In the past years Wireless Networks have become more popular than wired networks for end user devices. Apart from WLANs based on Wi-Fi, Public Wireless Networks based on GPRS, EDGE, UMTS, and HSDPA are getting more used every day. The reason is obvious – public wireless networks provide freedom to move around for mobile users and provide connectivity from places where wired connections are impossible (like on the road).
Public wireless networks are much less reliable than private. Users moving around will often temporarily lose connectivity, and bad signals lead to frequent re-sending of network packets. The bandwidth is also much lower than when using private networks; noise and other signal interference, usage of available bandwidth by (many) other users and retransmissions lead to low effective bandwidth per end point.
GSM, GPRS and EDGE
Global System for Mobile Communications (GSM) is the world's most popular standard for mobile telephone systems in which both signaling and speech channels are digital. This technology is also called 1G: the first-generation of mobile technology.
General packet radio service (GPRS) is a packet oriented mobile data service providing data rates of 56 to 114 kbit/s based on GSM technology. This technology is also called 2G.
Enhanced Data rates for GSM Evolution (EDGE), also known as Enhanced GPRS or 2.5G, allows improved data transmission rates as a backward-compatible extension of GSM. EDGE delivers data rates up to 384 kbit/s.
UMTS (3G) / HSDPA
Universal Mobile Telecommunications System (UMTS) is an umbrella term for the third-generation (3G) mobile telecommunications transmission standard. UMTS is also known as FOMA or W-CDMA. Compared to GSM, UMTS requires new base stations and new frequency allocations, but it uses a core network derived from GSM, ensuring backward compatibility. UMTS was designed to provide maximum data transfer rates of 45 Mbit/s.
High Speed Downlink Packet Access (HSDPA) is part of the UMTS standard, providing a maximum speed of 7.2 Mbit/s. HSDPA+ is also known as HSDPA Evolution and Evolved HSDPA. It is an upgrade to HSDPA networks, providing 42 Mbit/s download and 11.5 Mbit/s upload speeds.
LTE (Long Term Evolution) is a 4G network technology, designed from the start to transport data (IP packets) rather than voice. LTE is a set of enhancements to UMTS. In order to use LTE, the core UMTS network must be adapted, leading to changes in the transmitting equipment. The LTE specification provides download peak rates of at least 100 Mbit/s (up to 326 Mbit/s), and an upload speed of at least 50 Mbit/s (up to 86.4 Mbit/s).
LTE is not designed to handle voice transmissions. When placing or receiving a voice call, LTE handsets will typically fall back to old 2G or 3G networks for the duration of the call. In 2015, the Voice over LTE (VoLTE) protocol is about to be rolled out to allow the decommissioning of the old 2G and 3G networks in the future.