CDMA

Code division multiple access Steps in CDMA Modulation 1 In CDMA a locally generated code runs at a much higher rate than the data to be transmitted

Code division multiple access Steps in CDMA Modulation 1 Choosing the codes used to modulate the signal is very important in the performance of CDMA systems

Code division multiple access Steps in CDMA Modulation 1 Similarly, in radio CDMA, each group of users is given a shared code

Code division multiple access Steps in CDMA Modulation 1 In general, CDMA belongs to two basic categories: synchronous (orthogonal codes) and asynchronous (pseudorandom codes).

Code division multiple access Code division multiplexing (Synchronous CDMA) 1 Some properties of the dot product aid understanding of how W-CDMA works

Code division multiple access Code division multiplexing (Synchronous CDMA) 1 Each user in synchronous CDMA uses a code orthogonal to the others' codes to modulate their signal

Code division multiple access Asynchronous CDMA 1 In other words, unlike synchronous CDMA, the signals of other users will appear as noise to the signal of interest and interfere slightly with the desired signal in proportion to number of users.

Code division multiple access Asynchronous CDMA 1 All forms of CDMA use spread spectrum process gain to allow receivers to partially discriminate against unwanted signals. Signals encoded with the specified PN sequence (code) are received, while signals with different codes (or the same code but a different timing offset) appear as wideband noise reduced by the process gain.

Code division multiple access Asynchronous CDMA 1 In CDMA cellular, the base station uses a fast closed-loop power control scheme to tightly control each mobile's transmit power.

Code division multiple access Spread-spectrum characteristics of CDMA 1 CDMA is also resistant to jamming

Code division multiple access Spread-spectrum characteristics of CDMA 1 CDMA signals are also resistant to multipath fading

Code division multiple access Spread-spectrum characteristics of CDMA 1 Another reason CDMA is resistant to multipath interference is because the delayed versions of the transmitted pseudo-random codes will have poor correlation with the original pseudo- random code, and will thus appear as another user, which is ignored at the receiver

Code division multiple access Spread-spectrum characteristics of CDMA 1 Some CDMA devices use a rake receiver, which exploits multipath delay components to improve the performance of the system. A rake receiver combines the information from several correlators, each one tuned to a different path delay, producing a stronger version of the signal than a simple receiver with a single correlation tuned to the path delay of the strongest signal.

Code division multiple access Spread-spectrum characteristics of CDMA 1 Reusing the same frequency in every cell eliminates the need for frequency planning in a CDMA system; however, planning of the different pseudo-random sequences must be done to ensure that the received signal from one cell does not correlate with the signal from a nearby cell.

Code division multiple access Spread-spectrum characteristics of CDMA 1 In contrast, CDMA systems use the soft hand off, which is undetectable and provides a more reliable and higher quality signal.

Code division multiple access Collaborative CDMA 1 In this approach, instead of using one sequence per user as in conventional CDMA, the authors group a small number of users to share the same spreading sequence and enable group spreading and despreading operations

TD-SCDMA 1 Time Division Synchronous Code Division Multiple Access (TD-SCDMA) or UTRA/UMTS-TDD 1.28 Mcps Low Chip Rate (LCR), is an air interface found in UMTS mobile telecommunications networks in China as an alternative to W- CDMA. Together with TD-CDMA, it is also known as UMTS-TDD or IMT 2000 Time- Division (IMT-TD).

TD-SCDMA 1 The term "TD-SCDMA" is misleading. While it suggests covering only a channel access method based on CDMA, it is actually the common name for the whole air interface specification.

TD-SCDMA 1 TD-SCDMA uses the S-CDMA channel access method across multiple time slots.

TD-SCDMA - Objectives 1 TD-SCDMA was developed in the People's Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang Telecom, and Siemens AG in an attempt to avoid dependence on Western technology. This is likely primarily for practical reasons, since other 3G formats require the payment of patent fees to a large number of Western patent holders.

TD-SCDMA - Objectives 1 TD-SCDMA proponents also claim it is better suited for densely populated areas. Further, it is supposed to cover all usage scenarios, whereas W-CDMA is optimised for symmetric traffic and macro cells, while TD-CDMA is best used in low mobility scenarios within micro or pico cells.

TD-SCDMA - Objectives 1 TD-SCDMA is based on spread spectrum technology which makes it unlikely that it will be able to completely escape the payment of license fees to western patent holders. The launch of a national TD- SCDMA network was initially projected by 2005 but only reached large scale commercial trials with 60,000 users across eight cities in

TD-SCDMA - Objectives 1 On January 7, 2009, China granted a TD-SCDMA 3G licence to China Mobile.

TD-SCDMA - Objectives 1 On September 21, 2009, China Mobile officially announced that it had 1,327,000 TD-SCDMA subscribers as of the end of August,

TD-SCDMA - Objectives 1 While TD is primarily a China-only system, it may well be exported to developing countries. It is likely to be replaced with a newer TD-LTE system over the next 5 years.

TD-SCDMA - Deployment and usage 1 On January 20, 2006, Ministry of Information Industry of the People's Republic of China formally announced that TD-SCDMA is the country's standard of 3G mobile telecommunication

TD-SCDMA - Deployment and usage 1 The standard has been adopted by 3GPP since Rel- 4, known as "UTRA TDD 1.28Mbps Option".

TD-SCDMA - Deployment and usage 1 On March 28, 2008, China Mobile Group announced TD-SCDMA "commercial trials" for 60,000 test users in eight cities from April 1, Networks using other 3G standards (WCDMA and CDMA2000 EV/DO) had still not been launched in China, as these were delayed until TD- SCDMA was ready for commercial launch.

TD-SCDMA - Deployment and usage 1 Licences for two existing 3G standards, W-CDMA and CDMA2000 1xEV-DO, were assigned to China Unicom and China Telecom, respectively

TD-SCDMA - Technical highlights 1 TD-SCDMA uses TDD, in contrast to the FDD scheme used by W-CDMA

TD-SCDMA - Technical highlights 1 TD-SCDMA also uses TDMA in addition to the CDMA used in WCDMA. This reduces the number of users in each timeslot, which reduces the implementation complexity of multiuser detection and beamforming schemes, but the non- continuous transmission also reduces coverage (because of the higher peak power needed), mobility (because of lower power control frequency) and complicates radio resource management algorithms.

TD-SCDMA - Technical highlights 1 The "S" in TD-SCDMA stands for "synchronous", which means that uplink signals are synchronized at the base station receiver, achieved by continuous timing adjustments. This reduces the interference between users of the same timeslot using different codes by improving the orthogonality between the codes, therefore increasing system capacity, at the cost of some hardware complexity in achieving uplink synchronization.

TD-SCDMA - Documentation 1 TS Multiplexing and channel coding (TDD)

TD-SCDMA - Documentation 1 TS Spreading and modulation (TDD)

TD-SCDMA - Documentation 1 TS Physical layer procedures (TDD)

CDMA CDMA2000 (also known as C2K or IMT Multi ‑ Carrier (IMT ‑ MC)) is a family of 3G mobile technology standards, which use CDMA channel access, to send voice, data, and signaling data between mobile phones and cell sites. The name CDMA2000 actually denotes a family of standards that represent the successive, evolutionary stages of the underlying technology. These are, in order of evolution:

CDMA CDMA2000 1xEV-DO Revision C or Ultra Mobile Broadband (UMB)

CDMA All are approved radio interfaces for the ITU's IMT CDMA2000 has a relatively long technical history and is backward-compatible with its previous 2G iteration IS-95 (cdmaOne). In the United States, CDMA2000 is a registered trademark of the Telecommunications Industry Association (TIA-USA).

