LTE - the technology of the future

LTE (Long Term Evolution) is a technology of mobile networks in which the download speed will reach up to 326 Mb/s and upload speed up to 86 Mb/s (20 MHz channel, 64QAM modulation, 4x4 MIMO). The technology is seen as the next stage in the development of mobile networks, allowing them to achieve the possibility of efficient multimedia transmission. The popularity of smartphones (like iPhone) means the growing demand for mobile broadband networks. LTE technology is flexible, both in terms of frequency band and width of the transmission channel. Depending on the needs, LTE networks can operate at frequencies from 700 MHz (rural areas - higher ranges) to 2.6 GHz (metropolitan areas). It is possible to use transmission channels with the following bandwidths: 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz. With the increase in channel width, the link speed rises as well.
The "downlinks" use OFDM spread spectrum technique with multiple subcarriers, whereas the "uplinks" are based on SC-FDMA (Single Carrier Frequency-Division Multiple Access) that uses a single carrier (to save the battery life of the client device) . Additionally, LTE uses Multiple Input Multiple Output (MIMO) technology which utilizes many antennas. So far, client terminals are usually equipped with two antennas (MIMO 2x2), due to implementation problems in such small devices. An important element of LTE is a new network structure, called System Architecture Evolution (SAE). It is based entirely on IP protocol. The technology is evolving in two directions: FD-LTE and TD-LTE. They differ in the utilization of the channel. In the case of FD-LTE, the transmission channel is divided into two frequency bands - one of them is used for transmission towards the base station and the second from the base station to the terminal.
The TD-LTE uplink and downlink transmissions are spread over the whole channel. The time at which transmission is carried out is divided into time slots, separated by guard time. In each time slot the transmission goes only one way. This allows for flexible use of the capacity of the transmission channel.
Currently, TD-LTE is gaining more and more supporters; not without significance is the fact that it is chosen as the primary technology for building commercial LTE networks in China.
The first commercial LTE networks will be launched in 2010 (China, USA, Scandinavia, Japan), however, works are already carried out to develop a more advanced version of this technology, namely LTE-A (Advanced), with estimated throughput of 1 Gb/s (downlink) and 500 Mb/s (uplink) within a 100 MHz band.