommunication system or in any 1.8 to 2.0 GHz CDMA JSTD-008 system.
Under such compatibility, all CDMA systems (CDMA2000, IS-95 and JSTD-008 systems) are able
to place and receive calls for any CDMA mobile station. To ensure compatibility, both radio system
parameters and call processing procedures should be carefully specified. The sequence of call processing
steps that the MSs and BSs execute to establish connections is specified, along with digital
control messages and, for dual-mode systems, the analog signals that are exchanged between the two
stations. The BS is subject to different compatibility requirements from that of the MS. Radiated
power levels, both desired and undesired, are fully specified for MSs, in order to control the radio
interference that one MS can cause to another.
BSs are fixed in location and their interference is controlled by proper layout and operation of the
system where the station operates. Detailed call processing procedures are specified for MSs to ensure
a uniform response to all BSs. The BS procedures that do not affect the MSs’ operation are left to the
designers of the overall network. This approach to writing the compatibility specification provides
the network designer with sufficient flexibility to respond to local service needs and to account for
particular topography and propagation conditions. CDMA2000 includes provisions for future service
additions and expansion of system capabilities.
Channel naming conventions
To facilitate the understanding of the abbreviations in the illustrations and text given in the discussions
followed, we would like to explain the channel naming convention here. The following naming
conventions apply to all CDMA2000 standards.
A logical channel name consists of three lower case letters followed by “ch” (channel). A hyphen
is used after the first letter. Table 3.6 shows the naming conventions for the logical channels that are
used in this family of standards. For example, the logical channel name for the Forward Dedicated
Traffic Channel is “f-dtch.”
On the other hand, physical channels are named by upper case abbreviations. As in the case of
logical channels, the first letters in the names of the channels indicate the direction of the channel (i.e.,
forward or reverse). Table 3.7 shows the names and meanings of all the physical channels designated
in CDMA2000. For example, the physical channel name for the Forward Fundamental Channel is
“F-FCH.”
Table 3.6 Naming conventions for logical channels in
CDMA2000 standard [354]
First letter Second letter Third letter
f = Forward d = Dedicated t = Traffic
r = Reverse c = Common s = Signaling
Table 3.7 Naming conventions for physical channels in
CDMA2000 standard [354]
Channel name Physical channel
F/R-FCH Forward/Reverse Fundamental Channel
F/R-DCCH Forward/Reverse Dedicated Control Channel
F/R-SCCH Forward/Reverse Supplemental Code Channel
F/R-SCH Forward/Reverse Supplemental Channel
F-PCH Paging Channel
F-QPCH Quick Paging Channel
RACH Access Channel
F/R-CCCH Forward/Reverse Common Control Channel
F/R-PICH Forward/Reverse Pilot Channel
F-APICH Dedicated Auxiliary Pilot Channel
F-TDPICH Transmit Diversity Pilot Channel
F-ATDPICH Auxiliary Transmit Diversity Pilot Channel
F-SYNCH Sync Channel
F-CPCCH Common Power Control Channel
F-CACH Common Assignment Channel
R-EACH Enhanced Access Channel
F-BCCH Broadcast Control Channel
F-PDCH Forward Packet Date Channel
F-PDCCH Forward Packet Data Control Channel
R-ACKCH Reverse Acknowledgment Channel
R-CQICH Reverse Channel Quality Indicator Channel
F-ACKCH Forward Acknowledgment Channel
F-GCH Forward Grant Channel
F-RCCH Forward Rate Control Channel
R-PDCH Reverse Packet Data Channel
R-PDCCH Reverse Packet Data Control Channel
R-REQCH Reverse Request Channel
Layered architecture
The release of the CDMA2000 family of standards that support Spreading Rate 1 operation has been
given in [349] and [355] in the reference list. Figure 3.2 depicts the general system architecture of
CDMA2000, and Figure 3.3 shows the layered architecture in mobile stations.
The development of the CDMA2000 family of standards has, to the greatest extent possible,
adhered to the architecture by specifying different layers in different standards. The physical layer is
specified in [349] and [355], the MAC in [350] and [356], the link access control (LAC) in [351]
and [357], and upper layer signaling architecture in [352] and [358].
CDMA2000 provides full backward compatibility with the cdmaOne system. Backward compatibility
permits the support of cdmaOne mobile stations by the CDMA2000 infrastructure and also
permits the operation of CDMA2000 mobile stations in cdmaOne networks. The CDMA2000 family
also supports the reuse of existing cdmaOne service standards, such as those that define speech services,
data services, Short Message Services (SMSs), and Over-the-Air Provisioning and Activation
services, with the CDMA2000 physical layer.