Generally speaking, computer memory upgrades (not including Flash memory cards or USB drives) can be divided into two different types:
Type 1: Generic upgrades. These are made by a plethora of manufacturers and are made to a speed and form factor specification, such as a DDR-333 200 pin SO-DIMM, or a DDR2-667 240 pin DIMM. Generic upgrades are made without regard to the particular requirements of the computer they are being installed in. Generic upgrades are usually cheaper and supplied by 1000′s of resellers worldwide.
Type 2: System specific upgrades. (Also known as ‘branded’ memory). This is memory that is made to a particular speed and form factor specification, and further tested to function in particular brand / model computers and motherboards. The most well known manufacturer of system specific upgrades is Kingston.
In recent years other memory manufacturers have also chosen to compete in the branded memory market, such as Transcend, Corsair, A-data, and Patriot. All offer similar guarantees of compatibility, however Kingston is arguably the most trusted brand, especially amongst those who work in the IT sector. Kingston also have close relationships with the major OEM’s like IBM, such that technicians will service onsite Kingston memory products that have been installed in IBM computer systems.
If you purchase a system specific module(s) for your computer, Kingston will guarantee it to be compatible. System specific upgrades are generally a little more expensive than generic upgrades because the design is customized to meet the memory requirements of the computer system the module is designed for. Kingston also also tests the module in the end system using popular applications that people use every day (email clients, web browsers, etc), operating systems and the original equipment manufacturer’s own system diagnostic program.
So, let’s say you own a Dell Latitude D830 model laptop and you want to upgrade the memory. You have referred to your owners manual and you’ve figured out that your computer takes DDR2-667 (also known as PC2-5300) 200-pin SO-DIMMs. You could now just find the retailer with the cheapest DDR2-667 SO-DIMMs on the internet and duly purchase them. I see this as a lottery. Chances are you may be lucky and the modules may work. However, like many people who buy the cheapest memory they can find, and then end up purchasing the correct upgrade from RamCity, you may have problems with modules made using a lower quality manufacturing process. In many cases these people lost their money because their purchase came without any warranty as to compatibility and the reseller argued that their purchase was not faulty, just incompatible.
So, if you are in the market for a RAM upgrade, and want some peace of mind and reassurance that it is going to work the first time, be sure to ask your reseller if they sell system specific memory upgrades. Also check if they offer a guarantee that their modules will work in your computer, or happily refund your money in full.
About the Author
Rod Bland is the owner of RamCity UK, a specialist Computer Memory
Upgrade supply company. RamCity UK ship system-specific upgrades to customers throughout the UK and EU from a dedicated warehouse in Kent, United Kingdom.
Help on laptops. Buying a IBM thinkpap.. good idea?
I like how the ibm thinkpads look, and the fact that they are strong and sturdy.
i find the t42 and 43 for around 200 to 300 dollars and the t60 for 400 or so
now i wanna buy one also becuse i have maybe 500 to spend. i figured i can buy a t43 for 300 and use the rest to upgrade it.
i dont like vista to much and i dont want windows 7. they come xp pro so im fine. the ram on the t43 and 42 is a max of 2gb and 4gb for the t60.
i have my own hard drives i can put in
my question is though would it be wise to do this? buy one and give it more memory and put a bigger hd in? vista takes up 1g ram so i figure xp isnt as much so id be fine with 2gigs ram.
i dont know.. any help? suggestions?
I would suggest that you should definitely do this…..
You should buy a Refurbished IBM T43 laptop in just $300 and secondly with the rest of your money you can simply upgrade it…..
IBM Thinkpad T43
Intel Mobile Centrino 1.86 GHz Processor, 2 GB Ram, 40 GB Harddrive, CD-RW/DVD Drive (COMBO) Drive, WiFi, Ethernet & 56K Modem, Windows XP Professional, 15 inch Display $299
Check out the website link from where I gave you this piece information
UMTS, using W-CDMA, supports maximum theoretical data transfer rates of 21 Mbit/s (with HSDPA), although at the moment users in deployed networks can expect a transfer rate of up to 384 kbit/s for R99 handsets, and 7.2 Mbit/s for HSDPA handsets in the downlink connection. This is still much greater than the 9.6 kbit/s of a single GSM error-corrected circuit switched data channel or multiple 9.6 kbit/s channels in HSCSD (14.4 kbit/s for CDMAOne), andn competition to other network technologies such as CDMA2000, PHS or WLANffers access to the World Wide Web and other data services on mobile devices.
