Though CDMA's application in cellular telephony is relatively new, it is not a new technology. CDMA has been used in many military applications, such as anti-jamming (because of the spread signal, it is difficult to jam or interfere with a CDMA signal), ranging (measuring the distance of the transmission to know when it will be received), and secure communications (the spread spectrum signal is very hard to detect).

CDMA is characterized by high capacity and small cell radius, employing spread-spectrum technology and a special coding scheme.   Capabilities of cdmaOne evolution have already been defined in standards. IS-95B provides ISDN rates up to 64 kbps. The next phase of cdmaOne is a standard knows as 1XRTT and enables 144 kbps packet data in a mobile environment.

Other features available are a two-fold increase in both standby time and voice capacity. All of these capabilities will be available in an existing cdmaOne 1.25 MHz channel. The next phase of cdmaOne evolution will incorporate the capabilities of 1XRTT, support all channel sizes (5 MHz, 10 MHz, etc.), provide circuit and packet data rates up to 2 Mbps, incorporate advanced multimedia capabilities, and include a framework for advanced 3G voice services and vocoders, including voice over packet and circuit data. This phase of the standard will be complete by 4Q99.

 There are now a number of flavours of CDMA:

A unique code is assigned to all speech bits. Signals for all calls are spread across a broad frequency spectrum. The dispersed signals are pulled out of what appears as background noise by a receiver which knows the code for the call it must handle. This technique allows numerous phone calls to be simultaneously transmitted on one radio frequency. As a result, CDMA systems can handle between 10 and 20 times the calling capacity of conventional cellular systems.

• CDMA – An Analogy

It is helpful to use an analogy to explain CDMA technology.
Figure 1-1. A CDMA Analogy

Four speakers are simultaneously giving a presentation, and they each speak a different native language: Spanish, Korean, English, and Chinese. You are in the audience, and English is your native language. You only understand the words of the English speaker and tune out the Spanish, Korean, and Chinese speakers. You hear only what you know and recognize. The same is true for CDMA. Multiple users share the same frequency band at the same time, yet each user only hears his or her own conversation. Each conversation is specially encoded and decoded for each particular user.

• Calls Processed by Digital Codes

When you make a mobile phone call using CDMA technology, the sound of your voice is converted into digital code. This digital signal is first "correlated" with a noise-like code known as Pseudo-Noise (PN) code. The correlator yields an encrypted digital representation of the original signal. This encrypted signal is then modulated, and spread over a very wide frequency spectrum (1.25 MHz). At the receiving terminal, the signal is "demodulated" back to a narrow bandwidth, and then fed into a decorrelator. This decorrelator uses its unique PN code to extract only the information intended for it.

A signal correlated with a given PN code and decorrelated with the same PN code returns the original signal. Decorrelating the signal with the wrong PN code would result in pure noise, containing no discernible information or sound. The randomness of the "mix" of signals contained in the CDMA wideband channel is preserved. Only the correct PN key will extract the correct set of data packets, which when reassembled yield a precise reconstruction of the one original transmission.

CDMA is a "spread spectrum" technology, which means that it spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal.

A CDMA call starts with a standard rate of 9600 bits per second (9.6 kilobits per second). This is then spread to a transmitted rate of about 1.23 Megabits per second. Spreading means that digital codes are applied to the data bits associated with users in a cell. These data bits are transmitted along with the signals of all the other users in that cell. When the signal is received, the codes are removed from the desired signal, separating the users and returning the call to a rate of 9600 bps.

Traditional uses of spread spectrum are in military operations. Because of the wide bandwidth of a spread spectrum signal, it is very difficult to jam, difficult to interfere with, and difficult to identify. This is in contrast to technologies using a narrower bandwidth of frequencies. Since a wideband spread spectrum signal is very hard to detect, it appears as nothing more than a slight rise in the "noise floor" or interference level. With other technologies, the power of the signal is concentrated in a narrower band, which makes it easier to detect.

Increased privacy is inherent in CDMA technology. CDMA phone calls will be secure from the casual eavesdropper since, unlike an analog conversation, a simple radio receiver will not be able to pick individual digital conversations out of the overall RF radiation in a frequency band.

