- UMTS Tutorial
Even non-GSM networks are choosing to add WCDMA support as it is the most popular 3G technology. Sooner or later older and competing network standards, namely GSM, CDMA, and EV-DO, would probably be phased out and replaced with WCDMA. Summary: 1.WCDMA is a 3G technology while GSM is a 2G technology 2.GSM is slowly being phased out in favor of CDMA.
- Cellular Concepts
- UMTS Introduction
- UMTS Networks Standardization
- UMTS Protocol Environment
Lte Gsm Umts Settings
- UMTS Useful Resources
- Selected Reading
The following new GPRS network adds the following elements to an existing GSM network.
Packet Control Unit (PCU).
Serving GPRS Support Node (SGSN) − the MSC of the GPRS network.
Gateway GPRS Support Node (GGSN) − gateway to external networks.
Border Gateway (BG) − a gateway to other PLMN.
Intra-PLMN backbone − an IP based network inter-connecting all the GPRS elements.
General Packet Radio Service (GPRS)
GPRS introduces packet data transmission to the mobile subscriber.
GPRS is designed to work within the existing GSM infrastructure with additional packet switching nodes.
This packet mode technique uses multi-slot technology together with support for all coding schemes (CS-1 to CS-4) to increase the data rates up to 160 kbit/s.
The GPRS system uses the physical radio channels as defined for GSM. A physical channel used by GPRS is called a Packet Data Channel (PDCH).
The PDCHs can either be allocated for GPRS (dedicated PDCH) or used by GPRS only if no circuit-switched connection requires them (on-demand). The operator can define 0-8 dedicated PDCHs per cell. The operator can specify where he wants his PDCHs to be located.
The first dedicated PDCH in the cell is always a Master PDCH (MPDCH). The on-demand PDCHs can be pre-empted by incoming circuit switched calls in congestion situations in the cell.
| Coding Scheme | Speed(kbit/s) |
| CS-1 | 8.0 |
| CS-2 | 12.0 |
| CS-3 | 14.4 |
| CS-4 | 20.0 |
Serving GPRS Support Node (SGSN) Functions
The SGSN or Serving GPRS Support Node element of the GPRS network provides a number of takes focused on the IP elements of the overall system. It provides a variety of services to the mobiles −
- Packet routing and transfer
- Mobility management
- Authentication
- Attach/detach
- Logical link management
- Charging data
There is a location register within the SGSN and this stores the location information (e.g., current cell, current VLR). It also stores the user profiles (e.g., IMSI, packet addresses used) for all the GPRS users registered with the particular SGSN.
Gateway GPRS Support Node (GGSN) Functions
The GGSN, Gateway GPRS Support Node is one of the most important entities within the GSM EDGE network architecture.
The GGSN organizes the inter-working between the GPRS/EDGE network and external packet switched networks to which the mobiles may be connected. These may include both Internet and X.25 networks.
The GGSN can be considered to be a combination of a gateway, router and firewall as it hides the internal network to the outside. In operation, when the GGSN receives data addressed to a specific user, it checks if the user is active, then forwards the data. In the opposite direction, packet data from the mobile is routed to the right destination network by the GGSN.
Upgradation of Equipment from GSM to GPRS
Mobile Station (MS) − New Mobile Station is required to access GPRS services. These new terminals will be backward compatible with GSM for voice calls. Three types of handsets are available. Type-A: GPRS & Speech (simultaneously), Type-B: GPRS & Speech (Auto switch), Type-C: GPRS or Speech (manual switch).
BTS − A software upgrade is required in the existing base transceiver site.
BSC − Requires a software upgrade and the installation of new hardware called the packet control unit (PCU). PCU is responsible for handling the Medium Access Control (MAC) and Radio Link Control (RLC) layers of the radio interface and the BSSGP and Network Service layers of the Gb interface. There is one PCU per BSC. The Gb interface, carry GPRS/EGPRS traffic from the SGSN (Serving GPRS Support Node) to the PCU.
GPRS Support Nodes (GSNs) − The deployment of GPRS requires the installation of new core network elements called the serving GPRS support node (SGSN) and gateway GPRS support node (GGSN).
Databases (HLR, VLR, etc.) − All the databases involved in the network will require software upgrades to handle the new call models and functions introduced by GPRS.
Location Information - GSM Service Area Hierarchy
Cell − Cell is the basic service area and one BTS covers one cell. Each cell is given a Cell Global Identity (CGI), a number that uniquely identifies the cell.
LA − A group of cells form a Location Area. This is the area that is paged when a subscriber gets an incoming call. Each Location Area is assigned a Location Area Identity (LAI). Each Location Area is served by one or more BSCs.
MSC/VLR Service Area − The area covered by one MSC is called the MSC/VLR service area.
PLMN − The area covered by one network operator is called PLMN. A PLMN can contain one or more MSCs.
GSM Service Area − The area in which a subscriber can access the network.
GSM vs UMTS
GSM is an abbreviation of Global System for Mobile communication, originally it is known as Group Special Mobile. It is mobile telephony system that sets the standards on how mobile telecommunications work. It encompasses everything in reference to mobile communications.
However, in this context of comparing GSM and UMTS, we will refer to GSM as a service or technology. GSM is a second generation (2G) telecommunications technology which is launched early in the 90s. Eventually, it increased its speed and added more functionality like General Packet Radio System (GPRS) to the system which enhanced it to 2.5G status. 2.5G has data rates up to about 144kbit/s. It typically uses a variation of Time Division Multiple Access (TDMA).
Today, in a global scale, GSM is still widely used mobile service. There are about 700 mobile networks that provide GSM services across more than 200 countries. Statistically, more than 80 percent of all global mobile connections are GSM. With GSM, subscribers can still continue using their mobile phones when traveling to other countries because GSM network operators have expansive roaming agreements with foreign operators.
UMTS is the third generation (3G) of mobile telecommunications technology. It is the latest commercially available technology that mobile phones, PDAs, and smart phones are using today. With this development, internet access (email and web browsing), video calling and messaging, and text messaging (SMS) are now possible along with traditional phone tasks.
People can now do the activities they normally do with an internet-connected home computer while on the trot. Imagine yourself traveling the world and still able to email, video conference, and watch streaming videos using your smartphone. Currently, it can offer transfer speeds of about 3.6 Mbits per second and even more, which can make data transfer seamless and downloads relatively fast.
What Is Lte Gsm Umts
Unlike GSM, UMTS is mainly based on CDMA (Code Division Multiple Access) scheme and now combines it with TDMA. However, UMTS is still new as there are only a few areas and networks that support the technology. Even with countries that support it may have set different spectrum, thus interoperability does not work fully when moving from one nation to another nation with drastically different spectrum.
There are also problems regarding the compatibility between UMTS and GSM, which frequently led to connections being dropped. But this is being remedied by UMTS/GSM dual-mode devices. With that feature, UMTS phones that go out of UMTS network boundaries will be transferred to GSM coverage. Transfer of network can happen mid-call.
Summary:
1. UMTS has faster data transfer rates than GSM.
2. GSM is 2G and 2.5G while UMTS is already 3G.
3. GSM is a rather old technology while UMTS is newer.
4. GSM is typically based on TDMA while UMTS is mainly CDMA-based.
5. Currently, GSM is still the most widely used technology today while UMTS is still in its infancy, slowly creeping forward.
Ian
Gsm Vs Umts
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