Precursors to 3G are 2G mobile telephony systems, such as GSM, IS-95, PDC, CDMA PHS and other 2G technologies deployed in different countries. In the case of GSM, there is an evolution path from 2G, to GPRS, also known as 2.5G. GPRS supports a much better data rate (up to a theoretical maximum of 140.8 kbit/s, though typical rates are closer to 56 kbit/s) and is packet switched rather than connection oriented (circuit switched). It is deployed in many places where GSM is used. E-GPRS, or EDGE, is a further evolution of GPRS and is based on more modern coding schemes. With EDGE the actual packet data rates can reach around 180 kbit/s (effective). EDGE systems are often referred as “2.75G Systems”.
Since 2006, UMTS networks in many countries have been or are in the process of being upgraded with High Speed Downlink Packet Access (HSDPA), sometimes known as 3.5G. Currently, HSDPA enables downlink transfer speeds of up to 21 Mbit/s. Work is also progressing on improving the uplink transfer speed with the High-Speed Uplink Packet Access (HSUPA). Longer term, the 3GPP Long Term Evolution project plans to move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up, using a next generation air interface technology based upon Orthogonal frequency-division multiplexing.
The first national consumer UMTS networks launched in 2002 with a heavy emphasis on telco-provided mobile applications such as mobile TV and video calling. The high data speeds of UMTS are now most often utilised for Internet access: experience in Japan and elsewhere has shown that user demand for video calls is not high, and telco-provided audio/video content has declined in popularity in favour of high-speed access to the World Wide Web – either directly on a handset or connected to a computer via Wi-Fi, Bluetooth, Infrared or USB.
Technology
UMTS combines three different air interfaces, GSM’s Mobile Application Part (MAP) core, and the GSM family of speech codecs.
Air interfaces
UMTS provides several different terrestrial air interfaces, called UMTS Terrestrial Radio Access (UTRA). All air interface options are part of ITU’s IMT-2000. In the currently most popular variant for cellular mobile telephones, W-CDMA (IMT Direct Spread) is used.
Please note that the terms W-CDMA, TD-CDMA and TD-SCDMA are misleading. While they suggest covering just a channel access method (namely a variant of CDMA), they are actually the common names for the whole air interface standards.
Non-terrestrial radio access networks are currently under research.
W-CDMA (UTRA-FDD)
Main article: W-CDMA (UMTS)
UMTS transmitter on the roof of a building
W-CDMA uses the DS-CDMA channel access method with a pair of 5 MHz channels. In contrast, the competing CDMA2000 system uses one or more arbitrary 1.25 MHz 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).
The specific frequency bands originally defined by the UMTS standard are 18852025 MHz for the mobile-to-base (uplink) and 21102200 MHz for the base-to-mobile (downlink). In the US, 17101755 MHz and 21102155 MHz will be used instead, as the 1900 MHz band was already utilized. While UMTS2100 is the most widely-deployed UMTS band, some countries’ UMTS operators use the 850 MHz and/or 1900 MHz bands (independently, meaning uplink and downlink are within the same band), notably in the US by AT&T Mobility, New Zealand by Telecom New Zealand on the XT Mobile Network and in Australia by Telstra on the Next G network.
W-CDMA is a part of IMT-2000 as IMT Direct Spread.
UTRA-TDD HCR
Main article: UTRA-TDD HCR
UMTS-TDD’s air interfaces that use the TD-CDMA channel access technique are standardized as UTRA-TDD HCR, which uses increments of 5 MHz of spectrum, each slice divided into 10ms frames containing fifteen time slots (1500 per second). The time slots (TS) are allocated in fixed percentage for downlink and uplink. TD-CDMA is used to multiplex streams from or to multiple transceivers. Unlike W-CDMA, it does not need separate frequency bands for up- and downstream, allowing deployment in tight frequency bands.
TD-CDMA is a part of IMT-2000 as IMT CDMA TDD.
TD-SCDMA (UTRA-TDD 1.28 Mcps Low Chip Rate)
Main article: TD-SCDMA
TD-SCDMA uses the TDMA channel access method combined with an adaptive synchronous CDMA component on 1.6 MHz slices of spectrum, allowing deployment in even tighter frequency bands than TD-CDMA. However, the main incentive for development of this Chinese-developed standard was avoiding or reducing the license fees that have to be paid to non-Chinese patent owners. 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.