In the final stages of the encoding of the radio link from the base station to the mobile, CDMA adds a special "pseudo-random code" to the signal that repeats itself after a finite amount of time. Base stations in the system distinguish themselves from each other by transmitting different portions of the code at a given time. In other words, the base stations transmit time offset versions of the same pseudo-random code. In order to assure that the time offsets used remain unique from each other, CDMA stations must remain synchronized to a common time reference.

The Global Positioning System (GPS) provides this precise common time reference. GPS is a satellite based, radio navigation system capable of providing a practical and affordable means of determining continuous position, velocity, and time to an unlimited number of users.

CDMA cell coverage is dependent upon the way the system is designed. In fact, three primary system characteristics-Coverage, Quality, and Capacity-must be balanced off of each other to arrive at the desired level of system performance.

In a CDMA system these three characteristics are tightly inter-related. Even higher capacity might be achieved through some degree of degradation in coverage and/or quality. Since these parameters are all intertwined, operators cannot have the best of all worlds: three times wider coverage, 40 times capacity, and "CD" quality sound. For example, the 13 kbps vocoder provides better sound quality, but reduces system capacity as compared to an 8 kbps vocoder.

A handoff is an automatic transfer of a cellular telephone call from:

• one cell to another,
• one cell face to another, or
• one radio to another.

Call quality is maintained as the mobile user moves throughout the coverage area. Handoffs are initiated when the mobile unit measures a neighbor cell's pilot signal (receive) power, and determines that this power level is above an acceptable threshold. The mobile unit or the Executive Cellular Processor Complex (ECPC), depending on handoff type, initiates the handoff processes necessary to maintain the clarity and quality of the phone call.

Handoff Types

CDMA Soft Handoff

A major advantage to call processing in the CDMA system is the concept of soft handoffs. A soft handoff is an intercell handoff, providing uninterrupted speech continuity while the mobile is moving from one cell site to another. The mobile unit's transmit power is continuously monitored and controlled by the base stations involved in the handoff and is kept to a minimum. The net effects of this are increases in the capacity of the system and the coverage of the cells. This monitoring also greatly reduces the battery power used by the mobile, extending battery life.

A soft handoff is essentially a "make before break" connection. The connection between the mobile unit and the cell site is established and may be maintained indefinitely to the two or three cells serving the call. There is no drop off between or among cells. The Protocol Handler for Voice (PHV) board in the 5ESS-2000� AnyMedia™ Platform DCS selects, on a frame by frame basis, the best signal from the participating cells to feed the vocoder. This provides a very high quality voice transmission.

The Lucent Technologies network-centric approach allows soft handoffs between MSCs linked by ATM. This makes it possible to extend soft handoff universes to provide a virtually unlimited network reach.

2-way or 3-way soft handoff

A 2-way or 3-way soft handoff is one in which a mobile unit is communicating with two or three cells at the same time.

Softer Handoff

A softer handoff is an intracell handoff, occurring between sectors of a two sector or three sector "sub-cell." This type of handoff occurs only at the cell site and is independent of the MSC. When a call is in softer handoff, the second connection to the requested call circuit is made before the original connection is broken. The mobile will communicate with only one CDMA Channel Element (CE), which handles and combines the signals from both sectors. Softer handoffs will improve trunking efficiency and provide improved switch performance.

Hard Handoff

A hard handoff (as compared with a soft handoff) is essentially a "break before make" connection. The cell hands off the mobile unit's call to another cell and then drops the call. This is the traditional handoff method for analog and TDMA call processing. Hard handoffs and CDMA-to-analog handoffs are performed by the ECPC.

A CDMA-to-analog handoff can occur between cells within the same system, as well as with cells from different vendors. This type of handoff occurs when the dual mode (both analog and digital capability) CDMA mobile unit is instructed to change its mode from CDMA to analog during a call. Consequently, the assigned Frame Selector is removed from the call configuration. 

CDMA benefits for the Service Provider

• Greater capacity

CDMA provides from 6 to 18 times the capacity of analog cellular, in the same amount of spectrum. Use of a wideband block of Radio Frequency (RF) spectrum for transmission (1.25 MHz) enables CDMA to support up to 60 or more simultaneous conversations on a given carrier in a 3-sector cell site.

• Broader coverage

Multipath signal processing techniques maximize signal intensity, enabling you to extend cell coverage while accommodating more subscribers within the cell area.