CDMA X 1 CDMA2000 1X (IS-2000), also known as 1x and 1xRTT, is the core CDMA2000 wireless air interface standard

CDMA xEV-DO 1 Evolution-Data Only

CDMA xEV-DO 1 It is standardized by 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and has been adopted by many mobile phone service providers around the world – particularly those previously employing CDMA networks

CDMA X Advanced 1 1X Advanced is the evolution of CDMA2000 1X. It provides up to four times the capacity and 70% more coverage compared to 1X.

CDMA Networks 1 The CDMA Development Group states that, as of May 2012, there are 329 operators in 121 countries offering CDMA2000 1X and/or 1xEV-DO service.

CDMA History 1 The intended 4G successor to CDMA2000 was UMB (Ultra Mobile Broadband); however, in November 2008, Qualcomm announced it was ending development of the technology, favoring LTE instead.

Sprint Corporation - CDMA/1xRTT/EVDO 1 Sprint operates a nationwide CDMA network in the 1900 MHz PCS band. In 2006, Sprint's EV-DO "Power Vision" network reached more than 190 million people. Sprint has then continued upgrading their 3G EV-DO network until it reaches 260 million people in

Chip (CDMA) 1 In digital communications, a chip is a pulse of a direct-sequence spread spectrum (DSSS) code, such as a pseudo-noise code sequence used in direct-sequence code division multiple access (CDMA) channel access techniques.

Chip (CDMA) 1 In a binary direct-sequence system, each chip is typically a rectangular pulse of +1 or –1 amplitude, which is multiplied by a data sequence (similarly +1 or –1 representing the message bits) and by a carrier waveform to make the transmitted signal. The chips are therefore just the bit sequence out of the code generator; they are called chips to avoid confusing them with message bits.

Chip (CDMA) 1 The chip rate of a code is the number of pulses per second (chips per second) at which the code is transmitted (or received). The chip rate is larger than the symbol rate, meaning that one symbol is represented by multiple chips. The ratio is known as the spreading factor (SF) or processing gain:

Chip (CDMA) - Orthogonal variable spreading factor 1 Orthogonal variable spreading factor (OVSF) is an implementation of Code division multiple access (CDMA) where before each signal is transmitted, the signal is spread over a wide spectrum range through the use of a user's code. Users' codes are carefully chosen to be mutually orthogonal to each other.

Chip (CDMA) - Orthogonal variable spreading factor 1 These codes are derived from an OVSF code tree, and each user is given a different, unique code. An OVSF code tree is a complete binary tree that reflects the construction of Hadamard matrices.

GLONASS - CDMA signals 1 Since 2008, new CDMA signals are being researched for use with GLONASS.

GLONASS - CDMA signals 1 According to preliminary statements from GLONASS developers, there will be three open and two restricted CDMA signals. The open signal L3OC is centered at MHz and uses BPSK(10) modulation for both data and pilot channels; the ranging code transmits at million chips per second, modulated onto the carrier frequency using QPSK with in-phase data and quadrature pilot. The data is error-coded with 5-bit Barker code and the pilot with 10-bit Neuman- Hoffman code.

GLONASS - CDMA signals 1 Open L1OC and restricted L1SC signals are centered at MHz, and open L2OC and restricted L2SC signals are centered at MHz, overlapping with GLONASS FDMA signals

GLONASS - CDMA signals 1 Binary phase-shift keying (BPSK) is used by standard GPS and GLONASS signals, however both BPSK and quadrature phase-shift keying (QPSK) can be considered as variations of quadrature amplitude modulation (QAM), specifically QAM-2 and QAM-4. Binary offset carrier (BOC) is the modulation used by Galileo, modernized GPS, and COMPASS.

GLONASS - CDMA signals 1 The navigational message of the L3OC signal is transmitted at 100 bit/s

GLONASS - CDMA signals 1 Satellite seriesLaunchCurrent status Clock errorFDMA signalsCDMA signals Interoperability CDMA signals

GLONASS - CDMA signals 1 GLONASS Out of service5×10−13L1OF, L1SFL2SF

GLONASS - CDMA signals 1 "O": open signal (standard precision), "S": obfuscated signal (high precision); "F":FDMA, "С":CDMA; n=−7,−6,−5,...,6

GLONASS - CDMA signals 1 ‡Glonass-M series will include L3OC signal from

GLONASS - CDMA signals 1 Glonass-K1 test satellite launched in 2011 introduced L3OC signal. The final Glonass-M satellites launched in will also include L3OC signal.

GLONASS - CDMA signals 1 Glonass-K2 satellites, to be launched in 2015, will feature a full suite of modernized CDMA signals in the existing L1 and L2 bands, which includes L1SC, L1OC, L2SC, and L2OC, as well as the L3OC signal. Glonass-K2 should gradually replace existing satellites starting from 2017, when Glonass-M launches will cease.

GLONASS - CDMA signals 1 Glonass-KM satellites will be launched by Additional open signals are being studied for these satellites, based on the same frequencies and formats as GPS signals L5 and L1C and corresponding Galileo/COMPASS signals E1, E5a and E5b. These signals include:

GLONASS - CDMA signals 1 The open signal L1OCM will use BOC(1,1) modulation centered at MHz, similar to modernized GPS signal L1C and Galileo/COMPASS signal E1;

GLONASS - CDMA signals 1 The open signal L5OCM will use BPSK(10) modulation centered at MHz, similar to the GPS "Safety of Life" (L5) and Galileo/COMPASS signal E5a;

GLONASS - CDMA signals 1 The open signal L3OCM will use BPSK(10) modulation centered at MHz, similar to Galileo/COMPASS signal E5b.

GLONASS - CDMA signals 1 Such an arrangement will allow easier and cheaper implementation of multi-standard GNSS receivers.

GLONASS - CDMA signals 1 With the introduction of CDMA signals, the constellation will be expanded to 30 active satellites by 2025; this may require eventual deprecation of FDMA signals

TD-CDMA 1 TD-CDMA, an acronym for "Time-division - CDMA," is a channel access method based on using spread spectrum across multiple time slots.

TD-CDMA - Standardized implementations 1 TD-CDMA is used in IMT-2000's 3G air interface, defined as IMT-TD Time- Division, and can also be found in use in UMTS air interfaces, as standardized by the 3GPP in UTRA-TDD HCR. UTRA-TDD HCR is closely related to W-CDMA (UMTS), and provides the same types of channels where possible. UMTS's HSDPA/HSUPA enhancements are also implemented under TD-CDMA.

CDMA 1 'Code division multiple access' ('CDMA') is a channel access method used by various radio communication technologies.

CDMA 1 CDMA is an example of multiple access, which is where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth (signal processing)|bandwidth). To permit this to be achieved without undue interference between the users CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code).

CDMA 1 CDMA is used as the access method in many List of mobile phone standards|mobile phone standards such as IS-95|cdmaOne, CDMA2000 (the 3G evolution of cdmaOne), and WCDMA (the 3G standard used by GSM carriers), which are often referred to as simply CDMA.

Samsung Telecommunications - CDMA era (1996–1998) 1 For the CDMA cellular market, it emphasized the phone's new functions, for example, its voice recognition feature

Samsung Telecommunications - CDMA era (1996–1998) 1 By the end of 1997, one year after the CDMA service was first launched; Samsung had achieved a 57% market share in the CDMA cellular market and 58% in the Personal Communications Service|PCS market. Also, in April 1997, it achieved sales of one million CDMA phone units.