Like TD-CDMA, it is known as IMT CDMA TDD within IMT-2000.
Radio access network
Main article: UTRAN
UMTS also specifies the UMTS Terrestrial Radio Access Network (UTRAN), which is composed of multiple base stations, possibly using different terrestrial air interface standards and frequency bands.
UMTS and GSM/EDGE can share a Core Network (CN), making UTRAN an alternative radio access network to GERAN (GSM/EDGE RAN), and allowing (mostly) transparent switching between the RANs according to available coverage and service needs. Because of that, UMTS’ and GSM/EDGE’s radio access networks are sometimes collectively referred to as UTRAN/GERAN.
UMTS networks are often combined with GSM/EDGE, the later of which is also a part of IMT-2000.
The UE (User Equipment) interface of the RAN (Radio Access Network) primarily consists of RRC (Radio Resource Control), RLC (Radio Link Control) and MAC (Media Access Control) protocols. RRC protocol handles connection establishment, measurements, radio bearer services, security and handover decisions. RLC protocol primarily divides into three Modes – Transparent Mode (TM), Unacknowledge Mode (UM), Acknowledge Mode (AM). The functionality of AM entity resembles TCP operation where as UM operation resembles UDP operation. In TM mode, data will be sent to lower layers without adding any header to SDU of higher layers. MAC handles the scheduling of data on air interface depending on higher layer (RRC) configured parameters.
Set of properties related to data transmission is called Radio Bearer (RB). This set of properties will decide the maximum allowed data in a TTI (Transmission Time Interval). RB includes RLC information and RB mapping. RB mapping decides the mapping between RB<->logical channel<->transport channel. Signaling message will be send on Signaling Radio Bearers (SRBs) and data packets (either CS or PS) will be sent on data RBs. RRC and NAS messages will go on SRBs.
Security includes two procedures: integrity and ciphering. Integrity validates the resource of message and also make sure that no one (third/unknown party) on radio interface has not modified message. Ciphering make sure that no one listens your data on air interface. Both integrity and ciphering will be applied for SRBs where as only ciphering will be applied for data RBs.
Core network
Main article: Mobile Application Part
With Mobile Application Part, UMTS uses the same core network standard as GSM/EDGE. This allows a simple migration for exiting GSM operators. However, the migration path to UMTS is still costly: while much of the core infrastructure is shared with GSM, the cost of obtaining new spectrum licenses and overlaying UMTS at existing towers is high.
The CN can be connected to various backbone networks like the Internet, ISDN. UMTS (and GERAN) include the three lowest layers of OSI model. The network layer (OSI 3) includes the Radio Resource Management protocol (RRM) that manages the bearer channels between the mobile terminals and the fixed network, including the handovers.
Spectrum allocation
Main article: UMTS frequency bands
Over 130 licenses have already been awarded to operators worldwide (as of December 2004), specifying W-CDMA radio access technology that builds on GSM. In Europe, the license process occurred at the tail end of the technology bubble, and the auction mechanisms for allocation set up in some countries resulted in some extremely high prices being paid for the original 2100 MHz licenses, notably in the UK and Germany. In Germany, bidders paid a total 50.8 billion for six licenses, two of which were subsequently abandoned and written off by their purchasers (Mobilcom and the Sonera/Telefonica consortium). It has been suggested that these huge license fees have the character of a very large tax paid on future income expected many years down the road. In any event, the high prices paid put some European telecom operators close to bankruptcy (most notably KPN). Over the last few years some operators have written off some or all of the license costs. More recently, a carrier in Finland has begun using 900 MHz UMTS in a shared arrangement with its surrounding 2G GSM base stations, a trend that is expected to expand over Europe in the next 13 years.
The 2100 MHz UMTS spectrum allocated in Europe is already used in North America. The 1900 MHz range is used for 2G (PCS) services, and 2100 MHz range is used for satellite communications. Regulators have, however, freed up some of the 2100 MHz range for 3G services, together with the 1700 MHz for the uplink. UMTS operators in North America who want to implement a European style 2100/1900 MHz system will have to share spectrum with existing 2G services in the 1900 MHz band.
AT&T Wireless launched UMTS services in the United States by the end of 2004 strictly using the existing 1900 MHz spectrum allocated for 2G PCS services. Cingular acquired AT&T Wireless in 2004 and has since then launched UMTS in select US cities. Cingular renamed itself AT&T and is rolling out some cities with a UMTS network at 850 MHz to enhance its existing UMTS network at 1900 MHz and now offers subscribers a number of UMTS 850/1900 phones.
