Slavik Bryksin
[email protected] CSE237a Fall 08 Topic research Data transmission standards over GSM/UMTS networks 1. Introduction There are a lot of emerging and existing standards that are used for data transmission over cellular networks. This paper is focused on the GSM/UMTS networks technologies that are marketed as 2G through 3G, their underlying technologies and concepts (channel access methods, duplexing, coding schemes, etc), data transmission rates, benefits and limitations. The generation that preceded 2G GSM was analog, whereas all following generations are digital. Generation labeling is mostly for marketing purposes, thus some technologies that existed in 2G are carried over and labeled 3G (i.e. EDGE versions), moreover, the timeline of adoption of the protocols and their inclusion under the umbrella of a certain generation might not align with the technology inception and certification. 2. (2G) Technologies 2.1. GSM (Global System for Mobile communications) GSM data transmission protocol is circuit switched with a fixed rate of 9.6Kbps and uses TDMA (Time Division Multiple Access) to assign static downlink and uplink timeslots for data.[16] The fact that data rate is fixed leads to inefficient usage of the available bandwidth due to the bursty network traffic.[1] 2.2. GPRS (General Packet Radio Service) GPRS standard is marketed as 2.5G and was the next step after circuit switched GSM standards. It is packet switched, which implies better bandwidth utilization, however packetization of data incurs the cost of extra information included in the packet, and the overhead of negotiation of transmission with the base station.