• Simplified RF engineering

CDMA's N=1 frequency reuse pattern simplifies frequency engineering when reconfiguring your network. This in turn reduces the time and effort required to expand or modify your system.

• Gives you a competitive edge

CDMA provides the technology platform for advanced revenue-generating features such as personal number services, custom calling services, calling number identification presentation, message waiting indicator, over-the-air service provisioning, and a selection of short message services.

• Investment protection

CDMA integrates easily with your current Series II Systems, protecting your hardware and software investment.

• Strong platform for Personal Communications Services (PCS)

CDMA providers a powerful platform for future investment in PCS technologies. Digital technology and lower power requirements will result in smaller terminals. Messaging service will also improve greatly with PCS, as will in-building mobility through microcells and picocells.

CDMA Benefits for the End User:

• Soft handoff

When traveling through handoff zones, calls exist simultaneously on multiple sectors or cells &150; minimizing dropped calls. Soft and softer hand-off eliminate static and improve voice clarity.

• Integrated voice and data

Service options will include data, integrated voice and data, fax, and tiered services. CDMA's packetized communications structure allows the interweaving of voice and data signals. Variable rate signal coding permits higher-rate voice coding and bandwidth-on-demand for data transmissions.

• Privacy

CDMA is a spread spectrum technology. Spread spectrum is highly secure; would-be eavesdroppers hear only unintelligible broadband noise.

• Longer battery life

Advanced signal processing techniques extend the battery life of the sub-scriber unit, thereby increasing talk time. In addition, sleep mode further increases standby time to nearly seven days while still allowing the unit to receive paging messages.

• Superior Voice Quality

13 Kbps vocoder provides voice quality comparable to landline. Variable rate vocoding transmits speech bits at the minimum rate required to achieve high-quality transmission, maximizing call carrying capacity.

Objective

The objective of this paper is to present the CDMA Development Group’s (CDG) view on key topics with respect to third generation (3G) and address some of the more technical aspects of the cdma2000 3G proposal. The paper also documents the ongoing activities within the CDG and standards bodies that are taking place toward cdmaOne ™ evolution and 3G standards.

 Background

cdmaOne has clearly demonstrated its superiority in the second generation wireless marketplace. In September 1998, only three years after the first commercial deployment, there were 16 million subscribers on cdmaOne systems worldwide. Over 35 countries have either commercial or trial activity ongoing. The CDG has over 100 members of whom 40% are companies based outside of North America, testimony to the truly international reach of CDMA.

The CDG established the Advanced Systems Initiative to provide a growth path for cdmaOne to next generation systems. Primary goals of the initiative include development of a worldwide standard that meets IMT-2000 requirements and other services identified as critical to operator members, and graceful evolution to next generation cdmaOne systems.

The Advanced Systems Initiative is a means for CDG members to define the requirements and priorities for cdmaOne and to collaborate with regional and international standards organizations to meet industry objectives. CDG members have been involved with IMT-2000 since its inception.

In addition to the work of the Advanced Systems Initiative, the CDG leadership is actively engaged in industry-wide efforts on 3G. The CDG is ensuring the rapid evolution of cdmaOne and the development of cdma2000 to meet the needs of operators worldwide, enabling the availability of 3G products and services beginning in 1999.

 Evolution of cdmaOne and Development of cdma2000

The path to 3G

A great deal of attention has been focused on 3G harmonization and convergence. While the CDG believes in the ITU’s vision of a global standard, we are quickly building on the technical foundation of cdmaOne to deliver many advanced services in the near future in a way that allows operators the flexibility to offer these services as the market demands. The CDG efforts are focused around an evolution strategy so that capabilities can be introduced in phases during the next few years, based on and leading to the complete capabilities of cdma2000. The bottom line: The CDG is working aggressively to enable fast-track development of the cdma2000 standard.

cdmaOne is the only technology with a clear evolution to 3G because it builds on the design and framework of today’s cdmaOne system. Looking at 3G from an operator’s perspective, preservation of investments made in infrastructure and spectrum are significant issues in defining requirements for technology migration. Services designated as "3G"will be available with cdmaOne in existing as well as new spectrum bands. This point is important in considering the position of established operators who may not choose, or be able, to get new spectrum.