T-Mobile’s rollout of UMTS in the US will focus on the 2100/1700 MHz bands, whereas UMTS coverage in Canada is being provided on the 850 MHz band of the Rogers Wireless network. In 2008, Australian telco Telstra replaced its existing CDMA network with a national 3G network, branded as NextG, operating in the 850 MHz band. Telstra currently provides UMTS service on this network, and also on the 2100 MHz UMTS network, through a co-ownership of the owning and administrating company 3GIS. This company is also co-owned by Hutchison 3G Australia, and this is the primary network used by their customers. Optus is currently rolling out a 3G network operating on the 2100 MHz band in cities and most large towns, and the 900 MHz band in regional areas. Vodafone is also building a 3G network using the 900 MHz band. In India BSNL has started its 3G services since October 2009 beginning with the larger cities and then expanding over to smaller cities. The 850 MHz and 900 MHz bands provide greater coverage compared to equivalent 1700/1900/2100 MHz networks, and are best suited to regional areas where greater distances separate subscriber and base station.
Carriers in South America are now also rolling out 850 MHz networks.
Interoperability and global roaming
UMTS phones (and data cards) are highly portablehey have been designed to roam easily onto other UMTS networks (if the providers have roaming agreements in place). In addition, almost all UMTS phones are UMTS/GSM dual-mode devices, so if a UMTS phone travels outside of UMTS coverage during a call the call may be transparently handed off to available GSM coverage. Roaming charges are usually significantly higher than regular usage charges.
Most UMTS licensees consider ubiquitous, transparent global roaming an important issue. To enable a high degree of interoperability, UMTS phones usually support several different frequencies in addition to their GSM fallback. Different countries support different UMTS frequency bands Europe initially used 2100 MHz while the most carriers in the USA use 850Mhz and 1900Mhz. T-mobile has launched a network in the US operating at 1700 MHz (uplink) /2100 MHz (downlink), and these bands are also being adopted elsewhere in the Americas. A UMTS phone and network must support a common frequency to work together. Because of the frequencies used, early models of UMTS phones designated for the United States will likely not be operable elsewhere and vice versa. There are now 11 different frequency combinations used around the worldncluding frequencies formerly used solely for 2G services.
UMTS phones can use a Universal Subscriber Identity Module, USIM (based on GSM’s SIM) and also work (including UMTS services) with GSM SIM cards. This is a global standard of identification, and enables a network to identify and authenticate the (U)SIM in the phone. Roaming agreements between networks allow for calls to a customer to be redirected to them while roaming and determine the services (and prices) available to the user. In addition to user subscriber information and authentication information, the (U)SIM provides storage space for phone book contact. Handsets can store their data on their own memory or on the (U)SIM card (which is usually more limited in its phone book contact information). A (U)SIM can be moved to another UMTS or GSM phone, and the phone will take on the user details of the (U)SIM, meaning it is the (U)SIM (not the phone) which determines the phone number of the phone and the billing for calls made from the phone.
Japan was the first country to adopt 3G technologies, and since they had not used GSM previously they had no need to build GSM compatibility into their handsets and their 3G handsets were smaller than those available elsewhere. In 2002, NTT DoCoMo’s FOMA 3G network was the first commercial UMTS networksing a pre-release specification, it was initially incompatible with the UMTS standard at the radio level but used standard USIM cards, meaning USIM card based roaming was possible (transferring the USIM card into a UMTS or GSM phone when travelling). Both NTT DoCoMo and SoftBank Mobile (which launched 3G in December 2002) now use standard UMTS.
Handsets and modems
T-Mobile UMTS PC Card modem
The Nokia 6650, an early UMTS handset
All of the major 2G phone manufacturers (that are still in business) are now manufacturers of 3G phones. The early 3G handsets and modems were specific to the frequencies required in their country, which meant they could only roam to other countries on the same 3G frequency (though they can fall back to the older GSM standard). Canada and USA have a common share of frequencies, as do most European countries. The article UMTS frequency bands is an overview of UMTS network frequencies around the world.
