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ERICSSON GLOBAL | |
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Understanding the standards
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Books and articles are excellent ways to get into new technical areas and to understand actual implementation. But many developers need to dig deeper into technology to find out exactly what the standards state. This can be a challenge, as the standards might be hard to find and difficult to navigate. Some people do not even know who is responsible for a standardization area.
Friday, May 23, 2003
GPRS and 3G Mobile Networks The mobile networks and associated architectures can be divided into WCDMA, with GSM based evolution, and cdma2000. GSM, GPRS, EDGE and WCDMA (UMTS) are standardized in the Third Generation Partnership Project (3GPP), where the standardization is based on releases and the evolving technology. The technical specification groups (TSG) in 3GPP include: TSG SA (Service and System Aspects) TSG CN (Core Network) TSG RAN (Radio Access Network, WCDMA and TDD) TSG GERAN (GSM, GPRS and EDGE Radio Access Network) TSG T (Terminal aspects). 3GPP has had four complete releases and a fifth release is in progress. The first release, known as Release 1997, was created by the European Telecommunications Standards Institute Special Mobile Group (ETSI SMG), a predecessor to 3GPP. This release added GPRS and packet data to existing GSM systems. Release 1999 saw the addition of WCDMA (UMTS), with high-speed packet and circuit-switched data. Commercial operations for this technology started in 2002 and picked up in 2003. The next two releases, Releases 4 and 5, added more IP functionality, Time TDD mode for the radio network, better support for applications, quality of service improvements and IP Multimedia Subsystems (IMS). Release 6 is still in progress, but features that will be added include IMS phase 2, Digital Rights Management and improved quality of service handling. Additional GSM/EDGE Radio Access Network specifications are available in GSM/EDGE Releases 4 and 5. Then for each release of the standard, there is a quarterly update (e.g. 3GPP Release 1999, March 2001), which contains change requests for corrections to Release 1999, which were approved by March 2001. It is important to mention that no new functionality is introduced by change requests to a frozen release. Visit the 3GPP Specifications - Release contents and functionality website for more in-depth information on each release and its main improvements. The 3GPP standards can be a bit difficult to read for beginners, although they are freely available on the Internet. The status document can be used to find the document numbers of areas of interest or use this link to find more in-depth information. The excerpt below shows the overview of terminal interfaces supported in the next Release of 3GPP (Release 4). The document TR 27.901 can be found in the ftp database.
The FTP site lists directories for the different workgroups and the specifications are grouped by 3GPP-meetings and releases (for example, the output from the December 2000 meeting is at ftp://ftp.3gpp.org/Specs/2002-12/). Just choose which release of the standard you want to look at. For example, to check out the first release of the WCDMA (UMTS) system, choose R1999. cdma2000 is standardized by the Third Generation Partnership Project 2 (3GPP2). The setup is similar to 3GPP, with releases and the task of producing its specifications located in four technical specification groups (TSGs) comprised of representatives from the project's individual member companies (vendors, operators and others). These groups are TSG-A (Access Network Interfaces), TSG-C (cdma2000), TSG-S (Services and Systems Aspects), and TSG-X (Intersystem Operations). Click here for the 3GPP2 specifications.
The overall application architecture for cellular networks is described in 3GPP but there are other bodies that standardize many of the application enablers. The cycles for application standards are shorter and it is faster to get products on the market, therefore it is good to get acquainted with the appropriate standards. The Bluetooth Special Interest Group (SIG), which now has over 2000 members standardizes Bluetooth. Click here for the Bluetooth specifications or visit Bluetooth.org. There are two main documents for each version of the standard: the main specification and the profiles specification. Note that these files are big, and choosing "Print target" in your browser might make you unpopular among people who are using the same printer. Parlay is an organization that drives the standardization of open Application Programming Interfaces (APIs) that developers can use. This includes call control and charging features that are not usually available outside the mobile network. Click here for the current version of Parlay 4.0 specifications. Previous releases can be found on the archive page. As these features are tightly connected to the operator's network, it is essential to check with the operator as to which APIs are supported. Call control is the first enabler that is expected to be implemented using Parlay specifications and companies such as Telefonica and Solomio have announced launch of Parlay-based call-control applications during 2003. The Open Mobile Alliance (OMA) was created in June 2002 to unify several enabler standardization organizations, including WAP Forum, SyncML Forum, Location Interoperability Forum and Wireless Village. The focus is set on bringing the whole value chain together to create enablers that encourage easy application development. OMA also aims specifically to combine the different enablers to maximum benefits of them working together. The standards will be related to test specifications in order to make enablers and handsets interoperable, regardless of the vendor. The first specifications released by OMA are: OMA Browsing OMA Multimedia Messaging Service (MMS) OMA Digital Rights Management (DRM) OMA Domain Name Server (DNS) OMA Download OMA E-mail notification OMA Billing Framework OMA Client Provisioning OMA User Agent profile OMA Instant Messaging and Presence server (IMPS). The OMA standards are defined in three phases where phase one is the Candidate Enabler Release, used in products and solutions, which then can be tested for interoperability. Phase two, the Approved Enabler Release, is for the enabler that has passed phase one and associated test cases have been generated. Phase three, OMA Interoperability Release, is used when several enablers have been tested and approved. One of the key aspects that OMA has added to the standardization work is to connect specifications with test cases. OMA then arranges so-called "test fests", where vendors gather to test handsets and infrastructure. Multimedia Messaging Service (MMS) is standardized in two bodies, OMA and 3GPP, and is a natural evolution for today's messaging technologies. The hugely popular Short Message Service (SMS) has taken the world by storm and has become a huge cash cow for mobile operators. In 2002, there were over one billion messages sent each day worldwide. With MMS, photos or entire multimedia presentations that contain images, sounds, text and later also video clips can be attached and sent. The presentations can be sent either between mobile devices or between a mobile device and a fixed PC with e-mail capabilities. In the 3GPP specifications (see above) the documents TS 22140 and TS 23140 contain the MMS specifications for phase one and two, respectively (Release 1999). Reading the standards is not always easy, especially when it comes to the telecoms world. Reading articles and books is usually an easier way to understand how things work at high level. However, it only brings you to a certain level, and many developers will have to look into the details of the specifications in order to get ahead in the development process. Hopefully you now are fit to face this challenge.
Christoffer Andersson is a director of business development at Ericsson. He is the author of the Amazon.com best-selling book 'GPRS and 3G Wireless Applications - The Professional Developer's Guide', published by John Wiley & Sons.
Last published January 20, 2009
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