Number of Connections, GSM

GPRS (General Packet Radio Service) is the world's most ubiquitous wireless data service, available now with almost every GSM network. GPRS is a connectivity solution based on Internet Protocols that supports a wide range of enterprise and consumer applications. With throughput rates of up to 40 kbit/s, users have a similar access speed to a dial-up modem, but with the convenience of being able to connect from anywhere. GPRS customers enjoy advanced, feature-rich data services such as color Internet browsing, e-mail on the move, powerful visual communications such as video streaming, multimedia messages and location-based services.

For operators, the adoption of GPRS is a fast and cost-effective strategy that not only supports the real first wave of mobile Internet services, but also represents a big step towards 3GSM (or wideband-CDMA) networks and services.

GPRS Class Types

The class of the device determines the speed at which GPRS can be used.
For example, the majority of GPRS terminals will be able to download data at speeds of up to 24Kbps (kilobytes per second). At the higher end, speeds are theoretically possible up to 171.2 kbit/sec when 8 slots are assigned at the same time to a single user. In reality 40-50Kbps.
PC cards capable of GPRS will send data up to speeds of 48Kbps.

Compare this to current data speeds available:

Further enhancements to GSM networks are provided by Enhanced Data rates for GSM Evolution (EDGE) technology. EDGE provides up to three times the data capacity of GPRS. Using EDGE, operators can handle three times more subscribers than GPRS; triple their data rate per subscriber, or add extra capacity to their voice communications. EDGE uses the same TDMA (Time Division Multiple Access) frame structure, logic channel and 200kHz carrier bandwidth as today's GSM networks, which allows it to be overlaid directly onto an existing GSM network. For many existing GSM/GPRS networks, EDGE is a simple software-upgrade.

EDGE allows the delivery of advanced mobile services such as the downloading of video and music clips, full multimedia messaging, high-speed colour Internet access and e-mail on the move.

Due to the very small incremental cost of including EDGE capability in GSM network deployment, virtually all new GSM infrastructure deployments are also EDGE capable and nearly all new mid- to high-level GSM devices also include EDGE radio technology. The Global mobile Suppliers Association (GSA) states that, as of November 2006, there were 156 commercial GSM/EDGE networks in 92 countries, out of a total of 213 GSM/EDGE deployments in 118 countries

W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network W-CDMA is the higher speed transmission protocol used in the Japanese FOMA system and in the UMTS system, an advanced 3G system, designed as a replacement for the aging 2G GSM networks deployed worldwide.
More technically, W-CDMA is a wideband spread-spectrum mobile air interface that utilizes the direct sequence Code Division Multiple Access signalling method (or CDMA) to achieve higher speeds and support more users compared to the older TDMA signalling method of GSM networks. W-CDMA is a competitor to CDMA2000.

Development
W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA Later NTT DoCoMo submitted the specification to the International Telecommunication Union (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards, as an alternative to CDMA2000, EDGE, and the short range DECT system. Later, W-CDMA was selected as the air interface for UMTS, the 3G successor to GSM.

Code Division Multiple Access communication networks have been developed by a number of companies over the years, but development of cell-phone networks based on CDMA (prior to W-CDMA) was dominated by Qualcomm, the first company to succeed in developing a practical and cost-effective CDMA implementation for consumer cell phones, its early IS-95 air interface standard. IS-95 evolved into the current CDMA2000 (IS-856/IS-2000) standard.
In the late 1990s, NTT DoCoMo began work on a new wide-band CDMA air interface for their planned 3G network FOMA. FOMA's air interface, called W-CDMA, was selected as the air interface for UMTS, a newer W-CDMA based system designed to be an easier upgrade for European GSM networks compared to FOMA. FOMA and UMTS use essentially the same air interface, but are different in other ways; thus, handsets are not 100% compatible between FOMA and UMTS, but roaming is supported.

Qualcomm created an experimental wideband CDMA system called CDMA2000 3x which unified the W-CDMA (3GPP) and CDMA2000 (3GPP2) network technologies into a single design for a worldwide standard air interface. Compatibility with CDMA2000 would have beneficially enabled roaming on existing networks beyond Japan, since Qualcomm CDMA2000 networks are widely deployed, especially in the Americas, with coverage in 58 countries in 2006. However, divergent requirements resulted in the W-CDMA standard being retained and deployed.
Despite incompatabilities 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 been adopted and deployed rapidly, especially in Japan, Europe and Asia, and is already deployed in over 55 countries in 2006.

Rationale for W-CDMA
W-CDMA transmits on a pair of 5 Mhz wide radio channels, while CDMA2000 transmits on one or several pairs of 1.25 MHz radio channels. Though W-CDMA does use a direct sequence CDMA transmission technique like CDMA2000, W-CDMA is not simply a wideband version of CDMA2000. The W-CDMA system is a new design by NTT DoCoMo, and it differs in many respects from CDMA2000. From an engineering point of view, W-CDMA provides a different balance of costs vs. capacity vs. performance vs. density, and promises to achieve a benefit of reduced cost for video phone handsets.

W-CDMA may also be better suited for deployment in the very dense cities of Europe and Asia. And cross-licencing of patents between Qualcomm and W-CDMA vendors has eliminated possible patent issues due to the features of W-CDMA which remain covered by Qualcomm patents.
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.

What is? DMB

Digital Multimedia Broadcasting (DMB) is a digital radio transmission system for sending multimedia (radio, TV, and datacasting) to mobil devices such as mobile phones. It can operate via satellite (S-DMB) or terrestrial (T-DMB) transmission. DMB is based on the Eureka 147 Digital Audio Broadcasting (DAB) standard, and has some similarities with the main competing mobile TV standard, DVB-H.
Like DAB, T-DMB is made for transmissions on radio frequency bands band III (VHF) and L (UHF), mainly for terrestrial and satellite, respectively. Because the United States and Canada still allocate the first band as for television broadcasting (VHF channels 7 to 13) and the United States reserves the L band for military applications, DMB is still unavailable in North America. Qualcomm's MediaFLO is a proprietary system used there instead. In Japan, 1seg is the standard, using ISDB.
T-DMB uses MPEG-4 Part 10 (H.264) for the video and MPEG-4 Part 3 BSAC or HE-AAC V2 for the audio. The audio and video is encapsulated in MPEG-2 TS. The stream is RS encoding and the parity word is 16 bytes length. There is convolutional interleaving made on this stream, then the stream is broadcast in data stream mode on DAB. In order to diminish the channel effects such as fading and shadowing, DMB modem uses OFDM-4DPSK modulation. A single-chip T-DMB receiver is also provided by an MPEG-2 transport stream demultiplexer. DMB has several applicable devices such as mobile phone, portable TV, PDA and telematics devices for automobiles.

DMB Transmission Structure.

KOREA T-DMB