Mobile broadband - CDMA family 1 Established in late 1998, the global 3GPP2|Third Generation Partnership Project 2 (3GPP2) develops the evolving CDMA family of standards, which includes cdmaOne, CDMA2000, and CDMA2000 EV- DO.[ c/AboutHome.cfm About 3GPP2], 3GPP2 website, retrieved 27 February

CDMA - History 1 The technology of CDMA was used in 1957, when the young military radio engineer Leonid Kupriyanovich in Moscow, made an experimental model of a wearable automatic mobile phone, called LK-1 by him, with a base station

CDMA - Uses 1 * One of the early applications for code division multiplexing is in Global Positioning System|GPS. This predates and is distinct from its use in mobile phones.

CDMA - Uses 1 * The Qualcomm standard IS-95, marketed as cdmaOne.

CDMA - Uses 1 * The Qualcomm standard IS-2000, known as CDMA2000. This standard is used by several mobile phone companies, including the Globalstar satellite phone network.

CDMA - Uses 1 * The UMTS 3G mobile phone standard, which uses W-CDMA.

CDMA - Uses 1 * CDMA has been used in the 'OmniTRACS' satellite system for transportation logistics.

CDMA - Steps in CDMA Modulation 1 In CDMA a locally generated code runs at a much higher rate than the data to be transmitted

CDMA - Steps in CDMA Modulation 1 Choosing the codes used to modulate the signal is very important in the performance of CDMA systems

CDMA - Steps in CDMA Modulation 1 Similarly, in radio CDMA, each group of users is given a shared code

CDMA - Code division multiplexing (Synchronous CDMA) 1 Some properties of the dot product aid understanding of how W-CDMA works

CDMA - Code division multiplexing (Synchronous CDMA) 1 Each user in synchronous CDMA uses a code orthogonal to the others' codes to modulate their signal

CDMA - Example 1 These vectors will be assigned to individual users and are called the code, chip (CDMA)|chip code, or chipping code

CDMA - Example 1 Each user is associated with a different code, say 'v'. A 1 bit is represented by transmitting a positive code, 'v', and a 0 bit is represented by a negative code, –'v'. For example, if 'v' = (v0, v1) = (1, –1) and the data that the user wishes to transmit is (1, 0, 1, 1), then the transmitted symbols would be ('v', –'v', 'v', 'v') = (v0, v1, –v0, – v1, v0, v1, v0, v1) = (1, –1, –1, 1, 1, –1, 1, –1). For the purposes of this article, we call this constructed vector the transmitted vector.

CDMA - Example 1 Each sender has a different, unique vector 'v' chosen from that set, but the construction method of the transmitted vector is identical.

CDMA - Example 1 Now, due to physical properties of interference, if two signals at a point are in phase, they add to give twice the amplitude of each signal, but if they are out of phase, they subtract and give a signal that is the difference of the amplitudes. Digitally, this behaviour can be modelled by the addition of the transmission vectors, component by component.

CDMA - Example 1 If sender0 has code (1, –1) and data (1, 0, 1, 1), and sender1 has code (1, 1) and data (0, 0, 1, 1), and both senders transmit simultaneously, then this table describes the coding steps:

CDMA - Example 1 Because signal0 and signal1 are transmitted at the same time into the air, they add to produce the raw signal:

CDMA - Example 1 Further, after decoding, all values greater than 0 are interpreted as 1 while all values less than zero are interpreted as 0. For example, after decoding, data0 is (2, –2, 2, 2), but the receiver interprets this as (1, 0, 1, 1). Values of exactly 0 means that the sender did not transmit any data, as in the following example:

CDMA - Example 1 Assume signal0 = (1, –1, –1, 1, 1, –1, 1, – 1) is transmitted alone. The following table shows the decode at the receiver:

CDMA - Example 1 When the receiver attempts to decode the signal using sender1's code, the data is all zeros, therefore the cross correlation is equal to zero and it is clear that sender1 did not transmit any data.

CDMA - Asynchronous CDMA 1 In other words, unlike synchronous CDMA, the signals of other users will appear as noise to the signal of interest and interfere slightly with the desired signal in proportion to number of users.

CDMA - Efficient practical utilization of fixed frequency spectrum 1 In theory, CDMA, TDMA and FDMA have exactly the same spectral efficiency but practically, each has its own challenges – power control in the case of CDMA, timing in the case of TDMA, and frequency generation/filtering in the case of FDMA.

CDMA - Efficient practical utilization of fixed frequency spectrum 1 TDMA systems must carefully synchronize the transmission times of all the users to ensure that they are received in the correct time slot and do not cause interference

CDMA - Flexible allocation of resources 1 In a bursty traffic environment like mobile telephony, the advantage afforded by asynchronous CDMA is that the performance (bit error rate) is allowed to fluctuate randomly, with an average value determined by the number of users times the percentage of utilization

CDMA - Flexible allocation of resources 1 By comparison, asynchronous CDMA transmitters simply send when they have something to say, and go off the air when they don't, keeping the same PN signature sequence as long as they are connected to the system.

CDMA - Spread-spectrum characteristics of CDMA 1 CDMA is also resistant to jamming

CDMA - Spread-spectrum characteristics of CDMA 1 CDMA signals are also resistant to multipath fading

CDMA - Spread-spectrum characteristics of CDMA 1 Another reason CDMA is resistant to multipath interference is because the delayed versions of the transmitted pseudo-random codes will have poor correlation with the original pseudo- random code, and will thus appear as another user, which is ignored at the receiver

CDMA - Spread-spectrum characteristics of CDMA 1 Reusing the same frequency in every cell eliminates the need for frequency planning in a CDMA system; however, planning of the different pseudo-random sequences must be done to ensure that the received signal from one cell does not correlate with the signal from a nearby cell.

CDMA - Spread-spectrum characteristics of CDMA 1 In contrast, CDMA systems use the soft hand off, which is undetectable and provides a more reliable and higher quality signal.

Samsung Galaxy Note II - TD-SCDMA phone 1 GT-N7108 is to support TD-SCDMA networks in the 1.9GHz and 2.0GHz bands, and connect to the GSM/GPRS/EDGE 1.9GHz band.

Universal Mobile Telecommunications System - W-CDMA (UTRA-FDD) 1 'W-CDMA' uses the DS-CDMA channel access method with a pair of 5MHz wide channels. In contrast, the competing CDMA2000 system uses one or more available 1.25MHz channels for each direction of communication. W-CDMA systems are widely criticized for their large spectrum usage, which has delayed deployment in countries that acted relatively slowly in allocating new frequencies specifically for 3G services (such as the United States).

Universal Mobile Telecommunications System - W-CDMA (UTRA-FDD) 1 The specific Band (radio)|frequency bands originally defined by the UMTS standard are 1885–2025MHz for the mobile-to-base (uplink) and 2110–2200MHz for the base- to-mobile (downlink)

Universal Mobile Telecommunications System - TD-CDMA (UTRA-TDD 3.84 Mcps High Chip Rate) 1 Unlike W-CDMA, it does not need separate frequency bands for up- and downstream, allowing deployment in tight frequency bands.

Universal Mobile Telecommunications System - TD-SCDMA (UTRA-TDD 1.28 Mcps low chip rate) 1 Unlike the other air interfaces, TD-SCDMA was not part of UMTS from the beginning but has been added in Release 4 of the specification.

CdmaOne 1 'Interim Standard 95 (IS-95)' is the first CDMA-based digital cellular standard by Qualcomm. The brand name for IS-95 is 'cdmaOne'. IS-95 is also known as TIA- EIA-95.