This point is also vitally important in developing regions considering the allocation of PCS spectrum for 2G. With cdmaOne, operators and subscribers in these regions can reap the benefits of today’s advanced digital technology while assured their investments are protected. Evolution from technologies such as GSM to WCDMA, however, will require significant change out of equipment and costly upgrades.

Capabilities of cdmaOne evolution have already been defined in standards. IS-95B provides ISDN rates up to 64 kbps. The next phase of cdmaOne is a standard knows as 1XRTT and enables 144 kbps packet data in a mobile environment. Other features available when the standard is published in 1Q99 are a two-fold increase in both standby time and voice capacity. All of these capabilities will be available in an existing cdmaOne 1.25 MHz channel.

The next phase of cdmaOne evolution will incorporate the capabilities of 1XRTT, support all channel sizes (5 MHz, 10 MHz, etc.), provide circuit and packet data rates up to 2 Mbps, incorporate advanced multimedia capabilities, and include a framework for advanced 3G voice services and vocoders, including voice over packet and circuit data. This phase of the standard will be complete by 4Q99.

In addition to the capabilities of the cdmaOne air interface, evolution of the ANSI-41 core network will enable subscribers to continue to benefit from advanced services offered by the cdmaOne platform. Investment in costly infrastructure and network upgrades are not necessary.

The myths and the facts about chip rate

The debate about cdma2000 and WCDMA convergence has been based on the fact that these CDMA-based proposals have certain parameter definitions that present an opportunity for compromise. The most discussed and debated parameter is the system chip rate. WCDMA uses a chip rate value of 4.096 Mbps. cdma200 uses 3.6864 Mbps. WCDMA proponents liken the higher rate to more horse power and claim the lower cdma2000 rate degrades performance. This falsity requires clarification.

Deployment scenarios in various bands

First, WCDMA proponents claim that the WCDMA chip rate provides as much as a 10% capacity improvement over that of cdma2000. This should be examined under a realistic scenario of how the technology will be deployed, and must include all factors affecting system performance. While some operators will deploy 3G in as little as 5 MHz of spectrum many will use allocations of 10, 15, or 20 MHz.

This is important since it is the usable spectrum, in conjunction with chip rate, which affects capacity. Figures 1-3 illustrate the deployment scenarios for cdma2000 and WCDMA in 10, 15, and 20 MHz bands respectively. Even with the required guard bands as verified in today’s operational cdmaOne systems, greater overall capacity is achieved with a mixture of cdma2000 1X and 3X channels as compared with using WCDMA channels. With that configuration it can be shown that up to 13% capacity improvement is achievable in a 20 MHz deployment.

.

Figure 1 Deployment scenario for cdma2000 and WCDMA in a 2x 10 MHz operation

Figure 2. Deployment scenario for cdma2000 and WCDMA in a 2x 15 MHz operation

Figure 3. Deployment scenario for cdma2000 and WCDMA in a 2x 20 MHz operation

Examining chip rate in context with other characteristics

Second, chip rate alone does not determine overall system capacity. To build on the automobile analogy referenced earlier, assuming chip rate is the only factor affecting capacity is like assuming tire pressure is the only thing affecting gas mileage. One of the main parameters in determining the capacity of a CDMA system is the ratio of energy per information bit to noise power spectrum density (Eb/No) required to achieve certain QoS (Quality of Service) requirements such as frame or bit error rate. The required Eb/No value depends on frame structure, coding and modulation characteristics, diversity techniques and channel model. The small difference in chip rate between 3.6864 Mcps and 4.096 Mcps has negligible impact on the Eb/No requirement.

Instead, other system designs such as channel structure (including pilot structure), power control mechanisms, diversity techniques, handoff efficiency, and base station synchronization have a much greater impact on system capacity.

The impact of system design on capacity is illustrated in Table 1, where the normalized spectrum efficiency in Erlangs/MHz/cell for voice services in a vehicular environment is shown, taken from the cdma2000 and the UTRA (WCDMA) RTT ( 2 ). Table 1 also contains the simulation results from the RTT evaluation report submitted by the Chinese evaluation group. We can see that a larger chip rate does NOT translate into higher spectrum efficiency.