Using a cellular router, PCMCIA or USB card, customers are able to access 3G broadband services, regardless of their choice of computer (such as a tablet PC or a PDA). Some software installs itself from the modem, so that in some cases absolutely no knowledge of technology is required to get online in moments. Using a phone that supports 3G and Bluetooth 2.0, multiple Bluetooth-capable laptops can be connected to the Internet. Some smartphones can also act as a mobile WLAN access point.
There are almost no 3G phones or modems available supporting all 3G frequencies (UMTS850/900/1700/1900/2100 MHz). However, many phones are offering more than one band which still enables extensive roaming. For example, a tri-band chipset operating on 850/1900/2100 MHz, such as that found in Apple’s iPhone, allows usage in the majority of countries where UMTS-FDD is deployed.
Other competing standards
The main competitor to UMTS is CDMA2000 (IMT-MC), which is developed by the 3GPP2. Unlike UMTS, CDMA2000 is an evolutionary upgrade to an existing 2G standard, cdmaOne, and is able to operate within the same frequency allocations. This and CDMA2000′s narrower bandwidth requirements make it easier to deploy in existing spectra. In some, but not all, cases, existing GSM operators only have enough spectrum to implement either UMTS or GSM, not both. For example, in the US D, E, and F PCS spectrum blocks, the amount of spectrum available is 5 MHz in each direction. A standard UMTS system would saturate that spectrum. Where CDMA2000 is deployed, it usually co-exists with UMTS. In many markets however, the co-existence issue is of little relevance, as legislative hurdles exist to co-deploying two standards in the same licensed slice of spectrum.
Another competitor to UMTS is EDGE (IMT-SC), which is an evolutionary upgrade to the 2G GSM system, leveraging existing GSM spectrums. It is also much easier, quicker, and considerably cheaper for wireless carriers to “bolt-on” EDGE functionality by upgrading their existing GSM transmission hardware to support EDGE than having to install almost all brand-new equipment to deliver UMTS. However, being developed by 3GPP just as UMTS, EDGE is not a true competitor. Instead, it is used as a temporary solution preceding UMTS roll-out or as a complement for rural areas. This is facilitated by the fact that GSM/EDGE and UMTS specification are jointly developed and rely on the same core network, allowing dual-mode operation including vertical handovers.
China’s TD-SCDMA standard is often seen as a competitor, too. TD-SCDMA has been added to UMTS’ Release 4 as UTRA-TDD 1.28 Mcps Low Chip Rate (UTRA-TDD LCR). Unlike TD-CDMA (UTRA-TDD 3.84 Mcps High Chip Rate, UTRA-TDD HCR) which complements W-CDMA (UTRA-FDD), it is suitable for both micro and macro cells. However, the lack of vendors’ support is preventing it from being a real competitor.
While DECT is technically capable of competing with UMTS and other cellular networks in densely-populated, urban areas, it has only been deployed for domestic cordless phones and private in-house networks.
All of these competitors have been accepted by ITU as part of the IMT-2000 family of 3G standards, along with UMTS-FDD.
On the Internet access side, competing systems include WiMAX and Flash-OFDM.
Migrating from GPRS to UMTS
From GPRS network, the following network elements can be reused:
Home Location Register (HLR)
Visitor Location Register (VLR)
Equipment Identity Register (EIR)
Mobile Switching Center (MSC) (vendor dependent)
Authentication Center (AUC)
Serving GPRS Support Node (SGSN) (vendor dependent)
Gateway GPRS Support Node (GGSN)
From Global Service for Mobile (GSM) communication radio network, the following elements cannot be reused
Base station controller (BSC)
Base transceiver station (BTS)
They can remain in the network and be used in dual network operation where 2G and 3G networks co-exist while network migration and new 3G terminals become available for use in the network.
The UMTS network introduces new network elements that function as specified by 3GPP:
Node B (base station)
Radio Network Controller (RNC)
Media Gateway (MGW)
The functionality of MSC and SGSN changes when going to UMTS. In a GSM system the MSC handles all the circuit switched operations like connecting A- and B-subscriber through the network. SGSN handles all the packet switched operations and transfers all the data in the network. In UMTS the Media gateway (MGW) take care of all data transfer in both circuit and packet switched networks. MSC and SGSN control MGW operations. The nodes are renamed to MSC-server and GSN-server.
