High speed data in mobile network.
The Need for High Speed Mobile DataWhy High Speed Mobile Data?The ever increasing growth rate of data applications such as e-mail and the internet in mobile network operators worldwide with the challenge to upgrade their networks to high bandwidth capable "bit pipes" in order to provide for all kinds of mobile data applications. High speed mobile data will combine two of today's most rapidly growing technologies, mobility and the internet.
Let us compare the situation on the mobile side with the progress that has been made on the fixed end. While even today's analog modems operate at 56 Kbit/s and, indeed, ISDN transmits up to 128 Kbit/s, mobile users are still limited to 9.6 Kbit/s in of GSM. The rollout of XDSL improves the situation even further on the wire line side, thereby broadening the gap between wire line and wireless.
Customer Potential With regard to mobile data, not just the typical pattern of use by today's businessmen on the move shall be addressed: Today's GSM-networks are also used by many consumers for the largest growing mobile data application of the late 1990's, SMS. Therefore, the new mobile data technologies need to address both consumer groups, the private customer and the business user. In the first instance, most network operators intend to attract their high-end business subscribers, their long term goal being, however, to bring high speed mobile data to the mass market.
High Speed Data Options for GSM The figure below illustrates the evolution of data services in GSM. Please note that packet-switched services are illustrated in switched services are shown in blue.
An Historical ViewGPRS (General Packet Radio Service), EDGE (Enhanced Data rates for Global Evolution) and HSCSD (High Speed Circuit Switched Data) have been designed primarily as upgrades to the well known and widely used GSM standard. In the 1980s and early 1990s, when the GSM system was designed and standardized, data transmission capabilities were of minor importance compared to voice. Besides, at that time, the maximum transmission speed of 9.6 Kbit/s that GSM offered, appeared to be sufficient and was comparable with analog wire line modems.
Starting with HSCSD, the first high speed mobile data upgrade to be standardized, higher rates of transmission can be provided to mobile customers. EDGE has a transmission speed of up to 384 Kbit/s and GPRS is able to support up to 160 Kbit/s.
The Application Perspective Applications for High Speed Mobile Data Today, many business and marketing experts worldwide are seeking the ultimate "killer application" to justify the huge investments in high speed data upgrades and 3G-technology. People generally focus on e-mail, file transfer and accessing the WWW for the usual internet transactions when considering applications for high speed mobile data. These applications will, of course, be important but there will also be new applications which will suit the specific needs of mobile usage. Despite this, many new applications will only come into being when the mobile networks have been upgraded. For those applications, the mobile device, as we know it, will not be deployed. However, even today, entirely new mobile data applications that do not involve the common mobile user or usage are already emerging.
Advantages of High Speed Mobile Data: Some of the applications have already been evaluated and some have indeed been implemented using the existing wireless infrastructure. However, in most cases, the technicians were faced with the irresolvable issue of connectivity. In other cases, a network for providing a connection was available but simply was not designed for data applications. These required the development of an entirely new protocol stack. With regard to the upcoming high speed mobile data services, well-known and well-understood protocol stacks such as IP may be used to develop the applications.
Problems of High Speed Mobile DataHigh speed mobile data will certainly improve the existing mobile networks greatly. GPRS and EDGE, in particular, will write a new chapter in mobile communications history. However, there are various problems which need addressing in order to make high speed mobile data a commercial success. Firstly, who shall provide all the necessary IP-addresses when many people are permanently online? Even today, a shortage of IP addresses is becoming evident. The only solution to this issue is an upgrade to IP version 6 but the question is when IP version 6 become a reality will.
Another problem is the short span between GPRS, EDGE and UMTS. Even before the demand for GPRS has been proven, the technical evolution has already found successors to GPRS, namely EDGE and UMTS. Perhaps the market will not be ready for UMTS when it becomes available in 2002. Most importantly, however, there is one fundamental question: Is there really a market for high speed mobile data or will GPRS, EDGE and UMTS suffer like the mobile satellite networks? The later is the issue which really needs to be addressed. On the one hand, the content providers need to examine this issue and on the other hand, the network and service operators need to be willing to accept changes to the value chain so that content providers can also prosper from the mobile communications market.
GPRS GPRS is a packet-switched upgrade to GSM. What consequences does packet-switching actually have on a mobile network? How does GPRS perform in comparison with e.g. HSCSD? How will the GSM networks need upgrading in order to implement GPRS ?PrinciplesGPRS is Packet-Switched:GPRS or General Packet Radio Service is a packet-switched technology based on GSM. As shown in the animation, the radio and network resources are only accessed when data actually needs to be transmitted between the mobile user and the network. Please note that in between alternating transmissions, no network resources need to be allocated. Compare this to the circuit-switched transaction where resources are being accessed permanently, regardless of whether or not transmission is actually talking place. Therefore, packet-switching saves resources, especially in the case of burst transactions.
HSCSDHSCSD is circuit-switched and hardly any operator decided to implement it. This sub clause will provide you with an overview of HSCSD. It will describe its principles and performance and it will explain why HSCSD is the simplest high speed data upgrade for GSM.
The Principles of HSCSD:
HSCSD or High Speed Circuit Switched Data was the first upgrade to be standardized by ETSI to bring high speed data to GSM. The standardization process started as early as 1994 and therefore, HSCSD was the first high speed data extension to be ready for implementation in 1999. The basic idea behind HSCSD is to bundle more than one timeslot on the air-interface for a single connection. Applying this simple idea, HSCSD is able to reach throughput rates of up to 57.6 Kbit/s. However, the real-life implementations of HSCSD barely exceed 38.4 Kbit/s.
EDGEEDGE will provide the highest speeds in the second generation of mobile networks. However, how can EDGE achieve these high throughput rates compared to GPRS or HSCSD? Is EDGE really the third alternative to GPRS and HSCSD with regard to high speed mobile data? If EDGE is so superior to HSCSD and GPRS, why not upgrade directly to EDGE, leaving out HSCSD and GPRS? Indeed, why is the mobile industry in the US also talking about EDGE ?
ConclusionHigh speed mobile data will certainly improve the existing mobile networks greatly. GPRS and EDGE, in particular, will write a new chapter in mobile communications history. Currently, almost all network operators worldwide are upgrading their GSM networks in order to provide high speed mobile data to their subscribers. HSCSD is a circuit-switched technology. Therefore, one of its major advantages is that the existing core network, mainly the MSC, is able to handle HSCSD traffic. As opposed to GPRS, HSCSD neither requires a hardware upgrade within the network, nor does it introduce new channel coding technologies. Therefore, HSCSD is a rather simple upgrade of the standard GSM, particularly in comparison with GPRS and EDGE.