CdmaOne 1 It is a 2G mobile telecommunications standard that uses CDMA, a multiple access scheme for digital radio, to send voice, data and signaling data (such as a dialed telephone number) between mobile telephones and cellular phone|cell sites.

CdmaOne 1 Since larger numbers of phones can be served by smaller numbers of cell-sites, CDMA-based standards have a significant economic advantage over TDMA-based standards, or the oldest cellular standards that used FDMA|frequency-division multiplexing.

CdmaOne 1 In North America, the technology competed with Digital AMPS (IS-136, a Time division multiple access|TDMA technology). It is now being supplanted by IS-2000 (CDMA2000), a later CDMA- based standard.

CdmaOne - Protocol revisions 1 cdmaOne's technical history is reflective of both its birth as a Qualcomm internal project, and the world of then-unproven competing digital cellular standards under which it was developed. The 'term IS-95' generically applies to the earlier set of protocol revisions, namely P_REV's one through five.

CdmaOne - Protocol revisions 1 P_REV=1 was developed under an American National Standards Institute|ANSI standards process with documentation reference J-STD-008

CdmaOne - Protocol revisions 1 P_REV=3 is termed Technical Services Bulletin 74 (TSB-74). TSB-74 was the next incremental improvement over IS-95A in the TIA standards process.

CdmaOne - Protocol revisions 1 P_REV=4 is termed Interim Standard 95B (IS-95B) Phase I, and P_REV=5 is termed Interim Standard 95B (IS-95B) Phase II. The IS-95B standards track provided for a merging of the TIA and ANSI standards tracks under the TIA, and was the first document that provided for interoperation of IS-95 mobile handsets in both band classes (dual-band operation). P_REV=4 was by far the most popular variant of IS- 95, with P_REV=5 only seeing minimal uptake in South Korea.

CdmaOne - Protocol revisions 1 P_REV=6 and beyond fall under the CDMA2000 umbrella. Besides technical improvements, the IS-2000 documents are much more mature in terms of layout and content. They also provide backwards- compatibility to IS-95.

CdmaOne - Protocol details 1 The IS-95 standards describe an air interface, a set of protocols used between mobile units and the network. IS-95 is widely described as a three-layer stack, where L1 corresponds to the physical (PHY) layer, L2 refers to the Media Access Control (MAC) and Link-Access Control (LAC) sublayers, and L3 to the call- processing state machine.

CdmaOne - Physical layer 1 In the forward direction, radio signals are transmitted by base stations (BTS's). Every BTS is synchronized with a GPS receiver so transmissions are tightly controlled in time. All forward transmissions are QPSK with a chip rate of 1,228,800 per second. Each signal is spread with a Walsh code of length 64 and a pseudo-random noise code (PN Sequences|PN code) of length ^, yielding a PN roll-over period of \frac ms.

CdmaOne - Physical layer 1 For the reverse direction, radio signals are transmitted by the mobile. Reverse link transmissions are OQPSK in order to operate in the optimal range of the mobile's power amplifier. Like the forward link, the chip rate is 1,228,800 per second and signals are spread with Walsh codes and the pseudo-random noise code, which is also known as a Short Code.

CdmaOne - Forward broadcast channels 1 Every BTS dedicates a significant amount of output power to a pilot channel, which is an unmodulated PN sequence (in other words, spread with Walsh code 0). Each BTS sector in the network is assigned a PN offset in steps of 64 chips. There is no data carried on the forward pilot. With its strong autocorrelation function, the forward pilot allows mobiles to determine system timing and distinguish different BTS's for handoff.

CdmaOne - Forward broadcast channels 1 When a mobile is searching, it is attempting to find pilot signals on the network by tuning to particular radio frequencies, and performing a cross- correlation across all possible PN phases. A strong correlation peak result indicates the proximity of a BTS.

CdmaOne - Forward broadcast channels 1 Other forward channels, selected by their Walsh code, carry data from the network to the mobiles. Data consists of network signaling and user traffic. Generally, data to be transmitted is divided into frames of bits. A frame of bits is passed through a convolutional encoder, adding forward error correction redundancy, generating a frame of symbols. These symbols are then spread with the Walsh and PN sequences and transmitted.

CdmaOne - Forward broadcast channels 1 BTSs transmit a sync channel spread with Walsh code 32. The sync channel frame is \frac ms long, and its frame boundary is aligned to the pilot. The sync channel continually transmits a single message, the Sync Channel Message, which has a length and content dependent on the P_REV. The message is transmitted 32 bits per frame, encoded to 128 symbols, yielding a rate of 1200 bit/s. The Sync Channel Message contains information about the network, including the PN offset used by the BTS sector.

CdmaOne - Forward broadcast channels 1 Once a mobile has found a strong pilot channel, it listens to the sync channel and decodes a Sync Channel Message to develop a highly accurate synchronization to system time. At this point the mobile knows whether it is roaming, and that it is in service.

CdmaOne - Forward broadcast channels 1 BTSs transmit at least one, and as many as seven, paging channels starting with Walsh code 1. The paging channel frame time is 20 ms, and is time aligned to the IS-95 system (i.e. GPS) 2-second roll- over. There are two possible rates used on the paging channel: 4800 bit/s or 9600 bit/s. Both rates are encoded to symbols per second.

CdmaOne - Forward broadcast channels 1 The paging channel contains signaling messages transmitted from the network to all idle mobiles. A set of messages communicate detailed network overhead to the mobiles, circulating this information while the paging channel is free. The paging channel also carries higher-priority messages dedicated to setting up calls to and from the mobiles.

CdmaOne - Forward traffic channels 1 The Walsh space not dedicated to broadcast channels on the BTS sector is available for traffic channels. These channels carry the individual voice and data calls supported by IS-95. Like the paging channel, traffic channels have a frame time of 20ms.

CdmaOne - Forward traffic channels 1 Since voice and user data are intermittent, the traffic channels support variable-rate operation. Every 20 ms frame may be transmitted at a different rate, as determined by the service in use (voice or data). P_REV=1 and P_REV=2 supported rate set 1, providing a rate of 1200, 2400, 4800, or 9600 bit/s. P_REV=3 and beyond also provided rate set 2, yielding rates of 1800, 3600, 7200, or bit/s.

CdmaOne - Forward traffic channels 1 For voice calls, the traffic channel carries frames of vocoder data. A number of different vocoders are defined under IS- 95, the earlier of which were limited to rate set 1, and were responsible for some user complaints of poor voice quality. More sophisticated vocoders, taking advantage of modern DSPs and rate set 2, remedied the voice quality situation and are still in wide use in

CdmaOne - Forward traffic channels 1 The mobile receiving a variable-rate traffic frame does not know the rate at which the frame was transmitted. Typically, the frame is decoded at each possible rate, and using the quality metrics of the Viterbi decoder, the correct result is chosen.

CdmaOne - Forward traffic channels 1 Traffic channels may also carry circuit- switch data calls in IS-95. The variable- rate traffic frames are generated using the IS-95 Radio Link Protocol (RLP). RLP provides a mechanism to improve the performance of the wireless link for data. Where voice calls might tolerate the dropping of occasional 20 ms frames, a data call would have unacceptable performance without RLP.

CdmaOne - Forward traffic channels 1 Under IS-95B P_REV=5, it was possible for a user to use up to seven supplemental code (traffic) channels simultaneously to increase the throughput of a data call. Very few mobiles or networks ever provided this feature, which could in theory offer bit/s to a user.

CdmaOne - Forward traffic channels 1 After convolution coding and repetition, symbols are sent to a 20 ms block interleaver, which is a 24 by 16 array.