Table 1. Spectrum efficiency for voice in a vehicular environment: cdma2000 & WCDMA

*Higher Erlangs/MHz/Omni Cell equates to greater efficiency

Consideration of power emissions

Finally, what proponents of the WCDMA chip rate often overlook are the negative effects on spectrum use and power emissions by using the higher value chip rate. The CDMA air interface signal of IMT-2000 needs to fit into a 5 MHz spectrum to comply with different frequency plans around the world. For example, if deployed in a 5 MHz spectrum such as in the D, E, F North American PCS blocks, the WCDMA system as specified currently cannot meet the FCC out-of-band emission requirements. All major wireless technologies use guard bands to separate their signal spectra from those of services in adjacent bands. It is unreasonable to assume that WCDMA can operate without such guard band protection. For instance, the guard band used to separate IS-95 CDMA from TDMA/AMPS is 270 KHz on each side; the guard band used to separate DECT from adjacent service bands is 2.396 MHz to the lower band, and 1.052 MHz to the upper band. This issue is particularly significant for the PDC systems in Japan, as well as anywhere there is another service operating in the band adjacent to the IMT-2000 band.

WCDMA advocates propose using more complex filters to address this. While in theory such an approach can be conceived, the required filter is hard to realize within a 5 MHz bandwidth. Essentially, the purported 10% capacity gain is not realizable in practical deployments that in many markets need to consider adjacent channel interference or FCC power emission requirements – not a realistic solution for operators.

In summary, chip rate is not a simple issue with a direct cause and effect relationship. More is not necessarily better. cdma2000 enables 3G services without the deployment risks and cost of WCDMA.

Convergence and Harmonization

The CDG has been actively trying to achieve the ITU’s goal of a global standard for IMT-2000. To that extent, the CDG and its members have been active on cdma2000/WCDMA harmonization in regional standards bodies (ARIB, ETSI, TIA, TTA, T1P1), discussions with worldwide operators, and meetings with government entities. Convergence can enable a number of benefits for consumers, operators, and manufacturers. ARIB (Japan) recognized this early on and has been instrumental in reducing the number of differences between cdma2000 and WCDMA to a handful. However, some WCDMA proponents have not been receptive to these efforts. The CDG believes in the benefits of convergence, but will not be able to achieve it alone. In any case, cdmaOne evolution proceeds on a fast track, ensuring that operators can deliver 3G services as the market demands.

Conclusion

The growth of cdmaOne technology is certain. Whether new capabilities are labeled 3G or not is not of material importance since the real challenge is having advanced services ready for market when customers demand them, and delivering these services cost effectively. Whatever results from the 3G standards process, cdmaOne operators will have standard solutions that enable 3G services with a clear growth path from today’s systems.

Size:   5.5 x 2.1 x 1.0 inches Weight:   6.4 ounces LCD Size:   1.5 x 2.0 inches   160 x 120 resolution Talk/Standby Time:   Slim battery: 2.5/40 hours   Extended battery: 5/70 hours Network technology: PCS CDMA Frequency Range:   1850 - 1910 MHz transmitter   1930 - 1990 MHz receiver Phone Features The NeoPoint 1000 is the first feature-rich pocket-friendly, affordable smartphone that provides voice clarity, email, ability to access the Internet and personal information management functions in a simple, easy to use handset. It operates on CDMA, a competitor to GSM. The phone features a large, 11-line LCD, which can display as many as ten times the number of characters as today's wireless phones.  This is pretty remarkable when you consider that this big screen comes in a form factor that measures only 5 � inches and weighs 6 pocket-friendly ounces.The list of cool phone features is endless. Advanced Features Internet Minibrowser Email SoftSync™ Plus PC Data SynchronizationWireless Modem / Fax Receive & Transmit Intuitive Text Entry Voice Commands Hotkeys for Multiple Functions Auto Power-Up Screen Save Simple Scroll and Select Large Display, Easy-to-Read Display Applications Features Call History Inbox Schedule Contacts To Do Features PDA Mode for Application-Only Operation Call Timers One-Touch Voice Mail Access Multiple Ringer Settings Any-Key Call Answer Car Auto Answer Key Guard Phone Lock Network Features Caller ID Call Waiting Data Service Conference Calling Call Restriction Call Forwarding Voice Mail

• CDMA is a generic term that describes a wireless air interface based on code division multiple access technology
• cdmaOne™ is a brand name, trademarked and reserved for the exclusive use of CDG member companies, that describes a complete wireless system that incorporates the IS-95 CDMA air interface, the ANSI-41 network standard for switch interconnection and many other standards that make up a complete wireless system.
• cdma2000 is a name identifying the TIA standard for third generation technology that is an evolutionary outgrowth of cdmaOne offering operators who have deployed a second generation cdmaOne system a seamless migration path that economically supports upgrade to 3G features and services within existing spectrum allocations for both cellular and PCS operators. The network interface defined for cdma2000 supports the second generation network aspect of all existing operators regardless of technology (cdmaOne, IS-136 TDMA, or GSM). This standard has been submitted by the TIA to the ITU as part of the IMT-2000 3G process.