Problems and issues
Some countries, including the United States and Japan, have allocated spectrum differently from the ITU recommendations, so that the standard bands most commonly used for UMTS (UMTS-2100) have not been available. In those countries, alternative bands are used, preventing the interoperability of existing UMTS-2100 equipment, and requiring the design and manufacture of different equipment for the use in these markets. As is the case with GSM900 today, standard UMTS 2100 MHz equipment will not work in those markets. However, it appears as though UMTS is not suffering as much from handset band compatibility issues as GSM did, as many UMTS handsets are multi-band in both UMTS and GSM modes. Quad-band GSM (850, 900, 1800, and 1900 MHz bands) and tri-band UMTS (850, 1900, and 2100 MHz bands) handsets are becoming more commonplace.
The early days of UMTS saw rollout hitches in many countries. Overweight handsets with poor battery life were first to arrive on a market highly sensitive to weight and form factor. The Motorola A830, a debut handset on Hutchison’s 3 network, weighed more than 200 grams and even featured a detachable camera to reduce handset weight. Another significant issue involved call reliability, related to problems with handover from UMTS to GSM. Customers found their connections being dropped as handovers were possible only in one direction (UMTS GSM), with the handset only changing back to UMTS after hanging up. In most networks around the world this is no longer an issue.
Compared to GSM, UMTS networks initially required a higher base station density. For fully-fledged UMTS incorporating video on demand features, one base station needed to be set up every 11.5 km (0.620.93 mi). This was the case when only the 2100 MHz band was being used, however with the growing use of lower-frequency bands (such as 850 and 900 MHz) this is no longer so. This has led to increasing rollout of the lower-band networks by operators since 2006.
Even with current technologies and low-band UMTS, telephony and data over UMTS is still more power intensive than on comparable GSM networks. Apple, Inc. cited UMTS power consumption as the reason that the first generation iPhone only supported EDGE. Their release of the iPhone 3G quotes talk time on UMTS as half that available when the handset is set to use GSM. As battery and network technology improves, this issue is diminishing.
Releases
The evolution of UMTS progresses according to planned releases. Each release is designed to introduce new features and improve upon existing ones.
Release ’99
Bearer services
64 kbit/s circuit switched
384 kbit/s packet switched
Location services
Call services: compatible with Global System for Mobile Communications (GSM), based on Universal Subscriber Identity Module (USIM)
Release 4
Edge radio
Multimedia messaging
MExE (Mobile Execution Environment)
Improved location services
IP Multimedia Services (IMS)
Release 5
IP Multimedia Subsystem (IMS)
IPv6, IP transport in UTRAN
Improvements in GERAN, MExE, etc
HSDPA
Release 6
WLAN integration
Multimedia broadcast and multicast
Improvements in IMS
HSUPA
Fractional DPCH
Release 7
Enhanced L2
64 QAM , MIMO
VoIP over HSPA
CPC – continuous packet connectivity
See also
List of Deployed UMTS networks
3G
3GPP: the body that manages the UMTS standard.
3GPP Long Term Evolution, the 3GPP project to evolve UMTS towards 4G capabilities.
GAN/UMA: A standard for running GSM and UMTS over wireless LANs.
HSDPA, HSUPA: updates to the W-CDMA air interface.
PDCP
Subscriber Identity Module
UMTS-TDD: a variant of UMTS largely used to provide wireless Internet service.
UMTS frequency bands
W-CDMA: the primary air interface standard used by UMTS.
W-CDMA 2100
Other, non-UMTS, 3G and 4G standards:
CDMA2000: evolved from the cmdaOne (also known as IS-95, or “CDMA”) standard, managed by the 3GPP2
FOMA
TD-SCDMA
WiMAX: a newly emerging wide area wireless technology.
UMTS is an evolution of the GSM mobile phone standard.
GSM
GPRS
EDGE
ETSI
Other useful information
Mobile modem
Spectral efficiency comparison table
Code Division Multiple Access (CDMA)
Common pilot channel or CPICH, a simple synchronisation channel in WCDMA.
Multiple-input multiple-output (MIMO) is the major issue of multiple antenna research.
Wi-Fi: a local area wireless technology that is complementary to UMTS.