CdmaOne - Capacity 1 IS-95 and its use of CDMA techniques, like any other communications system, have their throughput limited according to Shannon's theorem. Accordingly, capacity improves with SNR and bandwidth. IS-95 has a fixed bandwidth, but fares well in the digital world because it takes active steps to improve SNR.

CdmaOne - Capacity 1 With CDMA, signals that are not correlated with the channel of interest (such as other PN offsets from adjacent cellular base stations) appear as noise, and signals carried on other Walsh codes (that are properly time aligned) are essentially removed in the de-spreading process

CdmaOne - Capacity 1 Active (slow) power control is also used on the forward traffic channels, where during a call, the mobile sends signaling messages to the network indicating the quality of the signal. The network will control the transmitted power of the traffic channel to keep the signal quality just good enough, thereby keeping the noise level seen by all other users to a minimum.

CdmaOne - Capacity 1 The receiver also uses the techniques of the rake receiver to improve SNR as well as perform soft handoff.

CdmaOne - Layer 2 1 Once a call is established, a mobile is restricted to using the traffic channel. A frame format is defined in the MAC for the traffic channel that allows the regular voice (vocoder) or data (RLP) bits to be multiplexed with signaling message fragments. The signaling message fragments are pieced together in the LAC, where complete signaling messages are passed on to Layer 3.

OFDMA - Claimed advantages over CDMA 1 * OFDM can combat multipath interference with more robustness and less complexity.

OFDMA - Claimed advantages over CDMA 1 * OFDMA can achieve a higher MIMO spectral efficiency due to providing flatter frequency channels than a CDMA rake receiver can.

OFDMA - Claimed advantages over CDMA 1 * No cell size breathing as more users connect.

Global navigation satellite systems - CDMA signals 1 L1CR and L5R CDMA interoperable with GPS and Galileo[ 0/ICG5/18october/03.pdf GLONASS Status and Development], G.Stupak, 5th ICG Meeting[ 487 Russia’s First GLONASS-K In Orbit, CDMA Signals Coming]

Global navigation satellite systems - CDMA signals 1 According to preliminary statements from GLONASS developers, there will be three open and two restricted CDMA signals. The open signal L3OC is centered at MHz and uses BPSK(10) modulation for both data and pilot channels; the ranging code transmits at million Chip (CDMA)|chips per second, modulated onto the carrier frequency using QPSK with in-phase data and quadrature pilot. The data is error-coded with 5-bit Barker code and the pilot with 10-bit Neuman-Hoffman code.

Global navigation satellite systems - CDMA signals 1 Open L1OC and restricted L1SC signals are centered at MHz, and open L2OC and restricted L2SC signals are centered at MHz, overlapping with GLONASS FDMA signals

Global navigation satellite systems - CDMA signals 1 The navigational message of the L3OC signal is transmitted at 100 bit/s

Global navigation satellite systems - CDMA signals 1 * The open signal L1OCM will use BOC(1,1) modulation centered at MHz, similar to GPS signals#L1C|modernized GPS signal L1C and Galileo/COMPASS signal E1;

Global navigation satellite systems - CDMA signals 1 * The open signal L5OCM will use BPSK(10) modulation centered at MHz, similar to the GPS GPS signals#L5, Safety of Life|Safety of Life (L5) and Galileo/COMPASS signal E5a;

Global navigation satellite systems - CDMA signals 1 * The open signal L3OCM will use BPSK(10) modulation centered at MHz, similar to Galileo/COMPASS signal E5b.

Global navigation satellite systems - CDMA signals 1 With the introduction of CDMA signals, the constellation will be expanded to 30 active satellites by 2025; this may require eventual deprecation of FDMA signals

Channel access method - Code division multiple access (CDMA)/Spread spectrum multiple access (SSMA) 1 The code division multiple access (CDMA) scheme is based on spread spectrum, meaning that a wider radio spectrum in Hertz is used than the data rate of each of the transferred bit streams, and several message signals are transferred simultaneously over the same carrier frequency, utilizing different spreading codes

Channel access method - Code division multiple access (CDMA)/Spread spectrum multiple access (SSMA) 1 One form is direct sequence spread spectrum (DS-CDMA), used for example in 3G cell phone systems. Each information bit (or each symbol) is represented by a long code sequence of several pulses, called chips. The sequence is the spreading code, and each message signal (for example each phone call) use different spreading code.

Channel access method - Code division multiple access (CDMA)/Spread spectrum multiple access (SSMA) 1 All nodes belonging to the same user (to the same virtual private area network or piconet) use the same frequency hopping sequency synchronously, meaning that they send on the same frequency channel, but CDMA/CA or TDMA is used to avoid collisions within the VPAN

Bell Mobility - CDMA 1 Bell also provides roaming for Sprint Corporation|Sprint, a CDMA carrier in the United States, following a renewed agreement effective June 21, 2006.[ isplay.cfm?article_id=132 Sprint newsroom] Starting in 2012, Bell Mobility and its now-defunct Solo Mobile brand no longer sell CDMA phones, although such devices remain available at Virgin Mobile Canada.

WCDMA 1 It is the basis of Japan's NTT DoCoMo's Freedom of Mobile Multimedia Access|FOMA service and the most- commonly used member of the Universal Mobile Telecommunications System (UMTS) family and sometimes used as a synonym for UMTS.3GPP notes that “there currently existed many different names for the same system (eg FOMA, W-CDMA, UMTS, etc)”; It uses the DS- CDMA channel access method and the Frequency-division duplex|FDD duplexing method to achieve higher speeds and support more users compared to most time division multiple access (TDMA) and time division duplex (TDD) schemes used before.

WCDMA 1 While not an evolutionary upgrade on the airside, it uses the same core network as the 2G Global System for Mobile Communications|GSM networks deployed worldwide, allowing dual mode mobile operation along with GSM/Enhanced Data Rates for GSM Evolution|EDGE; a feature it shares with other members of the UMTS family.

WCDMA - Development 1 Later, W-CDMA was selected as an air interface for UMTS frequency bands|UMTS.

WCDMA - Development 1 As NTT DoCoMo did not wait for the finalisation of the 3G Release 99 specification, their network was initially incompatible with UMTS. However, this has been resolved by NTT DoCoMo updating their network.

WCDMA - Development 1 W-CDMA has then become the dominant technology with 457 commercial networks in 178 countries as of April 2012.[ pdf/HSPA_operator_commitments_ php4 GSM Association HSPA Market update April 2012] Several cdma2000 operators have even converted their networks to W-CDMA for international roaming compatibility and smooth upgrade path to LTE.

WCDMA - Development 1 Despite incompatibilities with existing air- interface standards, the late introduction of this 3G system, and despite the high upgrade cost of deploying an all-new transmitter technology, W-CDMA has become the dominant standard.

WCDMA - Rationale for W-CDMA 1 However, hurdles remain, and cross- licensing of patents between Qualcomm and W-CDMA vendors has not eliminated possible patent issues due to the features of W-CDMA which remain covered by Qualcomm patents.[ 7/04/05/HNqualcommonnokiapatents_1.ht ml Qualcomm says it doesn't need Nokia patents]

WCDMA - Rationale for W-CDMA 1 W-CDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.

WCDMA - Deployment 1 The world's first commercial W-CDMA service, FOMA, was launched by NTT DoCoMo in Japan in

WCDMA - Deployment 1 Elsewhere, W-CDMA deployments are usually marketed under the UMTS brand. See the main Universal_Mobile_Telecommunications_S ystem#Real-world_implementations|UMTS article for more information.

