Communication Trends Case Study

2.1. History of Communication Trends:

During the 19th and 20th century, the way of communication underwent evolutionary changes. While in the earlier ages the communication mainly took place from mouth to mouth or by sending letters, the introduction of the telegraph, the telephone, the fax machine, and the later transition to mobile phone services hugely improved the connectivity. Now, at the beginning of the 21st century, a transition that might turn out even more revolutionary is taking place as the Internet and other data communication applications move into the wireless domain.

Ubiquitous connectivity (i.e., connectivity anytime and everywhere) to the

Internet, to company's Intranets, or to other data services is creating room for applications that might not even be thought of today.

Regarding the latter transition, it is very interesting to observe the following two recent trends. Firstly, the amount of Internet (data) traffic is growing 300% per year and recently exceeded the amount of voice traffic.

Secondly, the International Telecommunication Union (ITU) forecasted in its world telecommunication development report of 2002 that the number of mobile voice subscriptions would exceed the number of fixed voice subscriptions in and beyond 2002.

When combining above two trends, a logic consequence must be that the amount of wireless data traffic will overtake the amount of wired data traffic

(at least from an end-user perspective). This statement is being supported by the increasing demand for augmented capacity, data rates, and data services due to:

The tremendous momentum in wireless technology created both by the successful deployment of second generation mobile systems,

e.g., GSM (including the quest for cheaper, smaller ...

... middle of paper ...

...e, especially in rich-scattering environments. This has been shown for wireless communication links in both narrowband channels as well as wideband channels, and it initiated a lot of research activity to practical communication schemes that exploit this spectral-efficiency enhancement.

The resulting multiple-transmit multiple-receive antenna, i.e., Multiple-Input

Multiple-Output (MIMO), techniques can basically be split into two groups:

Space-Time Coding (STC) and Space Division Multiplexing (SDM) --- STC increases the robustness/performance of the wireless communication system by transmitting different representations of the same data stream (by means of coding) on the different transmitter branches, while SDM achieves a higher throughput by transmitting independent data streams on the different transmit branches simultaneously and at the same carrier frequency.