List of device bandwidths
Operations and Maintenance Centre
Radio Network Controller
UMTS security
Literature
Martin Sauter: Communication Systems for the Mobile Information Society, John Wiley, September 2006, ISBN 0-470-02676-6
Ahonen and Barrett (editors), Services for UMTS (Wiley, 2002) first book on the services for 3G, ISBN 978-0471485506
Holma and Toskala (editors), WCDMA for UMTS, (Wiley, 2000) first book dedicated to 3G technology, ISBN 978-0471720515
Kreher and Ruedebusch, UMTS Signaling: UMTS Interfaces, Protocols, Message Flows and Procedures Analyzed and Explained (Wiley 2007), ISBN 978-0470065334
Laiho, Wacker and Novosad, Radio Network Planning and Optimization for UMTS (Wiley, 2002) first book on radio network planning for 3G, ISBN 978-0470015759
Notes
^ The term W-CDMA usually refers to UMTS’ main air interface, UTRA-FDD, or networks which only operate on UTRA-FDD. However, there are rare instances where it is used in a broader sense, as a synonym for UMTS or any UMTS air interface. For example, 3GPP refers to b]oth Frequency Division Duplex (FDD) and Time Division Duplex (TDD) variants of W-CDMA, i.e. UTRA-FDD and UTRA-TDD.
References
^ a b 3GPP notes that here currently existed many different names for the same system (eg FOMA, W-CDMA, UMTS, etc); 3GPP. “Draft summary minutes, decisions and actions from 3GPP Organizational Partners Meeting#6, Tokyo, 9 October 2001″ (PDF). pp. 7. http://www.3gpp.org/ftp/op/OP_07/DOCS/pdf/OP6_13r1.pdf.
^ Tindal, Suzanne (8 December 2008). “Telstra boosts Next G to 21Mbps”. ZDNet Australia. http://www.zdnet.com.au/news/communications/soa/Telstra-boosts-Next-G-to-21Mbps/0,130061791,339293706,00.htm. Retrieved 2009-03-16.
^ ITU-D Study Group 2. “Guidelines on the smooth transition of existing mobile networks to IMT-2000 for developing countries (GST); Report on Question 18/2″. pp. 4, 2528. http://www.itu.int/dms_pub/itu-d/opb/stg/D-STG-SG02.18-1-2006-PDF-E.pdf. Retrieved 2009-06-15.
^ The FCC’s Advanced Wireless Services bandplan
^ Forkel et al. (2002). “Performance Comparison Between UTRA-TDD High Chip Rate And Low Chip Rate Operation”. http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.11.3672. Retrieved 2009-02-16.
^ Siemens (2004-06-10). “TD-SCDMA Whitepaper: the Solution for TDD bands” (pdf). TD Forum. pp. 69. http://www.tdscdma-forum.org/en/pdfword/200511817463050335.pdf. Retrieved 2009-06-15.
^ Hsiao-Hwa Chen (2007), John Wiley and Sons, pp. 105106, ISBN 978-047002294-8
Mobile WiMAX (IEEE 802.16e-2005) Flash-OFDM IEEE 802.20
4G (IMT-Advanced)
3GPP family
LTE Advanced
WiMAX family
IEEE 802.16m
Related articles
History Cellular network theory List of standards Comparison of standards Spectral efficiency comparison table Cellular frequencies GSM frequency bands UMTS frequency bands Mobile broadband
Categories: 3rd Generation Partnership Project standards | Universal Mobile Telecommunications System | 2002 introductions | VideotelephonyHidden categories: Articles with unsourced statements from July 2008 | All articles with unsourced statements | Wikipedia references cleanup from July 2008 | Articles lacking reliable references from January 2008 About the Author
Okay so maybe i am in the stone age but we are looking to get wireless internet for out laptop. We are looking for something that uses an air card so far we have found that cingular has an air card for about 75 and unlimited internet for 70 per month per card! Is this a good deal or are there better options out there if so please help not sure what to do! Thanks so much!
I have done that before too. Are they able to see any of what you do online! I am afraid that personal information will be viewable like i said i am in the stone age!
does cox and charter offer wireless internet via air cards? We have direct tv and they do not offer wireless in our area i have contacted them before and they sent me to this other company they were associated with and they told me it would cost me 600 to come and install a antenna i asked them if they were pshyco that this was a residence not a business? They were serious by the way!
Do not steal your Wi-Fi from a neighbor, people that steal need a dose of their own medicine, seriously. Ugh.
Do not go with wireless from a cellular company, it’s expensive and the connection is crap. Most broadband providers offer wireless, so depending on where you live that could be COX, Time Warner, or Comcast.
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My wife’s laptop doesn’t react to having an ac adapter plugged in, but it can still run off of battery. (I charge her battery in my laptop and all is well, but that gets old quick.)
Any ideas as to what could be causing this?