SGSN - WCDMA specific SGSN functions 1 * Tunnel/detunnel downlink/uplink packets toward the Radio Network Controller|radio network controller (RNC)

SGSN - WCDMA specific SGSN functions 1 * Carry out mobility management to the level of an RNC for connected mode mobiles

Direct-sequence CDMA 1 In telecommunications, 'direct-sequence spread spectrum' ('DSSS') is a modulation technique. As with other spread spectrum technologies, the transmitted signal takes up more Bandwidth (signal processing)|bandwidth than the information signal that modulates the carrier or broadcast frequency. The name 'spread spectrum' comes from the fact that the carrier signals occur over the full bandwidth (spectrum) of a device's transmitting frequency. Certain IEEE standards use DSSS signaling.

Direct-sequence CDMA - Features 1 # DSSS Phase modulation|phase- modulates a sine wave Pseudorandomness|pseudorandomly with a continuous string (computer science)|string of pseudorandom noise|pseudonoise (PN) code symbols called Chip (CDMA)|chips, each of which has a much shorter duration than an information bit. That is, each information bit is modulated by a sequence of much faster chips. Therefore, the Chip (CDMA)|chip rate is much higher than the information signal Baud|bit rate.

Direct-sequence CDMA - Features 1 # DSSS uses a signaling (telecommunication)|signal structure in which the sequence of chips produced by the transmitter is already known by the receiver. The receiver can then use the same PN Sequences|PN sequence to counteract the effect of the PN sequence on the received signal in order to reconstruct the information signal.

TD-CDMA 1 'TD-CDMA', an acronym for 'time division multiple access|Time-division - Code division multiple access|CDMA', is a channel access method based on using spread spectrum across multiple Time- division multiplexing|time slots.

Telus Mobility - CDMA 1 The CDMA network remains available for customers with legacy devices.

Telus Mobility - CDMA 1 Most of rural Manitoba, some of Northern Ontario, and a few other rural regions are exclusively served by the CDMA network.

Telus Mobility - CDMA 1 On September 18, 2013, at a conference with investors, TELUS' Chief Financial Officer stated that he expected that TELUS' CDMA network would shut down within two years.[ port-on-business/telus-weighs- mothballing-legacy-wireless-network-to- cut-costs/article / Telus weighs mothballing legacy wireless network to cut costs]

Telus Mobility - CDMA 1 On October 17, 2013, it was revealed that TELUS' CDMA Ev-DO network in British Columbia and Alberta (except Calgary and Edmonton) would be shut down on March 31, 2014.[ elus-aims-to-shut-down-its-cdma-network- in-2015/ TELUS aims to shut down its CDMA network in 2015] With this change, CDMA phone customers would be unable to access the internet using TELUS' network.

Telus Mobility - CDMA 1 Public Mobile, which Telus purchased in 2013, operates a CDMA network. On March 27, 2014, Public Mobile customer were notified that this network would be shut down by August 2014, and that customers wishing to continue service would need to buy phones compatible with Telus' 4G network.[ ort-on-business/teluss-decision-to-shut- public-mobile-angers- consumers/article / Telus’s decision to shut Public Mobile angers consumers]

Sprint PCS - CDMA/1xRTT/EVDO 1 Sprint operates a nationwide CDMA network in the 1900MHz PCS band. In 2006, Sprint's EV-DO Power Vision network reached more than 190 million people. Sprint has then continued upgrading their 3G EV-DO network until it reaches 260million people in

Multiple access - Code division multiple access (CDMA)/Spread spectrum multiple access (SSMA) 1 All nodes belonging to the same user (to the same virtual private area network or piconet) use the same frequency hopping sequency synchronously, meaning that they send on the same frequency channel, but CDMA/CA or TDMA is used to avoid collisions within the VPAN

CDMA Spectral Efficiency 1 'CDMA spectral efficiency' refers to the system spectral efficiency in bit/s/Hz/site or Erlang (unit)|Erlang/MHz/site that can be achieved in a certain CDMA based wireless communication system. CDMA techniques (also known as spread spectrum) are characterized by a very low link spectral efficiency in (bit/s)/Hz as compared to non-spread spectrum systems, but a comparable system spectral efficiency.

CDMA Spectral Efficiency 1 The system spectral efficiency can be improved by radio resource management techniques, resulting in that a higher number of simultaneous calls and higher data rates can be achieved without adding more radio spectrum or more base station sites. This article is about radio resource management specifically for direct- sequence spread spectrum (DS-CDMA) based cellular systems.

CDMA Spectral Efficiency - CDMA based standards 1 * the 3GPP/UMTS 3G radio interfaces WCDMA, HSDPA and HSUPA used globally.

CDMA Spectral Efficiency - CDMA based standards 1 * the 3GPP2 2G standard cdmaOne (IS- 95) and 3G standards CDMA2000 1x and EV-DO|1xEV-DO, used especially in the U.S. and South Korea

CDMA Spectral Efficiency - CDMA based standards 1 The terminology used in this article is firstly based on 3GPP2 standards.

CDMA Spectral Efficiency - CDMA based standards 1 CDMA is not expected to be used in 4G systems, and is not used in pre-4G systems such as 3GPP long term evolution|LTE and WiMAX, but is about to be supplemented by more spectral efficient frequency-domain equalization (FDE) techniques such as OFDMA.

CDMA Spectral Efficiency - Introduction to radio resource management 1 The aim of improving system spectral efficiency is to use limited radio spectrum resources and radio network infrastructure as efficiently as possible

CDMA Spectral Efficiency - Introduction to radio resource management 1 There are many ways of increasing system spectral efficiency. These includes techniques to be implemented at the handset level or at the network level. They include network optimization and vocoder rate encapsulation. Issues faced while deploying these techniques are the cost, upgrade requirements, hardware and software changes (which includes cell phone compatibility corresponding to the changes) to be made and the agreements to be approved from the telecommunication department.

CDMA Spectral Efficiency - Quasi-Linear Interference Cancellation (QLIC) 1 Due to its large transmission power, the Common pilot channel (CPICH) probably consumes 15 to 20 percentage of the forward as well as the reverse link capacity

CDMA Spectral Efficiency - Quasi-Linear Interference Cancellation (QLIC) 1 Along with the forward link, reverse link interference cancellation is also important. Interference will be reduced and the mobiles will have to transmit less power to get the Line-of-sight propagation|line of sight with the base station which will in turn increase the battery life of the mobile.

CDMA Spectral Efficiency - 1/8 rate gating on R-FCH (Reverse fundamental channel) 1 The 1/8 rate Gating (telecommunication)|gating on the reverse fundamental channel (R-FCH) is the method used for gated transmission in a CDMA communication system. A mobile station (mobile phone) in the CDMA communication system transmits a reverse pilot signal at a reverse gating rate which is different from a forward gating rate in a gated mode, and a base station transmits a forward pilot signal at the forward gating rate different from the forward gating rate in a gated mode.

CDMA Spectral Efficiency - 1/8 rate gating on R-FCH (Reverse fundamental channel) 1 When the duty cycle is 1/8, only 1/8 of the whole power control groups in one frame are transmitted. This behavior is not present in any other CDMA modes.

CDMA Spectral Efficiency - 1/8 rate gating on R-FCH (Reverse fundamental channel) 1 Another CDMA invention to provide a device and technique for improving a downlink phone capacity and receiving performance by gating an uplink DPCCH signal in a partial period of the power control group in a mobile communication system. The test set's support for the R- FCH gating mode is disabled (off) by default.