  To gracefully migrate cdmaOne to cdma2000 capabilities offering advanced features to the market in a flexible and timely manner, implementation has been broken into evolutionary phases. The first phase capabilities have been defined in a standard known as 1XRTT. Scheduled for publication in the first quarter of 1999, 1XRTT introduces 144 kbps packet data in a mobile environment and speeds beyond this in a fixed environment. Features available with 1XRTT are a two-fold increase in both voice capacity and standby time, more than 300 kbps data capability, advanced packet data services, as well as greatly extended battery life and improved sleep mode technology. All of these capabilities will be available in an existing cdmaOne 1.25 MHz channel.

  cdmaOne evolution to the complete capabilities of cdma2000 will continue in phase two and incorporate the capabilities of 1XRTT, support all channel sizes (5 MHz, 10 MHz, etc.), provide circuit and packet data rates up to 2 Mbps, incorporate advanced multimedia capabilities, and include a framework for advanced 3G voice services and vocoders, including voice over packet and circuit data.

• W-CDMA is a name identifying the ETSI and NTT DoCoMo standards for third generation technology submitted to the ITU as part of the IMT-2000 3G process. This standard encompasses an air interface that uses the CDMA technique but it is not compatible as defined for both air and network interfaces with cdmaOne, cdma2000 or IS-136. The air interface specification is not compatible with GSM and therefore does not support evolutionary migration.

  Chart 1: Main differences between cdma2000 and W-CDMA

  	cdma2000	W-CDMA
  Base station synchronization	synchronous	asynchronous
  Base station acquisition and detection	Time-shifted PN correlation	3 step parallel code search for base station detection and slot/frame synchronization
  Frame length	20 ms	10 ms
  Chip rate	3.6864 Mcps	4.096 Mcps*
  Forward link pilot for channel estimation Antenna beam forming and spot beams	CDM common pilot CDM dedicated auxillary pilot	TDM dedicated pilot TDM dedicated pilot

*a revised chip rate of 3.84 has been proposed for W-CDMA which remains incompatible with existing cdmaOne systems.

Forced hand-offs are one problem with CDMA within a hierarchical cell structure, another problem is power control. Consider two mobiles physically close to each other; one connected to a microcell base station and another outside the microcell and transmitting towards the base station of the umbrella cell. The first mobile will be transmitting on reasonably low power but the second must use high power to reach the distant umbrella cell base station. By doing so he will interfere with the transmission of the mobile in the microcell - which will then have to increase its power.

This is the near-far effect - and it obliterates the usual power-saving features of microcells.

The solution is to use different frequencies for microcells and umbrella cells - as in TDMA - and there are proposed methods for doing this in CDMA. But this does not help IS-95 CDMA as that standard does not support mobile-assisted hand-offs between different carrier frequencies.

There is therefore a fundamental inconsistency within the IS-95 standard. The soft hand-over algorithm requires umbrella cells and microcells to be on the same carrier frequency. But power control is also important for gaining high capacity and the near-far effect means power control can only be preserved by having umbrella cells and microcells on different frequencies.

Forced hand-off within hierarchical cell structures is a serious problem for CDMA. But there are other hand-off problems as well. In particular, there is no soft hand-off between switch borders and so the transition from CDMA to analogue is through a hard hand-off. And you can't get back. At present, IS-95 does not support analogue to digital hand-off

Soft hand-off is also an attractive feature within CDMA. But it too has its disadvantages as it implies the system cannot control where the subscriber is; in time this could be corrected but probably only at the expense of recalling terminals for software upgrades. And like most attractive features, it comes with an associated overhead. With soft hand-off each caller uses two base stations 50 per cent of the time - the cost per voice call and the switching complexity are therefore increased.