I popped it open and didn’t notice anything popped or burnt, all the traces seem in tact and the capacitors are happily sitting there without so much as a bead of capci-juice running down the side.
I’m hoping to be told “oh, that problem, just shake it this way, spray some air here, and off you go”, but so far HP has just been telling me it is a $400 job and I have to wait a month to get it back.
here are a few things that I’d try:
Try your friend’s AC power adaptor(Dell PA-1900-05D AC Adapter) in your laptop, that’ll rule out a broken connecter there.
Charge your battery using his laptop, that should give you some juice to work with.
Check the internal connecter while the adapter’s plugged in, make sure power’s getting to the board.
Check for dead capacitors, the internal power gubbins could be b0rked.
just make sure the power adapter isn’t shot or the pin has fallen out, this problem is quite common on hp laptops
Check the ac plug on the laptop. In a lot of cases this is broken and yes will probably cost a good bit (alot of cases it means a new motherboard)…
Is this a new laptop or an older one? After two and a half years, my laptop’s AC adapter went bad. There are stress points at various points on an adapter. Go to udtek.com and buy a universal power adapter. They usually come with a transformer, an AC plug, and another cable that goes to the computer. It should come with a variety of plugs for various laptop brands.
Buy one (I use a Targus adapter) which is capable of putting out an equal or greater power output as the one your wife has. It should say it on the adapter itself. I don’t remember how I determined my laptop’s power requirements. I think I took it from the battery’s voltage and amperage stats.
Anyways, if this doesn’t work, then you can rule out the AC adapter and figure out what to do next. But changes are that your AC adapter will fail sooner than the laptop’s motherboard power plug header.
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Udtek.com delivers high quality laptop batteries, laptop AC adapters, Laptop keyboards, Lcd chargers, DVD drivers, Scooter chargers and more. Our unique product lines of over 1000 diverse accessory power products and replacement batteries and adapters provide our customers with an extensive selection of the best quality products available.
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With the boom in the IT sector, Desktop PCs came in the market. Computer literacy became a buzz word. Then multinational companies came into the picture. Manual works were replaced by computers to gain more efficiency and security. At present, the scenario has not changed a lot as computers have become a part of everyone’s life. The only thing that has changed a lot is the attitude towards work.
How comfortable it would be if you had a portable device like your PC that could be taken anywhere. It was a dream come true sort of thing with the introduction of Laptops. Inspired by the design of a Japanese lunch box, Laptops are computer systems, which are lightweight and can be easily carried away anywhere. Leading companies like HP, Lenovo, IBM, Del, Sony, etc., have launched laptops in the global market. But the success of products depend on price and quality of the product. Among these established companies, Compaq has brought some excellent laptop models that are affordable and offer multitude of features to suit your personal and professional world.
Compaq laptops often called as notebooks are among the top selling products in the IT industry. These laptops incorporate all the latest softwares and applications to keep you ahead of time. Empowered with Intel Celeron Processor, 80GB internal HDD, wireless technologies, video RAM and Optical drive driver software – you can manage your professional world efficiently. In addition, Compaq laptops come equipped with latest Windows Vista Home basic and premium OS.
The physical appearance of these Compaq laptops are very attractive and you would love to work with it. Open the flap and you will find a vibrant screen and keyboard. The design ergonomics of the device is very user-friendly. Also, the weight of the device is very less including battery. Carry your Compaq laptop to your office or anywhere you go. Manage your work and after work, play or watch movies to relax your mind.
About the Author
Raina Kelsey is a gadget expert and writes about the latest gadgets in the market.
I have a compaq laptop and something’s wrong with it.?
I have a compaq laptop, I’m not sure what exact model it is, but it’s a compaq laptop. It recently started a thing where I’ll turn it on, and it will go to the loading screen, and it will not go past there, it will stay on the loading screen until you shut it off. The thing is, when you launch startup repair, and it finishes, it will turn on, and I’ll get into my account, but then five minutes later, it will either freeze and I’ll have to shut it off, or it’ll crash, and the next time I turn it on it won’t go past the loading screen. What is wrong with my computer???
For your situation I think the best way is if you reformat your hard drive. Before you do, make sure you back up all your important files and transfer them to a new hard drive.
This is a device that allows you to do so:
http://www.topmicrousa.com/bt-300.html
You connect the old hard drive to this device, and then the device to a another computer or laptop via USB. You would then be able to access all the files on it.
I got the device off a PC World Magazine Article.
Best of luck!
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