CDMA Spectral Efficiency - 1/8 rate gating on R-FCH (Reverse fundamental channel) 1 If the test set's R-FCH gating mode is enabled (on) and the mobile station (MS) supports the gating mode, the MS will gate the R-FCH/R-Pilot Channel when transmitting at 1/8 rate. This will save around 75% of the power on an average on reverse channels.

CDMA Spectral Efficiency - Radio Configuration 1 The CDMA radio configuration is defined as a combination of forward and reverse traffic channel transmission formats that are characterized by physical layer parameters such as data rates, error- correction codes, modulation characteristics, and spreading factors. The traffic channel may consist of one or more code channels such as fundamental channels and supplemental channels.

CDMA Spectral Efficiency - Quasi-Orthogonal functions (QOF) 1 The forward link of a 3G code-division multiple-access (CDMA) system may become a limiting factor when the number of users increases maximal capacity.

CDMA Spectral Efficiency - Quasi-Orthogonal functions (QOF) 1 The conventional channelization code, Walsh code does not have enough available bits to cope with maximal use. Therefore, the quasi-orthogonal function (QOF), which can process optimal cross- correlation with Walsh code has been used as a method to get around the limitations of the Walsh Codes.

CDMA Spectral Efficiency - Quasi-Orthogonal functions (QOF) 1 To enhance the overall capacity in such scenarios, alternative sets of orthogonal functions called the quasi-orthogonal functions (QOF), which possess optimal minimax cross correlation with Walsh code sets of variable length, have been incorporated in IS

CDMA Spectral Efficiency - Quasi-Orthogonal functions (QOF) 1 This method uses aggregation of multiple quasi-orthogonal functions with a smaller constellation alphabet size for a single user with a joint multi-channel detector. This method is compared with the alternative method for enhancing the maximum throughput using aggregation of a smaller number of Walsh functions, but with a higher constellation alphabet size (multi-level modulation).

CDMA Spectral Efficiency - Quasi-Orthogonal functions (QOF) 1 There have been many industrial and academic discussions on the trade-offs with respect to better methods for increasing capacity in IS-2000/3G systems. QOF introduces high amount of interference in the network channels, thus limiting its benefits.

CDMA Spectral Efficiency - 6 Sectorization 1 There are some places where the utilization of the site is very high and excess softer handoffs occur. For such sites, a 6-sector antenna is one of the solutions, as it provides greater coverage granularity than the traditional 3-sector antenna. Instead of 1 BTS, 2 BTS are used and hence the antennas can be separated from each other by 60 degrees instead of 120 degrees.

CDMA Spectral Efficiency - Antenna diversity 1 Antenna diversity, also known as space diversity (micro-diversity as well as macro- diversity, i.e. soft handover, see below), is any one of several wireless diversity schemes that use two or more antennas to improve the quality and reliability of a wireless link.

CDMA Spectral Efficiency - Antenna diversity 1 Often, especially in urban and indoor environments, there is not a clear line-of- sight (LOS) between transmitter and receiver. Instead the signal is reflected along multiple paths before finally being received. Each of these bounces can introduce phase shifts, time delays, attenuations, and even distortions that can destructively interfere with one another at the aperture of the receiving antenna.

CDMA Spectral Efficiency - Antenna diversity 1 Antenna diversity is especially effective at mitigating these multipath propagation situations. This is because multiple antennas afford a receiver several observations of the same signal. Each antenna will experience a different interference environment. Thus, if one antenna is experiencing a deep fade, it is likely that another has a sufficient signal.

CDMA Spectral Efficiency - Antenna diversity 1 Collectively such a system can provide a robust link. While this is primarily seen in receiving systems (diversity reception), the analog has also proven valuable for transmitting systems (transmit diversity) as well.

CDMA Spectral Efficiency - Antenna diversity 1 Inherently an antenna diversity scheme requires additional hardware and integration versus a single antenna system but due to the commonality of the signal paths a fair amount of circuitry can be shared.

CDMA Spectral Efficiency - Antenna diversity 1 With multiple signals there is a greater processing demand placed on the receiver, which can lead to tighter design requirements of the base station. Typically, however, signal reliability is paramount and using multiple antennas is an effective way to decrease the number of drop-outs and lost connections.

CDMA Spectral Efficiency - 4th Generation Vocoder (4GV) 1 Qualcomm’s fourth generation vocoder (4GV) is a suite of voice speech codecs expected to be used in future 4G networks as well CDMA networks, that allows the network operators to dynamically prioritize voice quality to increase network capacity while maintaining voice quality. Currently, the 4GV suite offers EVRC-B and EVRC- WB.

CDMA Spectral Efficiency - 4th Generation Vocoder (4GV) 1 Enhanced Variable Rate Codec B (EVRC- B) is a speech codec used by CDMA networks. EVRC-B is an enhancement to EVRC and compresses each 20 milliseconds of 8000Hz, 16-bit sampled speech input into output frames of one of the four different sizes: Rate bits, Rate 1/ bits, Rate 1/ bits, Rate 1/ bits.

CDMA Spectral Efficiency - 4th Generation Vocoder (4GV) 1 In addition, there are two zero bit codec frame types: null frames and erasure frames, similar to EVRC. One significant enhancement in EVRC-B is the use of 1/4 rate frames that were not used in EVRC. This provides lower average data rates (ADRs) compared to EVRC, for a given voice quality. The new 4GV Codecs used in CDMA2000 are based on EVRC-B. 4GV is designed to allow service providers to dynamically prioritize voice capacity on their network as required.

CDMA Spectral Efficiency - 4th Generation Vocoder (4GV) 1 The Enhanced Variable Rate Codec (EVRC) is a speech codec used for cellular telephony in cdma2000 systems. EVRC provides excellent speech quality using variable rate coding with 3 possible rates, 8.55, 4.0 and 0.8 kbit/s. However, the Mobile QoS|Quality of Service (QoS) in cdma2000 systems can significantly benefit from a codec which allows tradeoffs between voice quality and network capacity, which cannot be achieved efficiently with the EVRC.

CDMA Spectral Efficiency - Ec/Io optimization 1 Higher combined Ec/Io, lower traffic channel Ec/Io is required and more BTS power is conserved.

CDMA Spectral Efficiency - Ec/Io optimization 1 Eb/No|Ec/Io is a notation used to represent a dimensionless ratio of the average power of a channel, typically the pilot channel, to the total signal power. It is expressed in dB.

CDMA Spectral Efficiency - Forward and reverse link imbalance 1 There are some remote places where BTS signal penetrates but reverse link of mobile cannot reach back to the base station.Solution is like reducing base station antenna height, down tilt, select lower gains, etc.

CDMA Spectral Efficiency - Excessive soft handoff areas 1 There are some areas with more soft handoff than necessary. The handoff parameters has to be reduced to save the base station power.Set higher values of T_ADD and T_DROP, and check the sector coverage should not be too high or too low.

CDMA Spectral Efficiency - Improper RF parameters settings 1 For best quality decrease the FPCH (Forward Pilot Channel) and FER (Frame Error Rate) settings to 1% and for increase the capacity of highly loaded sites, increase the settings of these parameters to more than 3%.

CDMA Spectral Efficiency - Use repeaters for low utilized sectors 1 Some sites have very low utilization and due to coverage issue, a new site is required in nearby areas. Instead of a new site, a Cellular repeater can be used effectively to provide coverage solutions.

