UMTS The Universal Mobile Telecommunications System Computer Science Essay

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For the purpose of globalization, the future of mobile communication lies in the third generation 3G as it provides new functionalities with high quality. UMTS, the Universal Mobile Telecommunications System, is a 3G mobile communications technology that offers its services at any time and place. In addition to ensuring communication among people, it allows the use of mobile equipment for any application such as business, entertainment, and different types of services. UMTS stands for an evolution from 2G mobile communications with its high data speeds and enhanced services. The transmission speed increases up to 2Mbps for every mobile user and a global roaming standard is established. Thus, it can handle the increasing demand of internet and mobile applications.

As the new radio access method, 3G launches WCDMA (Wideband Code Division Multiple Access) which gives the subscribers access to all its networks. It permits the introduction of more applications to the huge number of users. WCDMA is better than TDMA in terms of spectral efficiency and packet transfer.

Access points can exchange information to provide the services offered by UMTS. The properties of a bearer service can be negotiated and renegotiated during the setup and ongoing of a connection [4]. Various QoS classes exist for four kinds of traffic in UMTS as shown in Table X.

Table 1: QoS Classes in UMTS [5][6]



Conversational class

Voice - Video gaming - Video telephony

Streaming class

Multimedia - Webcast - Video on demand

Interactive class

Database access - Web browsing - Network gaming

Background class

SMS - Email - Downloading

Some UMTS services provided are High Speed Downlink Packet Access (HSDPA) for point-to-point connections [5] [6], and Multimedia Broadcast/Multicast Services (MBMS) for point-to-multipoint connections [7] [8]. HSDPA

High Speed Downlink Packet Access (HSDPA) is a feature that permits up to 10Mbps data rates using a downlink shared data channel. Its purpose is to provide services that need instantaneous high rates in the downlink but lower rates in the uplink. It also allows for reduction in the delivery time by decreasing the level of retransmissions at the radio link and thus the higher layers.

Internet browsing and video streaming are two key examples of end-user services using HSDPA [9] [10]. It is an improved 3G mobile telephony communications protocol in the group of High-Speed Packet Access (HSPA). It is a protocol for mobile phones designed to increase the speed of data transmission rate and network capacity of mobile phones. This protocol is considered a relatively simple upgrade of UMTS. Current HSDPA deployments support down-link speed ranging from 1.8Mbps to 14.4Mbps, such an enhancement is a major target as the speed available to mobile technology is limited. Moreover, it can remarkably increase the transfer capacity. HSPA+, which ensures downlink speeds of up to 42Mbps, is a further improvement of speed that can reach 84Mbps with Release 9 of the 3GPP standards [11]. Thus, HSDPA advantages include enhancement of data rates in addition to reduction of round trip time for applications and thus latency. Up to 30 GB of data, 1000 minutes of talk time, and 300 minutes of mobile television viewing can be transferred monthly over an HSDPA network.

Current HSDPA Technology and Capable Devices

Nowadays, 100 HSDPA-enabled networks are distributed among 54 countries in the world. They provide 3.6Mbps or 7.2 Mbps downlink speeds. The full 14.4Mbps speed is reached by only few present networks. To log into the HDSPA network, mobile phones able to use this technology should be provided. In addition to many HSDPA notebooks and laptops, there are 171 handset models having this feature at present.


2.1. Wireless Networks 7

Future HSDPA Technology

Currently, HSDPA is offering 14.4MBps downlink speed over HSDPA. In the future, this speed will be improved to 42Mbps by the upgrade of networks, with a new kind of HSDPA system known as HSPA Evolved. MBMS

Existing GSM and UMTS cellular networks offer a broadcasting service known as Multimedia Broadcast and Multicast Services (MBMS). An option of using an uplink channel is offered by the infrastructure to provide interaction between the user and the service. Instead of point-to-point links for every end device, multicast distribution is used by MBMS in the core network. MBMS gives the opportunity to broadcast TV, film, and other live information such as daily newspapers.

The fact that the network infrastructure is already available constitutes a major benefit for mobile network operators as there is no need to construct a new network for the services and thus its deployment is cost effective. It also allows a maximum bit rate of 256Kbps.

The expansion of applications requiring high bandwidth in 3G systems requires efficient information distribution. A single source can transmit to multiple destinations using a broadcast/multicast in order to efficiently use network resources as less data is transferred. The network sends the data only once over a single common channel to mobile phones located in the same cell without having to send redundant data by multiple unicast sessions [12].

MBMS includes two services, which are multimedia broadcasting, which is used for broadcasting Live TV channels, and multicast services, for sending to specific devices. Services relying on MBMS are classified in streaming services (audio and video) or file download services.

Once received at the mobile device, the multimedia content can be directly played with multimedia services. The mobile device does not have to download a whole file before hearing the audio or viewing the video. This is a main enhancement over download services that store the multimedia content locally in a cache to be later processed.