Code division multiplexing - Steps in CDMA modulation 1 In CDMA a locally generated code runs at a much higher rate than the data to be transmitted

Code division multiplexing - Steps in CDMA modulation 1 Similarly, in radio CDMA, each group of users is given a shared code

Code division multiplexing - Code division multiplexing (synchronous CDMA) 1 The digital modulation method is analogous to those used in simple radio transceivers

Mobile User Objective System - WCDMA system 1 It converts a commercial third generation (3G) Wideband Code Division Multiple Access (WCDMA) cellular phone system to a military UHF SATCOM radio system using geosynchronous satellites in place of cell towers

AKA (security) - AKA in CDMA 1 'AKA – Authentication and Key Agreement

AKA (security) - AKA in CDMA 1 a.k.a. 3G Authentication, Enhanced Subscriber Authorization (ESA)

AKA (security) - AKA in CDMA 1 The basis for the 3G authentication mechanism, defined as a successor to CAVE-based Authentication, AKA provides procedures for mutual authentication of the Mobile Station (Station (networking)|MS) and serving system. The successful execution of AKA results in the establishment of a security association (i.e., set of security data) between the MS and serving system that enables a set of security services to be provided.

AKA (security) - AKA in CDMA 1 Major advantages of AKA over CAVE-based authentication include:

AKA (security) - AKA in CDMA 1 *Larger authentication keys (128-bit )

AKA (security) - AKA in CDMA 1 *Stronger hash function (SHA-1)

AKA (security) - AKA in CDMA 1 *Support for mutual authentication

AKA (security) - AKA in CDMA 1 *Support for signaling message data integrity

AKA (security) - AKA in CDMA 1 *Support for user data encryption

AKA (security) - AKA in CDMA 1 *Protection from rogue MS when dealing with Removable User Identity Module|R-UIM

AKA (security) - AKA in CDMA 1 AKA is not yet implemented in CDMA2000 networks, although it is expected to be used for IP Multimedia Subsystem|IMS. To ensure interoperability with current devices and partner networks, support for AKA in CDMA networks and handsets will likely be in addition to CAVE-based authentication.

AKA (security) - AKA in CDMA 1 Air interface support for AKA is included in all releases following CDMA2000 Rev C.

AKA (security) - AKA in CDMA 1 TIA-41 MAP support for AKA was defined in TIA-945 (3GPP2 X.S0006), which has been integrated into TIA-41 (3GPP2 X.S0004).

AKA (security) - AKA in CDMA 1 For information on AKA in roaming, see CDG Reference Document #138.

Phone cloning - CDMA cloning 1 Code division multiple access|Code Division Multiple Access (CDMA) mobile telephone cloning involves gaining access to the device's embedded file system /nvm/num directory via specialized software or placing a modified EEPROM into the target mobile telephone, allowing the Electronic serial number (ESN) and/or Mobile equipment identifier|Mobile Equipment Identifier (MEID) of the mobile phone to be changed

CDMA Subscriber Identity Module 1 UICC-Terminal interface Physical and Logical Characteristics for cdma2000 Spread Spectrum Systems

CDMA Subscriber Identity Module - CSIM Application File System 1 The CSIM application contains a file system with a number of parameters needed to operate on cdmaOne/CDMA2000 (CDMA) networks. Each parameter, or a group of related parameters, is specified with a unique identifier with an implicit or explicit length, and is considered a separate Elementary File (EF). The following examples are taken from the 3GPP2 specification. cdma2000 Application on UICC for Spread Spectrum Systems

CDMA Subscriber Identity Module - CSIM Application File System 1 * Received Short Messages (255 bytes maximum per message).

CDMA Subscriber Identity Module - CSIM Application File System 1 * International mobile subscriber identity|IMSI (international mobile subscriber identifier).

CDMA Subscriber Identity Module - CSIM Application File System 1 * Temporary Mobile Subscriber Identity|TMSI (temporary mobile subscriber identifier, for position security).

CDMA Subscriber Identity Module - CSIM Application File System 1 * UIMID (hardware identifier). Will be a pseudo (hashed) value if EUIMID is in use.

CDMA Subscriber Identity Module - CSIM Application File System 1 * EUIMID. Either short form (based on MEID) or long form (based on ICCID).

CDMA Subscriber Identity Module - CSIM Application File System 1 * ICCID. Present even if it is not used as EUIMID.

CDMA Subscriber Identity Module - CSIM Application File System 1 * CDMA2000 home identifiers, such as System_Identification_Number|SID and NID.

CDMA Subscriber Identity Module - CSIM Application File System 1 * CDMA2000 zone-based registration parameters, telling the handset to register when it changes to a new operator-defined zone (System_Identification_Number|SID/NID).

CDMA Subscriber Identity Module - CSIM Application File System 1 * Random parameters (slot cycle index) to use during CSMA access probes.

CDMA Subscriber Identity Module - CSIM Application File System 1 * List of services available. If a service is not indicated as available in the CSIM, the mobile equipment shall not select this service. Examples include Call Control, SMS, BCMCS Broadcast, IP Location, etc. If a service is not in this table, the handset will not provide the service.

CDMA Subscriber Identity Module - CSIM Application File System 1 * Multimode System Selection (MMSS) parameters.

DS-CDMA - Features 1 # DSSS Phase-shift keying|phase-shifts a sine wave Pseudorandomness|pseudorandomly with a continuous string (computer science)|string of pseudorandom noise|pseudonoise (PN) code symbols called Chip (CDMA)|chips, each of which has a much shorter duration than an information bit. That is, each information bit is modulated by a sequence of much faster chips. Therefore, the Chip (CDMA)|chip rate is much higher than the information signal Baud|bit rate.

List of TD-SCDMA networks 1 The following is a list of mobile telephony|mobile telecommunications networks using 3G|third-generation 'TD- SCDMA / UMTS-TDD (LCR)' technology.

List of TD-SCDMA networks - General information 1 * TD-SCDMA / UMTS-TDD (LCR) networks are incompatible with Universal Mobile Telecommunications System#W- CDMA (UTRA-FDD)|W-CDMA / UMTS- FDD and TD-CDMA / UMTS-TDD (HCR) networks.

Nexian - CDMA 1 All of Nexian's Code division multiple access|CDMA phones and smartphones have a similar system with the GSM phones. Some phones use the term NX- FPxxx for phones in partnership with Telkom Indonesia|Telkom's Flexi CDMA service. Phones such as NX-C900 are one of Nexian's CDMA smartphones that uses QWERTY keyboard.

Nokia 6610i - CDMA variant The 'Nokia 6585' is a physically identical variant of the 6610 for CDMA2000 1xRTT networks. Like its GSM cousin, the 6585 comes in a similar form factor, and can be customised with interchangeable face plates.

List of Motorola products - iDEN/CDMA dual-mode a.k.a. Cobra 1 See also: Code division multiple access (CDMA)

Nokia CDMA variant – Nokia The 'Nokia 8270' is a related CDMA model with a similar design to the Asian It operates on the CDMA 1900 frequency. Like the 8250, it features a blue backlight, however, it does not feature an infrared port. In its time, this phone was a great hit with many people.

U.S. Cellular - CDMA/3G network 1 Cellular used analog, then Digital AMPS TDMA cell phones in most markets, but the company started shifting over to 1xRTT CDMA technology in

U.S. Cellular - CDMA/3G network 1 The company offers national 3G coverage through roaming agreements. Native coverage is mainly in the Pacific Northwest, Midwest, parts of the East and New England. Although headquartered in Chicago, U.S. Cellular did not offer service in the Chicago metropolitan area until it acquired territories from PrimeCo Communications between 2002 and 2003, after the formation of Verizon Wireless.

For More Information, Visit: m/itil-2011-foundation- complete-certification-kit- fourth-edition-study-guide- ebook-and-online-course.html m/itil-2011-foundation- complete-certification-kit- fourth-edition-study-guide- ebook-and-online-course.html The Art of Service